In this competitive revision we propose to formulate a second generation of regulatory T cell (Treg) mimetic by including adenosine (ADO) to the biomaterials system, from muxTIC (TGF-?1, IL-10, and CTLA-4Ig) to muxTICA. The purpose is to investigate the mechanistic aspects of muxTICA as a locally-delivered (bronchial instillation) therapeutic for acute respiratory distress syndrome (ARDS). We will test the capacity of the combined immunosuppressive factors to skew alveolus macrophages to an anti-inflammatory phenotype in a pro-inflammatory microenvironment. The experiments involve testing the agents in vitro using alveolar macrophage 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 associated with excessive inflammation, characterized by rapid surges of pro-inflammatory cytokines such as IL-1?, IL-17, IL-6 and TNF?. The clinical picture akin to the cytokine storm immunopathology reported in the patients infected with the coronaviruses emerged in 2002 (`SARS?) and 2012 (?MERS?). Because corticosteroids are not recommended and might exacerbate COVID-19-associated lung injury, novel immunosuppressive strategies 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 higher blood-circulating Tregs than non-survivors, and patients with elevated TGF-?1 and IL-10 have better outcomes. Mechanistically Tregs limit lung fibrosis form infections and inhibit excessive virus-specific T cell responses. A major driver of ARDS in COVID-19 infected patients is massive infiltration of macrophages infiltration, which produce pro-inflammatory cytokines and prorogate inflammation, resulting in lung fibrosis and alveolar edema. Tregs has the capacity to steer macrophages an M2 regulatory, anti-inflammatory phenotype. In addition to TGF-?1, IL-10, and CTLA-4Ig, another phenotype-defining factor of Tregs' immunosuppressive effects is ADO. In an animal model of ARDS, bronchial instillation of ADO reduces microvascular permeability in 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 logical extension of the original specific aims in the context of an urgent medical need. Therefore, the studies in the original and revision applications are conceptually and technologically synergistic and complementary.
In this revision we seek to leverage the regulatory T cell mimetic proposed in the original application to mitigate the hyperinflammation in patients with acute respiratory disease syndrome (ARDS), a leading cause of death in the COVID-19 pandemic. The new experiments will delineate the efficacy and mechanistic aspects of the biomaterials-tethered Treg factors (TGF-?1, IL-10, CTLA-4Ig, and adenosine) on alveolus macrophages activated in vitro by pro-inflammatory cytokines found in patients with COVID-19 infections. The ultimate goal is to determine the potential of using the combined Treg factors to limit ARDS-induced lung fibrosis.
