AP
Improved mouse models for type 1 diabetes (T1D) therapy development are needed. T1D susceptibility is restored to normally resistant NOD.ß2m-/- mice transgenically expressing human disease-associated HLA-A*02:01 or HLA-B*39:06 class I molecules in place of their murine counterparts. T1D is dependent on pathogenic CD8+ T-cell responses mediated by these human class I variants. NOD.ß2m-/--A2.1 mice were previously used to identify ß-cell autoantigens presented by this human class I variant to pathogenic CD8+ T cells and for testing therapies to attenuate such effectors. However, NOD.ß2m-/- mice also lack nonclassical MHC I family members, including FcRn, required for antigen presentation, and maintenance of serum IgG and albumin, precluding therapies dependent on these molecules. Hence, we used CRISPR/Cas9 to directly ablate the NOD H2-Kd and H2-Db classical class I variants either individually or in tandem (cMHCI-/-). Ablation of the H2-Ag7 class II variant in the latter stock created NOD mice totally lacking in classical murine MHC expression (cMHCI/II-/-). NOD-cMHCI-/- mice retained nonclassical MHC I molecule expression and FcRn activity. Transgenic expression of HLA-A2 or -B39 restored pathogenic CD8+ T-cell development and T1D susceptibility to NOD-cMHCI-/- mice. These next-generation HLA-humanized NOD models may provide improved platforms for T1D therapy development.
Calcineurin inhibitors (CNI), used frequently in solid organ transplant patients, are known to inhibit T cell proliferation, but their effect on humoral immunity is far less studied. Total and naive B cells from healthy adult donors were cultured in immunoglobulin (Ig)A- or IgG/IgE-promoting conditions with increasing doses of cyclosporin, tacrolimus, rapamycin or methylprednisolone. The effect on cell number, cell division, plasmablast differentiation and class-switching was tested. To examine the effect on T follicular helper (Tfh) cell differentiation, naive CD4(+) T cells were cultured with interleukin (IL)-12 and titrated immunosuppressive drug (IS) concentrations. Total B cell function was not affected by CNI. However, naive B cell proliferation was inhibited by cyclosporin and both CNI decreased plasmablast differentiation. Both CNI suppressed IgA, whereas only cyclosporin inhibited IgE class-switching. Rapamycin had a strong inhibitory effect on B cell function. Strikingly, methylprednisolone, increased plasmablast differentiation and IgE class-switching from naive B cells. Differentiation of Tfh cells decreased with increasing IS doses. CNI affected humoral immunity directly by suppressing naive B cells. CNI, as well as rapamycin and methylprednisolone, inhibited the in-vitro differentiation of Tfh from naive CD4(+) T cells. In view of its potent suppressive effect on B cell function and Tfh cell differentiation, rapamycin might be an interesting candidate in the management of B cell mediated complications post solid organ transplantation.
