The Myeloid-T Lymphocyte Axis in Chronic Lung Allograft Rejection: Emerging Insights into the Immune Circuitry...

While lung transplantation is a life-saving treatment option for patients with end-stage lung diseases, its long-term outcome is hampered by exceedingly high rates of chronic rejection, manifesting as chronic lung allograft dysfunction (CLAD). It has long been recognized that exposure of the lung to the external environment via the airways, coupled with its rich immune microenvironment, makes the lung uniquely susceptible to heightened alloimmunity. Extensive immunosuppressive drugs do not provide effective control of the process of chronic rejection, and so, in recent years, investigators have turned their attention toward the identification of underlying cellular mechanisms that are either inherently resistant to or evolve to escape these medications. In this review, we explore recent advances in identifying the cellular mediators of chronic lung allograft rejection, with a focus on the myeloid-T cell immune axis, which will require targeted therapeutic approaches in the future to prevent irreversible allograft fibrosis.