Deficiency of 6B11+ invariant NK T-cells in celiac disease

Intraepithelial lymphocytes subsets in different forms of celiac disease

AIM

The enumeration of intraepithelial lymphocytes subsets (total, γδ, and CD3(-) IELs) by flow cytometry (FCM), named as IEL lymphogram, constitutes a useful tool for celiac disease (CD) diagnosis. The aim of this study was to quantify IELs by FCM and their diagnostic value to differentiate active, silent and potential CD.

METHODS

Prospective study of 60 active and 20 silent CD patients, and 161 controls in which duodenal biopsy and IEL quantification by FCM was performed.

RESULTS

Active and silent CD patients had significant higher levels of both total and γδ IELs than absent CD patients (P < 0.0001 and P < 0.0001, P = 0.012 and P < 0.011; respectively). Active and silent CD patients had significant lower levels of CD3(-) IELs than absent CD patients (P < 0.047 and P < 0.009, respectively). Moreover, they were lower in silent than in active CD patients (P = 0.002). Changes of IELs subsets were more marked in children than adults active CD. The optimal IEL lymphogram cut off values for active CD diagnosis were: ≥10, ≥15 and ≤9 %, and with better performance characteristics for silent CD: ≥ 11, ≥10 and ≤5 %.

CONCLUSION

The evaluation of IELs subsets by FCM is useful to confirm diagnosis of active and silent CD.

TCDD modulation of gut microbiome correlated with liver and immune toxicity in streptozotocin (STZ)-induced hyperglycemic mice

An increasing body of evidence has shown the important role of the gut microbiome in mediating toxicity following environmental contaminant exposure. The goal of this study was to determine if the adverse metabolic effects of chronic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure would be sufficient to exacerbate hyperglycemia, and to further determine if these outcomes were attributable to the gut microbiota alteration. Adult male CD-1 mice were exposed to TCDD (6μg/kg body weight biweekly) by gavage and injected (i.p.) with STZ (4×50mg/kg body weight) to induced hyperglycemia. 16S rRNA sequencing was used to characterize the changes in the microbiome community composition. Glucose monitoring, flow cytometry, histopathology, and organ characterization were performed to determine the deleterious phenotypic changes of TCDD exposure. Chronic TCDD treatment did not appear to exacerbate STZ-induced hyperglycemia as blood glucose levels were slightly reduced in the TCDD treated mice; however, polydipsia and polyphagia were observed. Importantly, TCDD exposure caused a dramatic change in microbiota structure, as characterized at the phylum level by increasing Firmicutes and decreasing Bacteroidetes while at the family level most notably by increasing Lactobacillaceae and Desulfovibrionaceae, and decreasing Prevotellaceae and ACK M1. The changes in microbiota were further found to be broadly associated with phenotypic changes seen from chronic TCDD treatment. In particular, the phylum level Bacteroidetes to Firmicutes ratio negatively correlated with both liver weight and liver pathology, and positively associated with %CD3(+)NK(+) T cells, a key mediator of host-microbial interactions. Collectively, these findings suggest that the dysregulated gut microbiome may contribute to the deleterious effects (e.g., liver toxicity) seen with TCDD exposure.

Increased Intraepithelial Vα24 Invariant NKT Cells in the Celiac Duodenum

Celiac Disease (CD) is an interferon (IFN)γ-mediated duodenal hypersensitivity to wheat gluten occurring in genetically predisposed individuals. Gluten-free diet (GFD) leads to a complete remission of the disease. Vα24-restricted invariant NKT (iNKT) cells are important to maintain immune homeostasis in the gut mucosa because of their unique capacity to rapidly produce large quantities of both T-helper (Th)1 and Th2 cytokines upon stimulation. We studied the presence of these cells in the CD duodenum. Duodenal biopsies were obtained from 45 untreated-CD patients (uCD), 15 Gluten Free Diet-CD patients (GFD-CD), 44 non-inflamed non-CD controls (C-controls) and 15 inflamed non-CD controls (I-controls). Two populations from Spain and Argentina were recruited. Messenger RNA (mRNA) expression of Vα24-Jα18 (invariant TCRα chain of human iNKT cells), IFNγ and intracellular transcription factor Forkhead Box P3 (Foxp3), and flow cytometry intraepithelial lymphocyte (IEL) profile were determined. Both uCD and GFD-CD patients had higher Vα24-Jα18 mRNA levels than non-CD controls (I and C-controls). The expression of Vα24-Jα18 correlated with Marsh score for the severity of mucosal lesion and also with increased mRNA IFNγ levels. uCD and GFD-CD patients had decreased mRNA expression of FoxP3 but increased expression of Vα24-Jα18, which revealed a CD-like molecular profile. Increased numbers of iNKT cells were confirmed by flow cytometry within the intraepithelial lymphocyte compartment of uCD and GFD-CD patients and correlated with Vα24-Jα18 mRNA expression. In conclusion, we have found an increased number of iNKT cells in the duodenum from both uCD and GFD-CD patients, irrespective of the mucosal status. A CD-like molecular profile, defined by an increased mRNA expression of Vα24-Jα18 together with a decreased expression of FoxP3, may represent a pro-inflammatory signature of the CD duodenum.

