Pinobanksin ameliorated DSS-induced acute colitis mainly through modulation of SLC7A11/glutathione-mediated intestinal epithelial ferroptosis.

Inhibition of ferroptosis in intestinal epithelial cells serves as an attractive target for the development of therapeutic strategies for colitis. Pinobanksin, one of the main flavonoids derived from propolis, possesses significant anti-inflammatory effects and inhibits the cell death of several cell lines. Here, we evaluated whether pinobanksin influenced colitis by modulation of epithelial ferroptosis. Mice treated with 2.5% DSS dissolved in sterile distilled water were established for an acute colitis model. The mitochondrial morphology, colonic iron level, lipid peroxidation products MDA/4-HNE, and lipid reactive oxygen species levels were measured to assess ferroptosis in epithelial cells. RNA-seq and functional analyses were performed to reveal key genes mediating pinobanksin-exerted modulation of ferroptosis. We found that pinobanksin, at different doses, induced significant anti-colitis effects and inhibited the elevated ferroptosis in colonic epithelial cells isolated from DSS-treated mice largely by activating GPX4 (negative regulator of ferroptosis). Furthermore, RNA-seq assays indicated that pinobanksin significantly increased the cystine transporter SLC7A11 in colonic tissues from mice with colitis. Depletion of SLC7A11 largely blocked pinobanksin-induced promotion of cystine uptake/glutathione biosynthesis and suppression of ferroptosis in epithelial cells from mice with colitis or IEC-6 cells pretreated with RSL3. Altogether, pinobanksin alleviated DSS-induced colitis largely by inhibition of ferroptosis in epithelial cells. Activation of SLC7A11 by pinobanksin resulted in the promotion of cystine uptake and enhancement of glutathione biosynthesis. This work will provide novel guidance for the clinical use of pinobanksin to treat colitis through inhibition of epithelial ferroptosis.

Fortunellin-Induced Modulation of Phosphatase and Tensin Homolog by MicroRNA-374a Decreases Inflammation and Maintains Intestinal Barrier Function in Colitis.

Activation of phosphatase and tensin homolog (PTEN) is known to induce cell apoptosis. MicroRNA-374a (miR-374a), which can suppress PTEN expression, has been found abnormally expressed in inflammatory bowel disease (IBD). Fortunellin is a citrus flavonoid that is a potential anti-inflammation agent in inflammatory diseases. The present study investigated the effects and mechanisms underlying fortunellin-induced inhibition of PTEN in IBD. Colitis was established in rats by the intracolonic administration of 2,4,6-trinitrobenzene sulfonic acid to mimic human ulcerative colitis, which is the main type of IBD. miR-374a expression was measured by quantitative real-time polymerase chain reaction, and the regulation of PTEN by miR-374a was evaluated by dual luciferase reporter assay. Western blotting was used to measure the corresponding protein expression. Fortunellin ameliorated colitis symptoms, including excessive inflammation and oxidative stress. Fortunellin decreased epithelial cell apoptosis through inhibiting PTEN expression in colitis. Fortunellin-induced downregulation of PTEN could be counteracted by miR-374a depletion. Moreover, knockdown of miR-374a in vivo partly inhibited the effects of fortunellin on rat colitis. In conclusion, PTEN inhibition contributes to the amelioration effects of fortunellin on colitis. It was confirmed that fortunellin targets miR-374a, which is a negative regulator of PTEN. This study provides novel insights into the pathological mechanisms and treatment alternatives of colitis.

A general frame of theory on genetic load.

Genetic load expresses the loss in mean fitness of a population because of the genetic variability present. The quantitative discussion of various genetic loads is provided with important meaning for research into evolution of species on realistic level. The past theory on genetic load starts off with equilibrium of population to investigate the evolution of species on realistic level. However, the evolution is a displacement on equilibrium of population. This is just made up of a contradiction between theory and praxis. We branch out the past theory on genetic load, and give out a general theoretic frame describing the various genetic loads. By the use of this theoretic frame the genetic loads in an equilibrium population can be represented, and the genetic loads in a non-equilibrium population and their change can also be simulated. Thus this theoretic frame overcomes the shortcoming of past theory on genetic loads, which can't describe non-equilibrium population and conflicts with praxis of biological evolution sometimes, and offers a sort of credible simulation methods for research into evolution of species.