AS-703026 Inhibits LPS-Induced TNFa Production through MEK/ERK Dependent and Independent Mechanisms

Chronic obstructive pulmonary disease (COPD) is characterized by intense lung infiltrations of immune cells (macrophages and monocytes). Lipopolysaccharide (LPS) activates macrophages/monocytes, leading to production of tumor necrosis factor a (TNF alpha) and other cytokines, which cause subsequent lung damages. In the current study, our results demonstrated that AS-703026, a novel MEK/ERK inhibitor, suppressed LPS-induced TNF alpha mRNA expression and protein secretion in RAW 264.7 murine macrophages, and in murine bone marrow-derived macrophages (BMDMs). Meanwhile, TNF alpha production in LPS-stimulated COPD patents' peripheral blood mononuclear cells (PBMCs) was also repressed by AS-703026. At the molecular level, we showed that AS-703026 blocked LPS-induced MEK/ERK activation in above macrophages/monocytes. However, restoring ERK activation in AS-703026-treated RAW 264.7 cells by introducing a constitutive-actively (CA)-ERK1 only partially reinstated LPS-mediated TNF alpha production. Meanwhile, AS-703026 could still inhibit TNF alpha response in ERK1/2-depleted (by shRNA) RAW 264.7 cells. Significantly, we found that AS-703026 inhibited LPS-induced nuclear factor kappa B (NF kappa B) activation in above macrophages and COPD patients' PBMCs. In vivo, oral administration of AS-703026 inhibited LPS-induced TNF alpha production and endotoxin shock in BALB/c mice. Together, we show that AS-703026 in vitro inhibits LPS-induced TNF alpha production in macrophages/monocytes, and in vivo protects mice from LPS-induced endotoxin shock. Thus, it could be further studied as a useful anti-inflammatory therapy for COPD patients.