IL-8 concurrently promotes idiopathic pulmonary fibrosis mesenchymal progenitor cell senescence and PD-L1 expression enabling escape from immune cell surveillance

Advances in understanding the role of interleukins in pulmonary fibrosis (Review)

Pulmonary fibrosis (PF) is a progressive, irreversible disease characterized by heterogeneous interstitial lung tissue damage. It originates from persistent or repeated lung epithelial injury and leads to the activation and differentiation of fibroblasts into myofibroblasts. Interleukins (ILs) are a group of lymphokines crucial for immunomodulation that are implicated in the pathogenesis of PF. However, different types of ILs exert disparate effects on PF. In the present review, based on the effect on PF, ILs are classified into three categories: i) Promotors of PF; ii) inhibitors of PF; and iii) those that exert dual effects on PF. Several types of ILs can promote PF by provoking inflammation, initiating proliferation and transdifferentiation of epithelial cells, exacerbating lung injury, while other ILs can inhibit PF through suppressing expression of inflammatory factors, modulating the Th1/Th2 balance and autophagy. The present review summarizes the association of ILs and PF, focusing on the roles and mechanisms of ILs underlying PF.

Biomimetic Topological Micropattern Arrays Regulate the Heterogeneity of Cellular Fates in Lung Fibroblasts between Fibrosis and Invasion

Idiopathic pulmonary fibrosis (IPF) is characterized by persistent tissue injury, dysregulated wound healing, and extracellular matrix (ECM) deposition by myofibroblasts (MFs) through the fibroblast-to-myofibroblast transition (FMT). Implicit in the FMT process are changes in the ECM and cellular topology, but their relationship with the lung fibroblast phenotype has not been explored. We engineered topological mimetics of alignment cues (anisotropy/isotropy) using lung decellularized ECM micropattern arrays and investigated the effects of cellular topology on cellular fates in MRC-5 lung fibroblasts. We found that isotropic MRC-5 cells presented changes of the cytoskeleton, increased cell-cell adhesions and a multicellular architecture with increased overlap, changes in actin-myosin development, and enhanced focal adhesion and cell junction with random alignment. Besides, anisotropic fibroblasts were activated into a regular phenotype with an ECM remodeling profile. In contrast, isotropic fibroblasts developed a highly invasive phenotype expressing molecules, including CD274/programmed death-ligand 1 (PD-L1), cellular communication network factor 2 (CCN2)/connective tissue growth factor (CTGF), hyaluronan synthase 2 (HAS2), and semaphorin 7A (SEMA7A), but with downregulated matrix genes. Moreover, isotropic fibroblasts also showed higher expressions of Ki-67 and cyclin D1 (CCND1), resistance to apoptosis/senescence, and decreased autophagy. The topology regulated the cellular heterogeneity and resulted in positive feedback between changes in the cellular phenotype and the ECM structure, which may aggravate fibrosis and lead to a priming of malignant microenvironment during carcinogenesis. Using the versatile platform of micropattern array, we can not only visualize the interaction mechanism between cells and the ECM but also select potential clinical targets for diagnosis and therapeutics.

Interstitial lung diseases with concomitant lung cancer: a data mining approach revealing a complex condition with gender- and immune-associated specific implications

Background

Interstitial lung diseases (ILDs) comprise a family of heterogeneous entities, primarily characterised by chronic scarring of the lung parenchyma. Among ILDs, idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonitis, associated with progressive functional decline leading to respiratory failure, a high symptom burden, and mortality. Notably, the incidence of lung cancer (LC) in patients already affected by ILDs-mainly IPF-is significantly higher than in the general population. Moreover, these cases are often neglected and deprived of active oncologic treatments.

Methods

We here aim to identify variables predictive of outcome (mortality) in a multicentre retrospective cohort of ILD associated with lung cancer, collected from 2018 to the end of 2023. Overall, 73 cases were identified, and exhaustive clinicopathologic data were available for 55 patients. Among them, 42 had IPF. The entire dataset was then analysed by using the JMP partition algorithm (JMP-Statistical Discoveries, from SAS), which can choose the optimum splits from many possible trees, making it a powerful modelling and data discovery tool.

