Intraepithelial gammadelta+ lymphocytes: a comparative study between celiac disease, small intestinal bacterial overgrowth, and irritable bowel syndrome

Show Me What You Have Inside-The Complex Interplay between SIBO and Multiple Medical Conditions-A Systematic Review

The microbiota, as a complex of microorganisms in a particular ecosystem, is part of the wider term-microbiome, which is defined as the set of all genetic content in the microbial community. Imbalanced gut microbiota has a great impact on the homeostasis of the organism. Dysbiosis, as a disturbance in bacterial balance, might trigger or exacerbate the course of different pathologies. Small intestinal bacterial overgrowth (SIBO) is a disorder characterized by differences in quantity, quality, and location of the small intestine microbiota. SIBO underlies symptoms associated with functional gastrointestinal disorders (FGD) as well as may alter the presentation of chronic diseases such as heart failure, diabetes, etc. In recent years there has been growing interest in the influence of SIBO and its impact on the whole human body as well as individual systems. Therefore, we aimed to investigate the co-existence of SIBO with different medical conditions. The PubMed database was searched up to July 2022 and we found 580 original studies; inclusion and exclusion criteria let us identify 112 eligible articles, which are quoted in this paper. The present SIBO diagnostic methods could be divided into two groups-invasive, the gold standard-small intestine aspirate culture, and non-invasive, breath tests (BT). Over the years scientists have explored SIBO and its associations with other diseases. Its role has been confirmed not only in gastroenterology but also in cardiology, endocrinology, neurology, rheumatology, and nephrology. Antibiotic therapy could reduce SIBO occurrence resulting not only in the relief of FGD symptoms but also manifestations of comorbid diseases. Although more research is needed, the link between SIBO and other diseases is an important pathway for scientists to follow.

How to Recognize and Treat Small Intestinal Bacterial Overgrowth?

Small Intestinal Bacterial Overgrowth (SIBO) is a form of dysbiosis that involves increased bacterial colonization of the small intestine with some of the bacteria more characteristic of the colon microbiota. The prevalence of SIBO over recent decades has been estimated to range from 2.5 to 22% (depending on the source) and to increase with age and among individuals with comorbidities. Recently, an increase in the number of diagnosed SIBO cases has been observed, which is primarily due to the availability of noninvasive breath tests that facilitate the diagnostic process. However, SIBO is still both a diagnostic and a therapeutic problem. This review presents the pathophysiology, manifestations, diagnostics, and recommended management of SIBO.

Human Leukocyte Antigen (HLA) Haplotype Does Not Influence the Inflammatory Pattern of Duodenal Lymphocytosis Linked to Irritable Bowel Syndrome

Background and objectives: Duodenal lymphocytosis (DL) is a condition characterized by enhanced infiltration of intraepithelial lymphocytes (IELs) in the duodenal mucosa, and it can be linked to both gluten- and non-gluten-related diseases, such as irritable bowel syndrome (IBS). Materials and methods: We retrospectively selected patients with DL linked to IBS. Formalin-embedded biopsy samples of the duodenum were collected. CD3 lymphocyte immunohistochemistry was used for IELs. The real-time polymerase chain reaction was used to quantify the amount of mRNA coding for tissue transglutaminase 2 (tTG2), interferon-gamma (IFNγ), toll-like receptor 2 (TLR2), and myeloid differentiation primary response 88 (MyD88). All subjects underwent DQ2-8 haplotype analysis. Controls were represented by subjects with IBS without DL. Results: Thirty-two patients with IBS-DL were retrospectively recruited. Fourteen subjects (43.8%) had a DQ2-8 haplotype. DQ2-8 positive subjects had similar levels compared to negative ones for tTG2, IFNγ, TLR2, and MyD88. Cigarette smoke did not influence molecular expression in our study. Smokers had a statistically higher IELs count than non-smokers (54.2 ± 7.7 vs. 36.0 ± 8.8, p < 0.001). A significant, direct correlation between IELs and duodenal expression of IFNγ was found (r = 0.36, p = 0.04). Conclusions: IBS with DL showed higher expression of inflammatory markers than controls, but DQ2-8 haplotype did not seem to affect their expression. Smoking might increase IELs infiltration.

