Invasive
bacterial infections remain a major cause of human morbidity. Group B streptococcus (GBS) are Gram-positive bacteria that cause invasive
infections in humans. Here, we show that
factor XIIIA-deficient (FXIIIA-deficient) female mice exhibited significantly increased susceptibility to GBS
infections. Additionally, female WT mice had increased levels of FXIIIA and were more resistant to GBS
infection compared with isogenic male mice. We observed that administration of exogenous FXIIIA to male mice increased host resistance to GBS
infection. Conversely, administration of a FXIIIA
transglutaminase inhibitor to female mice decreased host resistance to GBS
infection. Interestingly, male gonadectomized mice exhibited decreased sensitivity to GBS
infection, suggesting a role for gonadal
androgens in host susceptibility. FXIIIA promoted GBS entrapment within
fibrin clots by crosslinking
fibronectin with
ScpB, a
fibronectin-binding GBS
surface protein. Thus,
ScpB-deficient GBS exhibited decreased entrapment within
fibrin clots in vitro and increased dissemination during systemic
infections. Finally, using mice in which FXIIIA expression was depleted in mast cells, we observed that mast cell-derived FXIIIA contributes to host defense against GBS
infection. Our studies provide insights into the effects of sexual dimorphism and mast cells on FXIIIA expression and its interactions with GBS adhesins that mediate bacterial dissemination and pathogenesis.