Autophagy is deficient in nasal polyps: implications for the pathogenesis of the disease

Macrophages in CRSwNP: Do they deserve more attention?

Chronic rhinosinusitis (CRS) represents a heterogeneous disorder primarily characterized by the persistent inflammation of the nasal cavity and paranasal sinuses. The subtype known as chronic rhinosinusitis with nasal polyposis (CRSwNP) is distinguished by a significantly elevated recurrence rate and augmented challenges in the management of nasal polyps. The pathogenesis underlying this subtype remains incompletely understood. Macrophages play a crucial role in mediating the immune system's response to inflammatory stimuli. These cells exhibit remarkable plasticity and heterogeneity, differentiating into either the pro-inflammatory M1 phenotype or the anti-inflammatory and reparative M2 phenotype depending on the surrounding microenvironment. In CRSwNP, macrophages demonstrate reduced production of Interleukin 10 (IL-10), compromised phagocytic activity, and decreased autophagy. Dysregulation of pro-resolving mediators may occur during the inflammatory resolution process, which could potentially hinder the adequate functioning of anti-inflammatory macrophages in facilitating resolution. Collectively, these factors may contribute to the prolonged inflammation observed in CRSwNP. Additionally, macrophages may enhance fibrin cross-linking through the release of factor XIII-A (FAXIII), promoting fibrin deposition and plasma protein retention. Macrophages also modulate vascular permeability by releasing Vascular endothelial growth factor (VEGF). Moreover, they may disrupt the balance between Matrix Metalloproteinases (MMPs) and Tissue Inhibitors of Metalloproteinases (TIMPs), which favors extracellular matrix (ECM) degradation, edema formation, and pseudocyst development. Accumulating evidence suggests a close association between macrophage infiltration and CRSwNP; however, the precise mechanisms underlying this relationship warrant further investigation. In different subtypes of CRSwNP, different macrophage phenotypic aggregations trigger different types of inflammatory features. Increasing evidence suggests that macrophage infiltration is closely associated with CRSwNP, but the mechanism and the relationship between macrophage typing and CRSwNP endophenotyping remain to be further explored. This review discusses the role of different types of macrophages in the pathogenesis of different types of CRSwNP and their contribution to polyp formation, in the hope that a better understanding of the role of macrophages in specific CRSwNP will contribute to a precise and individualized understanding of the disease.

Autophagy in chronic rhinosinusitis with or without nasal polyps

Basic research on chronic rhinosinusitis (CRS) has advanced significantly in the past two decades, yet a comprehensive understanding of its pathogenic mechanisms remains elusive. Concurrently, there is a growing interest among scientists in exploring the involvement of autophagy in various human diseases, including tumors and inflammatory conditions. While the role of autophagy in asthma has been extensively studied in airway inflammatory diseases, its significance in CRS with or without nasal polyps (NPs), a condition closely linked to asthma pathophysiology, has also garnered attention, albeit with conflicting findings across studies. This review delves into the role of autophagy in CRS, suggesting that modulating autophagy to regulate inflammatory responses could potentially serve as a novel therapeutic target.

The role of autophagy regulated by the PI3K/AKT/mTOR pathway and innate lymphoid cells in eosinophilic chronic sinusitis with nasal polyps

BACKGROUND

The PI3K/Akt/mTOR pathway and autophagy are important physiological processes. But their roles in eCRSwNP remains controversial.

METHODS

In this study, we used the eCRSwNP mouse model, PI3K/Akt/mTOR pathway inhibitors, and autophagy inhibitors and activators to investigate the regulatory effects of the PI3K/Akt/mTOR pathway on autophagy, and their effects on eosinophilic inflammation, and tissue remodeling. The role of ILC2s in eCRSwNP was also studied, and the relationship between ILC2s and autophagy was preliminarily determined.

RESULTS

Our results show that eosinophilic inflammation in eCRSwNP mice could be inhibited by promoting the autophagy; otherwise, eosinophilic inflammation could be promoted. Meanwhile, inhibition of the PI3K/Akt/mTOR pathway can further promote autophagy and inhibit eosinophilic inflammation. Meanwhile, inhibiting the PI3K/Akt/mTOR pathway and promoting autophagy can reduce the number of ILC2s and the severity of tissue remodeling in the nasal polyps of eCRSwNP mice.

