Human Neutrophil Elastase Induces MUC5AC Overexpression in Chronic Rhinosinusitis Through miR-146a

Neutrophil-Derived Proteases in Lung Inflammation: Old Players and New Prospects

Neutrophil-derived proteases are critical to the pathology of many inflammatory lung diseases, both chronic and acute. These abundant enzymes play roles in key neutrophil functions, such as neutrophil extracellular trap formation and reactive oxygen species release. They may also be released, inducing tissue damage and loss of tissue function. Historically, the neutrophil serine proteases (NSPs) have been the main subject of neutrophil protease research. Despite highly promising cell-based and animal model work, clinical trials involving the inhibition of NSPs have shown mixed results in lung disease patients. As such, the cutting edge of neutrophil-derived protease research has shifted to proteases that have had little-to-no research in neutrophils to date. These include the cysteine and serine cathepsins, the metzincins and the calpains, among others. This review aims to outline the previous work carried out on NSPs, including the shortcomings of some of the inhibitor-orientated clinical trials. Our growing understanding of other proteases involved in neutrophil function and neutrophilic lung inflammation will then be discussed. Additionally, the potential of targeting these more obscure neutrophil proteases will be highlighted, as they may represent new targets for inhibitor-based treatments of neutrophil-mediated lung inflammation.

The interplay of inflammation and remodeling in the pathogenesis of chronic rhinosinusitis: current understanding and future directions

Chronic rhinosinusitis (CRS), a common clinical condition characterized by persistent mucosal inflammation and tissue remodeling, has a complex pathogenesis that is intricately linked to innate and adaptive immunity. A number of studies have demonstrated that a variety of immune cells and cytokines that play a vital role in mediating inflammation in CRS are also involved in remodeling of the nasal mucosa and the cells as well as different cytokines involved in remodeling in CRS are also able to exert some influence on inflammation, even though the exact relationship between inflammation and remodeling in CRS has not yet been fully elucidated. In this review, the potential role of immune cells and cytokines in regulating inflammation and remodeling of CRS mucosa has been described, starting with the immune cells and cytokines that act together in inflammation and remodeling. The goal is to aid researchers in understanding intimate connection between inflammation and remodeling of CRS and to offer novel ideas for future research.

Insights into the epigenetics of chronic rhinosinusitis with and without nasal polyps: a systematic review

Background

Epigenetics facilitates insights on the impact of host environment on the genesis of chronic rhinosinusitis (CRS) through modulations of host gene expression and activity. Epigenetic mechanisms such as DNA methylation cause reversible but heritable changes in gene expression over generations of progeny, without altering the DNA base-pair sequences. These studies offer a critical understanding of the environment-induced changes that result in host predisposition to disease and may help in developing novel biomarkers and therapeutics. The goal of this systematic review is to summarize the current evidence on epigenetics of CRS with a focus on chronic rhinosinusitis with nasal polyps (CRSwNP) and highlight gaps that merit further research.

Methods

A systematic review of the English language literature was performed to identify investigations related to epigenetic studies in subjects with CRS.

Results

The review identified 65 studies. These have focused on DNA methylation and non-coding RNAs, with only a few on histone deacetylation, alternative polyadenylation, and chromatin accessibility. Studies include those investigating in vivo and in vitro changes or both. Studies also include animal models of CRS. Almost all have been conducted in Asia. The genome-wide studies of DNA methylation found differences in global methylation between CRSwNP and controls, while others specifically found significant differences in methylation of the CpG sites of the thymic stromal lymphopoietin (TSLP), IL-8, and PLAT. In addition, DNA methyltransferase inhibitors and histone deacetylase inhibitors were studied as potential therapeutic agents. Majority of the studies investigating non-coding RNAs focused on micro-RNAs (miRNA) and found differences in global expression of miRNA levels. These studies also revealed some previously known as well as novel targets and pathways such as tumor necrosis factor alpha, TGF beta-1, IL-10, EGR2, aryl hydrocarbon receptor, PI3K/AKT pathway, mucin secretion, and vascular permeability. Overall, the studies have found a dysregulation in pathways/genes involving inflammation, immune regulation, tissue remodeling, structural proteins, mucin secretion, arachidonic acid metabolism, and transcription.

