RESUMO
BACKGROUND: Vascularized composite allografts (VCA) are novel, life-enhancing forms of transplantation (Tx). However, host immune responses to the various VCA components, especially those involving skin, are complex and make selection of appropriate therapy challenging. Although the interplay between Foxp3+ T regulatory (Treg) cells and CD4 and CD8 effector T cells is of central importance in determining the acceptance or rejection of solid organ allografts, there is little information available concerning the contribution of Treg cells to VCA survival. In addition, the effects of therapeutic expansion in vivo of host Treg cell populations on VCA survival are unknown. METHODS: We established a fully major histocompatibility complex-disparate (BALB/c- > C57BL/6) murine orthotopic forelimb Tx model to explore the benefits of pre- and post-Tx IL-2/anti-IL-2 monoclonal antibody complex (IL-2C) administration to expand the host Treg cell population and thereby attempt to promote Treg cell-dependent VCA survival. RESULTS: Both strategies expanded the Treg cell population in vivo and prolonged VCA survival (P < 0.001), but IL-2C administration pre-Tx led to significantly longer survival compared with IL-2C administration post-Tx (P < 0.01). In addition, compared with post-Tx therapy, pre-Tx therapy resulted in an increased ratio of Treg cells to CD8+ T cells (P < 0.001), reduced proliferation of CD4 and CD8 effector T cells, and reduced production of IFN-γ. Optimal effects were seen when combined with rapamycin therapy, whereas the combination of IL-2C therapy plus calcineurin inhibitor was counterproductive. CONCLUSIONS: Our studies involving different IL-2C-mediated Treg cell expansion strategies demonstrate that pre-Tx IL-2C therapy may be a useful component for developing strategies to promote VCA survival.
Assuntos
Aloenxertos Compostos , Membro Anterior/transplante , Sobrevivência de Enxerto/efeitos dos fármacos , Interleucina-2/farmacologia , Animais , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Linfócitos T Reguladores/imunologiaRESUMO
ABSTRACT We previously revealed the involvement of extracellular regulated protein kinases 1/2 (ERK1/2) in interleukin-6 (IL-6) secretion induced by cyclic compressive force (CCF) in MLO-Y4 cells. In this study, we investigated the contributions of the p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways to IL-6 secretion by stimulating MLO-Y4 cells with CCF. At 80% confluence, different magnitudes (1000μstrain, 2000 μstrain and 4000 μstrain), frequencies (0.5 Hz, 1.0 Hz and 2.0 Hz) and durations (10 min, 30 min, 1 h, 3 h and 6 h) of CCF were loaded onto cells using a four-point bending system. Flow Cytometry (FCM) analysis was used to analyze cell mortality rates after CCF loading. p38 and p65 phosphorylation as well as IκBα degradation in MLO-Y4 cells were detected by Western blotting (WB). Changes in IL-6 secretion after inhibitor treatment were assessed by enzyme-linked immunosorbent assays (ELISAs). Cellular viability was over 90 percent after CCF. p38 and p65 phosphorylation increased under all conditions, whereas IκBα protein levels decreased. However, phosphorylation and degradation were not completely dependent on the loading magnitude, frequency or duration. Furthermore, p38 inhibition using the specific inhibitor SB203580 reduced both p38 phosphorylation and IL-6 secretion. Similarly, NF-κB inhibition using BAY 11-7082 decreased p65 phosphorylation and IL-6 secretion but increased the concentration of IκBα. These findings reveal significant roles for the p38 and NF-κB signaling pathways in IL-6 secretion induced by CCF in MLO-Y4 cells.