Unknown,Transcriptomics,Genomics,Proteomics

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Hepatic acute phase proteins control innate immune responses during infection by promoting myeloid derived suppressor cell function

ABSTRACT: 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.

ORGANISM(S): Mus musculus

SUBMITTER: Uta Dierssen

PROVIDER: E-GEOD-22009 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Hepatic acute-phase proteins control innate immune responses during infection by promoting myeloid-derived suppressor cell function.

Sander Leif E LE Sackett Sara Dutton SD Dierssen Uta U Beraza Naiara N Linke Reinhold P RP Müller Michael M Blander J Magarian JM Tacke Frank F Trautwein Christian C

The Journal of experimental medicine 20100607 7

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 antiinflammatory properties ascribed to individual APPs, their collective function during infections remains poorly defined. Using a mouse model of polymicrobial sepsis, we show that abrogation of APP production by hepatocyte-specific gp130 deletion, the signaling receptor shared by IL-6 family cytokines, strongly increased m ...[more]

PMID: 20530204

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Project description:Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells that accumulate in the tumor microenvironment of most cancer patients. There MDSCs suppress both adaptive and innate immune responses, hindering immunotherapies. Moreover, many cancers are accompanied by inflammation, a processes that further intensifies MDSC suppressive activity, causing aggressive tumor progression and metastasis. MDSCs collected from tumor-bearing mice profusely release nano-scale membrane-bound extracellular vesicles, called exosomes, which carry biologically active proteins between cells and contribute directly to the immune suppressive functions of MDSC. Many studies on other cell types have shown that exosomes may also carry microRNAs (miRNAs) and messenger RNAs (mRNAs) which can also be transferred to surrounding and distant cells. However, to the best of our knowledge, the miRNA and mRNA cargo of MDSC-derived exosomes has not yet been interrogated. This study aims to identify and quantify the cargo of MDSC and their immunosuppressive exosomes to gather knowledge that can offer insights on the mechanisms by which MDSCs contribute to immune suppression, focusing on the role of exosomes as intercellular communication mediators in the tumor microenvironment. In order to achieve our objective a well-established mouse model based on a conventional mammary carcinoma (4T1 cells) and heightened inflammation (4T1 transduced to express the cytokine interleukin-1b) was used. We provide evidence that MDSC-derived exosomes carry proteins, mRNAs and miRNAs. Relative quantitation demonstrated quantitative differences between the exosome cargo and the cargo of their parental cells, supporting the hypothesis that selective loading into the exosomes is possible. Additionally, quantitative and functional analyses of the exosome cargo generated under conventional and heightened inflammation conditions are consistent with clinical observations that inflammation is linked to cancer development.

Project description:Background: Sepsis-associated encephalopathy (SAE) is a common and severe complication of sepsis. While several studies have reported the proteomic alteration in plasma, urine, heart, etc. of sepsis, few research focused on the brain tissue. This study aims at discovering the differentially abundant proteins in the brains of septic rats to identify biomarkers of SAE. Methods: The Prague-Dawley rats were randomly divided into sepsis (n = 6) or sham (n = 6) groups, and then the whole brain tissue was dissected at 24 h after surgery for further protein identification by TMT-LC–MS/MS-based proteomics. Ingenuity pathway analysis, Gene ontology knowledgebase, and STRING database are used to explore the biological significance of proteins with altered concentration. Results: Among the total of 3163 proteins identified in the brain tissue, 57 were increased while 38 were decreased in the sepsis group compared to the sham group. Bioinformatic analyses suggest that the differentially abundant proteins are highly related to cellular microtubule metabolism, energy production, nucleic acid metabolism, neurological disease, etc. Additionally, acute phase response signaling was possibly activated and PI3K/AKT signaling was suppressed during sepsis. An interaction network established by IPA revealed that Akt1, Gc-globulin, and ApoA1 were the core proteins. The increase of Gc-globulin and the decrease of Akt1 were confirmed by Western blot. Conclusions: Based on the multifunction of these proteins in several brain diseases, we first propose that Gc-globulin, ApoA1, PI3K/AKT pathway, and acute phase response proteins (hemopexin and cluster of alpha-2-macroglobulin) can potentially be diagnosis biomarkers, therapeutic targets, and prognosis indicators of SAE. These results may provide new insights into the pathologic mechanism of SAE, yet further research is required to explore the functional implications and clinical applications of the differentially abundant proteins in the brains of sepsis group.

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Dataset Information

Hepatic acute phase proteins control innate immune responses during infection by promoting myeloid derived suppressor cell function

Publications

Hepatic acute-phase proteins control innate immune responses during infection by promoting myeloid-derived suppressor cell function.

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