Modulation of Neointimal Hyperplasia Severity in Rats by Commensal Microbial Transfer

Neointimal hyperplasia is a major contributor to restenosis after arterial interventions. The genetic and environmental mechanisms underlying the variable propensity for neointimal hyperplasia between individuals are not well understood. One possible modulator could be commensal gut microbes. To address whether microbes mediate neointimal hyperplasia, we cohoused genetically different rats (Lewis [LE] and Sprague-Dawley [SD]) which harbor different commensal microbes and compared neointimal hyperplasia 2 weeks after carotid angioplasty in the cohoused and non-cohoused cohorts. Cohousing is a means of microbial transfer between cage inhabitants. We observed that differences in neointimal hyperplasia between non-cohoused LE and SD rats (median intima+media [I+M] area 0.12 mm2 LE vs. 0.26 mm2 SD, Pu003c.0001;Mann-Whitney) were mitigated when rats are cohoused for 1 month (Figure 1A), suggesting an environmental effect that outweighs the genetic influence. Specifically, I+M area decreased by 23% in SD rats that w...