IL-10-producing regulatory cells impact on celiac disease evolution.

Celiac Disease (CD) is a T-cell mediated disorder caused by immune response to gluten, although the mechanisms underlying CD progression are still elusive. We analyzed immune cell composition, plasma cytokines, and gliadin-specific T-cell responses in patients with positive serology and normal intestinal mucosa (potential-CD) or villous atrophy (acute-CD), and after gluten-free diet (GFD). We found: an inflammatory signature and the presence of circulating gliadin-specific IFN-γ+ T cells in CD patients regardless of mucosal damage; an increased frequency of IL-10-secreting dendritic cells (DC-10) in the gut and of circulating gliadin-specific IL-10-secreting T cells in potential-CD; IL-10 inhibition increased IFN-γ secretion by gliadin-specific intestinal T cells from acute- and potential-CD. On GFD, inflammatory cytokines normalized, while IL-10-producing T cells accumulated in the gut. We show that IL-10-producing cells are fundamental in controlling pathological T-cell responses to gluten: DC-10 protect the intestinal mucosa from damage and represent a marker of potential-CD.

Tolerogenic IL-10-engineered dendritic cell-based therapy to restore antigen-specific tolerance in T cell mediated diseases.

Tolerogenic dendritic cells play a critical role in promoting antigen-specific tolerance via dampening of T cell responses, induction of pathogenic T cell exhaustion and antigen-specific regulatory T cells. Here we efficiently generate tolerogenic dendritic cells by genetic engineering of monocytes with lentiviral vectors co-encoding for immunodominant antigen-derived peptides and IL-10. These transduced dendritic cells (designated DCIL-10/Ag) secrete IL-10 and efficiently downregulate antigen-specific CD4+ and CD8+ T cell responses from healthy subjects and celiac disease patients in vitro. In addition, DCIL-10/Ag induce antigen-specific CD49b+LAG-3+ T cells, which display the T regulatory type 1 (Tr1) cell gene signature. Administration of DCIL-10/Ag resulted in the induction of antigen-specific Tr1 cells in chimeric transplanted mice and the prevention of type 1 diabetes in pre-clinical disease models. Subsequent transfer of these antigen-specific T cells completely prevented type 1 diabetes development. Collectively these data indicate that DCIL-10/Ag represent a platform to induce stable antigen-specific tolerance to control T-cell mediated diseases.

Antibody Profile, Gene Expression and Serum Cytokines in At-Risk Infants before the Onset of Celiac Disease.

Immunological events that precede the development of villous atrophy in celiac disease (CeD) are still not completely understood. We aimed to explore CeD-associated antibody production (anti-native gliadin (AGA), anti-deamidated gliadin (DGP) and anti-tissue transglutaminase (anti-tTG)) in infants at genetic risk for CeD from the Italian cohorts of the PREVENT-CD and Neocel projects, as well as the relationship between antibody production and systemic inflammation. HLA DQ2 and/or DQ8 infants from families with a CeD case were followed from birth. Out of 220 at-risk children, 182 had not developed CeD by 6 years of age (CTRLs), and 38 developed celiac disease (CeD). The profiles of serum cytokines (INFγ, IL1ß, IL2, IL4, IL6, IL10, IL12p70, IL17A and TNFα) and the expression of selected genes (FoxP3, IL10, TGFß, INFγ, IL4 and IL2) were evaluated in 46 children (20 CeD and 26 CTRLs). Among the 182 healthy CTRLs, 28 (15.3%) produced high levels of AGA-IgA (AGA+CTRLs), and none developed anti-tTG-IgA or DGP-IgA, compared to 2/38 (5.3%) CeD infants (Chi Sq. 5.97, p = 0.0014). AGAs appeared earlier in CTRLs than in those who developed CeD (19 vs. 28 months). Additionally, the production of AGAs in CeD overlapped with the production of DGP and anti-tTG. In addition, gene expression as well as serum cytokine levels discriminated children who developed CeD from CTRLs. In conclusion, these findings suggest that the early and isolated production of AGA-IgA antibodies is a CeD-tolerogenic marker and that changes in gene expression and cytokine patterns precede the appearance of anti-tTG antibodies.

Bifidobacteria modulate immune response in pediatric patients with cow's milk protein allergy.

