RESUMO
The immune responses of males and females to bacterial infections display differences. The mechanisms that underlie this sexual dimorphism are multifactorial. Lipopolysaccharide (LPS) contributes to the pathogenesis of endotoxaemia. We have previously demonstrated that the plasma protein beta-2 glycoprotein-1 (ß2GPI) reduces LPS-induced inflammation in male mice. In the present study using a more robust infection model of septicaemia the role of ß2GPI is examined in both male and female wild type (WT) and ß2GPI deficient (ß2GPI-/-) mice challenged with Escherichia coli (E. coli) intravenously. ß2GPI deficiency led to an increase of E. coli colony forming units (CFU) in the circulation of both male and female mice. In male ß2GPI-/- mice this was associated with a worse clinical severity score. This difference was not observed between female ß2GPI-/- and female WT mice. Male WT mice had decreased levels of total and increased levels of free thiol ß2GPI following administration of LPS or E. coli. This pattern of sexual dimorphic response was also observed in our cohort of humans with sepsis. These findings support a role for ß2GPI in modulating the sex-specific susceptibility to gram-negative septicaemia.