Project description:Hepatic acute phase proteins control innate immune responses during infection by promoting myeloid derived suppressor cell function
Project description:Acute phase proteins (APPs) are an evolutionarily conserved family of proteins produced mainly in the liver in response to infection and inflammation. Despite vast pro- and anti-inflammatory properties ascribed to individual APPs, their collective function during infections remains poorly defined. Using a murine model for polymicrobial sepsis we show here that abrogation of APP production by hepatocyte-specific gp130 deletion, the signaling receptor shared by IL-6-family cytokines, dramatically increased mortality despite normal bacterial clearance. Hepatic gp130 signaling through signal transducer and activator of transcription (Stat)3 was required to control systemic inflammation. Notably, hepatic gp130/Stat3 activation was also a prerequisite to facilitate mobilization and tissue accumulation of myeloid-derived suppressor cells (MDSCs), a cell population mainly known for anti-inflammatory properties in cancer. We show that MDSCs were critical to regulate innate inflammation and their adoptive transfer efficiently protected gp130-deficient mice from sepsis-associated mortality. We identified serum amyloid A and Cxcl-1/KC as hepatic acute phase genes that cooperatively promoted MDSC mobilization, accumulation and survival. Administration of these proteins efficiently elevated MDSC numbers and reversed dysregulated inflammation and restored survival of gp130-deficient mice. Thus, gp130-dependent communication between the liver and MDSCs through acute phase proteins critically controls inflammatory responses during infection. Control [gp130f/f] and liver-specific Gp130 knockout [gp130delta(hepa)] mice were subjected to polymicrobial sepsis. Twelve hours after induction of sepsis mice were sacrificed and livers were removed. For control treatment mice were sacrified without any prior treatment. Total RNA was isolated and subjected to gene expression profiling.
Project description:Acute phase proteins (APPs) are an evolutionarily conserved family of proteins produced mainly in the liver in response to infection and inflammation. Despite vast pro- and anti-inflammatory properties ascribed to individual APPs, their collective function during infections remains poorly defined. Using a murine model for polymicrobial sepsis we show here that abrogation of APP production by hepatocyte-specific gp130 deletion, the signaling receptor shared by IL-6-family cytokines, dramatically increased mortality despite normal bacterial clearance. Hepatic gp130 signaling through signal transducer and activator of transcription (Stat)3 was required to control systemic inflammation. Notably, hepatic gp130/Stat3 activation was also a prerequisite to facilitate mobilization and tissue accumulation of myeloid-derived suppressor cells (MDSCs), a cell population mainly known for anti-inflammatory properties in cancer. We show that MDSCs were critical to regulate innate inflammation and their adoptive transfer efficiently protected gp130-deficient mice from sepsis-associated mortality. We identified serum amyloid A and Cxcl-1/KC as hepatic acute phase genes that cooperatively promoted MDSC mobilization, accumulation and survival. Administration of these proteins efficiently elevated MDSC numbers and reversed dysregulated inflammation and restored survival of gp130-deficient mice. Thus, gp130-dependent communication between the liver and MDSCs through acute phase proteins critically controls inflammatory responses during infection.
Project description:Myeloid-derived suppressor cells (MDSC) represent a heterogeneous population of immature myeloid cells that accumulate in blood, liver, spleen and tumors upon chronic inflammation and tumor development in patients and mice. Acute hepatitis is characterized by a fast infiltration of inflammatory cells in the liver and increased enzymatic activity at this organ that could lead into liver fibrosis and cirrhosis. We have studied the biology of hepatic MDSC in acute hepatitis. Unexpectedly, hepatic MDSC, which accumulate in the liver of mice bearing subcutaneous tumors, failed to suppress inflammatory responses upon Con A injection, but instead were responsible for exacerbating acute liver damage. Phenotypic, genetic and functional studies demonstrated rapid changes of hepatic MDSC from a suppressor phenotype into a pro-inflammatory subset as early as 3 hours after Con A injection. An increase in the expression of pro-inflammatory cytokines, costimulatory molecules such as CD80, CD86 and CD40 along with a loss of suppressor function was noticed in mice upon Con A treatment. These changes were CD40-dependent and not found in CD40-/- MDSC. Interestingly, CD40 ligation of human MDSC in vitro resulted in down-regulation of arginase I expression and suppressor function. Finally, blockade of ROS production in hepatic MDSC ameliorated hepatocyte damage suggesting that MDSC mediated toxicity was ROS dependent. We believe that these findings reflect how MDSC plasticity can be modulated to promote inflammation, opening a new path for therapies targeting innate suppressive cells in cancer patients. EL4 tumors were established in C57BL/6 mice, then mice were injected either with PBS (n=3) or 12.5mg/kg Con A (n=3). Three hours later mice were sacrificed, liver CD11b+Gr-1+ cells were sorted and samples were processed for gene expression analysis.