CONCLUSIONS

We conclude that the PI3K/Akt/mTOR pathway plays roles in eosinophilic inflammation and tissue remodeling of eCRSwNP, in part by regulating the level of autophagy. The downregulation of autophagy is a pathogenesis of eCRSwNP; therefore, the recovery of normal autophagy levels might be a new target for eCRSwNP therapy. Furthermore, autophagy might inhibit eosinophilic inflammation and tissue remodeling, in part by reducing the number of ILC2s.

Increased epithelial mTORC1 activity in chronic rhinosinusitis with nasal polyps

Background

The airway epithelium plays a central role in the pathogenesis of chronic respiratory diseases such as asthma and chronic rhinosinusitis with nasal polyps (CRSwNP), but the mechanisms by which airway epithelial cells (EpCs) maintain inflammation are poorly understood.

Objective

We hypothesized that transcriptomic assessment of sorted airway EpCs across the spectrum of differentiation would allow us to define mechanisms by which EpCs perpetuate airway inflammation.

Methods

Ethmoid sinus EpCs from adult patients with CRS were sorted into 3 subsets, bulk RNA sequenced, and analyzed for differentially expressed genes and pathways. Single cell RNA-seq (scRNA-seq) datasets from eosinophilic and non-eosinophilic CRSwNP and bulk RNA-seq of EpCs from mild/moderate and severe asthma were assessed. Immunofluorescent staining and ex vivo functional analysis of sinus EpCs were used to validate our findings.

Results

Analysis within and across purified EpC subsets revealed an enrichment in glycolytic programming in CRSwNP vs CRSsNP. Correlation analysis identified mammalian target of rapamycin complex 1 (mTORC1) as a potential regulator of the glycolytic program and identified EpC expression of cytokines and wound healing genes as potential sequelae. mTORC1 activity was upregulated in CRSwNP, and ex vivo inhibition demonstrated that mTOR is critical for EpC generation of CXCL8, IL-33, and CXCL2. Across patient samples, the degree of glycolytic activity was associated with T2 inflammation in CRSwNP, and with both T2 and non-T2 inflammation in severe asthma.

Conclusions

Together, these findings highlight a metabolic axis required to support epithelial generation of cytokines critical to both chronic T2 and non-T2 inflammation in CRSwNP and asthma.

The Roles of Autophagy, Mitophagy, and the Akt/mTOR Pathway in the Pathogenesis of Chronic Rhinosinusitis with Nasal Polyps

The pathogenesis of CRSwNP is complex and unclear. CRSwNP is subdivided into two types based on the infiltration of EOSs: eCRSwNP and noeCRSwNP. This study was designed to seek the role of autophagy, mitophagy, and Akt/mTOR pathway in these two subtypes of CRSwNP. This study included 29 patients with CRSwNP and 9 controls. The levels of autophagy, mitophagy, and Akt/mTOR pathway-related proteins in nasal tissues were quantified using western blot analysis. Levels of eosinophilic inflammation-related cytokines in nasal tissues were quantified by enzyme-linked immunosorbent assay. Immunohistochemistry was also used to evaluate autophagy, mitophagy, and Akt/mTOR pathway-related protein expression and distribution in nasal polyps and control tissues. Transmission electron microscopy was used to detect the formation of autophagosomes and mitochondrial autophagosomes. Masson's trichrome and periodic acid–Schiff Alcian blue staining were used to evaluate the severity of tissue remodeling. The expression of p-Akt/Akt and p-mTOR/mTOR was upregulated in patients with eCRSwNP or noeCRSwNP. Beclin 1, PINK1, BNIP3, and FUNDC1 levels were significantly reduced in the nasal polyps of patients with eCRSwNP or noeCRSwNP. Autophagosomes and mitochondrial autophagosomes formed less frequently in the nasal polyps of patients with eCRSwNP or noeCRSwNP. Levels of IL-4, IL-5, IL-13, and ECP and the eotaxins CCL11, CCL24, and CCL26 were elevated in the nasal polyps of patients with eCRSwNP or noeCRSwNP. Tissue remodeling is enhanced in patients with eCRSwNP or noeCRSwNP. The Akt/mTOR pathway, eosinophilic inflammation, and tissue remodeling are activated in the nasal polyps of patients with eCRSwNP or noeCRSwNP. The downregulation of autophagy and mitophagy is also observed in eosinophilic and noneosinophilic nasal polyps. The targeting of mitophagy may provide new therapeutic options for different endotypes of CRSwNP.

