Combination of Anti-CD4 with Anti-LFA-1 and Anti-CD154 Monoclonal Antibodies Promotes Long-Term Survival and Function of Neonatal Porcine Islet Xenografts in Spontaneously Diabetic NOD Mice

Abstract

Type 1 diabetes mellitus (T1DM) is caused by the autoimmune destruction of pancreatic islet β-cells, which are required for the production of insulin. Islet transplantation has been shown to be an effective treatment option for T1DM; however, the current shortage of human islet donors limits the application of this treatment to patients with brittle T1DM. Xenotransplantation of pig islets is a potential solution to the shortage of human donor islets provided xenograft rejection is prevented. We demonstrated that a short-term administration of a combination of anti-LFA-1 and anti-CD154 monoclonal antibodies (mAbs) was highly effective in preventing rejection of neonatal porcine islet (NPI) xenografts in non-autoimmune-prone B6 mice. However, the efficacy of this therapy in preventing rejection of NPI xenografts in autoimmune-prone nonobese diabetic (NOD) mice is not known. Given that the current application of islet transplantation is for the treatment of T1DM, we set out to determine whether a combination of anti-LFA-1 and anti-CD154 mAbs could promote long-term survival of NPI xenografts in NOD mice. Short-term administration of a combination of anti-LFA-1 and anti-CD154 mAbs, which we found highly effective in preventing rejection of NPI xenografts in B6 mice, failed to promote long-term survival of NPI xenografts in NOD mice. However, addition of anti-CD4 mAb to short-term treatment of a combination of anti-LFA-1 and anti-CD154 mAbs resulted in xenograft function in 9/12 animals and long-term graft (>100 days) survival in 2/12 mice. Immunohistochemical analysis of islet grafts from these mice identified numerous insulin-producing β-cells. Moreover, the anti-porcine antibody as well as autoreactive antibody responses in these mice was reduced similar to those observed in naive nontransplanted mice. These data demonstrate that simultaneous targeting of LFA-1, CD154, and CD4 molecules can be effective in inducing long-term islet xenograft survival and function in autoimmune-prone NOD mice.

Targeting co-stimulatory pathways: transplantation and autoimmunity

“…49 Blockade of OX40 signalling synergizes with blockade of the CD28 and CD154 pathways in preventing T-cell activation and prolonging graft survival. 121 LFA-1 antagonism has also been shown to synergize with both CD28 99 and CD154 blockade alone, 122,123 and combined CD154 and CD28 blockade 96,124 to inhibit memory T-cell activation in models of type 1 diabetes and transplantation. The observed synergistic effects of blocking multiple co-stimulatory pathways is likely to be indicative of the redundancy that exists within T-cell co-stimulatory mechanisms, in that, blockade of multiple pathways with overlapping effects will be required in order to maximize efficacy and improve outcomes clinically.…”

Porcine Islet Xenotransplantation for the Treatment of Type 1 Diabetes

“…The mechanism of diabetes development is similar to that which is found in human type 1 diabetes patients, where autoreactive T cells infiltrate the islets and specifically attack the  cells (Anderson & Bluestone, 2005). Strategies that have been shown to be effective in chemically induced diabetic mice have not been effective in NOD mice (Arefanian et al, 2007;Koulmanda et al, 2003). For example in our experience, the short-term administration of 2 monoclonal antibodies targeted against T cell activation failed to promote survival of NPI xenografts in NOD mice despite being highly effective in B6 mice.…”

“…For example in our experience, the short-term administration of 2 monoclonal antibodies targeted against T cell activation failed to promote survival of NPI xenografts in NOD mice despite being highly effective in B6 mice. Graft survival in the NOD mice required the administration of an additional monoclonal antibody against CD4 + T cells (Arefanian et al, 2007). Koulmanda et al have also demonstrated that the depletion of CD4 + T cells in NOD mice allowed for the prolonged survival of adult porcine islet xenografts.…”

“…These precursor cells allow the islets to differentiate and divide in the post-transplantation period (Binett et al, 2001;Hering & Walawalker, 2009;Korbutt et al, 1996;Rayat et al, 1999). NPI have been shown to reverse diabetes in both small and large animal models, including non-human primate (NHP) models, after a delay of up to 8 weeks due to their immaturity (Arefanian et al, 2007;Arefanian et al, 2010;Cardona et al, 2006;Kobayashi et al, 2005;Korbutt et al, 1996;Rayat & Gill, 2005;Ramji et al, 2010). They are also believed to be more resistant to hypoxic injury and less immunogenic than adult islets (Bloch et al, 1999).…”

Blockade of Leukocyte Function Antigen-1 (LFA-1) in Clinical Islet Transplantation

“…The impact of a short-term anti-LFA-1 antibody treatment alone in spontaneously diabetic NOD mice was partially efficacious, resulting only in delayed allograft rejection [12]. A synergistic effect was observed when combining extended anti-LFA-1 antibody treatment with costimulation blockade (ie, CTLA4Ig or CD154 antibody), with T-cell depletion or immunosuppression (ie, mTOR inhibitors) in spontaneously diabetic NOD mice receiving allogeneic or xenogeneic islet grafts [12,21].…”