immunopathogenesis of celiac disease · ca gastrointestinal más frecuente, afectando al 1% de la...

313

RESUMEN La Enfermedad Celiaca (EC) o Enteropatía Sensible al Glu-

ten, es una alteración del intestino delgado proximal producidapor una intolerancia inmunológica permanente a las prolami-nas del gluten. La EC provoca una intolerancia a la ingesta decereales habituales en la dieta occidental: el trigo, el centeno, lacebada y, posiblemente, la avena. La EC es la enfermedad cróni-ca gastrointestinal más frecuente, afectando al 1% de la raza cau-cásica.

El contacto con el gluten desencadena una inflamación cró-nica intestinal de base autoinmune, cuya lesión histológica carac-terística es una atrofia vellositaria reversible. Requiere para sumanifestación un contexto genético conferido por la presencia dedeterminados alelos del HLA. El diagnóstico se basa en la demos-tración de una relación causal entre la ingesta de gluten y la pre-sencia de una enteropatía característica. El único tratamiento esla difícil exclusión del gluten de la dieta.

La hipótesis patogénica más aceptada consiste en el desarro-llo de una respuesta inmune aberrante al gluten y el desencade-namiento de una enteropatía mediada por linfocitos T activadoslocalmente. Aunque los mecanismos que desencadenan la EC nose conocen, se ha descrito una reacción inmune de los linfocitosCD4+ de la lámina propia frente a péptidos del gluten deamida-dos por la enzima transglutaminasa tisular (tTG) y presentadospor HLA-DQ2 o DQ8, así como una reacción en el epitelio intes-tinal mediada por linfocitos intraepiteliales (LIE) CD8+ citotóxi-cos.

El estudio de los mecanismos inmunológicos que subyacenen la EC podría permitir el avance en el conocimento de la pato-genia de otras enfermedades inflamatorias y autoinmunes, ade-más de abrir nuevas vías terapéuticas para la EC.

PALABRAS CLAVE: Celíaca/ Transglutaminasa/ LIE/ Gluten/Autoinmunidad.

ABSTRACTCeliac Disease (CeD), or Gluten Sensitive Enteropathy (GSE),

is an immunologically-mediated intolerance to dietary prolamins.A cellular immune response against these cereal-derived proteinsimpairs the absorption of nutrients by the small intestine and leadsto a loss of the normal mucosal architecture and subsequent cli-nical and metabolic complications. Prolamins are a component ofgluten, present in wheat, rye, barley and oats, common ingre-dients of Western diets, and CeD is the commonest chronic gas-trointestinal disease in Caucasians (1% prevalence).

Ingestion of gluten provokes a chronic inflammatory responsethat induces a flattening of intestinal villi in genetically-condi-tioned subjects. This auto-aggression is reversible when gluten iswithdrawn from the diet, and a radical avoidance of those cere-als is the only available management of CeD. The temporal asso-ciation between gluten intake and histological changes constitu-tes the basis for the diagnosis.

The most accepted pathogenic mechanism of CeD is the pre-sentation of gluten peptides by HLA-DQ2 and -DQ8-bearing anti-gen presenting cells (APC) to T lymphocytes in the intestinal muco-sa. Those peptides would be modified by the enzyme tissue trans-glutaminase (tTG) and become high-avidity binders for those HLAmolecules. The ensuing immune reaction would involve CD4+

lymphocytes in the lamina propria and CD8+ cytotoxic intraepit-helial lymphocytes (IEL) in the epithelium.

Further research is needed to define the mechanisms that leadto the absence of immunologic tolerance to gluten and to deve-lop potential strategies to restore it.

KEY WORDS:

KEY WORDS: Celiac/ Transglutaminase/ IEL/ Gluten/ Autoim-munity.

RevisiónInmunología

Vol. 24 / Núm 3/ Julio-Septiembre 2005: 313-325

Immunopathogenesis of celiac diseaseF. León1, L. Sánchez2, C. Camarero3, C. Camarero4, G. Roy5

1Clinical Discovery-Immunology, Bristol-Myers Squibb, Princeton, USA. 4Pathology Department, Hospital de Cruces, Barakaldo, Spain;Departments of 2Hematology, 3Pediatrics, and 5Immunology, Hospital Ramón y Cajal, Madrid, Spain.

INMUNOPATOGENIA DE LA ENFERMEDAD CELIACA

Recibido: 2 Septiembre 2005Aceptado: 15 Septiembre 2005

Inmunologia bn 72p 26/10/05 10:45 Página 313

314

IMMUNOPATHOGENESIS OF CELIAC DISEASE VOL. 24 NUM. 3/ 2005

HISTORICAL PERSPECTIVEAs early as in II BC, Areteus of Cappadocia already

wrote on a clinical entity very similar to CeD, but it wasSamuel Gee in Britain who first described the disease as wecurrently know it and who first advocated for diet as themanagement, in 1887(1). In the 50’s, Dicke observed therelationship between gluten intake and CeD after noticinga reduction in the numbers of CeD patients in Hollandduring the food shortages provoked by World War II(2),as well as their increase when conditions subsequentlyimproved.

Historically, the diagnosis of CeD relied on the clinicalsymptoms and signs exclusively, and the characteristicpathologic changes of the gut mucosa observed duringautopsies were initially considered just a postmortem artifact.When endoscopy was introduced in the 50’s and jejunalbiopsies were studied(3,4), those changes became a hallmarkof CeD: villous atrophy, cryptal hyperplasia and increasedlymphoid density(5). Nowadays, the causal relationshipbetween gluten intake and histological changes remains atthe core of the diagnosis of CeD.

From the 70’s, a number of associated antibodies (Abs)and auto-antibodies were discovered: anti-reticulin, -gliadin,-jejunal and -endomysial antibodies(6). These Abs allowedfor a highly specific and sensitive screening of CeD and itsimplementation in at-risk populations demonstrated thatCeD is very prevalent, often asymptomatic and notablyunder-diagnosed (the «celiac iceberg»)(7).

In addition, two markers have been found to be presentin virtually all CeD patients: the major histocompatibilityantigen (HLA) HLA-DQ2(8) and an increase in intraepitheliallymphocytes (IEL) bearing the γδ Tc-receptor (TcR)(9). Thesefindings prompted a pathogenic hypothesis for CeD inwhich gluten peptides would be presented to mucosal CD4+

Tc by HLA-DQ2, in a mode that would break tolerance.This abnormal or exacerbated presentation hypothesis hasgained momentum since the discovery of the biochemicalmodification of gluten peptides by the enzyme tissuetransglutaminase (tTG)(10), which happens to be the antigenof anti-endomysial autoantibodies(11).

Supporting this theory, gluten-specific HLA-DQ2-restrictedTc clones have been found in the gut mucosa of CeD patients(12,13).Immuno-dominant epitopes had been long known in thegluten sequence(14-17) but it was not until recently that themechanism by which those peptides could gain access to thejejunal epithelium was elucidated. In vitro digestion ofrecombinant α2-gliadin with gastric and pancreatic enzymesgenerates a 33-aminoacid peptide rich in proline and glutamine,very stable and resistant to gastric enzymatic digestion, whichcontains multiple copies of the 3 epitopes most frequently

recognized by mucosal Tc of CeD patients(18). In addition,this 33-mer peptide is very susceptible to deamidation bytTG, rendering a highly immuno-stimulatory peptide amenableto DQ2 presentation to α-gliadin-specific Tc(19). Finally,homologues of this peptide have been found in all the cerealsthat are toxic for CeD patients, but not in non-toxic cereals.The pieces of the puzzle seem falling into place, and CeDmay be the first auto-aggressive disease in which the specificantigen and HLA restriction is known.

OVERVIEW OF CELIAC DISEASECeliac Disease (CeD, CIE10: Q90.1; MIM: 212750)(1,20-23)

or Gluten-Sensitive Enteropathy (GSE) is an immune-mediated chronic small bowel disease caused by intoleranceto prolamins, the proteic and alcohol-soluble fraction ofgluten, a major component of some of the commonest cerealsin the western diet: wheat, rye, barley(2,24,25).

The effects of gluten in celiacs can manifest weeks ormonths after its ingestion. There is considerable clinicalheterogeneity in the presentations of CeD. The classicpresentation is more frequent in children, with gastrointestinal(GI) symptoms and signs (distended abdomen, diarrhea,failure to thrive, muscle mass loss) and potentialmalabsorption(26). Also in children, but particularly inadults(27), CeD can manifest itself with a wide variety ofpresentations, including metabolic defects (vitamin deficiencies,iron-deficiency anemia), dermatological signs (dermatitisherpetiformis), reproductive or neuro-psychiatric abnormalities,etc... Dermatitis herpetiformis (DH) is, rather than a signof CeD, a gluten-sensitive entity in itself, with sub-epidermalIgA deposits and blister formation, in which 10% of thepatients have no evidence of GI disease and 90% areasymptomatic except for the skin lesions.

