Background/Purpose: The importance of beta-glycoprotein I (beta2GPI)-specific CD4+ T cells in the development of pathogenic processes in patients with antiphospholipid syndrome (APS) and APS mice models is well established. Tolerogenic dendritic cells (tDCs) have the potential to control the outcome of autoimmunity by modulating the immune response. Previously we showed that human tDCs induced  with IL-10 and TGFbeta1, loaded with beta2GPI ameliorated effector/memory CD4+ T cells response  in patients with APS in-vitro (Ann Rheum.Dis 2012). The aim of this study was to uncover the mechanisms that define the tolerogenic effect of beta2GPI or beta2GPI synthetic derivatives specific tDCs on experimental APS.

Methods:   tDCs were generated in-vitro from naïve mice bone marrow cells in the presence of TGFbeta  and IL-10, cDCs were supplemented with GM-CSF. All the DCs were LPS maturated, pulsed with beta2GPI or beta2synthetic derivatives control peptide and candidin and phenotyped by FACS.  miRNA expression were defined by RT-PCR and MAPKs by MAPKs protein-arrays. beta2GPI  T cell response to tDCs and cDCs by CFSC and FACS analyses. The tDCs and cDCs were subjected subcutaneously into mice with experimental APS induced by beta2GPI. CD4⁺CD25⁺FOXP3⁺ Treg cells were analyzed by FACS. Adoptive transfer experiments were conducted by passive transfer of Tregs from the tDCs –injected mice to APS mice. Cytokine expression of IFNgamma, IL-17, TGFbeta and IL-10 by RT-CR. 

Results: tDCs expressed miRNA 23b, 142-3p and 221, whereas  cDCs  were characterized in expression of miRNA 146a and miRNA155. tDCs  specific to beta2GPI and its synthetic derivative were able to decrease  b2GPI  response manifested by decreased beta2GPI  T cell response by 75%-87% while cDCs did not show any significant response, p<0.001.  Moreover, we were able to show inhibition of circulating anti-beta2GPI  antibodies titers (p<0.002) and inhibition of fetal loss by 67% was documented in tDCs recipient APS mice in comparison to 8% in the cDCs recipient mice , p<0.02. Enhanced expression of CD4+CD25+FOXP3+Tregs by 21% in tDCs injected mice in comparison to 5% in the cDCs injected APS mice was exemplified by FACS. Reduced expression of IFNgamma and L-17 by 5.2 times and enhanced expression of TGFbeta and IL-10  by 6.8 fold was illustrated by RT-PCR. A significant amelioration of  all the above parameters were noticed as well in the Treg transferred -APS recipient mice (e.g decreased beta2GPI T cell response, circulating anti-beta2GPI antibodies, and IFNgamma/IL-17). tDCs uploaded with beta2GPI had beneficial effect on the therapeutic properties than the beta2GPI synthetic derivatives, p>0.05. 

Conclusion: beta2GPI tDCS have the potential to ameliorate experimental APS by upregulation of Tregs and proinflammatory cytokines. beta2GPI tDCS may offer a novel approach for developing personalized therapy for APS patients.