Pentoxifylline Regulates Plasminogen Activator Inhibitor-1 Expression and Protein Kinase A Phosphorylation in Radiation-Induced Lung Fibrosis

Prediction of prognostic and immune therapy response in lung adenocarcinoma based on MHC-I-related genes

OBJECTIVES

The study investigated the prognostic and immune predictive potential of major histocompatibility complex class I (MHC-I) in lung adenocarcinoma (LUAD).

MATERIALS AND METHODS

With The Cancer Genome Atlas (TCGA)-LUAD and Gene Expression Omnibus datasets (GSE26939, GSE72094) as the training and validation sets, respectively, we used Cox regression analysis to construct a prognostic model, and verified independence of riskscore. The predictive capacity of the model was assessed in both sets using the receiver operating characteristic curve and Kaplan-Meier survival curves. Immune analysis was performed by using ssGSEA. Additionally, immune checkpoint blockade therapy was assessed by using immunophenoscore, Tumor Immune Dysfunction and Exclusion score. Based on the cMAP database, effective small molecule compounds were predicted.

RESULTS

A prognostic model was established based on 8 MHC-I-related genes, and the predictive capacity of the model was accurate. Immune analysis results revealed that patients classified as high-risk had lower levels of immune cell infiltration and impaired immune function. The low-risk group possessed a better response to immune checkpoint blockade therapy. Theobromine and pravastatin were identified as having great potential in improving the prognosis of LUAD.

CONCLUSION

Overall, the study revealed MHC-I-related molecular prognostic biomarkers as robust indicators for LUAD prognosis and immune therapy response.

Tolerogenic dendritic cells in radiation-induced lung injury

Radiation-induced lung injury is a common complication associated with radiotherapy. It is characterized by early-stage radiation pneumonia and subsequent radiation pulmonary fibrosis. However, there is currently a lack of effective therapeutic strategies for radiation-induced lung injury. Recent studies have shown that tolerogenic dendritic cells interact with regulatory T cells and/or regulatory B cells to stimulate the production of immunosuppressive molecules, control inflammation, and prevent overimmunity. This highlights a potential new therapeutic activity of tolerogenic dendritic cells in managing radiation-induced lung injury. In this review, we aim to provide a comprehensive overview of tolerogenic dendritic cells in the context of radiation-induced lung injury, which will be valuable for researchers in this field.

Cellular Senescence: A Troy Horse in Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a chronic interstitial lung disease characterized by myofibroblast abnormal activation and extracellular matrix deposition. However, the pathogenesis of PF remains unclear, and treatment options are limited. Epidemiological studies have shown that the average age of PF patients is estimated to be over 65 years, and the incidence of the disease increases with age. Therefore, PF is considered an age-related disease. A preliminary study on PF patients demonstrated that the combination therapy of the anti-senescence drugs dasatinib and quercetin improved physical functional indicators. Given the global aging population and the role of cellular senescence in tissue and organ aging, understanding the impact of cellular senescence on PF is of growing interest. This article systematically summarizes the causes and signaling pathways of cellular senescence in PF. It also objectively analyzes the impact of senescence in AECs and fibroblasts on PF development. Furthermore, potential intervention methods targeting cellular senescence in PF treatment are discussed. This review not only provides a strong theoretical foundation for understanding and manipulating cellular senescence, developing new therapies to improve age-related diseases, and extending a healthy lifespan but also offers hope for reversing the toxicity caused by the massive accumulation of senescence cells in humans.

Perspectives of PDE inhibitor on treating idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease (ILD) without an identifiable cause. If not treated after diagnosis, the average life expectancy is 3-5 years. Currently approved drugs for the treatment of IPF are Pirfenidone and Nintedanib, as antifibrotic drugs, which can reduce the decline rate of forced vital capacity (FVC) and reduce the risk of acute exacerbation of IPF. However these drugs can not relieve the symptoms associated with IPF, nor improve the overall survival rate of IPF patients. We need to develop new, safe and effective drugs to treat pulmonary fibrosis. Previous studies have shown that cyclic nucleotides participate in the pathway and play an essential role in the process of pulmonary fibrosis. Phosphodiesterase (PDEs) is involved in cyclic nucleotide metabolism, so PDE inhibitors are candidates for pulmonary fibrosis. This paper reviews the research progress of PDE inhibitors related to pulmonary fibrosis, so as to provide ideas for the development of anti-pulmonary fibrosis drugs.