The Influence of Small Intestinal Bacterial Overgrowth in Digestive and Extra-Intestinal Disorders

Small intestinal bacterial overgrowth (SIBO) is a condition hallmarked by an increase in the concentration of colonic-type bacteria in the small bowel. Watery diarrhea, bloating, abdominal pain and distension are the most common clinical manifestations. Additionally, malnutrition and vitamin (B12, D, A, and E) as well as minerals (iron and calcium) deficiency may be present. SIBO may mask or worsen the history of some diseases (celiac disease, irritable bowel disease), may be more common in some extra-intestinal disorders (scleroderma, obesity), or could even represent a pathogenetic link with some diseases, in which a perturbation of intestinal microbiota may be involved. On these bases, we performed a review to explore the multiple links between SIBO and digestive and extra-intestinal diseases.

Systematic Review and Meta-Analysis: Accuracy of Both Gamma Delta+ Intraepithelial Lymphocytes and Coeliac Lymphogram Evaluated by Flow Cytometry for Coeliac Disease Diagnosis

It has been suggested that in doubtful cases of coeliac disease, a high CD3+ T-cell receptor gamma delta+ (TCRγδ+) intraepithelial lymphocyte count increases the likelihood of coeliac disease.

AIM

To evaluate the diagnostic accuracy of both an isolated increase of TCRγδ+ cells and a coeliac lymphogram (increase of TCRγδ+ plus decrease of CD3- intraepithelial lymphocytes) evaluated by flow cytometry in the diagnosis of coeliac disease.

METHODS

The literature search was conducted in MEDLINE and EMBASE. The inclusion criteria were: an article that allows for the construction of a 2 × 2 table of true and false positive and true and false negative values. A diagnostic accuracy test meta-analysis was performed.

RESULTS

The search provided 49 relevant citations, of which 6 were selected for the analysis, which represented 519 patients and 440 controls. Coeliac lymphogram: The pooled S and Sp were 93% and 98%, without heterogeneity. The area under the SROC curve (AUC) was 0.98 (95% CI, 0.97-0.99). TCRγδ+: Pooled S and Sp were both 95%, with significant heterogeneity. The AUC was 0.97 (95% CI, 0.95-0.98). Conclusions: Both TCRγδ+ count and coeliac lymphogram assessed by flow cytometry in duodenal mucosal samples are associated with a high level of diagnostic accuracy for and against coeliac disease.

Reduced interstitial cells of Cajal and increased intraepithelial lymphocytes are associated with development of small intestinal bacterial overgrowth in post-infectious IBS mouse model

OBJECTIVE

Intestinal dysmotility and immune activation are likely involved in the pathogenesis of small intestinal bacteria overgrowth (SIBO) in irritable bowel syndrome (IBS). We aimed at investigating the role of interstitial cells of Cajal (ICC) and intestinal inflammation in the development of SIBO using a post-infectious IBS (PI-IBS) mouse model.

MATERIALS AND METHODS

NIH mice were randomly infected with Trichinella spiralis. Visceral sensitivity and stool pattern were assessed at 8-weeks post-infection (PI). Intestinal bacteria counts from jejunum and ileum were measured by quantitative real-time PCR to evaluate the presence of SIBO. ICC density, intraepithelial lymphocytes (IELs) counts, and intestinal cytokine levels (IL1-β, IL-6, toll-like receptor-4 (TLR-4), IL-10) in the ileum were examined.

RESULTS

PI-IBS mice demonstrated increased visceral sensitivity compared with the control group. One-third of the PI-IBS mice developed SIBO (SIBO+/PI-IBS) and was more likely to have abnormal stool form compared with SIBO negative PI-IBS (SIBO-/PI-IBS) mice but without difference in visceral sensitivity. SIBO+/PI-IBS mice had decreased ICC density and increased IELs counts in the ileum compared with SIBO-/PI-IBS mice. No difference in inflammatory cytokine expression levels were detected among the groups except for increased TLR-4 in PI-IBS mice compared with the control group.

CONCLUSIONS

Development of SIBO in PI-IBS mice was associated with reduced ICC density and increased IELs counts in the ileum. Our findings support the role of intestinal dysmotility and inflammation in the pathogenesis of SIBO in IBS and may provide potential therapeutic targets.

Small intestinal bacterial overgrowth and celiac disease: A systematic review with pooled-data analysis

BACKGROUND

A link between small intestinal bacterial overgrowth (SIBO) and celiac disease (CD) has been hypothesized.

METHODS

Literature search was performed in main medical databases. Methods of analysis/inclusion criteria were based on Preferred Reporting Items for Systematic reviews and Meta-Analyses recommendations. The end-point was to estimate, by a pooled-data analysis, SIBO prevalence in CD. Proportions/percentages and their 95% confidence intervals (CI) were calculated by inverse variance method, whereas odd ratios (OR) and their 95% CI were estimated, where available, based on the Mantel-Haenszel method. Data were entered into the RevMan 5.3 software.

