IL-19 Up-Regulates Mucin 5AC Production in Patients With Chronic Rhinosinusitis via STAT3 Pathway

The signature based on interleukin family and receptors identified IL19 and IL20RA in promoting nephroblastoma progression through STAT3 pathway

Wilms tumor (WT) is a common renal malignancy in pediatric patients. Interleukin (receptors) (IL(R)s) play significant roles in tumor biology, however, their specific involvement in WT remains inadequately understood. We employed univariate Cox regression analysis to screen for certain IL(R) genes associated with prognosis and then analyzed their expression patterns. A prognostic model was constructed based on five selected IL(R)s using the LASSO Cox regression algorithm. To further elucidate the relationship between the prognostic model and the immune microenvironment, we conducted immune-related analyses. Additionally, we performed experiments to verify the roles of IL20RA and IL19 in WT. Finally, CNV, methylation and pan-cancer analysis were performed for IL19 and IL20RA. Our analysis ultimately identified five genes associated with prognosis: IL20RA, IL19, IL24, IL11 and IL17RD. The prognostic model incorporating these five genes demonstrated robust predictive power in both training and validation cohorts. Notably, IL19 and IL20RA were found to promote epithelial-mesenchymal transition (EMT) through the STAT3/SNAIL pathway, thereby contributing to tumor progression. Furthermore, significant differences in immune function and checkpoint expression were observed between the two groups. The high-risk group exhibiting a lower TIDE score, which suggests a potentially better response to immunotherapy. This study introduces a novel IL(R)-based prognostic signature for WT, highlighting IL20RA as a potential therapeutic target. These findings offer valuable insights for future studies on WT.

Interleukin-19 enhances eosinophil infiltration through upregulation of epithelium-derived RANTES expression via the ERK/NF-κB signalling pathway in patients with eosinophilic CRSwNP

BACKGROUD

The recurrence rate of chronic rhinosinusitis with nasal polyps (CRSwNP) is positively correlated with eosinophil infiltration. Increased interleukin (IL)-19 and eosinophil chemokine RANTES levels have been reported in patients with CRSwNP. This study aimed to clarify the role of IL-19 in mediating RANTES expression and eosinophilic infiltration in eosinophilic CRSwNP (Eos CRSwNP).

METHODS

Nasal tissue samples were obtained from patients with CRSwNP and controls. The expression of IL-19, its receptors, ECP, and RANTES in tissues was investigated. Primary human nasal epithelial cells (HNECs) and nasal polyp tissue blocks were cultured, then stimulated by IL-19; ERK phosphorylation, NF-κB pathway activation, RANTES level, eosinophils migration and infiltration were detected using RT-qPCR, ELISA, western blotting, HE, immunohistochemistry, immunofluorescence staining, confocal microscopy, and transwell migration assay.

RESULTS

The expression of IL-19 and its receptors (IL-20R1/IL-20R2), eosinophil cationic protein, and RANTES in nasal tissues from patients with Eos CRSwNP was significantly increased compared to that in non-Eos CRSwNP and control subjects. IL-19 co-localized with RANTES in nasal tissues and significantly elevated RANTES expression in HNECs. IL-19-blocking antibody and siRNA knockdown of IL-20R1 ameliorated the effect of IL-19 on RANTES secretion in HNECs. Moreover, IL-19-induced RANTES upregulation was associated with the activation of the ERK and NF-κB pathways. NF-κB activation was mediated by the ERK pathway in IL-19-treated HNECs, and IL-19 enhanced eosinophil infiltration in nasal polyp tissue blocks.

CONCLUSIONS

Our findings indicate that IL-19 promotes RANTES expression via the ERK/NF-κB pathway in HNECs and is implicated in eosinophil infiltration in patients with Eos CRSwNP.

