Safer approaches to therapeutic modulation of TGF-β signaling for respiratory disease

Multifaceted TGF-β signaling, a master regulator: From bench-to-bedside, intricacies, and complexities

Physiological embryogenesis and adult tissue homeostasis are regulated by transforming growth factor-β (TGF-β), an evolutionarily conserved family of secreted polypeptide factors, acting in an autocrine and paracrine manner. The role of TGF-β in inflammation, fibrosis, and cancer is complex and sometimes even contradictory, exhibiting either inhibitory or promoting effects depending on the stage of the disease. Under pathological conditions, especially fibrosis and cancer, overexpressed TGF-β causes extracellular matrix deposition, epithelial-mesenchymal transition, cancer-associated fibroblast formation, and/or angiogenesis. In this review article, we have tried to dive deep into the mechanism of action of TGF-β in inflammation, fibrosis, and carcinogenesis. As TGF-β and its downstream signaling mechanism are implicated in fibrosis and carcinogenesis blocking this signaling mechanism appears to be a promising avenue. However, targeting TGF-β carries substantial risk as this pathway is implicated in multiple homeostatic processes and is also known to have tumor-suppressor functions. There is a need for careful dosing of TGF-β drugs for therapeutic use and patient selection.

Phytochemicals as treatment for allergic asthma: Therapeutic effects and mechanisms of action

BACKGROUND

Allergic asthma is an inflammatory disease caused by the immune system's reaction to allergens, inflammation and narrowing of the airways, and the production of more than normal mucus. One of the main reasons is an increased production of inflammatory cytokines in the lungs that leads to the appearance of symptoms of asthma, including inflammation and shortness of breath. On the other hand, it has been proven that phytochemicals with their antioxidant and anti-inflammatory properties can be useful in improving allergic asthma.

PURPOSE

Common chemical treatments for allergic asthma include corticosteroids, which have many side effects and temporarily relieve symptoms but are not a cure. Therefore, taking the help of natural compounds to improve the quality of life of asthmatic patients can be a valuable issue that has been evaluated in the present review.

STUDY DESIGN AND METHODS

In this study, three databases (Scopus, PubMed, and Cochrane) with the keywords: allergic asthma, phytochemical, plant, and herb were evaluated. The primary result was 5307 articles. Non-English, repetitive, and review articles were deleted from the study.

RESULTS AND DISCUSSION

Finally, after carefully reading the articles, 102 were included in the study (2006-2022). The results of this review state that phytochemicals suppress the inflammatory pathways via inhibition of inflammatory cytokines production/secretion, genes, and proteins involved in the inflammation process, reducing oxidative stress indicators and symptoms of allergic asthma, such as cough and mucus production in the lungs.

CONCLUSION

With their antioxidant effects, this study concluded that phytochemicals suppress cytokines and other inflammatory indicators and thus can be considered an adjunctive treatment for improving allergic asthma.

TGF-β as a therapeutic target in the infarcted and failing heart: cellular mechanisms, challenges, and opportunities

INTRODUCTION

Myocardial fibrosis accompanies most cardiac conditions and can be reparative or maladaptive. Transforming Growth Factor (TGF)-β is a potent fibrogenic mediator, involved in repair, remodeling, and fibrosis of the injured heart.

AREAS COVERED

This review manuscript discusses the role of TGF-β in heart failure focusing on cellular mechanisms and therapeutic implications. TGF-β is activated in infarcted, remodeling and failing hearts. In addition to its fibrogenic actions, TGF-β has a broad range of effects on cardiomyocytes, immune, and vascular cells that may have both protective and detrimental consequences. TGF-β-mediated effects on macrophages promote anti-inflammatory transition, whereas actions on fibroblasts mediate reparative scar formation and effects on pericytes are involved in maturation of infarct neovessels. On the other hand, TGF-β actions on cardiomyocytes promote adverse remodeling, and prolonged activation of TGF-β signaling in fibroblasts stimulates progression of fibrosis and heart failure.

EXPERT OPINION

Understanding of the cell-specific actions of TGF-β is necessary to design therapeutic strategies in patients with myocardial disease. Moreover, to implement therapeutic interventions in the heterogeneous population of heart failure patients, mechanism-driven classification of both HFrEF and HFpEF patients is needed. Heart failure patients with prolonged or overactive fibrogenic TGF-β responses may benefit from cautious TGF-β inhibition.

Exploration of the Pathogenesis of Chronic Obstructive Pulmonary Disease Caused by Smoking-Based on Bioinformatics Analysis and In Vitro Experimental Evidence

This study was aimed at investigating the pathogenesis of chronic obstructive pulmonary disease (COPD) caused by smoking-based on bioinformatics analysis and in vitro experimental evidence. The GEO, GEO2R, TargetScan, miRDB, miRWalk, DAVID, and STRING databases were used for bioinformatics analysis. The mRNA expression and the protein levels were determined by real-time PCR and ELISA. After taking the intersection of the diversified results of the databases, four differentially expressed miRNAs (hsa-miR-146a, hsa-miR-708, hsa-miR-150, and hsa-miR-454) were screened out. Subsequently, a total of 57 target genes of the selected miRNAs were obtained. The results of DAVID analysis showed that the selected miRNAs participated in COPD pathogenesis through long-term potentiation, the TGF-β signaling pathway, the PI3K-Akt signaling pathway, etc. The results of STRING prediction showed that TP53, EP300, and MAPK1 were the key nodes of the PPI network. The results of the confirmatory experiment showed that, compared with the control group, the mRNA expression of ZEB1, MAPK1, EP300, and SP1 were up-regulated, while the expression of MYB was down-regulated and the protein levels of ZEB1, MAPK1, and EP300 were increased. Taken together, miRNAs (hsa-miR-146a, hsa-miR-708, hsa-miR-150, and hsa-miR-454) and their regulated target genes and downstream protein molecules (ZEB1, EP300, and MAPK1) may be closely related to the pathological process of COPD.

