ABSTRACT
Persistent chronic inflammation and fibrosis product accumulation aggravate tubulointerstitial fibrosis (TIF), leading to the progression of chronic kidney disease. The aim of this study was designed to investigate the effect of protocatechualdehyde (PCA), a natural phenolic acid compound isolated from Salvia miltiorrhiza, on the unilateral ureteral obstruction (UUO)-induced fibrosis and inflammation and to elucidate the underlying mechanism in primary renal tubular epithelial cells (TECs). Results from the histology suggested that the moderate to severe deteriorations of renal dysfunction and the pathological changes in UUO could be relieved by PCA treatment. Mechanistic studies revealed that the effect of PCA was associated with the downregulation of Smad3 and NF-κB driven fibrosis and inflammation respectively. It is worth noting that PCA could inhibit the aberrant expression of inflammation cytokines such as iNOS, MCP-1, TNF-α in UUO, and IL-1ß-treated TECs. In addition, PCA also suppressed the expression of Smad3-dependent long noncoding RNA (lncRNA), 9884. Importantly, when overexpressing of lncRNA9884 in TECs by transfection of pcDNA3.1-lncRNA9884 plasmid, it revealed significant reversal of protein expression levels as that observed with only PCA, suggesting that PCA inhibits inflammation by mediating lncRNA9884/MCP-1 signaling pathway. Collectively, the current study establishes a foundational basis for PCA in future treatment of obstructive nephropathy.