IL-21 induces pyroptosis of Treg cells via Akt-mTOR-NLRP3-caspase 1 axis in eosinophilic chronic rhinosinusitis

BACKGROUND

Regulatory T (Treg) cells, which prevent inflammation-induced eosinophil infiltration, are deficient in nasal polyps (NPs) in patients with eosinophilic chronic rhinosinusitis (ECRS). It is concomitant with loss of Foxp3 after certain inflammatory stimuli.

OBJECTIVE

We sought to determine the inflammatory cytokines involved in inducing the loss of Treg cells in NPs.

METHODS

The abundance of cytokines in ECRS patients or mice were tested using ELISA, immunochemistry, immunofluorescence, quantitative reverse transcription PCR (qPCR), and/or flow cytometry. Expression of eosinophil cationic protein (ECP), CD4+ T cells, IL-4, and IL-17A and eosinophils in nasal mucosa of mouse model was investigated by immunochemistry, immunofluorescence, and hematoxylin and eosin staining. The percentage and death of induced Treg (iTreg) cells, source of IL-21 in NPs from ECRS and non-ECRS patients, and abundance of different systemic phenotypes of CD4+ T cells in a mouse model were studied by flow cytometry. Western blot analysis, scanning, and transmission electronic microscopy were used to detect pyroptosis of iTreg cells.

RESULTS

IL-21 was highly expressed in nasal mucosa of ECRS patients and mice, causing pyroptosis and preventing development of iTreg cells in vitro. The elevated IL-21 in NPs from ECRS patients was mainly produced by CD3+ T cells, including T follicular helper, T peripheral helper, TH2, and TH17 cells and CD3+CD4- T cells. T peripheral helper cells and CD3+CD4- T cells were the predominant source of IL-21 in NPs from non-ECRS patients. Blocking IL-21/IL-21R signaling significantly reduced the number of eosinophils and CD4+ T cells along with ECP, IL-4, and IL-17A expression in the nasal mucosa of ECRS mice. It also increased Treg cell percentage and systemically decreased TH2 and TH17 ratios. Akt-mTOR inhibition prevented IL-21-induced pyroptosis in human and mouse iTreg cells.

CONCLUSION

Elevated IL-21 drives pyroptosis and prevents Treg cell development in ECRS patients. IL-21 induced pyroptosis via activating Akt-mTOR-NLRP3-caspase 1 signaling.

Interleukin-19 upregulates fibronectin and collagen I expression via the NF-κB-Smad2/3 pathway in fibroblasts of patients with chronic rhinosinusitis

BACKGROUND

Tissue remodeling is a prominent characteristic of chronic rhinosinusitis (CRS). Excess deposition of fibronectin (FN) and collagen (Col) I by fibroblasts is crucial for the pathologic tissue remodeling in CRS without nasal polyps (CRSsNP). Increased interleukin (IL)-19 level in patients with CRS had been demonstrated in our previous studies. Here, we aimed to evaluate the role of IL-19 in mediating FN and Col I expression in CRS.

METHODS

Nasal mucosal tissue samples were collected from patients with CRS with nasal polyps (CRSwNP), CRSsNP, and controls. The expression of IL-19, vimentin, FN, and Col I were detected using immunohistochemistry and immunofluorescence. Primary human nasal fibroblasts were treated with IL-19, then the activation of Smad2/3, NF-κB and relevant pathways, and the expression of FN and Col I were measured.

RESULTS

Expression levels of vimentin, FN, and Col I were significantly increased in nasal tissues from patients with CRSsNP compared with CRSwNP and control subjects. Moreover, IL-19 co-localized with FN and Col Ι in nasal tissues. IL-19-treated fibroblasts had increased production of FN and Col I, which was associated with the activated Smad2/3 and NF-κB pathways. Moreover, Smad2/3 activation was mediated by the NF-κB pathway in IL-19-treated fibroblasts.

CONCLUSIONS

IL-19 promotes FN and Col I production via the activated NF-κB-Smad2/3 pathway in fibroblasts, leading to fibrosis and collagen deposition in patients with CRS.

