The cellular infiltrate of the jejunum in adult coeliac disease and dermatitis herpetiformis following the reintroduction of dietary gluten

The clinical response to gluten challenge: a review of the literature

The aim of this review was to identify, evaluate and summarize all relevant studies reporting on the clinical response to gluten challenge by adult or pediatric patients with suspected or diagnosed coeliac disease (CD) on a gluten-free diet. We evaluated the effect of gluten challenge on changes in symptoms, intestinal mucosa histology, and serum antibodies. A systematic electronic search was performed for studies published as of 1966 using PubMed and Scopus databases. In the reviewed studies, doses ranged from 0.2 to 30 g/day of wheat gluten or comprised a gluten-containing diet. The onset of symptoms upon gluten intake varied largely from days to months and did not parallel serum antibody or histological changes. Within 3 months of gluten challenge, 70%-100% of pediatric CD patients became positive for AGA-IgA and EMA-IgA antibodies and 50%-70% for AGA-IgG. A limited number of trials suggest that no more than half of adult patients developed positive AGA-IgA, EMA-IgA, tTG-IgA or DGP-IgA/IgG titers. Approximately 50%-100% of pediatric and adult patients experienced mucosal relapse of gluten provocation within 3 months, which was preceded by increased mucosal intra-epithelial lymphocytes within several days of challenge. A 3-month high-dose gluten challenge should be suitable to diagnose the majority of CD patients. In some cases prolonged challenge may be needed to verify diagnosis. Combination testing for antibodies and mucosal histology may fasten the diagnosis.

Faecal calprotectin concentrations in untreated coeliac patients

OBJECTIVE

Calprotectin is a granulocyte cytosolic protein that is considered to be a promising marker of subclinical inflammation. High faecal calprotectin concentrations (FCCs) have been found in several intestinal diseases, but no data are currently available on patients with coeliac disease. The purpose of this pilot study was to evaluate FCCs in untreated coeliac patients and to correlate them with clinical score and histological characteristics.

MATERIAL AND METHODS

Twenty-eight consecutive coeliac patients were recruited. Thirty healthy adult volunteers participated as the control group. FCCs were determined by ELISA. Clinical assessment was carried out in all patients. The histological severity of lesions and the infiltration of neutrophil polymorphs in the intestinal mucosa were also evaluated. Mean FCCs in patients and the control group were compared by means of the t-test for independent samples. In coeliac patients, differences in FCCs in subgroups identified by clinical score, lesion severity and neutrophil infiltration were evaluated by the Kruskal-Wallis non-parametric test.

RESULTS

FCCs in untreated coeliac patients were not significantly different from those in controls (p=0.163). Among coeliac patients, FCCs were not significantly different in relation to the level of clinical score, lesion severity or neutrophil infiltration (p=0.92, p=0.96 and p=0.74, respectively).

CONCLUSIONS

This study shows, for the first time, that FCCs in untreated coeliac patients do not differ significantly from those in controls.

T-cell responses and cellular immunity in coeliac disease

Increasing evidence points to a direct role for T cells in the mediation of the coeliac intestinal lesion. There is good evidence for increased local T-cell reactivity, manifest as increased in T-cell activation in the lamina propria and T-cell proliferation in the epithelial compartment. A likely scenario is that gluten elicits antigen-specific responses by lamina propria T helper cells, probably of the Th1 (inflammatory-mediator) subtype, leading to secretion of pro-inflammatory cytokines. Such cytokines may have direct effects on intestinal enterocytes, as well as mediating indirect effects by upregulation of MHC antigens and by enhancing the activity of cytolytic T cells. Although gluten-specific IEL responses have not been demonstrated by intraepithelial T lymphocytes (IELs), increasing evidence suggests that IELs can act as cytolytic effector cells and hence are likely to exert enteropathic effects under the influence of pro-inflammatory cytokines.

