The in utero environment is an important determinant of cardiovascular disease. The increasing prevalence of maternal obesity, hypercholesterolemia, insulin resistance and diabetes during pregnancy is therefore expected to lead to a wave of cardiovascular disease in offspring, but little is known about the mechanisms of in utero programming. Although metabolic changes associated with diabetic conditions are complex, pathogenic mechanisms and therapeutical targets for three key factors, hypercholesterolemia, insulin resistance, and inflammation, can now be determined in experimental models. Maternal hypercholesterolemia and the ensuing increased oxidative stress lead to increased fatty streak formation in fetal aortas and increased susceptibility to atherosclerosis later in life. Recent evidence indicated that selective B and T cell- dependent postnatal immune responses are also programmed in utero by mechanisms independent of transplacental passage of immunoglobulins, and that this can be influenced by maternal adaptive immunity prior to pregnancy. Maternal immunization with OxLDL, an antigen prevalent in atherosclerotic lesions, enhanced specific IgM immune responses and markedly reduced atherosclerosis in adult offspring. Given the importance of immune mechanisms and inflammation in both maternal conditions and offspring athero-genesis, we propose to further investigate the mechanisms of in utero immune programming and the protective effects of maternal immunomodulation. Specifically, we will: 1) establish that in utero programming of postnatal immune responses is not unique to OxLDL, by demonstrating that maternal immunization with other antigens, in particular diabetes-related ones, has similar consequences on immune programming and atherosclerosis;2) establish the role of maternal antibodies in developmental programming by determining whether passive maternal immunization protects offspring;3) determine whether prior immunization protects mothers against insulin resistance, and whether it protects offspring by increasing their insulin sensitivity, affecting splenic and arterial cytokine expression and T cell differentiation, and reducing atherogenesis under conditions of postnatal hypercholesterolemia, obesity, or insulin resistance;4) use immune-deficient models lacking B or T cells to establish whether the antiatherogenic effect of maternal OxLDL immunization in offspring is due to humoral or cellular mechanisms;and 5) use a novel strategy to generate monoclonal antibodies and antigen-independent B cells that are differentially expressed in offspring of immunized mothers, and establish their antiatherogenic effect.
These studies will elucidate essential mechanisms of developmental immune programming and may define new therapeutical strategies and tools to reduce cardiovascular disease in offspring of mothers with gestational insulin resistance and diabetes. They may also reduce the susceptibility of offspring to other immune-modulated disease, and lead to new immunoprevention of insulin resistance, in general.
