CELLULAR RESPONSES OF IMMORTALIZED HUMAN MONOCYTES FOLLOWING EXPOSURE TO AGRICULTURAL DAIRY PARTICULATE MATTER

Abstract

Background: Agricultural particulate matter less than 10 μm in aerodynamic diameter (PM₁₀) is recognized as a contributor to respiratory and neurodegenerative diseases. Specifically, higher rates of exposure are known during agricultural practices. Still, the mechanisms linking PM exposure to airway inflammation remain incomplete or poorly defined. Lipid mediators such as prostaglandins and leukotrienes play a central role in inflammatory signaling, specifically in the respiratory system. Understanding their signals [Mo1.1]may clarify how agricultural PM contributes to both local and systemic health effects.Methods: Particulate matter was collected from inside parlor of a modern dairy farm in Fort Collins, CO, and used to expose THP-1 non-differentiated human monocytes at 1, 10, and 100 mg/mL for 6, 12, and 24 hours. Eicosanoid production and expression of key biosynthetic enzymes were assessed by ELISA and real-time PCR. RNA transcripts for eicosanoid-regulating enzymes were quantified alongside secreted lipid mediators. Viability assays established non-lethal exposure conditions appropriate for inflammatory assessment. Results: Dose- dependent increases in prostaglandin E₂ (PGE₂) of 100-200 pg/ml and to a lesser extent leukotriene E₄ (LTE₄) increased by around 25 pg/ml, but remained relatively stable. These changes were accompanied by a 10x up-regulation of cyclooxygenase-2 (COX-2) and a 2x upregulation of arachidonate 15-[JS2.1]lipoxygenase (ALOX-5), though it still was stable in its regulation by dose and times used. The results were collected while maintaining greater than 70% viability within the dose and time groups. Conclusions: This study will provide mechanistic insight into how agricultural PM activates inflammatory pathways including eicosanoid production in both immune and epithelial cells. This research will advance understanding of PM-induced airway disease, including asthma, COPD, and allergic rhinitis, while also suggesting potential for systemic effects.[