CeD generally starts in childhood, with a first peak ofincidence at 5 years of age. The second peak is in the 4thdecade of life, but the onset of CeD can take place at anyage. CeD is more frequent in females, with a 2:1 bias withrespect to males(21).

The prevalence of CeD in the general population rangesfrom 1/90 (Italy) to 1/300 (England(28)) in Europe(29-31),and 1/250 in North-America(32,33). These figures include theatypical forms of CeD which will be described in detaillater, namely silent (asymptomatic) and latent (no atrophy)CeD(34-36). CeD is rare in Asia, unsurprisingly given theimportance of the diet and the genetic background in thisdisease; accordingly, its frequency is increased in Asianimmigrants to Western countries(37).

The diagnosis is increasingly done in adults, given theimprovement of screening techniques and the high rate of


315

INMUNOLOGÍA F. LEÓN, L. SÁNCHEZ ET AL.

asymptomatic disease(38,39): in New Zealand, the prevalencein adults is estimated to be 1.2%, of which 90% are undiagnosedsilent CeD cases(40). Only 25% of new diagnoses in adultsare done in patients with symptoms from childhood. Globally,the incidence and prevalence of CeD have increasedsteadily(7,41). Large screening studies performed in healthyblood donors and school-age children(39,42-44) have shownthat the prevalence of sub-clinical forms out-weights clinicalCeD 3 to 1, what has been termed the «CeD iceberg»(7,30).Populations at risk for CeD include type I Diabetes Mellitus(DM-I)(45), Down Syndrome(46,47), IgA Deficiency(48) and first-degree relatives of CeD patients(49).

The screening of CeD is performed by means of thedetection of associated serum antibodies and autoantibodies,such as anti-reticulin(50), anti-gliadin (AGA)(51), anti-endomysial(EMA)(6) and, most recently, anti-transglutaminase. The

titer of these antibodies decreases after treatment, thusconstituting useful tools to monitor dietary compliance andcomplications(52-56).

The confirmation of the diagnosis is based upon thedemonstration of a causal relationship between gluten intakeand the characteristic enteropathy of CeD (cryptal hyperplasia,increased lympho-plasmocytoid cellularity in the laminapropria(5) and increased IEL(57,58)). If GFD is not established,the histological lesion progresses towards epithelial atrophyand loss of epithelial villi (Figs. 1-3) and, at the cellular level,loss of enterocyte microvilli (Figs. 4-5). For this reason, asmall bowel biopsy is mandatory, and is obtained by capsule(4)

or oral endoscopy(3,59). These alterations are not pathognomonicof CeD, and can also be observed in other diseases(60) suchas in gastroenteritis and post-enteritis syndrome, in foodallergy –particularly to soy and cow milk(61)-, in parasite

Figure 1. Normal jejunal mucosa. Left image, haematoxylin-eosin (HE), original magnification 200 x. Right image, scanning electron microscopy (SEM),original magnification 300 x.

Figure 2. Normal jejunal epithelium. Left image, apical or lumen side of a jejunal villus, HE, original magnification 2000 x. Right image, enterocite brushborder, electron microscopy (EM), original magnification 22000 x.


316


infestations (Giardia, Cryptosporidium and nematodes),etc., in children. In adults, these histological changes can beobserved in tropical sprue, immuno-deficiencies, lymphomas,Crohn’s disease, and other diseases. This lack of specificityof the intestinal biopsy makes it necessary to repeat thestudy 2 or 3 times, depending of age at onset and the clinicalpicture, in order to firmly demonstrate a causal relationshipbetween gluten intake and the enteropathy. A first biopsyis performed as initial diagnosis, a second one after glutenwithdrawal and improvement of the clinical signs, and athird one during a gluten challenge(62). In 1990, the criteriaof the European Society of Pediatric Gastroenterology andNutrition (ESPGAN)(63) were revised in order to require asingle biopsy in children over 2 years of age, and two biopsiesin those asymptomatic patients in which improvement withdiet could not be assessed clinically. There are still threesituations in which a third biopsy is mandated during

Figure 3. Epithelial atrophy in Celiac Disease, scanning EM. Scanning electron microscopy images of normal apical jejunal mucosa (left, originalmagnification 960 x) and active Celiac Disease jejunal mucosa (right, original magnification 450 x). Note cryptal cavities and remainders of villi in thisTotal Atrophy stage

Figure 5. Schematic and histological representation of the stages ofCeliac Disease enteropathy. From normality (1) to total atrophy (5). HE,original magnification 200 x.

Figure 4. Epithelial atrophy in Celiac Disease, EM. Electron microscopy images of normal microvilli on the apical surface of a normal enterocyte (left,original magnification 22000 x) and severe brush border lesion in Celiac Disease (right, original magnification 22000 x).


317


challenge: when the onset takes place before 2 years of age,when the first study is ambiguous (because serology orhistology are negative), or if the patient demands it(63).

Treatment of CeD is based on lifelong withdrawal ofgluten from the diet, what facilitates the repair of the mucosalarchitecture, the normalization of total IEL numbers (exceptfor γδ IEL, which remain elevated) and a clinical and functionalrecovery. Gluten-free diet (GFD) is expensive and difficultto follow for many patients. The safety threshold is only 50mg of gluten per day and the average consumption is 13gr/day(64), what illustrates the difficulty of carrying out thisrestrictive diet. Occasionally, after a period of adequateresponse to therapy, the patient fails to respond any longer,situation that is termed «Refractory Celiac Disease» and isoften accompanied by signs of lymphomagenesis that canevolve into a full-blown lymphoma(65,66).

Complications arise in the absence of complete GFD andinclude osteoporosis, chronic anemia, increased susceptibilityfor autoimmune disease(67), reproductive abnormalities(68),obstetric complications(69), jejunal ulcers, etc. Neoplasiasappear in 10% of untreated patients, mainly digestive cancer(mouth, pharynx, esophagus(70)) and intestinal Tc lymphomas(71).In childhood, due to the loss of absorption through the villi(Figs. 3-4) complications are mainly nutritional, metabolicand growth abnormalities, but also a growing number ofmalignant complications(72). Importantly, a correct GFDeliminates the increased risk for complications, stressingthe need for early diagnosis and for screening of subjects atrisk.

The etiology of CeD is unknown(73-75). Hypothesis includetoxic, enzymatic, infectious(76,77) and immune origins(78), beingthe immune hypothesis the most accepted since the discoveryof the involvement of the gut-associated lymphoid tissue(GALT) in the mucosal effects of gluten in CeD(79).

GENETICS OF CELIAC DISEASEThe genetic component of CeD is clear(80) and is based

on the significant association of CeD with certain HLA classII alleles. Up to 20% of first-degree relatives of CeD patientsare affected by the disease. Monozygotic twins have a80% concordance rate(81,82), of which the HLA complexexplains 40%(74). In 91% of patients, CeD is linked to the HLAheterodimer HLA-DQA1*0501, DQB1*0201, serologicallydefined as HLA-DQ2, and encoded in cis in haplotype DR3-DQ2 and in trans in haplotype DR5/DR7-DQ2(8,83-86). MostDQ2-negative patients possess the heterodimer HLA-DQA1*0301, DQB1*0302 (in haplotype DR4-DQ8)(87). However,given that HLA-DQ2 is present in 25-30% of healthy Caucasiansand that the prevalence of CeD is 1% in this population, it

seems clear that factors other than the HLA must play a rolein the development of the disease.

However, little is known about the role of non-HLAgenes in CeD. Recent studies have suggested an associationwith polymorphisms in the negative regulator moleculeCTLA-4(88-90), what is consistent with its function and withfindings in other autoimmune diseases. The other geneticregion associated so far to CeD is the long arm of chromosome5 (5q 31-33)(91-93) that harbors several genes of importancefor the immune system.

ROLE OF GLUTEN IN CELIAC DISEASEThe pathogenic role for gluten present in wheat is known

since the 50s(94). Gluten proteins can be classified accordingto their solubility into glutenins (alcohol insoluble) andgliadins (α, β, γ and w; alcohol soluble(99)). Not only gliadinsin gluten, but also secalins in rye and hordeins in barley, aswell as possibly avidins in oats, are toxic for celiac patients(95).Some studies suggest glutenins can also damage the intestinalmucosa(96-98).