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.

Autophagy Is Deficient and May be Negatively Regulated by SERPINB3 in Middle Ear Cholesteatoma

HYPOTHESIS

Whereas autophagy has been linked to various human diseases, whether it also plays a role in cholesteatoma is virtually unknown. This study aimed to investigate the activity and regulation of autophagy in cholesteatoma.

BACKGROUND

The treatment of middle ear cholesteatoma has been challenging due to an insufficient understanding of the underlying disease mechanism.

METHODS

Expression of microtubule-associated protein 1A/1B-light chain 3 (LC3), the autophagy protein marker, and phosphorylated Akt (p-Akt), and mammalian target of rapamycin (p-mTOR), the known autophagy regulators, in fresh retroauricular skin and cholesteatoma tissue samples was analyzed by immunoblotting. The results were further confirmed by immunohistochemistry and statistical analyses. Cell proliferation of primary retroauricular skin- and cholesteatoma-derived fibroblasts was evaluated by methyl thiazol tetrazolium (MTT) assay. Ectopic expression of serine proteinase inhibitor, clade B, member 3 (SERPINB3) in the fibroblasts was achieved by electroporation and the expression was detected by immunoblotting.

RESULTS

LC3 expression was significantly decreased in cholesteatoma in most of the 15 paired retroauricular skin/cholesteatoma tissue samples. However, p-Akt and p-mTOR expression in the cholesteatoma samples was not significantly different from that in the control subjects. Immunohistochemical studies further demonstrated an inverse correlation between LC3 expression and cholesteatoma. The cholesteatoma fibroblasts proliferated faster than the retroauricular skin fibroblasts, and had higher SERPINB3 but lower LC3 expression. Furthermore, overexpression of SERPINB3 in the retroauricular skin fibroblasts enhanced cell proliferation and downregulated LC3 expression.

CONCLUSION

Autophagy is significantly suppressed in cholesteatoma tissues, which may not involve the Akt/mTOR signaling pathway. More importantly, SERPINB3 may promote cell proliferation and negatively regulate autophagy in cholesteatoma fibroblasts. Together, these findings warrant further investigation into the pathogenic mechanism of cholesteatoma.

Associations between TMEM196 polymorphisms and NSAID-exacerbated respiratory disease in asthma

BACKGROUND

We previously found differences in the minor allele frequency (MAF) of single-nucleotide polymorphisms (SNPs) in transmembrane protein 196 (TMEM196) between 995 patients with aspirin-tolerant asthma (ATA) and 141 asthmatic patients with NSAID-exacerbated respiratory disease (NERD). In this study, we statistically analyzed the distributions of the genotypes and haplotypes of these SNPs to determine the exact association between TMEM196 genetic variants and the risk for NERD.

MATERIALS AND METHODS

Lewontin's D' and r values were used to measure linkage disequilibrium between the biallelic loci having MAFs more than 0.05, and haplotypes were inferred using the PHASE algorithm (version 2.0). The genotype distribution was analyzed by logistic regression models using age of onset, smoking status (nonsmoker=0, ex-smoker=1, smoker=2), and BMI as covariates. Regression analysis of the association between SNPs and the risk of NERD was analyzed using SPSS version 12.0 and PLINK version 1.9.