A pilot prospective prevalence study of chronic rhinosinusitis associated with inflammatory bowel disease

Background

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract. Extra-intestinal manifestations such as pulmonary diseases have been reported. Chronic rhinosinusitis (CRS), an inflammatory condition of the sinonasal mucosa, has been associated with several lung diseases. Given the relationship between lung and intestinal pathologies, and lung and sinus pathologies, we aimed to determine the prevalence of IBD among CRS patients.

Methods

Pilot prevalence study. Ninety-two CRS patients were screened for IBD symptoms from October 2018 to January 2020. Patient-reported disease symptoms and overall quality of life were evaluated using the Sino-Nasal Outcome Test 22 (SNOT-22), Short Inflammatory Bowel Disease Questionnaire (SIBDQ), and EuroQol 5 Dimension 5 Level (EQ-5D-5L) questionnaires. The Modified Lund-Kennedy (MLK) endoscopic and Lund-Mackay (LM) grading systems were used to confirm CRS diagnoses. Individuals who reported subjective symptoms of IBD were referred to a gastroenterologist clinic for further diagnostics.

Results

Twenty of the 92 (20.2%, 95% CI: 12.6%-29.8%) CRS patients reported symptoms of IBD and four individuals (4.26%, 95% CI: 1.17%-10.50%) were subsequently diagnosed with IBD. Compared to patients without IBD symptoms (n = 72), those with symptoms (n = 20) reported significantly worse SNOT-22 (P = 0.002), SIBDQ (P < 0.05), and EQ-5D-3L (P = 0.0063) scores. However, these patients did not exhibit significantly different MLK (P = 0.81) or LM (P = 0.04) scores.

Conclusion

The prevalence of IBD may be elevated among individuals with CRS relative to the general Canadian population. This pilot study suggests that CRS with IBD is associated with lower quality of life. Further cross-sectional studies with larger sample sizes are required.

Roles of Exosomes in Chronic Rhinosinusitis: A Systematic Review

The pathophysiology of chronic rhinosinusitis (CRS) is multifactorial and not entirely clear. The objective of the review was to examine the current state of knowledge concerning the role of exosomes in CRS. For this systematic review, we searched PubMed/MEDLINE, Scopus, CENTRAL, and Web of Science databases for studies published until 7 August 2022. Only original research articles describing studies published in English were included. Reviews, book chapters, case studies, conference papers, and opinions were excluded. The quality of the evidence was assessed with the modified Office and Health Assessment and Translation (OHAT) Risk of Bias Rating Tool for Human and Animal Studies. Of 250 records identified, 17 were eligible, all of which had a low to moderate risk of overall bias. Presented findings indicate that exosomal biomarkers, including proteins and microRNA, act as promising biomarkers in the diagnostics and prognosis of CRS patients and, in addition, may contribute to finding novel therapeutic targets. Exosomes reflecting tissue proteomes are excellent, highly available material for studying proteomic alterations noninvasively. The first steps have already been taken, but more advanced research on nasal exosomes is needed, which might open a wider door for individualized medicine in CRS.

Expression of Major Lipid Raft Protein Raftlin in Chronic Rhinosinusitis with Nasal Polyps in Smoking and Non-Smoking Patients Correlated with Interleukin-17 and Tumor Necrosis Factor-α Levels