The prolamins of gluten are characterized for their highcontent in the aminoacids glutamine and proline, while theprolamins of rice and corn have a lower content. Oat prolamins(avenins) have an intermediate content of those aminoacids,and a high consumption may be also toxic in CeD(25). Thetoxicity of repetitive glutamine/proline- rich sequences hasbeen demonstrated in vitro in mucosal explant cultures(100,101)

and in vivo in proximal and distal intestine(102).Gluten seems to have a direct effect on the epithelium,

both on enterocytes and on IEL, what could play a role inthe initial bias of the mucosal immune response. The exposureof intestinal biopsies from celiacs to gluten in vitro inducesan increase of HLA-DR expression on enterocytes and laminapropria macrophages in less than an hour(103,104). It is notclear whether the effect on enterocytes is due to a toxicmechanism(74) or whether an aberrant processing pathwayfor gluten exists in those cells in CeD patients(105). Gliadinsprovoke a reorganization of the actin cytoskeleton in healthymucosa, and anti-actin antibodies are found in CeD(106).Regarding IEL, γδ IEL are able to directly recognize nativeunprocessed gluten(107). Finally, gluten activates the alternativecomplement pathway(108). Regardless of these findings,the primary triggering event(s) in CeD remain(s) unknown.

AUTOIMMUNITY IN CELIAC DISEASEActive CeD is characterized by the presence of serum anti-

endomysial IgA antibodies (EMA). These antibodies providethe screening diagnosis of CeD with a sensitivity and specificity


318


close to 100%(109). And CeD has a high rate of associationwith other autoimmune disorders such as Type I DiabetesMellitus, Dermatitis Herpetiformis, autoimmune thyroiditis,vasculitis, autoimmune alopecia and hepatitis, etc., which arealso unusually frequent in relatives of CeD patients(110).

All in all, the risk of autoimmunity for untreated celiacsis >30% after 20 years, for only 5% in celiacs treated by 2years of age(111). This fact suggests that active CeD conferssusceptibility, by unknown mechanisms, to organ-specificautoimmunity, stressing the relevance of an early diagnosisand GFD.

TISSUE TRANSGLUTAMINASE AND ANTI-TTGAUTOANTIBODIES

Tissue transglutaminase (tTG) is an ubiquitous enzymethat catalyzes covalent bonds between the g-carboxyl groupof glutamine and the amino group of lysine(10,112). tTG isnormally intracellular, being more abundant in fibroblasts,mononuclear cells and endothelium. It has a double physiologicfunction, being involved in apoptosis and in tissue repair.On one hand, it prevents the extra-cellular release of cytoplasmicmaterial during apoptosis by means of stabilizing it throughcovalent bonds(113). On the other hand, if tTG is releasedfrom the cell, it contributes to the assembly of extra-cellularmatrix during tissue repair.

In non-physiologic situations in which there is an excessof glutamyl-donor molecules with respect to receptormolecules, tTG can catalyze the deamidation of glutamineinto glutamic acid. And, interestingly, gliadins, with over30% content in glutamine, are important sources of glutamylgroups(10,96). The connection between tTG and CeD may beinferred from the fact that deamidation of gluten peptidesin vitro renders them more immunogenic(114-116) and amenableof enhanced presentation at the HLA-DQ2/8 bindingpocket(117-119), though deamidation is not an absoluterequirement(14,17).

The determination of endomysial IgA antibodies (EMA)by immuno-fluorescence became the gold standard forthe screening of celiac disease, but is a time-consuming andsubjective technique(56). For these reasons, the identificationof tTG as the main(11) (though not only(120)) auto-antigen ofEMA antibodies represented a break-through, since it allowedfor the development of objective and standardized solidphase assays such as enzyme-linked immuno-sorbent assay(ELISA)(121,122).

The current model for the role of tTG is as follows(Fig. 6)(124,125): tTG would deamidate gluten peptides andgenerate neo-epitopes (and gluten-tTG complexes) thatwould be presented by HLA-DQ2 or DQ8 to lamina propria

lymphocytes (LPL)(118). The production of autoantibodies(126)

may be due to the recognition of the neo-epitopes by intestinalBc, that can also act as APC by means of their HLA-DQ2expression(123). LPL would become activated after recognitionof gluten peptides in DQ2 and could provide help to B cells,allowing for the expansion of the auto-reactive clones. Thereare evidences to support these hypothesis, such as an increasein expression(127) and activity(10) of tTG in CeD mucosa (alsoduring GFD), or the isolation of HLA-DQ-2-restrictedLPL Tc clones with specificity for deamidated gluten(12),though the model is not formally proven to date.

The role of anti-tTG antibodies in the pathogenesis ofCeD is not clear either, though they are generally consideredan epiphenomenon rather than pathogenic(128,129). Anti-tTG antibodies are able to block the activity of tTG in vitro(130,131),but the net effect of this blockade in vivo is unknown: itmight be beneficial by decreasing the generation of glutenneo-epitopes(118,132), but it could also be detrimental byinhibiting the synthesis of TGF-β, an important mediatorof mucosal healing(133) in whose biosynthesis tTG plays akey role(130,134).

INTRAEPITHELIAL LYMPHOCYTES IN CELIAC DISEASE

The immune response to gliadins takes place at thelamina propria and epithelial levels. The role of laminapropria lymphocytes, LPL, seems clearer than that ofintraepithelial lymphocytes (IEL), despite the fact that thevariations in IEL subsets and their global increase are aconstant feature of CeD. Indeed, the first detectable abnormalityin CeD is an increase in αβ and γδ IEL(75,135), what was alsothe first histopathologic feature described(101). The increasedIEL % in the epithelium is due both to their increasedproliferation and to a reduction in epithelial cells duringthe flat mucosa stage of CeD(136,137). The increase in T or CD3+

IEL is also the first detectable event during the glutenchallenge test.

A second abnormality observed in CeD, which turnedout to be nearly pathognomonic, is the increase in TcR-γδ+

IEL(9,138), determined initially by immuno-histochemistry(139-

141) and subsequently quantified by flow-cytometry (137).Both αβ and γδ IEL proliferate in situ in CeD(142). However,while the increase in αβ IEL correlates with disease activity(137)

and is corrected by the GFD, the increase in γδ IEL is constantin relative terms: while these cells average 4% of all IEL inhealthy controls, they represent a 25% in celiacs(137), in allphases of disease. The γδ IEL increase is not totally specificof CeD, since it has been occasionally found in other situations,such as cow’s milk intolerance, food allergy(140),


319


cryptosporidiasis(140), giardiasis(140,144), Sjögren Syndrome(145)

and IgA deficiency(146). However, the increase in γδ IEL in aminority of patients with these conditions tends to bemild and transient(143) or in some cases may correspond tolatent CeD. The γδ IEL increase is not observed in othercommon intestinal disorders(147), and it can be stated thatCeD is the only disease in which γδ IEL are increasedsystematically, permanently and intensely(139-141). Besides,the increase in γδ IEL is observed in all phases of the disease(even in GD) (Fig. 7), what makes this parameter a helpfuldiagnostic tool in latent and potential CeD(137).

The third and last abnormality described in IEL subsetsin CeD is the profound decrease in CD3- CD103+ IEL(138), alsotermed «NK-like» IEL. The combined determination of gdand CD3- IEL provides specificity to the pathology study inCeD(137). The NK-like or CD3- IEL subset is best studied byflow-cytometry(148,149), given the need for multi-color stainingsince these cells possess no specific markers. CD3- IEL arenumerically the second subset in the healthy small bowel:50.25±2.57% in children < 3 years, 28.28±2.23% in >3 year-old subjects (mean±SD) and they become virtually undetectablein active CeD (Fig. 7). There are several sub-populations

Figure 7. IEL changes along the course ofCeliac Disease. The first abnormality detectedin the mucosa of CD patients, even prior tohistologic or antibody findings, is an increasein TcR-γδ IEL, practically pathognomonic ofCD. When exposure to gluten stimulates theimmune system of the gut, TcR ab IEL increasein numbers and activation markers, and CD3-

(NK and NK-like) IEL literally vanish. Thesetwo parameters, unlike the increase in γδIEL, tend to normalize during Gluten Free Diet(GFD). Subsequently, lamina propria CD4+

Tc increase and get activated and contributeto induce the rest of the pathogenic pathwayleading to mucosal atrophy. The changes inIEL subsets are very characteristic of CD andthe IEL «lymphogram» has a high sensitivityand specificity in the diagnosis of CD, even ofatypical forms (potential, latent).

Figure 6. Pathogenic model of CeliacDisease. Gliadin peptides get access to themucosal immune system of the small bowel andundergo deamidation by tissue transglutaminase(tTG), extracellularly or in lamina propriaAPC. The peptides are then presented by APCin HLA-DQ2 or DQ8 to CD4+ Tc, whichproduce Th1 cytokines such as INF-γ and TNF-α. These pro-inflammatory cytokines inducean increased production of matrix metallo-proteases and contribute to epithelial apoptosis.Epithelial cell death is likely predominantlyinduced by NK-receptor-bearing intra-epitheliallymphocytes (IEL) that exert cytolytic actionsvia recognition of non classic MHC on enterocytesthat produce the stimulating cytokine IL-15,closing in the pathogenic circle. Lamina propriaCD4+ Tc can also stimulate Bc production ofantibodies such as anti-tTG or anti-gliadinAbs.