The effect of an elemental diet with and without gluten on disease activity in dermatitis herpetiformis

Elemental diets are reported to decrease activity of patients with dermatitis herpetiformis. We tested the hypothesis that gluten, given in addition to an elemental diet, is responsible for the intestinal abnormalities, cutaneous immunoreactant deposition, and skin disease activity in dermatitis herpetiformis. At entry eight patients with dermatitis herpetiformis, who were consuming unrestricted diets, were stabilized on their suppressive medications at dosage levels that allowed individual lesions to erupt. Six patients were then given an elemental diet plus 30 of gluten for 2 weeks, followed by the elemental diet alone for 2 weeks. Conversely, two patients received an elemental diet alone for 2 weeks followed by an elemental diet plus gluten during the final 2 weeks. Small bowel biopsies, skin biopsies, and clinical assessments were done at 0, 2, and 4 weeks. Suppressive medication dose requirement decreased over the 4 weeks by a mean of 66%. Six of eight subjects significantly improved clinically during the gluten-challenge phase of the elemental diet and all were improved at the end of the study. The amount of IgA in perilesional skin did not change significantly, but the amount of C3 increased in five of seven evaluable subjects after gluten challenge. Circulating anti-gluten and anti-endomysial antibodies were not significantly affected by the diets. All subjects completing evaluable small bowel biopsies (seven of seven) demonstrated worsening of their villus architecture (by scanning electron microscopy and intraepithelial lymphocyte counts) during gluten challenge and improvement (six of six subjects) after 2 weeks of elemental dietary intake. We conclude that 1) there is a significant improvement in clinical disease activity on an elemental diet, independent of gluten administration, 2) small bowel morphology improves rapidly on an elemental diet, and 3) complement deposition but neither IgA deposition nor circulating antibody levels correlate with gluten intake. It seems likely that dietary factors other than gluten are important in the pathogenesis of the skin lesions in dermatitis herpetiformis.

Histological changes associated with wheat protein antibodies in the absence of villous atrophy

A retrospective study was conducted to assess the association of alpha-gliadin antibodies with intraepithelial lymphocyte counts. Twelve subjects with apparently normal small intestinal histology and raised alpha-gliadin antibody titres had significantly increased intraepithelial lymphocyte counts (42 (SEM) 5.9) when compared with 16 subjects with normal alpha-gliadin antibody titres (17 (3.2); p less than 0.001). These findings show that in the absence of gross pathology raised alpha-gliadin antibody titres are associated with increased numbers of intraepithelial lymphocytes and may reflect continuous immunological processes in the small intestine.

Timing of infiltration of T lymphocytes induced by gluten into the small intestine in coeliac disease

Jejunal biopsy was performed on control subjects and patients with treated and untreated coeliac disease. Monoclonal antibodies to T lymphocyte surface markers were used to quantify T cell phenotypic subsets in the jejunal mucosa. The patients with untreated coeliac disease had significantly more of both suppressor/cytotoxic and helper/inducer T cells in the surface epithelium than either the control subjects or the treated patients. Serial jejunal biopsy specimens were taken from five treated coeliac patients for six hours after a gluten challenge. In four of these five infiltration of the surface epithelium by both T cell phenotypes, together with deterioration in the villus architecture, had occurred both within two hours of having started the challenge. This suggests that T lymphocytes may have a role in the pathogenesis of coeliac disease.

The immunology of coeliac disease

Coeliac disease is defined as that disorder in which there is an abnormality of the small intestinal mucosa manifested by contact with the gluten of wheat and certain other cereal grains. In the immunological theory of the pathogenesis of coeliac disease, gluten, or a component, is viewed as the antigen responsible for the immune response. The search for the gluten component responsible for 'toxicity' and, by implication, antigenicity, is described. The antigen may be presented differently to the immune system by an abnormal cell membrane, either of the enterocyte, lymphocyte or macrophage. Alternatively, increased amounts of antigen may be absorbed due to increased membrane binding or permeability, either of which could be genetically determined. As a further possibility, coeliac disease may occur because the patients are immunologically hyperresponsive and this too appears to be genetically determined. The perturbations which occur in the mucosal immune system and the systemic immune system are described. It is conceivable that the major complications described (intestinal ulceration, malignancy and splenic atrophy) result from immunological disturbances. The incidence of childhood coeliac disease is declining, which may be due to altered exposure to, or increased protection from, the antigen in infancy, or to changes in environmental factors. The immunological mystery of coeliac disease continues to excite interest and fascination, and has certainly been a stimulus to our deeper understanding of gastrointestinal immunology.

