Project description:Undernutrition increases susceptibility to diarrheal diseases. The adipocytokine leptin imparts protection from amebiasis. We tested the role of leptin signaling in cellular resistance to E. histolytica cytotoxicity in HEK cells transfected to express the leptin receptor. Protection from amebic killing was conferred by the leptin receptor. It required activation of the transcriptional regulator STAT3 by the leptin receptor, as mutation of the STAT3 activation domain of the receptor, or addition of a STAT3 small-molecule inhibitor, reversed protection. In contrast, a leptin receptor containing a common polymorphism (Q223R) known to increase susceptibility to amebiasis in humans provided significantly less protection. Consistent with the importance of STAT3, the Q223R polymorphism decreased l leptin-dependent STAT3 activation by 21% relative to the WT receptor (P=0.035). Microarray analysis identified potential downstream effectors of STAT3-mediated protection, most importantly TRIB1 and SOCS3, which appear to having opposing roles in the regulation of E. histolytica induced apoptosis. Together these data demonstrated that leptin increased the resistance of host cells to E. histolytica cytotoxicity via a STAT3-dependent mechanism. Additionally we found that the Q223R polymorphism in the leptin receptor, known to increase susceptibility to E. histolytica infection, decreased STAT3 activation and decreased host resistance to amebic cytotoxicity. This is the first demonstration of a host-signaling pathway that restricts amebic pathogenesis. Additionally, this finding represents an important advance in our mechanistic understanding of the role of leptin in the relationship between undernutrition and increased susceptibility to infection.
Project description:Resistance to amebiasis is associated with a polymorphism in the leptin receptor. Previous studies demonstrated that humans with the ancestral Q223 leptin receptor allele were nearly four times less likely to be infected with Entamoeba histolytica than those carrying the mutant R223 allele. We hypothesized that the Q223 allele protected against E. histolytica via STAT3-mediated transcription of genes required for mucosal immunity. To test this, mice containing the humanized LEPR Q or R allele at codon 223 were intracecally infected with E. histolytica. Susceptibility to amebiasis was assessed, and cecal tissues analyzed for changes in gene expression. By 72 h post-challenge all Q223 mice had cleared E. histolytica, whereas 39% of 223R mice were infected. 37 genes were differentially expressed in response to infection at 72 h, including pro-inflammatory genes (CXCL2, calprotectin (S100A8/9), Pla2g7, Itbg2, and MMP9) and functions pertaining to the movement and activity of immune cells. A comparison at 12 h post-challenge of infected Q223 vs. R223 mice identified a subset of differentially-expressed genes, many of which were closely linked to leptin signaling. Further analyses indicated that the Q223 gene expression pattern was consistent with a suppressed apoptotic response to infection, while 223R showed increased cellular proliferation and recruitment. These studies are the first to illuminate the downstream effects of leptin receptor polymorphisms on intestinal infection by E. histolytica. As such, they are important for the insight that they provide to this previously uncharacterized mechanism of mucosal immunity. Resistance to amebiasis is associated with a polymorphism in the leptin receptor. Previous studies demonstrated that humans with the ancestral Q223 leptin receptor allele were nearly four times less likely to be infected with Entamoeba histolytica than those carrying the mutant R223 allele. We hypothesized that the Q223 allele protected against E. histolytica via STAT3-mediated transcription of genes required for mucosal immunity. To test this, mice containing the humanized LEPR Q or R allele at codon 223 were intracecally infected with E. histolytica. Susceptibility to amebiasis was assessed, and cecal tissues analyzed for changes in gene expression. By 72 h post-challenge all Q223 mice had cleared E. histolytica, whereas 39% of 223R mice were infected. 