Targeting cluster of differentiation 26 / dipeptidyl peptidase 4 (CD26/DPP4) in organ fibrosis

Cluster of differentiation 26 (CD26)/dipeptidyl peptidase 4 (DPP4) is an exopeptidase that is expressed as a transmembrane protein in many organs but also present in a circulating soluble form. Beyond its enzymatic and costimulatory activity, CD26/DPP4 is involved in the pathogenesis of chronic fibrotic diseases across many organ types, such as liver cirrhosis, kidney fibrosis and lung fibrosis. Organ fibrosis is associated with a high morbidity and mortality, and there are no causative therapies that can effectively attenuate the progress of the disease. Growing evidence suggests that inhibiting CD26/DPP4 can modulate the profibrotic tissue microenvironment and thus reduce fibrotic changes within affected organs. This review summarizes the role of CD26/DPP4 in fibroproliferative disorders and highlights new opportunities for an antifibrotic treatment by CD26/DPP4 inhibition. As a major advantage, CD26/DPP4 inhibitors have been in safe and routine clinical use in type 2 diabetes for many years and thus qualify for repurposing to repurpose as a promising therapeutic against fibrosis. LINKED ARTICLES: This article is part of a themed issue on Translational Advances in Fibrosis as a Therapeutic Target. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.22/issuetoc.

Targeting STING-mediated pro-inflammatory and pro-fibrotic effects of alveolar macrophages and fibroblasts blunts silicosis caused by silica particles

Silica is utilized extensively in industrial and commercial applications as a chemical raw material, increasing its exposure and hazardous potential to populations, with silicosis serving as an important representative. Silicosis is characterized by persistent lung inflammation and fibrosis, for which the underlying pathogenesis of silicosis is unclear. Studies have shown that the stimulating interferon gene (STING) participates in various inflammatory and fibrotic lesions. Therefore, we speculated that STING might also play a key role in silicosis. Here we found that silica particles drove the double-stranded DNA (dsDNA) release to activate the STING signal pathway, contributing to alveolar macrophages (AMs) polarization by secreting diverse cytokines. Then, multiple cytokines could generate a micro-environment to exacerbate inflammation and promote the activation of lung fibroblasts, hastening fibrosis. Intriguingly, STING was also crucial for the fibrotic effects induced by lung fibroblasts. Loss of STING could effectively inhibit silica particles-induced pro-inflammatory and pro-fibrotic effects by regulating macrophages polarization and lung fibroblasts activation to alleviate silicosis. Collectively, our results have revealed a novel pathogenesis of silica particles-caused silicosis mediated by the STING signal pathway, indicating that STING may be regarded as a promising therapeutic target in the treatment of silicosis.

Shark VNAR phage display libraries: An alternative source for therapeutic and diagnostic recombinant antibody fragments

The development of recombinant antibody fragments as promising alternatives to full-length immunoglobulins offers vast opportunities for biomedicine. Antibody fragments have important advantages compared with conventional monoclonal antibodies that make them attractive for the biotech industry: superior stability and solubility, reduced immunogenicity, higher specificity and affinity, capacity to target the hidden epitope and cross the blood-brain barrier, the ability to refold after heat denaturation and inexpensive and easy large-scale production. Different antibody formats such as antigen-binding fragments (Fab), single-chain fragment variable (scFv) consisting of the antigen-binding domains of Ig heavy (VH) and light (VL) chain regions connected by a flexible peptide linker, single-domain antibody fragments (sdAbs) like camelid heavy-chain variable domains (VHHs) and shark variable new antigen receptor (VNARs), and bispecific antibodies (bsAbs) are currently being evaluated as diagnostics or therapeutics in preclinical studies and clinical trials. In the present review, we summarize and discuss studies on VNARs, the smallest recombinant antibody fragment, obtained after the screening of different types of phage display antibody libraries. Results published until March 2023 are discussed.

TGF-beta signal transduction: biology, function and therapy for diseases

The transforming growth factor beta (TGF-β) is a crucial cytokine that get increasing concern in recent years to treat human diseases. This signal controls multiple cellular responses during embryonic development and tissue homeostasis through canonical and/or noncanonical signaling pathways. Dysregulated TGF-β signal plays an essential role in contributing to fibrosis via promoting the extracellular matrix deposition, and tumor progression via inducing the epithelial-to-mesenchymal transition, immunosuppression, and neovascularization at the advanced stage of cancer. Besides, the dysregulation of TGF-beta signal also involves in other human diseases including anemia, inflammatory disease, wound healing and cardiovascular disease et al. Therefore, this signal is proposed to be a promising therapeutic target in these diseases. Recently, multiple strategies targeting TGF-β signals including neutralizing antibodies, ligand traps, small-molecule receptor kinase inhibitors targeting ligand-receptor signaling pathways, antisense oligonucleotides to disrupt the production of TGF-β at the transcriptional level, and vaccine are under evaluation of safety and efficacy for the forementioned diseases in clinical trials. Here, in this review, we firstly summarized the biology and function of TGF-β in physiological and pathological conditions, elaborated TGF-β associated signal transduction. And then, we analyzed the current advances in preclinical studies and clinical strategies targeting TGF-β signal transduction to treat diseases.

Specific epigenetic regulators serve as potential therapeutic targets in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF), a disorder observed mostly in older human beings, is characterised by chronic and progressive lung scarring leading to an irreversible decline in lung function. This health condition has a dismal prognosis and the currently available drugs only delay but fail to reverse the progression of lung damage. Consequently, it becomes imperative to discover improved therapeutic compounds and their cellular targets to cure IPF. In this regard, a number of recent studies have targeted the epigenetic regulation by histone deacetylases (HDACs) to develop and categorise antifibrotic drugs for lungs. Therefore, this review focuses on how aberrant expression or activity of Classes I, II and III HDACs alter TGF-β signalling to promote events such as epithelial-mesenchymal transition, differentiation of activated fibroblasts into myofibroblasts, and excess deposition of the extracellular matrix to propel lung fibrosis. Further, this study describes how certain chemical compounds or dietary changes modulate dysregulated HDACs to attenuate five faulty TGF-β-dependent profibrotic processes, both in animal models and cell lines replicating IPF, thereby identifying promising means to treat this lung disorder.