Eosinophils of human colonic mucosa: C3b and Fc gamma receptor expression and phagocytic capabilities

Because little is known about eosinophils of the human intestine, we measured their C3b and Fc gamma receptor expression and phagocytic activity in mucosal suspensions from colon resections for large bowel neoplasms. Enzymatically dissociated suspensions were enriched for eosinophils by countercurrent centrifugation. C3b and Fc gamma receptors were measured by immunofluorescent assays with flow cytometry. Phagocytosis of Escherichia coli ON2 was determined by an in vitro microscopic method. Suspensions of normal tissue from neoplasm resections yielded 1.8 X 10(6) eosinophils/g mucosa, and these cells were more numerous than either macrophages or neutrophils. Fivefold enrichment was achieved by countercurrent centrifugation, and 75% of these cells expressed C3b receptors and 90% expressed Fc gamma receptors. Sixty-seven percent of mucosal eosinophils were phagocytic for E. coli ON2 and ingested a mean of 4.7 bacteria per cell. Eosinophils accounted for more overall phagocytic activity than either neutrophils or macrophages.

Immune disorders of the gastrointestinal tract and liver

Immune disorders of the gastrointestinal tract and hepatobiliary systems comprise a diverse group of illnesses which share in common certain overlapping and yet distinctive expressions of cellular and humoral immunity. As is evident from material contained in this article, controversy and disparate results frequently characterize the study of immune mechanisms in a given disease process. Nonetheless, advances in quantitation of specific immunocyte function and phenotypic expression have greatly facilitated the depth of understanding of the immune process related to these disorders. Challenges for future clinical investigation of these disorders are to characterize cell-specific target antigens to which immunologic attack is directed and to unravel the immunogenetic mechanisms that trigger and direct immune-mediated injury to host tissues. It is anticipated that continued investigation of immune disorders of the gastrointestinal tract and liver will clarify pathogenetic mechanisms and thus permit formulation of rational and effective therapies.

Functional and structural aspects of the epithelial lymphocyte, with implications for coeliac disease and tropical sprue

Epithelial lymphocytes comprise a compartmentalised and specialised population of presumed effector cells which, in general, express the surface phenotypes (Lyt-2+; OX2+; OKT8+) of suppressor/cytolytic (Ts/c) cells. Granular cells within this population (gEL) morphologically resemble the circulating large granular lymphocytes (LGL) which subserve spontaneous (NK) cytolytic activity. Recent in vitro results indicate that gEL can develop this function after prolonged in vitro culture; the relevance of this, in vivo, remains to be decided. EL also appear to be able to mediate ADCC with sIgA against enteric micro-organisms. This is the kind of integrated activity that might be anticipated from local immunocytes within the intestinal mucosa. Other recent work suggests that gEL are not precursors of mucosal mast cells. EL also appear to be capable of inducing Ia-like expression in surface and crypt enterocytes, a property enjoyed both by highly purified Th, but also Ts/c, cells as well. This raises the interesting prospect that enterocytes may display antigen in macrophage-like fashion to other adjacent cells within the inter-epithelial cell spaces. These latter observations might be more consistent with the presence of 'activated' and 'blast-transformed' lymphocytes in such conditions as coeliac disease and tropical sprue. Another emergent view that demands appropriate attention is that the infiltrate of Ts/c cells into surface, and crypt, epithelium of coeliac mucosa does not necessarily cause injury or damage to the jejunal tissues. Nevertheless the role, either primary or secondary, that EL play either in coeliac disease or tropical sprue still remains obscure.