Raftlin, as an inflammatory biomarker, has been previously reported in chronic inflammatory diseases. This study investigates the expression of Raftlin in cigarette smokers and in chronic rhinosinusitis with nasal polyps (CRSwNP), as well as evaluating its correlation with interleukin-17 (IL-17) and tumor necrosis factor-α (TNF-α) levels. A total of 30 CRSwNP non-smoking and 16 CRSwNP + SK (smoking) patients undergoing endoscopic sinus surgery were enrolled, while 20 middle turbinate tissue pieces were examined and performed as the control group. In nasal mucosa epithelial staining, Raftlin levels were elevated in the columnar cells and were stained much more intensely in the CRSwNP and CRSwNP + SK groups. Raftlin was located more closely to the apical region of the epithelium in the CRSwNP + SK group; however, the Raftlin levels from whole nasal tissue pieces, according to ELISA data, showed that there was no significant difference between the three different study groups. A positive relationship by Pearson correlation was found between IL-17 or TNF-α levels and Raftlin levels. Taken together, these data indicate that increasing Raftlin expression in columnar cells might involve nasal epithelial remodeling in smokers with CRSwNP.

IL-10 family cytokines in chronic rhinosinusitis with nasal polyps: From experiments to the clinic

Chronic rhinosinusitis with nasal polyps (CRSwNP) is considered a nasal sinus inflammatory disease that can be dominated by immune cells and cytokines. IL-10 family cytokines exert essential functions in immune responses during infection and inflammation. Recently, the understanding of the roles of the IL-10 family in CRSwNP is being reconsidered. IL-10 family members are now considered complex cytokines that are capable of affecting epithelial function and involved in allergies and infections. Furthermore, the IL-10 family responds to glucocorticoid treatment, and there have been clinical trials of therapies manipulating these cytokines to remedy airway inflammatory diseases. Here, we summarize the recent progress in the understanding of IL-10 family cytokines in CRSwNP and suggest more specific strategies to exploit these cytokines for the effective treatment of CRSwNP.

XBP1 Regulates the Transcription of HIF-1a in BALB/c Mice with Chronic Rhinosinusitis without Polyps

X-box binding protein 1 (XBP1) is a transcription factor that recognizes the CRE-like element in enhancers of human T-cell leukemia virus and MHC class II gene and induces their transcription. This study was performed to characterize the function of XBP1, which was identified to be a differentially expressed gene via GEO database, in chronic rhinosinusitis (CRS) without nasal polyps (CRSsNP). XBP1 expression was significantly elevated in both CRSsNP patients and mice who were accompanied with mucosal thickening, goblet cell hyperplasia and chemosis, glandular hyperplasia, and dense infiltration of inflammatory cells. Silencing of XBP1 suppressed the development of CRSsNP in mice. Mechanistically, knockdown of XBP1 downregulated the expression of hypoxia-inducible factor 1-alpha (HIF-1a), and overexpression of XBP1 led to the opposite result. Silencing of HIF-1a inhibited β-catenin expression and impaired the Wnt/β-catenin pathway. Further overexpression of HIF-1a in XBP1-silenced CRSsNP mice exacerbated pathological changes in mouse nasal mucosal tissues, promoted inflammation, and activated the Wnt/β-catenin pathway. Taken together, overexpression of XBP1 may be associated with increased expression of HIF-1a and possibly contribute to the Wnt/β-catenin pathway activation and the development of CRSsNP.

Identification of IL20RB as a Novel Prognostic and Therapeutic Biomarker in Clear Cell Renal Cell Carcinoma

Background

Clear cell renal cell carcinoma (ccRCC) is a type of life-threatening malignant tumor of the urinary system. IL20RB, interleukin 20 receptor subunit beta, is a cytokine receptor subunit coding gene and was initially found to play a vital role in human cancers, while its role in ccRCC still remains unclear.

Methods

In this work, we explored the prognostic value and therapeutic potential of IL20RB in ccRCC mainly by online tools. Firstly, we used UALCAN and GEPIA to explore the expression profile and prognostic value of IL20RB in various cancers; the expression profile in tumor cell lines was also analysed with CCLE and Expression Atlas. Then, we decided to focus on ccRCC for further analysis; we further demonstrated the significant correlation between expression and clinical features by GEPIA and UALCAN. In order to reveal the potential intrinsic mechanism responsible for the upregulation of IL20RB in ccRCC, we made genetic alternation analysis and methylation analysis. cBioPortal was used for genetic alternation analysis. UALCAN, MethSurv, and Xena were used for methylation analysis. To learn details of how IL20RB might function in ccRCC, we further conducted functional analysis and immune infiltration analysis. STRING and GSEA were used to do functional analysis. TIMER was used for immune infiltration analysis; KM plotter was used for survival analysis.