Transforming growth factor-β in myocardial disease

Transforming growth factor-β (TGFβ) isoforms are upregulated and activated in myocardial diseases and have an important role in cardiac repair and remodelling, regulating the phenotype and function of cardiomyocytes, fibroblasts, immune cells and vascular cells. Cardiac injury triggers the generation of bioactive TGFβ from latent stores, through mechanisms involving proteases, integrins and specialized extracellular matrix (ECM) proteins. Activated TGFβ signals through the SMAD intracellular effectors or through non-SMAD cascades. In the infarcted heart, the anti-inflammatory and fibroblast-activating actions of TGFβ have an important role in repair; however, excessive or prolonged TGFβ signalling accentuates adverse remodelling, contributing to cardiac dysfunction. Cardiac pressure overload also activates TGFβ cascades, which initially can have a protective role, promoting an ECM-preserving phenotype in fibroblasts and preventing the generation of injurious, pro-inflammatory ECM fragments. However, prolonged and overactive TGFβ signalling in pressure-overloaded cardiomyocytes and fibroblasts can promote cardiac fibrosis and dysfunction. In the atria, TGFβ-mediated fibrosis can contribute to the pathogenic substrate for atrial fibrillation. Overactive or dysregulated TGFβ responses have also been implicated in cardiac ageing and in the pathogenesis of diabetic, genetic and inflammatory cardiomyopathies. This Review summarizes the current evidence on the role of TGFβ signalling in myocardial diseases, focusing on cellular targets and molecular mechanisms, and discussing challenges and opportunities for therapeutic translation.

Inhibition of Wnt10b/β-catenin signaling alleviates pulmonary fibrogenesis induced by paraquat in vivo and in vitro

Pulmonary fibrosis (PF) caused by paraquat remains a critical issue, and the molecular mechanisms are still unclear. Epithelial-mesenchymal transition (EMT) is regarded as a hallmark of PF, conferring alveolar epithelial cells partial mesenchymal characteristics, facilitating migration, expressing excessive extracellular matrix components, and participating in lung parenchyma remodeling and stiffening. Aberration of Wnt signaling has been identified in EMT and PF, and Wnt protein family consists of 19 ligands. The relationship of the specific Wnt ligands and fibrogenesis induced by PQ was not well defined. In current study, PQ-induced lung fibrosis rat model and EMT cell model were utilized to investigate the underlying molecular mechanisms both in vivo and in vitro. The results demonstrated that canonical Wnt/β-catenin signaling was highly activated and Wnt10b was the most affected. Additionally, suppression of Wnt10b by RNA interference could reverse EMT in vitro and detain the process of PF in vivo. These data establish Wnt10b as the key regulator of EMT and lung fibrogenesis, and suggest the potential of targeted interference against Wnt10b as a promising therapeutic strategy for lung fibrosis.

A phycocyanin derived eicosapeptide attenuates lung fibrosis development

Pulmonary fibrosis (PF) is a progressive respiratory disease. Phycocyanin derived eicosapeptide (PP20) is a novel peptide derived from active protein C-phycocyanin in Cyanobacteria. The aim of our study was to explore the anti-fibrotic activity of the PP20 and its underlying mechanism. Characteristic features of pulmonary fibrosis in oleic acid (OA)-induced mice and epithelial-mesenchymal transition (EMT) in TGF-β1-exposed A549 and HFL-1 cells with or without PP20 and the change of TGF-β/Smad and MAPK signaling pathways were examined. Smad and MAPK agonists were used to explore the role of TGF-β/Smad and MAPK signaling in TGF-β1- induced collagen I expression in A549 cells and α-SMA expression in HFL-1 cells when treated with PP20. Our results showed that PP20 significantly alleviated the inflammatory response and tissue destruction, inhibited EMT, restored the imbalance of TIMP-1/MMP-9 and reduced collagen fiber deposition. Moreover, PP20 inhibited TGF-β1-induced EMT and collagen I expression in A549 cells. PP20 could also inhibit the proliferation, and decrease TGF-β1-induced the expression of collagen I and transformation of fibroblasts into myofibroblasts in HFL-1 cells. Additionally, animal experiments and cell experiments combined with pathway agonists have shown that PP20 can negatively regulate TGF-β/Smad and MAPK pathways and show anti-fibrotic properties. PP20 may be a promising drug candidate for protection against pulmonary fibrosis.

Macrophage exosomes transfer angiotensin II type 1 receptor to lung fibroblasts mediating bleomycin-induced pulmonary fibrosis

BACKGROUND

Macrophages are involved in the pathogenesis of idiopathic pulmonary fibrosis, partially by activating lung fibroblasts. However, how macrophages communicate with lung fibroblasts is largely unexplored. Exosomes can mediate intercellular communication, whereas its role in lung fibrogenesis is unclear. Here we aim to investigate whether exosomes can mediate the crosstalk between macrophages and lung fibroblasts and subsequently induce fibrosis.

METHODS

In vivo, bleomycin (BLM)-induced lung fibrosis model was established and macrophages infiltration was examined. The effects of GW4869, an exosomes inhibitor, on lung fibrosis were assessed. Moreover, macrophage exosomes were injected into mice to observe its pro-fibrotic effects. In vitro, exosomes derived from angiotensin II (Ang II)-stimulated macrophages were collected. Then, lung fibroblasts were treated with the exosomes. Twenty-four hours later, protein levels of α-collagen I, angiotensin II type 1 receptor (AT1R), transforming growth factor-β (TGF-β), and phospho-Smad2/3 (p-Smad2/3) in lung fibroblasts were examined. The Student's t test or analysis of variance were used for statistical analysis.

RESULTS

In vivo, BLM-treated mice showed enhanced infiltration of macrophages, increased fibrotic alterations, and higher levels of Ang II and AT1R. GW4869 attenuated BLM-induced pulmonary fibrosis. Mice with exosomes injection showed fibrotic features with higher levels of Ang II and AT1R, which was reversed by irbesartan. In vitro, we found that macrophages secreted a great number of exosomes. The exosomes were taken by fibroblasts and resulted in higher levels of AT1R (0.22 ± 0.02 vs. 0.07 ± 0.02, t = 8.66, P = 0.001), TGF-β (0.54 ± 0.05 vs. 0.09 ± 0.06, t = 10.00, P < 0.001), p-Smad2/3 (0.58 ± 0.06 vs. 0.07 ± 0.03, t = 12.86, P < 0.001) and α-collagen I (0.27 ± 0.02 vs. 0.16 ± 0.01, t = 7.01, P = 0.002), and increased Ang II secretion (62.27 ± 7.32 vs. 9.56 ± 1.68, t = 12.16, P < 0.001). Interestingly, Ang II increased the number of macrophage exosomes, and the protein levels of Alix (1.45 ± 0.15 vs. 1.00 ± 0.10, t = 4.32, P = 0.012), AT1R (4.05 ± 0.64 vs. 1.00 ± 0.09, t = 8.17, P = 0.001), and glyceraldehyde-3-phosphate dehydrogenase (2.13 ± 0.36 vs. 1.00 ± 0.10, t = 5.28, P = 0.006) were increased in exosomes secreted by the same number of macrophages, indicating a positive loop between Ang II and exosomes production.

