Epithelial-Mesenchymal Transition in Asthma Airway Remodeling Is Regulated by the IL-33/CD146 Axis

Untargeted serum metabonomic reveals alleviated ovalbumin-induced asthma by Baijin Pingchuan through primary bile acid biosynthesis

OBJECTIVE

To investigate the effect of baijinpingchuan (, BJPC) on the asthma rat model and identify differential metabolites and disturbed metabolic pathways.

METHODS

The rats were categorized into six groups: control, dexamethasone (DEX), ovalbumin (OVA), and low-, median-, and high-dose BJPC. The rats, except for the control group, were initially treated with OVA to develop the asthma model, which was then activated using DEX, OVA, and low-, median-, and high-dose BJPC. Enzyme-linked immunosorbent assay kit was used to detect the expression of interleukin (IL)-33, IL-25, thymic stromal lymphopoietin (TSLP), and transforming growth factor-beta 1 (TGF-β1). Hematoxylin and eosin staining were performed to observe the pathological condition of the lung. Untargeted serum metabonomic analysis was conducted to identify differential metabolites and disturbed metabolic pathways.

RESULTS

High-dose BJPC significantly inhibited the expression of IL-33, IL-25, TSLP, and TGF-β1 (P < 0.0001). Further, high-dose BJPC improved inflammatory cell infiltration, which plays a similar role in asthma as DEX. OVA-induced and BJPC-treated rats were identified through 17 differential metabolites, especially cholic acid. Furthermore, primary bile acid biosynthesis was a significantly differential pathway in the mechanism of BJPC for treating asthma.

CONCLUSIONS

BJPC plays an anti-inflammation role in asthma, which might be a promising therapy through mediating primary bile acid biosynthesis.

Effects of MAL gene knockout on lung tissue morphology and on E-cad and α-SMA expression in asthma mouse models

OBJECTIVES

To investigate the effects of myelin- and lymphocyte-associated protein (MAL) gene knockout on the morphological structure of lung tissue and the expression of E-cadherin (E-cad) and alpha-smooth muscle actin (α-SMA) in an asthmatic mouse model.

METHODS

Twenty-four specific pathogen-free (SPF) C57BL/6J mice were divided into four groups: the wild-type normal (WT/SAL), wild-type asthmatic (WT/OVA), gene knockout normal (MAL-/-/SAL), and gene knockout asthmatic (MAL-/-/OVA) groups. The establishment of the asthma mouse models was confirmed by evaluating behavioral symptoms and histopathological H&E and Masson staining. Western blotting and RT-qPCR were used to measure E-cad and α-SMA expression levels in lung tissues.

RESULTS

H&E staining of mouse lung tissues from WT/OVA, MAL-/-/SAL, and MAL-/-/OVA groups revealed a thickened bronchial wall, irregular lumen edge, locally fallen mucosal epithelium, and inflammatory cell infiltration compared with those of the WT/SAL group. In the WT and MAL-/- groups, the proportion of Masson-stained tissues in the OVA group was greater than that in the SAL group (p < 0.05). Compared with those in the WT/SAL group, the expression levels of α-SMA mRNA and protein were increased, while those of E-cad were decreased in the WT/OVA group (p < 0.01). Similarly, compared with those in the MAL-/-/SAL group, the expression levels of E-cad mRNA and protein were increased, while those of α-SMA were decreased in the MAL-/-/OVA group (p < 0.01). All these differences were statistically significant (p < 0.01).

CONCLUSIONS

The MAL gene contributes to EMT inhibition and the stability of the airway barrier under normal physiological conditions by regulating E-cad and α-SMA expression.

Inhibition of long non-coding RNA NEAT1 suppressed the epithelial mesenchymal transition through the miR-204-5p/Six1 axis in asthma

BACKGROUND

Asthma, a prevalent chronic respiratory condition, is characterized by airway remodeling. Long non-coding RNA (lncRNA) NEAT1 has been demonstrated to participate in airway fibrosis. Furthermore, the miR-204-5p/Six1 axis significantly influences epithelial mesenchymal transition (EMT). However, the function of NEAT1/miR-204-5p/Six1 in asthmatic EMT remains unclear.

PURPOSE

This study intends to elucidate the function of NEAT1/miR-204-5p/Six1 axis in asthmatic EMT.

METHODS

TGF-β1 was used to induce the EMT model in BEAS-2B cells. Immunofluorescence and western blot were executed to verify the establishment of the EMT model. NEAT1, miR-204-5p, and Six1 expression levels were evaluated using RT-qPCR. The role of NEAT1 in EMT in vitro was explored by CCK8 assays and flow cytometry. The luciferase reporter assay was performed to validate the interaction between NEAT1 and miR-204-5p/Six1.

RESULTS

NEAT1 expression was increased during EMT. Functional experiments showed that the knockdown of NEAT1 suppressed cell proliferation and promoted cell apoptosis in vitro. Furthermore, inhibition of NEAT1 decreased the expression of N-cadherin, vimentin, and α-SMA and increased the expression of E-cadherin. Mechanistically, NEAT1 was identified as a sponge for miR-204-5p, and Six1 was found to be a direct target of miR-204-5p.

CONCLUSION

Down-regulation of NEAT1 reduced the Six1 expression via targeting miR-204-5p to inhibit the process of EMT in asthma. This study may provide new insight to reveal the underlying mechanisms of asthma.

Immunologic aspects of asthma: from molecular mechanisms to disease pathophysiology and clinical translation

In the present review, we focused on recent translational and clinical discoveries in asthma immunology, facilitating phenotyping and stratified or personalized interventions for patients with this condition. The immune processes behind chronic inflammation in asthma exhibit marked heterogeneity, with diverse phenotypes defining discernible features and endotypes illuminating the underlying molecular mechanisms. In particular, two primary endotypes of asthma have been identified: "type 2-high," characterized by increased eosinophil levels in the airways and sputum of patients, and "type 2-low," distinguished by increased neutrophils or a pauci-granulocytic profile. Our review encompasses significant advances in both innate and adaptive immunities, with emphasis on the key cellular and molecular mediators, and delves into innovative biological and targeted therapies for all the asthma endotypes. Recognizing that the immunopathology of asthma is dynamic and continuous, exhibiting spatial and temporal variabilities, is the central theme of this review. This complexity is underscored through the innumerable interactions involved, rather than being driven by a single predominant factor. Integrated efforts to improve our understanding of the pathophysiological characteristics of asthma indicate a trend toward an approach based on disease biology, encompassing the combined examination of the clinical, cellular, and molecular dimensions of the disease to more accurately correlate clinical traits with specific disease mechanisms.

ETS1 and RBPJ transcriptionally regulate METTL14 to suppress TGF-β1-induced epithelial-mesenchymal transition in human bronchial epithelial cells

Asthma is a chronic respiratory disease characterized by airway inflammation and remodeling. Epithelial-mesenchymal transition (EMT) of bronchial epithelial cells is considered to be a crucial player in asthma. Methyltransferase-like 14 (METTL14), an RNA methyltransferase, is implicated in multiple pathological processes, including EMT, cell proliferation and migration. However, the role of METTL14 in asthma remains uncertain. This research aimed to explore the biological functions of METTL14 in asthma and its underlying upstream mechanisms. METTL14 expression was down-regulated in asthmatic from three GEO datasets (GSE104468, GSE165934, and GSE74986). Consistent with this trend, METTL14 was decreased in the lung tissues of OVA-induced asthmatic mice and transforming growth factor-β1 (TGF-β1)-stimulated human bronchial epithelial cells (Beas-2B) in this study. Overexpression of METTL14 caused reduction in mesenchymal markers (FN1, N-cad, Col-1 and α-SMA) in TGF-β1-treated cells, but caused increase in epithelial markers (E-cad), thus inhibiting EMT. Also, METTL14 suppressed the proliferation and migration ability of TGF-β1-treated Beas-2B cells. Two transcription factors, ETS1 and RBPJ, could both bind to the promoter region of METTL14 and drive its expression. Elevating METTL14 expression could reversed EMT, cell proliferation and migration promoted by ETS1 or RBPJ deficiency. These results indicate that the ETS1/METTL14 and RBPJ/METTL14 transcription axes exhibit anti-EMT, anti-proliferation and anti-migration functions in TGF-β1-induced bronchial epithelial cells, implying that METTL14 may be considered an alternative candidate target for the treatment of asthma.

The correlation between cancer stem cells and epithelial-mesenchymal transition: molecular mechanisms and significance in cancer theragnosis

The connections between cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) is critical in cancer initiation, progression, metastasis, and therapy resistance, making it a focal point in cancer theragnosis. This review provides a panorama of associations and regulation pathways between CSCs and EMT, highlighting their significance in cancer. The molecular mechanisms underlined EMT are thoroughly explored, including the involvement of key transcription factors and signaling pathways. In addition, the roles of CSCs and EMT in tumor biology and therapy resistance, is further examined in this review. The clinical implications of CSCs-EMT interplay are explored, including identifying mesenchymal-state CSC subpopulations using advanced research methods and developing targeted therapies such as inhibitors and combination treatments. Overall, understanding the reciprocal relationship between EMT and CSCs holds excellent potential for informing the development of personalized therapies and ultimately improving patient outcomes.