Long-term morphological and immunohistochemical observations on biopsy specimens of small intestine from children with gluten-sensitive enteropathy

Jejunal biopsy specimens from nine Spanish children with gluten-sensitive enteropathy were studied with morphometric and immunohistochemical techniques in three stages of the diseases: the first biopsy was taken for diagnosis, when the child had a gluten-containing diet, the second after gluten withdrawal, and the third biopsy after gluten-provocation. The findings were compared with those in 10 healthy adults. The villous:crypt ratio and the length of the surface epithelium per stretched millimetre muscularis mucosae were decreased, whereas the number of interepithelial lymphocytes per millimetre surface epithelium was increased when the child had a gluten-containing diet. Although these parameters improved after withdrawal of gluten for at least seven months, they never reached the values of the healthy control group. With the indirect immunoperoxidase technique it was shown that the numbers of IgA-, IgG-, and IgM-containing cells, expressed per "mucosal tissue unit" of 4 micrometer thick and 1 mm wide, were significantly increased during the active phases of the disease. This increase was most striking for the IgM-containing cells. The most sensitive parameters for the histological diagnosis of gluten-sensitive enteropathy are the villous:crypt ratio or the length of the surface epithelium per millimetre muscularis mucosae, the number of interepithelial lymphocytes per millimetre surface epithelium, and the number of IgM-containing cells per millimetre muscularis mucosae.

Intraepithelial lymphocytes in the jejunal mucosa of malnourished rats

Intraepithelial lymphocytes (IEL) have been counted in the jejunal mucosa of adult Wistar rats submitted to a protein-free diet for 84 days and of a control group receiving a 20% casein diet, in order to evaluate the effect of protein deprivation. Relative counts (IEL/100 epithelial cells), absolute counts (number of IEL per millimetre of muscularis mucosae), and the proportion of lymphocytes crossing the basement membrane have been evaluated. Both relative and absolute IEL counts were diminished but the proportion of crossing lymphocytes was greatly increased in the malnourished group. The low number of IEL seemed to be related to lymphatic vessel dilatation in the lamina propria. The possibly primary effect of malnutrition on IEL counts in our experimental model and the eventual role of the observed lymphatic dilatation have been discussed.

The metabolism of C3 in adult coeliac disease

To study possible pathogenetic mechanisms in adult coeliac disease, we performed a metabolic investigation of a component (C3) of the most important effector of humoral immunity, the complement system. Purified and biologically active C3 was labelled with 125I and injected together with 131I-labelled albumin into six patients with adult coeliac disease exhibiting different degrees of disease activity. The same labelled preparations were given to 12 normal individuals. Plasma and urine radioactivity were studied for a total of 8 days. Fractional catabolic rates (FCR) and synthesis rates were calculated by the metabolic clearance method. Other mathematical methods were not used because a final straight exponential was not always obtained, probably owing to extravascular sequestration of protein. An increased FCR was found in most patients, with the highest values seen in active, untreated disease. This suggests that activation of complement by immune complexes may be a pathogenetic factor in adult coeliac disease.

Reintroduction of gluten in adults and children with treated coeliac disease

Twenty-eight patients, thought to have coeliac disease and on gluten free diets, were put on a normal diet to confirm their diagnoses. Nineteen had been diagnosed in adult life (ACD) and nine in childhood (CCD). Patients were assessed on jejunal, morphological, and symptomatic parameters. Eighteen patients with ACD relapsed within seven weeks. Nine patients with CCD relapsed at variable times but five took longer than seven weeks, the longest period beint 10 months. Seven patients had no symptoms despite morphological deterioration during challenge and one patient, with ACD, did not relapse and was HLA B8 negative. This patient with ACD had subtotal villous atrophy on two jejunal biopsies and later showed morphological improvement on a gluten free diet. There was no correlation between the relapse time and time spent on a gluten free diet.

Immunologic and gastrointestinal abnormalities in dermatitis herpetiformis

Eighty patients with untreated dermatitis herpetiformis (DH) were studied. The final diagnosis was made after completion of immunofluorescence (IF) studies of the skin, iodine provocation tests and gastrointestinal investigations. IgA deposits in the skin and the HLA-DRw3 B-cell alloantigen can be demonstrated in nearly all cases of DH. Positive iodine provocation test and gastrointestinal abnormalities are present in about 78% of the cases. For diagnostic purposes tissue typing and intestinal biopsy is of value in addition to IF studies of the skin.