Conclusions

Epigenetic studies in CRS subjects suggest that there is likely a major impact of the environment. However, these are association studies and do not directly imply pathogenesis. Longitudinal studies in geographically and racially diverse population cohorts are necessary to quantify genetic vs. environmental risks for CRSwNP and CRS without nasal polyps and assess heritability risk, as well as develop novel biomarkers and therapeutic agents.

Effects of Pendrin Protein in Nasal Epithelial Cells on Mucin Production in the Context of Type 2 Inflammation

Background: Chronic rhinosinusitis (CRS) is a heterogeneous disease. The pathogenesis of chronic sinusitis is still unclear; however, the nasal cavity and paranasal sinuses are commonly affected by type 2 inflammation, which is caused by Th2 cytokines such as interleukin (IL)-5, IL-4, and IL-13. Previous studies have shown that pendrin promotes local infiltration of neutrophils through the production of human neutrophil elastase (HNE), which is essential for the secretion of mucin 5AC (MUC5AC) in chronic inflammatory diseases of the lower respiratory tract. This study investigated pendrin expression and its relationship to mucin in type 2 inflammation. Methods: A total of 40 patients (10 CRS patients with nasal polyps,10 CRS patients without nasal polyps, and 20 nasal septum deviation patients) were included in this study and were divided into the CRS group and the NC group. A normal nasal mucosa tissue culture model was established in vitro. IL-13 was used to stimulate primary cultures of human nasal epithelial cells (HNECs). Western blot (WB), enzyme-linked immunosorbent assay (ELISA), and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression of pendrin, MUC5AC, and MUC5B. After transfecting HNECs with siRNA pendrin or negative control (NC), EGF receptor (EGFR), HNE, MUC5AC, and MUC5B expression were analyzed using qRT-PCR, WB, or ELISA in terms of their relationships with pendrin. Pendrin expression in the tissue was also analyzed. Results: After IL-13 stimulation, pendrin, MUC5AC, and MUC5B expression levels were upregulated; the optimal concentration of IL-13 was 50 ng/mL. The expression levels of HNE, EGFR, MUC5AC, and MUC5B were downregulated after transfection with siRNA pendrin-1650. Pendrin expression in the NC group was lower than in the CRS group. Conclusion: IL-13 is implicated in the inflammation of nasal mucosa, and pendrin is closely related to the excessive secretion of mucin. The expression of mucin is downregulated after transfection with siRNA pendrin. There is a positive relationship between pendrin and EFGR/HNE. Moreover, pendrin plays an important role in type 2 inflammation.

Neutrophilic inflammation in chronic rhinosinusitis

PURPOSE OF REVIEW

Over the last years, extensive research has been done on neutrophils and their contribution in chronic rhinosinusitis (CRS), and made it clear that they are more than just a bystander in this disease. In this article, we will review all recent publications on this topic and look to what the future hold regarding therapeutics targeting the neutrophilic inflammation in CRS.

RECENT FINDINGS

Evidence is growing that the presence of neutrophils are associated with a worse disease outcome in certain CRS patient groups. They are highly activated in type 2 inflammations and exhibit damaging properties through their proteases, contributing to the chronicity of the disease. Several recent studies identified useful biomarkers and targets for future therapeutics.

SUMMARY

The findings we review in this manuscript are of utmost importance in unraveling the complexity of CRS and provide us with the necessary knowledge for future clinical practices.

Epigenetic modifications in chronic rhinosinusitis with and without nasal polyps

Chronic rhinosinusitis (CRS) has brought a huge socioeconomic burden. However, its mechanism is still elusive, which may involve genetic, environmental and some other factors. Epigenetic analyses have been conducted to explore the mechanisms underlying CRS. Here, we reviewed the fruits in the epigenetic studies on DNA methylation, histone modification, and non-coding RNA regulation. We concluded that the epigenetic research on CRS has made great breakthroughs, especially in the past 5 years and the field of microRNAs. "Epigenetic therapies" are expected to be designed to treat CRS in the future.

