Clostridium perfringens α-toxin impairs erythropoiesis by inhibition of erythroid differentiation

Clostridium perfringens alpha-toxin induces hemolysis of erythrocytes from various species, but it has not been elucidated whether the toxin affects erythropoiesis. In this study, we treated bone marrow cells (BMCs) from mice with purified alpha-toxin and found that TER119(+) erythroblasts were greatly decreased by the treatment. A variant alpha-toxin defective in enzymatic activities, phospholipase C and sphingomyelinase, had no effect on the population of erythroblasts, demonstrating that the decrease in erythroblasts was dependent of its enzymatic activities. alpha-Toxin reduced the CD71(+) TER119(+) and CD71(-) TER119(+) cell populations but not the CD71(+) TER119(-) cell population. In addition, alpha-toxin decreased the number of colony-forming unit erythroid colonies but not burst-forming unit erythroid colonies, indicating that alpha-toxin preferentially reduced mature erythroid cells compared with immature cells. alpha-Toxin slightly increased annexinV(+) cells in TER119(+) cells. Additionally, simultaneous treatment of BMCs with alpha-toxin and erythropoietin greatly attenuated the reduction of TER119(+) erythroblasts by alpha-toxin. Furthermore, hemin-induced differentiation of human K562 erythroleukemia cells was impaired by alpha-toxin, whereas the treatment exhibited no apparent cytotoxicity. These results suggested that alpha-toxin mainly inhibited erythroid differentiation. Together, our results provide new insights into the biological activities of alpha-toxin, which might be important to understand the pathogenesis of C. perfringens infection.