Results

The average age at lung cancer diagnosis was 71.4 years, whereas the average age at IPF diagnosis was 69.5 years. The average Charlson Comorbidity Index was 4.6. Female patients constituted 28.3% (15) of the evaluated cases. The most frequent tumour histotype was adenocarcinoma (45.2%), and in more than 60% of the cases (67.9%), cancer was diagnosed at an early stage (TNM I-II-IIIA). A significant gender difference emerges regarding the overall patient survival, and quite unexpectedly, surgical approach to IPF-associated LC and the detection of serum autoantibodies are among the strongest outcome predictors.

Conclusions

The analysis performed is descriptive and successfully identifies key features of this specific and rare cancer population. IPF-associated LC emerges as a unique malignant disease defined by specific gender and histopathologic clinical and molecular parameters, which might benefit from active treatments.

The Chemokine System as a Key Regulator of Pulmonary Fibrosis: Converging Pathways in Human Idiopathic Pulmonary Fibrosis (IPF) and the Bleomycin-Induced Lung Fibrosis Model in Mice

Idiopathic pulmonary fibrosis (IPF) is a chronic and lethal interstitial lung disease (ILD) of unknown origin, characterized by limited treatment efficacy and a fibroproliferative nature. It is marked by excessive extracellular matrix deposition in the pulmonary parenchyma, leading to progressive lung volume decline and impaired gas exchange. The chemokine system, a network of proteins involved in cellular communication with diverse biological functions, plays a crucial role in various respiratory diseases. Chemokine receptors trigger the activation, proliferation, and migration of lung-resident cells, including pneumocytes, endothelial cells, alveolar macrophages, and fibroblasts. Around 50 chemokines can potentially interact with 20 receptors, expressed by both leukocytes and non-leukocytes such as tissue parenchyma cells, contributing to processes such as leukocyte mobilization from the bone marrow, recirculation through lymphoid organs, and tissue influx during inflammation or immune response. This narrative review explores the complexity of the chemokine system in the context of IPF and the bleomycin-induced lung fibrosis mouse model. The goal is to identify specific chemokines and receptors as potential therapeutic targets. Recent progress in understanding the role of the chemokine system during IPF, using experimental models and molecular diagnosis, underscores the complex nature of this system in the context of the disease. Despite advances in experimental models and molecular diagnostics, discovering an effective therapy for IPF remains a significant challenge in both medicine and pharmacology. This work delves into microarray results from lung samples of IPF patients and murine samples at different stages of bleomycin-induced pulmonary fibrosis. By discussing common pathways identified in both IPF and the experimental model, we aim to shed light on potential targets for therapeutic intervention. Dysregulation caused by abnormal chemokine levels observed in IPF lungs may activate multiple targets, suggesting that chemokine signaling plays a central role in maintaining or perpetuating lung fibrogenesis. The highlighted chemokine axes (CCL8-CCR2, CCL19/CCL21-CCR7, CXCL9-CXCR3, CCL3/CCL4/CCL5-CCR5, and CCL20-CCR6) present promising opportunities for advancing IPF treatment research and uncovering new pharmacological targets within the chemokine system.

Tumor suppressors RBL1 and PTEN are epigenetically silenced in IPF mesenchymal progenitor cells by a CD44/Brg1/PRMT5 regulatory complex

The idiopathic pulmonary fibrosis (IPF) lung contains mesenchymal progenitor cells (MPCs) that display durable activation of oncogenic signaling and cell-autonomous fibrogenicity in vivo. Prior work identified a CD44/Brg1/PRMT5 nuclear regulatory module in IPF MPCs that increased the expression of genes positively regulating pluripotency and self-renewal. Left unanswered is how IPF MPCs evade negative regulation of self-renewal. Here we sought to identify mechanisms disabling negative regulation of self-renewal in IPF MPCs. We demonstrate that expression of the tumor suppressor genes rbl1 and pten is decreased in IPF MPCs. The mechanism involves the CD44-facilitated association of the chromatin remodeler Brg1 with the histone-modifying methyltransferase PRMT5. Brg1 enhances chromatin accessibility leading to PRMT5-mediated methylation of H3R8 and H4R3 on the rbl1 and pten genes, repressing their expression. Genetic knockdown or pharmacological inhibition of either Brg1 or PRMT5 restored RBL1 and PTEN expression reduced IPF MPC self-renewal in vitro and inhibited IPF MPC-mediated pulmonary fibrosis in vivo. Our studies indicate that the CD44/Brg1/PRMT5 regulatory module not only functions to activate positive regulators of pluripotency and self-renewal but also functions to repress tumor suppressor genes rbl1 and pten. This confers IPF MPCs with the cancer-like property of cell-autonomous self-renewal providing a molecular mechanism for relentless fibrosis progression in IPF.NEW & NOTEWORTHY Here we demonstrate that a CD44/Brg1/PRMT5 epigenetic regulatory module represses the tumor suppressor genes RBL1 and PTEN in IPF mesenchymal progenitor cells, thereby promoting their self-renewal and maintenance of a critical pool of fibrogenic mesenchymal progenitor cells.