HNE Induces the Hyperexpression of MUC5AC in Chronic Rhinosinusitis With Nasal Polyps by Activating the TRAF6/Autophagy Regulatory Axis

BACKGROUND

Hypersecretion of mucin 5AC (MUC5AC) is a prominent feature of chronic rhinosinusitis with nasal polyps (CRSwNP) and autophagy plays a pivotal role in this process. TNF receptor-associated factor 6 (TRAF6) functions as a signal transducer in many inflammation diseases, whereas the correlation between TRAF6 and autophagy in CRSwNP remains unclear.

OBJECTIVE

To investigate the role of TRAF6 in the human neutrophil elastase (HNE)-induced autophagy and mucin MUC5AC over-expression in CRSwNP.

METHODS

Tissue specimens were obtained from control subjects and patients with CRSwNP. The relationships between HNE, TRAF6, autophagy, and MUC5AC were investigated. The effect of TRAF6 on HNE-mediated autophagy and hypersecretion of MUC5AC was assessed by in-vitro culture of HNECs treated with human recombinant HNE.

RESULTS

Patients with CRSwNP had more protein expression of HNE, MUC5AC, TRAF6, and light chain (LC3B), and increased levels of Beclin-1(BECN1) and autophagy-related gene 5 (ATG5) in mRNA level. Treatment of nasal epithelial cells with recombinant HNE induced the upregulation of TRAF6, autophagy, and MUC5AC. Alternatively, si-TRAF6 or autophagy inhibitor treatment mitigates the hyperexpression of MUC5AC before incubating with recombinant HNE.

CONCLUSION

HNE promotes autophagy through TRAF6, resulting in hyperexpression of MUC5AC in CRSwNP.

Current Insights on the Impact of Proteomics in Respiratory Allergies

Respiratory allergies affect humans worldwide, causing extensive morbidity and mortality. They include allergic rhinitis (AR), asthma, pollen food allergy syndrome (PFAS), aspirin-exacerbated respiratory disease (AERD), and nasal polyps (NPs). The study of respiratory allergic diseases requires new technologies for early and accurate diagnosis and treatment. Omics technologies provide the tools required to investigate DNA, RNA, proteins, and other molecular determinants. These technologies include genomics, transcriptomics, proteomics, and metabolomics. However, proteomics is one of the main approaches to studying allergic disorders' pathophysiology. Proteins are used to indicate normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. In this field, the principal goal of proteomics has been to discover new proteins and use them in precision medicine. Multiple technologies have been applied to proteomics, but that most used for identifying, quantifying, and profiling proteins is mass spectrometry (MS). Over the last few years, proteomics has enabled the establishment of several proteins for diagnosing and treating respiratory allergic diseases.

miR-1287-5p upregulation inhibits the EMT and pro-inflammatory cytokines in LPS-induced human nasal epithelial cells (HNECs)

BACKGROUND

Chronic rhinosinusitis is an intractable symptom that influences daily lives of patients. miR-1287-5p was discovered to play a suppressive role in cervical cancer and HBV-related infection.

PURPOSE

This study investigated the potential role of miR-1287-5p in the in-vitro model of chronic rhinosinusitis.

METHODS

GSE169376 dataset was analyzed and differential miRNAs in nasal mucosa tissues in the chronic rhinosinusitis group were screened out. LPS was used to treat HNECs for 12h, 24h and 48h. Cells underwent LPS treatment after SNAI1 downregulation, miR-1287-5p upregulation or pretreatment of the HMGB1 inhibitor, Glycyrrhizin. RT-PCR was used to measure the RNA expression of miR-1287-5p, SNAI1 and HMGB1. ELISA was used for the detection of IL-6, IL-8, TNF-α changes. Targetscan and starBase were used to predict the targets (SNAI1 and HMGB1) of miR-1287-5p. Dual-luciferase reporter assays were applied to validate this. Western blot was used to analyze the protein changes of Snai1, Vimentin, E-cadherin and HMGB1.

