A Functional Idiotype/Anti-Idiotype Network Is Active in Genetically Gluten-Intolerant Individuals Negative for Both Celiac Disease-Related Intestinal Damage and Serum Autoantibodies.

An unbalance between Abs that recognize an autoantigen (idiotypes; IDs) and Igs that bind such Abs (anti-IDs) is considered a functional event in autoimmune disorders. We investigated the presence of an ID/anti-ID network in celiac disease (CD), a condition in which antitissue transglutaminase 2 (TG2) Abs are suspected to contribute to CD pathogenesis. To characterize the ID side, we reproduced by in vitro yeast display the intestine-resident Abs from CD and control patients. These TG2-specific IDs were used to identify potential anti-IDs in the serum. We observed elevated titers of anti-IDs in asymptomatic patients with predisposition to CD and demonstrated that anti-ID depletion from the serum restores a detectable humoral response against TG2. Our study provides an alternative approach to quantify CD-related autoantibodies in cases that would be defined "negative serology" with current diagnostic applications. Therefore, we suggest that developments of this technology could be designed for perspective routine tests.

Serum anti-tissue transglutaminase antibodies detected during febrile illness may not be produced by the intestinal mucosa.

Anti-transglutaminase antibodies are the diagnostic marker of celiac disease, and are considered to be synthesized only by intestinal B-lymphocytes. During an infectious disease, these antibodies are transiently detected in serum. We show that these infection-triggered antibodies may not originate in the intestinal mucosa and are not an indication of celiac disease.

Cryptic genetic gluten intolerance revealed by intestinal antitransglutaminase antibodies and response to gluten-free diet.

BACKGROUND AND OBJECTIVE: Antitransglutaminase (anti-TG2) antibodies are synthesised in the intestine and their presence seems predictive of future coeliac disease (CD). This study investigates whether mucosal antibodies represent an early stage of gluten intolerance even in the absence of intestinal damage and serum anti-TG2 antibodies. METHODS: This study investigated 22 relatives of patients with CD genetically predisposed to gluten intolerance but negative for both serum anti-TG2 antibodies and intestinal abnormalities. Fifteen subjects were symptomatic and seven were asymptomatic. The presence of immunoglobulin A anti-TG2 antibodies in the intestine was studied by creating phage-antibody libraries against TG-2. The presence of intestinal anti-TG2 antibodies was compared with the serum concentration of the intestinal fatty acid-binding protein (I-FABP), a marker for early intestinal mucosal damage. The effects of a 12-month gluten-free diet on anti-TG2 antibody production and the subjects' clinical condition was monitored. Twelve subjects entered the study as controls. RESULTS: The intestinal mucosa appeared normal in 18/22; 4 had a slight increase in intraepithelial lymphocytes. Mucosal anti-TG2 antibodies were isolated in 15/22 subjects (68%); in particular symptomatic subjects were positive in 13/15 cases and asymptomatic subjects in 2/7 cases (p=0.01). No mucosal antibodies were selected from the controls' biopsies. There was significant correlation between the presence of intestinal anti-TG2 antibodies and positive concentrations of I-FABP (p=0.0008). After a gluten-free diet, 19/22 subjects underwent a second intestinal biopsy, which showed that anti-TG2 antibodies had disappeared in 12/15 (p=0.002), while I-FABP decreased significantly (p<0.0001). The diet resolved both extraintestinal and intestinal symptoms. CONCLUSIONS: A new form of genetic-dependent gluten intolerance has been described in which none of the usual diagnostic markers is present. Symptoms and intestinal anti-TG2 antibodies respond to a gluten free-diet. The detection of intestinal anti-TG2 antibodies by the phage-antibody libraries has an important diagnostic and therapeutic impact for the subjects with gluten-dependent intestinal or extraintestinal symptoms. Clinical trial number NCT00677495.

Regulatory T-cell function is impaired in celiac disease.

Celiac disease (CD) is characterized by intolerance to gluten and high risk of developing autoimmune phenomena. Possible defects in immune tolerance could have a role in the pathogenesis of the disease. As regulatory T-cells (Tregs) are the main population involved in maintaining peripheral tolerance, we investigated the number of these cells in celiac patients as compared with healthy donors. Moreover, we analyzed the suppressive function of CD4+CD25+ T-cells from celiac disease patients and controls on autologous responder T-cells (CD4+CD25-). The percentage of CD4+CD25+FOXP3+ cells was not different in celiacs and in healthy controls, and among positive cells the level of expression of the two regulatory markers was comparable. However, the suppressor activity of Tregs was significantly impaired in CD patients. These results suggest that a defect in Tregs function could play a role in the pathogenesis of CD and in CD-associated autoimmunity.

Uselessness of anti-actin antibody in celiac disease screening.

