C-X-C-Chemokine-Receptor-Type-4 Inhibitor AMD3100 Attenuates Pulmonary Inflammation and Fibrosis in Silicotic Mice

Global scenario of silica-associated diseases: A review on emerging pathophysiology of silicosis and potential therapeutic regimes

Silicosis is an occupational fibrotic lung disease caused by exposure to respirable crystalline silica dust particles produced during industrial activities. Other crystalline silica-induced pulmonary disorders include a predisposition to mycobacterial infections, obstructive airway diseases, idiopathic pulmonary fibrosis, and lung cancer. This review paper discusses the burden of silicosis and associated co-morbidities in developed as well as developing countries globally using the published data of various government agencies, related organizations, and epidemiological findings. Moreover, it sheds light on diverse mechanisms of silicosis, outlining molecular events and peculiar alterations in lung parenchyma leading to this occupational lung disease. Evaluation of pathophysiological mechanisms could aid in the identification of novel target molecules and treatments; to date, there is no curative treatment for silicosis. In recent periods, a lot of attention has been focused on the development and fabrication of suitable nanocarriers for improved and sustained drug delivery in the pulmonary system. Nanoparticle-based therapeutic modality has been evaluated in in-vitro and ex-vivo silicosis models for prolongation of drug activity and improved therapeutic outcomes. The preclinical findings open the doors to clinical trials for operational and regenerative nanoformulations, which eventually create a positive change in medical practice. The following review summarizes various therapeutic approaches available and in the pipe line for silicosis and also stresses the preventive practices for effectively combating this occupational hazard.

Crystalline silica on the lung-environment interface: Impact on immunity, epithelial cells, and therapeutic perspectives for autoimmunity

Crystalline silica (the most abundant form of silicon dioxide) is a natural element that is ubiquitous in the Earth's crust. Chronic personal or professional exposure has been implicated in various pathologies, including silicosis and autoimmune diseases since the early 20th century. More recently, a specific pathogenic role for crystalline silica has been identified through its impact on lung epithelial cells as well as immune cells present at this organism barrier. This review summarizes the current in vitro and in vivo knowledge regarding the physiopathology of crystalline silica at the lung-environment interface, discusses its effects on innate and adaptive immune cells and epithelial cells, and reviews current therapeutic perspectives explored in mouse models to alleviate its impact, especially on autoimmune phenotypes.

Evaluation and the mechanism of ShengXian and JinShuiLiuJun decoction in the treatment of silicotic fibrosis: An integrated network pharmacology, life omics, and experimental validation study

BACKGROUND

Silicosis is a systemic disease characterized by extensive fibrosis due to prolonged exposure to silica dust, with rising incidence rates significantly impacting global public health. ShengXian and JinShuiLiuJun Decoction (SXD) is a Chinese medicinal preparation containing a variety of medicinal plants. It has shown notable clinical efficacy in treating silicotic fibrosis in China. However, the precise mechanisms underlying its therapeutic effects remain unclear. This study integrates network pharmacology, multi-omics analysis, and experimental validation to investigate the potential mechanisms by which SXD treats silicotic fibrosis.

OBJECTIVE

The study aims to investigate the therapeutic efficacy of SXD in treating silicotic fibrosis and to elucidate its underlying molecular mechanisms.

METHODS

HPLC-Q-TOF-MS was used to identify the active components of SXD, and combined with network pharmacology, metabolomics, and transcriptomics, the mechanism of SXD in treating silicotic fibrosis was explored from multiple perspectives. The therapeutic effect of SXD was assessed through HE staining, Masson staining, Micro CT imaging, pulmonary function tests, and hydroxyproline content in lung tissue. Finally, network pharmacology and multi-omics findings were validated using molecular docking. CETSA, immunofluorescence, SPR, and Western blotting were used to analyze key factors in the NF-κB pathway at the animal, cellular, and molecular levels.

RESULTS

SXD treatment improved lung function in silicosis rats, reduced inflammatory cell infiltration, collagen deposition, fibrosis and other pathological changes, and inhibited the protein expression of TNF-α, IL-17A, and IL-1β, and NF-κB in lung tissue. HPLC-Q-TOF-MS combined with network pharmacology identified key compounds such as Liquiritigenin, 3-Methoxynobiletin, Isomangiferin, Hesperidin, shogaol, and Ligustroflavone, which likely exert therapeutic effects through the TNF, IL-17, NF-κB, and TGF-β signaling pathways. Transcriptomics and metabolomics results revealed that SXD up-regulated the expression of NF-κB pathway-related genes (NFKBIA, NFKBIZ) and key regulators of the retinol metabolism pathway, while down-regulating pro-inflammatory genes (IL1B, IL17A, IL6). Experimental findings confirmed that SXD suppressed the expression of NF-κB pathway-related proteins and upstream activators TNF-α, IL-17A, and IL-1β, as well as their receptors, in both lung tissue and cellular models. Additionally, SXD-containing serum had a direct, non-toxic effect on MRC-5 cells, effectively inhibiting collagen expression and TGF-β secretion. SXD also had a positive effect on collagen production and extracellular matrix (ECM) aggregation in fibroblasts. Molecular dynamics studies showed that SXD directly binds to NF-κB and IκB.

CONCLUSION

SXD exerts therapeutic effects on silicotic fibrosis by inhibiting NF-κB signaling transduction mediated by TNF-α, IL-17A, and IL-1β, and suppressing fibroblast activation.