RESULTS

The MAF of rs9886152 C>T was significantly lower in NERD than in ATA [24.8 vs. 34.0%, odds ratio=0.64 (0.48-0.85), P=2.07×10, Pcorr=0.048]. The rate of the rs9886152 C>T minor allele was significantly lower in NERD than in ATA [44.0 vs. 56.4% in the codominant model, P=0.002, Pcorr=0.049, odds ratio=0.64 (0.48-0.85)]. An additional three SNPs (rs9639334 A>G, rs9638765 A>G, and rs2097811 G>A) showed similar associations with the risk of NERD. NERD patients had lower frequencies of the rs9639334 A>G minor allele (51.1 vs. 64.4%, P=0.002, Pcorr=0.043), rs9638765 A>G (49.7 vs. 64.2%, P=0.001, Pcorr=0.017), and rs2097811 G>A (51.1 vs. 64.5%, P=0.002, Pcorr=0.04) compared with ATA patients. Patients homozygous for the minor alleles of the four SNPs showed significantly less of an aspirin-induced decrease in forced expiratory volume in one second compared with those homozygous for the common alleles (P=0.003-0.012).

CONCLUSION

The minor alleles of the four SNPs in TMEM196 may exert a protective effect against the development of NERD and may be useful genetic markers to predict the risk of NERD.

The circular RNA hsa-circ-0072309 plays anti-tumour roles by sponging miR-100 through the deactivation of PI3K/AKT and mTOR pathways in the renal carcinoma cell lines

Aims: To explore the roles and regulatory mechanisms of the circular RNA (circRNA)-hsa-circ-0072309 in CAKI-1 and ACHN cells. Methods: CAKI-1 and ACHN cells were transfected with hsa-circ-0072309 overproduction vector (circRNA) and microRNA-100 (miR-100) mimic or the corresponding controls. Cell viability was detected with the CCK-8. The protein expression levels of p53, c-Myc, cleaved-caspase-3/9, matrix metalloproteinase (MMP)-2/9, vimentin, AKT, PI3K and mTOR were individually determined through western blot. qRT-PCR was used to examine the expressions of hsa-circ-0072309 and miR-100. The apoptotic rate and the migration or invasion rates were separately determined by the annexin v-FITC/PI with a flow cytometer and modified two-chamber migration assay or millicell hanging cell culture. Results: The hsa-circ-0072309 was poorly expressed in tumor tissue. Abundant hsa-circ-0072309 induced the inhibitions of cell proliferation, migration and invasion, as well as the PI3K/AKT and the mTOR cascades but enhancement of apoptosis. circRNA stimulated the down-regulation of miR-100, which was low-expressed in tumour tissue and whose overproduction abolished the impacts of circRNA on these elements mentioned above. Conclusion: The hsa-circ-0072309 played anti-tumour roles by targeting miR-100 by blocking the PI3K/AKT and mTOR cascades in the CAKI-1 and ACHN cell lines.

High PI3K/mTOR and low MAPK/JNK activity results in decreased apoptosis and autophagy in nasal polyposis

Introduction

Nasal polyposis is a progressive inflammatory disease that reduces the quality of life. The role of apoptotic and autophagic pathways in nasal polyposis pathogenesis is not yet clearly known.

Objective

In this study we aimed to investigate apoptotic (MAPK/JNK), anti-apoptotic (PI3K/mTOR) and autophagic (LC3) pathways which are related each other in the nasal polyposis tissues.

Methods

Twenty patients with nasal polyps and fifteen patients going through an inferior turbinate reduction were included in this study. Patients with asthma, Samter triad and allergic fungal sinusitis were excluded from the study. The apoptotic and autophagic pathways were investigated in paraffin-embedded nasal tissue sections of 20 NP and 15 samples from inferior turbinate reduction by H&E and immunohistochemistry with h-score. TUNEL method with apoptotic index was used to demonstrate apoptotic cells.

Results

Decreased immunoreactivity of P38 MAPK (p < 0.005) and JNK (p < 0.005) were observed in nasal polyposis compared to material from inferior turbinate reduction. This decrease may indicate a downregulation of apoptosis as demonstrated by decreased TUNEL staining in nasal polyposis (p < 0.005). The PI3K (p < 0.002) and mTOR (p < 0.005) immunoreactivities were increased in nasal polyposis. This increase indicates a downregulation of autophagy as demonstrated by decreased LC3 staining in nasal polyposis (p < 0.001).

Conclusion

Deficient apoptosis and autophagy through MAPK/JNK and PI3K/mTOR pathways may have a role in the pathogenesis of nasal polyposis.