CONCLUSIONS

Exosomes mediate intercellular communication between macrophages and fibroblasts plays an important role in BLM-induced pulmonary fibrosis.

Circulating microRNA-15b-5p as a biomarker for asthma-COPD overlap

BACKGROUND

It remains unclear how to characterize different subtypes of asthma and chronic obstructive pulmonary disease (COPD). We previously described serum periostin and chitinase-3-like protein 1 (YKL-40) as useful markers for asthma-COPD overlap (ACO). MicroRNAs (miRNAs) are now recognized as markers for identifying the pathophysiological features in several diseases. This study aimed to identify circulating miRNAs that could discriminate patients with ACO from patients with asthma or COPD.

METHODS

This study included two independent cohorts. First, we screened 84 miRNAs for expression levels in patients with ACO (n = 6) or asthma (n = 6) using a quantitative real-time PCR array. The miRNAs showing at least a 2-fold difference in the discovery phase were analyzed in 30 patients each with asthma, COPD, or ACO in the replication phase. The diagnostic accuracy was evaluated using the area under the receiver operating characteristic curve (AUROC).

RESULTS

Nine miRNAs were identified in the discovery phase. Five of these miRNAs (miR-148a-3p, miR-15b-5p, miR-223-3p, miR-23a-3p, and miR-26b-5p) had lower levels in ACO patients and could discriminate between ACO patients and patients with either asthma or COPD. miR-15b-5p was the most accurate miRNA for the discrimination of patients with ACO (AUROC, 0.71). Moreover, the combined assessment of miR-15b-5p, serum periostin, and YKL-40 (AUROC, 0.80) improved diagnostic accuracy for ACO compared with the combined model of periostin and YKL-40 (AUROC, 0.69).

CONCLUSIONS

Circulating miR-15b-5p is a potential marker for identifying patients with ACO. By elucidating the molecular pathways controlled by miRNAs, we may better understand the pathophysiology of ACO.

Antisense Oligonucleotides Targeting Jagged 1 Reduce House Dust Mite-induced Goblet Cell Metaplasia in the Adult Murine Lung

Goblet cell metaplasia, excessive mucus production, and inadequate mucus clearance accompany and exacerbate multiple chronic respiratory disorders, such as asthma and chronic obstructive pulmonary disease. Notch signaling plays a central role in controlling the fate of multiple cell types in the lung, including goblet cells. In the present study, we explored the therapeutic potential of modulating the Notch pathway in the adult murine lung using chemically modified antisense oligonucleotides (ASOs). To this end, we designed and characterized ASOs targeting the Notch receptors Notch1, Notch2, and Notch3 and the Notch ligands Jag1 (Jagged 1) and Jag2 (Jagged 2). Pulmonary delivery of ASOs in healthy mice or mice exposed to house dust mite, a commonly used mouse model of asthma, resulted in a significant reduction of the respective mRNAs in the lung. Furthermore, ASO-mediated knockdown of Jag1 or Notch2 in the lungs of healthy adult mice led to the downregulation of the club cell marker Scgb1a1 and the concomitant upregulation of the ciliated cell marker FoxJ1 (forkhead box J1). Similarly, ASO-mediated knockdown of Jag1 or Notch2 in the house dust mite disease model led to reduced goblet cell metaplasia and decreased mucus production. Because goblet cell metaplasia and excessive mucus secretion are a common basis for many lung pathologies, we propose that ASO-mediated inhibition of JAG1 could provide a novel therapeutic path for the treatment of multiple chronic respiratory diseases.

Pharmaceutic application of vitamin D3 on particle-induced fibrotic effects through induction of Nrf2 signals

Fine particulate matter, a major air pollutant across the world, causes a series of pulmonary diseases. Vitamin D is a typical vitamin with emerging roles in inflammation and fibrosis. Different situations and diseases need different doses and modes of vitamin D administration, which challenges the existing vitamin D supplementary rules. Thus, studies of vitamin D applications and their mechanisms in various diseases are important for its future therapeutic applications. In this study, the therapeutic application of vitamin D₃ in chronic particle-exposure-associated lung fibrosis and tissue remodeling was investigated. In vivo studies showed that vitamin D₃ significantly attenuated fibrosis effects by decreasing α-smooth muscle actin-regulated extracellular matrix deposition and restoring expressions of E-cadherin and N-cadherin. With the importance of activated macrophage in the regulation of local epithelium and fibroblast in the process of tissue fibrosis, two separate in vitro systems of co-culture of macrophages with lung epithelium or fibroblast were built. The results confirmed that vitamin D₃ promoted the proliferation of lung epithelium and depressed the fibrosis effects of fibroblasts as well. In addition, our results indicated that the therapeutic effects of vitamin D₃ were through Nrf2 signals. Our work provides convincing experimental evidence for vitamin D therapeutic application to promote tissue repair and improve particle-associated lung fibrosis.

