PEBL, a component-based Chinese medicine, reduces virus-induced acute lung injury by targeting FXR to decrease ACE2 levels

INTRODUCTION: Despite the growing clinical need, the therapeutic efficacy of drugs for acute lung injury (ALI) remains inadequate. Traditional Chinese Medicine (TCM) holds potential in managing ALI due to its unique therapeutic properties. However, the intricate nature of TCM formulations hinders global adoption. Component-based Chinese medicine (CCM) offers a promising pathway for TCM's internationalization. Phillyrin-Emodin-Baicalin-Liquiritin (PEBL), a CCM with significant anti-inflammatory activity, is derived from the well-established TCM formula Liang-Ge-San. Whether PEBL effectively addresses viral ALI, however, remains unclear. OBJECTIVES: This study aims to investigate the therapeutic effects and underlying mechanisms of PEBL on viral ALI. METHODS: The efficacy of PEBL against Poly(I:C)-induced ALI was assessed by analyzing cytokine production, macrophage infiltration, pulmonary damage, and mortality. Bioinformatics and network pharmacology were employed to identify key targets and signaling pathways. The molecular mechanisms were further validated using Poly(I:C)-treated RAW264.7 cells, Tg(coro1α: GFP) zebrafish, BALB/c mice, and models of Influenza A/Puerto Rico/8/1934 (H1N1) virus strain (PR8)-induced ALI in BALB/c mice and SARS-CoV-2 Omicron XBB.1.16 subvariant (XBB)-induced ALI in hACE2-transgenic C57BL/6 mice. RESULTS: PEBL mitigated Poly(I:C)-induced ALI, as evidenced by reduced cytokine levels, diminished macrophage infiltration, alleviated lung damage, and decreased mortality. Virtual screening identified the farnesyl X receptor (FXR) and angiotensin-converting enzyme 2 (ACE2) as key therapeutic targets for viral pneumonia. Mechanistically, PEBL downregulated FXR expression, inhibiting FXR binding to ACE2 promoters, which subsequently suppressed NF-κB-p65 nuclear translocation and cytokine production. In vivo, PEBL attenuated cytokine production by inhibiting ACE2 transcription through FXR downregulation, leading to alleviation of Poly(I:C)-induced ALI in both zebrafish and mice. Additionally, PEBL significantly improved symptoms of ALI caused by PR8 and XBB infections, by disrupting the FXR/ACE2 signaling axis, resulting in reduced weight loss, lower lung indices, diminished viral load and titer, fewer pulmonary lesions, and suppressed NF-κB-p65 nuclear translocation, along with decreased cytokine storm. CONCLUSIONS: This study provides the first evidence that PEBL offers protective effects against ALI induced by acute respiratory viruses. PEBL prevents FXR from binding to ACE2 by inhibiting FXR transcription, which reduces macrophage infiltration, cytokine storm formation, and inflammatory injury, thereby ameliorating viral ALI. These findings underscore the potential of PEBL as a candidate for further exploration in the treatment of viral ALI.