Increased levels of circulating ICAM-1, E-selectin, and IL-2 receptors in celiac disease

Molecular and Structural Parallels between Gluten Pathogenic Peptides and Bacterial-Derived Proteins by Bioinformatics Analysis

Gluten-related disorders (GRDs) are a group of diseases that involve the activation of the immune system triggered by the ingestion of gluten, with a worldwide prevalence of 5%. Among them, Celiac disease (CeD) is a T-cell-mediated autoimmune disease causing a plethora of symptoms from diarrhea and malabsorption to lymphoma. Even though GRDs have been intensively studied, the environmental triggers promoting the diverse reactions to gluten proteins in susceptible individuals remain elusive. It has been proposed that pathogens could act as disease-causing environmental triggers of CeD by molecular mimicry mechanisms. Additionally, it could also be possible that unrecognized molecular, structural, and physical parallels between gluten and pathogens have a relevant role. Herein, we report sequence, structural and physical similarities of the two most relevant gluten peptides, the 33-mer and p31-43 gliadin peptides, with bacterial pathogens using bioinformatics going beyond the molecular mimicry hypothesis. First, a stringent BLASTp search using the two gliadin peptides identified high sequence similarity regions within pathogen-derived proteins, e.g., extracellular proteins from Streptococcus pneumoniae and Granulicatella sp. Second, molecular dynamics calculations of an updated α-2-gliadin model revealed close spatial localization and solvent-exposure of the 33-mer and p31-43 peptide, which was compared with the pathogen-related proteins by homology models and localization predictors. We found putative functions of the identified pathogen-derived sequence by identifying T-cell epitopes and SH3/WW-binding domains. Finally, shape and size parallels between the pathogens and the superstructures of gliadin peptides gave rise to novel hypotheses about activation of innate immunity and dysbiosis. Based on our structural findings and the similarities with the bacterial pathogens, evidence emerges that these pathologically relevant gluten-derived peptides could behave as non-replicating pathogens opening new research questions in the interface of innate immunity, microbiome, and food research.

Celiac Disease in Children, Particularly with Accompanying Type 1 Diabetes, Is Characterized by Substantial Changes in the Blood Cytokine Balance, Which May Reflect Inflammatory Processes in the Small Intestinal Mucosa

Cytokines play a pivotal role in the maintenance of intestinal homeostasis inducing pro- or anti-inflammatory response and mucosal barrier function in celiac disease (CD) and type 1 diabetes (T1D). We aimed to compare the levels of pro- and anti-inflammatory cytokines in CD patients without and with coexisting T1D, as well as to evaluate its association with the presence of enteroviruses (EV), regulatory T cells (Tregs), and dendritic cells (DCs) in small bowel mucosa. Altogether, 72 patients (median age 10.1 years) who had undergone small bowel biopsy were studied. The study group consisted of 24 patients with CD (median age 6.5 years), 9 patients with CD and concomitant T1D (median age 7.0 years), two patients with T1D (median age 8.5 years), and 37 patients (median age 14.0 years) with functional gastrointestinal disorders (FGD) and a normal small bowel mucosa as controls. The levels of 33 cytokines in serum were measured by multiple analysis using the Milliplex® MAP Magnetic Bead assay. The densities of FOXP3+ Tregs, CD11c+ DC, indoleamine 2,3-dioxygenase+ (IDO+) DC, langerin+ (CD207+) DCs, and EV were evaluated by immunohistochemistry as described in our previous studies. Circulating anti-EV IgA and IgG were evaluated using ELISA. The most important finding of the study is the significant increase of the serum levels of IL-5, IL-8, IL-13, IL-15, IL-17F, IL-22, IL-27, IP-10, MIP-1β, sIL-2Rα, sTNFRII, and TNFα in CD patients compared to controls and its correlation with the degree of small bowel mucosa damage graded according to the Marsh classification. The leptin level was higher in females in all study groups. The levels of IL-2, IL-6, IL-12 (P70), IL-15, IP-10, and IFNγ correlated significantly with the density of FOXP3+ Tregs in lamina propria of the small bowel mucosa, which supports the evidence about the signaling role of these cytokines in the peripheral maintenance of FOXP3+ Tregs. At the same time, a significant negative correlation occurred between the level of IL-4 and density of FOXP3+ Tregs in controls. Another important finding of our study was the correlation of IL-17F, IP-10, sTNFRII, MCP-1, and GM-CSF with the density of EV-positive cells in the lamina propria of the small bowel mucosa. Correlation of MIP-1 (CCL-4) with CD103+ DC and langerin+ DC densities may point to their significance in the recruitment of immune cells into the lamina propria and in driving the inflammatory response in CD patients. Our results suggest the predominance of Th1 and Th17 immune responses over EV VP1 protein in CD and T1D patients. The significant elevation of Th2 cytokines, like IL-5 and IL-13, but not IL-4, in CD patients and its correlation with the degree of small bowel mucosa damage could reflect the role of these cytokines in gut defense and inflammation.