Immunoglobulins in the jejunal mucosa in adult coeliac disease and dermatitis herpetiformis after the reintroduction of dietary gluten

Cells containing immunoglobulin (IgA, IgG, IgM) have been measured and the distribution of extracellular and epithelial cell immunoglobulin assessed in treated patients with adult coeliac disease (ACD) and dermatitis herpetiformis (DH) before and after gluten was reintroduced to the diet. Patients with ACD and DH frequently had IgM and IgG cells above the normal range even before re-exposure to gluten, although the range of IgA cells was normal. In both diseases IgA and IgM cells increased after gluten with a proportionally greater rise in the latter, so that numbers of IgM cells, but not of IgA, exceeded the control range in all but one patient. There were increased quantities of IgA and IgM extracellularly in the lamina propria and in epithelial cells after challenge with gluten. Third component of complement was also found in some biopsies after re-exposure to gluten. These findings support the suggestion that gluten induces a humoral immunological response within the small intestinal mucosa and that both IgA and IgM systems are involved.

Complement system studies in adult coeliac disease

Detailed complement system studies were performed in 22 patients with adult coeliac disease. Activation products of C3 were observed in the fresh sera of all untreated patients, while only 4 had activation products of factor B of the alternate pathway. Levels of C4 and C3 were lower than normal mean, but only the depression of C4 reached a level of statistical significance. The amounts of circulating C3 activation products were significantly reduced when the patients were on a gluten-free diet. There is thus evidence that activation of the classical pathway of the complement system takes place in adult coeliac disease, and there is an association between gluten ingestion and the complement activity. We suggest that a possible mechanism of tissue injury in this disease is activation of complement factors by a humoral immune reaction to dietary gluten in the intestinal wall.

Immunological phenomena in the jejunum and serum after reintroduction of dietary gluten in children with treated coeliac disease

Jejunal mucosal immunoglobulin-containing cells of all three major classes (IgA, IgM, IgG) were increased in coeliac children on gluten-containing diets but only IgM cell numbers were raised in those on gluten-free diets. Patients with subtotal villous atrophy had greater numbers of immunoglobulin-containing cells than patients with normal mucosa. In previously treated patients studied before and after three months on a gluten-containing diet ther was an increase in all three classes of cell, IgM containing cells showing the greatest proportional rise. Basement membrane staining with anti-IgA serum occurred in coeliacs and was most intense in untreated patients. Apart from one patient with very low levels of serum IgA, serum immunoglobulins did not differ from normal. However, after reintroduction of gluten to the diet a significant fall in serum IgM concentrations occurred compared with levels in the same patients while on gluten-free diets. It seems probable that both IgA and IgM systems are important in the immunopathogenesis of the small intestinal lesion of childhood coeliac disease.

Cellular infiltrate of the jejunum after re-introduction of dietary gluten in children with treated coeliac disease

Jejunal lamina propria plasma cells and eosinophils and intraepithelial lymphocytes were raised in coeliac children on gluten-containing diets, but only intraepithelial lymphocytes were increased in patients on gluten-free diets. In contrast, lamina propria lymphocytes were reduced in children with coeliad disease on gluten-containing diets but were normal in paitents on gluten-free diets. In children with coeliac disease who were studied serially, lamina propria plasma cells and eosinophils and intraepithelial lymphocytes increased, and lamina propria lymphocytes decreased, within three months of the reintroduction of gluten to the diet. These observations are essentially similar to those made in the adult form of the disease and suggest that more than one type of immunological reaction is involved in the pathogenesis of the jejunal lesion.

T cell depletion in untreated adult coeliac disease

The proportional and absolute numbers of circulating thymus dependent lymphocytes (T cells) were reduced in untreated patients with coeliac disease but were normal after treatment with a gluten free diet. There was an inverse correlation between circulating T cell numbers and jejunal intraepithelial lymphocytes. This evidence suggests a possible role for T cells in the pathogenesis of coeliac disease and is a further example of disturbed cell mediated immunity in this condition.