BACKGROUND: In children with an allergy to cow's milk proteins (CMA), the altered composition of intestinal microbiota influences the immune tolerance to milk proteins (CMP). This study aims to investigate the effect of probiotics on the phenotype and activation status of peripheral basophils and lymphocytes in a pediatric CMA cohort. METHODS: CMA children underwent 45 days of treatment with Bifidobacteria. The basophil degranulation and the immune phenotype of B cells, T helper cells, and regulatory T cells were analyzed in peripheral blood at diagnosis (T0), after a 45-day probiotic treatment (T1), and 45 days after the probiotic wash-out (T2). RESULTS: We observed in probiotic-treated CMA patients a decrease in naive T lymphocytes. Among the CD3+ cell subsets, both naive and activated CD4+ cells resulted markedly reduced after taking probiotics, with the lowest percentages at T2. A decreased basophil degranulation was observed in response to all analyzed CMP at T1 compared to T0. CONCLUSIONS: The probiotic treatment resulted in a decrease of circulating naive and activated CD4+ T cells, as well as degranulating basophils. These data suggest that the Bifidobacteria could have a beneficial effect in the modulation of oral tolerance to CMP. TRIAL REGISTRATION: ISRCTN69069358. URL of registration: https://www.isrctn.com/ISRCTN69069358 . IMPACT: Probiotic treatment with Bifidobacteria induces a reduction of both naive and activated circulating CD4+ T cells in pediatric patients with cow's milk allergy (CMA). The probiotic supplementation induces a decreased basophil degranulation. The immunological tolerance persists even after 45 days of the probiotic wash-out. Bifidobacteria in vivo supplementation down-modulates the activation of innate and adaptive immunity in pediatric patients with cow's milk allergy. Bifidobacteria contribute to the development of immune tolerance in CMA patients.

E40 glutenase detoxification capabilities of residual gluten immunogenic peptides in in vitro gastrointestinal digesta of food matrices made of soft and durum wheat.

Gluten degrading enzymes, which are commonly referred to as "glutenases," represent attractive candidates for the development of a pharmacological treatment of gluten related disorders, such as coeliac disease (CeD). Endoprotease-40 (E40), a novel glutenase secreted by the actinomycete Actinoallomurus A8 and recombinantly produced in S. lividans TK24, was shown to be active at pH 3 to 6 (optimum pH 5), resistant to pepsin and trypsin degradation, able to destroy immunotoxicity of both gliadin 33-mer peptide and whole proteins and to strongly reduce the response of specific T cells when added to gliadin in in vitro gastrointestinal digestion. This study aims to functionally assess the capabilities of Endoprotease-40 (E40) to detoxify residual gluten immunogenic peptides in gastrointestinal digesta of food matrices made of soft and durum wheat. The INFOGEST harmonized protocols were applied to the multicompartmental model of simulated human gastrointestinal digestion, for the quantitative assessment of residual gluten in liquid (beer) and solid (bread and pasta) foods, made of either soft or durum wheat. Proteomic and immunological techniques, and functional assays on intestinal T cell lines from celiac disease patients were used to identify gluten-derived immunogenic peptide sequences surviving in gastric and gastrointestinal digesta after the addition of E40 at increasing enzyme: wheat proteins ratios. During the gastric phase (2 h incubation time), the addition of E40 demonstrated an extensive (≥ 95%) dose-dependent detoxification of whole gluten in real food matrices. Overall, the residual gluten content was found at, or even below, the 20 ppm gluten-free threshold for soft and durum wheat-based food. Furthermore, unlike in untreated gastrointestinal digesta, none of the immunodominant α-gliadin peptides survived in E40-treated digesta. Traces of ω- and γ-gliadin derived immunogenic peptides were still detected in E40-treated digesta, but unable to stimulate celiac-intestinal T cells. In conclusion, E40 is a promising candidate for the oral enzymatic therapy of CeD, as a stand-alone enzyme being efficient along the complete gastrointestinal digestion of gluten.

Analytical and functional approaches to assess the immunogenicity of gluten proteins.