Project description:Myeloid-derived suppressor cells (MDSC) represent a heterogeneous population of immature myeloid cells that accumulate in blood, liver, spleen and tumors upon chronic inflammation and tumor development in patients and mice. Acute hepatitis is characterized by a fast infiltration of inflammatory cells in the liver and increased enzymatic activity at this organ that could lead into liver fibrosis and cirrhosis. We have studied the biology of hepatic MDSC in acute hepatitis. Unexpectedly, hepatic MDSC, which accumulate in the liver of mice bearing subcutaneous tumors, failed to suppress inflammatory responses upon Con A injection, but instead were responsible for exacerbating acute liver damage. Phenotypic, genetic and functional studies demonstrated rapid changes of hepatic MDSC from a suppressor phenotype into a pro-inflammatory subset as early as 3 hours after Con A injection. An increase in the expression of pro-inflammatory cytokines, costimulatory molecules such as CD80, CD86 and CD40 along with a loss of suppressor function was noticed in mice upon Con A treatment. These changes were CD40-dependent and not found in CD40-/- MDSC. Interestingly, CD40 ligation of human MDSC in vitro resulted in down-regulation of arginase I expression and suppressor function. Finally, blockade of ROS production in hepatic MDSC ameliorated hepatocyte damage suggesting that MDSC mediated toxicity was ROS dependent. We believe that these findings reflect how MDSC plasticity can be modulated to promote inflammation, opening a new path for therapies targeting innate suppressive cells in cancer patients.
Project description:V-domain immunoglobulin suppressor of T-cell activation (VISTA) has emerged as a unique immunoregulatory receptor on cells of the myeloid lineage. Agonizing VISTA on myeloid cells has recently been demonstrated to have a profound effect on dampening inflammatory responses. VISTA has been proposed to function both as a ligand and as a receptor, yet the role of VISTA as a ligand has been largely ignored. In this experiment, macrophages and neutrophils were isolated from mice and treated with LPS and VISTA to examine the effect of VISTA in dampening acute inflammation.
Project description:<p>Patients with myeloid malignancies bearing high-risk cytogenetic abnormalities lack effective therapies and have a poor overall survival. -7/del(7q) is identified in half of high-risk myeloid neoplasms. We recently identified <i>CUX1</i> to be a haploinsufficient myeloid tumor suppressor gene located within the commonly deleted segment of 7q22. Here we identify the spectrum of somatic mutations that co-occur with loss of <i>CUX1</i> and chromosome 7 in patients with <i>de novo</i> acute myeloid leukemia (AML) or a therapy-related myeloid neoplasm. -7/del(7q) leukemias have a distinct mutational profile characterized by low frequencies of alterations in major leukemogenic pathways, including genes encoding transcription factors, cohesin, and DNA-methylation-related proteins. In contrast, RAS pathway activating mutations occurred in 40% of -7/del(7q) samples, a significantly higher frequency than other AMLs and higher than previously reported. As targeted therapeutics advance, our data provide guidance for which pathways are most relevant in the treatment of adverse-risk myeloid leukemia. </p>
Project description:A common response to physiological duress is the hepatic acute phase response, a process during which the expression of many genes is altered in the liver. Amongst these transcripts are those encoding acute phase proteins, defined as circulating proteins with significantly changed concentrations during an acute phase response. The goal of this study was to determine the influence of STAT3 on hepatic gene changes including but not limited to acute phase proteins during bacterial pneumonia. Using the Cre-LoxP system, mice were generated with functional deletion of STAT3 in hepatocytes. In mutant mice, Cre-recombinase was expressed under transcriptional control of an albumin promoter in the presence of homozygous floxed alleles for STAT3. Wild-type control mice lacked the Cre-recombinase transgene. Microarray analysis was performed on liver RNA collected from both genotypes of mice in the absence and presence of pneumococcal pneumonia.
Project description:A common response to physiological duress is the hepatic acute phase response, a process during which the expression of many genes is altered in the liver. Amongst these transcripts are those encoding acute phase proteins, defined as circulating proteins with significantly changed concentrations during an acute phase response. The goal of this study was to determine the influence of NF-kappaB RelA (p65) on hepatic gene changes including but not limited to acute phase proteins during bacterial pneumonia. Using the Cre-LoxP system, mice were generated with functional deletion of NF-kappaB RelA (p65) in hepatocytes. In mutant mice, Cre-recombinase was expressed under transcriptional control of an albumin promoter in the presence of homozygous floxed alleles for RelA. Wild-type control mice lacked the Cre-recombinase transgene. Microarray analysis was performed on liver RNA collected from both genotypes of mice in the absence and presence of pneumococcal pneumonia.
Project description:A common response to physiological duress is the hepatic acute phase response, a process during which the expression of many genes is altered in the liver. Amongst these transcripts are those encoding acute phase proteins, defined as circulating proteins with significantly changed concentrations during an acute phase response. The goal of this study was to determine the influence of two transcription factors, STAT3 and NF-kappaB p65 (RelA), on hepatic gene changes including but not limited to acute phase proteins during bacterial pneumonia. Using the Cre-LoxP system, mice were generated with combined functional deletions of both STAT3 and RelA in hepatocytes. In mutant mice, Cre-recombinase was expressed under transcriptional control of an albumin promoter in the presence of homozygous floxed alleles for both STAT3 and RelA. Wild-type control mice lacked the Cre-recombinase transgene. Microarray analysis was performed on liver RNA collected from both genotypes of mice in the absence and presence of pneumococcal pneumonia.