title: High salt induces anti-inflammatory MΦ2-like phenotype in peripheral macrophages.
abstract: Macrophages play a critical role in inflammation and antigen-presentation. Abnormal macrophage function has been attributed in autoimmune diseases and cancer progression. Recent evidence suggests that high salt tissue micro-environment causes changes in macrophage activation. In our current report, we studied the role of extracellular sodium chloride on phenotype changes in peripheral circulating monocyte/macrophages collected from healthy donors. High salt (0.2 M NaCl vs basal 0.1 M NaCl) treatment resulted in a decrease in MΦ1 macrophage phenotype (CD11b+CD14highCD16low) from 77.4±6.2% (0.1 M) to 29.3±5.7% (0.2 M, p<0.05), while there was an increase in MΦ2 macrophage phenotype (CD11b+CD14lowCD16high) from 17.2±5.9% (0.1 M) to 67.4±9.4% (0.2 M, p<0.05). ELISA-based cytokine analysis demonstrated that high salt treatment induced decreased expression of in the MΦ1 phenotype specific pro-inflammatory cytokine, TNFα (3.3 fold), IL-12 (2.3 fold), CCL-10 (2 fold) and CCL-5 (3.8 fold), but conversely induced an enhanced expression MΦ2-like phenotype specific anti-inflammatory cytokine, IL-10, TGFβ, CCL-17 (3.7 fold) and CCR-2 (4.3 fold). Further high salt treatment significantly decreased phagocytic efficiency of macrophages and inducible nitric oxide synthetase expression. Taken together, these data suggest that high salt extracellular environment induces an anti-inflammatory MΦ2-like macrophage phenotype with poor phagocytic and potentially reduced antigen presentation capacity commonly found in tumor microenvironment.
authors.affiliation: Department of Medicine, Mercy Hospital, St Louis, MO.
authors.forename: Suneetha
authors.initials: S
authors.lastname: Amara
authors.affiliation: Department of Chemistry, Tennessee State University; Nashville, TN.
authors.forename: Margaret
authors.initials: M
authors.lastname: Whalen
authors.affiliation: Department of Biological Sciences, Tennessee State University; Nashville, TN.
authors.forename: Venkataswarup
authors.initials: V
authors.lastname: Tiriveedhi
keywords: Arg-1; Cancer; Cytokine; Inflammation; Macrophage; iNOS