A Review on Asthma and Allergy: Current Understanding on Molecular Perspectives

Asthma, a complex disease characterized by persistent airway inflammation, remains an urgent global health concern. We explored the critical role of allergic biomarkers and dysregulated immune system in asthma through an extensive literature review in databases such as Web of Science, PubMed, EMBASE, Scopus, and Google Scholar. This review summarizes the growing data on the pivotal role of allergic biomarkers and dysregulated immune system in the development and evolution of asthma. Recent studies have uncovered several biomarkers that elucidate intrinsic allergic mechanisms in individuals with asthma. This article highlights these biomarkers' potential in predicting asthma onset, assessing its intensity, guiding therapeutic interventions, and tracking disease progression. We also explore the innovative therapeutic prospects arising from the convergence of allergy and dysregulated immune system in asthma and emphasize the potential for precision medicine approaches. Understanding allergic biomarkers intertwined with a dysregulated immune system heralds a new era in asthma treatment and points to improved and individualized treatment modalities.

Atomized inhalation of Icaritin reduces airway inflammation and remodeling in asthmatic mice

BACKGROUND

Asthma is a disease characterized by airway hyperresponsiveness and airway inflammation. Icaritin (ICT) is a plant hormone with various pharmacological activities such as anti-inflammatory, immune regulation, and anti-tumor. This study mainly explored the effects of nebulized inhalation of ICT on airway inflammation and airway remodeling in asthmatic mice.

METHOD

Different groups of ovalbumin (OVA)-induced asthma mice with acute and chronic airway inflammation received ICT. Asthmatic mice received budesonide (BDND) aerosol inhalation as a positive control, while normal control and asthma model mice received the same volume of saline. Following finishing of the study, analyses were conducted on behavioral tests, biochemical indices, and histological structures of lung tissues.

RESULTS

Aerosol inhalation of ICT can notably reduce inflammatory cells infiltration around the airways and pulmonary vessels, and suppressed goblet cell hyperplasia in asthmatic mice. Long-term inhalation of ICT can decrease airway collagen deposition and airway smooth muscle hyperplasia, and alleviate airway hyperresponsiveness, mirroring the effects observed with hormone employed in clinical practice.

CONCLUSION

Nebulized inhalation of ICT can effectively inhibit airway inflammation in asthmatic mice, improve airway remodeling, and reduce airway hyperresponsiveness, with effects similar to those of hormones. It may serve as a potential candidate used as a hormone replacement asthma treatment.

Emerging Roles of Galectin-3 in Pulmonary Diseases

Galectin-3 is a multifunctional protein that is involved in various physiological and pathological events. Emerging evidence suggests that galectin-3 also plays a critical role in the pathogenesis of pulmonary diseases. Galectin-3 can be produced and secreted by various cell types in the lungs, and the overexpression of galectin-3 has been found in acute lung injury/acute respiratory distress syndrome (ALI/ARDS), pulmonary hypertension (PH), pulmonary fibrosis diseases, lung cancer, lung infection, chronic obstructive pulmonary disease (COPD), and asthma. Galectin-3 exerts diverse effects on the inflammatory response, immune cell activation, fibrosis and tissue remodeling, and tumorigenesis in these pulmonary disorders, and genetic and pharmacologic modulation of galectin-3 has therapeutic effects on the treatment of pulmonary illnesses. In this review, we summarize the structure and function of galectin-3 and the underlying mechanisms of galectin-3 in pulmonary disease pathologies; we also discuss preclinical and clinical evidence regarding the therapeutic potential of galectin-3 inhibitors in these pulmonary disorders. Additionally, targeting galectin-3 may be a very promising therapeutic approach for the treatment of pulmonary diseases.

Novel hypoxia-induced HIF-1αactivation in asthma pathogenesis

BACKGROUND

Asthma's complexity, marked by airway inflammation and remodeling, is influenced by hypoxic conditions. This study focuses on the role of Hypoxia-Inducible Factor-1 Alpha (HIF-1α) and P53 ubiquitination in asthma exacerbation.

METHODS

High-throughput sequencing and bioinformatics were used to identify genes associated with asthma progression, with an emphasis on GO and KEGG pathway analyses. An asthma mouse model was developed, and airway smooth muscle cells (ASMCs) were isolated to create an in vitro hypoxia model. Cell viability, proliferation, migration, and apoptosis were assessed, along with ELISA and Hematoxylin and Eosin (H&E) staining.

RESULTS

A notable increase in HIF-1α was observed in both in vivo and in vitro asthma models. HIF-1α upregulation enhanced ASMCs' viability, proliferation, and migration, while reducing apoptosis, primarily via the promotion of P53 ubiquitination through MDM2. In vivo studies showed increased inflammatory cell infiltration and airway structural changes, which were mitigated by the inhibitor IDF-11,774.

CONCLUSION

The study highlights the critical role of the HIF-1α-MDM2-P53 axis in asthma, suggesting its potential as a target for therapeutic interventions. The findings indicate that modulating this pathway could offer new avenues for treating the complex respiratory disorder of asthma.

FOXK2 facilitates the airway remodeling during chronic asthma by promoting glycolysis in a SIRT2-dependent manner

Asthma is a chronic pulmonary disease with the worldwide prevalence. The structural alterations of airway walls, termed as "airway remodeling", are documented as the core contributor to the airway dysfunction during chronic asthma. Forkhead box transcription factor FOXK2 is a critical regulator of glycolysis, a metabolic reprogramming pathway linked to pulmonary fibrosis. However, the role of FOXK2 in asthma waits further explored. In this study, the chronic asthmatic mice were induced via ovalbumin (OVA) sensitization and repetitive OVA challenge. FOXK2 was upregulated in the lungs of OVA mice and downregulated after adenovirus-mediated FOXK2 silencing. The lung inflammation, peribronchial collagen deposition, and glycolysis in OVA mice were obviously attenuated after FOXK2 knockdown. Besides, the expressions of FOXK2 and SIRT2 in human bronchial epithelial cells (BEAS-2B) were increasingly upregulated upon TGF-β1 stimulation and downregulated after FOXK2 knockdown. Moreover, the functional loss of FOXK2 remarkably suppressed TGF-β1-induced epithelial-mesenchymal transition (EMT) and glycolysis in BEAS-2B cells, as manifested by the altered expressions of EMT markers and glycolysis enzymes. The glycolysis inhibitor 2-deoxy-d-glucose (2-DG) inhibited the EMT in TGF-β1-induced cells, making glycolysis a driver of EMT. The binding of FOXK2 to SIRT2 was validated, and SIRT2 overexpression blocked the FOXK2 knockdown-mediated inhibition of EMT and glycolysis in TGF-β1-treated cells, which suggests that FOXK2 regulates EMT and glycolysis in TGF-β1-treated cells in a SIRT2-dependnet manner. Collectively, this study highlights the protective effect of FOXK2 knockdown on airway remodeling during chronic asthma.

LincR-PPP2R5C Deficiency Alleviates Airway Remodeling by Inhibiting Epithelial-Mesenchymal Transition Through the PP2A/TGF-β1 Signaling Pathway in Chronic Experimental Allergic Asthma

Airway remodeling is a key characteristic of allergic asthma. Epithelial-mesenchymal transition (EMT) induced by various factors, particularly transforming growth factor (TGF)-β1, orchestrates airway remodeling. Protein phosphatase 2A (PP2A), an important serine-threonine phosphatase, is involved in TGF-β1 production and EMT. Long noncoding RNAs (lncRNAs) have emerged as novel players in regulating EMT. Here, we aimed to explore the effects and mechanisms of action of lincR-PPP2R5C, a lncRNA that affects PP2A activity, on airway remodeling in a mouse model of chronic allergic asthma. LincR-PPP2R5C knockout (KO) alleviated inflammatory responses in house dust mite (HDM)-induced chronic allergic asthma. Moreover, airway remodeling and EMT were reduced in lung tissues of lincR-PPP2R5C KO mice. HDM extract induced EMT in airway epithelial cells, which was decreased following lincR-PPP2R5C KO. Mechanistically, lincR-PPP2R5C deficiency enhanced PP2A activity, which inhibited TGF-β1 production in epithelial cells. In conclusion, lincR-PPP2R5C deficiency prevented HDM-induced airway remodeling in mice by reversing EMT, which was mediated by the PP2A/TGF-β1 signaling pathway. Thus, lncRNAs, i.e., lincR-PPP2R5C, may be potential targets to prevent airway remodeling in allergic asthma.

Epithelial-Mesenchymal Transition in Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is characterized by prolonged inflammation of the nasal and paranasal sinus mucosa lasting over 12 weeks. CRS is divided into two main types based on the presence of nasal polyps: CRS without nasal polyps and CRS with nasal polyps. The condition is further classified into endotypes based on type 1, type 2, and type 3 inflammatory signatures, with differences in terms of disease severity, prognosis, and treatment response. Recent studies have emphasized the importance of the epithelial-mesenchymal transition (EMT) in CRS progression. In CRS, the EMT can be triggered by infections, allergens, hypoxia, and environmental pollutants. Specifically, EMT induction proceeds through the following mechanisms: viral and bacterial infections disrupt the epithelial barrier, house dust mites and other allergens activate the TGF-β and EGFR signaling pathways, hypoxia increases HIF-1α and other mesenchymal markers, and diesel exhaust particles and particulate matter cause oxidative stress. Maintaining the integrity of the epithelial barrier is essential for nasal mucosa homeostasis. In CRS, barrier damage activates repair processes that trigger the EMT, resulting in barrier dysfunction and tissue remodeling. Epithelial barrier dysfunction allows antigens and pathogens to penetrate, perpetuating inflammation and promoting the EMT. This disruption is a hallmark of CRS, emphasizing the importance of barrier integrity in the development of the disease. Key signaling pathways regulating the EMT in CRS include TGF-β, Wnt, HMGB1, AGE/ERK, TNF-α, and various miRNAs. These signaling pathways connect to various downstream pathways, such as the Smad2/3, GSK-3β/β-catenin, RAGE, and NF-κB pathways. This review focuses on the complex mechanisms of the EMT in CRS, emphasizing the role of epithelial barrier dysfunction and subsequent EMT processes in driving the disease's development and progression. A deeper understanding of these EMT-driven mechanisms will help identify the potential therapeutic targets aimed at restoring epithelial integrity and reversing the EMT.