Gluten proteins are the causative agents of celiac disease (CD), a lifelong and worldwide spread food intolerance, characterized by an autoimmune enteropathy. Gluten is a complex mixture of high homologous water-insoluble proteins, characterized by a high content of glutamine and proline amino acids that confers a marked resistance to degradation by gastrointestinal proteases. As a consequence of that, large peptides are released in the gut lumen with the potential to activate inflammatory T cells, in CD predisposed individuals. To date, several strategies aimed to detoxify gluten proteins or to develop immunomodulatory drugs to recover immune tolerance to gluten are under investigation. This review overviews the state of art of both analytical and functional methods currently used to assess the immunogenicity potential of gluten proteins from different cereal sources, including native raw seed flours and complex food products, as well as drug-treated samples. The analytical design to assess the content and profile of gluten immunogenic peptides, described herein, is based on the oral-gastro-intestinal digestion (INFOGEST model) followed by extensive characterization of residual gluten peptides by proteomic and immunochemical analyses. These approaches include liquid chromatography-high-resolution mass spectrometry (LC-MS/MS) and R5/G12 competitive ELISA. Functional studies to assess the immune stimulatory capabilities of digested gluten peptides are based on gut mucosa T cells or peripheral blood cells obtained from CD volunteers after a short oral gluten challenge.

Intestinal Cellular Biomarkers of Mucosal Lesion Progression in Pediatric Celiac Disease.

Celiac disease (CD) is a chronic intestinal inflammation caused by gluten ingestion in genetically predisposed individuals. Overt-CD and potential-CD are the two main forms of gluten intolerance in pediatric patients with different grades of intestinal mucosa lesion and clinical management. For overt-CD patients the gluten-free diet is mandatory, while for potential-CD the dietary therapy is recommended only for those subjects becoming clinically symptomatic overtime. To date, specific early biomarkers of evolution to villous atrophy in potential-CD are lacking. We recently observed an expansion of TCRγδ+ T cells and a concomitant disappearance of IL4-producing T cells in the intestinal mucosa of overt-CD patients compared to potential-CD children, suggesting the involvement of these two cells subsets in the transition from potential-CD to overt-CD. In this study, we demonstrated that the intestinal densities of IL4+ T cells inversely correlated with TCRγδ+ T cell expansion (p < 0.005) and with the serum levels of anti-tissue transglutaminase antibodies (p < 0.01). The changes of these two cell subsets strongly correlated with mucosal lesions, according to the histological Marsh classification, as the transition from M0 to M3 lesions was associated with a significant reduction of IL4+ T cells (M0 vs. M1 p < 0.04, M0 vs. M3 p < 0.007) and an increase of TCRγδ+ T cells (M0 vs. M1 p < 0.05, M0 vs. M3 p < 0.0006). These findings strongly suggest that the detection of TCRγδ+ and IL4+ T cells could serve as cellular biomarkers of mucosal lesion and targets of novel immunomodulatory therapies for CD.

HLA class II genes in precision-based care of childhood diseases: what we can learn from celiac disease.

Celiac disease (CeD) is a chronic immuno-mediated enteropathy caused by dietary gluten with marked autoimmunity traits. The human leukocyte antigen (HLA) class II heterodimers represent the main predisposing factor, although environmental agents, as viral infection, gut microbiota, and dietary regimen, also contribute to CeD risk. These molecules are involved in autoimmunity as they present self-antigens to autoreactive T cells that have escaped the thymic negative selection. In CeD, the HLA class II risk alleles, DQA1*05-DQB1*02 and DQA1*03-DQB1*03, encode for DQ2.5 and DQ8 heterodimers, and, furthermore, disease susceptibility was found strictly dependent on the dose of these genes. This finding questioned how the expression of HLA-DQ risk genes, and of relative surface protein on antigen-presenting cells, might be relevant for the magnitude of anti-gluten inflammatory response in CeD patients, and impact the natural history of disease, its pathomechanisms, and compliance to dietary treatment. In this scenario, new personalized medical approaches will be desirable to support an early, accurate, and non-invasive diagnosis, and to define genotype-guided preventive and therapeutic strategies for CeD. To reach this goal, a stratification of genetic risk, disease outcome, and therapy compliance based on HLA genotypes, DQ2.5/DQ8 expression measurement and magnitude of T cell response to gluten is mandatory. IMPACT: This article revises the current knowledge on how different HLA haplotypes, carrying the DQ2.5/DQ8 risk alleles, impact the onset of CeD. This review discusses how the expression of susceptibility HLA-DQ genes can determine the risk assessment, outcome, and prevention of CeD. The recent insights on the environmental factors contributing to CeD in childhood are reviewed. This review discusses the use of HLA risk gene expression as a tool to support medical precision approaches for an early and non-invasive diagnosis of CeD, and to define genotype-guided preventive and therapeutic strategies.