320


within CD3- IEL: Tc precursors (more abundant in very youngchildren); the most prevalent true NK cells(149) (with decreasingnumbers with age); and, occasionally, oligoclonal pre-malignant CD3- IEL in refractory CeD (in elderly individualsmainly)(177). The physiologic role of CD3- IEL is unknown,though for NK IEL is likely related to their cytotoxic capacity(149).The reasons for their disappearance from the epithelium atall phases of active CeD (including latent and potential,though they re-appear on GFD)(136) are also unclear. Theanalysis by flow-cytometry of the 3 parameters (αβ, γδ andCD3- IEL), termed «IEL lymphogram» (Fig. 7) has a highspecificity and sensitivity in the clinics in the diagnosis ofCeD, and is particularly helpful in atypical presentations(178).

CURRENT PATHOGENIC MODEL OF CELIAC DISEASEThe current most accepted view of the pathogenesis of

CeD is as follows(Fig. 6): Gluten would gain access to thePeyer’s patches physiologically via M cells, or supra-physiologically during periods of increased epithelialpermeability(150). Gluten would be processed by Peyer’spatches dendritic cells(179) and presented to CD4+ Tc(151). Inthe absence of deamidation, the presentation of glutenpeptides on HLA-DQ2 or DQ8 would induce a Th2response(152). However, in the presence of tTG activity anddeamidation of gluten peptides in the antigen-presentingcells, with enhanced avidity for DQ2/DQ8, the responsewould be biased towards Th1. IEL, which produce Th1cytokines(180), could also predispose the initial response togluten under certain conditions, such as infections. Presentationof gluten to Tc could be carried out not only by dendriticcells(153-155), but also by macrophages, Bc and even enterocytes,that express HLA class II(156). Enterocytes can present antigensto LPL via evaginations through the basement membrane(157),and can express costimulatory molecules under inflammatoryconditions(158-160). The primed CD4+ Tc would then recirculateto the lamina propria(161,162), and subsequent contact withgluten would induce their activation(135) and proliferation(75),with production of pro-inflammatory cytokines such asTNF-α(163,164). This would result in synthesis and release ofmetalloproteases MMP-1 y MMP-3(165-167) and of KeratinocyteGrowth Factor by stromal cells(168), what would inducecryptal hyperplasia(101,169) (Fig. 6).

The next stage, villous atrophy (Figs. 3-5), would be(at least partially) due to enterocyte death induced byIEL(129,170,171). CD8+ IEL from CeD patients have been shownto respond to gluten peptides presented by HLA-A2(172).Additionally, there is an over-expression of membrane-bound IL-15 on enterocytes in active CeD and refractorysprue(173), what induces the expression of the NK receptors

CD94(174) and NKG2D by CD3+ IEL. The ligand for NKG2D,MIC-A (a non-classical HLA class I molecule) is over-expressed on enterocytes in active CeD, what supportsthe involvement of the MIC-A / NKG2D pathway in theepithelial atrophy of CeD(175, 176) (Fig. 6).

FRONTIERS IN CELIAC DISEASE RESEARCHThe basic knowledge of the pathogenesis of CeD should

be translated into therapeutic alternatives to the gluten-freediet. One of those under research is the possibility of eliminatingthe toxic gluten 33-mer peptidic sequence, what has beenachieved in vitro and in vivo by exposure to bacterial prolylendopeptidases, that have been proposed as an oral therapy(18).Another approach is the inhibition of tTG, but it is unclearhow that would interfere with important physiologic processes.Yet another alternative is the genetic modification of glutento eliminate the toxic sequences in the gliadins, but suchsequences exist also in glutenins, which are essential to thedietary properties of cereals.

Finally, a number of basic questions remain to be answered:What factors other than HLA are needed in order to initiatethe disease? Genetic factors or of other nature (infection,gluten over-exposure, age of its dietary introduction)?. Whatis the role of IEL subsets in CeD?.

In summary, CeD is an autoimmune or auto-aggressivedisease in which an autoantigen and an HLA-restrictionhave been found, but it remains orphan of therapeuticapproaches. Further research is needed to define themechanisms that lead to absence of immunologic toleranceto gluten, and to develop potential strategies to restore it.

CORRESPONDENCE TO: Francisco LeónClinical Discovery-Immunology Pharmaceutical Research Institute Bristol-Myers SquibbRt. 206 and Province Line Rd.Princeton, NJ 08543Phone: 609-252-6254. Fax: 609-252-6816E-mail: [email protected]

REFERENCES1. Gee SJ. On the coeliac affection. St. Bartholomew´s Hospital Reports

1888;17-20.2. Dicke WK, Weijers HA, Van De Kamer JH. Coeliac disease. II. The

presence in wheat of a factor having a deleterious effect in casesof coeliac disease. Acta Paediatr 1953;42:34-42.

3. Royer M, Croxatto O, Biempica L, Balcazar Morrison AJ. [Duodenalbiopsy by aspiration under radioscopic control]. Prensa MedArgent 1955;42:2515-2519.


321


4. Crosby WH, Kugler HW. Intraluminal biopsy of the small intestine;the intestinal biopsy capsule. Am J Dig Dis 1957;2:236-241.

5. Sakula J, Shiner M. Coeliac disease with atrophy of the small-intestine mucosa. Lancet 1957;273:876-877.

6. Chorzelski TP, Beutner EH, Sulej J, Tchorzewska H, Jablonska S,Kumar V, et al. IgA anti-endomysium antibody. A newimmunological marker of dermatitis herpetiformis and coeliacdisease. Br J Dermatol 1984;111:395-402.

7. Catassi C, Ratsch IM, Fabiani E, Rossini M, Bordicchia F, CandelaF, et al. Coeliac disease in the year 2000: exploring the iceberg.Lancet 1994;343:200-203.

8. Sollid L M, Markussen G, Ek J, Gjerde H, Vartdal F, Thorsby E.Evidence for a primary association of celiac disease to a particularHLA-DQ alpha/beta heterodimer. J Exp Med 1989;169:345-350.

9. Spencer J, Isaacson PG, Diss TC, MacDonald TT. Expression ofdisulfide-linked and non-disulfide-linked forms of the T cellreceptor gamma/delta heterodimer in human intestinal intraepitheliallymphocytes. Eur J Immunol. 1989;19:1335-1338.

10. Bruce SE, Bjarnason I, Peters TJ. Human jejunal transglutaminase:demonstration of activity, enzyme kinetics and substrate specificitywith special relation to gliadin and coeliac disease. Clin Sci (Lond)1985;68:573-579.

11. Dieterich W, Ehnis T, Bauer M, Donner P, Volta U, Riecken EO,et al. Identification of tissue transglutaminase as the autoantigenof celiac disease. Nat Med 1997;3:797-801.

12. Molberg O, Kett K, Scott H, Thorsby E, Sollid LM, Lundin KE.Gliadin specific, HLA DQ2-restricted T cells are commonly foundin small intestinal biopsies from coeliac disease patients, but notfrom controls. Scand J Immunol 1997;46:103-109.

13. Molberg O, McAdam S, Lundin KE, Kristiansen C, Arentz-HansenH, Kett K, et al. T cells from celiac disease lesions recognize gliadinepitopes deamidated in situ by endogenous tissue transglutaminase.Eur J Immunol 2001;31:1317-1323.

14. Gjertsen HA, Lundin KE, Sollid LM, Eriksen JA, Thorsby E. T cellsrecognize a peptide derived from alpha-gliadin presented by theceliac disease-associated HLA-DQ (alpha 1*0501, beta 1*0201)heterodimer. Hum Immunol 1994;39:243-252.

15. Shidrawi RG, Day P, Przemioslo R, Ellis HJ, Nelufer JM, CiclitiraP J. In vitro toxicity of gluten peptides in coeliac disease assessedby organ culture. Scand J Gastroenterol 1995;30:758-763.

16. Lundin KE, Sollid LM, Anthonsen D, Noren O, Molberg O, ThorsbyE, et al. Heterogeneous reactivity patterns of HLA-DQ-restricted,small intestinal T-cell clones from patients with celiac disease.Gastroenterology 1997;112:752-759.

17. van de WY, Kooy YM, van Veelen PA, Pena SA, Mearin LM,Molberg O, et al. Small intestinal T cells of celiac disease patientsrecognize a natural pepsin fragment of gliadin. Proc Natl AcadSci USA 1998;95:10050-10054.

18. Shan L, Molberg O, Parrot I, Hausch F, Filiz F, Gray GM, et al.Structural basis for gluten intolerance in celiac sprue. Science 2002;297:2275-2279.

19. Mowat AM. Coeliac disease--a meeting point for genetics,immunology, and protein chemistry. Lancet 2003;361:1290-1292.

20. Walker-Smith JA. Celiac Disease. Walker, Durie, Hamilton, Walker-Smith, Watkins. Pediatric Gastrointestinal Disease. Pathophysiology,Diagnosis, Management. Ontario: BC Decker Inc; 2000.

