No abstract

Pernicious anemia and gastric carcinoma are serious sequelae of autoimmune gastritis (AIG). Our study indicates that in adult C57BL/6 DEREG mice expressing a transgenic diphtheria toxin receptor under the Foxp3 promoter, transient Treg cell depletion results in long-lasting AIG associated with both H+K+ATPase and intrinsic factor autoantibody responses. Although functional Treg cells emerge over time during AIG occurrence, the effector T cells rapidly become less susceptible to Treg cell-mediated suppression. While previous studies have implicated dysregulated Th1 responses in AIG pathogenesis, eosinophils have been detected in gastric biopsies from patients with AIG. Indeed, AIG in DEREG mice is associated with strong Th2 responses, including dominant IgG1 autoantibodies, elevated serum IgE, increased Th2 cytokine production, and eosinophil infiltration in the stomach draining lymph nodes. Additionally, the stomachs exhibit severe mucosal and muscular hypertrophy, parietal cell loss, mucinous epithelial cell metaplasia, and massive eosinophilic inflammation. Notably, the Th2 responses and gastritis severity are significantly ameliorated in IL-4- or eosinophil-deficient mice. Furthermore, expansion of both Th2-promoting IRF4+PD-L2+ dendritic cells and ILT3+ rebounded Treg cells were detected after transient Treg cell depletion. Collectively, these data suggest that Treg cells maintain physiological tolerance to clinically relevant gastric autoantigens, and Th2 responses can be a pathogenic mechanism in autoimmune gastritis.

Human maternal autoantibodies can trigger autoimmune diseases such as congenital heart block (CHB) in the progeny of women with lupus or Sjogren’s disease. The pathogenic effect of early autoantibody (autoAb) exposure has been investigated in a murine neonatal autoimmune ovarian disease (nAOD) model triggered by a unique ZP3 antibody. Although immune complexes (IC) are formed in adult and neonatal ovaries, ZP3 antibody triggers severe nAOD only in <7-day-old neonatal mice. Propensity to nAOD is due to the uniquely hyper-responsive neonatal natural killer (NK) cells that lack the inhibitory Ly49C/I receptors. In nAOD, the neonatal NK cells directly mediate ovarian inflammation and oocyte depletion while simultaneously promoting de novo pathogenic ovarian-specific T cell responses. Resistance to nAOD in older mice results from the emergence of the Ly49C/I+ NK cells that regulate effector NK cells and from CD25+ regulatory T cell control. In preliminary studies, FcγRIII+ NK cells as well as the ovarian resident FcγRIII+ macrophages and/or dendritic cells were found to be as indispensable players. Activated by ovarian IC, they migrate to lymphoid organs where NK cell priming occurs. Remarkably, the findings in nAOD are very similar to those reported for neonatal responses to a retrovirus and its cognate antibody that lead to long-lasting immunity. Studies on nAOD therefore provide insights into maternal autoAb-mediated neonatal autoimmunity, including CHB, while simultaneously uncovering new properties of the neonatal innate and adaptive responses, lethality of premature infant infection, and novel neonatal antiviral vaccine design.