#5165 STING CONTRIBUTES TO LPS-INDUCED TUBULAR INFLAMMATION BY ACTIVATING IRE1/XBP1 PATHWAY IN ACUTE KIDNEY INJURY

Abstract

Abstract Background and Aims Innate immunity and inflammation were recognized as the key factors for the progression of acute kidney injury (AKI) induced by lipopolysaccharide (LPS). Stimulator of interferon genes (STING) has emerged as a critical component of innate immune and inflammatory responses. This study aimed to explore the role of STING in LPS-induced tubular inflammation in AKI. Method 1. The AKI mice models were induced by intraperitoneal injection of LPS. Mice were randomly divided into CTL group, LPS 24 h group and LPS 48 h group: (1) STING protein expression in tubules was detected by IHC staining; (2) STING protein expression in kidney cortices was detected by WB. 2. The tubule-specific STING knockout (STING-cKO) mice were generated. Then WT mice and STING-cKO mice were randomly divided into WT group, WT+LPS group, STING-cKO group and STING-cKO+LPS group: (1) Blood samples and urine samples were collected for Scr, BUN and ACR measurement; (2) Tubular pathological changes were detected by PAS staining; (3) Inflammatory cell infiltration in kidney cortices was detected by IHC and IF staining; (4) Pro-inflammatory cytokines’ mRNA level in kidney cortices was detected by QPCR; (5) IRE1, XBP1, IL-1β and IL-18 protein expression in kidney cortices was detected by WB. 3. HK2 cells were randomly divided into CTL group, si-STING (STING siRNA) group, LPS group, LPS+si-STING group, Ad-IRE1 (IRE1 overexpression plasmid) group, si-STING+ Ad-IRE1 group, LPS+ Ad-IRE1 group and LPS+ si-STING+ Ad-IRE1 group: (1) Pro-inflammatory cytokines’ mRNA level was detected by QPCR; (2) IL-1β, IL-18 protein expression was detected by WB. Results 1. STING was activated in tubules from LPS-induced AKI mice. 2. STING-cKO significantly suppressed LPS-induced renal dysfunction, tubular pathological changes, tubular inflammation and IRE1/XBP1 pathway activation. 3.IRE1 overexpression significantly promoted LPS-activated HK2 cells’ inflammation, even though STING was silenced. Conclusion STING contributes to LPS-induced tubular inflammation by activating IRE1/XBP1 pathway. Targeting STING may be a promising therapeutic strategy for preventing septic AKI.