21. Ciclitira PJ, King AL, Fraser JS. AGA technical review on Celiac

Sprue. American Gastroenterological Association. Gastroenterology2001;120:1526-1540.

22. Fasano A. Celiac disease: the past, the present, the future. Pediatrics2001;107:768-770.

23. Jennings JS; Howdle PD. Celiac disease. Curr Opin Gastroenterol2001;17:118-126.

24. Maki M; Collin P. Coeliac disease. Lancet 1997;349:1755-1759.25. Janatuinen EK, Kemppainen TA, Julkunen RJ, Kosma VM, Maki

M, Heikkinen M, et al. No harm from five year ingestion of oatsin coeliac disease. Gut 2002;50:332-335.

26. Barry RE, Baker P, Read AE. Coeliac disease. The clinical presentation.Clin Gastroenterol 1974;3:55-69.

27. Howdle PD. Coeliac Disease in adults. Marsh MN. Coeliac Disease.Oxford: Blackwell Scientific Publications 1992;49-80.

28. Hin H, Bird G, Fisher P, Mahy N, Jewell D. Coeliac disease inprimary care: case finding study. BMJ 1999;318:164-167.

29. Weile B, Cavell B, Nivenius K, Krasilnikoff PA. Striking differencesin the incidence of childhood celiac disease between Denmarkand Sweden: a plausible explanation. J Pediatr Gastroenterol Nutr1995;21:64-68.

30. Catassi C, Fabiani E, Ratsch IM, Coppa GV, Giorgi PL, PierdomenicoR, et al. The coeliac iceberg in Italy. A multicentre antigliadinantibodies screening for coeliac disease in school-age subjects.Acta Paediatr (Suppl) 1996;412:29-35.

31. Csizmadia CG, Mearin ML, von Blomberg BM, Brand R, Verloove-Vanhorick SP. An iceberg of childhood coeliac disease in theNetherlands. Lancet 1999;353:813-814.

32. Not T, Horvath K, Hill I D, Partanen J, Hammed A, Magazzu G,et al. Celiac disease risk in the USA: high prevalence ofantiendomysium antibodies in healthy blood donors. Scand JGastroenterol 1998;33:494-498.

33. Gillett PM, Gillett HR, Israel DM, Metzger DL, Stewart L, ChanoineJP, et al. High prevalence of celiac disease in patients with type1 diabetes detected by antibodies to endomysium and tissuetransglutaminase. Can J Gastroenterol 2001;15:297-301.

34. Ferguson A, Arranz E, O'Mahony S. Clinical and pathologicalspectrum of coeliac disease--active, silent, latent, potential. Gut1993;34:150-151.

35. Catassi C, Ratsch IM, Gandolfi L, Pratesi R, Fabiani E, El AsmarR, et al. Why is coeliac disease endemic in the people of the Sahara?Lancet 1999;354:647-648.

36. Gandolfi L, Pratesi R, Cordoba JC, Tauil PL, Gasparin M, CatassiC. Prevalence of celiac disease among blood donors in Brazil. AmJ Gastroenterol 2000;95:689-692.

37. Sher KS, Fraser RC, Wicks AC, Mayberry JF. High risk of coeliacdisease in Punjabis. Epidemiological study in the south Asian andEuropean populations of Leicestershire. Digestion 1993;54:178-182.

38. Ascher H, Holm K, Kristiansson B, Maki M. Different featuresof coeliac disease in two neighbouring countries. Arch Dis Child1993;69:375-380.

39. Kolho KL, Farkkila MA, Savilahti E. Undiagnosed coeliac diseaseis common in Finnish adults. Scand J Gastroenterol 1998;33:1280-1283.

40. Cook DN, Prosser DM, Forster R, Zhang J, Kuklin NA, AbbondanzoS J, et al. CCR6 mediates dendritic cell localization, lymphocytehomeostasis, and immune responses in mucosal tissue. Immunity2000;12:495-503.


322


41. Bottaro G, Failla P, Rotolo N, Sanfilippo G, Azzaro F, Spina M,et al. Changes in coeliac disease behaviour over the years. ActaPaediatr 1993;82:566-568.

42. Hovdenak N, Hovlid E, Aksnes L, Fluge G, Erichsen MM, Eide J.High prevalence of asymptomatic coeliac disease in Norway: astudy of blood donors. Eur J Gastroenterol Hepatol 1999;11:185-187.

43. Trevisiol C, Not T, Berti I, Buratti E, Citta A, Neri E, et al. Screeningfor coeliac disease in healthy blood donors at two immuno-transfusion centres in north-east Italy. Ital J Gastroenterol Hepatol1999;31:584-586.

44. Maki M, Mustalahti K, Kokkonen J, Kulmala P, Haapalahti M,Karttunen T, et al. Prevalence of Celiac disease among childrenin Finland. N Engl J Med 2003;348:2517-2524.

45. Walker-Smith JA. Celiac disease and Down syndrome. J Pediatr2000;137:743-744.

46. Zubillaga P, Vitoria JC, Arrieta A, Echaniz P, Garcia-MasdevallM D. Down's syndrome and celiac disease. J Pediatr GastroenterolNutr 1993;16:168-171.

47. Hansson T, Anneren G, Sjoberg O, Klareskog L, Dannaeus A.Celiac disease in relation to immunologic serum markers, traceelements, and HLA-DR and DQ antigens in Swedish children withDown syndrome. J Pediatr Gastroenterol Nutr 1999;29:286-292.

48. Mawhinney H, Tomkin GH. Gluten enteropathy associated withselective IgA deficiency. Lancet 1971;2:121-124.

49. Vitoria J C, Arrieta A, Astigarraga I, Garcia-Masdevall D, Rodriguez-Soriano J. Use of serological markers as a screening test infamily members of patients with celiac disease. J Pediatr GastroenterolNutr 1994;19:304-309.

50. Maki M, Hallstrom O, Vesikari T, Visakorpi JK. Evaluation of aserum IgA-class reticulin antibody test for the detection of childhoodceliac disease. J Pediatr 1984;105:901-905.

51. Volta U, Lenzi M, Lazzari R, Cassani F, Collina A, Bianchi FB, etal. Antibodies to gliadin detected by immunofluorescence and amicro-ELISA method: markers of active childhood and adultcoeliac disease. Gut 1985;26:667-671.

52. Chan KN, Phillips AD, Mirakian R, Walker-Smith JA. Endomysialantibody screening in children. J Pediatr Gastroenterol Nutr1994;18:316-320.

53. Grodzinsky E, Jansson G, Skogh T, Stenhammar L, Falth-MagnussonK. Anti-endomysium and anti-gliadin antibodies as serologicalmarkers for coeliac disease in childhood: a clinical study to developa practical routine. Acta Paediatr 1995;84:294-298.

54. Vogelsang H, Genser D, Wyatt J, Lochs H, Ferenci P, GranditschG, et al. Screening for celiac disease: a prospective study on thevalue of noninvasive tests. Am J Gastroenterol 1995;90:394-398.

55. Hansson T, Dannaeus A, Kraaz W, Sjoberg O, Klareskog L.Production of antibodies to gliadin by peripheral blood lymphocytesin children with celiac disease: the use of an enzyme-linkedimmunospot technique for screening and follow-up. Pediatr Res1997;41:554-559.

56. Roldan MB, Barrio R, Roy G, Parra C, Alonso M, Yturriaga R, etal. Diagnostic value of serological markers for celiac disease indiabetic children and adolescents. J Pediatr Endocrinol Metab1998;11:751-756.

57. Guix M, Skinner JM, Whitehead R. Measuring intraepitheliallymphocytes, surface area, and volume of lamina propria in thejejunal mucosa of coeliac patients. Gut 1979;20:275-278.

58. Marsh MN. Studies of intestinal lymphoid tissue. III. Quantitativeanalyses of epithelial lymphocytes in the small intestine of humancontrol subjects and of patients with celiac sprue. Gastroenterology1980;79:481-492.

59. Butterworth CE Jr, Pérez-Santiago E. Jejunal biopsies in sprue.Ann Intern Med 1958;48:8-29.

60. MacDonald TT, Bajaj-Elliott M, Pender SL. T cells orchestrate intestinalmucosal shape and integrity. Immunol Today 1999;20:505-510.

61. Chan KN, Phillips AD, Walker-Smith JA, Koskimies S, Spencer J.Density of gamma/delta T cells in small bowel mucosa related toHLA-DQ status without coeliac disease. Lancet 1993;342:492-493.

62. Manuel PD, Walker-Smith JA, France NE. Patchy enteropathyin childhood. Gut 1979;20:211-215.

63. Revised criteria for diagnosis of coeliac disease. Report of WorkingGroup of European Society of Paediatric Gastroenterology andNutrition. Arch. Dis Child 1990;65:909-911.

