Long-term islet allograft survival by peri-transplant antioxidant therapy combined with LFA-1 blockade

C. Fotino¹, R. Damaris Molano¹, E. Zahr-Akrawi¹, J. Molina¹, M. Lopez-Cabezas¹, G. Merizzi², A. Soleti², L. Inverardi¹, C. Ricordi³, A. Pileggi^4
1 Diabetes Research Institute, University of Miami, Miami, USA; ² Medestea Research, Turin, Italy; ³ University of Miami / Diabetes Research Institute, Departments of Surgery, Medicine, Microbiology & Immunology, and Biomedical Engineering; Jackson Memorial Hospital – and University of Miami Transplant Institute, Miami, USA; ⁴ University of Miami / Diabetes Research Institute, Departments of Surgery, Microbiology & Immunology, Miami, USA

Objective: To evaluate the impact on islet allograft survival of antioxidant therapy in combination with blockade of Lymphocyte Function Associated Antigen-1 (LFA-1) in a fully MHC-mismatched allogeneic islet transplantation model.

Methods: C56BL/6 (H-2^b) mice were rendered diabetic with streptozotocin and then received under the kidney capsule DBA/2(H-2^d) islets pre-cultured or not with the antioxidant Decanedioicacid bis(1-hydroxy-2,2,6,6-tetramethylpiperidin-4-yl)diester dihydrochloride(Iacvita, IAC; 100uM). Recipient treatments consisted of intraperitoneal administration of 100ug daily for 1 week of anti-LFA-1 antibody (KBA clone) and/or 15-day antioxidant treatment with 15mg/kg/day IAC. Control mice received no treatment or vehicle. Graft survival was monitored on nonfasting glycemic values (rejection was defined as NFG<200mg/dL).

Results: IAC treatment alone was associated with a MST of 7 (6-100)and 17 (12-19) days (n=3 and 4, respectively with or without in vitro IAC; p=N.S.). Anti-LFA-1 alone resulted in long-term (>100 days) survival in 62.5% of the recipients (n=8; p=0.03 vs. control). Combinatorial treatment yielded 100% long-term (>100 days) graft survival (n=3 and n=4,respectively, with or without in vitro IAC; p<0.014 vs. control; p<0.03vs. IAC). Control animals rejected their grafts with a median survival time (MST) of 15 (range7-24) days (n=12).

Conclusions: Peri-transplant treatment with anti-LFA-1 antibody results in long-term survival of islet allografts in only a proportion of the recipients. Combinatorial treatment of anti-LFA-1 Ab with IAC, an antioxidant drug, resulted synergistic in this model with all animals maintaining a functional graft long-term. The use of antioxidants, such as IAC, may represent a viable strategy to enhance the success of tolerance inducing protocols.