Complement Component C5 and Graft-Versus-Host-Disease

Abstract

Graft versus Host Disease (GvHD) is one of the main complications patients face after receiving a bone marrow transplant. Between 40-60% of bone marrow transplant recipients develop GvHD, with consequent systemic inflammation/fibrosis, reduced quality of life, graft failure, and mortality. We have previously demonstrated that donor-derived C5 is involved in the initiation and propagation of GvHD. Current approaches to inhibition of C5 share a serious flaw of indiscriminately blocking production of a mediator that is crucial for host defense. Targeted therapies to block C5 in specific cells, or anatomical sites, are the only way in which to achieve therapeutic benefit without compromising host defenses. Three lentiCRISPR v2-dCas9 gene editing viral constructs were created to selectively cleave the complement C5 gene, at three different sites. Our objective was to knockout complement C5 function in infected donor BM cells in a GVHD mouse model. Each of the three lentiCRISPR plasmids was separately co-cultured with PMDG2 and PSPAX2, in human embryonic kidney (HEK) 293T cells. Resultant viral particles were able to transfer the Cas-9 endonuclease gene into donor BM cells in vitro with a transduction efficiency of 52%. Treated donor BM cells were then retro-orbital injected into irradiated recipient mice. Control mice were transplanted following the same protocol excluding the lentiCRISPR treatment of BM. The lentiCRISPR treatment group demonstrated significantly lower total airway resistance (p = 0.05) and higher lung compliance (p = 0.014) when compared to the control group. When compared to the saline treated group however the lentiCRISPR group showed significantly higher total airway resistance (p = 0.004) and significantly lower lung compliance (p = 0.014). These results taken together suggest a possible reduction in GvHD severity in mice that received the lentiCRISPR treatment. This study can serve as a starting point for the development of this novel treatment of GvHD.