Browsing by Subject "Adaptive Immunity"
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Item Long-Term T Cell Responses in the Ischemic Brain(2019-11-14) Selvaraj, Uma Maheswari; Niederkorn, Jerry Y.; Stüve, Olaf; Farrar, J. David; Stowe, Ann; Goldberg, Mark P.Stroke is a debilitating and devastating disorder with significant annual mortality and morbidity rates worldwide. Following ischemic injury, blood-brain barrier integrity is disrupted and multiple inflammatory cascades are initiated both in the central nervous system and in the peripheral immune system. These early inflammatory responses result in the recruitment of systemic immune cells into the brain parenchyma. T lymphocytes, part of the adaptive arm of the immune response, are present bordering the infarct region within days after stroke. Accumulation of these cells in the early inflammatory phase peaks 3 to 4 days after stroke injury. However, T cells persists as late as 7 weeks post-stroke and it is unclear if they are beneficial or detrimental to functional recovery in this chronic phase post-stroke. We found significant numbers of CD4 T cells and CD8 T cells in the brain parenchyma long-term post-stroke. These long-term CD8 T cells were mainly present in the injured tissue area and potentially function through IFN-g secretion. We further determined that the long-term post-stroke CD8 T cells affected inflammation and functional recovery post-stroke. CD8 T cell-depleted mice demonstrated better recovery in the rotarod behavior test and had fewer immune cells recruited to the brain parenchyma post-stroke. We also observed the presence of CNS-specific T cells in the post-stroke spleens and cervical lymph nodes. Taken together, these data reveal a role for CD8 T cells in the chronic phase post-stroke that can be therapeutically targeted. Furthermore, long-term post-stroke immune cells in the brain parenchyma regulate chronic inflammatory responses and functional recovery after stroke.Item Regulation of Accessibility of the Variable Gene Segments of the Mouse Immunoglobulin Kappa Light Chain Gene Locus(2005-08-11) Brekke, Katherine Meyers; Garrard, WilliamUnderstanding the development of the expression of antibody heavy and light chain molecules is required to fully explain the adaptive immune response. This involves understanding the mechanisms underlying the selection of individual Vκ genes for V-J joining. It has been assumed that this selection involves alterations in the chromatin structure surrounding Vκ genes. Therefore, the focus of my work has centered on understanding the factors influencing the selection of a particular Vκ gene as well as the accompanying alterations in chromatin structure. I have assembled the complete nucleotide sequence of the 3.2 Mb Mus musculus Igκ gene locus and mapped all of the functional and pseudo-Vκ genes onto the sequence. I have also determined the patterns of potential transcription factor binding sites surrounding these Vκ genes. These analyses revealed statistically significant patterns of transcription factor motifs that are clustered either upstream of the transcription start site, in the intronic region, or downstream of the recombination signal sequence (RSS). The conservation of these sites has been tied to the presence of DNase I hypersensitive sites at the pre-B cell stage of development. These hypersensitive sites appear just prior to the V-J joining step and disappear after the Igκ locus has completed the rearrangement process. These sites are present at or near the promoter of the particular Vκ gene and are sometimes present near the RSS as well. I also looked for the presence of transcripts from the promoters of the Vκ genes that had HSP and HSRSS. I found that the presence of transcripts and the presence of HS was uncoupled. There were instances where both HS and transcripts were present, neither was present, or only one phenomenon was observed. This led me to conclude that these events were separable. The presence of HSRSS as well as the corresponding binding sites for transcription factors in the downstream region, suggests a model for generating accessibility of Igκ V genes for V-J joining.Item Voluntary Exercise Alters Adaptive Immunity Prior to Injury(2013-01-22) McPartlin, Angelica; Stowe, Anne M.; Poinsatte, Katherine; Mouti, Mariam; Ireland, Sarah J.; Li, MinOBJECTIVE: Exercise provides a neuroprotective role in the setting of cerebral infarct. However, the exact mechanism for this protection is unclear. This study established an exercise preconditioning protocol to test the hypothesis that exercise mediates protection from stroke by altering the immune profile prior to injury to reduce inflammation post-infarct. MATERIALS/METHODS: In our first trial, a three week exercise preconditioning protocol was established using nine C57 mice that endogenously expressed green fluorescent protein (GFP) under the PLP promoter. This biomarker was used to identify oligodendrocyte precursor cells (OPC) to qualify their relationship with voluntary exercise. Exercise activity was recorded and tissues were collected for histological and serological analysis. Analysis of histological sections acquired through Nanozoomer imaging was performed using an unbiased quantification (Stereo Investigator). Ten Swiss Webster (SW) mice with no endogenous fluorescence were used in the subsequent trial. Following sacrifice of the SW mice, samples of the spleen and peripheral blood were collected and analyzed by flow cytometry and microarray was used to analyze resident B cell expression (IPA software). Standard ELISA analysis of peripheral blood was also used for all trials. Significance was determined using t-test or ANOVA. RESULTS: Voluntary exercise in PLP-EGFP mice correlated with a trend increase in OPCs as well as a trend increase in cortical angiogenesis (p=0.06). However, voluntary exercise did not increase hippocampal neuron counts. Voluntary exercise in SW mice showed decreases in percent and raw number of splenic neutrophils and CD8+ T cells (both p<0.01), with a concomitant increase in B cell representation (p<0.05). Peripheral blood samples demonstrated a decrease in percent CD4+ T cells (p<0.01) and decrease in CCL2 (p<0.05) and VEGF (p<0.01) protein. Microarray showed a significant upregulation of 1844 genes and significant downregulation of 1333 genes in the resident splenic B cells of SW exercise mice over the sedentary controls. CONCLUSION: Three weeks of voluntary exercise in mice results in a change in the immune profile prior to an injury occurring. Downregulation of neutrophils, cytotoxic T cells, and CCL2 suggest that this alteration in immunity is anti-inflammatory. Microarray analysis of isolated B cells showed an upregulation of genes associated with lymphocyte maturation and differentiation, with simultaneous downregulation of genes responsible for apoptosis and B cell death. Further studies will determine the significance of these immune adaptations and their mechanistic role in decreased deficits following neurovascular injury.