DEVELOPMENT OF A REGULATORY T CELL MIMETIC FOR TOLERANCE INDUCTION IN SKIN TRANSPLANTATION

In this competitive revision we propose to formulate a second generation of regulatory T cell (Treg) mimetic byincluding adenosine (ADO) to the biomaterials system, from muxTIC (TGF-β1, IL-10, and CTLA-4Ig) tomuxTICA. The purpose is to investigate the mechanistic aspects of muxTICA as a locally-delivered (bronchialinstillation) therapeutic for acute respiratory distress syndrome (ARDS). We will test the capacity of thecombined immunosuppressive factors to skew alveolus macrophages to an anti-inflammatory phenotype in apro-inflammatory microenvironment. The experiments involve testing the agents in vitro using alveolarmacrophage lines, in human 3D airway epithelial tissues, and in a microfluidic shear cellular system.The rationale for exploring the immunosuppressive strategy is that COVID-19-induced ARDS is associatedwith excessive inflammation, characterized by rapid surges of pro-inflammatory cytokines such as IL-1β, IL-17,IL-6 and TNFα. The clinical picture akin to the cytokine storm immunopathology reported in the patientsinfected with the coronaviruses emerged in 2002 (`SARS") and 2012 ("MERS").Because corticosteroids arenot recommended and might exacerbate COVID-19-associated lung injury, novel immunosuppressivestrategies are urgently needed to mitigate the hyper-inflammation associated with ARDS.Clinical studies indicate that Tregs can ameliorate ARDS. Survivors of COVID-19 infections have higherblood-circulating Tregs than non-survivors, and patients with elevated TGF-β1 and IL-10 have betteroutcomes. Mechanistically Tregs limit lung fibrosis form infections and inhibit excessive virus-specific T cellresponses. A major driver of ARDS in COVID-19 infected patients is massive infiltration of macrophagesinfiltration, which produce pro-inflammatory cytokines and prorogate inflammation, resulting in lung fibrosis andalveolar edema. Tregs has the capacity to steer macrophages an M2 regulatory, anti-inflammatory phenotype.In addition to TGF-β1, IL-10, and CTLA-4Ig, another phenotype-defining factor of Tregs' immunosuppressiveeffects is ADO. In an animal model of ARDS, bronchial instillation of ADO reduces microvascular permeabilityin the lungs. Therefore, we will include ADO in the formulation to generate muxTICA.The experiments proposed are designed to advance an off-the-shelf immunosuppressant strategy as a logicalextension of the original specific aims in the context of an urgent medical need. Therefore, the studies in theoriginal and revision applications are conceptually and technologically synergistic and complementary.