Carnosine Supplementation Mitigates the Deleterious Effects of Particulate Matter Exposure in Mice

Background-Exposure to fine airborne particulate matter (PM2.5) induces quantitative and qualitative defects in bone marrow- derived endothelial progenitor cells of mice, and similar outcomes in humans may contribute to vascular dysfunction and the cardiovascular morbidity and mortality associated with PM2.5 exposure. Nevertheless, mechanisms underlying the pervasive effects of PM2.5 are unclear and effective interventional strategies to mitigate against PM2.5 toxicity are lacking. Furthermore, whether PM2.5 exposure affects other types of bone marrow stem cells leading to additional hematological or immunological dysfunction is not clear. Methods and Results-Mice given normal drinking water or that supplemented with carnosine, a naturally occurring, nucleophilic di-peptide that binds reactive aldehydes, were exposed to filtered air or concentrated ambient particles. Mice drinking normal water and exposed to concentrated ambient particles demonstrated a depletion of bone marrow hematopoietic stem cells but no change in mesenchymal stem cells. However, HSC depletion was significantly attenuated when the mice were placed on drinking water containing carnosine. Carnosine supplementation also increased the levels of carnosine-propanal conjugates in the urine of CAPs-exposed mice and prevented the concentrated ambient particles-induced dysfunction of endothelial progenitor cells as assessed by in vitro and in vivo assays. Conclusions-These results suggest that exposure to PM2.5 has pervasive effects on different bone marrow stem cell populations and that PM2.5 -induced hematopoietic stem cells depletion, endothelial progenitor cell dysfunction, and defects in vascular repair can be mitigated by excess carnosine. Carnosine supplementation may be a viable approach for preventing PM2.5-induced immune dysfunction and cardiovascular injury in humans.