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Angiotensin‐II Induced Hypertensive Renal Injury is Mediated through HMGB1‐TLR4 Signaling in Rat Tubulo‐Epithelial Cells
Author(s) -
Nair Anand,
Ebenezer Philip,
Francis Joseph
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.811.10
Subject(s) - hmgb1 , angiotensin ii , tlr4 , inflammation , proinflammatory cytokine , gene silencing , kidney , signal transduction , chemistry , renin–angiotensin system , losartan , microbiology and biotechnology , endocrinology , medicine , pharmacology , biology , receptor , biochemistry , blood pressure , gene
Angiotensin II is a vaso‐constrictive peptide that regulates blood pressure homeostasis. Even though the inflammatory effects of AngII in renal pathophysiology have been studied, there still exists a paucity of data with regard to the mechanism of action of AngII‐mediated kidney injury. The objective of this study was to elucidate the mechanistic role of HMGB1‐TLR4 signaling in AngII‐induced inflammation in the kidney. Rat tubular epithelial cells (NRK52E) were treated with AngII over a preset time‐course. In another set of experiments, HMGB1 was neutralized and TLR4 was knocked down using small interfering RNA targeting TLR4. Cell extracts were subjected to RT‐PCR, immunoblotting, flow cytometry, ELISA. AngII induced inflammation in NRK52E cells increased gene and protein expression of TLR4, HMGB1 and proinflammatory cytokines. Pretreatment with Losartan attenuated the AngII‐induced expression of TLR4 and inflammatory molecules. TLR4 silencing was used to elucidate the specific role played by TLR4 in AngII induced inflammation. TLR4siRNA treatment in these cells significantly decreased the AngII induced inflammatory effect. Consistent observations were made when the cells were pretreated with anti‐HMGB1 before an AngII insult. Downstream activation of NFκB and rate of generation of ROS was also decreased on gene silencing of TLR4 and exposure to anti‐HMGB1. These results indicate a key role for HMGB1‐TLR4 signaling in ANGII‐mediated inflammation in the renal epithelial cells. Our data also reveal that AngII‐induced effects could be alleviated by HMGB1‐TLR4 inhibition, suggesting this pathway as an important therapeutic target for hypertensive renal dysfunctions.