Comparative Analysis of in vitro Digestibility and Immunogenicity of Gliadin Proteins From Durum and Einkorn Wheat.

Recent studies suggested that gliadin proteins from the ancient diploid einkorn wheat Triticum monococcum retained a reduced number of immunogenic peptides for celiac disease patients because of a high in vitro digestibility with respect to hexaploid common wheat. In this study, we compared the immunological properties of gliadins from two Triticum monococcum cultivars (Hammurabi and Norberto-ID331) with those of a Triticum durum cultivar (Adamello). Gliadins were digested by mimicking the in vitro gastrointestinal digestion process that includes the brush border membrane peptidases. Competitive ELISA, based on R5 monoclonal antibody, showed that gastrointestinal digestion reduced the immunogenicity of Triticum monococcum gliadins; conversely, the immunogenic potential of Triticum durum gliadins remained almost unchanged by the in vitro digestion. The immune stimulatory activity was also evaluated by detecting the IFN-γ production in gliadin-reactive T-cell lines obtained from the small intestinal mucosa of HLA-DQ2+ celiac disease patients. Interestingly, gastrointestinal digestion markedly reduced the capability of Triticum monococcum gliadins (p <0.05) of both cultivars to activate T cells, while it slightly affected the activity of Triticum durum. In conclusion, our results showed that Triticum durum was almost unaffected by the in vitro gastrointestinal digestion, while Triticum monococcum had a marked sensibility to digestion, thus determining a lower toxicity for celiac disease patients.

Increased frequency of regulatory T cells in pediatric inflammatory bowel disease at diagnosis: a compensative role?

BACKGROUND: Regulatory T cells (Tregs) play a critical role in maintaining immune homeostasis. We investigated two main types of Tregs, the CD4+FOXP3+ and IL-10+ Tr1, in pediatric subjects with inflammatory bowel disease (IBD) both at diagnosis and after the clinical remission. METHODS: Peripheral blood Tregs were analyzed in 16 children with Crohn's disease (CD), 19 with ulcerative colitis (UC), and 14 healthy controls (HC). Two cocktails of fluoresceinated antibodies were used to discriminate between CD4+FOXP3+ and Tr1. RESULTS: We observed in both CD and UC groups a higher frequency of Tr1 at diagnosis compared to controls, which decreased at follow-up compared to diagnosis, in particular in UC. Similarly, in UC patients the percentage of CD4+FOXP3+ Tregs markedly decreased at follow-up compared to the same patients at diagnosis and compared to HC. The expression of CTLA-4 in CD4+FOXP3+ Tregs increased in both groups at clinical remission. CONCLUSION: This study shows that IBD children present at diagnosis an increased frequency of circulating Tregs, probably as a compensative reaction to tissue inflammation. During the clinical remission, the Treg frequency diminishes, and concomitantly, their activation status increases. Notwithstanding, the high Treg density at diagnosis is not sufficient to counteract the inflammation in the childhood IBD.

The intestinal expansion of TCRγδ+ and disappearance of IL4+ T cells suggest their involvement in the evolution from potential to overt celiac disease.

Celiac disease (CD) is characterized by a spectrum of intestinal inflammatory lesions. Most patients have villous atrophy (overt-CD), while others have a morphologically normal mucosa, despite the presence of CD-specific autoantibodies (potential-CD). As the mechanism responsible for villous atrophy is not completely elucidated, we investigated biomarkers specific for the different celiac lesions. Phenotype and cytokine production of intestinal mucosa cells were analyzed by flow cytometry in gut biopsies of children with overt- or potential-CD and in healthy controls. Density of TCRγδ+ T cells was found markedly enhanced in intestinal mucosa of children with overt-CD compared to potential-CD or controls. By contrast, very few IL4+ T cells infiltrated the mucosa with villous atrophy compared to morphologically normal mucosa. IL4+ T cells were classical CD4+ T-helper cells (CD161- ), producing or not IFN-γ, and negative for IL17A. Our study demonstrated that the transition to villous atrophy in CD patients is characterized by increased density of TCRγδ+ T cells, and concomitant disappearance of IL4+ cells. These findings suggest that immunomodulatory mechanisms are active in potential-CD to counteract the inflammatory cascade responsible of villous atrophy. Further studies are required to validate the use of IL4+ and TCRγδ+ T cells as biomarkers of the different CD forms.

