Nox2-deficient Tregs improve heart transplant outcomes via their increased graft recruitment and enhanced potency

• Published in: JCI insight Vol. 6; no. 18
• Main Authors: Trevelin, Silvia C, Zampetaki, Anna, Sawyer, Greta, Ivetic, Aleksandar, Brewer, Alison C, Smyth, Lesley Ann, Marelli-Berg, Federica, Köchl, Robert, Lechler, Robert I, Shah, Ajay M, Lombardi, Giovanna
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 22.09.2021; American Society for Clinical investigation
• Subjects: Allografts - immunology; Allografts - metabolism; Allografts - pathology; Animals; Cardiology; CD8-Positive T-Lymphocytes - physiology; Cell Movement; Cell Proliferation; Female; Fibrosis; Graft Rejection - blood; Graft Rejection - immunology; Heart Transplantation; Immunology; Interferon-gamma - metabolism; Isoantibodies - blood; Male; Mice; Mice, Knockout; MicroRNAs - metabolism; Myocytes, Cardiac - pathology; NADPH Oxidase 2 - genetics; Necrosis; Receptors, CCR4 - metabolism; Receptors, CCR8 - metabolism; T-Lymphocytes, Regulatory - immunology; T-Lymphocytes, Regulatory - metabolism; Transplantation, Homologous; Troponin I - blood; Heart failure; Immunology; Cardiology; Cell migration/adhesion; Immunotherapy
• ISSN: 2379-3708; 2379-3708
• DOI: 10.1172/jci.insight.149301

Nox2 is a ROS-generating enzyme, deficiency of which increases suppression by Tregs in vitro and in an in vivo model of cardiac remodeling. As Tregs have emerged as a candidate therapy in autoimmunity and transplantation, we hypothesized that Nox2 deficiency in Tregs in recipient mice may improve outcomes in a heart transplant model. We generated a potentially novel B6129 mouse model with Treg-targeted Nox2 deletion (Nox2fl/flFoxP3Cre+ mice) and transplanted with hearts from CB6F1 donors. As compared with those of littermate controls, Nox2fl/flFoxP3Cre+ mice had lower plasma levels of alloantibodies and troponin-I, reduced levels of IFN-γ in heart allograft homogenates, and diminished cardiomyocyte necrosis and allograft fibrosis. Single-cell analyses of allografts revealed higher absolute numbers of Tregs and lower CD8+ T cell infiltration in Nox2-deficient recipients compared with Nox2-replete mice. Mechanistically, in addition to a greater suppression of CD8+CD25- T effector cell proliferation and IFN-γ production, Nox2-deficient Tregs expressed higher levels of CCR4 and CCR8, driving cell migration to allografts; this was associated with increased expression of miR-214-3p. These data indicate that Nox2 deletion in Tregs enhances their suppressive ability and migration to heart allografts. Therefore, Nox2 inhibition in Tregs may be a useful approach to improve their therapeutic efficacy.