Early hematopoietic injury triggered by benzene characterized with inhibition of erythrocyte differentiation involving the mollicutes_RF39-derived citrulline.

Benzene poisoning is a common adverse blood outcome in occupational workers, manifested by hematopoietic dysfunction. However, the specific phenotype and its mechanisms of early hematopoietic toxicity caused by benzene remain unclear. After 15 days of exposure, the WBC levels were not significantly altered in benzene-exposed mice. However, the level of red blood cells (RBC) showed a significant decrease, and it was significantly and negatively correlated with urinary S-phenylmercapturic acid (SPMA). Notably, 5 mg/kg benzene exposure significantly inhibited the renewal capacity and the number of colony formation of hematopoietic stem progenitor cells in mice, especially erythrocyte differentiation. These results suggested that the early hematopoietic toxicity phenotype caused by benzene was dominated by inhibition of erythroid differentiation rather than WBC-related inflammation. To further understand the underlying mechanisms of benzene-induced early hematopoietic toxicity, 16 S rRNA sequencing and plasma metabolites analysis were conducted to investigate the impact of benzene exposure for 15 days on microbial composition and metabolic profile of mice. We found that short-term benzene exposure induced disturbances in gut microbiota and metabolism. The relative abundance of Mollicutes_RF39 at order levels was significantly reduced in benzene-exposed mice and was strongly correlated with hematopoietic indicators and urinary benzene markers. Interestingly, Mollicutes_RF39 might disturb the levels of eight metabolites, whereas Citrulline was highly linked to Mollicutes_RF39 (r = 0.862, P = 0.000). Consequently, Mollicutes_RF39-derived Citrulline might be the key regulator of early hematopoietic injury induced by benzene exposure. These findings promote the understanding of early hematotoxicity phenotypes and provide new perspectives on the underlying mechanisms of benzene-induced hematotoxicity.