Key Points

IGF-binding protein 7 (IGFBP7) expression was elevated in kidney and liver tissues of mice subjected to chronic cadmium exposure.IGFBP7 deficiency protected against cadmium-induced hepatorenal dysfunction and fibrosis.Inhibition of the IGFBP7/α-enolase/H3K18la axis may be a potential therapeutic intervention for cadmium-induced hepatorenal fibrosis.

Background

Chronic cadmium exposure can induce the onset and progression of hepatorenal fibrosis; however, its molecular basis is unclear. IGF-binding protein 7 (IGFBP7) is not only a biomarker of AKI but also plays a functional role in promoting kidney injury and inflammation. Abnormal repair of AKI causes kidney fibrosis and CKD. IGFBP7 has also been reported as a more sensitive biomarker for liver fibrosis. However, its role in hepatorenal fibrosis requires further investigation.

Methods

IGFBP7 global and conditional knockout mice were used to determine the role of IGFBP7 in cadmium-induced hepatorenal fibrosis. Then, liquid chromatography–mass spectrometry, truncated mutants, coimmunoprecipitation, and microscale thermophoresis were used to unravel the downstream mechanisms.

Results

IGFBP7 expression was significantly elevated in kidney and liver tissues of mice subjected to chronic cadmium exposure. IGFBP7 deficiency attenuated cadmium-induced hepatorenal dysfunction and fibrosis, whereas restoration of IGFBP7 expression in IGFBP7-deficient mice reproduced hepatorenal fibrosis. Mechanistically, IGFBP7 interacted with α-enolase (ENO1) and inhibited its ubiquitination and degradation. Upregulated ENO1 further promoted glucose metabolic reprogramming and lactate accumulation. Conversely, lactate accumulation enhanced IGFBP7 transcription and expression through histone H3K18 lactylation. Importantly, therapy targeting IGFBP7 significantly ameliorated cadmium-induced hepatorenal fibrosis.

Conclusions

IGFBP7 promoted cadmium-induced hepatorenal fibrosis by enhancing ENO1-driven abnormal glycolysis and lactate accumulation.