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Background and aimType I interferons (IFNs) are highly expressed in the gut mucosa of celiac disease (CD) gut mucosa and stimulates immune response prompted by gluten ingestion, but the processes that maintain the production of these inflammatory molecules are not well understood. Adenosine deaminase acting on RNA 1 (ADAR1), an RNA-editing enzyme, plays a crucial role in inhibiting self or viral RNAs from activating auto-immune mediated responses, most notably within the type-I IFN production pathway. The aim of this study was to assess whether ADAR1 could contribute to the induction and/or progression of gut inflammation in patients with celiac disease.Material and methodsADAR1 expression was assessed by Real time PCR and Western blotting in duodenal biopsy taken from inactive and active celiac disease (CD) patients and normal controls (CTR). To analyze the role of ADAR1 in inflamed CD mucosa, lamina propria mononuclear cells (LPMC) were isolated from inactive CD and ADAR1 was silenced in with a specific antisense oligonucleotide (AS) and then incubated with a synthetic analogue of viral dsRNA (poly I:C). IFN-inducing pathways (IRF3, IRF7) in these cells were evaluated with Western blotting and inflammatory cytokines were evaluated with flow cytometry. Lastly, the role of ADAR1 was investigated in a mouse model of poly I:C-driven small intestine atrophy.ResultsReduced ADAR1 expression was seen in duodenal biopsies compared to inactive CD and normal controls. Ex vivo organ cultures of duodenal mucosal biopsies, taken from inactive CD patients, stimulated with a peptic-tryptic digest of gliadin displayed a decreased expression of ADAR1. ADAR1 silencing in LPMC stimulated with a synthetic analogue of viral dsRNA strongly boosted the activation of IRF3 and IRF7 and the production of type-I IFN, TNF-α and IFN-γ. Administration of ADAR1 antisense but not sense oligonucleotide to mice with poly I:C-induced intestinal atrophy, significantly increased gut damage and inflammatory cytokines production.ConclusionsThese data show that ADAR1 is an important regulator of intestinal immune homeostasis and demonstrate that defective ADAR1 expression could provide to amplifying pathogenic responses in CD intestinal mucosa.

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease. Although genetic factors confer susceptibility to the disease, only 15 % of the genetic contribution has been identified. TRAF3IP2 gene, associated with susceptibility to psoriatic arthritis and psoriasis, encodes for Act1, a negative regulator of adaptive immunity and a positive signaling adaptor in IL-17-mediated immune responses. The aim of this study was to assess the role of TRAF3IP2 gene variability in SLE susceptibility and disease phenotype in an Italian population. Two hundred thirty-nine consecutive SLE patients were enrolled. Study protocol included complete physical examination; the clinical and laboratory data were collected. Two hundred seventy-eight age- and ethnicity-matched healthy subjects served as controls. TRAF3IP2 polymorphisms (rs33980500, rs13190932, and rs13193677) were analyzed in both cases and controls. Genotype analysis was performed by allelic discrimination assays. A case-control association study and a genotype-phenotype correlation were performed. The rs33980500 and rs13193677 resulted significantly associated with SLE susceptibility (P = 0.021, odds ratio (OR) = 1.71, and P = 0.046, OR = 1.73, respectively). All three TRAF3IP2 single nucleotide polymorphisms resulted associated with the development of pericarditis; in particular, rs33980500 showed the strongest association (P = 0.002, OR 2.59). This association was further highlighted by binary logistic regression analysis. In conclusion, our data show for the first time the contribution of TRAF3IP2 genetic variability in SLE susceptibility, providing further suggestions that common variation in genes that function in the adaptive and innate arms of the immune system are important in establishing SLE risk. Our study also shows that this gene may affect disease phenotype and, particularly, the occurrence of pericarditis.

