Project description:Classically activated (M1) macrophages protect from infection but can cause inflammatory disease and tissue damage while alternatively activated (M2) macrophages reduce inflammation and promote tissue repair. Modulation of macrophage phenotype may be therapeutically beneficial and requires further understanding of the molecular programs that control macrophage differentiation. A potential mechanism by which macrophages differentiate may be through microRNA (miRNA), which bind to messenger RNA and post-transcriptionally modify gene expression, cell phenotype and function. The inflammation-associated miRNA, miR-155, was rapidly up-regulated over 100-fold in M1, but not M2, macrophages. Inflammatory M1 genes and proteins iNOS, IL-1b and TNF-a were reduced up to 72% in miR-155 knockout mouse macrophages, but miR-155 deficiency did not affect expression of genes associated with M2 macrophages (e.g., Arginase-1). Additionally, a miR-155 oligonucleotide inhibitor efficiently suppressed iNOS and TNF-a gene expression in wild-type M1 macrophages. Comparative transcriptional profiling of unactivated (M0) and M1 macrophages derived from wild-type and miR-155 knockout (KO) mice revealed an M1 signature of approximately 1300 genes, half of which were dependent on miR-155. Real-Time PCR of independent datasets validated miR-155's contribution to induction of iNOS, IL-1b, TNF-a, IL-6 and IL-12, as well as suppression of miR-155 targets Inpp5d, Tspan14, Ptprj and Mafb. Overall, these data indicate that miR-155 plays an essential role in driving the differentiation and effector potential of inflammatory M1 macrophages. Total RNA was prepared from bone marrow-derived macrophages of miR-155 knockout mice (n=2 independent mice) treated in M0, M1 or M2 conditions (n=2 replicates per condition originating from different mice)
Project description:Classically activated (M1) macrophages protect from infection but can cause inflammatory disease and tissue damage while alternatively activated (M2) macrophages reduce inflammation and promote tissue repair. Modulation of macrophage phenotype may be therapeutically beneficial and requires further understanding of the molecular programs that control macrophage differentiation. A potential mechanism by which macrophages differentiate may be through microRNA (miRNA), which bind to messenger RNA and post-transcriptionally modify gene expression, cell phenotype and function. The inflammation-associated miRNA, miR-155, was rapidly up-regulated over 100-fold in M1, but not M2, macrophages. Inflammatory M1 genes and proteins iNOS, IL-1b and TNF-a were reduced up to 72% in miR-155 knockout mouse macrophages, but miR-155 deficiency did not affect expression of genes associated with M2 macrophages (e.g., Arginase-1). Additionally, a miR-155 oligonucleotide inhibitor efficiently suppressed iNOS and TNF-a gene expression in wild-type M1 macrophages. Comparative transcriptional profiling of unactivated (M0) and M1 macrophages derived from wild-type and miR-155 knockout (KO) mice revealed an M1 signature of approximately 1300 genes, half of which were dependent on miR-155. Real-Time PCR of independent datasets validated miR-155's contribution to induction of iNOS, IL-1b, TNF-a, IL-6 and IL-12, as well as suppression of miR-155 targets Inpp5d, Tspan14, Ptprj and Mafb. Overall, these data indicate that miR-155 plays an essential role in driving the differentiation and effector potential of inflammatory M1 macrophages.
Project description:The innate inflammatory response must be tightly regulated to ensure effective immune protection while avoiding inflammation-related pathologies. The transcription factor NF-kB is a critical mediator of the inflammatory response, and its dysregulation has been associated with immune related malignancies. We herein show that miR-155, miR-146a and NF-kB form a regulatory network that tunes the macrophage inflammatory response in mice. We show that elevated miR-155 expression potentiates NF-kB activity in miR-146a deficient mice, thus leading to an overactive acute inflammatory response and chronic inflammation. Enforced miR-155 expression overrides miR-146a-mediated repression of NF-kB activation, thus emphasizing that miR-155 plays a dominant, downstream role in promoting inflammation. We further show that miR-155 deficient macrophages exhibit a suboptimal inflammatory response when exposed to low levels of inflammatory stimuli. Importantly, we demonstrate a temporal asymmetry between miR-155 and miR-146a expression during macrophage activation, which forms a combined positive and negative feedback network on NF-kB activity. This miRNA based regulatory network enables a robust and time-limited inflammatory response essential for functional immunity.