Assessment of Endothelial Dysfunction With Adhesion Molecules in Patients With Celiac Disease

OBJECTIVES

Celiac disease (CD) is a systemic immune disorder. We assessed serum levels of adhesion molecules as a marker of endothelial dysfunction in patients with CD at first diagnosis and in those on a gluten-free diet.

METHODS

Sixty-five patients with CD (mean age 6.74 ± 4.6 years) and 51 age- and sex-matched control patients participated in the present case-controlled, prospective clinical study. Serum levels of vascular adhesion molecule-1, intercellular adhesion molecule-1, endothelial selectin, vascular endothelial cadherin, high-sensitivity C-reactive protein, and homocysteine levels were measured.

RESULTS

Average soluble vascular adhesion molecule-1 (CD vs control group: 1320 ± 308 vs 1120 ± 406 ng/mL, P = 0.006), soluble intercellular adhesion molecule-1 (336 ± 99 vs 263 ± 67 ng/mL, P = 0.025), and soluble endothelial selectin (113.9 ± 70 vs 76.9 ± 32 ng/mL, P = 0.007) levels were significantly higher in cases of newly diagnosed CD than in the control group. Soluble vascular adhesion molecule-1 (1050 ± 190 ng/mL) and soluble endothelial selectin (68.7 ± 45 ng/mL) levels in patients with CD, who were fully compliant with a gluten-free diet, were significantly lower than that in those newly diagnosed as having CD (P = 0.003 and P = 0.0012, respectively).

CONCLUSIONS

These results show that serum adhesion molecule levels are higher in patients with CD. Some of the risks associated with endothelial dysfunction may be related to CD and these risks can be reduced with an appropriate and fully controlled diet.

Serum soluble interleukin-2 receptor, interleukin-6 and tumor necrosis factor alpha as markers of celiac disease activity

OBJECTIVES

To evaluate the markers of lymphocyte activation (sIL-2R, IL-6 and TNF α) in the peripheral blood of newly diagnosed patients with celiac disease (CD) and patients with CD on Gluten free diet (GFD) for at least 2 y. The markers were correlated with conventional serological tests Anti-tissue transglutaminase (Anti-TTG) used for diagnosis and follow up of the disease; wherever possible.

METHODS

Thirty newly diagnosed cases of CD (on the basis of histopathology and serology) not on GFD were enrolled as Group 1 of the study. Thirty age and sex matched controls from the Pediatric Surgery OPD formed Group 2. Thirty cases of CD on GFD for at least 2 y (Group 3) were also enrolled in the study. Upper G.I. endoscopy was performed in all Group 1 patients and cytokine levels assayed by ELISA on serum obtained from all patients in Groups 1, 2, 3.

RESULTS

Mean sIL-2R level in Group 1(1498.1+/-1234.31 pg/ml) and Group 3 (488.78+/-396.18 pg/ml) were significantly higher than the controls (336.27+/-218.67 pg/ml p < 0.05). Among the patients with CD, mean serum levels in Group 1 were higher than in Group 3 (p < 0.05). sIL-2R levels showed good correlation with tTg levels in Group 1 patients (p < 0.000, r = 0.69). Mean IL-6 levels in Group 1 were significantly higher (28.43+/-28.32 pg/ml) than Group 2(15.03+/-7.72 pg/ml p < 0.05) and Group 3(11.26+/-5.13 pg/ml p < 0.05). IL-6 levels were comparable between Groups 2 and 3 (p > 0.05).IL-6 levels showed good correlation with tTg levels in Group 1(p < 0.008, r = 0.471). Mean TNFα levels in Group 1(179.66+/-102.93 pg/ml), Group 2 (153.16+/-27.02 pg/ml) and Group 3 (166.67+/-28.95 pg/ml) were comparable (p > 0.05). TNFα levels showed poor correlation with tTg levels in Group 1 patients (p > 0.604, r = -0.099).

CONCLUSIONS

sIL-2R and IL-6 levels have a good correlation with CD activity and can be used as reliable markers for detecting minimal transgression from GFD.

