Beneficial impact of cathelicidin on hypersensitivity pneumonitis treatment-In vivo studies.

Claudia Staab-Weijnitz,Marta Kinga Lemieszek,Marcin Golec,Janusz Milanowski,Katarzyna Sawa-Wejksza,Jacek Zwoliński,Jacek Dutkiewicz

doi:10.1371/journal.pone.0251237

Abstract

Cathelicidin (CRAMP) is a defence peptide with a wide range of biological responses including antimicrobial, immunomodulatory and wound healing. Due to its original properties the usefulness of CRAMP in the treatment of pulmonary fibrosis was assessed in a murine model of hypersensitivity pneumonitis (HP). The studies were conducted on mouse strain C57BL/6J exposed to a saline extract of Pantoea agglomerans cells (HP inducer). Cathelicidin was administered in the form of an aerosol during and after HP development. Changes in the composition of immune cell populations (NK cells, macrophages, lymphocytes: Tc, Th, Treg, B), were monitored in lung tissue by flow cytometry. Extracellular matrix deposition (collagens, hydroxyproline), the concentration of cytokines involved in inflammatory and the fibrosis process (IFNγ, TNFα, TGFβ1, IL1β, IL4, IL5, IL10, IL12α, IL13) were examined in lung homogenates by the ELISA method. Alterations in lung tissue morphology were examined in mouse lung sections stained with haematoxylin and eosin as well as Masson trichrome dyes. The performed studies revealed that cathelicidin did not cause any negative changes in lung morphology/structure, immune cell composition or cytokines production. At the same time, CRAMP attenuated the immune reaction induced by mice chronic exposure to P. agglomerans and inhibited hydroxyproline and collagen deposition in the lung tissue of mice treated with bacteria extract. The beneficial effect of CRAMP on HP treatment was associated with restoring the balance in quantity of immune cells, cytokines production and synthesis of extracellular matrix components. The presented study suggests the usefulness of cathelicidin in preventing lung fibrosis; however, cathelicidin was not able to reverse pathological changes completely.

Highlights

Linear regression analysis of CRAMP concentration in response to synthetic cathelicidin inhalation revealed that doubling the physiological concentration of cathelicidin in the lung tissue (1.106 μg/ml) requires the administration to mice in a single inhalation of 1.2 μg of synthetic defence peptide
A significant accumulation of Natural Killer (NK) cells was observed in lung tissues collected from animals treated with CRAMP for 28 days
Additional studies conducted in the Hypersensitivity pneumonitis (HP) model revealed both significant down-regulation of CRAMP gene expression (Fold Change = - 2.28) and a decrease of cathelicidin concentration (Fold Change = - 1.66) in mouse lungs collected after 28 days of exposure to P. agglomerans, compared to untreated mice [20]

Summary

Introduction

Hypersensitivity pneumonitis (HP), or extrinsic allergic alveolitis, is an interstitial lung disease induced by chronic exposure to organic dust (particles of plants, animals, fungi, or bacteria). Cathelicidin in hypersensitivity pneumonitis treatment received remuneration from the grant implementation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding was received for this study

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