Prolongation of Skin Graft Survival by Exogenous Ubiquitin

Abstract

Recently, it was shown that exogenous ubiquitin has anti-inflammatory actions in vivo and that the ubiquitin-decapeptide 50-59 has immunosuppressive effects similar to cyclosporine. Immunosuppressive effects of the native ubiquitin molecule and its therapeutic potential in transplantation are unknown. We tested the hypothesis that ubiquitin inhibits alloreactivity and increases allograft survival in a murine model of skin transplantation in fully mismatched strain combinations (C3H/HEJ-DBA2). Ubiquitin dose-dependently inhibited mixed leukocyte reaction in C3H/HEJ splenocytes in vitro. Intraperitoneal ubiquitin administration (25 microg/h for 14 days) was well-tolerated, dose-dependently increased ubiquitin serum concentrations and median allograft survival from 10 days (with albumin; control) to 17 days in DBA2 mice (survival ratio: 1.7, 95% confidence interval: 1.266-2.134; P=0.0005). The in vivo effects in this study combined with our previous work strongly indicate that ubiquitin is a potent immune modulator with broad therapeutic potential. Ubiquitin treatment could be a novel strategy to improve immunosuppressive regimens in transplantation.

Initial Assessment of the Role of CXC Chemokine Receptor 4 after Polytrauma

“…It also prevented the increase in blood lactate levels that was detectable in animals after vehicle and AMD3100 administration, suggesting that CXCR4 activation with exogenous ubiquitin normalizes impaired tissue metabolism during the shock phase (66)(67)(68)(69). Thus, in combination with the therapeutically relevant effects of SDF-1α, SDF-1α-derived proteins and ubiquitin, which have been reported previously (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), the findings from the present study further point toward CXCR4 as a promising drug target for trauma patients. …”

“…AMD3100 (generic name Plerixafor) was approved by the U.S. Food and Drug Administration to be used in combination with granulocytecolony stimulating factor to mobilize hematopoietic stem cells to the bloodstream in patients with non-Hodgkin lymphoma and multiple myeloma (36). On the basis of available data on the role of endogenous extracellular ubiquitin after trauma in patients (16,17), its inhibitory effects on leukocyte function upon pattern recognition receptor (PRR) activation (16,25,37) and the therapeutically relevant actions of CXCR4 agonists in various animal models (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), we hypothesized that blockade of ligand binding to CXCR4 will enhance proinflammatory responses of leukocytes and result in adverse effects when animals are subjected to severe trauma. Thus, we studied the pathophysiological response to trauma after blockade of CXCR4 with AMD3100 in a large animal model, which was designed to mimic the typical blunt polytrauma patient.…”

“…Although the regulation of SDF-1α levels after trauma and its association with clinical outcomes are largely unknown, administration of SDF-1α and of various SDF-1α mimetic proteins have been shown to result in beneficial effects in models of acute infectious and sterile inflammation in vivo (18)(19)(20)(21)(22). Similarly, treatment with exogenous ubiquitin has been shown to attenuate inflammation and to confer organ protection in animal models, including various models of trauma and hemorrhage (23)(24)(25)(26)(27)(28)(29)(30). Collectively, these studies imply CXCR4 as a promising drug target for trauma patients and suggest that CXCR4 may play an important role during the inflammatory response to tissue injury.…”

Structural Determinants of Ubiquitin-CXC Chemokine Receptor 4 Interaction

“…Ubiquitin, SDF-1␣, and a SDF-1␣ peptide analog have been shown to reduce exuberant inflammation and organ injury in various disease models (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)48). Thus, our findings provide the basis for the structure-based design of novel compounds that interact with ligand-specific binding sites and thus may permit targeting of selective therapeutic effects that are mediated through CXCR4.…”

“…Administration of the cognate ligand of CXCR4, stromal cell-derived factor-1␣ (SDF-1␣; chemokine (CXC motif) ligand 12) and of ubiquitin has been shown to result in anti-inflammatory and organ protective effects in various disease models (13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Despite these similarities, we showed previously that ubiquitin, unlike SDF-1␣, does not reduce HIV-1 infectivity (23).…”