Results

Results show that IL20RB is upregulated in ccRCC, and low methylation may be responsible for its upregulation. Both high expression and low methylation of IL20RB predict worse survival, and both have a strong positive correlation with clinical characteristics. In addition, results indicate that there exists a crosstalk between IL20RB and neutrophils. Furthermore, the immune microenvironment could influence the prognosis predicting ability of IL20RB.

Conclusions

In conclusion, IL20RB plays an important role in ccRCC and is identified as a novel prognostic and potential therapeutic biomarker in ccRCC.

Distinct Secretion of MUC5AC and MUC5B in Upper and Lower Chronic Airway Diseases

The human airway is protected by a defensive mucus barrier. The most prominent components of mucus are the mucin glycoproteins MUC5AC and MUC5B. They are produced by goblet cells and submucosal gland cells in the upper and lower airways. Hyperplasia of these cells and hypersecretion of MUC5AC and MUC5B characterize chronic inflammatory diseases of the upper and lower airways. Recent studies have revealed that MUC5AC and MUC5B are expressed at specific sites in the respiratory tract through different molecular mechanisms and have distinct functions. Morphometric and histochemical studies have also examined the roles of goblet cells, submucosal gland cells, MUC5AC, and MUC5B in different chronic airway diseases individually. The individual study of goblet cells, submucosal gland cells, MUC5AC, and MUC5B in airway diseases would be helpful for precisely diagnosing chronic inflammatory diseases of the airway and establishing optimal treatments. This review focuses on the distinct secretion of MUC5AC and MUC5B and their producing cells in chronic inflammatory diseases of the upper and lower airway.

JAK2 Phosphorylation Signals and Their Associated Cytokines Involved in Chronic Rhinosinusitis with Nasal Polyps and Correlated with Disease Severity

Janus kinase 2 (JAK2) is a member of the JAK family that transduces cytokine-mediated signals via the JAKs/STATs (signal transducer and activator of transcription proteins) pathway, which plays an important role in many inflammatory diseases. This study investigates the association of p-JAK2 and JAK2-associated cytokines from nasal polyp (NP) tissue with disease severity, and evaluates the p-JAK2-mediated STATs in chronic rhinosinusitis (CRS) with NP. Sixty-one CRSwNP patients with nasal polyps undergoing endoscopic sinus surgery were enrolled, while the turbinate tissues from 26 nasal obstruction patients were examined as the control group. Elevated levels of p-JAK2 were detected in CRSwNP, and significantly correlated with scores of disease severity (LMK-CT, TPS, and SNOT-22). Expressions of the JAK2-associated cytokines, such as IL-5, IL-6, IL-13, G-CSF, and IFN-γ were significantly higher in CRSwNP than in the controls, while the levels of IL-5, IL-6, IL-13, or G-CSF had positive correlation with scores of disease severity. Moreover, markedly increased expression of p-STAT3 in CRSwNP was observed relative to the control. Taken together, these data showed that the JAK2-associated cytokines including IL-6 and G-CSF may stimulate JAK2 phosphorylation to activate p-STAT3, indicating an association with disease severity and supporting its development of JAK2 inhibitor as a potential therapeutic agent for CRS.

Mucin 5AC is significantly upregulated in exosomes from the nasal lavage fluid and may promote the expression of COX-2, VEGF and MMP-9: an implication in nasal polyp pathogenesis

BACKGROUND

Exosomes are critical mediators of intercellular communication and could be involved in many human diseases; however, little is known about the role of exosomes in nasal polyps (NP).