Wnt5a-mediated autophagy contributes to the epithelial-mesenchymal transition of human bronchial epithelial cells during asthma

BACKGROUND

The epithelial-mesenchymal transition (EMT) of human bronchial epithelial cells (HBECs) is essential for airway remodeling during asthma. Wnt5a has been implicated in various lung diseases, while its role in the EMT of HBECs during asthma is yet to be determined. This study sought to define whether Wnt5a initiated EMT, leading to airway remodeling through the induction of autophagy in HBECs.

METHODS

Microarray analysis was used to investigate the expression change of WNT5A in asthma patients. In parallel, EMT models were induced using 16HBE cells by exposing them to house dust mites (HDM) or interleukin-4 (IL-4), and then the expression of Wnt5a was observed. Using in vitro gain- and loss-of-function approaches via Wnt5a mimic peptide FOXY5 and Wnt5a inhibitor BOX5, the alterations in the expression of the epithelial marker E-cadherin and the mesenchymal marker protein were observed. Mechanistically, the Ca2+/CaMKII signaling pathway and autophagy were evaluated. An autophagy inhibitor 3-MA was used to examine Wnt5a in the regulation of autophagy during EMT. Furthermore, we used a CaMKII inhibitor KN-93 to determine whether Wnt5a induced autophagy overactivation and EMT via the Ca2+/CaMKII signaling pathway.

RESULTS

Asthma patients exhibited a significant increase in the gene expression of WNT5A compared to the healthy control. Upon HDM and IL-4 treatments, we observed that Wnt5a gene and protein expression levels were significantly increased in 16HBE cells. Interestingly, Wnt5a mimic peptide FOXY5 significantly inhibited E-cadherin and upregulated α-SMA, Collagen I, and autophagy marker proteins (Beclin1 and LC3-II). Rhodamine-phalloidin staining showed that FOXY5 resulted in a rearrangement of the cytoskeleton and an increase in the quantity of stress fibers in 16HBE cells. Importantly, blocking Wnt5a with BOX5 significantly inhibited autophagy and EMT induced by IL-4 in 16HBE cells. Mechanistically, autophagy inhibitor 3-MA and CaMKII inhibitor KN-93 reduced the EMT of 16HBE cells caused by FOXY5, as well as the increase in stress fibers, cell adhesion, and autophagy.

CONCLUSION

This study illustrates a new link in the Wnt5a-Ca2+/CaMKII-autophagy axis to triggering airway remodeling. Our findings may provide novel strategies for the treatment of EMT-related diseases.

β-Tocotrienol Decreases PDGF-BB-Induced Proliferation and Migration of Human Airway Smooth Muscle Cells by Inhibiting RhoA and Reducing ROS Production

BACKGROUND

Tocotrienols exhibit antioxidant and anti-inflammatory activities. RhoA, a small GTPase protein, plays a crucial role in regulating contractility in airway smooth muscle (ASM). Previous studies have demonstrated that γ-tocotrienols reduce ASM proliferation and migration by inhibiting the activation of RhoA. In this present study, we investigate the effect of another vitamin E isoform, β-tocotrienols, on human ASM cell proliferation and migration stimulated by platelet-derived growth factor-BB (PDGF-BB).

METHODS

Human ASM cells were pre-treated with β-tocotrienol prior to being stimulated with PDGF-BB to induce ASM cell proliferation and migration. The proliferation and migration of PDGF-BB-induced human ASM cells were assessed using colorimetric and transwell migration assays. The intracellular ROS assay kit was employed to quantify reactive oxygen species (ROS) in human ASM cells. Additionally, we explored the effect of β-tocotrienols on the signaling pathways involved in PDGF-BB-induced ASM proliferation and migration.

RESULTS

β-tocotrienol inhibited PDGF-BB-induced ASM cell proliferation and migration by reducing RhoA activation and ROS production. However, in this present study, β-tocotrienol did not affect the signaling pathways associated with cyclin D1, phosphorylated Akt1, and ERK1/2.

CONCLUSIONS

In conclusion, the inhibition of RhoA activation and ROS production by β-tocotrienol, resulting in the reduction in human ASM proliferation and migration, suggests its potential as a treatment for asthma airway remodeling.

The New Paradigm: The Role of Proteins and Triggers in the Evolution of Allergic Asthma

Epithelial barrier damage plays a central role in the development and maintenance of allergic inflammation. Rises in the epithelial barrier permeability of airways alter tissue homeostasis and allow the penetration of allergens and other external agents. Different factors contribute to barrier impairment, such as eosinophilic infiltration and allergen protease action-eosinophilic cationic proteins' effects and allergens' proteolytic activity both contribute significantly to epithelial damage. In the airways, allergen proteases degrade the epithelial junctional proteins, allowing allergen penetration and its uptake by dendritic cells. This increase in allergen-immune system interaction induces the release of alarmins and the activation of type 2 inflammatory pathways, causing or worsening the main symptoms at the skin, bowel, and respiratory levels. We aim to highlight the molecular mechanisms underlying allergenic protease-induced epithelial barrier damage and the role of immune response in allergic asthma onset, maintenance, and progression. Moreover, we will explore potential clinical and radiological biomarkers of airway remodeling in allergic asthma patients.

Single-cell omics identifies inflammatory signaling as a trans-differentiation trigger in mouse embryos

Trans-differentiation represents a direct lineage conversion; however, insufficient characterization of this process hinders its potential applications. Here, to explore a potential universal principal for trans-differentiation, we performed single-cell transcriptomic analysis of endothelial-to-hematopoietic transition (EHT), endothelial-to-mesenchymal transition, and epithelial-to-mesenchymal transition in mouse embryos. We applied three scoring indexes of entropies, cell-type signature transcription factor expression, and critical transition signals to show common features underpinning the fate plasticity of transition states. Cross-model comparison identified inflammatory-featured transition states and a common trigger role of interleukin-33 in promoting fate conversions. Multimodal profiling (integrative transcriptomic and chromatin accessibility analysis) demonstrated the inflammatory regulation of hematopoietic specification. Furthermore, multimodal omics and fate-mapping analyses showed that endothelium-specific Spi1, as an inflammatory effector, governs appropriate chromatin accessibility and transcriptional programs to safeguard EHT. Overall, our study employs single-cell omics to identify critical transition states/signals and the common trigger role of inflammatory signaling in developmental-stress-induced fate conversions.

Circ_0070934 promotes MGAT3 expression and inhibits epithelial-mesenchymal transition in bronchial epithelial cells by sponging miR-199a-5p

BACKGROUND

Circular RNA (circRNA) has the potential to serve as a crucial regulator in the progression of bronchial asthma. The objective of this investigation was to elucidate the functional dynamics of the circ_0070934/miR-199a-5p/Mannoside acetylglucosaminyltransferase 3 (MGAT3) axis in the development of asthma.

METHODS

Circ_0070934, miR-199a-5p and MGAT3 in peripheral venous blood of 38 asthmatic patients and 43 healthy controls were detected by qRT-PCR, and the expression of MGAT3 protein was examined by ELISA. The GSE148000 dataset was analyzed for differences in MGAT3. The BEAS-2B cells were transfected with circ_0070934 plasmid and small interfering RNA, miR-199a-5p mimics and inhibitors. The apoptosis level was detected by flow cytometry and MGAT3 was detected by qRT-PCR and Western blot. The expression of E-cadherin, N-cadherin, Vimentin was examined by Western blot. Interleukin-4 (IL-4) and IL-13 were used to co-stimulate BEAS-2B cells as an asthmatic airway epithelial cell model. BEAS-2B cells exposed to type 2 cytokines (IL-4 and IL-13) were treated with circ_0070934 plasmid, and the expression of E-cadherin, N-cadherin, and Vimentin was detected by Western blot. The binding relationships were verified using dual-luciferase reporter assay and miRNA pull-down assay.

RESULTS

The expression of circ_0070934 and MGAT3 in peripheral venous blood of asthmatic patients was down-regulated, and the expression of miR-199a-5p was up-regulated. And the expression of MGAT3 was reduced in sputum of asthma patients. Down-regulating the expression of circ_0070934 could promote apoptosis of BEAS-2B cells and increase epithelial-mesenchymal transition (EMT), and this effect can be partially reversed by down-regulating miR-199a-5p. Circ_0070934 could inhibit the process of epithelial mesenchymal transition induced by IL-4 and IL-13 in BEAS-2B cells. In addition, miR-199a-5p could respectively bind to circ_0070934 and MGAT3.

CONCLUSION

The findings of this study indicate that circ_0070934 may function as a competitive endogenous RNA (ceRNA) of miR-199a-5p, thereby modulating the expression of MGAT3 and impacting the process of EMT in bronchial epithelial cells. These results contribute to the establishment of a theoretical framework for advancing the prevention and treatment strategies for asthma.