RESULTS

miR-1287-5p was downregulated in the chronic rhinosinusitis group and decreased after LPS treatment in HNECs. The upregulation of miR-1287-5p inhibited IL-6, IL-8, TNF-α and EMT. miR-1287-5p targeted and inhibited SNAI1 and HMGB1. SNAI1 downregulation led to inhibition in EMT while loss of HMGB1 contributed to the decrease in pro-inflammatory cytokines. Knockdown of SNAI1 decreased HMGB1, resulting in the reduction of pro-inflammatory cytokines while HMGB1 inhibitor reduced SNAI1 and thus suppressed the EMT process.

CONCLUSION

miR-1287-5p downregulation was associated with chronic rhinosinusitis and its upregulation inhibited the EMT and inflammation in LPS-induced HNECs through Snai1/HMGB1 pathway.

Higenamine alleviates allergic rhinitis by activating AKT1 and suppressing the EGFR/JAK2/c-JUN signaling

BACKGROUND

Allergic rhinitis (AR) is an inflammatory, immunoglobulin E (IgE)-mediated disease characterized by the typical symptoms of sneezing, rhinorrhea, nasal itching, and congestion. Higenamine (HG) is a plant-based alkaloid, possesses a wide range of activities, including vascular and tracheal relaxation, antioxidative, antiapoptotic, anti-inflammatory, and immunomodulatory activities. So far, the effect and the underlying mechanism of HG on AR have not been studied.

HYPOTHESIS/PURPOSE

The purpose of this study was to evaluate the effects of HG on AR and investigate its underlying mechanism.

METHODS

The effects of HG on AR were evaluated in an ovalbumin-induced AR mouse model. Network pharmacology-based methods such as target prediction, protein-protein interaction (PPI) network analysis, pathway analysis, and molecular docking were used to identify the likely HG targets. Finally, we validated the mechanism of action of HG through its effects on these targets in human nasal epithelial cells (HNEpCs).

RESULTS

Oral administration of 30, 60, and 120 mg/kg HG significantly alleviated rubbing and sneezing in AR mice and attenuated histopathological changes in the lung and nasal tissues. Additionally, HG reduced the levels of IgE, histamine, and IL-4 in the serum of AR mice, and regulated imbalance in Th1/Th2 cells. Using network pharmacology-based methods, we identified 29 HG targets related to AR. These targets are mainly involved in the PD-L1, relaxin, estrogen, HIF-1, Th1 and Th2 cell differentiation, T cell receptor, and the Th17 cell differentiation signaling pathways. Molecular docking showed that HG may well be suited to the receptor binding pockets of key target AKT1, EGFR, c-Jun, NOS2, and JAK2. In HNEpCs, HG inhibited the histamine-induced mRNA expression and secretion of interleukin (IL)-6, and IL-8, as well as the expression of MUC5AC and the phosphorylation of NF-κB. Moreover, HG affected the changes of AKT1, EGFR, c-Jun, iNOS, and JAK2 induced by histamine.

CONCLUSION

Overall, our results suggest that HG may alleviate AR by activating AKT1 and suppressing the EGFR/JAK2/c-JUN signaling. HG, therefore, has great potential as a therapeutic agent for the treatment of AR.

Gene Expression Profiles of Circular RNAs and MicroRNAs in Chronic Rhinosinusitis With Nasal Polyps

