Cell volume restriction by mercury chloride reduces M1-like inflammatory response of bone marrow-derived macrophages

Dysregulation of macrophages in the pro-inflammatory (M1) and anti-inflammatory (M2) sub-phenotypes is a crucial element in several inflammation-related diseases and injuries. We investigated the role of aquaporin (AQP) in macrophage polarization using AQP pan-inhibitor mercury chloride (HgCl(2)). Lipopolysaccharides (LPSs) induced the expression of AQP-1 and AQP-9 which increased the cell size of bone marrow-derived macrophages. The inhibition of AQPs by HgCl(2) abolished cell size changes and significantly suppressed M1 polarization. HgCl(2) significantly reduced the activation of the nuclear factor kappa B (NF-κB) and p38 mitogen-activated protein kinase (MAPK) pathways and inhibited the production of IL-1β. HgCl(2) attenuated LPS-induced activation of mitochondria and reactive oxygen species production and autophagy was promoted by HgCl(2). The increase in the light chain three II/light chain three I ratio and the reduction in PTEN-induced kinase one expression suggests the recycling of damaged mitochondria and the restoration of mitochondrial activity by HgCl(2). In summary, the present study demonstrates a possible mechanism of the AQP inhibitor HgCl(2) in macrophage M1 polarization through the restriction of cell volume change, suppression of the p38 MAPK/NFκB pathway, and promotion of autophagy.