HLA-DQA1 and HLA-DQB1 Alleles, Conferring Susceptibility to Celiac Disease and Type 1 Diabetes, are More Expressed Than Non-Predisposing Alleles and are Coordinately Regulated.

HLA DQA1*05 and DQB1*02 alleles encoding the DQ2.5 molecule and HLA DQA1*03 and DQB1*03 alleles encoding DQ8 molecules are strongly associated with celiac disease (CD) and type 1 diabetes (T1D), two common autoimmune diseases (AD). We previously demonstrated that DQ2.5 genes showed a higher expression with respect to non-CD associated alleles in heterozygous DQ2.5 positive (HLA DR1/DR3) antigen presenting cells (APC) of CD patients. This differential expression affected the level of the encoded DQ2.5 molecules on the APC surface and established the strength of gluten-specific CD4+ T cells response. Here, we expanded the expression analysis of risk alleles in patients affected by T1D or by T1D and CD comorbidity. In agreement with previous findings, we found that DQ2.5 and DQ8 risk alleles are more expressed than non-associated alleles also in T1D patients and favor the self-antigen presentation. To investigate the mechanism causing the high expression of risk alleles, we focused on HLA DQA1*05 and DQB1*02 alleles and, by ectopic expression of a single mRNA, we modified the quantitative equilibrium among the two transcripts. After transfection of DR7/DR14 B-LCL with HLA-DQA1*05 cDNA, we observed an overexpression of the endogenous DQB1*02 allele. The DQ2.5 heterodimer synthesized was functional and able to present gluten antigens to cognate CD4+ T cells. Our results indicated that the high expression of alpha and beta transcripts, encoding for the DQ2.5 heterodimeric molecules, was strictly coordinated by a mechanism acting at a transcriptional level. These findings suggested that, in addition to the predisposing HLA-DQ genotype, also the expression of risk alleles contributed to the establishment of autoimmunity.

Structural model of the full-length Ser/Thr protein kinase StkP from S. pneumoniae and its recognition of peptidoglycan fragments.

The unique eukaryotic-like Ser/Thr protein kinases of Streptococcus pneumoniae, StkP, plays a primary role in the cell division process. It is composed of an intracellular kinase domain, a transmembrane helix and four extracellular PASTA subunits. PASTA domains were shown to interact with cell wall fragments but the key questions related to the molecular mechanism governing ligand recognition remain unclear. To address this issue, the full-length structural model of StkP was generated by combining small-angle X-ray scattering data with the results of computer simulations. Docking and molecular dynamics studies on the generated three-dimensional model structure reveal the possibility of peptidoglycan fragment binding at the hinge regions between PASTA subunits with a preference for a bent hinge between PASTA3 and PASTA4.

Cytokine production profile in intestinal mucosa of paediatric inflammatory bowel disease.

In the recent years, the incidence of inflammatory bowel disease (IBD) has dramatically increased in young subjects, however, the pathogenesis of paediatric IBD is poorly investigated. In this study we aimed to evaluate the cytokine pattern and the phenotype of cytokine producing cells in the intestinal mucosa of paediatric patients affected by Crohn's disease (CD) or ulcerative colitis (UC) and of non-IBD healthy controls (HC). Cytokine (IL-15, TNF-α, INF-γ) production was analyzed at basal condition and after mitogen stimulation either intracellularly by flow cytometry or in intestinal cell culture supernatants by enzyme-linked immunosorbent assay (ELISA). A higher frequency of enterocytes (EpCam+ cells) was observed in UC patients compared to CD or HC. An expansion of enterocytes producing IL-15 and TNF-α were found in IBD patients compared to HC. A marked expression of IL-15 in the intestinal epithelium of IBD patients was further confirmed by immunohistochemistry. Myeloid dendritic (CD11c+) cells producing TNF-α and INF-γ were increased in IBD biopsies. Unexpectedly, only after a strong mitogen stimulus, as phytohaemagglutinin, the frequency of CD3+ cells producing IFN-γ was increased in IBD compared to control intestinal mucosa. Interestingly, functional studies performed on organ cultures of intestinal biopsies with neutralizing anti-IL-15 monoclonal antibody showed a marked reduction of mononuclear cell activation, proliferation of crypt enterocytes, as well as a reduction of TNF-α release in organ culture supernatants. In conclusion, we found that in the gut mucosa of IBD children both enterocytes and dendritic cells produce proinflammatory cytokines. The over-expression of IL-15 by enterocytes in IBD intestine and the reduced IBD inflammation by IL-15 blockage suggests that this cytokine could be a therapeutic target in IBD.

