Anti-inflammatory and immunoregulatory effects of pinolenic acid in rheumatoid arthritis.

Takala, Rabaa; Ramji, Dipak P; Andrews, Robert; Zhou, You; Burston, James; Choy, Ernest

OBJECTIVES In pre-clinical studies, pinolenic acid (PNLA), an omega-6-polyunsaturated fatty acid from pine nuts has shown anti-inflammatory effects. We aimed to investigate the effect of PNLA in human cell lines and peripheral blood mononuclear cells (PBMCs) from rheumatoid arthritis (RA) patients and healthy controls (HCs). METHODS Modified Boyden chamber was used to assess chemokine-induced migration of THP-1 monocytes. Macropinocytosis was assessed using lucifer yellow and ox-LDL uptake using Dil-oxLDL in THP-1 macrophages and human monocyte-derived macrophages (HMDM). IL6, TNFα and PGE2 release by lipopolysaccharide (LPS) stimulated PBMCs from RA patients and HCs were measured by ELISA. The transcriptomic profile of PNLA treated, LPS activated PBMCs was investigated by RNA-sequencing. RESULTS PNLA reduced THP-1 cell migration by 55% (p< 0.001). Macropinocytosis and Dil-oxLDL uptake were reduced by 50% (p< 0.001) and 40% (p< 0.01) in THP-1 macrophages and 40% (p< 0.01) and 25% (p< 0.05) in HMDM, respectively. PNLA reduced IL6 and TNFα release from LPS stimulated PBMCs from RA by 60% (p< 0.001) and by 50% and 35% respectively (p< 0.01) for HCs. PNLA also reduced PGE2 levels in such PBMCs from RA patients and HCs (p< 0.0001). Differentially expressed genes included upregulated expression of pyruvate dehydrogenase kinase-4, plasminogen activator inhibitor-1, fructose bisphosphatase 1 and N-Myc downstream-regulated gene, which have potential roles in regulating immune and metabolic pathways. Pathway analysis predicted upstream activation of nuclear receptors peroxisome proliferator-activated receptors involved in anti-inflammatory processes, and inhibition of NF-κB and STAT1. CONCLUSIONS PNLA has immune-metabolic effects on monocytes and PBMC which are pathogenic in RA and atherosclerosis. Dietary PNLA supplementation may be beneficial in RA.