37 genes were differentially expressed in response to infection at 72 h, including pro-inflammatory genes (CXCL2, calprotectin (S100A8/9), Pla2g7, Itbg2, and MMP9) and functions pertaining to the movement and activity of immune cells. A comparison at 12 h post-challenge of infected Q223 vs. R223 mice identified a subset of differentially-expressed genes, many of which were closely linked to leptin signaling. Further analyses indicated that the Q223 gene expression pattern was consistent with a suppressed apoptotic response to infection, while 223R showed increased cellular proliferation and recruitment. These studies are the first to illuminate the downstream effects of leptin receptor polymorphisms on intestinal infection by E. histolytica. As such, they are important for the insight that they provide to this previously uncharacterized mechanism of mucosal immunity. Control (non-infected QQ or RR) vs. infected with E. histolytica at two time points (12hour and 72 hour)
Project description:Resistance to amebiasis is associated with a polymorphism in the leptin receptor. Previous studies demonstrated that humans with the ancestral Q223 leptin receptor allele were nearly four times less likely to be infected with Entamoeba histolytica than those carrying the mutant R223 allele. We hypothesized that the Q223 allele protected against E. histolytica via STAT3-mediated transcription of genes required for mucosal immunity. To test this, mice containing the humanized LEPR Q or R allele at codon 223 were intracecally infected with E. histolytica. Susceptibility to amebiasis was assessed, and cecal tissues analyzed for changes in gene expression. By 72 h post-challenge all Q223 mice had cleared E. histolytica, whereas 39% of 223R mice were infected. 37 genes were differentially expressed in response to infection at 72 h, including pro-inflammatory genes (CXCL2, calprotectin (S100A8/9), Pla2g7, Itbg2, and MMP9) and functions pertaining to the movement and activity of immune cells. A comparison at 12 h post-challenge of infected Q223 vs. R223 mice identified a subset of differentially-expressed genes, many of which were closely linked to leptin signaling. Further analyses indicated that the Q223 gene expression pattern was consistent with a suppressed apoptotic response to infection, while 223R showed increased cellular proliferation and recruitment. These studies are the first to illuminate the downstream effects of leptin receptor polymorphisms on intestinal infection by E. histolytica. As such, they are important for the insight that they provide to this previously uncharacterized mechanism of mucosal immunity. Resistance to amebiasis is associated with a polymorphism in the leptin receptor. Previous studies demonstrated that humans with the ancestral Q223 leptin receptor allele were nearly four times less likely to be infected with Entamoeba histolytica than those carrying the mutant R223 allele. We hypothesized that the Q223 allele protected against E. histolytica via STAT3-mediated transcription of genes required for mucosal immunity. To test this, mice containing the humanized LEPR Q or R allele at codon 223 were intracecally infected with E. histolytica. Susceptibility to amebiasis was assessed, and cecal tissues analyzed for changes in gene expression. By 72 h post-challenge all Q223 mice had cleared E. histolytica, whereas 39% of 223R mice were infected. 37 genes were differentially expressed in response to infection at 72 h, including pro-inflammatory genes (CXCL2, calprotectin (S100A8/9), Pla2g7, Itbg2, and MMP9) and functions pertaining to the movement and activity of immune cells. A comparison at 12 h post-challenge of infected Q223 vs. R223 mice identified a subset of differentially-expressed genes, many of which were closely linked to leptin signaling. Further analyses indicated that the Q223 gene expression pattern was consistent with a suppressed apoptotic response to infection, while 223R showed increased cellular proliferation and recruitment. These studies are the first to illuminate the downstream effects of leptin receptor polymorphisms on intestinal infection by E. histolytica. As such, they are important for the insight that they provide to this previously uncharacterized mechanism of mucosal immunity.