BACKGROUND: Serum anti-actin IgA antibodies (AAA) were identified in patients with celiac disease (CD), and a close correlation emerged between the presence of AAA and mucosa damage, but test for AAA found in celiacs have a wide range of sensitivity and specificity values. AIM: To compare 1) the sensitivity and specificity of untreated, calcium-chelated and heated sera from 102 celiacs, 52 sick patients and 103 healthy controls in the determination of AAA, and 2) the reliability of AAA with anti-transglutaminase antibodies (anti-tTG) in diagnosing celiac disease and in predicting intestinal damage. The intestinal derived AAA was isolated by using the phage-display library technique. RESULTS: Treated sera was significantly more sensitive than untreated (p=0.0001), and showed a significant correlation between AAA and the three degrees (3a, 3b, 3c) of intestinal damage (p=0.01). Sensitivity and specificity values of anti-tTG assay were higher than the AAA assay, and anti-tTG serum-concentration was only significantly correlated with more severe (3b and 3c) intestinal damage degrees. AAA isolated by phage display showed similar results of serum AAA in immunofluorescence assay. CONCLUSIONS: Notwithstanding correlation between AAA and celiac disease, AAA assay, also after treatments, has little to offer in screening for CD compared to the well-established anti-transglutaminase assay.

Pro inflammatory stimuli enhance the immunosuppressive functions of adipose mesenchymal stem cells-derived exosomes.

The predominant mechanism by which adipose mesenchymal stem cells (AMSCs) participate to tissue repair is through a paracrine activity and their communication with the inflammatory microenvironment is essential part of this process. This hypothesis has been strengthened by the recent discovery that stem cells release not only soluble factors but also extracellular vesicles, which elicit similar biological activity to the stem cells themselves. We demonstrated that the treatment with inflammatory cytokines increases the immunosuppressive and anti-inflammatory potential of AMSCs-derived exosomes, which acquire the ability to shift macrophages from M1 to M2 phenotype by shuttling miRNA regulating macrophages polarization. This suggests that the immunomodulatory properties of AMSCs-derived exosomes may be not constitutive, but are instead induced by the inflammatory microenvironment.

Heterozygous nucleotide-binding oligomerization domain-2 mutations affect monocyte maturation in Crohn's disease.

AIM: To investigate the function of monocytes in Crohn's disease (CD) patients and to correlate this with disease-associated nucleotide-binding oligomerization domain-2 (NOD2) gene variants. METHODS: Monocytes from 47 consecutively referred CD patients and 9 healthy blood donors were cultured with interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF), and stimulated with lipopolysaccharide (LPS) or muramyldipeptide (MDP), the putative ligand of NOD2. RESULTS: We found that monocytes from CD patients differentiated in vitro to mature dendritic cells (DCs), as determined by immunophenotype and morphology. NOD2 genotype was assessed in all subjects, and we observed high CD86 expression on immature and LPS-stimulated DCs in NOD2 mutated CD patients, as compared with wtNOD2 CD patients and controls. By contrast, CD86 expression levels of DCs induced to maturity with MDP derived from NOD2-mutated subjects were comparable to those of normal subjects. The amount of IL-12p70 in patient-cell cultures was larger than in controls after LPS treatment, but not after treatment with MDP. CONCLUSION: Our results suggest that DCs obtained from patients with mutations in the NOD2 gene display an activated phenotype characterized by high CD86 expression, but have a diminished response to MDP when compared to the terminal differentiation phase. We speculate that the altered differentiation of monocytes might lead to an imbalance between inflammation and the killing ability of monocytes, and may be relevant to the pathogenesis of CD.

An amperometric immunosensor for diagnosis of celiac disease based on covalent immobilization of open conformation tissue transglutaminase for determination of anti-tTG antibodies in human serum.

A new amperometric immunosensor based on the covalent immobilization of tissue transglutaminase enzyme in its open conformation (open-tTG) was developed and optimized for determination of anti-tissue transglutaminase antibodies (anti-tTG) in human serum. Experimental design allowed us to find the optimal conditions for quantification of both IgA and IgG isotypes of anti-tTG in order to assess suitability of the device for diagnostic purposes. The glassy carbon electrodic substrate was electrochemically functionalized with gold nanoparticles and subsequently derivatized with a self-assembled monolayer of 11-mercaptoundecanoic acid for the covalent anchoring of the enzyme. This step was performed under carefully controlled conditions in order to keep the open conformation of the tTG. The immunosensor showed good analytical performance with limit of detection levels (1.7 AU mL(-1) for IgA and 2.7 AU mL(-1) for IgG) below the diagnostic threshold value (3.0 AU mL(-1)) and inter-sensor reproducibility giving RSD lower than 10%. The developed sensor was validated in serum samples from pediatric patients for clinical applications, using two ELISA kits specific for the determination of anti-tTG IgA and IgG antibodies as reference methods; good recovery rates ranging from 74% to 117% were calculated.