Variation of sexual dimorphism and asymmetry in disease expression of inflammatory arthritis among laboratory mouse models with different genomic backgrounds

Sex difference has shown in the arthritis diseases in human population and animal models. We investigate how the sex and symmetry vary among mouse models with different genomic backgrounds. Disease data of sex and limbs accumulated in the past more than two decades from four unique populations of murine arthritis models were analyzed. They are (1) interleukin-1 receptor antagonist (IL-1ra) deficient mice under Balb/c background (Balb/c KO); (2) Mice with collagen II induced arthritis under DBA/1 background; (3) Mice with collagen II induced arthritis under C57BL/6 (B6) background and (4) A F2 generation population created by Balb/c KO X DBA/1 KO. Our data shows that there is a great variation in sexual dimorphism for arthritis incidence and severity of arthritis in mice harboring specific genetic modifications. For a F2 population, the incidence of arthritis was 57.1% in female mice and 75.6% in male mice. There was a difference in severity related to sex in two populations: B6.DR1/ B6.DR4 (P