METHODS

Exosomes in nasal lavage fluids (NLF) were isolated by ultracentrifugation. Exosome identity was validated by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and specific exosomal markers. The exosome proteome was revealed by LC-MS/MS, and the expression of the candidate exosomal protein, mucin 5AC, was confirmed by Western blot analysis and immunohistochemistry (IHC). Cellular uptake of the exosomes was monitored by fluorescence confocal microscopy and the ensuing effects on COX-2, VEGF and MMP-2/MMP-9 were determined by Western blotting, ELISA and gelatin zymography, respectively.

RESULTS

Mass spectrometry analysis and subsequent verification by Western blotting identified that mucin 5AC was significantly upregulated in exosomes from NLFs of NP patients. Moreover, the expression of mucin 5AC was increased in the tissue specimens of the NP patients. Functional assays suggest that the mucin 5 AC-enriched exosomes could be effectively taken up by chronic rhinosinusitis without NP (CRSsNP)-derived fibroblasts, the control cells, resulting in a significant increase in the expression of COX-2, VEGF and MMP-9.

CONCLUSIONS

Mucin 5AC, the major airway mucin, cannot only be carried and transferred by nasal exosomes, but may also promote tissue remodeling and angiogenesis and thus could be a potential therapeutic target of NP.

IL-19 induced by IL-13/IL-17A in the nasal epithelium of patients with chronic rhinosinusitis upregulates MMP-9 expression via ERK/NF-κB signaling pathway

Background

Tissue remodeling is a crucial characteristic of chronic rhinosinusitis (CRS). Imbalance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) is crucial for the pathologic tissue remodeling in CRS. Elevation of interleukin (IL)‐19 or MMP‐9 levels in patients with CRS had been proven in previous studies. Here, we aimed to investigate the role of IL‐19 in mediating MMP‐9 expression in CRS.

Methods

Nasal tissue samples were collected from 45 individuals having chronic rhinosinusitis with nasal polyps (CRSwNP), 24 CRS without nasal polyps (CRSsNP), and 17 controls. Expression of IL‐19, its receptors (IL‐20R1/IL‐20R2), and MMP‐9 were investigated using RT‐qPCR and Immunofluorescence (IF). Human nasal epithelial cells (HNECs) were stimulated by IL‐19; ERK phosphorylation, nuclear factor‐κB (NF‐κB) pathway activation, and MMP‐9 level were detected by RT‐qPCR, enzyme‐linked immunosorbent assay, western blot, and IF. We also explored the effect of type1/2/3 cytokines on IL‐19 production by RT‐qPCR, and western blot.

Results

Expression levels of IL‐19, its receptors (IL‐20R1/IL‐20R2), and MMP‐9 were increased in nasal tissues from individuals with CRSwNP compared to those with CRSsNP as well as the controls. IL‐19 significantly elevated the production of MMP‐9 in HNECs. Furthermore, IL‐19 could activate the ERK and NF‐κB pathways, accompanied by increased MMP‐9 production in HNECs. Conversely, both ERK and NF‐κB inhibitors significantly attenuated the role of IL‐19 in MMP‐9 production. siRNA knockdown of IL‐20R1 suppressed ERK and NF‐κB pathway activation, thereby decreasing MMP‐9 expression. IL‐13 and IL‐17A were found to stimulate IL‐19 production in HNECs.

Conclusion

IL‐19, promoted by IL‐13 and IL‐17A, contributes to the upregulation of secretion of the tissue remodeling factor MMP‐9 in patients with CRS.

