The gender difference in alcohol levels is due mainly to a smaller gastric metabolism in females (because of a significantly lesser activity of chi-ADH), rather than to differences in gastric emptying or in hepatic oxidation of ethanol. The concentration-dependency of these effects may explain earlier discrepancies. The combined pharmacokinetic differences may increase the vulnerability of women to the effects of ethanol.
Background
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Interleukin (IL)-12 exerts a potent proinflammatory effect by stimulating T-helper (Th) 1 responses. This effect is believed to be mediated primarily through the activation of STAT4 and subsequent production of interferon (IFN)-γ.
Methods and Results
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We examined the role of IL-12 receptor (IL-12R) signaling in the development of murine experimental autoimmune myocarditis (EAM) induced by cardiac myosin immunization. Both IL-12Rβ1–deficient mice and STAT4-deficient mice were resistant to the induction of myocarditis. Treatment with exogenous IL-12 exacerbated disease. We questioned whether IFN-γ is required for the disease-promoting activity of IL-12. On the contrary, we found that IFN-γ suppresses EAM. Lack of IFN-γ due to either depletion with an antibody or a genetic deficiency exacerbated myocarditis. Spleens from IFN-γ–deficient mice immunized with cardiac myosin showed increased cellularity; greater numbers of CD3+, CD4+, CD8+, and IL-2–producing cells; and heightened ability to produce cytokines on stimulation in vitro. Treatment of mice with recombinant IFN-γ suppressed the development of myocarditis.
Conclusions
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IL-12
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IL-12R/STAT4 signaling promotes the development of EAM. In contrast, IFN-γ plays a protective role. The disease-limiting effects of IFN-γ might be explained by its ability to control the expansion of activated T lymphocytes.
Myocarditis is a principal cause of heart disease among young adults and is often a precursor of heart failure due to dilated cardiomyopathy. We show here that complement is critical for the induction of experimental autoimmune myocarditis and that it acts through complement receptor type 1 (CR1) and type 2 (CR2). We also found a subset of CD44(hi)CD62L(lo) T cells that expresses CR1 and CR2 and propose that both receptors are involved in the expression of B and T cell activation markers, T cell proliferation and cytokine production. These findings provide a mechanism by which activated complement, a key product of the innate immune response, modulates the induction of an autoimmune disease.
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