Milonine Protects Against Acute Lung Injury By Modulating The Akt And NF-κB Signaling Pathway

Acute lung injury (ALI) is an inflammation that triggers acute respiratory distress syndrome (ARDS) with perialveolar neutrophil infiltration, alveolar-capillary barrier damage, and lung edema. Activation of the toll-like receptor 4 complex and its downstream signaling pathways are responsible for the cytokine storm and cause alveolar damage on ARDS. Due to the complexity of inflammatory events on ALI, a defined pharmacotherapy has not been established. Thus, this study aimed to evaluate the anti-inflammatory potential of milonine, an alkaloid of Cissampelos sympodialis Eichl, in an ALI experimental model. BALB/c mice were lipopolysaccharide (LPS)-challenged and treated with milonine at 2.0 mg/kg. Twenty-four hours later, the bronchoalveolar lavage fluid (BALF), peripheral blood, and lungs were collected for cellular and molecular analysis. The milonine treatment decreased the inflammatory cell migration (principally neutrophils) to the alveolar cavity, the protein exudate, the pulmonary edema, and the level of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) into the BALF. The systemic level of IL-6 level was also reduced. In the lung tissue, milonine reduced the bronchoalveolar damage. The milonine docking analyzes demonstrated that the molecule formed hydrophobic interactions with the amino-acids Ile124 and Phe126 of the TLR4/MD2 groove. Indeed, the anti-inflammatory effect of milonine was due to the negative regulation of cytoplasmic kinase-Akt and NF-κB by interacting with the TLR4/MD2 complex. Therefore, milonine is an effective inflammatory modulator by blocking the interaction of the LPS-TLR4/MD2 complex and downregulating the intracellular inflammatory pathway axis being a potential molecule for the treatment of ALI.