Plasma sCD146 is a potential biomarker for acute exacerbation of chronic obstructive pulmonary disease

This study examined the levels of soluble CD146 (sCD146) in plasma samples from patients with chronic obstructive pulmonary disease (COPD) and assessed the relationship between sCD146 and the severity of COPD. A total of 97 COPD patients were recruited from 20 medical centers in Jiangsu, China, including 13 stable subjects and 84 exacerbated subjects. The plasma sCD146 level in exacerbated subjects (28.77 ± 10.80 ng/mL) was significantly lower than that in stable subjects (38.84 ± 15.00 ng/mL). In the high sCD146 group, the proportion of subjects with modified Medical Research Council (mMRC) scores of 0-1 was higher, the proportion of subjects with the Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 4 was lower, and the proportion of subjects with ≥1 hospitalizations in the past year was lower. The plasma sCD146 level was negatively correlated with the COPD Assessment Test (CAT) score (r = -0.2664, p = 0.0087). Logistic regression analysis showed that sCD146 was an independent risk factor for acute exacerbation of COPD (AECOPD). Receiver operating characteristic (ROC) analysis suggested that sCD146 combined with sex, age, pulmonary function, and acute exacerbations in the past year had clinical value for the accurate identification of AECOPD, with an area under the ROC curve (AUC) of 0.908 (95% CI: 0.810-1.000, p < 0.001). In addition, there was a significant negative correlation between plasma sCD146 and S100A9 (r = -0.3939, p < 0.001).

Biomaterial-based mechanical regulation facilitates scarless wound healing with functional skin appendage regeneration

Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages, ultimately impairing its normal physiological function. Accumulating evidence underscores the potential of targeted modulation of mechanical cues to enhance skin regeneration, promoting scarless repair by influencing the extracellular microenvironment and driving the phenotypic transitions. The field of skin repair and skin appendage regeneration has witnessed remarkable advancements in the utilization of biomaterials with distinct physical properties. However, a comprehensive understanding of the underlying mechanisms remains somewhat elusive, limiting the broader application of these innovations. In this review, we present two promising biomaterial-based mechanical approaches aimed at bolstering the regenerative capacity of compromised skin. The first approach involves leveraging biomaterials with specific biophysical properties to create an optimal scarless environment that supports cellular activities essential for regeneration. The second approach centers on harnessing mechanical forces exerted by biomaterials to enhance cellular plasticity, facilitating efficient cellular reprogramming and, consequently, promoting the regeneration of skin appendages. In summary, the manipulation of mechanical cues using biomaterial-based strategies holds significant promise as a supplementary approach for achieving scarless wound healing, coupled with the restoration of multiple skin appendage functions.

Armeniacae semen amarum: a review on its botany, phytochemistry, pharmacology, clinical application, toxicology and pharmacokinetics

Armeniacae semen amarum-seeds of Prunus armeniaca L. (Rosaceae) (ASA), also known as Kuxingren in Chinese, is a traditional Chinese herbal drug commonly used for lung disease and intestinal disorders. It has long been used to treat coughs and asthma, as well as to lubricate the colon and reduce constipation. ASA refers to the dried ripe seed of diverse species of Rosaceae and contains a variety of phytochemical components, including glycosides, organic acids, amino acids, flavonoids, terpenes, phytosterols, phenylpropanoids, and other components. Extensive data shows that ASA exhibits various pharmacological activities, such as anticancer activity, anti-oxidation, antimicrobial activity, anti-inflammation, protection of cardiovascular, neural, respiratory and digestive systems, antidiabetic effects, and protection of the liver and kidney, and other activities. In clinical practice, ASA can be used as a single drug or in combination with other traditional Chinese medicines, forming ASA-containing formulas, to treat various afflictions. However, it is important to consider the potential adverse reactions and pharmacokinetic properties of ASA during its clinical use. Overall, with various bioactive components, diversified pharmacological actions and potent efficacies, ASA is a promising drug that merits in-depth study on its functional mechanisms to facilitate its clinical application.

Long non-coding RNA (LncRNA) non-coding RNA activated by DNA damage (NORAD) knockdown alleviates airway remodeling in asthma via regulating miR-410-3p/RCC2 and inhibiting Wnt/β-catenin pathway

Background

Asthma is a chronic inflammatory disorder with high prevalence in childhood. Airway remodeling, an important structural change of the airways, is resulted from epithelial-mesenchymal transition. Long non-coding RNA non-coding RNA activated by DNA damage (NORAD) has been found to promote epithelial-mesenchymal transition in multiple cancers. This study aimed to analyze the role of NORAD in asthma, mainly focusing on epithelial-mesenchymal transition-mediated airway remodeling, and further explored the NORAD-miRNA-mRNA network.

Methods

NORAD expression was analyzed in transforming growth factor-β1-induced BEAS-2B human bronchial epithelial cells and ovalbumin-challenged asthmatic mice. The influences of NORAD on the epithelial-mesenchymal transition characteristics and Wnt/β-catenin pathway activation were analyzed in vitro. The interactions between NORAD and miR-410-3p as well as miR-410-3p and regulator of chromosome condensation 2 were detected by dual-luciferase reporter assay and RNA pull-down assay. Rescue experiments using miR-410-3p antagonist and chromosome condensation 2 overexpression were used to confirm the mechanism of NORAD. Additionally, the role and mechanism of NORAD were further evaluated in asthmatic mice.

Results

NORAD expression was elevated in both asthmatic models. Knockdown of NORAD impeded spindle-like morphology changes, elevated E-cadherin expression, decreased N-cadherin expression, suppressed cell migration, and inactivated the Wnt/β-catenin pathway in transforming growth factor-β1-stimulated BEAS-2B cells. NORAD acted as a sponge of miR-410-3p to regulate chromosome condensation 2 expression. Rescue assays demonstrated that silencing of NORAD ameliorated transforming growth factor-β1-induced EMT via miR-410-3p/chromosome condensation 2/Wnt/β-catenin axis. In vivo, knockdown of NORAD led to the reduction of inflammatory cell infiltration and collagen deposition, suppression of IL-4, IL-13, transforming growth factor-β1 and immunoglobulin E production, decreasing of N-cadherin, chromosome condensation 2, β-catenin and c-Myc expression, but increasing of E-cadherin and miR-410-3p expression.

Conclusions

Silencing of NORAD alleviated epithelial-mesenchymal transition-mediated airway remodeling in asthma via mediating miR-410-3p/chromosome condensation 2/Wnt/β-catenin pathway.

IL-1β and iNOS can drive the asthmatic comorbidities and decrease of lung function in perennial allergic rhinitis children

BACKGROUND

Allergic asthma and rhinitis (AR) are closely linked, with a significant proportion of AR patients developing asthma. Identification of the early signs of comorbidity of AR and asthma can enable prompt treatment and prevent asthma progression.

OBJECTIVES AND METHODS

This study investigated the role of interleukin-1β (IL-1β), a pro-inflammatory cytokine, and inducible nitric oxide synthase (iNOS) in the comorbidity of AR and asthma and lung function in Korean children with perennial AR (PAR). A cohort of 240 subjects (6 to 10 years old) with PAR (PAR alone: 113 children, PAR and asthma: 127 children) was analyzed for various biomarkers, including IL-1β, iNOS, and epithelial-mesenchymal transition (EMT) markers in serum. The blood levels of eosinophils and immunoglobulin E (IgE) were examined. IL-1β, CCL-24, E-cadherin, and vimentin were measured by enzyme-linked immunosorbent assay (ELISA). Epithelial iNOS was measured by the NOS kit.

RESULTS

Elevated levels of IL-1β, iNOS, and vimentin in the serum were identified as significant indicators of the likelihood of comorbidity of PAR and asthma in children. Furthermore, higher concentrations of IL-1β, iNOS, and vimentin have been linked to reduced lung function in PAR children. Notably, IL-1β expression shows a relationship with the levels of E-cadherin, vimentin, and CCL-24. However, no correlation was found between IL-1β and iNOS expressions.

CONCLUSIONS

This study suggests that IL-1β and iNOS can be biomarkers in the progression of PAR and asthma and decreased lung function, suggesting potential targets for early intervention and treatment.

Cytokines as drivers: Unraveling the mechanisms of epithelial-mesenchymal transition in COVID-19 lung fibrosis

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), like other viruses, can induce proliferation of myofibroblasts and even lead to fibrosis in the lung. Epithelial-mesenchymal transition (EMT) is thought to play an essential role in the pathogenesis of Coronavirus disease 19 (COVID-19). EMT is originally a critical process that regulates the development of different tissues in the embryo, but in inflammatory situations, EMT tries to be activated again to control inflammation or even heal inflammatory damage. However, in pathological situations, such as chronic viral infections (e.g., COVID-19) or pulmonary fibrosis initiation, this benign healing transforms into sinister nature, pushing the lung into the fibrotic process. Notably, the cytokines released by inflammatory cells and the chronic inflammatory microenvironment shared by fibrotic cells promote each other as critical factors in the induction of pathological EMT. In the induction of SARS-CoV-2 virus, cytokines are an essential mediator of EMT transformation, and a summary of whether COVID-19 patients, during the infection phase, have many persistent inflammatory mediators (cytokines) that are a causative factor of EMT has not yet appeared. The following common signaling drivers, including Transforming growth factor beta (TGF-β), cytokines, Notch signaling pathway, Wnt and hypoxia signaling pathways, drive the regulation of EMT. In this review, we will focus on 3 key EMT signaling pathways: TGF-β, Leucine zipper transcription factor like 1 (LZTFL1) and the common interleukin family expressed in the lung. TGF-β-induced SNAIL and LZTFL1 were identified as regulatory EMT in COVID-19. For cytokines, the interleukin family is a common inducer of EMT and plays an essential role in the formation of the microenvironment of fibrosis. We sought to demonstrate that cytokines act as "communicators" and build the "microenvironment" of fibrosis together with EMT as a "bridge" to induce EMT in fibrosis. The mechanisms utilized by these two pathways could serve as templates for other mesenchymal transformations and provide new potential therapeutic targets.

m6A-modified miR-143-3p inhibits epithelial mesenchymal transition in bronchial epithelial cells and extracellular matrix production in lung fibroblasts by targeting Smad3

BACKGROUND

Airway epithelial cells epithelial mesenchymal transition (EMT) and lung fibroblasts extracellular matrix (ECM) production are the key steps in airway remodeling. Our previous study demonstrated that miR-143-3p has the ability to impede airway smooth muscle cell proliferation and ECM deposition. However, the function of miR-143-3p in airway epithelial cells and lung fibroblasts remains unclear.

