Efficacy and Molecular Mechanisms of Lotus Leaf Extract in the Treatment of Respiratory Inflammation

Exposure to particulate matter (PM) is a major contributor to several respiratory diseases in humans. In this study, we aimed to investigate the protective effects and underlying molecular mechanisms of lotus leaf ( Nelumbo nucifera Gaertn.) extracts (NNCI_E) against PM-induced respiratory damage using in vitro and in vivo models. NNCI_E treatment ameliorated PM-induced increase in oxidative stress in A549 cells and reduced inflammatory cell infiltration in the bronchoalveolar lavage fluid (BALF) of PM-exposed mice. In addition, NNCI_E treatment increased the total white blood cell count and lymphocyte levels in the serum of PM-exposed mice and downregulated the expression of inflammatory mediators and cytokines in the BALF and lung tissues, respectively. Histopathological and molecular biomarker analyses demonstrated that NNCI_E treatment attenuated PM-induced respiratory dysfunction indicators, as evidenced by a significant reduction in serum symmetric dimethylarginine levels, and successfully ameliorated PM-induced lung damage. Mechanistically, the protective effects of NNCI_E against PM-induced damage were associated with the modulation of pyroptosis-associated markers and the potential inhibition of PM-induced activation of the mitogen-activated protein kinase and nuclear factor kappa B pathways. In conclusion, these findings suggest the potential of NNCI_E as a therapeutic agent against PM-induced respiratory injury.