KEY RESULTS

Eleven articles fulfilled considered criteria. The pooled mean prevalence of SIBO in CD was 20% (95% CI of 10%-30%). In comparison to asymptomatic controls, CD was associated to higher risk of SIBO, with an OR of 10.52 (95% CI 2.69-41.21, P=.0007). Jejunal aspirate culture assessed SIBO prevalence of 11% (95% CI 3%-19%) in CD, whereas breath tests detected a higher value (23%, 95% CI 10%-37%). The pooled prevalence of SIBO in CD patients who were symptomatic despite a GFD was 28% (95% CI 10%-47%), higher than in asymptomatic celiac patients (pooled prevalence of 10%, with a 95% CI of 3%-16%), despite not statistically significant (P=.06). When GFD-unresponsive CD was defined only by clinical persistence of symptoms, the prevalence of SIBO was higher than in the case of villous atrophy association (31% vs 16% P=.33).

CONCLUSIONS

The heterogeneity of available studies may not support a relationship SIBO-CD. Nevertheless, SIBO could be more common in CD when symptoms do not improve after GFD.

Lymphocytic duodenitis or microscopic enteritis and gluten-related conditions: what needs to be explored?

Microscopic enteritis (ME) is characterized by abnormal infiltration of intraepithelial lymphocytes in intestinal mucosa. It was described as duodenal lymphocytosis or lymphocytic duodenitis until the dedicated Consensus Conference of 2015. ME represents a common feature of several gluten-mediated and non-gluten related diseases; therefore, it is an umbrella term embracing several conditions. The most frequent causes of ME are gluten-related disorders (celiac disease, non-celiac gluten sensitivity, wheat allergy), Helicobacter pylori infection and drug-related damages. Less frequently, ME may be secondary to inflammatory bowel disease, some autoimmune conditions, immunoglobulin deficiencies, blood malignancies, infections and irritable bowel syndrome. Therefore, the differential diagnosis of ME may be challenging. The diagnosis of ME needs to be driven by predominant symptoms and patient history. However, it is often difficult to achieve an immediate identification of the underlying condition, and a broad variety of diagnostic tests may be required. Ultimately, long-term surveillance is needed for a final diagnosis in many cases, since a hidden or quiescent condition may be disclosed after a period of latency. In any case, strict collaboration between the clinician and the pathologist is pivotal. The treatment of ME should be personalized, depending on the underlying disease. For gluten-related conditions (celiac disease, gluten sensitivity, wheat allergy, dermatitis herpetiformis), a gluten-free diet may be proposed. For other conditions, a targeted etiologic treatment is necessary. In conclusion, ME represents a novel entity that is attracting increasing interest. The growing epidemiologic trend confirms that it will become a common condition in clinical practice.

Adaptive diagnosis of coeliac disease

Coeliac disease has for a long time simply been regarded as a gluten-dependent enteropathy and a duodenal biopsy was required in all patients for the diagnosis. It is now accepted that autoimmunity against transglutaminase 2 is an earlier, more universal and more specific feature of coeliac disease than histologic lesions. Moreover, high serum levels of combined anti-transglutaminase 2 and anti-endomysium antibody positivity have excellent predictive value for the presence of enteropathy with villous atrophy. This makes the histology evaluation of the gut no longer necessary in well defined symptomatic paediatric patients with compatible HLA-DQ2 and/or DQ8 background. The biopsy-sparing diagnostic route is not yet recommended by gastroenterologists for adults, and certain clinical circumstances (immunodeficiency conditions, extraintestinal manifestations, type-1 diabetes mellitus, age less than 2 years) may require modified diagnostic approaches. Coeliac patients with preserved duodenal villous structure do exist and these need a more extended evaluation by immunologic and molecular biology tools.

Discriminant score for celiac disease based on immunohistochemical analysis of duodenal biopsies

OBJECTIVES

Celiac disease (CD) represents a spectrum, which includes cases with minor histological abnormalities (potential CD). The aim of this work is to evaluate the contribution of immunohistochemical analysis of duodenal biopsies to the diagnosis of gluten-related minor enteropathy.

METHODS

Duodenal biopsies from 56 patients with untreated CD and 56 controls were analyzed for CD3 and γδ intraepithelial lymphocyte number, γδ/CD3 ratio, and density of CD25+ lamina propria cells. A discriminant equation was obtained by which 61 more biopsies with normal villous architecture were blindly evaluated.