The cross-talk between enterocytes and intraepithelial lymphocytes.

The gut mucosa is continuously exposed to food and microbial antigens. Both enterocytes and intraepithelial lymphocytes have a pivotal role in maintaining the integrity of intestinal mucosa, as these cells guarantee a first line of defense against pathogens and toxic molecules. Enterocytes maintain a physical barrier against microbes and directly contribute to the gut homeostasis by sampling the luminal agents through several pattern recognition receptors or presenting antigen to mucosa T cells. Similarly, due to a close physical contact with the intestinal epithelial cells, the intraepithelial lymphocytes represent an important part of the gut lymphoid tissue, contrasting the entry and spread of pathogens. An alteration of the cross-talk between intestinal epithelial cells and intraepithelial lymphocytes might actively contribute to the development of intestinal immune disorders, as occurring in patients with celiac disease. In genetically predisposed individuals, the gluten exposure results in a massive production of interleukin-15, activation of intraepithelial lymphocytes, and modification of small intestinal mucosa architecture and function. We will review the recent studies on the pathophysiology of cross-talk between enterocytes and intraepithelial T cells, and how this interaction is crucial for intestinal integrity and homeostasis.

In the Intestinal Mucosa of Children With Potential Celiac Disease IL-21 and IL-17A are Less Expressed than in the Active Disease.

OBJECTIVES: Potential celiac disease (CD) patients are at an increased risk to developing CD as indicated by positive CD-associated serology. We investigated in duodenal mucosa of such patients the presence of both IL-21 and IL-17A and the role of gliadin peptides and IL-15 in their expression. METHODS: Duodenal biopsies from 76 active CD, 90 potential CD, and 58 control patients were analyzed for IL-21 and/or IL-17A production by quantitative real-time PCR, immunohistochemistry, flow cytometry, and ELISA. The presence of IL-21 receptor was investigated by western blot. Potential CD duodenal fragments were cultured with gliadin peptides (PTG) and/or IL-15 and the expression/production of IL-21 and IL-17A assessed by quantitative real-time PCR and by immunohistochemistry. RESULTS: In potential CD, IL-21 was lower than in active CD, in terms of RNA expression (P<0.01), density of lamina propria (LP) IL-21(+) cells (P<0.05), and protein secretion (P<0.05). Also, IL-21R was weakly detectable in potential CD. Several LP cell types produced IL-21 in CD. In potential CD, CD4(+)IL-21(+) cells increased after PMA-ionomycin stimulation and co-produced IFN-γ but not IL-17A. After 24 hours of culture stimulation with PTG, IL-21-producing cells increased but not the ones producing IL-17A. This increase was further enhanced by the addition of IL-15 to culture medium. CONCLUSIONS: In potential CD, IL-21 is less expressed than in active CD; however, IL-21-producing cells are present and prone to respond after specific stimuli. This suggests a key role of IL-21 in the progression of mucosal damage in CD.

Bifidobacteria Enhance Antigen Sampling and Processing by Dendritic Cells in Pediatric Inflammatory Bowel Disease.

