Influence of TRPV1 and TRPV4 cation channel agonists on the expression of activation markers by peripheral blood mononuclear cells

Abstract

Introduction. Transient receptor potential channels TRPV1 and TRPV4 are expressed in leukocytes and may contribute to the pathogenesis of chronic obstructive pulmonary disease; however, data on their functional roles in immune cells remain limited and contradictory. Aim. To determine changes in the expression of surface activation markers on human peripheral blood lymphocytes and monocytes in response to pharmacological stimulation of TRPV1 and TRPV4. Materials and methods. Peripheral blood mononuclear cells were isolated from eight apparently healthy volunteers (39.9 ± 2.00 years; 50% male) by Ficoll density-gradient centrifugation. The effects of the TRPV1 agonist capsaicin and the TRPV4 agonist RN1747 on cell metabolic activity were assessed using the CCK-8 assay. The expression of the activation markers CD63, CD25, CD69, CD11b, and HLA-DR on lymphocytes and monocytes was evaluated by flow cytometry after 24 h of incubation with 10 μM capsaicin or 10 μM RN1747. Expression levels were reported as the percentage of positive cells or as normalized median fluorescence intensity (nMFI). Statistical significance was assessed using p values adjusted by the Benjamini–Hochberg method (padj). Results. Capsaicin and RN1747, each at 10 μM, did not reduce the metabolic activity of mononuclear cells. Capsaicin significantly decreased the proportions of monocytes positive for CD63 (79.19 [66.89; 86.55]% vs. 65.94 [56.45; 79.52]%, p adj = 0.03), CD25 (12.81 [5.83; 18.47]% vs. 9.33 [5.51; 16.47]%, p adj = 0.04), CD11b (95.06 [94.20; 96.92]% vs. 93.78 [91.89; 94.74]%, p adj = 0.03), and CD69 (36.54 [34.42; 40.63]% vs. 29.65 [23.07; 33.94]%, p adj = 0.03). Significant reductions in nMFI were observed for CD63 (3.39 [3.04; 3.86] vs. 2.86 [2.44; 3.17], p adj = 0.01), CD25 (1.39 [1.30; 1.49] vs. 1.29 [1.18; 1.43], p adj = 0.01), HLA-DR (36.87 [20.30; 47.17] vs. 29.63 [16.80; 33.43], p adj = 0.01), and CD69 (2.11 [1.95; 2.25] vs. 1.91 [1.74; 2.07], p adj = 0.01). In lymphocytes, capsaicin reduced the proportions of CD63-positive cells (4.66 [4.00; 6.90]% vs. 3.84 [3.27; 5.87]%, p adj = 0.04) and CD69-positive cells (5.01 [3.27; 9.42]% vs. 4.81 [2.67; 8.04]%, p adj = 0.04). In monocytes, RN1747 reduced the nMFI of CD63 (3.39 [3.04; 3.86] vs. 2.78 [2.64; 3.01], p adj = 0.04) and CD69 (2.11 [1.95; 2.25] vs. 1.88 [1.75; 2.00], p adj = 0.04), but had no significant effect on lymphocytes. Conclusion. Monocytes demonstrated broader phenotypic sensitivity to pharmacological activation of TRPV channels, particularly TRPV1, in comparison with lymphocytes. The combined decrease in the studied markers may indicate the development of a hyporeactive monocyte phenotype with potentially reduced secretory, adhesive, migratory, phagocytic, and antigen-presenting functions.