Pentoxifylline Inhibits Pulmonary Fibrosis by Regulating Cellular Senescence in Mice

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease, and its occurrence and development are mediated by cellular senescence. Drugs targeting senescent cells seem like a promising and efficacious strategy for IPF treatment. Previous studies have illustrated that pentoxifylline (PTX) may play a certain role in inhibiting pulmonary fibrosis and combating cellular senescence. In this study, we demonstrated that PTX administration inhibits pulmonary fibrosis development and cellular senescence in the bleomycin (BLM)-induced IPF mice model. Moreover, the expression levels of fibrosis-related genes and senescence-related genes in mice lung tissue and primary pulmonary fibroblasts illustrated lung fibroblasts' vital role in these two processes. And the curative effect of PTX was completed mainly by acting on lung fibroblasts. Besides, during the whole treatment, delayed initiation or advanced halt of PTX administration would influence its effectiveness in reducing fibrotic and senescent traits in various degrees, and the latter influenced more. We further determined that a long period of PTX administration could bring noticeable benefits to mice in recovering BLM-induced lung fibrosis and suppressing age-associated cellular senescence. Moreover, it was still effective when PTX administration was used to treat senescent human fibroblasts. Thus, our findings manifested that PTX therapy is an efficient remedy for pulmonary fibrosis by suppressing cellular senescence.

Radiation-Induced Fibrosis in Patients with Head and Neck Cancer: A Review of Pathogenesis and Clinical Outcomes

Radiotherapy-related fibrosis remains one of the most challenging treatment related side effects encountered by patients with head and neck cancer. Several established and ongoing novel therapies have been studied with paucity of data in how to best treat these patients. This review aims to provide researchers and health care providers with a comprehensive review on the presentation, etiology, and therapeutic options for this serious condition.

Pentoxifylline as a Potential Adjuvant Therapy for COVID-19: Impeding the Burden of the Cytokine Storm

The outburst of inflammatory response and hypercoagulability are among the factors contributing to increased mortality in severe COVID-19 cases. Pentoxifylline (PTX), a xanthine-derived drug registered for the treatment of vascular claudication, has been reported to display broad-spectrum anti-inflammatory and immunomodulatory properties via adenosine A2A receptor (A2AR)-related mechanisms, in parallel to its rheological actions. Prior studies have indicated the efficacy of PTX in the treatment of various pulmonary diseases, including the management of acute respiratory distress syndrome of infectious causes. Therefore, PTX has been proposed to have potential benefits in the treatment of SARS-CoV-2 symptoms, as well as its complications. The aim of this review is to discuss available knowledge regarding the role of PTX as a complementary therapeutic in SARS-CoV-2.

Phosphodiesterase Inhibitors in Acute Lung Injury: What Are the Perspectives?

Despite progress in understanding the pathophysiology of acute lung damage, currently approved treatment possibilities are limited to lung-protective ventilation, prone positioning, and supportive interventions. Various pharmacological approaches have also been tested, with neuromuscular blockers and corticosteroids considered as the most promising. However, inhibitors of phosphodiesterases (PDEs) also exert a broad spectrum of favorable effects potentially beneficial in acute lung damage. This article reviews pharmacological action and therapeutical potential of nonselective and selective PDE inhibitors and summarizes the results from available studies focused on the use of PDE inhibitors in animal models and clinical studies, including their adverse effects. The data suggest that xanthines as representatives of nonselective PDE inhibitors may reduce acute lung damage, and decrease mortality and length of hospital stay. Various (selective) PDE3, PDE4, and PDE5 inhibitors have also demonstrated stabilization of the pulmonary epithelial-endothelial barrier and reduction the sepsis- and inflammation-increased microvascular permeability, and suppression of the production of inflammatory mediators, which finally resulted in improved oxygenation and ventilatory parameters. However, the current lack of sufficient clinical evidence limits their recommendation for a broader use. A separate chapter focuses on involvement of cyclic adenosine monophosphate (cAMP) and PDE-related changes in its metabolism in association with coronavirus disease 2019 (COVID-19). The chapter illuminates perspectives of the use of PDE inhibitors as an add-on treatment based on actual experimental and clinical trials with preliminary data suggesting their potential benefit.

