ABSTRACT
Acute kidney injury (AKI), characterized by aggressive inflammatory responses and destruction of renal resident cells, can cause abrupt kidney dysfunction. To date, effective therapy for AKI is lacking. In this study, we evaluated the renoprotective effect of wogonin, an herbal active compound, using a cisplatin-induced AKI mouse model. In vivo results show that wogonin substantially suppressed the increased levels of serum creatinine and blood urea nitrogen (BUN) almost to the normal level. Wogonin also attenuated tubular damage, shown by PAS staining, electron microscopy and molecular analysis of KIM-1. In addition, wogonin suppressed kidney inflammation as indicated by a >60% decrease in macrophage infiltration, a >50% reduction in inflammatory cytokine production and inhibited NF-κB activation in the injured kidney. Mechanistically, molecular docking results show that wogonin effectively inhibited RIPK1 by occupying the ATP-binding pocket of the enzyme, which is a key regulator of necroptosis. Moreover, inhibition of RIPK1, or RIPK3, reversed the protective effects of wogonin in cisplatin-treated HK2 cells, indicating wogonin works in a RIPK1/RIPK3-dependent manner. Surprisingly, wogonin enhanced the anti-proliferative effect of cisplatin on human hepatoma HepG2 cells. Thus, our findings suggest wogonin may be a renoprotective adjuvant for cisplatin-based anticancer therapy.
Subject(s)
Acute Kidney Injury/prevention & control , Antineoplastic Agents/adverse effects , Apoptosis/drug effects , Cisplatin/adverse effects , Flavanones/therapeutic use , Kidney/drug effects , Protective Agents/therapeutic use , Acute Kidney Injury/chemically induced , Acute Kidney Injury/metabolism , Acute Kidney Injury/pathology , Animals , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Anti-Inflammatory Agents, Non-Steroidal/metabolism , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Binding Sites , Biomarkers/blood , Biomarkers/metabolism , Catalytic Domain , Cell Line, Transformed , Cell Line, Tumor , Cisplatin/antagonists & inhibitors , Cisplatin/pharmacology , Flavanones/chemistry , Flavanones/metabolism , Flavanones/pharmacology , Humans , Kidney/immunology , Kidney/metabolism , Kidney/pathology , Kidney Tubules/drug effects , Kidney Tubules/immunology , Kidney Tubules/metabolism , Kidney Tubules/ultrastructure , Macrophage Activation/drug effects , Male , Mice, Inbred C57BL , Microscopy, Electron, Transmission , Molecular Docking Simulation , Protective Agents/chemistry , Protective Agents/metabolism , Protective Agents/pharmacology , RNA Interference , Receptor-Interacting Protein Serine-Threonine Kinases/antagonists & inhibitors , Receptor-Interacting Protein Serine-Threonine Kinases/chemistry , Receptor-Interacting Protein Serine-Threonine Kinases/metabolismABSTRACT
Acute kidney injury (AKI) is exacerbated in C-reactive protein transgenic mice but alleviated in Smad3 knockout mice. Here we used C-reactive protein transgenic/Smad3 wild-type and C-reactive protein transgenic/Smad3 knockout mice to investigate the signaling mechanisms by which C-reactive protein promotes AKI. Serum creatinine was elevated, and the extent of tubular epithelial cell necrosis following ischemia/reperfusion-induced AKI was greater in C-reactive protein transgenics but was blunted when Smad3 was deleted. Exacerbation of AKI in C-reactive protein transgenics was associated with increased TGF-ß/Smad3 signaling and expression of the cyclin kinase inhibitor p27, but decreased phosphorylated CDK2 and expression of cyclin E. Concomitantly, tubular epithelial cell proliferation was arrested at the G1 phase in C-reactive protein transgenics with fewer cells entering the S-phase cell cycle as evidenced by fewer bromodeoxyuridine-positive cells. In contrast, the protection from AKI in C-reactive protein transgenic/Smad3 knockout mice was associated with decreased expression of p27 and promotion of CDK2/cyclin E-dependent G1/S transition of tubular epithelial cells. In vitro studies using tubular epithelial cells showed that C-reactive protein activates Smad3 via both TGF-ß-dependent and ERK/MAPK cross talk mechanisms, Smad3 bound directly to p27, and blockade of Smad3 or the Fc receptor CD32 prevented C-reactive protein-induced p27-dependent G1 cell cycle arrest. In vivo, treatment of C-reactive protein transgenics with a Smad3 inhibitor largely improved AKI outcomes. Thus, C-reactive protein may promote AKI by impairing tubular epithelial cell regeneration via the CD32-Smad3-p27-driven inhibition of the CDK2/cyclin E complex. Targeting Smad3 may offer a new treatment approach for AKI.