Impact of the Local Inflammatory Environment on Mucosal Vitamin D Metabolism and Signaling in Chronic Inflammatory Lung Diseases

Vitamin D plays an active role in the modulation of innate and adaptive immune responses as well as in the protection against respiratory pathogens. Evidence for this immunomodulatory and protective role is derived from observational studies showing an association between vitamin D deficiency, chronic airway diseases and respiratory infections, and is supported by a range of experimental studies using cell culture and animal models. Furthermore, recent intervention studies have now shown that vitamin D supplementation reduces exacerbation rates in vitamin D-deficient patients with chronic obstructive pulmonary disease (COPD) or asthma and decreases the incidence of acute respiratory tract infections. The active vitamin D metabolite, 1,25-dihydroxy-vitamin D (1,25(OH)₂D), is known to contribute to the integrity of the mucosal barrier, promote killing of pathogens (via the induction of antimicrobial peptides), and to modulate inflammation and immune responses. These mechanisms may partly explain its protective role against infections and exacerbations in COPD and asthma patients. The respiratory mucosa is an important site of local 1,25(OH)₂D synthesis, degradation and signaling, a process that can be affected by exposure to inflammatory mediators. As a consequence, mucosal inflammation and other disease-associated factors, as observed in e.g., COPD and asthma, may modulate the protective actions of 1,25(OH)₂D. Here, we discuss the potential consequences of various disease-associated processes such as inflammation and exposure to pathogens and inhaled toxicants on vitamin D metabolism and local responses to 1,25(OH)₂D in both immune- and epithelial cells. We furthermore discuss potential consequences of disturbed local levels of 25(OH)D and 1,25(OH)₂D for chronic lung diseases. Additional insight into the relationship between disease-associated mechanisms and local effects of 1,25(OH)₂D is expected to contribute to the design of future strategies aimed at improving local levels of 1,25(OH)₂D and signaling in chronic inflammatory lung diseases.

Structural Characterization and Pro-inflammatory Activity of a Thaumatin-Like Protein from Pulp Tissues of Litchi chinensis

The objective of this study was to extract and purify proteins from the pulp tissues of litchi and evaluate their structure and pro-inflammatory activity. The results showed that a highly pure litchi protein was identified as the litchi thaumatin-like protein (LcTLP) by nano LC-MS/MS and verified by sequencing of the LcTLP gene. The molecular weight was 24 kDa, and the main secondary structure was a β sheet (33.00 ± 2.86%). Small-angle X-ray scattering results showed that LcTLP was a spherical particle (diameter of approximately 140 to 165 nm) with a close internal and rough surface in solution. The assay of pro-inflammatory activity in vitro revealed that the expression of inducible nitric oxide synthase and cyclooxygenase-2 genes reached 9.71 ± 0.64 and 7.05 ± 1.00 after 200 μg/mL LcTLP stimulation, which were 7.05-fold and 9.61-fold that of the blank control, respectively. LcTLP promoted the gene expression and production of pro-inflammatory cytokines, including tumor necrosis factor-α and interleukin-1β, and it also enhanced the expression of p65, which is a key component of nuclear factor-κ B signaling pathways. Additionally, the levels of anti-inflammatory cytokines interleukin-10 and transforming growth factor-β1 increased after LcTLP stimulation.

Overexpression of TIM-3 in Macrophages Aggravates Pathogenesis of Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive lung disorder and lacks effective treatments because of unclear mechanisms. Aberrant function of alveolar macrophages is directly linked to pulmonary fibrosis. Here, we show TIM-3 (T-cell immunoglobulin domain and mucin domain-3), a key regulator of macrophage function, aggravates pulmonary fibrosis. TIM-3 mRNA of patients with IPF was analyzed based on the Gene Expression Omnibus and Array Express databases. Lung pathology and profibrotic molecules were assessed in a bleomycin (BLM)-induced pulmonary fibrosis model using wild-type (WT) and TIM-3 transgenic (TIM-3-TG) mice. Macrophage cells, RAW264.7, were then applied to investigate the effect of macrophage TIM-3 under BLM exposure in vitro. Macrophage depletion and adoptive-transfer experiments were finally performed to examine lung morphology and profibrotic molecules. TIM-3 expression was increased both in patients with IPF and in our BLM-induced mouse model. TIM-3-TG mice developed more serious pathological changes in lung tissue and higher expressions of TGF-β1 (transforming growth factor-β1) and IL-10 than WT mice. After BLM treatment, TGF-β1 and IL-10 expression was significantly decreased in RAW264.7 cells after TIM-3 knock-out, whereas it was increased in TIM-3-TG peritoneal macrophages. The scores of pulmonary fibrosis in WT and TIM-3-TG mice were significantly reduced, and there was no difference between them after macrophage depletion. Furthermore, WT mice receiving adoptive macrophages from TIM-3-TG mice also had more serious lung fibrosis and increased expression of TGF-β1 and IL-10 than those receiving macrophages from WT mice. Our findings revealed that overexpressed TIM-3 in alveolar macrophages aggravated pulmonary fibrosis.

Alternatively activated macrophages; a double-edged sword in allergic asthma

BACKGROUND

Macrophages are heterogenous phagocytic cells with an important role in the innate immunity. They are, also, significant contributors in the adaptive immune system. Macrophages are the most abundant immune cells in the lung during allergic asthma, which is the most common chronic respiratory disease of both adults and children. Macrophages activated by Th1 cells are known as M1 macrophages while those activated by IL-4 and IL-13 are called alternatively activated macrophages (AAM) or M2 cells. AAM are subdivided into four distinct subtypes (M2a, M2b, M2c and M2d), depending on the nature of inducing agent and the expressed markers. BODY: IL-4 is the major effector cytokine in both alternative activation of macrophages and pathogenesis of asthma. Thus, the role of M2a macrophages in asthma is a major concern. However, this is controversial. Therefore, further studies are required to improve our knowledge about the role of IL-4-induced macrophages in allergic asthma, through precisive elucidation of the roles of specific M2a proteins in the pathogenesis of asthma. In the current review, we try to illustrate the different functions of M2a macrophages (protective and pathogenic roles) in the pathogenesis of asthma, including explanation of how different M2a proteins and markers act during the pathogenesis of allergic asthma. These include surface markers, enzymes, secreted proteins, chemokines, cytokines, signal transduction proteins and transcription factors.

CONCLUSIONS

AAM is considered a double-edged sword in allergic asthma. Finally, we recommend further studies that focus on increased selective expression or suppression of protective and pathogenic M2a markers.