64. Faulkner-Hogg KB, Selby WS, Loblay RH. Dietary analysis insymptomatic patients with coeliac disease on a gluten-free diet:the role of trace amounts of gluten and non-gluten food intolerances.Scand J Gastroenterol 1999;34:784-789.

65. Cellier C, Delabesse E, Helmer C, Patey N, Matuchansky C,Jabri B, et al. Refractory sprue, coeliac disease, and enteropathy-associated T-cell lymphoma. French Coeliac Disease Study Group.Lancet 2000;356:203-208.

66. Ryan BM, Kelleher D. Refractory celiac disease. Gastroenterology2000;119:243-251.

67. Ventura A, Magazu G, Gerarduzzi T, Greco L. Coeliac diseaseand the risk of autoimmune disorders. Gut 2002;51:897-898.

68. Martinelli P, Troncone R, Paparo F, Torre P, Trapanese E, FasanoC, et al. Coeliac disease and unfavourable outcome of pregnancy.Gut 2000;46:332-335.

69. Ludvigsson JF, Ludvigsson J. Coeliac disease in the father affectsthe newborn. Gut 2001;49:169-175.

70. Holmes GK, Prior P, Lane MR, Pope D, Allan RN. Malignancyin coeliac disease--effect of a gluten free diet. Gut 1989;30:333-338.

71. Biagi F, Lorenzini P, Corazza G R. Literature review on the clinicalrelationship between ulcerative jejunoileitis, coeliac disease,and enteropathy-associated T-cell. Scand J Gastroenterol 2000;35:785-790.

72. Schweizer JJ, Oren A, Mearin ML. Cancer in children with celiacdisease: a survey of the European Society of PaediatricGastroenterology, Hepatology and Nutrition. J Pediatr GastroenterolNutr 2001;33:97-100.

73. Barbeau WE, Novascone MA, Elgert KD. Is celiac disease due tomolecular mimicry between gliadin peptide-HLA class II molecule-T cell interactions and those of some unidentified superantigen?Mol Immunol 1997;34:535-541.

74. Godkin A, Jewell D. The pathogenesis of celiac disease.Gastroenterology 1998;115:206-210.

75. Schuppan D. Current concepts of celiac disease pathogenesis.Gastroenterology 2000;119:234-242.

76. Kagnoff MF, Paterson YJ, Kumar PJ, Kasarda DD, Carbone FR,Unsworth DJ, et al. Evidence for the role of a human intestinaladenovirus in the pathogenesis of coeliac disease. Gut 1987;28:995-1001.

77. Lahdeaho ML, Parkkonen P, Reunala T, Maki M, Lehtinen M.Antibodies to E1b protein-derived peptides of enteric adenovirustype 40 are associated with celiac disease and dermatitis herpetiformis.Clin Immunol Immunopathol 1993;69:300-305.


323


78. Marsh MN. Immunocytes, enterocytes and the lamina propria:an immunopathological framework of coeliac disease. J. R. Coll.Physicians Lond 1983;17:205-212.

79. Ferguson A, MacDonald T T, McClure J P, Holden R J. Cell-mediatedimmunity to gliadin within the small-intestinal mucosa in coeliacdisease. Lancet 1975;1:895-897.

80. Green PH, Jabri B. Coeliac disease. Lancet 2003; 362: 383-391. 81. King AL, Ciclitira PJ. Celiac disease: strongly heritable, oligogenic,

but genetically complex. Mol Genet Metab 2000;71:70-75. 82. Greco L, Romino R, Coto I, Di Cosmo N, Percopo S, Maglio M,

et al. The first large population based twin study of coeliac disease.Gut 2002;50:624-628.

83. Spurkland A, Sollid LM, Polanco I, Vartdal F, Thorsby E. HLA-DR and -DQ genotypes of celiac disease patients serologicallytyped to be non-DR3 or non-DR5/7. Hum Immunol 1992;35:188-192.

84. Tighe MR, Hall MA, Barbado M, Cardi E, Welsh KI, Ciclitira PJ.HLA class II alleles associated with celiac disease susceptibility ina southern European population. Tissue Antigens 1992;40:90-97.

85. Sollid LM, Thorsby E. HLA susceptibility genes in celiac disease:genetic mapping and role in pathogenesis. Gastroenterology1993;105:910-922.

86. Fernandez-Arquero M, Polanco I, Escobar H, Figueredo MA, dela Concha EG, Clerici-Larradet N. HLA-DQ alleles and susceptibilityto celiac disease in Spanish children. Tissue Antigens 1995;45:145-147.

87. Spurkland A, Ingvarsson G, Falk ES, Knutsen I, Sollid LM, ThorsbyE. Dermatitis herpetiformis and celiac disease are both primarilyassociated with the HLA-DQ (alpha 1*0501, beta 1*02) or the HLA-DQ (alpha 1*03, beta 1*0302) heterodimers. Tissue Antigens1997;49:29-34.

88. Djilali-Saiah I, Schmitz J, Harfouch-Hammoud E, Mougenot JF,Bach JF, Caillat-Zucman S. CTLA-4 gene polymorphism is associatedwith predisposition to coeliac disease. Gut 1998;43:187-189.

89. King AL, Moodie SJ, Fraser JS, Curtis D, Reid E, Dearlove AM,et al. CTLA-4/CD28 gene region is associated with geneticsusceptibility to coeliac disease in UK families. J Med Genet2002;39:51-54.

90. Popat S, Hearle N, Hogberg L, Braegger CP, O'Donoghue D, Falth-Magnusson K, et al. Variation in the CTLA4/CD28 gene regionconfers an increased risk of coeliac disease. Ann Hum Genet2002;66:125-137.

91. Greco L, Corazza G, Babron MC, Clot F, Fulchignoni-Lataud MC,Percopo S, et al. Genome search in celiac disease. Am. J Hum Genet1998;62:669-675.

92. Greco L, Babron MC, Corazza GR, Percopo S, Sica R, Clot F, et al.Existence of a genetic risk factor on chromosome 5q in Italiancoeliac disease families. Ann Hum Genet 2001;65:35-41.

93. Liu J, Juo SH, Holopainen P, Terwilliger J, Tong X, Grunn A, etal. Genomewide linkage analysis of celiac disease in Finnishfamilies. Am J Hum Genet 2002;70:51-59.

94. Van De Kamer JH, Weijers HA, Dicke WK. Coeliac disease. IV.An investigation into the injurious constituents of wheat inconnection with their action on patients with coeliac disease. ActaPaediatr 1953;42:223-231.

95. Kagnoff MF. Celiac disease. Yamada T. Testbook of Gastroenterology.Philadelphia, Lippincott 1995;1643-1661.

96. Cornell H, Wieser H, Belitz HD. Characterization of the gliadin-

derived peptides which are biologically active in coeliac disease.Clin Chim Acta 1992;213:37-50.

97. Wieser H. The precipitating factor in coeliac disease. BaillieresClin. Gastroenterol 1995;9:191-207.

98. Molberg O, Solheim FN, Jensen T, Lundin KE, Arentz-Hansen H,Anderson OD, et al. Intestinal T-cell responses to high-molecular-weight glutenins in celiac disease. Gastroenterology 2003;125:337-344.

99. Wieser H. Chemistry of gliadins. Eur J Gastroenterol Hepatol1991;3:102-107.

100.Howdle PD, Ciclitira PJ, Simpson FG, Losowsky MS. Are all gliadinstoxic in coeliac disease? An in vitro study of alpha, beta, gamma,and w gliadins. Scand J Gastroenterol 1984;19:41-47.

101.Marsh MN. Gluten, major histocompatibility complex, and thesmall intestine. A molecular and immunobiologic approach to thespectrum of gluten sensitivity ('celiac sprue'). Gastroenterology1992;102:330-354.

102.Ciclitira PJ, Evans DJ, Fagg NL, Lennox ES, Dowling RH. Clinicaltesting of gliadin fractions in coeliac patients. Clin Sci (Lond) 1984;66:357-364.

103.Fais S, Maiuri L, Pallone F, De Vincenzi M, De Ritis G, TronconeR, et al. Gliadin induced changes in the expression of MHC-class II antigens by human small intestinal epithelium. Organculture studies with coeliac disease mucosa. Gut 1992;33:472-475.

104.Maiuri L, Picarelli A, Boirivant M, Coletta S, Mazzilli MC, DeVincenzi M, et al. Definition of the initial immunologic modificationsupon in vitro gliadin challenge in the small intestine of celiacpatients. Gastroenterology 1996;110:1368-1378.

105.Friis S, Dabelsteen E, Sjostrom H, Noren O, Jarnum S. Gliadinuptake in human enterocytes. Differences between coeliac patientsin remission and control individuals. Gut 1992;33:1487-1492.

106.Clemente MG, Musu MP, Frau F, Brusco G, Sole G, Corazza GR,et al. Immune reaction against the cytoskeleton in coeliac disease.Gut 2000;47:520-526.

