Project description:There is evidence that microglia interact with infiltrating Th1 and Th17 cells and this interaction results in mutual activation. However, the potential of a distinct cytokine milieu generated by these effector T cell subsets to activate microglia is poorly understood. In this study, we tested the ability of factors secreted by Th1 and Th17 cells to induce microglial activation. Interestingly, we found that only Th1-associated factors had the potential to activate microglia while the Th17-associated factors as well as direct contact of Th17 cells with microglia only had a minimal effect. Further Th1-derived factors triggered a proinflammatory M1-type gene expression profile in microglia Microglia harvested from mixed glial cultures were treated with supernatants from Th1- or Th17 cultures. Microglia cultured in medium was used as controls. At 16h post treatment RNA was isolated from the microglia and probed on Agilent´s murine 4x44k microarrays. RNA isolated from four independent experiments were used for the gene expression profiling. Microglia, Th1, Th17
Project description:There is evidence that microglia interact with infiltrating Th1 and Th17 cells and this interaction results in mutual activation. However, the potential of a distinct cytokine milieu generated by these effector T cell subsets to activate microglia is poorly understood. In this study, we tested the ability of factors secreted by Th1 and Th17 cells to induce microglial activation. Interestingly, we found that only Th1-associated factors had the potential to activate microglia while the Th17-associated factors as well as direct contact of Th17 cells with microglia only had a minimal effect. Further Th1-derived factors triggered a proinflammatory M1-type gene expression profile in microglia
Project description:Autoreactive T cells that infiltrate into the central nervous system (CNS) are believed to have a significant role in mediating the pathology of neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis and multiple sclerosis. Their interaction with microglia and astrocytes in the CNS is crucial for the regulation of the neuroinflammatory process. Our previous work demonstrated that effectors secreted by Th1 and Th17 cells have different capacities to influence the phenotype and function of the glial cells. We have shown that Th1 effectors altered the phenotype and function of both microglia and astrocytes whereas Th17 effectors induced direct effects only on astrocytes but not on microglia. Here we investigated if effector molecules associated with IFN-g producing Th1 cells induced different gene expression profiles in microglia and astrocytes. We performed a microarray analysis of RNA isolated from microglia and astrocytes treated with medium and Th1 culture supernatants and compared the gene expression data. By using the criteria of 2-fold change and a false discovery rate of 0.01 (corrected p-value < 0.01), we demonstrated that a total of 2106 and 1594 genes were differentially regulated microglia and astrocytes respectively in response to Th1-derived factors. We observed that Th1 associated effectors induce distinct transcriptional changes in microglia and astrocytes in addition to commonly regulated transcripts. These distinct transcriptional changes regulate distinct physiological functions and this knowledge can help in better understanding of T cell mediated neuropathologies.
Project description:CD4+ T cells differentiate into phenotypically distinct T-helper cells upon antigenic stimulation. Regulation of plasticity between these CD4+ T-cell lineages is critical for immune homeostasis and prevention of autoimmune diseases. However, the factors that regulate lineage stability are largely unknown. Here we investigate a role for retinoic acid (RA) in the regulation of lineage stability using T helper 1 (Th1) cells, traditionally considered the most phenotypically stable Th subset. We found that RA, through its receptor RARa, sustains stable expression of Th1 lineage specifying genes as well as repressing genes that instruct Th17 cell fate. RA signaling is essential for limiting Th1 cell conversion into Th17 effectors and for preventing pathogenic Th17 responses in vivo. Our studies identify RA-RARa as a key component of the regulatory network governing Th1 cell fate and define a new paradigm for the development of pathogenic Th17 cells. These findings have important implications for autoimmune diseases in which dysregulated Th1-Th17 responses are observed. Identification of RARa binding in wild-type Th1 cells and mapping of enhancers using chromatin IP against p300, H3k4me1, H3k4me3, and H3k27ac in wild-type and dnRara Th1 cells.
Project description:Engrams are considered to be substrates for memory storage, and the functional dysregulation of the engrams leads to cognition impairment.However, the cellular basis for these maladaptive changes lead to the forgetting of memories remains unclear. Here we found that the expression of autophagy protein 7 (Atg7) mRNA was dramatically upregulated in aged DG engrams, and led to the forgetting of contextual fear memory and the activation of surrounding microglia.To determine mechanism by which autophagy in DG engrams activates the surrounding microglia, mice were co-injected AAV-RAM-Cre either with AAV-Dio-Atg7-Flag or AAV-Dio- EYFP in dorsal dentate gyrus to overexpress ATG7 in the DG memory engrams. Microglia were separated using magnetic-activated cell sorting and subjected to RNA-Seq in dorsal hippocampus .Bioinformatics analysis shown overexpression of Atg7 in dorsal DG memory engrams caused an increase in the expression of Tlr2 in the surrounding microglia.Depletion of Toll-like receptor 2/4 (TLR2/4) in DG microglia prohibited excessive microglial activation and synapse elimination induced by the overexpression of ATG7 in DG engrams, and thus prevented forgetting. Furthermore, the expression of Rac1, a Rho-GTPases which regulates active forgetting in both fly and mice, was upregulated in aged engrams. Optogentic activation of Rac1 in DG engrams promoted the autophagy of the engrams, the activation of microglia, and the forgetting of fear memory. Invention of the Atg7 expression and microglia activation attenuated forgetting induced by activation of Rac1 in DG engrams. Together, our findings revealed autophagy-dependent synapse elimination of DG engrams by microglia as a novel forgetting mechanism.