TGF-β1 - A truly transforming growth factor in fibrosis and immunity

'Jack of all trades, master of everything' is a fair label for transforming growth factor β1 (TGF-β) - a cytokine that controls our life at many levels. In the adult organism, TGF-β1 is critical for the development and maturation of immune cells, maintains immune tolerance and homeostasis, and regulates various aspects of immune responses. Following acute tissue damages, TGF-β1 becomes a master regulator of the healing process with impacts on about every cell type involved. Divergence from the tight control of TGF-β1 actions, for instance caused by chronic injury, severe trauma, or infection can tip the balance from regulated physiological to excessive pathological repair. This condition of fibrosis is characterized by accumulation and stiffening of collagenous scar tissue which impairs organ functions to the point of failure. Fibrosis and dysregulated immune responses are also a feature of cancer, in which tumor cells escape immune control partly by manipulating TGF-β1 regulation and where immune cells are excluded from the tumor by fibrotic matrix created during the stroma 'healing' response. Despite the obvious potential of TGF-β-signalling therapies, globally targeting TGF-β1 receptor, downstream pathways, or the active growth factor have proven to be extremely difficult if not impossible in systemic treatment regimes. However, TGF-β1 binding to cell receptors requires prior activation from latent complexes that are extracellularly presented on the surface of immune cells or within the extracellular matrix. These different locations have led to some divergence in the field which is often either seen from the perspective of an immunologists or a fibrosis/matrix researcher. Despite these human boundaries, there is considerable overlap between immune and tissue repair cells with respect to latent TGF-β1 presentation and activation. Moreover, the mechanisms and proteins employed by different cells and spatiotemporal control of latent TGF-β1 activation provide specificity that is amenable to drug development. This review aims at synthesizing the knowledge on TGF-β1 extracellular activation in the immune system and in fibrosis to further stimulate cross talk between the two research communities in solving the TGF-β conundrum.

Targeting cell signaling in allergic asthma

Asthma is chronic inflammation of the airways characterized by airway hyper-responsiveness, wheezing, cough, and dyspnea. Asthma affects >350 million people worldwide. The Th2 immune response is a major contributor to the pathophysiology of asthma. Targeted therapy modulating cell signaling pathways can be a powerful strategy to design new drugs to treat asthma. The potential molecular pathways that can be targeted include IL-4-IL-13-JAK-STAT-MAP kinases, adiponectin-iNOS-NF-κB, PGD2-CRTH2, IFNs-RIG, Wnt/β-catenin-FAM13A, FOXC1-miR-PI3K/AKT, JNK-Gal-7, Nrf2-ROS, Foxp3-RORγt, CysLTR, AMP, Fas-FasL, PTHrP/PPARγ, PAI-1, FcɛRI-LAT-SLP-76, Tim-3-Gal-9, TLRs-MyD88, PAR2, and Keap1/Nrf2/ARE. Therapeutic drugs can be designed to target one or more of these pathways to treat asthma.

Thrombospondin 1 and Its Diverse Roles as a Regulator of Extracellular Matrix in Fibrotic Disease

Thrombospondin 1 (TSP1) is a matricellular extracellular matrix protein that has diverse roles in regulating cellular processes important for the pathogenesis of fibrotic diseases. We will present evidence for the importance of TSP1 control of latent transforming growth factor beta activation in renal fibrosis with an emphasis on diabetic nephropathy. Other functions of TSP1 that affect renal fibrosis, including regulation of inflammation and capillary density, will be addressed. Emerging roles for TSP1 N-terminal domain regulation of collagen matrix assembly, direct effects of TSP1-collagen binding, and intracellular functions of TSP1 in mediating endoplasmic reticulum stress responses in extracellular matrix remodeling and fibrosis, which could potentially affect renal fibrogenesis, will also be discussed. Finally, we will address possible strategies for targeting TSP1 functions to treat fibrotic renal disease.

Controlling the Multiscale Network Structure of Fibers To Stimulate Wound Matrix Rebuilding by Fibroblast Differentiation

The extracellular matrix (ECM) plays the role of a double-edged sword for controlling the differentiation of fibroblasts toward contractile myofibroblasts in the wound healing process. However, the exact structure-function relationship between ECM morphology and fibroblast behaviors still remains unclear. To better understand this relationship, herein, we designed and prepared a series of biocompatible polycaprolactone (PCL)-based fibers with different fiber diameters (nano vs micro) and different alignments (random vs aligned) using a simple electrospinning process, with a particular attention to the morphological effect of PCL fiber scaffolds on guiding fibroblast behaviors. Microfibers with the larger fiber diameters induce less cell spreading, adhesion, differentiation, and migration because of their lower surface tension. In contrast, nanofibers will retain fibroblast cells with typical spindle shapes and promote the expression of focal adhesion proteins through the integrin pathway. Furthermore, nanofibers upregulate the expression of α-smooth muscle actin (α-SMA), transforming growth factor, and vimentin filaments, indicating that the size change of the PCL fiber matrix from micrometers to nanometers indeed alters fibroblast differentiation to activate more α-SMA-expressed contractile myofibroblasts. Such a fiber size-dependent fibroblast behavior is largely attributed to the enhanced surface tension from the dressing matrix, which helps to promote the conversion of fibroblasts to myofibroblasts via either tissue regeneration or fibrosis. Therefore, this work further indicated that the rearrangement of collagen from nano-tropocollagen to micro-collagen bundles during the wound healing process can reverse fibroblasts to myofibroblasts from motivated to demise. This finding allows us to achieve the structural-based design of a new fibrous matrix for promoting wound healing and tissue regeneration.

Vitamin D protects against particles-caused lung injury through induction of autophagy in an Nrf2-dependent manner

Fine particulate matter is a well-known air pollutant threatening public health. Studies have confirmed long-term exposure to the particles could decrease the pulmonary function, induce asthma exacerbation, and chronic obstructive pulmonary disease, as well as increase the incidence and mortality of lung cancer. A clinical study has explored that the prevalence and risks of vitamin D (VD) deficiency in various chronic disease and toxins induced tissue damage. Our current study aimed to explore the mechanism and further therapeutic potential of VD administration to ameliorate fine particles exposure induced pulmonary damage in vivo and in vitro. To elucidate the effects and mechanisms of VD in particles-induced pulmonary damage, a murine model was established with fine particles intratracheal instillation along with VD intramuscular injection. Our study demonstrated that treatment with VD attenuated particles-induced pulmonary damage and promoted tissue repair by repressing of TGFβ1 signaling pathway and upregulation of MMP9 expression. VD treatment could also regulate the autophagy-related signals along with activation of Nrf2 transcription factor. Furthermore, the results from the in vitro study demonstrated that VD protected against particles-induced cells' damage through the induction of autophagy in an Nrf2-dependent manner. VD treatment caused the degradation of P62 and its bound Keap1, which decreased the Nrf2 ubiquitination and increasing its protein stability. Our work explored a novel potential mechanism in the protection of VD in particles-induced pulmonary injury and tissue repair, and could further bring insights into exploring antifine particles exposure caused inflammation among other natural products and contributes to inflammation disease medical therapies.