107.Klein JR, Hamad M. Gamma delta T cells, antigen recognition andintestinal immunity. Immunol Today 1995;16:108-109.

108.Unsworth DJ, Wurzner R, Brown DL, Lachmann PJ. Extracts ofwheat gluten activate complement via the alternative pathway.Clin Exp Immunol 1993;94:539-543.

109.Corrao G, Corazza GR, Andreani ML, Torchio P, Valentini RA,Galatola G, et al. Serological screening of coeliac disease: choosingthe optimal procedure according to various prevalence values.Gut 1994;35:771-775.

110.Petaros P, Martelossi S, Tommasini A, Torre G, Caradonna M,Ventura A. Prevalence of autoimmune disorders in relatives ofpatients with celiac disease. Dig Dis Sci 2002;47:1427-1431.

111.Ventura A, Magazzu G, Greco L. Duration of exposure to glutenand risk for autoimmune disorders in patients with celiac disease.SIGEP Study Group for Autoimmune Disorders in Celiac Disease.Gastroenterology 1999;117:297-303.

112.Greenberg CS, Birckbichler PJ, Rice RH. Transglutaminases:multifunctional cross-linking enzymes that stabilize tissues. FASEBJ 1991;5:3071-3077.

113.Piacentini M, Colizzi V. Tissue transglutaminase: apoptosis versusautoimmunity. Immunol Today 1999;20:130-134.

114.Johansen BH, Vartdal F, Eriksen JA, Thorsby E, Sollid LM.Identification of a putative motif for binding of peptides to HLA-DQ2. Int Immunol 1996;8:177-182.

115.Bartnes K, Leon F, Briand JP, Travers PJ, Hannestad K. A novel


324


first primary anchor extends the MHC class II I-Ad binding motifto encompass nine amino acids. Int Immunol 1997;9:1185-1193.

116.Moustakas AK, van de WY, Routsias J, Kooy YM, van Veelen P,Drijfhout JW, et al. Structure of celiac disease-associated HLA-DQ8 and non-associated HLA-DQ9 alleles in complex with twodisease-specific epitopes. Int Immunol 2000;12:1157-1166.

117. van de WY, Kooy YM, Drijfhout JW, Amons R, Koning F. Peptidebinding characteristics of the coeliac disease-associated DQ(alpha1*0501,beta1*0201) molecule. Immunogenetics 1996;44:246-253.

118.Molberg O, Mcadam SN, Korner R, Quarsten H, Kristiansen C,Madsen L, et al. Tissue transglutaminase selectively modifiesgliadin peptides that are recognized by gut-derived T cells in celiacdisease. Nat Med 1998;4:713-717.

119.van de WY, Kooy Y, van Veelen P, Pena S, Mearin L, PapadopoulosG, et al. Selective deamidation by tissue transglutaminase stronglyenhances gliadin-specific T cell reactivity. J Immunol 1998;161:1585-1588.

120.Uhlig HH, Lichtenfeld J, Osman AA, Richter T, Mothes T. Evidencefor existence of coeliac disease autoantigens apart from tissuetransglutaminase. Eur J Gastroenterol Hepatol 2000;12:1017-1020.

121.Dieterich W, Laag E, Schopper H, Volta U, Ferguson A, Gillett H,et al. Autoantibodies to tissue transglutaminase as predictors ofceliac disease. Gastroenterology 1998;115:1317-1321.

122.León F, Camarero C, Pena R, Eiras P, Sanchez L, Baragaño M, etal. Anti-transglutaminase IgA ELISA: Clinical potential anddrawbacks in Celiac Disease diagnosis. Scand J Gastroenterol2001;36:849-853.

123.Sollid LM, Molberg O, McAdam S, Lundin KE. Autoantibodiesin coeliac disease: tissue transglutaminase-guilt by association?Gut 1997;41:851-852.

124.Sollid LM. Molecular basis of celiac disease. Annu Rev Immunol2000;18:53-81.

125.van de W Y, Kooy Y, van Veelen P, Vader W, Koning F, Pena S.Coeliac disease: it takes three to tango! Gut 2000;46:734-737.

126.Marzari R, Sblattero D, Florian F, Tongiorgi E, Not T, TommasiniA, et al. Molecular dissection of the tissue transglutaminaseautoantibody response in celiac disease. J Immunol 2001;166:4170-4176.

127.Brusco G, Muzi P, Ciccocioppo R, Biagi F, Cifone MG, CorazzaGR. Transglutaminase and coeliac disease: endomysial reactivityand small bowel expression. Clin Exp Immunol 1999;118:371-375.

128.Biagi F, Parnell ND, Ellis HJ, Ciclitira PJ. Endomysial antibodyproduction is not related to histological damage after in vitro glutenchallenge. Eur J Gastroenterol Hepatol 2000;12:57-60.

129.Maiuri L, Ciacci C, Raia V, Vacca L, Ricciardelli I, Raimondi F, etal. FAS engagement drives apoptosis of enterocytes of coeliacpatients. Gut 2001;48:418-424.

130.Halttunen T, Maki M. Serum immunoglobulin A from patientswith celiac disease inhibits human T84 intestinal crypt epithelialcell differentiation. Gastroenterology 1999;116:566-572.

131.Esposito C, Paparo F, Caputo I, Rossi M, Maglio M, Sblattero D,et al. Anti-tissue transglutaminase antibodies from coeliac patientsinhibit transglutaminase activity both in vitro and in situ. Gut2002;51:177-181.

132.Arentz-Hansen H, Mcadam SN, Molberg O, Fleckenstein B, LundinKE, Jorgensen TJ, et al. Celiac lesion T cells recognize epitopesthat cluster in regions of gliadins rich in proline residues.Gastroenterology 2002;123:803-809.

133.Dignass AU, Podolsky DK. Cytokine modulation of intestinalepithelial cell restitution: central role of transforming growth factorbeta. Gastroenterology 1993;105:1323-1332.

134.Nunes I, Gleizes PE, Metz CN, Rifkin DB. Latent transforminggrowth factor-beta binding protein domains involved in activationand transglutaminase-dependent cross-linking of latent transforminggrowth factor-beta. J Cell Biol 1997;136:1151-1163.

135.Halstensen TS, Scott H, Fausa O, Brandtzaeg P. Gluten stimulationof coeliac mucosa in vitro induces activation (CD25) of laminapropria CD4+ T cells and macrophages but no crypt-cell hyperplasia.Scand J Immunol 1993;38:581-590.

136.Eiras P, Roldan E, Camarero C, Olivares F, Bootello A, Roy G.Flow cytometry description of a novel CD3-/CD7+ intraepitheliallymphocyte subset in human duodenal biopsies: potential diagnosticvalue in coeliac disease. Cytometry 1998;34:95-102.

137.Camarero C, Eiras P, Asensio A, Leon F, Olivares F, Escobar H,et al. Intraepithelial lymphocytes and coeliac disease: permanentchanges in CD3-/CD7+ and T cell receptor gammadelta subsetsstudied by flow cytometry. Acta Paediatr 2000;89:285-290.

138.Spencer J, MacDonald TT, Diss TC, Walker-Smith JA, Ciclitira PJ,Isaacson PG. Changes in intraepithelial lymphocyte subpopulationsin coeliac disease and enteropathy associated T cell lymphoma(malignant histiocytosis of the intestine). Gut 1989;30:339-346.

139.Savilahti E, Arato A, Verkasalo M. Intestinal gamma/delta receptor-bearing T lymphocytes in celiac disease and inflammatory boweldiseases in children. Constant increase in celiac disease. PediatrRes 1990;28:579-581.

140.Spencer J, Isaacson PG, MacDonald TT, Thomas AJ, Walker-SmithJ A. Gamma/delta T cells and the diagnosis of coeliac disease.Clin Exp Immunol 1991;85:109-113.

141.Holm K, Maki M, Savilahti E, Lipsanen V, Laippala P, KoskimiesS. Intraepithelial gamma delta T-cell-receptor lymphocytes andgenetic susceptibility to coeliac disease. Lancet 1992;339:1500-1503.

142. Halstensen TS, Brandtzaeg P. Activated T lymphocytes in the celiaclesion: non-proliferative activation (CD25) of CD4+ alpha/beta cellsin the lamina propria but proliferation (Ki-67) of alpha/beta andgamma/delta cells in the epithelium. Eur J Immunol 1993;23:505-510.

143.Kokkonen J, Holm K, Karttunen TJ, Maki M. Children with untreatedfood allergy express a relative increment in the density of duodenalgammadelta+ T cells. Scand J Gastroenterol 2000;35:1137-1142.

144.Nilssen DE, Halstensen TS, Froland SS, Fausa O, Brandtzaeg P.Distribution and phenotypes of duodenal intraepithelial gamma/deltaT cells in patients with various types of primary B-cell deficiency.Clin Immunol Immunopathol 1993;68:301-310.

