Cavalcante, Marcelo Borges

Abstract Cellular senescence contributes to age-related disorders including physical dysfunction, disabilities, and mortality caused by tissue inflammation and damage. Senescent cells accumulate in multiple tissues with aging and at etiological sites of multiple chronic disorders. The senolytic drug combination, Dasatinib plus Quercetin (D+Q), is known to reduce senescent cell abundance in aged mice. However, the effects of long-term D+Q treatment on intestinal senescent cell and inflammatory burden and microbiome composition in aged mice remain unknown. Here, we examine the effect of D+Q on senescence (p16Ink4a and p21Cip1) and inflammation (Cxcl1, Il1β, Il6, Mcp1, and Tnfα) markers in small (ileum) and large (caecum and colon) intestine in aged mice (n = 10) compared to age-matched placebo-treated mice (n = 10). Additionally, we examine microbial composition along the intestinal tract in these mice. D+Q-treated mice show significantly lower senescent cell (p16 and p21 expression) and inflammatory (Cxcl1, Il1β, Il6, Mcp1, and Tnfα expression) burden in small and large intestine compared with control mice. Further, we find specific microbial signatures in ileal, cecal, colonic, and fecal regions that are distinctly modulated by D+Q, with modulation being most prominent in small intestine. Further analyses reveal specific correlation of senescence and inflammation markers with specific microbial signatures. Together, these data demonstrate that the senolytic treatment reduces intestinal senescence and inflammation while altering specific microbiota signatures and suggest that the optimized senolytic regimens might improve health via reducing intestinal senescence, inflammation, and microbial dysbiosis in older subjects.

Cellular senescence represents one of the major risk factors for chronic liver disease and contributes to morbidity, mortality, and increased healthcare spending. A relevant strategy for understanding the role of senescent cells in liver pathogenesis is to use genetic or pharmacological strategies to eliminate senescent cells. The combination of the senolytic drugs, Dasatinib and Quercetin (D+Q), effectively reduces senescent cell burden in multiple tissues, extending both healthspan and lifespan in mice, and alliviating obesity and age‐associated hepatic steatosis. The aim of this study was to investigate effects of D+Q treatment on livers of young and old female mice. A total of 40 mice, 20 young females (3‐months) and 20 old females (18‐months), was divided into 4 groups: Young (Y) mice treated with either D+Q or placebo and old (O) mice treated with D+Q or placebo. The treatment was performed for 3 consecutive days every 2 weeks over 10 weeks. Comparative analysis of hepatic miRNAs indicated that D+Q treatment significantly decreased levels of senescence‐specific miR‐126 expression in livers of old mice treated with D+Q compared to vehicle‐treated old mice (p=0.025), As expected, there was no effect of D+Q treatment in young animals. Analysis of miR‐126 target genes indicated that PI3K gene expression was significantly increased in response to D+Q treatment (p=0.003). Additionally, Akt1 and mTOR mRNA levels were increased in D+Q‐treated mice (p=0.008 and p=0.02, respectively). In summary, our data suggest that the mechanism of PI3K signaling pathway activation upon elimination of senescent cells by treatment with D+Q is mediated through downregulation of senescence‐specific miR‐126. Support or Funding Information This work is supported by National Institutes of Health (NIH) (R56AG061414, R15AG059190 and R03AG059846)