RESULTS

All of the immunohistochemical parameters were significantly different between patients with CD and controls. None of the single parameters showed sufficient specificity for CD. The combination of all of the 4 markers resulted in the following discriminant equation: discriminant score (Dscore) = (CD3 × 0.06) - (γδ × 0.119) + (CD25 × 0.012) + (γδ/CD3 × 0.131) - 4.709. Using this Dscore, patients were correctly classified as celiac or controls in 97.3% of the cases. When this equation was applied to a validation set of 61 patients with normal villous architecture and unknown diagnosis, 92.9% of those with a positive score turned out to be patients with potential CD. A normal score, however, did not exclude this condition.

CONCLUSIONS

Immunohistochemistry represents a specific tool for the diagnosis of CD, but does lack sensitivity in detecting all of the potential CD cases.

Clinical expression of lymphocytic duodenosis in "mild enteropathy" celiac disease and in functional gastrointestinal syndromes

OBJECTIVE

Abnormally high number of duodenal intraepithelial lymphocytes is frequently found in many conditions including mild enteropathy celiac disease (CD) and functional gastrointestinal syndromes, but is unclear whether lymphocytosis affects the clinical phenotype particularly in functional syndromes.

MATERIALS AND METHODS

We compared clinical characteristics of celiac patients with lymphocytic duodenosis and normal villous structure with those of patients with functional gastrointestinal syndromes with and without lymphocytic duodenosis. We retrospectively identified 3 cohorts among patients referred for suspected CD: (1) "CoelD", 135 patients (age 36 ± 14 years) with mild enteropathy CD; (2) "LymD", 245 patients (38 ± 12 years) with functional gastrointestinal syndromes and lymphocytic duodenosis; and (3) "NorD", 147 patients (37 ± 15 years) with functional syndromes and normal duodenal histology.

RESULTS

Prevalence of gastrointestinal symptoms was similar in the three cohorts, but prevalence of extra-intestinal manifestations (42% vs. 27% vs. 18%, p < 0.003) and of associated diseases (35% vs. 15% vs. 14%, p < 0.0001) was higher in "CoelD" than in "LymD" and "NorD", respectively. Prevalence of Helicobacter pylori infection was similar in the three cohorts. The proportion of patients with final diagnosis of irritable bowel syndrome-diarrhea (38% vs. 37%), dyspepsia (31% vs. 27%), functional pain (14% vs. 19%), and functional diarrhoea (14% vs. 11%) was virtually the same in the cohorts with (LymD) and without (NorD) lymphocytic duodenosis.

CONCLUSIONS

Lymphocytic duodenosis has different clinical presentation in patients with mild enteropathy CD than those with functional gastrointestinal syndromes, and is not specific for any particular functional syndrome.

Irritable bowel syndrome: methods, mechanisms, and pathophysiology. Neural and neuro-immune mechanisms of visceral hypersensitivity in irritable bowel syndrome

Irritable bowel syndrome (IBS) is characterized as functional because a pathobiological cause is not readily apparent. Considerable evidence, however, documents that sensitizing proinflammatory and lipotoxic lipids, mast cells and their products, tryptases, enteroendocrine cells, and mononuclear phagocytes and their receptors are increased in tissues of IBS patients with colorectal hypersensitivity. It is also clear from recordings in animals of the colorectal afferent innervation that afferents exhibit long-term changes in models of persistent colorectal hypersensitivity. Such changes in afferent excitability and responses to mechanical stimuli are consistent with relief of discomfort and pain in IBS patients, including relief of referred abdominal hypersensitivity, upon intra-rectal instillation of local anesthetic. In the aggregate, these experimental outcomes establish the importance of afferent drive in IBS, consistent with a larger literature with respect to other chronic conditions in which pain is a principal complaint (e.g., neuropathic pain, painful bladder syndrome, fibromyalgia). Accordingly, colorectal afferents and the environment in which these receptive endings reside constitute the focus of this review. That environment includes understudied and incompletely understood contributions from immune-competent cells resident in and recruited into the colorectum. We close this review by highlighting deficiencies in existing knowledge and identifying several areas for further investigation, resolution of which we anticipate would significantly advance our understanding of neural and neuro-immune contributions to IBS pain and hypersensitivity.

A prospective study into the aetiology of lymphocytic duodenosis

BACKGROUND

Lymphocytic duodenosis is defined by normal villous architecture and intraepithelial lymphocytes (IELs) >25 per 100 enterocytes. Such patients should not be diagnosed with coeliac disease, solely by histology, as previous retrospective studies have suggested other associations with lymphocytic duodenosis.