Purpose: The partial ineffectiveness and side effects of inflammatory bowel disease (IBD) current therapies drive basic research to look for new therapeutic target in order to develop new drug lead. Considering the pivotal role played by toll-like receptors (TLRs) in gut inflammation, we evaluate here the therapeutic effect of the synthetic glycolipid TLR4 antagonist FP7. Methods: The anti-inflammatory effect of FP7, active as TLR4 antagonist, was evaluated on peripheral blood mononuclear cells (PBMCs) and lamina propria mononuclear cells (LPMCs) isolated from IBD patients, and in a mouse model of ulcerative colitis. Results: FP7 strongly reduced the inflammatory responses induced by lipopolysaccharide (LPS) in vitro, due to its capacity to compete with LPS for the binding of TLR4/MD-2 receptor complex thus inhibiting both the MyD88- and TRIF-dependent inflammatory pathways. Colitic mice treated with FP7 exhibit reduced colonic inflammation and decreased levels of pro-inflammatory cytokines. Conclusions: This study suggests that TLR4 chemical modulation can be an effective therapeutic approach to IBD. The selectivity of FP7 on TLR4 makes this molecule a promising drug lead for new small molecules-based treatments.

Background & Aims The fragile X mental retardation protein (FMRP) affects multiple steps of the mRNA metabolism during brain development and in different neoplastic processes. However, the contribution of FMRP in colon carcinogenesis has not been investigated. Methods FMR1 mRNA transcript and FMRP protein expression were analyzed in human colon samples derived from patients with sporadic colorectal cancer (CRC) and healthy subjects. We used a well-established mouse model of sporadic CRC induced by azoxymethane to determine the possible role of FMRP in CRC. To address whether FMRP controls cancer cell survival, we analyzed cell death pathway in CRC human epithelial cell lines and in patient-derived colon cancer organoids in presence or absence of a specific FMR1 antisense oligonucleotide or siRNA. Results We document a significant increase of FMRP in human CRC relative to non-tumor tissues. Next, using an inducible mouse model of CRC, we observed a reduction of colonic tumor incidence and size in the Fmr1 knockout mice. The abrogation of FMRP induced spontaneous cell death in human CRC cell lines activating the necroptotic pathway. Indeed, specific immunoprecipitation experiments on human cell lines and CRC samples indicated that FMRP binds receptor-interacting protein kinase 1 (RIPK1) mRNA, suggesting that FMRP acts as a regulator of necroptosis pathway through the surveillance of RIPK1 mRNA metabolism. Treatment of human CRC cell lines and patient-derived colon cancer organoids with the FMR1 antisense resulted in up-regulation of RIPK1. Conclusions Altogether, these data support a role for FMRP in controlling RIPK1 expression and necroptotic activation in CRC., Graphical abstract

Background and Aim: In Crohn’s disease [CD], the pathological process is driven by an excessive immune response that is poorly counterbalanced by regulatory mechanisms. One such a mechanism involves aryl hydrocarbon receptor [AhR], a transcription factor that delivers protective signals in the gut. Expression of AhR is reduced in CD lamina propria mononuclear cells [LPMC] even though factors accounting for such a defect remain unknown. Since CD LPMC express elevated levels of Smad7, an inhibitor of transforming growth factor beta 1 [TGF-β1] activity, and TGF-β1 regulates AhR in other systems, we examined the link between AhR and Smad7 in the gut. Methods: AhR and interleukin [IL]-22 were evaluated in normal LPMC stimulated with TGF-β1 and 6-formylindolo[3,2-b]carbazole [Ficz], an activator of AhR, and in CD LPMC incubated with a Smad7 antisense oligonucleotide and then stimulated with Ficz and TGF-β1. AhR and IL-22 expression was evaluated in LPMC of Smad7-transgenic mice. Finally, we evaluated the protective effect of Ficz on colitis in RAG1 mice injected with naive or Smad7-overexpressing T cells. Results: In normal LPMC, TGF-β1 induced AhR and this event was associated with increased production of IL-22 following stimulation with Ficz. Treatment of CD LPMC with Smad7 antisense oligonucleotide enabled TGF-β1 to enhance AhR expression. Consistently, AhR expression and Ficz-induced IL-22 production were markedly reduced in T cells of Smad7-transgenic mice. In RAG1 mice, Ficz ameliorated colitis induced by wild type T cells but did not affect colitis induced by transfer of Smad7-overexpressing T cells. Conclusions: The inverse correlation between Smad7 and AhR expression helps to propagate inflammatory signals in the gut.

[This corrects the article DOI: 10.3389/fimmu.2023.1175348.]., (Copyright © 2023 Di Fusco, Segreto, Iannucci, Maresca, Franzè, Di Maggio, Di Grazia, Boccanera, Laudisi, Marafini, Paoluzi, Michienzi, Monteleone and Monteleone.)