METHODS

Cell viability was determined using MTT method, while cell migration was evaluated through scratch assay. EMT and ECM proteins were detected by western blot, RT-qPCR, and ELISA. To determine the level of miR-143-3p m6A methylation, we employed the meRIP-qPCR assay. Additionally, the binding of miR-143-3p with Smad3 were projected by bioinformatics and validated by dual luciferase reporter assays.

RESULTS

It was discovered that the expression of miR-143-3p were lower in both asthma patients and TGF-β1-treated human bronchial epithelial 16HBE cells and human lung fibroblast HPF cells. Upregulation of miR-143-3p restrained 16HBE cell migration, and decreased EMT mesenchymal markers and increased epithelial markers. And upregulation of miR-143-3p impaired cell viability and ECM protein production in HPF cells. Mechanistically, interfering with METTL3 resulted in decreased m6A modification of miR-143-3p and led to lower levels of miR-143-3p. Moreover, miR-143-3p were verified to directly target and downregulate Smad3. Upregulation of Smad3 attenuated the effects of miR-143-3p on cell EMT and ECM production.

CONCLUSION

MiR-143-3p inhibits airway epithelial cell EMT as well as lung fibroblast ECM production by downregulating Smad3. Therefore, miR-143-3p may be a promising target to reduce airway remodeling in asthma.

Semaphorin 7a aggravates TGF-β1-induced airway EMT through the FAK/ERK1/2 signaling pathway in asthma

Background

TGF-β1 can induce epithelial-mesenchymal transition (EMT) in primary airway epithelial cells (AECs). Semaphorin7A (Sema7a) plays a crucial role in regulating immune responses and initiating and maintaining transforming growth factor β1 TGF-β1-induced fibrosis.

Objective

To determine the expression of Sema7a, in serum isolated from asthmatics and non-asthmatics, the role of Sema7a in TGF-β1 induced proliferation, migration and airway EMT in human bronchial epithelial cells (HBECs) in vitro.

Methods

The concentrations of Sema7a in serum of asthmatic patients was detected by enzyme-linked immunosorbent assay (ELISA). The expressions of Sema7a and integrin-β1 were examined using conventional western blotting and real-time quantitative PCR (RT-PCR). Interaction between the Sema7a and Integrin-β1 was detected using the Integrin-β1 blocking antibody (GLPG0187). The changes in EMT indicators were performed by western blotting and immunofluorescence, as well as the expression levels of phosphorylated Focal-adhesion kinase (FAK) and Extracellular-signal-regulated kinase1/2 (ERK1/2) were analyzed by western blot and their mRNA expression was determined by RT-PCR.

Results

We described the first differentially expressed protein of sema7a, in patients with diagnosed bronchial asthma were significantly higher than those of healthy persons (P<0.05). Western blotting and RT-PCR showed that Sema7a and Integrin-β1 expression were significantly increased in lung tissue from the ovalbumin (OVA)-induced asthma model. GLPG0187 inhibited TGF-β1-mediated HBECs EMT, proliferation and migration, which was associated with Focal-adhesion kinase (FAK) and Extracellular-signal-regulated kinase1/2 (ERK1/2) phosphorylation.

Conclusion

Sema7a may play an important role in asthma airway remodeling by inducing EMT. Therefore, new therapeutic approaches for the treatment of chronic asthma, could be aided by the development of agents that target the Sema7a.

Research progress on the mechanism of astragaloside IV in the treatment of asthma

Asthma is a common chronic respiratory disease, and its treatment is a core problem and challenge in clinical practice. Glucocorticoids (GCs) are the first-line therapy for the treatment of asthma. Local and systemic adverse reactions caused by GCs create obstacles to the treatment of asthma. Therefore, the research target is to find a new, safe, and effective therapeutic medicine at present. Natural products are an important source for treating asthma with low cost and low toxicity. Astragaloside IV (AS-IV) is an active ingredient of traditional Chinese medicine Astragalus mongholicus Bunge. Previous studies have indicated that AS-IV plays a therapeutic role in the treatment of asthma by inhibiting airway inflammation and remodeling the airway, and by regulating immunity and neuroendocrine function (Fig. 1) . It has a variety of biological characteristics such as multi-target intervention, high safety, and good curative effect. This article reviews the specific mechanism of AS-IV for the treatment of asthma to provide references for subsequent research.

Eosinophils and tissue remodeling: Relevance to airway disease

The ability of human tissue to reorganize and restore its existing structure underlies tissue homeostasis in the healthy airways, but in disease can persist without normal resolution, leading to an altered airway structure. Eosinophils play a cardinal role in airway remodeling both in health and disease, driving epithelial homeostasis and extracellular matrix turnover. Physiological consequences associated with eosinophil-driven remodeling include impaired lung function and reduced bronchodilator reversibility in asthma, and obstructed airflow in chronic rhinosinusitis with nasal polyps. Given the contribution of airway remodeling to the development and persistence of symptoms in airways disease, targeting remodeling is an important therapeutic consideration. Indeed, there is early evidence that eosinophil attenuation may reduce remodeling and disease progression in asthma. This review provides an overview of tissue remodeling in both health and airway disease with a particular focus on eosinophilic asthma and chronic rhinosinusitis with nasal polyps, as well as the role of eosinophils in these processes and the implications for therapeutic interventions. Areas for future research are also noted, to help improve our understanding of the homeostatic and pathological roles of eosinophils in tissue remodeling, which should aid the development of targeted and effective treatments for eosinophilic diseases of the airways.

CD146 deficiency promotes inflammatory type 2 responses in pulmonary cryptococcosis

Cryptococcus neoformans (C. neoformans) is an important opportunistic fungal pathogen for pulmonary cryptococcosis. Previously, we demonstrated that CD146 mediated the adhesion of C. neoformans to the airway epithelium. CD146 is more than an adhesion molecule. In the present study, we aimed to explore the roles of CD146 in the inflammatory response in pulmonary cryptococcosis. CD146 was decreased in lung tissues from patients with pulmonary cryptococcosis. Similarly, C. neoformans reduced pulmonary CD146 expression in mice following intratracheal inoculation. To explore the pathological roles of CD146 reduction in pulmonary cryptococcosis, CD146 knockout (KO) mice were inoculated with C. neoformans via intratracheal instillation. CD146 deficiency aggravated C. neoformans infection, as evidenced by a shortened survival time and increased fungal burdens in the lung. Inflammatory type 2 cytokines (IL-4, IL-5, and TNF-α) and alternatively activated macrophages were increased in the pulmonary tissues of CD146 KO-infected mice. CD146 is expressed in immune cells (macrophages, etc.) and nonimmune cells, i.e., epithelial cells and endothelial cells. Bone marrow chimeric mice were established and infected with C. neoformans. CD146 deficiency in immune cells but not in nonimmune cells increased fungal burdens in the lung. Mechanistically, upon C. neoformans challenge, CD146 KO macrophages produced more neutrophil chemokine KC and inflammatory cytokine TNF-α. Meanwhile, CD146 KO macrophages decreased the fungicidity and production of reactive oxygen species. Collectively, C. neoformans infection decreased CD146 in pulmonary tissues, leading to inflammatory type 2 responses, while CD146 deficiency worsened pulmonary cryptococcosis.

Rhinovirus induces airway remodeling: what are the physiological consequences?

BACKGROUND

Rhinovirus infections commonly evoke asthma exacerbations in children and adults. Recurrent asthma exacerbations are associated with injury-repair responses in the airways that collectively contribute to airway remodeling. The physiological consequences of airway remodeling can manifest as irreversible airway obstruction and diminished responsiveness to bronchodilators. Structural cells of the airway, including epithelial cells, smooth muscle, fibroblasts, myofibroblasts, and adjacent lung vascular endothelial cells represent an understudied and emerging source of cellular and extracellular soluble mediators and matrix components that contribute to airway remodeling in a rhinovirus-evoked inflammatory environment.

MAIN BODY

While mechanistic pathways associated with rhinovirus-induced airway remodeling are still not fully characterized, infected airway epithelial cells robustly produce type 2 cytokines and chemokines, as well as pro-angiogenic and fibroblast activating factors that act in a paracrine manner on neighboring airway cells to stimulate remodeling responses. Morphological transformation of structural cells in response to rhinovirus promotes remodeling phenotypes including induction of mucus hypersecretion, epithelial-to-mesenchymal transition, and fibroblast-to-myofibroblast transdifferentiation. Rhinovirus exposure elicits airway hyperresponsiveness contributing to irreversible airway obstruction. This obstruction can occur as a consequence of sub-epithelial thickening mediated by smooth muscle migration and myofibroblast activity, or through independent mechanisms mediated by modulation of the β2 agonist receptor activation and its responsiveness to bronchodilators. Differential cellular responses emerge in response to rhinovirus infection that predispose asthmatic individuals to persistent signatures of airway remodeling, including exaggerated type 2 inflammation, enhanced extracellular matrix deposition, and robust production of pro-angiogenic mediators.

