2021 MSUFCU Best Biology poster for the Lyman Briggs Research Showcase
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Omega-3-Fatty Acid Docosahexaenoic Acid (DHA) Suppresses Silica-triggered Cathepsin B release, Cell Death, and Proinflammatory Cytokine/Chemokine Secretion in Alveolar Macrophage-like MPI cells
Adrianna Kirby, 3rd year |
Abstract:
Respiratory exposure to crystalline silica (cSiO2), an occupational toxicant, leads to the development of pulmonary inflammation, which can contribute to the autoimmune disease lupus. Alveolar macrophages (AM) phagocytose cSiO2 which induces a cycle of phagolysosomal permeabilization, inflammasome activation, proinflammatory cytokine/chemokine release, and cell death. These actions generate initial unresolved pulmonary inflammation and subsequent systemic autoimmunity in genetically susceptible individuals.
Utilizing Max Planck Institute (MPI) cells, a novel AM model, we: 1) evaluate cSiO2’s effects on cathepsin release, cytokine/chemokine secretion and cell death with and without LPS priming and 2) determine how DHA intervention influences cSiO2-induced aforementioned effects. MPI cells were i) preincubated with 25 μM DHA or Vehicle (Veh) for 24h, ii) primed with LPS (20 ng/mL) or Veh for 2h, and iii) exposed to cSiO2 (12.5 μg/cm2) for 1.5 or 4h. ELISAs, Cathepsin B activity assays, and LDH cell death assays were performed. Following LPS priming, cSiO2 elicited robust IL-1a, IL-6, TNF-a, MCP-1 release, and inflammasome activation as reflected by IL-1β release compared to time-matched controls. DHA significantly suppressed IL-1a, IL-1β, IL-6, TNF-a, and MCP-1 release by cSiO2 at 4h and BAFF at 1.5h. At 1.5h DHA suppressed cSiO2-induced cathepsin release regardless of LPS priming. cSiO2 induced cell death within 1.5h of exposure, peaking at 4h regardless of LPS priming suggesting inflammasome-independent and -dependent cell death while DHA inhibited LDH release for all treatment groups. Taken together, these findings suggest DHA at a physiologically relevant concentration was capable of inhibiting cathepsin release, cytokine/chemokine secretion, and cell death.
