Project description:The Mrp8 and Mrp14 proteins (calprotectin) accumulate within tissues during aging and may contribute to chronic inflammation. To address this possibility, we evaluated calprotectin-deficient Mrp14-KO and wild-type (WT) mice at 5 and 24 months of age. However, there was no evidence that age-related inflammation is blunted in KO mice. Inflammation makers were in fact elevated in livers from old KO mice, and microarray analysis revealed more consistent elevation of genes specifically expressed by B-cells and T-cells. Adipose-specific genes, however, were less consistently elevated in aged KO mice, suggesting an anti-steatosis effect of Mrp8/14 deficiency. Consistent with this, genes decreased by the anti-steatosis agent SRT1720 were decreased in old KO compared to old WT mice. Expression of lipid metabolism genes was altered in KO mice at 5 months of age, along with genes associated with development, biosynthesis and immunity. These early-age effects of Mrp8/14 deficiency, in the absence of any external stressor, were unexpected. Taken together, our findings demonstrate a pro-steatosis rather than pro-inflammatory role of calprotectin within the aging liver. This appears to reflect a developmental-metabolic phenotype of Mrp14-KO mice that is manifest at a young age in the absence of pro-inflammatory stimuli.
Project description:The alarmins myeloid-related protein (MRP) 8 and MRP14 are the dominant cytoplasmic proteins in phagocytes. After release by activated phagocytes extracellular MRP8/MRP14 complexes promote inflammation in many diseases, including infections, allergies, autoimmune diseases, rheumatoid arthritis or inflammatory bowel disease. As receptors for the pro-inflammatory effects of human MRP8, the active component of the MRP8/MRP14-complex, Toll-like receptor (TLR) 4 and the multi-ligand receptor of advanced glycation end products (RAGE) are controversial discussed. Using a comparative bioinformatics analysis between genome-wide response patterns of monocytes to MRP8, endotoxin and different cytokines we demonstrated a dominant role of TLR4 during MRP8-mediated phagocyte activation. The relevance of this signaling pathway could be confirmed in independent cell models for TLR4 and RAGE dependent signaling in mouse and man. In addition to well-known proinflammatory functions of MRP8 our systems biology approach unraveled a novel anti-apoptotic effect of MRP8 on monocytes which was confirmed in independent functional experiments. Our data define the dominance of the TLR4-MRP8 axis in activation of human phagocytes which represents a novel attractive target for modulation of overwhelming innate immune responses. We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process. Human blood monocyte stimulated with various stimuli (control, MRP8, LPS, TNF, IL1) were selected for RNA extraction and hybridization on Affymetrix microarrays.
Project description:The alarmins myeloid-related protein (MRP) 8 and MRP14 are the dominant cytoplasmic proteins in phagocytes. After release by activated phagocytes extracellular MRP8/MRP14 complexes promote inflammation in many diseases, including infections, allergies, autoimmune diseases, rheumatoid arthritis or inflammatory bowel disease. As receptors for the pro-inflammatory effects of human MRP8, the active component of the MRP8/MRP14-complex, Toll-like receptor (TLR) 4 and the multi-ligand receptor of advanced glycation end products (RAGE) are controversial discussed. Using a comparative bioinformatics analysis between genome-wide response patterns of monocytes to MRP8, endotoxin and different cytokines we demonstrated a dominant role of TLR4 during MRP8-mediated phagocyte activation. The relevance of this signaling pathway could be confirmed in independent cell models for TLR4 and RAGE dependent signaling in mouse and man. In addition to well-known proinflammatory functions of MRP8 our systems biology approach unraveled a novel anti-apoptotic effect of MRP8 on monocytes which was confirmed in independent functional experiments. Our data define the dominance of the TLR4-MRP8 axis in activation of human phagocytes which represents a novel attractive target for modulation of overwhelming innate immune responses. We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process.
