Current data indicates that between 10-20% of patients that receive renal transplants experience acute rejection. Acute rejection is an important predictor of future complications that can lead to complete graft loss. Serine Protease Inhibitor proteins (Serpins) have shown incredible promise in working to lessen or inhibit the onset and effects of acute rejection in multiple solid organ transplant studies. However, it has been proposed that the mechanisms of Serp-1 immunomodulation can be affected by the native gut microbiome of recipient animals. This study utilizes murine renal allograft transplant from C57BL/6 to BALB/c and microbiome depletion to model the acute rejection response and to determine if there are interactions between the gut microbiome and Serp- 1 during the acute renal allograft rejection response. After antibiotic administration, expected decreases in richness and diversity in the designated group were observed. After renal subcapsular allograft transplant, histological and microbiome analyses revealed neither significant microbiome changes persistent after surgery based on pre-treatment nor changes associated with the administration of the isolated Serp-1 protein. Additionally, it was found that Serp-1 improves the histological presentation of acute renal allograft rejection regardless of the status of the microbiome.

The need of organs for transplantation has become an increasing medical need due to a limited donor organ supply. Many organs fail within 10 years due to acute and chronic rejection. Acute or antibody mediated rejection leads to decreased long term graft survival and increases the need for a repeat transplant. In prior work, reducing endothelial heparan sulfation and blockade of chemokine-glycosaminoglycan (GAG) interaction with Myxomavirus-derived protein, M-T7, reduced aortic and renal graft vascular inflammation and rejection. Conditional endothelial Ndst1 deficiency and inhibition of chemokine-GAG interaction reduces early allograft damage and suggest new therapeutic options for graft rejection. Here acute renal rejection was examined in grafts with conditional endothelial N-deacetylase-N-sulfotransferase-1 knockout (Ndst1-/-) and in wildtype (WT) C57Bl6/J grafts treated with saline, M-T7, antisense oligonucleotides (ASO) for Ndst1 or a scrambled ASO control. Viruses have a highly adaptive ability to evade hosts defense and immune response. The immunomodulatory proteins derived from viruses provide potential therapeutic uses to alleviate this need for organs. The Myxoma virus derived protein M-T7 is a promising therapeutic for reducing kidney transplant rejection. Orthotopic transplantations in mice are extremely difficult and costly because they require a highly trained microsurgeon. This kidney to kidney subcapsular and subcutaneous transplant model is a practical and simpler method that requires fewer mice, one kidney can be used for transplants in 6 or more mice and there is much lower morbidity, pain and mortality. Heterotopic transplantation of allografts is a simple model for preliminary testing of treatments for early inflammation, ischemia, and graft rejection. Subcapsular kidney transplantation provides a first step approach to test virus-derived proteins as potential treatments to reduce transplant rejection and inflammation. This project reports on a broadly applicable platform on which to rapidly and conveniently test new treatments for transplant rejection. This finding will significantly lower the barrier to entry for labs which are interested in translating their laboratory findings to animal models of organ transplantation which is a complex surgical procedure, and thus accelerate the bench-to-bedside translation of novel, putative treatments for transplant rejection as an initial screening tool.