Fibroblasts From Idiopathic Pulmonary Fibrosis Induce Apoptosis and Reduce the Migration Capacity of T Lymphocytes.

Leslie Chavez-Galan,José Cisneros,Ivette Buendía-Roldán,Andy Ruiz,Moisés Selman,Martha Montaño,Carlos Ramos,Lucero A Ramon-Luing,Annie Pardo,Alfonso Salgado,Carina Becerril

doi:10.3389/fimmu.2022.820347

Abstract

Idiopathic pulmonary fibrosis (IPF) is a progressive and irreversible lung disease of unknown etiology. Myofibroblasts are organized in peculiar subepithelial fibroblasts foci (FF), where they abnormally persist and exclude lymphocytes by unclear mechanisms. FF are the source of an excessive extracellular matrix, which results in progressive stiffening and destruction of the lung architecture. We hypothesized that the absence of T cells inside the FF could be related, at least partially, to an inefficient function of lymphocytes induced by IPF fibroblasts. Here, we evaluated the effect of a supernatant from IPF fibroblasts on T-cell apoptosis and migration capacity. Data showed that IPF fibroblasts secrete pro-apoptotic molecules (both from extrinsic and intrinsic pathways), generating a microenvironment that induces apoptosis of T cells at 3 h of culture, despite a weak anti-apoptotic profile exhibited by these T cells. At 24 h of culture, the supernatants from both IPF and control fibroblasts provoked T-cell death. However, at this time of culture, IPF fibroblasts caused a marked decrease in T-cell migration; in contrast, control lung fibroblasts induced an increase of T-cell migration. The reduction of T-cell migratory capacity provoked by IPF fibroblasts was associated with a negative regulation of RHOA and ROCK, two essential GTPases for migration, and was independent of the expression of chemokine receptors. In conclusion, our findings demonstrate that IPF fibroblasts/myofibroblasts induce apoptosis and affect T-cell migration, revealing a mechanism involved in the virtual absence of T lymphocytes inside the FF.

Highlights

Idiopathic pulmonary fibrosis (IPF) is a specific form of chronic, progressive, fibrosing interstitial pneumonia of unknown etiology that occurs primarily in older adults, and is characterized by the histopathologic and/or radiologic pattern of usual interstitial pneumonia (UIP) [1, 2]
We assessed early and late apoptosis and necrosis of T cells from healthy donors, cultured during 3 and 24 h with IPF (SN) or CLF (SN), media alone was used as a negative control
Gates of CD4+ T cells and CD8+ T cells were delimited (Figure S1B), and cell death was analyzed in a dot plot color where Annexin-V+ cells indicated early apoptosis (EApop), Annexin-V+7-AAD+ late apoptosis (L-Apop), and 7AAD+ necrotic cells (Nec) (Figure 2A)

Summary

Introduction

Idiopathic pulmonary fibrosis (IPF) is a specific form of chronic, progressive, fibrosing interstitial pneumonia of unknown etiology that occurs primarily in older adults, and is characterized by the histopathologic and/or radiologic pattern of usual interstitial pneumonia (UIP) [1, 2]. The pathogenic mechanisms are uncertain, but strong evidence indicates that the early and critical event is the aberrant activation of lung epithelial cells which undergo strong phenotypic and functional changes inducing a progressive and multistep process that involves fibroblast activation, extracellular matrix remodeling, and the fibrotic destruction of the lung architecture [2–5]. In this sequence, IPF fibroblasts undergo strong activation and transdifferentiate in myofibroblasts leading to a chaotic production of large amounts of extracellular matrix components mainly fibrillar collagens [2, 3, 5, 6]. In fibroblasts from Masson bodies in organizing pneumonia, an intra-alveolar structure similar to FF usually resolves almost completely, and fibroblasts are eliminated by increased apoptotic activity [13]

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Conclusion