145.Iltanen S, Rantala I, Laippala P, Holm K, Partanen J, Maki M.Expression of HSP-65 in jejunal epithelial cells in patients clinicallysuspected of coeliac disease. Autoimmunity 1999;31:125-132.

146.Nilssen DE, Aukrust P, Froland SS, Muller F, Fausa O, HalstensenTS, et al. Duodenal intraepithelial gamma/delta T cells and solubleCD8, neopterin, and beta 2-microglobulin in serum of IgA-deficientsubjects with or without IgG subclass deficiency. Clin Exp Immunol1993;94:91-98.

147.Trejdosiewicz LK, Calabrese A, Smart CJ, Oakes DJ, HowdleP D, Crabtree JE, et al. Gamma delta T cell receptor-positivecells of the human gastrointestinal mucosa: occurrence andV region gene expression in Heliobacter pylori-associatedgastritis, coeliac disease and inflammatory bowel disease.Clin Exp Immunol 1991;84:440-444.

148.Eiras P, Leon F, Camarero C, Lombardia M, Roldan E, Bootello


325


A, et al. Intestinal intraepithelial lymphocytes contain a CD3- CD7+

subset expressing natural killer markers and a singular pattern ofadhesion molecules. Scand J Immunol 2000;52:1-6.

149.Leon F, Roldan E, Sanchez L, Camarero C, Bootello A, Roy G.Human small-intestinal epithelium contains functional naturalkiller lymphocytes. Gastroenterology 2003;125:345-356.

150.Sugi K, Musch MW, Field M, Chang EB. Inhibition of Na+,K+-ATPase by interferon gamma down-regulates intestinal epithelialtransport and barrier function. Gastroenterology 2001;120:1393-1403.

151.Nagata S, McKenzie C, Pender SL, Bajaj-Elliott M, Fairclough PD,Walker-Smith JA, et al. Human Peyer's patch T cells are sensitizedto dietary antigen and display a Th cell type 1 cytokine profile. JImmunol 2000;165:5315-5321.

152.Anderson RP, Degano P, Godkin AJ, Jewell DP, Hill AV. In vivoantigen challenge in celiac disease identifies a single transglutaminase-modified peptide as the dominant A-gliadin T-cell epitope. NatMed 2000;6:337-342.

153.Kelsall B L, Strober W. Distinct populations of dendritic cells arepresent in the subepithelial dome and T cell regions of the murinePeyer's patch. J Exp Med 1996;183:237-247.

154.Alpan O, Rudomen G, Matzinger P. The role of dendritic cells, Bcells, and M cells in gut-oriented immune responses. J Immunol2001;166:4843-4852.

155.Iwasaki A, Kelsall BL. Unique functions of CD11b+, CD8 alpha+,and double-negative Peyer's patch dendritic cells. J Immunol2001;166:4884-4890.

156.Martin-Villa JM, Ferre-Lopez S, Lopez-Suarez JC, Corell A, Perez-Blas M, Arnaiz-Villena A. Cell surface phenotype and ultramicroscopicanalysis of purified human enterocytes: a possible antigen-presentingcell in the intestine. Tissue Antigens 1997;50:586-592.

157.Hershberg RM, Mayer LF. Antigen processing and presentationby intestinal epithelial cells - polarity and complexity. ImmunolToday 2000;21:123-128.

158.Ye G, Barrera C, Fan X, Gourley WK, Crowe SE, Ernst PB, et al.Expression of B7-1 and B7-2 costimulatory molecules by humangastric epithelial cells: potential role in CD4+ T cell activation duringHelicobacter pylori infection. J Clin Invest 1997;99:1628-1636.

159.Hershberg RM, Cho DH, Youakim A, Bradley MB, Lee JS, FramsonPE, et al. Highly polarized HLA class II antigen processing andpresentation by human intestinal epithelial cells. J Clin Invest1998;102:792-803.

160.Nakazawa A, Watanabe M, Kanai T, Yajima T, Yamazaki M, OgataH, et al. Functional expression of costimulatory molecule CD86on epithelial cells in the inflamed colonic mucosa. Gastroenterology1999;117:536-545.

161.Arstila T, Arstila TP, Calbo S, Selz F, Malassis-Seris M, Vassalli P,et al. Identical T cell clones are located within the mouse gutepithelium and lamina propia and circulate in the thoracic ductlymph. J Exp Med 2000;191:823-834.

162.Shibahara T, Wilcox JN, Couse T, Madara JL. Characterizationof epithelial chemoattractants for human intestinal intraepitheliallymphocytes. Gastroenterology 2001;120:60-70.

163.Bajaj-Elliott M, Poulsom R, Pender SL, Wathen NC, MacDonaldTT. Interactions between stromal cell--derived keratinocyte growthfactor and epithelial transforming growth factor in immune-mediated crypt cell hyperplasia. J Clin Invest 1998;102:1473-1480.

164.de la Concha EG, Fernandez-Arquero M, Vigil P, Rubio A, MaluendaC, Polanco I, et al. Celiac disease and TNF promoter polymorphisms.Hum Immunol 2000;61:513-517.

165.Pender SL, Tickle SP, Docherty AJ, Howie D, Wathen NC, MacDonaldTT. A major role for matrix metalloproteinases in T cell injury inthe gut. J Immunol 1997;158:1582-1590.

166.Daum S, Bauer U, Foss HD, Schuppan D, Stein H, Riecken EO,et al. Increased expression of mRNA for matrix metalloproteinases-1 and -3 and tissue inhibitor of metalloproteinases-1 in intestinalbiopsy specimens from patients with coeliac disease. Gut 1999;44:17-25.

167.Satsangi J, Chapman RW, Haldar N, Donaldson P, Mitchell S,Simmons J, et al. A functional polymorphism of the stromelysingene (MMP-3) influences susceptibility to primary sclerosingcholangitis. Gastroenterology 2001;121:124-130.

168.Salvati VM, Bajaj-Elliott M, Poulsom R, Mazzarella G, Lundin KE, Nilsen EM, et al. Keratinocyte growth factor and coeliac disease.Gut 2001;49:176-181.

169.Maiuri L, Ciacci C, Auricchio S, Brown V, Quaratino S, Londei M.Interleukin 15 mediates epithelial changes in celiac disease.Gastroenterology 2000;119:996-1006.

170.Moss SF, Attia L, Scholes JV, Walters JR, Holt PR. Increased smallintestinal apoptosis in coeliac disease. Gut 1996; 39: 811-817.

171.Di Sabatino A, Ciccocioppo R, D'Alo S, Parroni R, Millimaggi D,Cifone MG, et al. Intraepithelial and lamina propria lymphocytesshow distinct patterns of apoptosis whereas both populations areactive in Fas based cytotoxicity in coeliac disease. Gut 2001;49:380-386.

172.Gianfrani C, Troncone R, Mugione P, Cosentini E, De Pascale M,Faruolo C, et al. Celiac disease association with CD8+ T cell responses:identification of a novel gliadin-derived HLA-A2-restricted epitope.J Immunol 2003;170:2719-2726.

173.Mention JJ, Ben Ahmed M, Begue B, Barbe U, Verkarre V, AsnafiV, et al. Interleukin 15: a key to disrupted intraepithelial lymphocytehomeostasis and lymphomagenesis in celiac disease. Gastroenterology2003;125:730-745.

174.Jabri B, de Serre NP, Cellier C, Evans K, Gache C, Carvalho C, etal. Selective expansion of intraepithelial lymphocytes expressingthe HLA-E-specific natural killer receptor CD94 in celiac disease.Gastroenterology 2000;118:867-879.

175. Hue S, Mention JJ, Monteiro RC, Zhang S, Cellier C, Schmitz J, etal. A direct role for NKG2D/MICA interaction in villous atrophyduring celiac disease. Immunity. 2004;21:367-377.

176.Meresse B, Chen Z, Ciszewski C, Tretiacova M, Bhagat G, KrauszTN, Raulet DH, Lanier LL, Groh V, Green P, Jabri B. CoordinatedInduction by IL15 of a TCR-Independent NKG2D signaling pathwayconverts CTL into lymphokine-activated killer cells in CeliacDisease. Immunity 2004;21:357-366.

177.Leon F, Roy G. On the complexity of human CD3- IntraepithelialLymphocytes. Gastroenterology 2004;126:1217-1219.

178. León F, Eiras P, Camarero C, Roy G. Intestinal intraepitheliallymphocytes and anti-transglutaminase in a screening algorithmfor Coeliac Disease. Gut 2002;50:740-742.

179.Kelsall BL, Leon F. Involvement of intestinal dendritic cells in oraltolerance, immunity to pathogens, and inflammatory bowel disease.Immunol Rev 2005;206:132-148.

180.León F, Sánchez L, Camarero C, Roy G. Cytokine production byIEL subsets in Celiac Disease. Dig Dis Sci 2005;50:593-600.


immunopathogenesis of celiac disease · ca gastrointestinal más frecuente, afectando al 1% de la...

Documents