TGF-β1 Impairs Vitamin D-Induced and Constitutive Airway Epithelial Host Defense Mechanisms

Airway epithelium is an important site for local vitamin D (VD) metabolism; this can be negatively affected by inflammatory mediators. VD is an important regulator of respiratory host defense, for example, by increasing the expression of hCAP18/LL-37. TGF-β1 is increased in chronic obstructive pulmonary disease (COPD), and known to decrease the expression of constitutive host defense mediators such as secretory leukocyte protease inhibitor (SLPI) and polymeric immunoglobulin receptor (pIgR). VD has been shown to affect TGF-β1-signaling by inhibiting TGF-β1-induced epithelial-to-mesenchymal transition. However, interactions between VD and TGF-β1, relevant for the understanding host defense in COPD, are incompletely understood. Therefore, the aim of the present study was to investigate the combined effects of VD and TGF-β1 on airway epithelial cell host defense mechanisms. Exposure to TGF-β1 reduced both baseline and VD-induced expression of hCAP18/LL-37, partly by increasing the expression of the VD-degrading enzyme CYP24A1. TGF-β1 alone decreased the number of secretory club and goblet cells and reduced the expression of constitutive host defense mediators SLPI, s/lPLUNC and pIgR, effects that were not modulated by VD. These results suggest that TGF-β1 may decrease the respiratory host defense both directly by reducing the expression of host defense mediators, and indirectly by affecting VD-mediated effects such as expression of hCAP18/LL-37.

Association of anti-inflammatory and antiangiogenic therapies negatively influences prostate cancer progression in TRAMP mice

BACKGROUND

Chronic inflammation has been implicated in cancer etiology and angiogenesis is stimulated in this disease. In prostate, the crosstalk between malignant epithelial cells and their microenvironment is an essential step of tumorigenesis during which glandular stroma undergo changes designated as reactive stroma. Thus, the aim herewith was to evaluate the effects of associating anti-inflammatory and antiangiogenic therapies on cancer progression, correlating them with steroid hormone receptor (AR and ERα), reactive stroma (vimentin, αSMA, and TGF-β), and cell proliferation (PCNA) markers expression in the Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) model.

METHODS

TRAMP mice (12-week old) were divided into the groups: Control (TRCON): received the vehicles used for drug dilution; Celecoxib (TRCEL): received oral doses of the anti-inflammatory drug celecoxib (15 mg/kg) twice daily; Nintedanib (TRNTB): received oral doses of the antiangiogenic drug nintedanib (10 mg/kg) daily; Nintedanib+Celecoxib (TRNTCEL): received the combination of drugs. After 6 weeks, mice were euthanized and ventral prostate samples were harvested for morphological, immunohistochemical, and Western blotting analyses.

RESULTS

While celecoxib led to fibromuscular hypertrophy attenuation, nintedanib significantly reduced the incidence of well-differentiated adenocarcinoma (WDAC) foci in relation to controls, both when administered per se or in association to celecoxib. Furthermore, drug combination was associated with unique effects, including lower incidence of HGPIN lesions; lower AR stromal distribution; changes in ERα localization from epithelial nuclei to stroma as well as significant decrease of TGF-β levels and associated angiogenesis. In parallel, all treatments applied resulted in reduced inflammatory marker and vimentin (VIM) expression.

CONCLUSIONS

Celecoxib plus nintedanib is an effective antitumor combination against prostate cancer progression in TRAMP mice, showing remarkable efficacy in relation to isolated therapies. Importantly, this efficacy might be due to drug association effect on driving AR and mainly ERα distribution in the prostatic tissue towards benign patterns. In addition, celecoxib and nintedanib impaired the development of a stromal reaction by reducing the recruitment of reactive stroma cells and maintaining a normal smooth muscle cell-rich prostate stroma in TRAMP mice. Collectively, these findings pointed to the beneficial effects of combining anti-inflammatory and antiangiogenic strategies to prevent or delay prostatic tumorigenesis.

A Non-canonical Pathway with Potential for Safer Modulation of Transforming Growth Factor-β1 in Steroid-Resistant Airway Diseases

Impaired therapeutic responses to anti-inflammatory glucocorticoids (GC) in chronic respiratory diseases are partly attributable to interleukins and transforming growth factor β1 (TGF-β1). However, previous efforts to prevent induction of GC insensitivity by targeting established canonical and non-canonical TGF-β1 pathways have been unsuccessful. Here we elucidate a TGF-β1 signaling pathway modulating GC activity that involves LIM domain kinase 2-mediated phosphorylation of cofilin1. Severe, steroid-resistant asthmatic airway epithelium showed increased levels of immunoreactive phospho-cofilin1. Phospho-cofilin1 was implicated in the activation of phospholipase D (PLD) to generate the effector(s) (lyso)phosphatidic acid, which mimics the TGF-β1-induced GC insensitivity. TGF-β1 induction of the nuclear hormone receptor corepressor, SMRT (NCOR2), was dependent on cofilin1 and PLD activities. Depletion of SMRT prevented GC insensitivity. This pathway for GC insensitivity offers several promising drug targets that potentially enable a safer approach to the modulation of TGF-β1 in chronic inflammatory diseases than is afforded by global TGF-β1 inhibition.

