Urolithin a alleviates oxidative stress-induced senescence in nucleus pulposus-derived mesenchymal stem cells through SIRT1/PGC-1α pathway

BACKGROUND In degenerative intervertebral disc(IVD),an unfavorable IVD environment leads to increased senescence of nucleus pulposus(NP)-derived mesenchymal stem cells(NPMSCs)and the inability to complete the differentiation from NPMSCs to NP cells,leading to further aggravation of IVD degeneration(IDD).Urolithin A(UA)has been proven to have obvious effects in delaying cell senescence and resisting oxidative stress.AIM To explore whether UA can alleviate NPMSCs senescence and to elucidate the underlying mechanism.METHODS In vitro,we harvested NPMSCs from rat tails,and divided NPMSCs into four groups:the control group,H2O2 group,H2O2+UA group,and H2O2+UA+SR-18292 group.Senescence-associatedβ-Galactosidase(SA-β-Gal)activity,cell cycle,cell proliferation ability,and the expression of senescence-related and silent information regulator of transcription 1/PPAR gamma coactivator-1α(SIRT1/PGC-1α)pathway-related proteins and mRNA were used to evaluate the protective effects of UA.In vivo,an animal model of IDD was constructed,and Xrays,magnetic resonance imaging,and histological analysis were used to assess whether UA could alleviate IDD in vivo.RESULTS We found that H2O2 can cause NPMSCs senescence changes,such as cell cycle arrest,reduced cell proliferation ability,increased SA-β-Gal activity,and increased expression of senescence-related proteins and mRNA.After UA pretreatment,the abovementioned senescence indicators were significantly alleviated.To further demonstrate the mechanism of UA,we evaluated the mitochondrial membrane potential and the SIRT1/PGC-1αpathway that regulates mitochondrial function.UA protected mitochondrial function and delayed NPMSCs senescence by activating the SIRT1/PGC-1αpathway.In vivo,we found that UA treatment alleviated an animal model of IDD by assessing the disc height index,Pfirrmann grade and the histological score.CONCLUSION In summary,UA could activate the SIRT1/PGC-1αsignaling pathway to protect mitochondrial function and alleviate cell senescence and IDD in vivo and vitro.

Zhizhu Decoction Alleviates Intestinal Barrier Damage via Regulating SIRT1/FoxO1 Signaling Pathway in Slow Transit Constipation Model Mice

Objective:To explore the possible effects and mechanism of Zhizhu Decoction(ZZD)on the pathophysiology of slow transit constipation(STC).Methods A total of 54 C57BL/6 mice was randomly divided into the following 6 groups by a random number table,including control,STC model(model),positive control,and low-,medium-and high-doses ZZD treatment groups(5,10,20 g/kg,namely L,M-,and H-ZZD,respectively),9 mice in each group.Following 2-week treatment,intestinal transport rate(ITR)and fecal water content were determined,and blood and colon tissue samples were collected.Hematoxylin-eosin and periodic acid-Schiff staining were performed to evaluate the morphology of colon tissues and calculate the number of goblet cells.To determine intestinal permeability,serum levels of lipopolysaccharide(LPS),low-density lipoprotein(LDL)and mannose were measured using enzyme-linked immunosorbent assay(ELISA).Western blot analysis was carried out to detect the expression levels of intestinal tight junction proteins zona-occludens-1(ZO-1),claudin-1,occludin and recombinant mucin 2(MUC2).The mRNA expression levels of inflammatory cytokines including tumor necrosis factor(TNF)-α,interleukin(IL)-1β,IL-6,IL-4,IL-10 and IL-22 were determined using reverse transcription-quantitative reverse transcription reaction.Colon indexes of oxidative stress were measured by ELISA,and protein expression levels of colon silent information regulator 1/forkhead box O transcription factor 1(SIRT1/FoxO1)antioxidant signaling pathway were detected by Western blot.Results Compared with the model group,ITR and fecal moisture were significantly enhanced in STC mice in the M-ZZD and H-ZZD groups(P<0.01).Additionally,ZZD treatment notably increased the thickness of mucosal and muscular tissue,elevated the number of goblet cells in the colon of STC mice,reduced the secretion levels of LPS,LDL and mannose,and upregulated ZO-1,claudin-1,occludin and MUC2 expressions in the colon in a dose-dependent manner,compared with the model group(P<0.05 or P<0.01).In addition,ZZD significantly attenuated intestinal inflammation and oxidative stress and activated the SIRT1/FoxO1 signaling pathway(P<0.05 or P<0.01).Conclusion ZZD exhibited beneficial effects on the intestinal system of STC mice and alleviated intestinal inflammation and oxidative stress via activating SIRT1/FoxO1 antioxidant signaling pathway in the colon.