Activation of invariant NK T cells in periodontitis lesions

Periodontitis is one of the most prevalent human inflammatory diseases. The major clinical phenotypes of this polymicrobial, biofilm-mediated disease are chronic and aggressive periodontitis, the latter being characterized by a rapid course of destruction that is generally attributed to an altered immune-inflammatory response against periodontal pathogens. Still, the biological basis for the pathophysiological distinction of the two disease categories has not been well documented yet. Type I NKT cells are a lymphocyte subset with important roles in regulating immune responses to either tolerance or immunity, including immune responses against bacterial pathogens. In this study, we delineate the mechanisms of NKT cell activation in periodontal infections. We show an infiltration of type I NKT cells in aggressive, but not chronic, periodontitis lesions in vivo. Murine dendritic cells infected with aggressive periodontitis-associated Aggregatibacter actinomycetemcomitans triggered a type I IFN response followed by type I NKT cell activation. In contrast, infection with Porphyromonas gingivalis, a principal pathogen in chronic periodontitis, did not induce NKT cell activation. This difference could be explained by the absence of a type I IFN response to P. gingivalis infection. We found these IFNs to be critical for NKT cell activation. Our study provides a conceivable biological distinction between the two periodontitis subforms and identifies factors required for the activation of the immune system in response to periodontal bacteria.

From genome-wide association studies to disease mechanisms: celiac disease as a model for autoimmune diseases

Celiac disease is characterized by a chronic inflammatory reaction in the intestine and is triggered by gluten, a constituent derived from grains which is present in the common daily diet in the Western world. Despite decades of research, the mechanisms behind celiac disease etiology are still not fully understood, although it is clear that both genetic and environmental factors are involved. To improve the understanding of the disease, the genetic component has been extensively studied by genome-wide association studies. These have uncovered a wealth of information that still needs further investigation to clarify its importance. In this review, we summarize and discuss the results of the genetic studies in celiac disease, focusing on the "non-HLA" genes. We also present novel approaches to identifying the causal variants in complex susceptibility loci and disease mechanisms.

From genome-wide association studies to disease mechanisms: celiac disease as a model for autoimmune diseases

Celiac disease is characterized by a chronic inflammatory reaction in the intestine and is triggered by gluten, a constituent derived from grains which is present in the common daily diet in the Western world. Despite decades of research, the mechanisms behind celiac disease etiology are still not fully understood, although it is clear that both genetic and environmental factors are involved. To improve the understanding of the disease, the genetic component has been extensively studied by genome-wide association studies. These have uncovered a wealth of information that still needs further investigation to clarify its importance. In this review, we summarize and discuss the results of the genetic studies in celiac disease, focusing on the “non-HLA” genes. We also present novel approaches to identifying the causal variants in complex susceptibility loci and disease mechanisms.

Dynamics of non-conventional intraepithelial lymphocytes-NK, NKT, and γδ T-in celiac disease: relationship with age, diet, and histopathology

BACKGROUND

Intraepithelial lymphocytes (IEL) are a heterogeneous population of lymphocytes raised in celiac disease (CD), whose role in CD pathogenesis remains to be defined.

AIMS

To investigate how the age of diagnosis, diet, and the severity of the histological lesions are related to the changes observed in unconventional IEL populations.

METHODS

Prospective analysis of 101 confirmed celiac patients from a single center, including 66 at diagnosis (45 children, 21 adults) and 112 non-celiac controls (12 children, 100 adults). IEL from duodenal biopsies were studied by six-color flow cytometry. The results were analyzed in relationship with age, diet (gluten intake), and histopathology (Marsh type).

