Anti-asialo GM1 NK cell depleting antibody does not alter the development of bleomycin induced pulmonary fibrosis.

Justin Monnier,Brian A Zabel,Bernhard Ryffel

doi:10.1371/journal.pone.0099350

Justin Monnier, Brian A Zabel + Show 1 more

Open Access

https://doi.org/10.1371/journal.pone.0099350

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Abstract

Despite circumstantial evidence postulating a protective role for NK cells in many fibrotic conditions, their contribution to the development of pulmonary fibrosis has yet to be tested. Lung-migrating NK cells are thought to attenuate the development of bleomycin induced pulmonary fibrosis (BIPF) by providing anti-fibrotic mediators and cytokines, such as IFN-γ. If true, we reasoned that depletion of NK cells during experimentally-induced fibrotic disease would lead to exacerbated fibrosis. To test this, we treated mice with NK cell-depleting antisera (anti-asialo GM1) and evaluated lung inflammation and fibrosis in the BIPF model. While NK cell infiltration into the airways was maximal at day 10 after bleomycin injection, NK cells represented a minor portion (1–3%) of the total leukocytes in BAL fluid. Anti-asialo GM1 significantly abrogated NK cell numbers over the course of the disease. Depletion of NK cells with anti-asialo GM1 before and throughout the BIPF model, or during just the fibrotic phase did not alter fibrosis development or affect the levels of any of the pro-inflammatory/pro-fibrotic cytokines measured (IL-1β, IL-17, IFN-γ, TGF-β and TNF-α). In addition, adoptively transferred NK cells, which were detectable systemically and in the airways throughout BIPF, failed to impact lung fibrosis. These findings indicate that NK cells likely do not play an essential protective role in controlling pulmonary fibrosis development.

Highlights

Pulmonary fibrosis is a progressive lung disease characterized by the irreversible formation of scar tissue throughout the lungs, which leads to respiratory failure [1,2,3]
NK cells represent a small portion of the total leukocytes in Bronchoalveolar Lavage (BAL) fluid Leukocyte subsets infiltrated the bronchoalveolar space at different rates and magnitudes during bleomycin induced pulmonary fibrosis (BIPF)
This is the first study to our knowledge that has investigated the use of anti-asialo GM1 in depleting NK cells during BIPF

Summary

Introduction

Pulmonary fibrosis is a progressive lung disease characterized by the irreversible formation of scar tissue throughout the lungs, which leads to respiratory failure [1,2,3]. Much of our understanding of the molecular and cellular mechanisms governing pulmonary fibrosis is derived from in vivo mouse studies using the BIPF model, in which lung fibrosis is induced with a single administration of bleomycin [4]. As a result the list of leukocytes (neutrophils, lymphocytes, macrophages, eosinophils) and secreted cytokines and growth factors (TGF-b, PDGF, TNF-a, IFN-c, IL-17, IL-1, IL-13...) involved in the progression of pulmonary fibrosis is extensive [5]. NK cells are thought to provide protection against bleomycin induced injury through the production IFN-c, which is believed to counteract the profibrotic activities of TGF-b [6,9,10]

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