Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Transcriptional profiling and functional characterization of Schistosoma japonicum-stimulated Alternatively Activated Macrophages

ABSTRACT: Alternatively activated macrophages (AAMφs) play important roles in a number of Th2 driven pathologies including asthma and allergy, and a number of parasitic infections. Our studies, and those of others, investigating the pathologies associated with infection with the helminth Schistosoma japonicum implicate a role for AAMφs in fibrosis and immunomodulation.. In the present study we show that S. japonicum-secreted egg antigens are able to induce the alternative activation of macrophages as characterised by the induction of Chi3l3 and Arg1 expression. Retnla, another common marker of AAMφs, was not consistently induced in these macrophages suggesting that the specific function of these cells may differ to those induced by S. mansoni and other parasites. Closer examination of the gene expression profile and functionality of these cells identified pathways independent of Retnla expression that could be important for their immunomodulatory activity such as modulating expression of T-cell co-stimulatory molecules and chemokines. In vivo generated S. japonicum soluble egg antigen stimulated AAMφs also exhibited a reduction in their phagocytic ability likely related to the induction of IL4 and decreased expression of cell surface receptors. Additionally these macrophages exhibited reduced expression of Toll-like receptors (TLRs) and an associated reduction in responsiveness to stimulation with TLR ligands. We did not observe pathways that would suggest that AAMφs have a direct profibrotic activity. Taken together, these data describe a mechanism by which alternative activation of macrophages may be induced during S. japonicum infection and highlight the importance of the context of activation in directing AAMφ phenotype and function. The gene expression profile of Schistosoma japonicum soluble egg antigen (SEA)-stimulated macrophages was compared with that of PBS stimulated controls. Macrophages were isolated from the peritoneal cavity of BALB/c mice (n=6 per group) stimulated by intraperitoneal injection with SEA or PBS. The macrophages were pooled and RNA was extracted from these cells. Microarray analysis was performed on cRNA synthesised from total RNA derived from these macrophages. The experiment was performed twice creating two biological replicates. Fold-change (relative to the respective PBS control) reported in supplementary file linked below.

ORGANISM(S): Mus musculus

SUBMITTER: Melissa Burke

PROVIDER: E-GEOD-32621 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Lipid A (a hexaacylated 1,4 bis-phosphate) is a potent immune stimulant for TLR4/MD-2. Upon lipid A ligation, the TLR4/MD-2 complex dimerizes and initiates signal transduction. Historically, studies also suggested the existence of TLR4/MD-2-independent LPS signaling. Here we define the role of TLR4 and MD-2 in LPS signaling by using genome wide expression profiling in TLR4- and MD-2-deficient macrophages after stimulations with peptidoglycan-free LPS and synthetic E.coli lipid A. Of the 1,396 genes found significantly induced or repressed by any one of the treatments in the wildtype macrophages, none was present in the TLR4- or MD-2-deficient macrophages, confirming that the TLR4/MD-2 complex is the only receptor for endotoxin, and are both absolutely required for responses to LPS. Using a molecular genetics approach, we investigated the mechanism of TLR4/MD-2 activation by combining the known crystal structure of TLR4/MD-2 with computer modeling. We used lipid IVa, a defined lipid A mimetic to model the activation of mouse TLR4/MD2. The two phosphates on lipid A were predicted to interact extensively with the two positively charged patches mouse TLR4 according to our dimeric murine TLR4/MD-2/lipid IVa model. These two patches are composed of K263, R337, and K360 (Positive Patch 1), and K367 and R434 (Positive Patch 2). When either Positive Patch was abolished by mutagenesis into Ala, the responses to LPS and lipid A were almost abrogated. Thus, ionic interactions between the two phosphates on lipid A and the two positively charged patches on murine TLR4 appear to be essential for LPS receptor activation. The gene expression profile of macrophages from C57BL/6 and MD-2-deficient mice following either 10 ng LPS /mL, 100 ng lipid A/mL or 10 nM Pam2 stimulation for 2 hours were compared to PBS-stimulated control cells . In vitro differentiated macrophages from two individual WT and MD-2-deficient mice were cultured and stimulated with agonists separately, comparing the gene expression to PBS-stimulated control cells from the same mouse. Comparisons of PBS-stimulated WT cells to PBS-stimulated MD-2-deficient cells were performed to directly compare basal gene expression in the two genotypes.

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Transcriptional profiling and functional characterization of Schistosoma japonicum-stimulated Alternatively Activated Macrophages

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