Project description:A favourable immunotherapeutic strategy in the treatment of chronic inflammatory disease, is to dampen the pro-inflammatory macrophage response and upregulate the anti-inflammatory macrophage response. Previous studies have shown that Arginase-2 (Arg2), a mitochondrial enzyme, is a key regulator of the macrophage anti-inflammatory response with an essential role in IL-10 signalling. Here we show that IL-10 in the presence of LPS increased Arg2 expression in human macrophages and peripheral blood mononuclear cells. Target site blockers (TSBs) (locked nucleic acid antisense oligonucleotides) specifically designed to target the 3’ UTR of Arg2 messenger RNA were used to inhibit binding of specific microRNAs thus enhancing Arg2 expression. Eleven Arg2-TSBs were screened and the TSB targeting miR-155 (TSB-155) and the TSB targeting miR-3202 (TSB-3202) were found to increase Arg2 expression in human macrophages resulting in decreased gene expression and cytokine production of TNF-α and CCL2. In addition, following TSB-3202 stimulation, there were statistically significant increases in the ‘M2-like’ macrophage marker, CD206; and CD16, associated with an IL-10 response, and a decrease in the ‘M1-like’ macrophage marker, HLA-DR, indicating a shift in the macrophage phenotype. Proteomic analysis demonstrated that multiple pro-inflammatory responsive proteins including Signal Transducer and Activator of Transcription 1 (STAT-1), Toll-like receptors, Signalling Lymphocytic Activation Molecule F7 (SLAMF7) and Interferon Induced Protein with Tetratricopeptide Repeats 3 (IFIT3), were downregulated by TSB-155 and TSB-3202 while Sequestomsome-1 (SQSTM1) was increased after treatment. In silico analysis of significantly dysregulated proteins predicted that TSB-3202 supressed several upstream pro-inflammatory regulators including STAT-1 and Interferon α2 (IFNA2) while enhancing anti-inflammatory associated interleukin 1 receptor antagonist (IL1RN) and STAT-3. Proteomic data was validated by confirming increased levels of SQSTM1, decreased levels of phosphoylated-STAT-1 and STAT-1, and downregulation of Ifit3 and Slamf7 by TSB treatment. In conclusion, upregulation of Arg2 protein by TSBs inhibits several pro-inflammatory signalling proteins resulting in reduced pro-inflammatory cytokine secretion, reduced ‘M1-like’ marker expression and enhanced ‘M2-like’ macrophage marker expression. Arg2 is a promising novel therapeutic target to modulate inflammatory signalling in macrophages.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Mammalian microRNAs (miRNAs) are emerging as key regulators of the development and function of the immune system. Here, we report a strong but transient induction of miR-155 in mouse bone marrow after injection of bacterial lipopolysaccharide (LPS) correlated with granulocyte/monocyte (GM) expansion. Demonstrating the sufficiency of miR-155 to drive GM expansion, enforced expression in mouse bone marrow cells caused GM proliferation in a manner reminiscent of LPS treatment. However, the mir-155-induced GM populations displayed pathological features characteristic of myeloid neoplasia. Extending possible relevance to human disease, miR-155 was overexpressed in the bone marrow of patients with acute myeloid leukemia (AML). Furthermore, miR-155 repressed a subset of genes implicated in hematopoietic development and disease. These data implicate miR-155 as a contributor to physiological GM expansion during inflammation and to certain pathological features associated with AML, emphasizing the importance of proper miR-155 regulation in developing myeloid cells during times of inflammatory stress. Experiment Overall Design: Construct stable RAW264.7 mouse macrophage cell lines expressing mir-155 or empty vector. RNA is extracted and global gene expression analysis performed to identify mir-155 regulated mRNAs.