CONCLUSIONS

Few therapies address symptoms of rhinovirus-induced airway remodeling, though understanding the contribution of structural cells to these processes may elucidate future translational targets to alleviate symptoms of rhinovirus-induced exacerbations.

The Role of Epithelial Mesenchymal Transition (EMT) in Pathogenesis of Cardiotoxicity: Diagnostic & Prognostic Approach

Cancer is one of the diseases, which it is not still completely curable; the existing treatments are associated with many complications, that double its complexity. One of the causes of cancer cell metastasis is Epithelial Mesenchymal Transition (EMT). Recently study demonstrated that EMT cause cardiotoxicity and heart diseases such as heart failure, hypertrophy and fibrosis. This study evaluated molecular and signaling pathway, which lead to cardiotoxicity via EMT. It was demonstrated that the processes of inflammation, oxidative stress and angiogenesis were involved in EMT and cardiotoxicity. The pathways related to these processes act as a double-edged sword. In relation to inflammation and oxidative stress, molecular pathways caused apoptosis of cardiomyocytes and cardiotoxicity induction. While the angiogenesis process inhibits cardiotoxicity despite the progression of EMT. On the other hand, some molecular pathways such as PI3K/mTOR despite causing the progression of EMT lead to the proliferation of cardiomyocytes and prevent cardiotoxicity. Therefore, it was concluded that the identification of molecular pathways can help in designing therapeutic and preventive strategies to increase patients' survival.

Pulmonary inflammation and fibroblast immunoregulation: from bench to bedside

In recent years, there has been an explosion of interest in how fibroblasts initiate, sustain, and resolve inflammation across disease states. Fibroblasts contain heterogeneous subsets with diverse functionality. The phenotypes of these populations vary depending on their spatial distribution within the tissue and the immunopathologic cues contributing to disease progression. In addition to their roles in structurally supporting organs and remodeling tissue, fibroblasts mediate critical interactions with diverse immune cells. These interactions have important implications for defining mechanisms of disease and identifying potential therapeutic targets. Fibroblasts in the respiratory tract, in particular, determine the severity and outcome of numerous acute and chronic lung diseases, including asthma, chronic obstructive pulmonary disease, acute respiratory distress syndrome, and idiopathic pulmonary fibrosis. Here, we review recent studies defining the spatiotemporal identity of the lung-derived fibroblasts and the mechanisms by which these subsets regulate immune responses to insult exposures and highlight past, current, and future therapeutic targets with relevance to fibroblast biology in the context of acute and chronic human respiratory diseases. This perspective highlights the importance of tissue context in defining fibroblast-immune crosstalk and paves the way for identifying therapeutic approaches to benefit patients with acute and chronic pulmonary disorders.

A novel anti-IL-33 antibody recognizes an epitope FVLHN of IL-33 and has a therapeutic effect on inflammatory diseases

As a crucial member of the Interleukin-1 (IL-1) family, IL-33 plays an indispensable role in modulating inflammatory responses. Here, we developed an effective anti-human IL-33 monoclonal antibody (mAb) named 5H8. Importantly, we have identified an epitope (FVLHN) of IL-33 protein as a recognition sequence for 5H8, which plays an important role in mediating the biological activity of IL-33. We observed that 5H8 significantly suppressed IL-33-induced IL-6 expression in bone marrow cells and mast cells in a dose-dependent manner in vitro. Furthermore, 5H8 effectively relievedHDM-induced asthma and PR8-induced acute lung injury in vivo. These findings indicate that targeting the FVLHN epitope is critical for inhibiting IL-33 function. In addition, wedetected that the Tm value of 5H8 was 66.47℃ and the KD value was 173.0 pM, which reflected that 5H8 had good thermal stability and high affinity. Taken together, our data suggest that our newly developed 5H8 antibody has potential as a therapeutic antibody for treating inflammatory diseases.

Epithelial-Mesenchymal Transition Mechanisms in Chronic Airway Diseases: A Common Process to Target?

Epithelial-to-mesenchymal transition (EMT) is a reversible process, in which epithelial cells lose their epithelial traits and acquire a mesenchymal phenotype. This transformation has been described in different lung diseases, such as lung cancer, interstitial lung diseases, asthma, chronic obstructive pulmonary disease and other muco-obstructive lung diseases, such as cystic fibrosis and non-cystic fibrosis bronchiectasis. The exaggerated chronic inflammation typical of these pulmonary diseases can induce molecular reprogramming with subsequent self-sustaining aberrant and excessive profibrotic tissue repair. Over time this process leads to structural changes with progressive organ dysfunction and lung function impairment. Although having common signalling pathways, specific triggers and regulation mechanisms might be present in each disease. This review aims to describe the various mechanisms associated with fibrotic changes and airway remodelling involved in chronic airway diseases. Having better knowledge of the mechanisms underlying the EMT process may help us to identify specific targets and thus lead to the development of novel therapeutic strategies to prevent or limit the onset of irreversible structural changes.

Epithelial cell dysfunction in chronic rhinosinusitis: the epithelial-mesenchymal transition

INTRODUCTION

Epithelial-mesenchymal transition (EMT) is a type of epithelial cell dysfunction, which is widely present in the nasal mucosa of patients with chronic rhinosinusitis (CRS), especially CRS with nasal polyps, and contributes to pathogenesis of the disease. EMT is mediated via complex mechanisms associated with multiple signaling pathways.

AREAS COVERED

We have summarized the underlying mechanisms and signaling pathways promoting EMT in CRS. Strategies or drugs/agents targeting the genes and pathways related to the regulation of EMT are also discussed for their potential use in the treatment of CRS and asthma. A literature search of studies published in English from 2000 to 2023 was conducted using the PubMed database, employing CRS, EMT, signaling, mechanisms, targeting agents/drugs, as individual or combinations of search terms.

EXPERT OPINION

EMT in nasal epithelium not only leads to epithelial cell dysfunction but also plays an important role in nasal tissue remodeling in CRS. A comprehensive understanding of the mechanisms underlying EMT and the development of drugs/agents targeting these mechanisms may provide new treatment strategies for CRS.

Non-self glycan structures as possible modulators of cancer progression: would polysaccharides from Cryptococcus spp. impact this phenomenon?

Invasive fungal infections (IFI) are responsible for a large number of annual deaths. Most cases are closely related to patients in a state of immunosuppression, as is the case of patients undergoing chemotherapy. Cancer patients are severely affected by the worrisome proportions that an IFI can take during cancer progression, especially in an already immunologically and metabolically impaired patient. There is scarce knowledge about strategies to mitigate cancer progression in these cases, beyond conventional treatment with antifungal drugs with a narrow therapeutic range. However, in recent years, ample evidence has surfaced describing the possible interferences that IFI may have both on the progression of pre-existing cancers and in the induction of newly transformed cells. The leading gambit for modulation of tumor progression comes from the ability of fungal virulence factors to modulate the host's immune system, since they are found in considerable concentrations in the tumor microenvironment during infection. In this context, cryptococcosis is of particular concern, since the main virulence factor of the pathogenic yeast is its polysaccharide capsule, which carries constituents with high immunomodulatory properties and cytotoxic potential. Therefore, we open a discussion on what has already been described regarding the progression of cryptococcosis in the context of cancer progression, and the possible implications that fungal glycan structures may take in both cancer development and progression.

LINC1810064F22Rik sequesters miR-206-5p away from HDAC4 to exacerbate allergic airway inflammation and airway remodeling in an ovalbumin mouse model of asthma

Allergic inflammation and airway remodeling frequently occur in asthma. This study clarifies a novel LINC1810064F22Rik-mediated ceRNA mechanism involved in asthma-induced allergic inflammation and airway remodeling based on bioinformatics analysis and in vivo and in vitro experiments. The differentially expressed lncRNAs and downstream effectors were predicted in silico. The targeting relationship among LINC1810064F22Rik, miR-206-5p, and HDAC4 was predicted by bioinformatics analysis, which was further validated by dual luciferase reporter gene assay. The asthma-like airway inflammation was induced in mice using ovalbumin (OVA) sensitization/challenge with immune adjuvant Al(OH)₃, while alveolar epithelial cells (AECs) were exposed to IL-33 to mimic in vitro inflammatory environment. LINC1810064F22Rik and HDAC4 were highly expressed, while miR-206-5p was poorly expressed in the tracheal tissues of OVA mice and the IL-33-treated AECs. The OVA mice and IL-33-treated AECs were subjected to gain- or loss-of-function experiments to detect the interaction of LINC1810064F22Rik/miR-206-5p/HDAC4 axis and their effects on allergic inflammation and airway remodeling. LINC1810064F22Rik competitively bound to miR-206-5p, and miR-206-5p targeted and inhibited HDAC4. The in vivo animal experiments indicated that LINC1810064F22Rik promoted asthma-induced allergic inflammation and airway remodeling by sequestering miR-206-5p away from HDAC4. The evidence provided by our study highlighted the involvement of the LINC1810064F22Rik/miR-206-5p/HDAC4 axis in facilitating allergic airway inflammation and airway remodeling in OVA mice.

Elevated levels of interleukin-33 are associated with asthma: A meta-analysis

BACKGROUND

Previous studies reported that patients with asthma showed higher levels of interleukin (IL)-33 in peripheral blood, compared to healthy control (HCs). However, we also noticed that there were no significant differences of IL-33 levels between controls and asthma patients in a recent study. We aim to conduct this meta-analysis and evaluate the feasibility of IL-33 in peripheral blood that may act as a promising biomarker in asthma.

METHODS

Articles published before December 2022 were searched in these databases (PubMed, Web of Science, EMBASE, and Google Scholar). We used STATA 12.0 software to compute the results.

