Qing-Fei-Pai-Du-Tang ameliorates lipopolysaccharide-induced rat acute lung injury through attenuating pulmonary microcirculatory disturbances via multi-target regulation.

BACKGROUND

Acute lung injury (ALI) rapidly progressing into acute respiratory distress syndrome (ARDS) is a major cause of the high fatality rate in acute respiratory infectious diseases. Qing-Fei-Pai-Du-Tang (QFPDT) has a clinical advantage in ALI/ARDS treatment. However, whether QFPDT can improve multiple pathological process involved in pulmonary microcirculatory disturbances during ALI, and the underlying mechanisms remain unclear.

PURPOSE

The present study aimed to assess the role of QFPDT in a lipopolysaccharide (LPS)-induced ALI rat model, attempting to disclose the rationale behind the effects of QFPDT.

METHODS

Male Wistar rats were intraperitoneally injected with LPS (7.5 mg/kg), and received QFPDT (6 g/kg) by gavage either 10 min before (pre-treatment) or 6 hours after (post-treatment) LPS injection. Intravital microscopy, histology, immunohistochemistry and immunofluorescence, flow cytometry, enzyme-linked immunosorbent assay, Western blotting, and proteomics analysis were utilized to investigate the effects and mechanisms of QFPDT. Chemical profiling of QFPDT was performed to identify potential active ingredients.

RESULTS

The results revealed that 6 and 24 hours after LPS injection induced a hyper-inflammatory and hyperpermeability process in rat lung tissues. Pre- and post-treatment with QFPDT attenuated the increase in leukocyte adhesion to pulmonary venules, accompanied by high expression of CD11b and intercellular adhesion molecule-1. Besides, QFPDT attenuated the LPS-induced increase in fluorescein isothiocyanate-dextran leakage from pulmonary microvessels, along with a downregulated expression of junction proteins and an upregulated expression and phosphorylation of Caveolin-1. Moreover, there was a downregulated expression of basement membrane proteins, increased matrix metalloproteinase-9 and cleaved Cathepsin B, and decreased ATP/ADP and ATP/AMP ratios after LPS, all of which were attenuated by QFPDT. Proteomics data evaluated by gene set enrichment analysis, QFPDT pharmacokinetic analysis, combined with molecular docking prediction and surface plasmon resonance validation revealed that QFPDT contained lung-entering prototype ingredients that improved ALI by regulating various key signaling pathway proteins associated with leukocyte adhesion, microvascular hyperpermeability, basement membrane degradation, and oxidative stress.

CONCLUSION

The present study demonstrates the multifaceted effects of QFPDT and offers insight into better understanding its underlying mechanisms in attenuating LPS-induced pulmonary microcirculatory disturbances and lung dysfunction through a multi-component and multi-target mode, thereby providing evidence supporting the application of QFPDT in ALI/ARDS-related diseases.