Senescence and fibrosis in salivary gland aging and disease

Salivary gland hypofunction is highly prevalent in aged and diseased individuals leading to significant discomfort and morbidity. One factor that contributes to salivary gland hypofunction is cellular aging, or senescence. Senescent cells can impair gland function by secreting paracrine-acting growth factors and cytokines, known as senescence-associated secretory phenotype (SASP) factors. These SASP factors stimulate inflammation, propagate the senescent phenotype through the bystander effect, and stimulate fibrosis. As senotherapeutics that target senescent cells have shown effectiveness in limiting disease manifestations in other conditions, there is interest in the use of these drugs to treat salivary gland hypofunction. In this review, we highlight the contribution of senescence and fibrosis to salivary gland pathologies. We also discuss therapeutic approaches to eliminate or modulate the senescent SASP phenotype for treating age-related salivary gland diseases and extending health span.

Cellular senescence in chronic lung diseases from newborns to the elderly: An update literature review

The role of cellular senescence in age-related diseases has been fully recognized. In various age-related-chronic lung diseases, the function of alveolar epithelial cells (AECs) is impaired and alveolar regeneration disorders, especially in bronchopulmonary dysplasia，pulmonary fibrosis (PF), chronic obstructive pulmonary disease (COPD), cancer, etc. Except for age-related-chronic lung diseases, an increasing number of studies are exploring the role of cellular senescence in developmental chronic lung diseases, which typically originate in childhood and even in the neonatal period. This review provides an overview of cellular senescence and lung diseases from newborns to the elderly, attempting to draw attention to the relationship between cellular senescence and developmental lung diseases.

Inhibitor of PD-1/PD-L1: a new approach may be beneficial for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a globally prevalent, progressive disease with limited treatment options and poor prognosis. Because of its irreversible disease progression, IPF affects the quality and length of life of patients and imposes a significant burden on their families and social healthcare services. The use of the antifibrotic drugs pirfenidone and nintedanib can slow the progression of the disease to some extent, but it does not have a reverse effect on the prognosis. The option of lung transplantion is also limited owing to contraindications to transplantation, possible complications after transplantation, and the risk of death. Therefore, the discovery of new, effective treatment methods is an urgent need. Over recent years, various studies have been undertaken to investigate the relationship between interstitial pneumonia and lung cancer, suggesting that some immune checkpoints in IPF are similar to those in tumors. Immune checkpoints are a class of immunosuppressive molecules that are essential for maintaining autoimmune tolerance and regulating the duration and magnitude of immune responses in peripheral tissues. They can prevent normal tissues from being damaged and destroyed by the immune response. While current studies have focused on PD-1/PD-L1 and CTLA-4, PD-1/PD-L1 may be the only effective immune checkpoint IPF treatment. This review discusses the application of PD-1/PD-L1 checkpoint in IPF, with the aim of finding a new direction for IPF treatment.

Pneumocystis carinii infection drives upregulation of Fn1 expression that causes pulmonary fibrosis with an inflammatory response

BACKGROUND

Pneumocystis carinii is an opportunistic fungal pathogen that may cause pneumonia and lead to pulmonary fibrosis.

AIMS

This study attempted to investigate the role of P. carinii infection-related genes in regulating lung fibrosis in mice.

METHODS

A screening of P. carinii infection-related differential mRNAs was performed using the GEO database, followed by protein-protein interaction (PPI) network construction using the STRING website in order to obtain P. carinii infection-related key genes. The development of a mouse model with gene aberrant expression was achieved by utilizing mice carrying the Cre-LoxP recombinase system. Dexamethasone was employed to induce tracheal infection in order to develop a model of pulmonary fibrosis, and the magnitude of lung injury was assessed by performing hematoxylin-eosin (H&E) staining and Masson staining. Lung coefficient and hydroxyproline level were assessed on sections of lung tissue as well. Finally, the magnitude of lung fibrosis and inflammation in mice was determined based on immunofluorescence and on the expression of genes associated with lung fibrosis and inflammation.

