Cellular and molecular mechanisms of alpha lipoic acid’s protective effects against diclofenac-induced hepatorenal toxicity

TL;DR

This study shows that alpha lipoic acid protects against liver and kidney damage caused by diclofenac through antioxidant, anti-inflammatory, and Nrf2-related mechanisms.

Contribution

The study identifies the Nrf2 signaling pathway as a key mechanism in ALA's hepatorenal protection against diclofenac toxicity.

Findings

Alpha lipoic acid reduced oxidative stress and inflammation in liver and kidney tissues.

ALA improved liver and kidney histology and reduced caspase-3 expression, indicating anti-apoptotic effects.

Nrf2 pathway genes were upregulated by ALA, suggesting a molecular mechanism for its protective effects.

Abstract

The cellular and molecular pathways of α-lipoic acid’s (ALA’s) protective effect were assessed against diclofenac (DIC) hepatorenal injury in vivo and against a pro-inflammatory stimulus in vitro.

The injury was induced in 28 adult male Wistar rats weighing 130–160 g by a single intraperitoneal injection of DIC (50 mg per kg body weight (b.w.)) on the fifth day. Seven positive control rats had received no hepatorenally protective compounds. Oral 100 mg/kg b.w. doses of silymarin (SLY) were given to seven animals, 50 mg/kg b.w. doses of ALA to seven more and 100 mg/kg b.w. doses of it to another seven for five days before DIC insult. Seven negative control rats received only distilled water instead of protective compound and in the injection. The anti-inflammatory effect of ALA was also assayed in murine RAW264.7 macrophage cells.

In the cells, ALA was antioxidant and anti-inflammatory in a dose-dependent manner, reducing nitric oxide (NO) and reactive oxygen species generation with half maximal concentrations of 7.8 and 6.25 μg/mL, respectively. Both ALA doses and SLY protected the hepatorenal tissues and improved kidney and hepatic functions compared to the organs of the positive control group. Additionally, ALA reduced oxidative stress biomarker levels in hepatic and renal tissues compared to the positive control rats. It also improved liver and kidney histology, where hepatic lesions were fewer, and protected renal architecture. Immunohistochemical analysis showed ALA to reduce caspase-3 expression, supporting its hepatorenal anti-apoptotic effect. Alpha lipoic acid markedly upregulated the hepatorenal messenger RNA expressions of nuclear factor erythroid 2-related factor 2 (Nrf2), haem oxygenase-1 and nicotinamide adenine (phosphate) reduced form : quinone oxidoreductase 1, suggesting that the Nrf2 signalling pathway was enhanced.

These findings suggested potential therapeutic benefits for ALA in mitigating DIC-induced hepatorenal toxicity through its anti-inflammatory, antioxidant and Nrf2-mediating effects. Future investigations are warranted to explore the synergistic interactions and multiomics mechanisms.

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