Role of IL-17A in Chronic Rhinosinusitis With Nasal Polyp

Purpose

Th17-associated inflammation is increased in chronic rhinosinusitis with nasal polyp (CRSwNP), and is associated with disease severity and steroid resistance. Overexpressed interleukin (IL)-17A affects CRSwNP by tissue remodeling, eosinophilic accumulation, and neutrophilic infiltration. We aimed to identify the role of IL-17A in CRSwNP and to evaluate the effects of anti-IL-17A blocking antibody on nasal polyp (NP) formation using a murine NP model. Moreover, we sought to investigate whether the inhibition of mechanistic target of the rapamycin (mTOR) signal pathway could suppress IL-17A expression and NP formation.

Methods

Human sinonasal tissues from control subjects and patients with chronic rhinosinusitis (CRS) were analyzed using immunohistochemistry (IHC) and immunofluorescence staining. The effects of IL-17A neutralizing antibody and rapamycin were evaluated in a murine NP model. Mouse samples were analyzed using IHC, quantitative real-time polymerase chain reaction, and enzyme-linked immunosorbent assay.

Results

IL-17A⁺ inflammatory cells were significantly increased in number in NP from patients with CRSwNP compared to that in uncinate process tissues from control subjects and patients with CRS without NP or CRSwNP. CD68⁺ M1 macrophages dominantly expressed IL-17A, followed by neutrophils and T helper cells, in NP tissues. Neutralization of IL-17A effectively reduced the number of NPs, inflammatory cytokines, and IL-17A-producing cells, including M1 macrophages. Inhibition of IL-17A via the mTOR pathway using rapamycin also attenuated NP formation and inflammation in the murine NP model.

Conclusions

IL-17A possibly plays a role in the pathogenesis of CRSwNP, the major cellular source being M1 macrophage in NP tissues. Targeting IL-17A directly or indirectly may be an effective therapeutic strategy for CRSwNP.

The role of autophagy in the overexpression of MUC5AC in patients with chronic rhinosinusitis

BACKGROUND

Autophagy is a lysosomal degradation pathway that protects the body and is essential for cell survival and differentiation. Mucins (MUCs) are important components of secreted mucus, mucin (MUC)5 AC is the major MUC secreted in the normal airway.

OBJECTIVE

Investigated the role of autophagy in pathogenic mucin (MUC)5 AC production during chronic rhinosinusitis (CRS).

METHODS

The expression of human neutrophil elastase (HNE) and the autophagic proteins microtubule-associated protein 1 light chain (LC)3B-II, c-Jun N-terminal kinase (JNK), c-Jun, and MUC5AC were analyzed in the sinonasal mucosa and human nasal epithelial cells (HNECs) using immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), and quantitative real-time polymerase chain reaction (qRT-PCR). Autophagic vacuoles were studied using transmission electron microscopy (TEM). Primary HNECs were treated with HNE, bafilomycin A1, and SP600125. In some experiments, cultured primary HNECs were transfected with small interfering RNAs (siRNAs) to target Beclin-1 (BECN1; BECN1-siRNA), autophagy-related gene 5 (Atg5; Atg5-siRNA), and c-Jun (c-Jun-siRNA). Cultured cells were analyzed using western blotting, qRT-PCR, and ELISA.

RESULTS

In CRS patients, both with and without nasal polyps, the expression levels of HNE, LC3B, JNK, c-Jun, and MUC5AC were upregulated. Bafilomycin A1 upregulated LC3B-II expression and inhibited MUC secretion in HNE-treated normal primary HNECs. Autophagosomes were observed in HNE-treated primary HNECs using TEM. HNE-induced secretion of MUC5AC was suppressed in normal primary HNECs by BECN1-siRNA, Atg5-siRNA, c-Jun-siRNA, and SP600125.

CONCLUSIONS

In HNE-induced CRS, autophagy increases the secretion of MUC5AC by promoting the phosphorylation of JNK and c-Jun.