Celiac disease IgA modulates vascular permeability in vitro through the activity of transglutaminase 2 and RhoA

Celiac disease is characterized by the presence of specific autoantibodies targeted against transglutaminase 2 (TG2) in untreated patients' serum and at their production site in the small-bowel mucosa below the basement membrane and around the blood vessels. As these autoantibodies have biological activity in vitro, such as inhibition of angiogenesis, we studied if they might also modulate the endothelial barrier function. Our results show that celiac disease patient autoantibodies increase endothelial permeability for macromolecules, and enhance the binding of lymphocytes to the endothelium and their transendothelial migration when compared to control antibodies in an endothelial cell-based in vitro model. We also demonstrate that these effects are mediated by increased activities of TG2 and RhoA. Since the small bowel mucosal endothelium serves as a "gatekeeper" in inflammatory processes, the disease-specific autoantibodies targeted against TG2 could thus contribute to the pathogenic cascade of celiac disease by increasing blood vessel permeability.

Gliadin peptides activate blood monocytes from patients with celiac disease

To elucidate the role of innate immune responses in celiac disease, we investigated the effect of gliadin on blood monocytes from patients with celiac disease. Gliadin induced substantial TNF-alpha and IL-8 production by monocytes from patients with active celiac disease, lower levels by monocytes from patients with inactive celiac disease, and even lower levels by monocytes from healthy donors. In healthy donor monocytes gliadin induced IL-8 from monocytes expressing HLA-DQ2 and increased monocyte expression of the costimulatory molecules CD80 and CD86, the dendritic cell marker CD83, and the activation marker CD40. Gliadin also increased DNA binding activity of NF-kappaB p50 and p65 subunits in monocytes from celiac patients, and NF-kappaB inhibitors reduced both DNA binding activity and cytokine production. Thus, gliadin activation of HLA-DQ2(+) monocytes leading to chemokine and proinflammatory cytokine production may contribute to the host innate immune response in celiac disease.

Polymorphism in L-Selectin, E-Selectin and ICAM-1 Genes in Asian Indian Pediatric Patients With Celiac Disease

Celiac disease (CD) follows an autoimmune course in which both genetic and environmental factors contribute to its development. A strong association with HLA class II molecules, predominantly HLA-DQ2, has been reported in most ethnic groups with CD. The aim of this study was to determine if genetic polymorphisms in L-selectin, E-selectin, and intercellular adhesion molecule-1 (ICAM-1) have any correlation with CD. We investigated 5 mutations, namely F206L in L-selectin, S128R and L554F in E-selectin, and G241R and K469E in ICAM-1, in 37 North Indian pediatric patients with CD. A significant increase in allele frequencies of 128R of E-selectin and the associated genotype SR was observed in patients. No significant differences were observed in the F206L polymorphism of L-selectin, or the G241R and E469K polymorphisms in the ICAM-1 gene in CD. This study illustrates that selectin gene polymorphism might contribute to the genetic background of CD and invites further investigation relevant to understanding the mechanisms underlying the immunopathogenesis of this autoimmune disease.

Adulthood-Onset Celiac Disease Is Associated with Intercellular Adhesion Molecule-1 (ICAM-1) Gene Polymorphism

Celiac disease (CD) is a multifactorial T-cell-mediated autoimmune disease characterized by gluten-triggered villous atrophy and malabsorption. Although human leukocyte antigen (HLA) class II genes are strong susceptibility factors, non-HLA genes likely contribute to most of CD predisposition. The intercellular adhesion molecule-1 (ICAM-1) gene is a good candidate for CD predisposition because its encoded protein acts as an adhesion and costimulatory receptor. Two single-base polymorphisms (G/A in exon 4 encoding G241R, and A/G in exon 6 encoding K469E) were analyzed in 180 French Caucasian CD case patients (110 patients diagnosed before the age of 15 and 70 patients after the age of 18), and 212 French Caucasian healthy controls. The R241 allele frequency was increased in CD case patients compared with controls (14.2% vs. 5.4% respectively, p = 0.000015, odds ratio [OR] for the R241 allele = 2.9, 95% confidence intervals [CI] = 1.7-4.8). After stratifying for age of disease onset, the R241 variant mainly conferred predisposition to CD occurring during adulthood (OR = 4.2, 95% CI = 2.3-7.5, Pc = 0.000004 for adulthood-onset CD vs. R = 2.1, 95%, CI = 1.2-3.9, Pc = 0.0047 for childhood-onset CD). Position 241 of ICAM-1 maps to the binding site for the integrin Mac-1 and might modify the strength of interaction between endothelium and immune cells. If confirmed in independent datasets, these results may be of importance in at-risk individuals to distinguish rapid from delayed progression to clinical CD.