Bifidobacteria have been reported to reduce inflammation and contribute to intestinal homeostasis. However, the interaction between these bacteria and the gut immune system remains largely unknown. Because of the central role played by dendritic cells (DCs) in immune responses, we examined in vitro the effects of a Bifidobacteria mixture (probiotic) on DC functionality from children with inflammatory bowel disease. DCs obtained from peripheral blood monocytes of patients with Crohn's disease (CD), ulcerative colitis, and noninflammatory bowel disease controls (HC) were incubated with fluorochrome-conjugated particles of Escherichia coli or DQ-Ovalbumin (DQ-OVA) after a pretreatment with the probiotic, to evaluate DC phenotype, antigen sampling and processing. Moreover, cell supernatants were collected to measure tumor necrosis factor alpha, interferon gamma, interleukin 17, and interleukin 10 production by enzyme-linked immunosorbent assay. DCs from CD children showed a higher bacteria particles uptake and DQ-OVA processing after incubation with the probiotic; in contrast, DC from both ulcerative colitis and HC showed no significant changes. Moreover, a marked tumor necrosis factor alpha release was observed in DC from CD after exposure to E. coli particles, whereas the probiotic did not affect the production of this proinflammatory cytokine. In conclusion, the Bifidobacteria significantly improved the antigen uptake and processing by DCs from patients with CD, which are known to present an impaired autophagic functionality, whereas, in DCs from ulcerative colitis and HC, no prominent effect of probiotic mixture was observed. This improvement of antigen sampling and processing could partially solve the impairment of intestinal innate immunity and reduce uncontrolled microorganism growth in the intestine of children with inflammatory bowel disease.

Tolerogenic effect of mesenchymal stromal cells on gliadin-specific T lymphocytes in celiac disease.

BACKGROUND AIMS: Celiac disease is caused by a dysregulated immune response toward dietary gluten, whose only treatment is a lifelong gluten-free diet. We investigated the effects of mesenchymal stromal cells (MSCs) on gliadin-specific T cells, which are known to induce intestinal lesions, in view of a possible use as new therapy. METHODS: Bone marrow-derived MSCs and gliadin-specific T-cell lines were obtained from allogeneic donors and mucosal specimens of celiac patients, respectively. The immunosuppressant effect of MSCs was evaluated in terms of proliferative response and interferon (IFN)-γ production upon gliadin stimulation of long-term T-cell lines; the immunomodulant effect was assessed in terms of apoptotic rate, immunophenotype and cytokine profile of short-term T-cell lines generated in the presence of MSCs. Different MSC:T-cell ratios were applied, and statistics were performed as appropriate. RESULTS: MSCs inhibited both proliferative response and IFN-γ production of long-term T-cell lines in a dose-dependent manner while limiting the expansion of short-term T-cell lines by increasing the apoptotic rate. Moreover, a reduction of the CD4(+) population and expansion of the regulatory FoxP3+ subset were found in T-cell lines cultured with MSCs, in which a significant decrease of interleukin (IL)-21, IFN-γ and IL-10 paralleled by an upregulation of transforming growth factor-ß1, IL-6 and IL-8 were observed. Finally, an increase of the indoleamine 2,3-dioxygenase activity was found, possibly playing a key role in mediating these effects. CONCLUSIONS: MSCs exert potent immunomodulant effects on gliadin-specific T cells, which may be exploited for future therapeutic application in celiac disease.

Therapy against reperfusion-induced microvascular injury.

No-reflow, i.e., the lack of distal myocardial perfusion to fully recover following recanalization of an acutely occluded coronary artery, is not only a mere consequence of ischemic injury, as substantial microvascular alterations may also develop subsequently, after initial restoration of perfusion. Since part of perfusion impairment is secondary to events set in motion by reperfusion, this gives way to the possibility of preventing it through adequate interventions. Duration and severity of ischemia influence the occurrence of reperfusion-mediated no-reflow, since severity of ischemic injury sets the stage for events which actually unfold after restoration of blood flow. Proposed mechanisms of no-reflow are impaired vasodilation, intravascular thrombosis, and accumulation of neutrophils in the microvasculature, orchestrated by activation of vascular endothelium. Experimental studies have unraveled much of mechanisms of noreflow, and delineated possible ways of intervention. Despite successful experimental data, in the clinical setting results have been much less encouraging, and no drug can be currently recommended for routine use to prevent or treat microvascular injury and no-reflow in patients. Reperfusion-mediated impairment of microcirculation in postischemic hearts remains a challenges for investigators and clinicians alike. Large multicenter studies, specifically aimed at evaluating the effects of the more promising interventions (adenosine, nicorandil, statins, ACE inhibitors or angiotensin II receptor blockers) need to be designed and performed, to test the effect of these promising interventions on microvascular alterations during postischemic reflow, and their ability to improve tissue perfusion, myocardial function and prognosis in patients with acute myocardial infarction.