Project description:Ten-eleven translocation (TET) 2 is an enzyme that catalyzes DNA demethylation to regulate gene expression by oxidizing 5-methylcytosine to 5-hydroxymethylcytosine, functioning as an essential epigenetic regulator in various biological processes. However, the regulation and function of TET2 in adipocytes during obesity are poorly understood. In this study, we demonstrate that leptin, a key adipokine in mammalian energy homeostasis regulation, suppresses adipocyte TET2 levels via JAK2-STAT3 signaling. Adipocyte Tet2 deficiency protects against high-fat diet-induced weight gain by reducing leptin levels and further improving leptin sensitivity. By interacting with C/EBPα, adipocyte TET2 increases the hydroxymethylcytosine levels of the leptin gene promoter, thereby promoting leptin gene expression. A decrease in adipose TET2 is associated with obesity-related hyperleptinemia in humans. Inhibition of TET2 suppresses the production of leptin in mature human adipocytes.Our findings support the existence of a negative feedback loop between TET2 and leptin in adipocytes and reveal a novel compensatory mechanism for the body to counteract the metabolic dysfunction caused by obesity.
Project description:To investigate the mechanism underlying effects of hAdMSC-CM on BAC-induced cytotoxicity, inflammation, and barrier dysfunction in human corneal epithelial cells. We confirmed that the the effects of hAdMSC-CM were associated with the TGFβ and JAK-STAT signalling pathways.
Project description:Activation of the immune system is a way for host tissue to defend itself against tumor growth. Hence, treatment strategies that are based on immunomodulation are on the rise. Conventional cytostatic drugs such as the anthracycline doxorubicin can also activate immune cell functions of macrophages and natural killer cells. In addition, cytotoxicity of doxorubicin can be enhanced by combining this drug with the cytokine IFN-alpha. Although doxorubicin is one of the most applied cytostatics, the molecular mechanisms of its immunomodulation ability are not investigated thoroughly. In microarray analyses of HeLa cells, a set of 19 genes related to interferon signaling was significantly overrepresented among genes regulated by doxorubicin exposure including STAT-1, -2, IRF9, NMI, and caspase 1. Regulation of these genes by doxorubicin was verified with Real-Time PCR and immunoblotting. An enhanced secretion of IFN-alpha was observed when HeLa cells were exposed to doxorubicin as compared to untreated cells. IFN-alpha neutralizing antibodies and inhibitors of JAK-STAT signaling (ATA and AG490) significantly abolished doxorubicin-stimulated expression of interferon signaling-related genes. Furthermore, inhibition of JAK-STAT signaling significantly reduced doxorubicin induced caspase 3 activation and desensitized HeLa cells to doxorubicin cytotoxicity. In conclusion, we demonstrate that doxorubicin induces interferon-responsive genes via IFN-alpha-JAK-STAT1 signaling and that this pathway is relevant for doxorubicinM-bM-^@M-^Ys cytotoxicity in HeLa cells. As immunomodulation is a promising strategy in anticancer treatment, this novel mode of action of doxorubicin may help to further improve the use of this drug among different types of anticancer treatment strategies. One batch of HeLa Cell culture treated with doxorubicin and DMSO (control) were used for screening of global changes at the transcriptome level.
Project description:Investigations of human parasitic diseases depend on the availability of appropriate in vivo animal models and ex vivo experimental systems, and are particularly difficult for pathogens whose exclusive natural hosts are humans, as for Entamoeba histolytica, the protozoan parasite responsible for amoebiasis. We elaborated a human hepatic in vitro model consisting of cultured liver sinusoidal endothelial cells and hepatocytes in a 3D collagen-I environment. We have characterized the model's barrier function, its chemical and structural complexity and examined E. histolytica invasion. This study deals with secretome of hepatic model under various invasion conditions.
Project description:The ability of Entamoeba histolytica to phagocytose host cells correlates to observed virulence in vivo. To better understand the mechanism of phagocytosis we used paramagnetic beads coated with host ligand and sorted trophozoites based on phagocytic ability. Gene expression was then measured in both the sorted phagocytic and non-phagocytic populations using a custom Affymetrix chip for E. histolytica. Feed forward regulation of phagocytosis by Entamoeba histolytica. Infection and Immunity. PMID 23045476
Project description:Central leptin action is sufficient to restore euglycemia in type 1 diabetes via an insulin-independent manner. To examine the mechanism in the hypothalamus at the transcription level, numerous genes that showed expression changes to STZ-induced type 1 diabetes and were reversed by central leptin action were identified.