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Abstract: Vibrio cholerae, the etiological agent of cholera, leads to the induction of host cell nuclear responses and the activation of proinflammatory cytokines in the cultured intestinal epithelial cells. However, the host cell signaling pathway leading to proinflammatory response is not explored. In this study, we demonstrated that V. cholerae infection on intestinal epithelial cells results in the activation of extracellular signal-regulated kinases1/2(ERK1/2) and p38 of the mitogen activated protein kinase (MAPK) family. V. cholerae induced intracellular pathways in Int407 cells leading to the activation of protein kinase A (PKA) and protein tyrosin kinase (PTK) in upstream of MAPK and nuclear factor-kappaB (NF-κB) pathway. Inhibitor study of Ca2+ and phospholipase-gamma (PLC-γ) pathway suggested the possible involvement of Ca2+ signaling in the V. cholerae pathogenesis. V. cholerae culture supernatants as also insertional mutants of ctxA, toxR and toxT genes modulate the activation of MAPK and NF-κB signaling pathways. MAPK and NF-κB signaling pathway activation were also modulated by adherence and motility of V. cholerae. Studies with inhibitor of NF-κB, MAPK, PTK, PKA, PKC, Ca2+ and PLC pathways showed differential cytokine secretion in Int407 following V. cholerae infection. Therefore V. cholerae mediated induction of nuclear responses through signal transduction pathway and subsequent activation of proinflammatory cytokines in Int407 modulated by V. cholerae secretory factors, virulence, adhesion/motility which might explain some of its reactogenic mechanisms. [Copyright &y& Elsevier]

Abstract: During Vibrio vulnificus infection, V. vulnificus reaches the intestine and then invades the bloodstream by crossing the intestinal mucosal barrier of the host, which results in systemic septicemia. Previously, we reported that the RtxA toxin secreted through the RtxE transporter contributes to the cytotoxicity of V. vulnificus against intestinal epithelial cells. Here, we used gene mutants of rtxE and rtxA to determine the role that V. vulnificus RtxA toxin plays in the apoptotic death of human intestinal epithelial cells. The levels of DNA fragmentation were lower in human epithelial cells infected with an rtxE mutant of V. vulnificus than in those that were infected with the wild type. In addition, the rtxE mutant was found to induce lower levels of TUNEL positive cells and cell cycle arrest at the subG1 than the wild type V. vulnificus. Furthermore, the decreased levels of DNA fragmentation, TUNEL positive cells and subG1 arrest by the rtxE gene mutation were restored by the complementation of an rtxE gene into the rtxE mutant V. vulnificus. Finally, the rtxA mutant induced significantly lower levels of apoptotic cell death than the wild type. The levels of the PARP, cytochrome c, caspase-3, and mitochondrial membrane depolarization were lower in human epithelial cells infected with the rtxE and rtxA mutants, compared with the wild type and rtxE gene-complemented strains of V. vulnificus. Taken together, these results indicate that V. vulnificus RtxA toxin induces the apoptotic death through a mitochondria-dependent pathway in human intestinal epithelial cells exposed to V. vulnificus. [Copyright &y& Elsevier]

Abstract: Campylobacter (C.) jejuni and C. coli can cause gastrointestinal disorders in humans characterized by acute inflammation. Inflammatory signals are initiated during interaction between these pathogens and human intestinal cells, but nothing is known about the stimulation of avian intestinal cells by Campylobacter. Interleukin-8 (IL-8) as a proinflammatory chemokine plays an important role in mobilizing cellular defence mechanism. IL-8 mRNA expression in both human intestinal cells (INT 407) and primary intestinal chick cells (PIC) was determined by quantitative real-time RT-PCR. The secretion of IL-8 protein by INT407 was measured using ELISA. Although C. jejuni and C. coli are considered to be harmless commensals in the gut of birds, the avian Campylobacter isolates investigated were able to induce the proinflammatory IL-8 in PIC as well as in INT407. In an in vitro system, C. jejuni as well as C. coli were able to induce IL-8 mRNA in PIC. Relation between the virulence properties like toxin production, the ability to invade and to survive in Caco-2 cells and the level of IL-8 mRNA produced by INT 407 and PIC after infection with Campylobacter strains was also investigated. [Copyright &y& Elsevier]

Abstract: We have shown that the bacterial iron chelator, deferoxamine (DFO), triggers inflammatory signals, including the production of CXC chemokine IL-8, in human intestinal epithelial cells (IECs) by activating ERK1/2 and p38 kinase pathways. In the present study, we show that PKCδ, one of the novel protein kinase C (PKC) isoforms, involves in signal transduction pathways leading to DFO-induced IL-8 production. Pretreatment of human intestinal epithelial HT-29 cells with rottlerin showed remarkable inhibition of DFO-induced IL-8 production. In contrast, other PKC inhibitors such as Gö6976, Gö6983, GF109203X, and staurosporine revealed less or no inhibitory effects on DFO-induced IL-8 production, suggesting a potential role of PKCδ. Accordingly, DFO caused phosphorylation of PKCδ in the Thr505 and Ser643 residues in HT-29 cells. Transfection of dominant-negative PKCδ vector inhibited DFO-induced PKCδ phosphorylation as well as IL-8 promoter activity. In addition, suppression of endogenous PKCδ by siRNA significantly reduced DFO-induced IL-8 production. Collectively, these results suggest that PKCδ plays a pivotal role in signaling pathways leading to iron chelator-induced IL-8 production in human IECs. [Copyright &y& Elsevier]

Severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) is an unprecedented worldwide health problem that requires concerted and global approaches to stop the coronavirus 2019 (COVID-19) pandemic. Although SARS-CoV-2 primarily targets lung epithelium cells, there is growing evidence that the intestinal epithelium is also infected. Here, using both colon-derived cell lines and primary non-transformed colon organoids, we engage in the first comprehensive analysis of the SARS-CoV-2 life cycle in human intestinal epithelial cells (hIECs). Our results demonstrate that hIECs fully support SARS-CoV-2 infection, replication, and production of infectious de novo virus particles. We found that viral infection elicits an extremely robust intrinsic immune response where interferon-mediated responses are efficient at controlling SARS-CoV-2 replication and de novo virus production. Taken together, our data demonstrate that hIECs are a productive site of SARS-CoV-2 replication and suggest that the enteric phase of SARS-CoV-2 may participate in the pathologies observed in COVID-19 patients by contributing to increasing patient viremia and fueling an exacerbated cytokine response. • Human intestinal epithelium cells (hIECs) can be infected by SARS-CoV-2 • hIECs support SARS-CoV-2 replication and produce de novo viruses • SARS-CoV-2 infection can be controlled in hIECs by type I and III interferons Stanifer et al. find that SARS-CoV-2 could infect the human gastrointestinal tract and efficiently produce new viruses. Importantly, they find that the cytokines type I and III interferons, which are naturally made by cells in response to viral infection, are protective and could be used as an antiviral strategy. [ABSTRACT FROM AUTHOR]