Development of Novel RhoA Nitration Inhibitory Peptides for the Treatment of Acute Lung Injury - ABSTRACT Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) manifest with acute lung inflammation with increased vascular permeability. Treatment of ALI/ARDS patients with low-volume mechanical ventilation is the only proven therapy for ALI/ARDS, and mortality rates remain unacceptable. Because the syndrome of acute respiratory failure is so common in the United States and worldwide, especially in the face of relatively new respiratory viruses such as SARS-CoV-2, ALI/ARDS is an unmet medical need. Novel pharmacological therapies need to be developed to further improve clinical outcomes in ALI/ARDS patients. RhoA and Rac1 exert distinct effects on epithelial and endothelial barrier function via selective structural and biochemical modulation of junctional proteins. Rac1 and RhoA have antagonistic effects on endothelial barrier function in the lung. Rac1 is required for the assembly and maturation of endothelial junctions, whereas RhoA destabilizes endothelial junctions by increasing the isometric tension at the cell membrane, increasing myosin contractility. Our prior studies have linked RhoA nitration at (Tyr (Y)34) with its activation, endothelial barrier disruption, the disruption of mitochondrial network dynamics, mitochondrial function, and the activation of NF-kb dependent inflammation. A strategy has been designed to shield RhoA from nitration at Y34, protect endothelial barrier function, preserve mitochondrial function, and reduce inflammation during conditions that can cause ALI/ARDS. This strategy identified a small peptide, NipR1, which protects RhoA from nitration at Y34 and prevents LPS-induced peroxynitrite attack. NipR1 contains nine amino acids from 31–39 of RhoA fused with the cell-permeable TAT sequence. Natural peptides have poor absorption, distribution, metabolism, and excretion (ADME) properties with rapid clearance, short half-life, low permeability, and sometimes low solubility. Thus, in response to this special NHLBI RFA, a chemical approach will be utilized to identify more potent peptidomimetics of NipR1. In the R61 phase, we will generate ~100 compounds based on our newly identified pharmacophores and screen them using both in vitro and in vivo assays in multiple mouse models of ALI. In the R33 phase, we will generate two optimized NipR1 derivatives, conduct pharmacokinetics/pharmacodynamics (PK/PD) and safety studies, and confirm therapeutic effects using a pig model of sepsis. We anticipate these studies will allow us to identify a lead compound with desired in vitro and in vivo characteristics as a novel therapy for ALI/ARDS.
