The efficacy and safety of pinocembrin in a sheep model of bleomycin-induced pulmonary fibrosis

PLoS One. 2021 Dec 2;16(12):e0260719. doi: 10.1371/journal.pone.0260719. eCollection 2021.

Abstract

The primary flavonoid, pinocembrin, is thought to have a variety of medical uses which relate to its reported anti-oxidant, anti-inflammatory, anti-microbial and anti-cancer properties. Some studies have reported that this flavonoid has anti-fibrotic activities. In this study, we investigated whether pinocembrin would impede fibrosis, dampen inflammation and improve lung function in a large animal model of pulmonary fibrosis. Fibrosis was induced in two localized lung segments in each of the 10 sheep participating in the study. This was achieved via two infusions of bleomycin delivered bronchoscopically at a two-week interval. Another lung segment in the same sheep was left untreated, and was used as a healthy control. The animals were kept for a little over 5 weeks after the final infusion of bleomycin. Pinocembrin, isolated from Eucalyptus leaves, was administered to one of the two bleomycin damaged lung segments at a dose of 7 mg. This dose was given once-weekly over 4-weeks, starting one week after the final bleomycin infusion. Lung compliance (as a measure of stiffness) was significantly improved after four weekly administrations of pinocembrin to bleomycin-damaged lung segments. There were significantly lower numbers of neutrophils and inflammatory cells in the bronchoalveolar lavage of bleomycin-infused lung segments that were treated with pinocembrin. Compared to bleomycin damaged lung segments without drug treatment, pinocembrin administration was associated with significantly lower numbers of immuno-positive CD8+ and CD4+ T cells in the lung parenchyma. Histopathology scoring data showed that pinocembrin treatment was associated with significant improvement in inflammation and overall pathology scores. Hydroxy proline analysis showed that the administration of pinocembrin did not reduce the increased collagen content that was induced by bleomycin in this model. Analyses of Masson's Trichrome stained sections showed that pinocembrin treatment significantly reduced the connective tissue content in lung segments exposed to bleomycin when compared to bleomycin-infused lungs that did not receive pinocembrin. The striking anti-inflammatory and modest anti-fibrotic remodelling effects of pinocembrin administration were likely linked to the compound's ability to improve lung pathology and functional compliance in this animal model of pulmonary fibrosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antifibrotic Agents / therapeutic use*
  • Bleomycin / toxicity
  • Bronchoalveolar Lavage Fluid / chemistry
  • Bronchoalveolar Lavage Fluid / immunology
  • CD4-Positive T-Lymphocytes / cytology
  • CD4-Positive T-Lymphocytes / metabolism
  • Disease Models, Animal
  • Eucalyptus / chemistry
  • Eucalyptus / metabolism
  • Flavanones / isolation & purification
  • Flavanones / therapeutic use*
  • Lung / pathology
  • Neutrophils / cytology
  • Neutrophils / metabolism
  • Pulmonary Fibrosis / chemically induced
  • Pulmonary Fibrosis / drug therapy*
  • Pulmonary Fibrosis / pathology
  • Respiratory Function Tests
  • Severity of Illness Index
  • Sheep
  • Treatment Outcome

Substances

  • Antifibrotic Agents
  • Flavanones
  • Bleomycin
  • pinocembrin

Grants and funding

This study was funded by Gretals Australia Pty Ltd. https://www.gretals.com/ AC is the CEO of Gretals Pty Ltd Australia The funder provided support in the form of salary for author AC but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.