Project description:Liver steatosis is a common cause of chronic liver disease. To investigate the molecular basis of hepatic steatosis, low-density lipoprotein receptor-deficient (LDLR -/-) mice were fed Western diet (WD, 42% of calories from fat) for 5, 14, or 42 days and evaluated against mice fed a normal laboratory diet. Histological analyses revealed that steatosis was detected as early as 14 days of WD feeding. Bulk RNA sequencing demonstrated that WD feeding altered liver transcriptomes related to inflammation and cell adhesion consistent with the progression of liver steatosis. Previous studies determined that hepatocyte-specific deficiency of angiotensinogen (AGT), the unique substrate of the renin-angiotensin system (RAS), alleviates WD-induced hepatic steatosis in mice. However, the effects of hepatic AGT deficiency were not mimicked by pharmacological inhibition of the RAS, and the molecular mechanisms by which AGT deficiency protects against WD-induced steatosis is unknown. Therefore, liver transcriptomes were compared between hepatocyte-specific AGT deficient mice (hepAGT -/-) and their wild-type littermates (hepAGT +/+) after 14 days of WD feeding. Gene ontology analyses showed that upregulated genes in hepAGT -/- mice were enriched for metabolic processes and downregulated genes were enriched for cell division pathways. The integration analysis of the two RNA sequencing data identified 5 key genes, Smpd3, Dtl, Cdc6, Mki67, and Top2a, which were primarily associated with cell division processes in hepAGT +/+ mice and were suppressed in hepAGT -/- mice. In conclusion, hepatic AGT deficiency downregulated genes related to cell division during the progression of liver steatosis.
Project description:Hyporesponsiveness by phagocytes, a well-known phenomenon in sepsis, is frequently induced by low-dose endotoxin-stimulation of Toll-like-receptor-4 (TLR4) but can also be found under sterile inflammatory conditions. We now demonstrate that the endogenous alarmins myeloid-related protein (MRP) 8 and MRP14 induce phagocyte hyporesponsiveness via chromatin modifications in a TLR4-dependent manner resulting in enhanced survival during murine septic shock. Also during sterile inflammation, polytrauma and burn patients present with initially high MRP serum concentrations identifying these proteins as obvious candidates for triggering secondary hyporesponsiveness in these patients. Interestingly, increased peripartal MRP concentrations prime human neonatal phagocytes for hyporesponsiveness, which was confirmed in murine neonatal endotoxinemia in wildtype and MRP14 -/- mice. Using a comparative bioinformatics analysis between genome-wide response patterns of MRP- and LPS- tolerized monocytes we demonstrated no difference in global gene expression between samples pretreated with either MRP8-MRP14 or LPS. Our data indicate that alarmin-triggered phagocyte tolerance represents a novel regulatory mechanism for the susceptibility of neonates to systemic infections and during sterile inflammation. Human blood monocytes prestimulated with MRP8-MRP14 or LPS and afterwards activated with LPS were selected for RNA extraction and hybridization on Illumina microarrays.
Project description:Age-related inflammation or ‘inflammaging’ is a key mechanism that increases disease burden and may control lifespan. How adipose tissue macrophages (ATMs) control inflammaging is not well understood in part because the molecular identities of niche-specific ATMs are incompletely known. Using intravascular labeling to exclude circulating myeloid cells and subsequent single-cell sequencing with orthogonal validation, we define the diversity and alterations in niche resident ATMs through lifespan. Aging led to depletion of vessel-associated macrophages (VAMs), expansion of lipid-associated macrophages (LAMs), and emergence of a unique subset of CD38+ age-associated macrophages (AAMs) in visceral white adipose tissue (VAT). Interestingly, CD169+CD11c- ATMs are enriched in a subpopulation of nerve-associated macrophages (NAMs) that declines with age. Depletion of CD169+ NAMs in aged mice increases inflammaging and impairs lipolysis suggesting that they are necessary for preventing catecholamine resistance in VAT. These findings reveal specialized ATMs control adipose homeostasis and link inflammation to tissue dysfunction during aging.
Project description:Examining the effect of CMPF treatment in the livers of mice. This study examines both the prevention and reversal of steatosis. We used arrays to determine the pathways through which CMPF prevents and reverses steatosis