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TGF-β1 extensively impairs GC activity

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Phospho-cofilin1 is a key link in TGF-β1 signaling cascade subserving GC insensitivity

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Phospho-cofilin1-activated phospholipase D (PLD) reduces GC activity

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SMRT induction downstream of PLD mediates TGF-β1 impairment of GC activity

The roles of microRNAs in the pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive and irreversible airflow obstruction, with an abnormal lung function. The etiology of COPD correlates with complex interactions between environmental and genetic determinants. However, the exact pathogenesis of COPD is obscure although it involves multiple aspects including oxidative stress, imbalance between proteolytic and anti-proteolytic activity, immunity and inflammation, apoptosis, and repair and destruction in both airways and lungs. Many genes have been demonstrated to be involved in those pathogenic processes of this disease in patients exposed to harmful environmental factors. Previous reports have investigated promising microRNAs (miRNAs) to disclose the molecular mechanisms for COPD development induced by different environmental exposure and genetic predisposition encounter, and find some potential miRNA biomarkers for early diagnosis and treatment targets of COPD. In this review, we summarized the expression profiles of the reported miRNAs from studies of COPD associated with environmental risk factors including cigarette smoking and air pollution exposures, and provided an overview of roles of those miRNAs in the pathogenesis of the disease. We also highlighted the potential utility and limitations of miRNAs serving as diagnostic biomarkers and therapeutic targets for COPD.

Therapeutic potential of bixin in PM2.5 particles-induced lung injury in an Nrf2-dependent manner

Fine particulate matter (PM 2.5) is a well-known air pollutant threatening public health. Studies has confirmed that long-term exposure to the particles could reduce the pulmonary function, cause exacerbation of asthma and chronic obstructive pulmonary disease, and increase incidence and mortality of lung cancer. Bixin is a natural compound that is widely used as a food additive. Our previous studies demonstrated that bixin i.p. administration could protect against particles intratracheal exposure (56 days)-induced lung injury in an Nrf2-dependent manner. But the detail mechanisms are still unclarified. Our current study aimed to explore the further therapeutic potential and mechanism of bixin to slow the progression of lung injury and inflammation in vivo and in vitro. The results from the in vivo study showed that bixin treatment attenuated the accumulation of inflammatory cells, decreased the levels of tissue apoptosis, and increase the ability of cell proliferation. Besides that, bixin also could regulate the expression of MMP9, TGFβ1, and its downstream Fibronectin (FN), along with activation of Nrf2 signals. In vitro experiments in human bronchial epithelial cells demonstrated that Nrf2 activated by bixin contributes to tissue repair by alleviating oxidative stress, increasing proliferation and migration, decreasing apoptosis, which may be partially through modulating the expression of MMP9, TGFβ1, and FN. This study provides convincing experimental evidences that bixin could be used therapeutically to promote tissue repair and improve pulmonary injury induced by particles exposure.

Polydatin attenuates reactive oxygen species-induced airway remodeling by promoting Nrf2-mediated antioxidant signaling in asthma mouse model

Reactive oxygen species (ROS) and epithelial-mesenchymal transition (EMT) play a critical role in transforming growth factor (TGF)-β1-mediated fibrotic airway remodeling in asthma. Polydatin (PD) is a small natural molecule in Chinese medicine; it is isolated from Polygonum cuspidatum and has antioxidative properties. In this study, we aimed to determine whether PD was protective against ROS-induced pulmonary fibrosis in asthma. Ovalbumin (OVA) was used to induce asthma in a mouse model that was treated with or without PD. We also created nuclear factor erythroid 2-related factor 2 (Nrf2) knockdown BEAS-2B cells and investigated whether PD reversed TGF-β1-induced pulmonary epithelial cell EMT by promotion of Nrf2-mediated antioxidation. Immunofluorescence showed that ROS and TGF-β1 expression was significantly increased in lung tissue from the OVA-induced asthma model. PD treatment inhibited activity of ROS and TGF-β1. Immunohistochemistry showed that PD treatment decreased OVA-induced lung ROS, TGF-β1 expression and fibroblasts. Western blotting showed that PD treatment reversed OVA-induced NADPH oxidase (NOX)1/4 expression by promoting Nrf2-mediated heme oxygenase-1 and NADPH dehydrogenase (quinone)-1 expression. PD treatment suppressed OVA-induced EMT and lung fibroblast protein expression in lung tissue. Nrf2 downregulation suppressed the protective effect of PD by promoting TGF-β1-induced ROS and EMT and accumulation of extracellular-matrix-related protein. All these data indicate that PD has potential therapeutic effects in asthma by promoting Nrf2-mediated antioxidation.

Casein Kinase 1δ/ε Inhibitor, PF670462 Attenuates the Fibrogenic Effects of Transforming Growth Factor-β in Pulmonary Fibrosis

Transforming growth factor-beta (TGF-β) is a major mediator of fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). However, therapeutic global inhibition of TGF-β is limited by unwanted immunosuppression and mitral valve defects. We performed an extensive literature search to uncover a little-known connection between TGF-β signaling and casein kinase (CK) activity. We have examined the abundance of CK1 delta and epsilon (CK1δ/ε) in lung tissue from IPF patients and non-diseased controls, and investigated whether inhibition of CK1δ/ε with PF670462 inhibits pulmonary fibrosis. CK1δ/ε levels in lung tissue from IPF patients and non-diseased controls were assessed by immunohistochemistry. Anti-fibrotic effects of the CK1δ/ε inhibitor PF670462 were assessed in pre-clinical models, including acute and chronic bleomycin mouse models and in vitro experiments on spheroids made from primary human lung fibroblast cells from IPF and control donors, and human A549 alveolar-like adenocarcinoma-derived epithelial cells. Increased expression of CK1δ and ε in IPF lungs compared to non-diseased controls was accompanied by increased levels of the product, phospho-period 2. In vitro, PF670462 prevented TGF-β-induced epithelial-mesenchymal transition. The stiffness of IPF-derived spheroids was reduced by PF670462 and TGF-β-induced fibrogenic gene expression was inhibited. The CK1δ/ε inhibitor PF670462 administered systemically or locally by inhalation prevented both acute and chronic bleomycin-induced pulmonary fibrosis in mice. PF670462 administered in a 'therapeutic' regimen (day 7 onward) prevented bleomycin-induced lung collagen accumulation. Elevated expression and activity of CK1 δ and ε in IPF and anti-fibrogenic effects of the dual CK1δ/ε inhibitor, PF670462, support CK1δ/ε as novel therapeutic targets for IPF.