Regulation of Skin Barrier Function via Competition between AHR Axis versus IL-13/IL-4‒JAK‒STAT6/STAT3 Axis: Pathogenic and Therapeutic Implications in Atopic Dermatitis

Atopic dermatitis (AD) is characterized by skin inflammation, barrier dysfunction, and chronic pruritus. As the anti-interleukin-4 (IL-4) receptor α antibody dupilumab improves all three cardinal features of AD, the type 2 cytokines IL-4 and especially IL-13 have been indicated to have pathogenic significance in AD. Accumulating evidence has shown that the skin barrier function is regulated via competition between the aryl hydrocarbon receptor (AHR) axis (up-regulation of barrier) and the IL-13/IL-4‒JAK‒STAT6/STAT3 axis (down-regulation of barrier). This latter axis also induces oxidative stress, which exacerbates inflammation. Conventional and recently developed agents for treating AD such as steroid, calcineurin inhibitors, cyclosporine, dupilumab, and JAK inhibitors inhibit the IL-13/IL-4‒JAK‒STAT6/STAT3 axis, while older remedies such as coal tar and glyteer are antioxidative AHR agonists. In this article, I summarize the pathogenic and therapeutic implications of the IL-13/IL-4‒JAK‒STAT6/STAT3 axis and the AHR axis in AD.

Proteomic analysis of nasal mucus samples of healthy patients and patients with chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) has a complex and multifactorial pathogenesis with a heterogeneous inflammatory profile. Proteomic analysis of nasal mucus may enable further understanding of protein abundances and biologic processes present in CRS and its endotypes compared with in healthy patients.

OBJECTIVE

Our aim was to determine differences in the nasal mucus proteome of healthy patients and patients with CRS.

METHODS

Nasal mucus was obtained from healthy patients, patients with CRS without nasal polyps (CRSsNP), and patients with CRS with nasal polyps (CRSwNP) before surgery. Gel electrophoresis was performed to fractionate the complex protein extracts before mass spectrometry analysis. Gene set enrichment analysis was performed on differentially expressed proteins.

RESULTS

A total of 33 patients were included in this study (12 healthy, 10 with CRSsNP, and 11 with CRSwNP). In all, 1142 proteins were identified in mucus samples from healthy patients, 761 in mucus samples from patients with CRSsNP, and 998 in mucus samples from patients with CRSwNP. Dysfunction in immunologic pathways, reduced cellular signaling, and increased cellular metabolism with associated tissue remodeling pathways were present in patients with CRS compared with in healthy patients.

CONCLUSION

Significant downregulation of mucosal immunity and antioxidant pathways with increased tissue modeling processes may account for the clinical manifestations of CRS. Ultimately, the differing proteome and biologic processes provide further insight into CRS pathogenesis and its endotypes.

Regulation of Filaggrin, Loricrin, and Involucrin by IL-4, IL-13, IL-17A, IL-22, AHR, and NRF2: Pathogenic Implications in Atopic Dermatitis

Atopic dermatitis (AD) is an eczematous, pruritic skin disorder with extensive barrier dysfunction and elevated interleukin (IL)-4 and IL-13 signatures. The barrier dysfunction correlates with the downregulation of barrier-related molecules such as filaggrin (FLG), loricrin (LOR), and involucrin (IVL). IL-4 and IL-13 potently inhibit the expression of these molecules by activating signal transducer and activator of transcription (STAT)6 and STAT3. In addition to IL-4 and IL-13, IL-22 and IL-17A are probably involved in the barrier dysfunction by inhibiting the expression of these barrier-related molecules. In contrast, natural or medicinal ligands for aryl hydrocarbon receptor (AHR) are potent upregulators of FLG, LOR, and IVL expression. As IL-4, IL-13, IL-22, and IL-17A are all capable of inducing oxidative stress, antioxidative AHR agonists such as coal tar, glyteer, and tapinarof exert particular therapeutic efficacy for AD. These antioxidative AHR ligands are known to activate an antioxidative transcription factor, nuclear factor E2-related factor 2 (NRF2). This article focuses on the mechanisms by which FLG, LOR, and IVL expression is regulated by IL-4, IL-13, IL-22, and IL-17A. The author also summarizes how AHR and NRF2 dual activators exert their beneficial effects in the treatment of AD.