Effects of a soil Mycobacterium-derived lipid 10(Z)-hexadecenoic acid, on murine bone marrow-derived dendritic cells: a mechanistic analysis
Year: 2023
Type: dissertation
Abstract: Inflammatory disorders and stress-related psychiatric disorders in which chronic low-grade inflammation may be a risk factor are a prevalent issue worldwide. This rise could be in part due to compromised immunoregulation. Immunoregulation, defined as a balance of effector T cells and regulatory T cells (Treg), is stimulated by microbial signals, which include organisms that are found in soil and other natural environments that humans are exposed to. Immunoregulation is thought to be dysregulated in modern urbanized societies, due to humans having less exposure to microbes termed “Old Friends”. The “Old Friends” hypothesis proposes that people living in modernized societies have reduced exposure to diverse microbial communities present in the environment that promote immunoregulation. ‘Old Friends” microbes are thought to have their immunoregulatory effect in part by inducing the differentiation of naive dendritic cells (DCs) into regulatory DCs, which are thought to be master regulators of the immune system. An “Old Friend”, Mycobacterium vaccae NCTC 11659 is a soil-derived mycobacterium with anti- inflammatory and immunoregulatory effects. Some of these effects may be mediated by a lipid, 10(Z)-hexadecenoic acid (10(Z)-HDA), isolated from M. vaccae NCTC 11659. Studies have shown that 10(Z)-HDA acts as an agonist at the host peroxisome proliferator-activated receptor (PPAR)-alpha (PPARα) to induce anti-inflammatory effects in murine peritoneal macrophages. To determine if 10(Z)-HDA acts via PPARα to induce anti-inflammatory effects in dendritic cells, we conducted studies using 10(Z)-HDA and the PPARα antagonist GW6471 and assessed inflammatory biomarkers in murine bone marrow-derived dendritic cells (BMDCs) with or without subsequent immune challenge using lipopolysaccharide (LPS). Murine BMDCs were treated with two doses of GW6471 (0.24 μg/ml, 2.4 μ–/ml) - or vehicle (1.5% DMSO), followed by 10(Z)-HDA at 250 μg/ml, or vehicle (13% DMSO, with a final well concentration of 0.5%). Twenty-four hours later, an immune challenge with LPS (Escherichia coli 0111:B4; 250 ng/ml) or vehicle was added. Cells were harvested 24 hours later, and quantification of gene expression was assessed using real time reverse transcription polymerase chain reaction (real time RT- PCR). After treatment with 2.4 μg/ml GW6471, relative to a vehicle-treated control within condition, a significant decrease in interleukin 6 (Il6) expression following 10(Z)-HDA and LPS treatment was observed, suggesting that Il6 expression in murine BMDCs is controlled in part by PPARα. These results further our understanding of the mechanism by which 10(Z)-HDA has its effects and understanding of host mycobacteria interactions.
Author: Elizabeth Alexandra Holmes Hunter
Language: English
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7112321355