RESULTS

Fn1 was found by PPI with the highest connectivity in the PPI network associated with immunity and inflammation. Besides, Fn1 was significantly highly expressed in P. carinii-infected mice samples. The P carinii pneumonia (PCP)+Fn1fl/fl group had significantly higher lung coefficients, hydroxyproline levels and TNF-α, IL-6, IL-1β, IL-8 and NLRP3 expression levels, and significantly lower IL-10 expression levels. The results found in PCP+SPC-Cre:Fn1fl/fl group were the opposite. The results of the pulmonary fibrosis level study showed that the PCP+Fn1fl/fl group had the most intense H&E and Masson staining, and significantly higher expression levels of Col1A2, Col3A1 and α-SMA, which were lower in the PCP+SPC-Cre:Fn1fl/fl group.

CONCLUSIONS

P. carinii infection may promote the upregulation of Fn1, which causes pulmonary fibrosis with an inflammatory response.

Emerging role of immune cells as drivers of pulmonary fibrosis

The pathogenesis of pulmonary fibrosis, including idiopathic pulmonary fibrosis (IPF) and other forms of interstitial lung disease, involves a complex interplay of various factors including host genetics, environmental pollutants, infection, aberrant repair and dysregulated immune responses. Highly variable clinical outcomes of some ILDs, in particular IPF, have made it difficult to identify the precise mechanisms involved in disease pathogenesis and thus the development of a specific cure or treatment to halt and reverse the decline in patient health. With the advent of in-depth molecular diagnostics, it is becoming evident that the pathogenesis of IPF is unlikely to be the same for all patients and therefore will likely require different treatment approaches. Chronic inflammation is a cardinal feature of IPF and is driven by both innate and adaptive immune responses. Inflammatory cells and activated fibroblasts secrete various pro-inflammatory cytokines and chemokines that perpetuate the inflammatory response and contribute to the recruitment and activation of more immune cells and fibroblasts. The balance between pro-inflammatory and regulatory immune cell subsets, as well as the interactions between immune cell types and resident cells within the lung microenvironment, ultimately determines the extent of fibrosis and the potential for resolution. This review examines the role of the innate and adaptive immune responses in pulmonary fibrosis, with an emphasis on IPF. The role of different immune cell types is discussed as well as novel anti-inflammatory and immunotherapy approaches currently in clinical trial or in preclinical development.

Expression of PD-1/PD-L1 axis in mediastinal lymph nodes and lung tissue of human and experimental lung fibrosis indicates a potential therapeutic target for idiopathic pulmonary fibrosis

BACKGROUND

Mediastinal lymph node enlargement is prevalent in patients with idiopathic pulmonary fibrosis (IPF). Studies investigating whether this phenomenon reflects specific immunologic activation are lacking.

METHODS

Programmed cell death-1 (PD-1)/ programmed cell death ligand-1 (PD-L1) expression in mediastinal lymph nodes and lung tissues was analyzed. PD-1, PD-L1 mRNA expression was measured in tracheobronchial lymph nodes of mice following bleomycin-induced injury on day 14. Finally, the effect of the PD-1 inhibitor, pembrolizumab, in bleomycin-induced pulmonary fibrosis was investigated.

RESULTS

We analyzed mediastinal lymph nodes of thirty-three patients (n = 33, IPF: n = 14, lung cancer: n = 10, concomitant IPF and lung cancer: n = 9) and lung tissues of two hundred nineteen patients (n = 219, IPF: 123, controls: 96). PD-1 expression was increased, while PD-L1 expression was decreased, in mediastinal lymph nodes of patients with IPF compared to lung cancer and in IPF lungs compared to control lungs. Tracheobronchial lymph nodes isolated on day 14 from bleomycin-treated mice exhibited increased size and higher PD-1, PD-L1 mRNA levels compared to saline-treated animals. Pembrolizumab blunted bleomycin-induced lung fibrosis, as indicated by reduction in Ashcroft score and improvement in respiratory mechanics.

CONCLUSIONS

Mediastinal lymph nodes of patients with IPF exhibit differential expression profiles than those of patients with lung cancer indicating distinct immune-mediated pathways regulating fibrogenesis and carcinogenesis. PD-1 expression in mediastinal lymph nodes is in line with lung tissue expression. Lower doses of pembrolizumab might exert antifibrotic effects. Clinical trials aiming to endotype patients based on mediastinal lymph node profiling and accordingly implement targeted therapies such as PD-1 inhibitors are greatly anticipated.