IL-4 modulates reconstituted human T cells as a regulatory factor to mitigate GVHD in humanized mice model

Abstract

Abstract Allogeneic hematopoietic cell transplantation is an essential treatment in hematological diseases. However, graft-versus-host disease (GVHD) is the leading cause of the mortality and treatment failures in transplant recipients. In humanized mice engrafted with human peripheral-blood mononuclear cells (PBMCs), the rapid development of lethal xenogeneic GVHD is also a major model limitation that hinders long-term and precise immune analysis. Therefore, the study aims to suppressed GVHD symptoms in human PBMCs-engrafted humanized mice model for the study of human immune responses. We investigated whether supplementary of human IL-4 that modulate naïve T cells maturing and differentiating can lead to GVHD amelioration. Adeno-associated virus (AAV) vectors were used to express human cytokines in humanized mice. We first demonstrated that rAAV vectors allow sustained expression of human IL-4 in vivo. After injection of PBMCs, GVHD symptoms observed in NSG mice were significantly suppressed in human IL-4 expressing recipients, with the survival of originally less than two months to more than 7 months without body weight loss. Long-term engraftment of human T cells were also observed. Among the reconstituted human cells, CD4+ T cells were the dominant expanding subpopulation, comparing to CD8+ dominated cell proliferation in mice with GVHD development. In addition, significantly high levels of human IgG in humanized mice sera (1 mg/ml, comparable to human’s) were detected 5 months after PBMC transplantation, suggesting the potential use for long-term study of human humoral immune responses. In conclusion, human IL-4 expression by AAV vectors is an efficient strategy to ameliorate GVHD in PBMC-engrafted humanized mice model.