The Importance of Lung Innate Immunity During Health and Disease

The lung is a vital organ for the body as the main source of oxygen input. Importantly, it is also an internal organ that has direct contact with the outside world. Innate immunity is a vital protective system in various organs, whereas, in the case of the lung, it helps maintain a healthy, functioning cellular and molecular environment and prevents any overt damage caused by pathogens or other inflammatory processes. Disturbances in lung innate immunity properties and processes, whether over-responsiveness of the process triggered by innate immunity or lack of responses due to dysfunctions in the immune cells that make up the innate immunity system of the lung, could be correlated to various pathological conditions. In this review, we discuss globally how the components of lung innate immunity are important not only for maintaining lung homeostasis but also during the pathophysiology of notable lung diseases beyond acute pulmonary infections, including chronic obstructive pulmonary disease (COPD), asthma, and pulmonary fibrosis.

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.

Blocking CTLA-4 promotes pressure overload-induced heart failure via activating Th17 cells

Targeting cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) with specific antibody offers long-term benefits for cancer immunotherapy but can cause severe adverse effects in the heart. This study aimed to investigate the role of anti-CTLA-4 antibody in pressure overload-induced cardiac remodeling and dysfunction. Transverse aortic constriction (TAC) was used to induce cardiac hypertrophy and heart failure in mice. Two weeks after the TAC treatment, mice received anti-CTLA-4 antibody injection twice a week at a dose of 10 mg/kg body weight. The administration of anti-CTLA-4 antibody exacerbated TAC-induced decline in cardiac function, intensifying myocardial hypertrophy and fibrosis. Further investigation revealed that anti-CTLA-4 antibody significantly elevated systemic inflammatory factors levels and facilitated the differentiation of T helper 17 (Th17) cells in the peripheral blood of TAC-treated mice. Importantly, anti-CTLA-4 mediated differentiation of Th17 cells and hypertrophic phenotype in TAC mice were dramatically alleviated by the inhibition of interleukin-17A (IL-17A) by an anti-IL-17A antibody. Furthermore, the C-X-C motif chemokine receptor 4 (CXCR4) antagonist AMD3100, also reversed anti-CTLA-4-mediated cardiotoxicity in TAC mice. Overall, these results suggest that the administration of anti-CTLA-4 antibody exacerbates pressure overload-induced heart failure by activating and promoting the differentiation of Th17 cells. Targeting the CXCR4/Th17/IL-17A axis could be a potential therapeutic strategy for mitigating immune checkpoint inhibitors-induced cardiotoxicity.

CXCR4/CXCL12 axis: "old" pathway as "novel" target for anti-inflammatory drug discovery

Inflammation is the body's defense response to exogenous or endogenous stimuli, involving complex regulatory mechanisms. Discovering anti-inflammatory drugs with both effectiveness and long-term use safety is still the direction of researchers' efforts. The inflammatory pathway was initially identified to be involved in tumor metastasis and HIV infection. However, research in recent years has proved that the CXC chemokine receptor type 4 (CXCR4)/CXC motif chemokine ligand 12 (CXCL12) axis plays a critical role in the upstream of the inflammatory pathway due to its chemotaxis to inflammatory cells. Blocking the chemotaxis of inflammatory cells by CXCL12 at the inflammatory site may block and alleviate the inflammatory response. Therefore, developing CXCR4 antagonists has become a novel strategy for anti-inflammatory therapy. This review aimed to systematically summarize and analyze the mechanisms of action of the CXCR4/CXCL12 axis in more than 20 inflammatory diseases, highlighting its crucial role in inflammation. Additionally, the anti-inflammatory activities of CXCR4 antagonists were discussed. The findings might help generate new perspectives for developing anti-inflammatory drugs targeting the CXCR4/CXCL12 axis.

2-Deoxy-D-glucose ameliorates inflammation and fibrosis in a silicosis mouse model by inhibiting hypoxia-inducible factor-1α in alveolar macrophages

Inhaling silica causes the occupational illness silicosis, which mostly results in the gradual fibrosis of lung tissue. Previous research has demonstrated that hypoxia-inducible factor-1α (HIF-1α) and glycolysis-related genes are up-regulated in silicosis. The role of 2-deoxy-D-glucose (2-DG) as an inhibitor of glycolysis in silicosis mouse models and its molecular mechanisms remain unclear. Therefore, we used 2-DG to observe its effect on pulmonary inflammation and fibrosis in a silicosis mouse model. Furthermore, in vitro cell experiments were conducted to explore the specific mechanisms of HIF-1α. Our study found that 2-DG down-regulated HIF-1α levels in alveolar macrophages induced by silica exposure and reduced the interleukin-1β (IL-1β) level in pulmonary inflammation. Additionally, 2-DG reduced silica-induced pulmonary fibrosis. From these findings, we hypothesize that 2-DG reduced glucose transporter 1 (GLUT1) expression by inhibiting glycolysis, which inhibits the expression of HIF-1α and ultimately reduces transcription of the inflammatory cytokine, IL-1β, thus alleviating lung damage. Therefore, we elucidated the important regulatory role of HIF-1α in an experimental silicosis model and the potential defense mechanisms of 2-DG. These results provide a possible effective strategy for 2-DG in the treatment of silicosis.