Antifibrotic action of medicinal mushrooms Ganoderma lucidum and Polyporus umbellatus in MDCK and CRFK cells.

Chronic kidney disease (CKD) is a significant cause of morbidity and mortality in dogs and cats, characterized by progressive renal dysfunction and interstitial fibrosis. Renal fibrosis is primarily driven by epithelial-mesenchymal transition (EMT) mediated by transforming growth factor-β1 (TGF-β1). Due to limited antifibrotic therapies, increasing attention is focused on natural bioactive compounds, including medicinal mushrooms such as Ganoderma lucidum (GL) and Polyporus umbellatus (PU). However, their nephroprotective effects in companion animals remain poorly characterized. Here, we examined the effects of GL and PU extracts on cell viability and EMT-related gene expression in canine (MDCK) and feline (CRFK) renal cells using MTT and NRU assays, with EMT assessed by mRNA expression of α-SMA, TIMP1, Col1a, and FN1 under basal and TGF-β1-induced conditions. The chemical profiles of the extracts were characterized by ultra-high-resolution mass spectrometry. Both extracts were non-cytotoxic up to 5 mg/mL and increased viability in MDCK and CRFK cells (p < 0.05). Under basal conditions, GL modestly reduced EMT marker expression, whereas PU showed limited effects. Under TGF-β1 stimulation, both extracts significantly suppressed EMT-related genes; however, the combined GL + PU treatment had a stronger inhibitory effect on α-SMA, TIMP1, Col1a, and FN1 expression than either extract alone (p < 0.01), indicating additive antifibrotic activity. In conclusion, GL and PU extracts effectively suppress TGF-β1-induced EMT renal cells without cytotoxicity, and combined treatment is more effective than each extract alone. These in vitro findings suggest that medicinal mushroom extracts are promising nephroprotective and antifibrotic candidates that require further validation in vivo in companion animals.