Evaluation of the Therapeutic Potential of eNAMPT Monoclonal Antibodies (mAbs) in Preclinical Models of Acute Lung Injury and ARDS

Abstract

Acute respiratory distress syndrome (ARDS) is a devastating inflammatory lung disease which results in acute respiratory failure. ARDS affects more than 400,000 individuals annually in the USA with high mortality rate (30–40%). Mechanical ventilation (MV) is an essential part of the current ARDS management. However, MV itself may lead to ARDS. There remains a serious unmet need for effective therapies for ARDS. Our previous lab results demonstrated that excessive mechanical stress induces spatially-localized nicotinamide phosphoribosyl-transferase (NAMPT) expression (1) with robust expression and secretion by lung endothelial cells (ECs) into the circulation with extracellular NAMPT (eNAMPT) a novel biomarker in ARDS (1, 2). We have used a polyclonal NAMPT antibody as a potential therapy in many preclinical ARDS animal models such as ventilator-induced Lung Injury (VILI) (3), LPS-induced inflammatory lung injury (4), pulmonary artery hypertension (PAH) (5), and radiation-induced lung injury (RILI) (12). Since the polyclonal antibodies cannot be used in humans, we next developed a mouse mAb that can neutralize eNAMPT in humans. From 2 murine eNAMPT mAbs, 2 were selected and 50 humanized mAbs generated. These were screened in vitro for eNAMPT neutralization and 7 humanized mAbs selected for evaluation in C57/BL6 mice (8–12 wks.) utilizing our preclinical LPS and two-hit (LPS+VILI) ALI models. We further designed an integrated ALI severity scoring system to evaluate responses these Abs. This scoring system is composed of four elements: total bronchoalveolar lavage (BAL) cell counts (CC), total BAL protein levels, lung tissue cell infiltration and alveolar wall thickness. Of the seven eNAMPT mAbs, UU, XX and P were the most effective in attenuating lung injury in our preclinical ARDS models. As a conclusion, application of IV delivered eNAMPT mAbs were evaluated in our integrated ALI severity scoring system with evaluation of eNAMPT mAbs UU, XX and P in large animal models of ARDS prior to evaluation as a therapeutic strategy in clinical trials for patients with ARDS.