Introduction: Chronic rhinosinusitis (CRS) is often classified primarily on the basis of the absence or presence of nasal polyps (NPs), that is, as CRS with nasal polyps (CRSwNP) or CRS without nasal polyps (CRSsNP). Additionally, according to the percentage of eosinophils, CRSwNP can be further divided into eosinophilic CRSwNP (ECRSwNP) and non-ECRSwNP. CRSwNP is a significant public health problem with a considerable socioeconomic burden. Previous research reported that the pathophysiology of CRSwNP is a complex, multifactorial disease. There have been many studies on its etiology, but its pathogenesis remains unclear. Dysregulated expression of microRNAs (miRNAs) has been shown in psoriasis, rheumatoid arthritis, pulmonary fibrosis, and allergic asthma. Circular RNAs (circRNAs) are also involved in inflammatory diseases such as rheumatoid arthritis, septic acute kidney injury, myocardial ischemia/reperfusion injury, and sepsis-induced liver damage. The function of miRNAs in various diseases, including CRSwNP, is a research hotspot. In contrast, there have been no studies on circRNAs in CRSwNP. Overall, little is known about the functions of circRNAs and miRNAs in CRSwNP. This study aimed to investigate the expression of circRNAs and miRNAs in a CRSwNP group and a control group to determine whether these molecules are related to the occurrence and development of CRSwNP.

Methods: Nine nasal mucosa samples were collected, namely, three ECRSwNP samples, three non-ECRSwNP samples, and three control samples, for genomic microarray analysis of circRNA and microRNA expression. All of the tissue samples were from patients who were undergoing functional endoscopic sinus surgery in our department. Then we selected some differentially expressed miRNAs and circRNAs for qPCR verification. Meanwhile, GO enrichment analysis and KEGG pathway analysis were applied to predict the biological functions of aberrantly expressed circRNAs and miRNAs based on the GO and KEGG databases. Receiver operating characteristic (ROC) curve analysis and principal component analysis (PCA) were performed to confirm these molecules are involved in the occurrence and development of CRSwNP.

Results: In total, 2,875 circRNAs showed significant differential expression in the CRSwNP group. Specifically, 1794 circRNAs were downregulated and 1,081 circRNAs were upregulated. In the CRSwNP group, the expression of 192 miRNAs was significantly downregulated, and none of the miRNAs were significantly upregulated. GO and KEGG analysis showed differential circRNAs and miRNAs were enriched in “amoebiasis,” “salivary secretion,” “pathways in cancer,” and “endocytosis.” Through qRT-PCR verification, the expression profiles of hsa-circ-0031593, hsa-circ-0031594, hsa-miR-132-3p, hsa-miR-145-5p, hsa-miR-146a-5p, and hsa-miR-27b-3p were shown to have statistical differences. In addition, ROC curve analysis showed that the molecules with the two highest AUCs were hsa-circ-0031593 with AUC 0.8353 and hsa-miR-145-5p with AUC 0.8690. Through PCA with the six ncRNAs, the first principal component explained variance ratio was 98.87%. The AUC of the six ncRNAs was 0.8657.

Conclusion: In our study, the expression profiles of ECRSwNP and non-ECRSwNP had no statistical differences. The differentially expressed circRNAs and miRNAs between CRSwNP and control may play important roles in the pathogenesis of CRSwNP. Altered expression of hsa-circ-0031593 and hsa-miR-145-5p have the strongest evidence for involvement in the occurrence and development of CRSwNP because their AUCs are higher than the other molecules tested in this study.

Advances in the Knowledge of the Underlying Airway Remodeling Mechanisms in Chronic Rhinosinusitis Based on the Endotypes: A Review

Chronic rhinosinusitis (CRS) is a chronic inflammatory condition of the nasal and paranasal sinus mucosa that affects up to 10% of the population worldwide. CRS is the most representative disease of the upper respiratory tract where airway remodeling occurs, including epithelial damage, thickening of the basement membrane, fibrosis, goblet cell hyperplasia, subepithelial edema, and osteitis. CRS is divided into two phenotypes according to the presence or absence of nasal polyps: CRS with nasal polyp (CRSwNP) and CRS without nasal polyps (CRSsNP). Based on the underlying pathophysiologic mechanism, CRS is also classified as eosinophilic CRS and non-eosinophilic CRS, owing to Type 2 T helper (Th2)-based inflammation and Type 1 T helper (Th1)/Type 17 T helper (Th17) skewed immune response, respectively. Differences in tissue remodeling in CRS are suggested to be based on the clinical phenotype and endotypes; this is because fibrosis is prominent in CRSsNP, whereas edematous changes occur in CRSwNP, especially in the eosinophilic type. This review aims to summarize the latest information on the different mechanisms of airway remodeling in CRS according to distinct endotypes.

