The preliminary efficacy evaluation of the CTLA-4-Ig treatment against Lupus nephritis through in-silico analyses.

The humanized cytotoxic T lymphocyte-associated antigen 4 immunoglobulin (CTLA-4-Ig) has been used to treat Lupus nephritis (LN) based on CTLA-4s negative regulation of T-cell activation through competent to binding with CD80/CD86, the inherent genetic factors influencing the CTLA-4-Ig treatment efficacy are widely unknown. Here, 62 nonsynonymous single nucleotide variants (nsSNVs) of CTLA-4 gene, 184 of CD80 and 201 of CD86 were identified and validated within both EMBL-EBI and dbSNP databases. Next, the nsSNVs rs1466152724 in CTLA-4, rs1196816748, rs765515058, rs1157880125, rs1022857991, and rs142547094 in CD80 and rs1203132714 in CD86 were consistently suggested to be deleterious by SIFT, PolyPhen-2, PROVEAN and meta LR. Based on the 3D structure stability analysis, the variant rs765515058 causing G167V in CD80 was found to reduce the protein's stability through changing the characters of constructed structure of complete CD80 apo form and stabilizing amino acid residues of CD80 holo form in a great degree. Furthermore, the interaction energy analysis results suggested that rs1022857991 causing C50F may reduce the binding energy of CTLA-4 with CD80. Along with the increasing variants, these nsSNVs' effects on the interaction of CTLA-4 with CD80/CD86 will increase, and thus influence the CTLA-4-Ig treatment efficacy against LN.

Quantification of Alloantibody-Mediated Cytotoxicity In Vivo.

BACKGROUND: Preexisting, donor-specific antibodies (DSAs) are culprits of hyperacute rejection. Donor-specific antibodies are also formed de novo, and their role in acute and chronic rejection is increasingly appreciated. However, it is difficult to assess damage inflicted exclusively by DSAs when alloreactive T cell and B cell responses coincide. We reasoned that allosensitization with "costimulation-deficient" cells should induce DSA synthesis but not naive cytotoxic T lymphocyte (CTL) precursors' priming via direct allorecognition. Accordingly, we have developed a novel model to quantify DSA-mediated cytotoxicity in vivo. METHODS: C57BL/6 (H-2b) mice were sensitized with H-2 kidney epithelial cells, and a cytofluorimetric killing assay was tailored to the measurement of allocytotoxicity. We took cell/complement depletion, costimulation blockade, and serum transfer approaches to reveal the mediators of cytotoxicity. "Third-party" controls and a skin allotransplantation model were used to confirm DSAs' specificity for allo-major histocompatibility complex. We validated our experimental approach in other mouse strains primed with different allogeneic cell types, including endothelial cells. To demonstrate the usefulness of our model/method for drug efficacy testing, we examined the effect of CTLA4-Ig and rapamycin on DSA-mediated cytolysis. RESULTS: Allosensitization of MHC-disparate mouse strains with costimulation-deficient cells led to robust cytotoxicity mediated by complement-fixing DSAs and phagocytic cells. This response was independent of CTLs, natural killer or natural killer T cells. It required CD4 T cell help, CD40 signaling and CD28-based costimulation during allosensitization and could be reversed by sustained rapamycin treatment. CONCLUSIONS: The unique model described herein should enable mechanistic studies on sensitization and effector phases of humoral alloreactivity as well as efficacy testing of future immunotherapies to prevent DSA-induced pathology.

Hyperlipidemia Alters Regulatory T Cell Function and Promotes Resistance to Tolerance Induction Through Costimulatory Molecule Blockade.

Recent work from our laboratory has shown that hyperlipidemia promotes accelerated rejection of vascularized cardiac allografts in mice by inducing anti-donor Th17 reactivity and production of IL-17. Here, we show that hyperlipidemia also affects FoxP3(+) regulatory T cells (Tregs). Hyperlipidemia promotes the development of Tregs that express low levels of CD25. Hyperlipidemia also promotes a decrease in central Tregs and an increase in effector Tregs that appears to account for the increase in the frequency of CD25(low) Tregs. Alterations in Treg subsets also appear to lead to alterations in Treg function. The ability of FoxP3(+) , CD25(high) , CD4(+) Tregs from hyperlipidemic mice to inhibit proliferation of effector T cells stimulated with anti-CD3 and CD28 was reduced when compared with Tregs from control mice. Regulatory T cells isolated from hyperlipidemic recipients exhibit increased activation of Akt, and a reduction in Bim levels that permits the expansion of FoxP3(+) CD25(low) CD4(+) T cells. Hyperlipidemic mice were also resistant to tolerance induction using costimulatory molecule blockade consisting of anti-CD154 and CTLA4Ig, a strategy that requires Tregs. Together, our data suggest that hyperlipidemia profoundly affects Treg subsets and function as well as the ability to induce tolerance.