RESULTS

In comparison with respective age controls, both children and adult patients showed duodenal intraepithelial lymphocytosis with significant differences in every single non-conventional IEL population: CD3+ TCR γδ, NK (CD3-, CD16+, CD56+), NKT (CD3+, CD161+, CD56+), and iNKT (CD3+ Vα24) (P < 0.001 for all). Gluten intake was not only directly associated with severe atrophy, but also with decreased percentages of NK (P = 0.02), NKT (P = 0.003), and iNKT (P = 0.03). Changes in iNKT and γδ IEL were more marked in celiac children compared with celiac adults (P = 0.02 and 0.01, respectively). In contrast, increased CD3+ TCR γδ were diet- and Marsh grade-independent.

CONCLUSIONS

The typical phenotypical profile of intraepithelial lymphocytosis in untreated pediatric and adult celiacs consists of increased CD3+ TCR γδ populations with decreased NK, NKT, and iNKT cells. NK, NKT, and iNKT IEL, but not γδ IEL, are dynamic populations associated with diet, age, and histopathology.

Immune phenotype of children with newly diagnosed and gluten-free diet-treated celiac disease

BACKGROUND

Recent data suggest the involvement of both the adaptive and the innate immune system in celiac disease (CD). However, little is known about the immune phenotype of children with CD and its alteration upon dietary intervention.

AIMS

We characterized the prevalence of major interacting members of the adaptive and innate immune system in peripheral blood of newly diagnosed children with CD and tested its alteration with the improvement of clinical signs after the introduction of gluten-free diet (GFD).

METHODS

Peripheral blood was taken from ten children with biopsy-proven CD at the time of diagnosis and after the resolution of clinical symptoms following GFD. As controls, 15 children with functional abdominal pain were enrolled. The prevalence of the cells of adaptive and innate immunity was measured with labeled antibodies against surface markers and intracellular FoxP3 using a flow cytometer.

RESULTS

Patients with CD were found to have lower T helper, Th1 and natural killer (NK), NKT and invariant NKT cell prevalence and with higher prevalence of activated CD4(+) cells, myeloid dendritic cells (DC) and Toll-like receptor (TLR) 2 and TLR-4 positive DCs and monocytes compared to controls. After resolution of symptoms on GFD, the majority of these changes normalized, although the prevalence of NK and NKT cell, DC and TLR-2 expressing DCs and monocytes remained abnormal.

CONCLUSIONS

The immune phenotype in childhood CD indicates the implication of both adaptive and innate immune system. The normalization of immune abnormalities occurs on GFD, but the kinetics of this process probably differs among different cell types.

Celiac disease

PURPOSE OF REVIEW

To summarize recent advances in celiac disease published between August 2008 and July 2009.

RECENT FINDINGS

Celiac disease affects nearly 1% of most populations but remains largely unrecognized. In the last year, work has shown that the prevalence of celiac disease has increased dramatically, not simply due to increased detection. Also, undiagnosed celiac disease may be associated with increased mortality. Significant progress has been made in understanding how gliadin peptides can cross the intestinal border and access the immune system. New genetic loci and candidate genes that may contribute to the risk of celiac disease and its overlap with type 1 diabetes mellitus have been identified. Novel deamidated gliadin peptides antibodies have better diagnostic accuracy over native gliadin-based tests. The inclusion of duodenal bulb biopsy specimens may increase the rate of celiac disease detection. The spectrum of celiac disease likely includes a minority of patients with mild enteropathy. A practical seven-item instrument may facilitate standardized evaluation of gluten-free diet adherence. Finally, refractory celiac disease, although rare, is associated with a poor prognosis.

SUMMARY

Celiac disease is a global health problem that requires a multidisciplinary and increasingly cooperative multinational research effort.

Recent advances in coeliac disease

PURPOSE OF REVIEW

Worldwide awareness of coeliac disease in all ages continues to grow. This article aims to summarize critically the recent research advances in coeliac disease.

RECENT FINDINGS

Large multicentre studies have provided further evidence of the role of environmental and nonhuman leucocyte antigen genetic factors in coeliac disease. Siblings of coeliac patients carry a high risk, but those found to have negative coeliac serology are very unlikely to develop the disease. Advances in the efficacy of serological antibody testing potentiate the possibility of future accurate screening programmes in the community. Adherence to a gluten-free diet remains paramount as the recognition of coeliac related complications increases.

SUMMARY

Despite the encouraging progress that has taken place in our genetic and immunological knowledge of coeliac disease, early introduction of a gluten-free diet remains the cornerstone of treatment. Alternatives, however, aimed at altering the toxicity of cereal proteins are now looking more promising.