RESULTS

The study showed that asthmatics showed higher IL-33 level in serum and plasma, compared to HCs (serum: standard mean difference [SMD] 2.06, 95% confidence interval [CI] 1.12-3.00, I2  = 98.4%, p < .001; plasma: SMD 3.67, 95% CI 2.32-5.03, I2  = 86.0%, p < .001). Subgroup analysis indicated that asthma adults showed higher IL-33 level in serum, compared to HCs, whereas no significant difference in IL-33 level in serum was showed between asthma children and HCs (adults: SMD 2.17, 95% CI 1.09-3.25; children: SMD 1.81, 95% CI -0.11 to 3.74). The study indicated that moderate and severe asthmatics showed higher IL-33 level in serum, compared to mild asthmatics (SMD 0.78, 95% CI 0.41-1.16, I2  = 66.2%, p = .011).

CONCLUSIONS

In conclusion, the main findings of present meta-analysis suggested that there was a significant correlation between IL-33 levels and the severity of asthma. Therefore, IL-33 levels of either serum or plasma may be regarded as a useful biomarker of asthma or the degree of disease.

Extracellular Vesicles (EVs) as Crucial Mediators of Cell-Cell Interaction in Asthma

Asthma is the most common chronic respiratory disorder worldwide and accounts for a huge health and economic burden. Its incidence is rapidly increasing but, in parallel, novel personalized approaches have emerged. Indeed, the improved knowledge of cells and molecules mediating asthma pathogenesis has led to the development of targeted therapies that significantly increased our ability to treat asthma patients, especially in severe stages of disease. In such complex scenarios, extracellular vesicles (EVs i.e., anucleated particles transporting nucleic acids, cytokines, and lipids) have gained the spotlight, being considered key sensors and mediators of the mechanisms controlling cell-to-cell interplay. We will herein first revise the existing evidence, mainly by mechanistic studies in vitro and in animal models, that EV content and release is strongly influenced by the specific triggers of asthma. Current studies indicate that EVs are released by potentially all cell subtypes in the asthmatic airways, particularly by bronchial epithelial cells (with different cargoes in the apical and basolateral side) and inflammatory cells. Such studies largely suggest a pro-inflammatory and pro-remodelling role of EVs, whereas a minority of reports indicate protective effects, particularly by mesenchymal cells. The co-existence of several confounding factors-including technical pitfalls and host and environmental confounders-is still a major challenge in human studies. Technical standardization in isolating EVs from different body fluids and careful selection of patients will provide the basis for obtaining reliable results and extend their application as effective biomarkers in asthma.

lncRNA CRNDE Affects Th17/IL-17A and Inhibits Epithelial-Mesenchymal Transition in Lung Epithelial Cells Reducing Asthma Signs

Background

Asthma treatment is difficult due to disease heterogeneity and comorbidities. In addition, the development of drugs targeting the underlying mechanisms of asthma remains slow. We planned to identify the most upregulated differentially expressed long noncoding RNA in asthma to explore its regulatory patterns and pathways in asthma.

Methods

We sensitized mice using a mixture of ovalbumin, house dust mites, and lipopolysaccharide to establish an asthma mouse model. We also sensitized asthma cells with TGF-β1 in an in vitro model. We performed a microarray analysis to identify the lncRNA with the differential expression level in model mice. We applied hematoxylin and eosin and Masson's trichrome stainings to mouse tissues to quantify the tissue damage extent. Next, we assess the levels of lncRNA CRNDE, miR-29a-3p, TGF-β1, MCL-1, E-cadherin, vimentin, and snail. We counted the percentages of Th17 cells using flow cytometry. Finally, we performed a dual-luciferase reporter assay to assess the association between lncRNA CRNDE and miR-29a-3p.

Results

We successfully established asthma mouse/cell models and selected the lncRNA CRNDE for our study. Transfection of si-CRNDE reduced the degree of injury and inflammation in the mouse model and reversed the TGF-β1-induced epithelial-mesenchymal transition (EMT) in the cell model. Moreover, the E-cadherin level was upregulated, and the levels of IL-17A, vimentin, snail, and α-SMA were downregulated. We also discovered that lncRNA CRNDE negatively regulated miR-29a-3p and that this one in turn inhibited MCL-1 in mice. After lncRNA CRNDE expression downregulation, the level of miR-29a-3p was increased, and we detected reduced levels of MCL-1 and EMTs.

Conclusions

lncRNA CRNDE expression downregulation led to reduced inflammation and reduced lung damage in mice with induced asthma, it inhibited the EMTs of lung epithelial cells via the miR-29a-3p/MCL-1 pathway, and it reduced the levels of Th17/IL-17A cells to reduce asthma signs.

Collagen Triple Helix Repeat Containing 1 Deficiency Protects Against Airway Remodeling and Inflammation in Asthma Models In Vivo and In Vitro

Asthma is a chronic inflammatory disease characterized by airway remodeling and lung inflammation. Collagen triple helix repeat containing 1 (CTHRC1), a glycoprotein, is involved in multiple pathological processes, including inflammation and fibrosis. However, the function of CTHRC1 in asthma remains unclear. In the present study, the mouse asthma model was successfully generated by sensitizing and challenging mice with ovalbumin (OVA). CTHRC1 expression at both RNA and protein levels was significantly upregulated in lung tissues of asthmatic mice. Asthmatic mice exhibited significant airway remodeling as evidenced by increased bronchial wall and smooth muscle cell layer thickness, goblet cell hyperplasia and collagen deposition, and epithelial-mesenchymal transition (EMT), but those characteristics were reversed by CTHRC1 silencing. The cell model with transforming growth factor-β1 (TGF-β1) induction in bronchial epithelial cells (BEAS-2B) was conducted to verify the effects of CTHRC1 on EMT, a classic mechanism that mediates airway remodeling. The results showed that TGF-β1 stimulation increased CTHRC1 expression, and CTHRC1 knockdown inhibited TGF-β1-induced EMT. OVA-treated mice also showed increased inflammatory cell infiltration and the production of OVA-specific immunoglobulin E (IgE), interleukin (IL)-4, IL-5, and IL-13, which were decreased by CTHRC1 downregulation. The effects of CTHRC1 on OVA-induced airway inflammation were further determined by treating BEAS-2B cells with IL-13, in which CTHRC1 knockdown reduced the IL-13-induced secretion of pro-inflammatory factors, including IL-4 and IL-5. In conclusion, these results indicate that CTHRC1 silencing attenuates asthmatic airway remodeling and inflammation in vivo and in vitro, suggesting that CTHRC1 may be a potential target for asthma treatment.

Developmental switch from morphological replication to compensatory growth for salamander lung regeneration

Salamanders possess a pair of lungs for active air breathing, but the lung respiration is fully operational only during the late stage of development, particularly after metamorphosis. Larval salamanders mainly exchange air through the gills and skin, thus sparing the developing lungs. Salamanders can repair their lungs after injury, but a comparative analysis of regenerative responses between the lungs of young and adult animals is lacking. In this study, lung resections were performed in both larval and adult newts (Pleurodeles waltl). The cellular dynamics, tissue morphology and organ function during lung regeneration were examined and the Yap mutants were produced with CRISPR tools. We found that salamander switches the regenerative strategies from morphological replication through the blastema formation to compensatory growth via resident epithelial cells proliferation upon pulmonary resection injury as it transitions beyond metamorphosis. The larval animals achieve lung regeneration by forming a transient blastema-like structure and regrowing full-sized developing lungs, albeit unventilated. The adults repair injured lungs via massive proliferating epithelial cells and by expanding the existing alveolar epithelium without neo-alveolarization. Yap signalling promotes epithelial cell proliferation and prevents epithelial-to-mesenchymal transition to restore functional respiration. The salamanders have evolved distinct regenerative strategies for lung repair during different phases of life. Our results demonstrate a novel strategy for functional lung recovery by inducing epithelial cell proliferation to strengthen the remaining alveoli without rebuilding new alveoli.

Single-cell transcriptomic characterization reveals the landscape of airway remodeling and inflammation in a cynomolgus monkey model of asthma

Monkey disease models, which are comparable to humans in terms of genetic, anatomical, and physiological characteristics, are important for understanding disease mechanisms and evaluating the efficiency of biological treatments. Here, we established an A.suum-induced model of asthma in cynomolgus monkeys to profile airway inflammation and remodeling in the lungs by single-cell RNA sequencing (scRNA-seq). The asthma model results in airway hyperresponsiveness and remodeling, demonstrated by pulmonary function test and histological characterization. scRNA-seq reveals that the model elevates the numbers of stromal, epithelial and mesenchymal cells (MCs). Particularly, the model increases the numbers of endothelial cells (ECs), fibroblasts (Fibs) and smooth muscle cells (SMCs) in the lungs, with upregulated gene expression associated with cell functions enriched in cell migration and angiogenesis in ECs and Fibs, and VEGF-driven cell proliferation, apoptotic process and complement activation in SMCs. Interestingly, we discover a novel Fib subtype that mediates type I inflammation in the asthmatic lungs. Moreover, MCs in the asthmatic lungs are found to regulate airway remodeling and immunological responses, with elevated gene expression enriched in cell migration, proliferation, angiogenesis and innate immunological responses. Not only the numbers of epithelial cells in the asthmatic lungs change at the time of lung tissue collection, but also their gene expressions are significantly altered, with an enrichment in the biological processes of IL-17 signaling pathway and apoptosis in the majority of subtypes of epithelial cells. Moreover, the ubiquitin process and DNA repair are more prevalent in ciliated epithelial cells. Last, cell-to-cell interaction analysis reveals a complex network among stromal cells, MCs and macrophages that contribute to the development of asthma and airway remodeling. Our findings provide a critical resource for understanding the principle underlying airway remodeling and inflammation in a monkey model of asthma, as well as valuable hints for the future treatment of asthma, especially the airway remodeling-characterized refractory asthma.