AIM

To study prospectively the aetiology of lymphocytic duodenosis.

METHODS

One hundred patients with lymphocytic duodenosis were investigated rigorously for coeliac disease and other known associations for lymphocytic duodenosis by initial investigations of coeliac serology, and exclusion of infection. Of 34 with no explanation for lymphocytic duodenosis, 29 underwent repeat duodenal biopsies following a gluten challenge.

RESULTS

Coeliac disease was present in 16% of patients with lymphocytic duodenosis. In the absence of a positive coeliac diagnosis, lymphocytic duodenosis was most commonly associated with drugs (21%), infection (19%), immune dysregulation (4%), inflammatory bowel disease (2%), microscopic colitis (2%), sarcoidosis (1%) and IgA deficiency (1%). Of 34 with no known associations, 18 had symptoms of irritable bowel syndrome (IBS), and in 29 patients investigated with repeat duodenal biopsies, the IEL count returned to normal in 22.

CONCLUSIONS

In 66% of cases of lymphocytic duodenosis, a known association can be found by further investigations; importantly, 16% will have coeliac disease. In those with no apparent cause, there may be an association with IBS and the IEL count becomes normal on repeat biopsy in 76%.

Usefulness of small-bowel mucosal transglutaminase-2 specific autoantibody deposits in the diagnosis and follow-up of celiac disease

BACKGROUND

Diagnosis of celiac disease may be problematic in that small-bowel villous atrophy sometimes occurs in conjunction with other enteropathies, develops gradually and may be patchy. Furthermore, as the often compromised quality of biopsy specimens renders diagnosis difficult, new diagnostic tools are warranted.

GOALS

As the celiac disease-specific autoantibodies are found deposited at their production site, in the small-bowel mucosa, they may be useful in diagnostics, especially in problematic cases. We therefore systematically assessed the occurrence of celiac-specific autoantibody deposits in a large cohort of celiac patients, and established how IgA deposits decline after initiation of a gluten-free diet.

METHODS

Transglutaminase-2 specific mucosal IgA autoantibody deposits were determined from small-bowel mucosal biopsies in 261 untreated, 71 short-term (1 y), and 105 long-term (2 to 41 y) treated celiac disease patients and in 78 nonceliac controls. The presence of the deposits was compared with celiac serology, mucosal villous morphology and density of intraepithelial lymphocytes.

RESULTS

All untreated celiac disease patients had mucosal autoantibody deposits and their intensity was moderate or strong in 90% of cases. In contrast, 18% of the controls had weak depositions. During a gluten-free diet the intensity of the deposits diminished, but was still faintly positive in 56% of long-term treated celiac patients. The efficiency of the test in determining mucosal autoantibody deposits was superior to serology and inflammatory markers.

CONCLUSIONS

Mucosal transglutaminase-2 specific autoantibody deposits proved to be accurate gluten-dependent markers of celiac disease and would thus be of value in the diagnostics and dietary monitoring of this disorder.

Prevalence of celiac disease among first degree relatives of Brazilian celiac patients

BACKGROUND

Several studies have shown that celiac disease, an autoimmune disorder that occurs in genetically susceptible individuals, is highly prevalent among relatives of celiac patients.

AIM

To determine the prevalence of celiac disease in a group of first degree relatives of Brazilian celiac patients.

METHODS

First degree relatives of celiac patients attending the Brasilia University Hospital Pediatric Gastroenterology Outpatient Clinic or the Celiac Disease Investigation Center, Brasília, DF, Brazil, between March 2001 and November 2004 were invited to undergo serological screening for celiac disease applying the IgA anti-endomysium antibody test (IgA-EMA). All positive IgA-EMA sera underwent a second screening using the IgA anti-tissue transglutaminase antibodies test. Duodenal or small intestinal biopsies were performed in all subjects positive to serological testing. Biopsy samples were classified as type (O) normal, (I) infiltrative, (II) infiltrative hyperplastic, (III) flat destructive, and (IV) atrophic hypoplastic. The final diagnosis was ascertained in subjects showing positive serological tests and a grade I to III small intestinal lesion.

RESULTS

Nine new cases of celiac disease were found among the 188 first degree relatives tested (4.8%).

CONCLUSION

The present study confirms the high prevalence of celiac disease among first degree celiac patients relatives and reinforces the need of extensive diagnostic screening in this specific group.