ARACHIDONIC ACID ENHANCES MITOPHAGY AND DECREASES INFLAMMATORY RESPONSE IN PRIMARY MACROPHAGES

Abstract

Macrophages are actively involved in recognizing, capturing, and destroying pathogens, as well as removing cellular debris. The most important role of macrophages is to initiate and regulate the inflammatory response: they synthesize and secrete a wide range of proinflammatory cytokines that activate other cells of the immune system and promote the development of inflammation. The functional state of macrophages directly depends on the work of mitochondria - not only as energy sources, but also as key participants in signaling pathways associated with the production of reactive oxygen species and regulation of the inflammasome. Their functional state depends on mitochondria, which are not only energy producers but also regulators of signaling pathways, including reactive oxygen species generation and inflammasome activation. Mitochondrial dysfunction can lead to excessive macrophage activation and chronic inflammation, typical of diseases like atherosclerosis and metabolic disorders. Damaged mitochondria release components such as mtDNA and cardiolipin, potentially triggering autoimmune responses. To prevent this, cells utilize mitophagy, a selective autophagy process that removes dysfunctional mitochondria via the lysosomal pathway. Polyunsaturated fatty acids are known to influence inflammation and mitochondrial function, including mitophagy. Arachidonic acid, a precursor of prostaglandins and leukotrienes, modulates immune responses, but its role in mitophagy remains unclear. The aim of this study was to investigate whether arachidonic acid affects mitophagy and the proinflammatory response of human macrophages. Primary monocytes were isolated from whole blood of healthy donors and differentiated into macrophages over 5 days. Cells were treated with 20 μM arachidonic acid for 24 hours, followed by 1 μg/ml LPS stimulation for another 24 hours. Cytokine secretion (TNF, IL6, IL8, CCL2) was measured by ELISA. Mitophagy was assessed using confocal microscopy by evaluating colocalization of mitochondrial and lysosomal dyes. The results showed that arachidonic acid enhanced mitophagy and reduced secretion of TNF, IL6, and CCL2 in response to LPS. These findings suggest that activation of mitophagy may contribute to the anti-inflammatory effects of arachidonic acid in macrophages.