Prdx6-induced inhibition of ferroptosis in epithelial cells contributes to liquiritin-exerted alleviation of colitis.

Inhibition of ferroptosis in intestinal epithelial cells ameliorates clinical symptoms and improves endoscopic presentations in inflammatory bowel disease (IBD). Licorice is used worldwide in food and medicine fields. Liquiritin, a flavonoid component in licorice, is an effective substance used as an anti-inflammatory, antioxidant food that has been shown to improve chemically induced colitis. Herein we evaluated the therapeutic effects of liquiritin on colitis and determined whether liquiritin could affect colitis by modulating ferroptosis in epithelial cells. A colitis model was induced in mice by oral administration with 2.5% DSS dissolved in drinking water. The results showed that liquiritin significantly alleviated symptoms, suppressed intestinal inflammation and restored the epithelial barrier function in the colitis mouse model. Liquiritin supplementation upregulated colonic ferritin expression, increased the storage of cellular iron, reduced the cellular iron level and further inhibited ferroptosis in epithelial cells from the colitis model. Pharmacological stimulation of ferroptosis largely blocked liquiritin-induced alleviation of colitis. Peroxiredoxin-6 (Prdx6) expression was significantly decreased in the DSS group, which was reversed by liquiritin treatment. Genetic or pharmacological silencing of Prdx6 largely reversed liquiritin-induced modulation of the ferritin/iron level and ferroptosis in epithelial cells. Molecular docking results showed that liquiritin could bind to Prdx6 through the hydrogen bond interaction with amino acid residues Thr208, Val206 and Pro203. In conclusion, liquiritin treatment largely alleviated DSS induced colitis by inhibiting ferroptosis in epithelial cells. Liquiritin negatively regulated ferroptosis in epithelial cells in colitis by activating Prdx6, increasing the expression of ferritin and subsequently reducing the cellular iron level.

Therapeutic material basis and underling mechanisms of Shaoyao Decoction-exerted alleviation effects of colitis based on GPX4-regulated ferroptosis in epithelial cells.

BACKGROUND: Shaoyao Decoction (SYD) is a canonical herbal medicine prescription formulated by Liu Wan-Su in AD 1186. SYD has been widely used to treat inflammatory bowel disease by clearing heat and damp, removing stasis toxin in the intestine; however, the precise mechanisms and therapeutic material basis remain largely unclear. In the present study, we measured the effects of SYD on colitis symptom, epithelial barrier function, epithelial ferroptosis, colonic protein and mRNA expression of glutathione peroxidase 4 (GPX4) in colitis model, and determined whether SYD restored barrier loss in colitis by modulation of GPX4-regulated ferroptosis pathway. METHODS: Colitis was established by infusion with 1 mL 2,4,6-trinitrobenzene sulfonic acid (TNBS) dissolved in ethanol (40% v/v) in rats at a 125 mg/kg dose. Ferroptosis in epithelial cells was determined by flow cytometer. GPX4 promoter-firefly luciferase fusion construct was transfected to Caco-2 cell to determine GPX4 transcription. MS analysis was used to identified ingredients in SYD. RESULTS: Different doses of SYD significantly alleviated colitis, decreased ferroptosis in epithelial cells, knockout of GPX4 significantly reversed SYD-induced alleviation effects on colitis, restoration of epithelial barrier function, and epithelial ferroptosis. Wogonoside, wogonin, palmatine, paeoniflorin and liquiritin were identified as active ingredients of SYD-exerted alleviation effects of colitis based on GPX4 agonistic transcription. CONCLUSION: SYD alleviated chemically induced colitis by activation of GPX4, inhibition of ferroptosis in epithelial cells and further restoration of barrier function. Wogonoside, wogonin, palmatine, paeoniflorin and liquiritin were identified as the key therapeutic material basis of SYD-exerted anti-colitis effects. The findings provide a scientific basis for the therapeutic effect of SYD on colitis.

Triptolide, a Chinese herbal extract, enhances drug sensitivity of resistant myeloid leukemia cell lines through downregulation of HIF-1α and Nrf2.

AIM: To explore whether triptolide (TPL) can enhance drug sensitivity of resistant myeloid leukemia cell lines through downregulation of HIF-1α and Nrf2. MATERIALS & METHODS: HL60/A and K562/G cells were subjected to different treatments and thereafter an methyl thiazole tetrazolium bromide assay, flow cytometry, western blot and real-time PCR were used to determine IC50, apoptotic status and expression of Nrf2, HIF-1α and their target genes. RESULTS: Doxorubicin- or imatinib-induced apoptosis was enhanced when anticancer agents were used in combination with TPL. When combined with TPL, both doxorubicin and imatinib downregulate Nrf2 and HIF-1α expression at protein and mRNA levels. Genes downstream of Nrf2, for example, NQO1, GSR and HO-1, as well as target genes of HIF-1α, for example, BNIP3, VEGF and CAIX are also downregulated at the mRNA level. CONCLUSION: TPL is able to enhance drug sensitivity of resistant myeloid leukemia cell lines through downregulation of HIF-1α and Nrf2.