Cutaneous Endothelial Cell Activation in Normal Skin of Patients with Dermatitis Herpetiformis Associated with Increased Serum Levels of IL-8, sE-Selectin, and TNF-α

The mechanisms that lead to the development of skin lesions in patients with dermatitis herpetiformis (DH) are not known. We hypothesized that an ongoing immune response in the gut of patients with DH would result in an increase in circulating cytokines and be associated with endothelial cell activation, creating a proinflammatory environment in the skin. Skin biopsies from the normal-appearing inner arm of 11 DH patients, with no active skin lesions, and 12 normal subjects were analyzed for E-selectin (E-sel) and ICAM-1 mRNA. DH patients' skin expressed markedly increased levels of E-sel mRNA. Mean E-sel mRNA expression in DH skin was 1,271 (range 63.78-5861) times greater than that of a control, normal skin (P<0.001) with no significant increased expression of ICAM-1 mRNA. Serum levels of soluble E-selectin (sE-sel), IgA anti-tissue transglutaminase antibodies, and serum IL-8 levels were significantly increased in patients with DH. These studies demonstrate that patients with DH have evidence of endothelial cell activation in the skin and systemic manifestations of the ongoing inflammation associated with the mucosal immune response. Endothelial cell activation may play a critical role in the development of skin lesions in patients with DH and may represent a common mechanism for cutaneous manifestations of inflammatory gastrointestinal diseases.

The gluten connection: the association between schizophrenia and celiac disease

OBJECTIVE

Schizophrenia affects roughly 1% of the population and is considered one of the top 10 causes of disability worldwide. Given the immense cost to society, successful treatment options are imperative. Based on initial findings, gluten withdrawal may serve as a safe and economical alternative for the reduction of symptoms in a subset of patients.

METHOD

A review of the literature relevant to the association between schizophrenia and celiac disease (gluten intolerance) was conducted.

RESULTS

A drastic reduction, if not full remission, of schizophrenic symptoms after initiation of gluten withdrawal has been noted in a variety of studies. However, this occurs only in a subset of schizophrenic patients.

CONCLUSION

Large-scale epidemiological studies and clinical trials are needed to confirm the association between gluten and schizophrenia, and address the underlying mechanisms by which this association occurs.

Neutrophil CD11b, L-selectin and Fc IgA receptors in patients with dermatitis herpetiformis

BACKGROUND

The skin lesions found in patients with dermatitis herpetiformis (DH) are characterized by the presence of neutrophils at the dermal papillary tips in areas where the diagnostic cutaneous IgA deposits are found. Although the presence of the skin lesions of DH is known to be associated with gluten-sensitive enteropathy, the mechanisms that control the development of skin lesions are not known.

OBJECTIVES

To determine if circulating neutrophils from patients with DH have evidence of priming as shown by increased expression of CD11b, decreased expression of L-selectin and increased function of neutrophil Fc IgA receptor.

METHODS

Neutrophils from 12 normal subjects and 10 DH patients with active, ongoing disease and 14 DH patients with quiescent disease activity were examined by fluorescence-activated cell sorter for expression of cell surface CD11b, L-selectin expression, Fc IgA expression (CD89) and for the function of the Fc IgA receptor by determining the binding capacity of neutrophils for monoclonal human IgA.

RESULTS

Neutrophils from patients with active, ongoing DH had increased expression of CD11b when compared with patients with inactive DH or normal subjects [mean net geometric mean channel fluorescence (GMCF): active DH, 403.3; inactive DH, 237.8; normal subjects, 290.5; P < 0.05]. L-selectin expression in both groups of DH patients was significantly lower than that seen in normal subjects (mean net GMCF: active DH, 363.2; inactive DH, 375.2; normal subjects, 432.7; P < 0.05). No difference in CD89 expression was seen in any of the groups; however, the function of Fc IgA receptor was increased in patients with active DH when compared with patients with inactive DH and normal subjects.

CONCLUSIONS

Neutrophils from patients with active, ongoing DH show an increased expression of CD11b, decreased expression of L-selectin and increased ability to bind IgA, consistent with a pattern of priming of the neutrophils. This priming may occur in the gut as a result of the ongoing mucosal immune response that is present in patients with DH on a gluten-containing diet and may predispose neutrophils to localize in the skin of patients with DH.

Celiac disease

Celiac disease is more prevalent than it was previously thought to be, and screening of selected population groups may reveal many new cases. Tissue transglutaminase appears to have a significant role in the degradation of gliadin and antigen production. Specific gliadin epitopes have been defined using T-cell responses. Bone disease is a significant problem for patients with celiac disease but management guidelines are being developed. Refractory sprue (nonresponsive celiac disease) appears to be a manifestation of enteropathy-associated T-cell lymphoma in most cases.