RNA Sequencing of Idiopathic Subglottic Stenosis Tissues Uncovers Putative Profibrotic Mechanisms and Identifies a Prognostic Biomarker

Idiopathic subglottic stenosis (iSGS) is a localized airway disease that almost exclusively affects females. Understanding the molecular mechanisms involved may provide insights leading to therapeutic interventions. Next-generation sequencing was performed on tissue sections from patients with iSGS (n = 22), antineutrophil cytoplasmic antibody-associated vasculitis (AAV; n = 5), and matched controls (n = 9) to explore candidate genes and mechanisms of disease. Gene expression changes were validated, and selected markers were identified by immunofluorescence staining. Epithelial-mesenchymal transition (EMT) and leukocyte extravasation pathways were the biological mechanisms most relevant to iSGS pathogenesis. Alternatively activated macrophages (M2) were abundant in the subepithelium and perisubmucosal glands of the airway in iSGS and AAV. Increased expression of the mesenchymal marker S100A4 and decreased expression of the epithelial marker epithelial cell adhesion molecule (EPCAM) further supported a role for EMT, but to different extents, in iSGS and antineutrophil cytoplasmic antibody-associated subglottic stenosis. In patients with iSGS, high expression of prostate transmembrane protein, androgen induced 1 (PMEPA1), an EMT regulator, was associated with a shorter recurrence interval (25 versus 116 months: hazard ratio = 4.16; P = 0.041; 95% CI, 1.056-15.60). Thus, EMT is a key pathogenetic mechanism of subglottic stenosis in iSGS and AAV. M2 macrophages contribute to the pathogenesis of both diseases, suggesting a shared profibrotic mechanism, and PMEPA1 may be a biomarker for predicting disease recurrence in iSGS.

Mast Cell Proteases Promote Diverse Effects on the Plasminogen Activation System and Wound Healing in A549 Alveolar Epithelial Cells

Tissue damage, epithelial alterations, and intraepithelial presence of mast cells (MCs) are characteristics of asthma pathogenesis. Increased alveolar infiltration of MC populations has also been identified as a feature of asthma and other chronic respiratory diseases. The asthma associated receptor, urokinase plasminogen activator receptor (uPAR), has been shown to regulate bronchial epithelial repair responses. However, the impact of MC tryptase and chymase on functional properties and expression of uPAR in alveolar epithelial cells have not been fully investigated. Alveolar epithelial cell migration and wound healing were investigated using holographic live cell imaging of A549 cells in a wound scratch model post stimulation with tryptase or chymase. The expression of uPAR was investigated on the protein and gene level from cellular supernatants and in bronchoalveolar lavage fluid fractions from allergic asthmatics. We found that tryptase improved wound healing capacity, cellular migration and membrane bound uPAR expression. Chymase reduced gap closure capacity, cellular migration and membrane bound uPAR expression but increased soluble uPAR release. Our data suggest a dual regulatory response from the MC proteases in events related to uPAR expression and wound healing which could be important features in asthmatic disease.

Pulmonary Fibrosis and Hypereosinophilia in TLR9-/- Mice Infected by Cryptococcus gattii

Cryptococcus gattii is a worldwide-distributed basidiomycetous yeast that can infect immunocompetent hosts. However, little is known about the mechanisms involved in the disease. The innate immune response is essential to the control of infections by microorganisms. Toll-like receptor 9 (TLR9) is an innate immune receptor, classically described as a non-methylated DNA recognizer and associated with bacteria, protozoa and opportunistic mycosis infection models. Previously, our group showed that TLR9^-/- mice were more susceptible to C. gattii after 21 days of infection. However, some questions about the innate immunity involving TLR9 response against C. gattii remain unknown. In order to investigate the systemic cryptococcal infection, we evaluated C57BL/6 mice and C57BL/6 TLR9^-/- after intratracheal infection with 10⁴C. gattii yeasts for 21 days. Our data evidenced that TLR9^-/- was more susceptible to C. gattii. TLR9^-/- mice had hypereosinophilia in pulmonary mixed cellular infiltrate, severe bronchiolitis and vasculitis and type 2 alveolar cell hyperplasia. In addition, TLR9^-/- mice developed severe pulmonary fibrosis and areas with strongly birefringent fibers. Together, our results corroborate the hypothesis that TLR9 is important to support the Th1/Th17 response against C. gattii infection in the murine experimental model.

TIM-4 in macrophages contributes to nasal polyp formation through the TGF-β1–mediated epithelial to mesenchymal transition in nasal epithelial cells

Chronic rhinosinusitis with nasal polyps (CRSwNP) is caused by prolonged inflammation of the paranasal sinus mucosa. The epithelial to mesenchymal transition (EMT) is involved in the occurrence and development of CRSwNP. The T-cell immunoglobulin domain and the mucin domain 4 (TIM-4) is closely related to chronic inflammation, but its mechanism in CRSwNP is poorly understood. In our study, we found that TIM-4 was increased in the sinonasal mucosa of CRSwNP patients and, especially, in macrophages. TIM-4 was positively correlated with α-SMA but negatively correlated with E-cadherin in CRS. Moreover, we confirmed that TIM-4 was positively correlated with the clinical parameters of the Lund-Mackay and Lund-Kennedy scores. In the NP mouse model, administration of TIM-4 neutralizing antibody significantly reduced the polypoid lesions and inhibited the EMT process. TIM-4 activation by stimulating with tissue extracts of CRSwNP led to a significant increase of TGF-β1 expression in macrophages in vitro. Furthermore, coculture of macrophages and human nasal epithelial cells (hNECs) results suggested that the overexpression of TIM-4 in macrophages made a contribution to the EMT process in hNECs. Mechanistically, TIM-4 upregulated TGF-β1 expression in macrophages via the ROS/p38 MAPK/Egr-1 pathway. In conclusion, TIM-4 contributes to the EMT process and aggravates the development of CRSwNP by facilitating the production of TGF-β1 in macrophages. Inhibition of TIM-4 expression suppresses nasal polyp formation, which might provide a new therapeutic approach for CRSwNP.

Relaxin Affects Airway Remodeling Genes Expression through Various Signal Pathways Connected with Transcription Factors

Fibrosis is one of the parameters of lung tissue remodeling in asthma. Relaxin has emerged as a natural suppressor of fibrosis, showing efficacy in the prevention of a multiple models of fibrosis. Therefore, the aim of this study was to analyze the aptitudes of relaxin, in the context of its immunomodulatory properties, in the development of airway remodeling. WI-38 and HFL1 fibroblasts, as well as epithelial cells (NHBE), were incubated with relaxin. Additionally, remodeling conditions were induced with two serotypes of rhinovirus (HRV). The expression of the genes contributing to airway remodeling were determined. Moreover, NF-κB, c-Myc, and STAT3 were knocked down to analyze the pathways involved in airway remodeling. Relaxin decreased the mRNA expression of collagen I and TGF-β and increased the expression of MMP-9 (p < 0.05). Relaxin also decreased HRV-induced expression of collagen I and α-SMA (p < 0.05). Moreover, all the analyzed transcription factors—NF-κB, c-Myc, and STAT3—have shown its influence on the pathways connected with relaxin action. Though relaxin requires further study, our results suggest that this natural compound offers great potential for inhibition of the development, or even reversing, of factors related to airway remodeling. The presented contribution of the investigated transcription factors in this process additionally increases its potential possibilities through a variety of its activity pathways.

IL-33 biology in cancer: An update and future perspectives

Interleukin-33 (IL-33) is a member of the IL-1 family of cytokines that is constitutively expressed in the nucleus of epithelial, endothelial and fibroblast-like cells. Upon cell stress, damage or necrosis, IL-33 is released into the cytoplasm to exert its prime role as an alarmin by binding to its specific receptor moiety, ST2. IL-33 exhibits pleiotropic function in inflammatory diseases and particularly in cancer. IL-33 may play a dual role as both a pro-tumorigenic and anti-tumorigenic cytokine, dependent on tumor and cellular context, expression levels, bioactivity and the nature of the inflammatory environment. In this review, we discuss the differential contribution of IL-33 to malignant or inflammatory conditions, its multifaceted effects on the tumor microenvironment, while providing possible explanations for the discrepant findings described in the literature. Additionally, we examine the emerging and divergent functions of IL-33 in the nucleus, and aspects of IL-33 biology that are currently under-addressed.

The Controversial Role of IL-33 in Lung Cancer

Interleukin-33 (IL-33) belongs to the interleukin-1 (IL-1) family, and its structure is similar to IL-18. When cells are damaged or undergo necrosis, mature form of IL-33 is secreted as a cytokine, which can activate the immune system and provide danger signals. The IL-33/ST2 signaling pathway is composed of IL-33, suppression of tumorigenicity 2 (ST2), and IL-1 receptor accessory protein (IL-1RAcP). IL-33 has been reported to be strongly associated with lung cancer progression, and can exhibit opposite effects on lung cancer under different conditions. In this review, we have summarized the structure and basic functions of IL-33, its possible function in immune regulation, and its role in pulmonary fibrosis as well as in lung cancer. We have highlighted the dual regulation of IL-33 in lung cancer and proposed potential lung cancer treatment regimens, especially new immunotherapies, based on its mechanism of action.