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:To predict the outcomes of disseminated fungal disease, a deeper understanding of host-pathogen interactions at the site of infection is needed to identify targets for clinical intervention and diagnostic development. Cryptococcus neoformans is the causative agent of cryptococcosis, the largest infectious killer of individuals living with HIV. Cryptococcal infection begins in the lungs, with loss of immunological control leading to disseminated central nervous system disease and death. Using advanced mass spectrometry-based proteomic techniques, in vivo infection models, and patient-derived clinical strains, we explored the proteomic profiles of C. neoformans infections related to differences in strain virulence. Our findings reveal the non-lethal latent infection produces a proteomic response that drastically differs from those caused by lethal infections, and that the proteomic profiles of typical and hypervirulent infections are surprisingly similar despite differences in time-to-death.