Resolvin D1 prevents TNF-α-mediated disruption of salivary epithelial formation

Abstract

Sjögren's syndrome is a chronic autoimmune disorder characterized by inflammation of salivary glands resulting in impaired secretory function. Our present studies indicate that chronic exposure of salivary epithelium to TNF-α and/or IFN-γ alters tight junction integrity, leading to secretory dysfunction. Resolvins of the D-series (RvDs) are endogenous lipid mediators derived from DHA that regulate excessive inflammatory responses leading to resolution and tissue homeostasis. In this study, we addressed the hypothesis that activation of the RvD1 receptor ALX/FPR2 in salivary epithelium prevents and/or resolves the TNF-α-mediated disruption of acinar organization and enhances monolayer formation. Our results indicate that 1) the RvD1 receptor ALX/FPR2 is present in fresh, isolated cells from mouse salivary glands and in cell lines of salivary origin; and 2) the agonist RvD1 (100 ng/ml) abolished tight junction and cytoskeletal disruption caused by TNF-α and enhanced cell migration and polarity in salivary epithelium. These effects were blocked by the ALX/FPR2 antagonist butyloxycarbonyl-Phe-Leu-Phe-Leu-Phe. The ALX/FPR2 receptor signals via modulation of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways since, in our study, blocking PI3K activation with LY294002, a potent and selective PI3K inhibitor, prevented RvD1-induced cell migration. Furthermore, Akt gene silencing with the corresponding siRNA almost completely blocked the ability of Par-C10 cells to migrate. Our findings suggest that RvD1 receptor activation promotes resolution of inflammation and tissue repair in salivary epithelium, which may have relevance in the restoration of salivary gland dysfunction associated with Sjögren's syndrome.

Resolvin D1 Stimulates Alveolar Fluid Clearance through Alveolar Epithelial Sodium Channel, Na,K-ATPase via ALX/cAMP/PI3K Pathway in Lipopolysaccharide-Induced Acute Lung Injury

“…The PI3K has been identified as integral for regulation of ENaC-mediated AFC by insulin (32). Previous studies showed that RvD1 treatment in Par-Cro cells prevents TNF-a-mediated disruption of salivary epithelia formation and enhances cell migration and cell polarity via PI3K signaling (60). This study revealed that LY294002, a PI3K inhibitor, markedly attenuated RvD1-induced cAMP concentration and expressions of ENaC a in primary ATII cells stimulated with LPS, FIGURE 11.…”

ALX/FPR2 receptor for RvD1 is expressed and functional in salivary glands

“…Preincubation of cells with RvD1 abolished tight junction and cytoskeletal disruption caused by TNF-␣ (30). Furthermore, RvD1 enhanced lumen formation and cell polarity in Par-C10 cells cultured under two-and threedimensional conditions through Akt signaling (30). These results indicate that RvD1 has the potential to improve salivary epithelial integrity in vitro and in vivo.…”

“…These mediators exhibit anti-inflammatory and proresolving actions to block cell damage and enhance tissue repair after injury or infection (9,16,18,26). Previously, we showed that resolvin D1 (RvD1) prevents inflammatory responses and enhances tissue integrity in the rat parotid cell line Par-C10 (30). Preincubation of cells with RvD1 abolished tight junction and cytoskeletal disruption caused by TNF-␣ (30).…”

Expression of Resolvin D1 Biosynthetic Pathways in Salivary Epithelium

“…signaling in several tissues, including corneal, renal, and salivary epithelium (Hassan and Gronert, 2009;Li et al, 2010;Odusanwo et al, 2012). The enzymes PLA 2 and LOX have been widely studied in many cell systems (Appendix Discussion).…”