miR-30a-5p Inhibits Epithelial-to-Mesenchymal Transition by Targeting CDK6 in Nasal Polyps

BACKGROUND

Epithelial-to-Mesenchymal Transition (EMT) is considered as a crucial event in disease development and dysregulation of microRNAs (miRNAs) is involved in the regulation of EMT in various human diseases. Emerging evidences congregated over the years have demonstrated that miR-30a-5p was decreased in diseases and its overexpression inhibited the process of diseases via attenuating EMT. Although aberrant expression of miRNAs and occurrence of EMT were previously reported in Nasal Polyps (NPs), the role of miR-30a-5p in EMT of NPs is still remains unclear.

OBJECTIVE

The purpose of our present study was to explore the expression and potential function of miR-30a-5p in EMT of NPs.

METHODS

The expression of miR-30a-5p and mRNA expression level were detected by quantitative real-time PCR (qRT-PCR) in transforming growth factor β1 (TGF-β1) - induced EMT model and NPs patients. Western Blot (WB) and immunohistochemistry (IHC) were performed to evaluate the protein expression level of EMT markers. The cells mobility was assessed by Wound-Healing assay. Luciferase reporter assay was utilized to verify the relationship between Cyclin-dependent kinase 6 (CDK6) and miR-30a-5p.

RESULTS

Firstly, we observed that miR-30a-5p was down-regulated notably, accompanying with the alteration of EMT markers expression in NPs tissues and EMT model induced by TGF-β1 in primary Human Nasal Epithelial Cells (pHNECs) and A549 cells in vitro. Moreover, the functional assays demonstrated that overexpression of miR-30a-5p significantly inhibited EMT and cells mobility. Subsequently, CDK6 was validated as a direct target of miR-30a-5p. Finally, we performed the rescue experiments indicating that overexpression of CDK6 eliminated the suppressive effects of miR-30a-5p in TGF-β1-induced EMT in pHNECs and A549 cells.

CONCLUSION

Taken together, our results suggested that EMT was involved in NPs, and overexpression of miR-30a-5p could attenuate EMT via repressing the expression of the CDK6 in pHNECs and A549 cells.

Protease-Activated Receptor-2 Decreased Zonula Occlidens-1 and Claudin-1 Expression and Induced Epithelial Barrier Dysfunction in Allergic Rhinitis

BACKGROUND

Protease-activated receptor-2 (PAR-2)-modulated tight junctions (TJs) have been suggested to be involved in the pathogenesis of chronic inflammatory diseases. However, immunopathogenesis remains to be investigated among patients with allergic rhinitis (AR).

OBJECTIVE

This study sought to investigate the role of PAR-2 in the modulation of epithelial barrier function and the expression of TJs in the nasal mucosa of AR patients.

METHODS

The expression of TJs and PAR-2 of the nasal mucosa in AR patients and control subjects by immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR), and western blotting. In vitro, Primary human nasal epithelial cells (pHNECs) of AR patients were stimulated by Der p1 to analyze the correlation between PAR-2 and TJs expression. Der p1-induced pHNECs were treated with the PAR-2 agonist SLIGRL-NH2 and antagonist FSLLRY-NH2. Fluorescein isothiocyanate-dextran 4 kDa detection was employed as an indicator of epithelial permeability.

RESULTS

Lower expression levels of TJs in the nasal epithelium of AR patients were observed in comparison with that in control subjects. The PAR-2 level was markedly increased following treatment with 1,000 ng/mL of Der p1 for 24 hours in a cellular model of AR. The expression of PAR-2 was increased in Der p1-induced pHNECs of AR patients and correlated inversely with zonula occlidens (ZO)-1 and claudin-1. Treatment with Der p1 further downregulated TJs expression and promoted an increased epithelial permeability in Der p1-induced pHNECs.

CONCLUSIONS

PAR-2 could downregulate the expression of ZO-1 and claudin-1, which is involved in epithelial barrier dysfunction in AR.