Repositioning of pentoxifylline as an immunomodulator and regulator of the renin-angiotensin system in the treatment of COVID-19

Pentoxifylline (PTX) is a phosphodiesterase inhibitor that increases cyclic adenosine monophosphate levels, which in turn activate protein kinase, leading to a reduction in the synthesis of proinflammatory cytokines to ultimately influence the renin-angiotensin system (RAS) in vitro by inhibiting angiotensin 1 receptor (AT1R) expression. The rheological, anti-inflammatory, and renin-angiotensin axis properties of PTX highlight this drug as a therapeutic treatment alternative for patients with COVID-19 by helping reduce the production of the inflammatory cytokines without deleterious effects on the immune system to delay viral clearance. Moreover, PTX can restore the balance of the immune response, reduce damage to the endothelium and alveolar epithelial cells, improve circulation, and prevent microvascular thrombosis. There is further evidence that PTX can improve ventilatory parameters. Therefore, we propose repositioning PTX in the treatment of COVID-19. The main advantage of repositioning PTX is that it is an affordable drug that is already available worldwide with an established safety profile, further offering the possibility of immediately analysing the result of its use and associated success rates. Another advantage is that PTX selectively reduces the concentration of TNF-α mRNA in cells, which, in the case of an acute infectious state such as COVID-19, would seem to offer a more strategic approach.

Plasminogen activator inhibitor-1 serves an important role in radiation-induced pulmonary fibrosis

Radiation-induced pulmonary fibrosis is a serious complication. Plasminogen activator inhibitor-1 (PAI-1) has been indicated to be a key factor in the progression of pulmonary fibrosis. In the present study, the effect of PAI-1 deficiency on radiation-induced pulmonary fibrosis was analyzed. Wild-type (WT) and PAI-1-deficient (PAI-1^−/−) mice were treated with thoracic irradiation of 15 Gy to induce pulmonary fibrosis. Analyses of bronchoalveolar lavage (BAL) fluids were performed 0, 4, 12, 18, and 24 weeks after irradiation. The degree of pulmonary fibrosis was assessed according to the histology of lung tissues and hydroxyproline contents. The results demonstrated that the irradiation of WT mice increased PAI-1 expression in the lungs after 18 weeks and established lung fibrosis at 24 weeks. The number of total cells and transforming growth factor-β levels in BAL fluid were significantly lower at 24 weeks after irradiation in PAI-1^−/− mice compared with WT mice. Furthermore, histological examination revealed that the extent of pulmonary fibrosis was attenuated in PAI-1^−/− mice compared with that in WT mice. Hydroxyproline content was also significantly lower in PAI-1^−/− mice compared with WT mice at 24 weeks after irradiation. In conclusion, PAI-1 serves an important role in the development of radiation-induced pulmonary fibrosis and may represent a novel therapeutic target for pulmonary fibrosis.

Irradiated Human Umbilical Vein Endothelial Cells Undergo Endothelial-Mesenchymal Transition via the Snail/miR-199a-5p Axis to Promote the Differentiation of Fibroblasts into Myofibroblasts

Radiation induced pulmonary fibrosis (RIPF) is one of the major side effects of radiotherapy for lung cancer. Previous studies have shown that endothelial cells and activated myofibroblasts play a key role in RIPF. However, the interaction between irradiated endothelial cells and activation of myofibroblasts has not been reported. The aim of the present study was to examine whether irradiated endothelial cells would affect the differentiation of fibroblasts into myofibroblasts in the process of RIPF. In the current study, we used a coculture system that allowed direct contact between human fetal lung fibroblasts (MRC-5) and irradiated human umbilical vein endothelial cells (HUVECs). After 24 or 48 h, cells were sorted by flow cytometry. Radiation induced endothelial-mesenchymal transition (EndMT) by significantly increasing the expression of Snail and vimentin and reducing the expression of CD31 in HUVECs. In addition, irradiation of HUVECs induced the expression of collagen type I and α-smooth muscle actin (α-SMA) in MRC-5 cells. Further investigation indicated that irradiation of HUVECs induced the differentiation of fibroblasts into myofibroblasts through the Snail/miR-199a-5p axis. We conclude that irradiated endothelial cells undergo EndMT to promote differentiation of fibroblasts into myofibroblasts via the Snail/miR-199a-5p axis.