The Role of Autophagy in Eosinophilic Airway Inflammation

Autophagy is a homeostatic mechanism that discards not only invading pathogens but also damaged organelles and denatured proteins via lysosomal degradation. Increasing evidence suggests a role for autophagy in inflammatory diseases, including infectious diseases, Crohn's disease, cystic fibrosis, and pulmonary hypertension. These studies suggest that modulating autophagy could be a novel therapeutic option for inflammatory diseases. Eosinophils are a major type of inflammatory cell that aggravates airway inflammatory diseases, particularly corticosteroid-resistant inflammation. The eosinophil count is a useful tool for assessing which patients may benefit from inhaled corticosteroid therapy. Recent studies demonstrate that autophagy plays a role in eosinophilic airway inflammatory diseases by promoting airway remodeling and loss of function. Genetic variant in the autophagy gene ATG5 is associated with asthma pathogenesis, and autophagy regulates apoptotic pathways in epithelial cells in individuals with chronic obstructive pulmonary disease. Moreover, autophagy dysfunction leads to severe inflammation, especially eosinophilic inflammation, in chronic rhinosinusitis. However, the mechanism underlying autophagy-mediated regulation of eosinophilic airway inflammation remains unclear. The aim of this review is to provide a general overview of the role of autophagy in eosinophilic airway inflammation. We also suggest that autophagy may be a new therapeutic target for airway inflammation, including that mediated by eosinophils.

Circular RNA hsa_circ_0072309 inhibits proliferation and invasion of breast cancer cells via targeting miR-492

Background

Although the number of circular RNAs (circRNAs) that has been identified in multiple cancer tissues continues to increase, the relationship between circRNA expression and carcinogenesis remains unknown. The role of hsa_circ_0072309 in breast cancer has remained undefined until now. In this study, we aimed to investigate the role of hsa_circ_0072309 in breast cancer progression.

Methods

hsa_circ_0072309 expression in breast cancer tissues was analyzed using qRT-PCR. A series of functional experiments were carried out to investigate hsa_circ_0072309 function in breast cancer development and its underlying molecular mechanisms.

Results

hsa_circ_0072309 expression in breast cancer tissues was upregulated relative to that in adjacent normal tissues. hsa_circ_0072309 could serve as a prognostic biomarker of breast cancer. hsa_circ_0072309 overexpression dramatically inhibited the proliferation, migration, and invasion of breast cancer cells in vitro. In vivo assays revealed that the ectopic expression of hsa_circ_0072309 repressed breast cancer growth. The results of our mechanistic studies indicated that hsa_circ_0072309 could act as the sponge of miR-492, which exhibited increased expression in breast cancer tissues. Hsa_circ_0072309 suppressed breast cancer cell proliferation, migration, and invasion by inhibiting miR-492.

Conclusion

Our findings revealed for the first time that the hsa_circ_0072309-miR-492 axis plays an essential role in breast cancer progression.

Autophagy deficiency in myeloid cells exacerbates eosinophilic inflammation in chronic rhinosinusitis

BACKGROUND

Eosinophilic inflammation is a major pathologic feature of chronic rhinosinusitis (CRS) and is frequently associated with severe refractory disease. Prostaglandin (PG) D₂ levels are increased in patients with CRS, and PGD₂ is an important contributing factor to eosinophilic inflammation. Autophagy has a pleiotropic effect on immune responses and disease pathogenesis. Recent studies suggest the potential involvement of autophagy in patients with CRS and the PG pathway.

OBJECTIVE

We sought to investigate whether altered function of autophagy is associated with eosinophilic inflammation and dysregulated production of PGD₂ in patients with CRS.

METHODS

We used myeloid cell-specific deletion of autophagy-related gene 7 (Atg7), which is vital for autophagy, and investigated the effects of impaired autophagy on eosinophilic inflammation in a murine model of eosinophilic chronic rhinosinusitis (ECRS). The effect of autophagy on PGD₂ production and gene expression profiles associated with allergy and the PG pathway were assessed.

RESULTS

We found that impaired autophagy in myeloid cells aggravated eosinophilia, epithelial hyperplasia, and mucosal thickening in mice with ECRS. This aggravation was associated with gene expression profiles that favor eosinophilic inflammation, T_H2 response, mast cell infiltration, and PGD₂ dysregulation. Supporting this, PGD₂ production was also increased significantly by impaired autophagy. Among other myeloid cells, macrophages were associated with autophagy deficiency, leading to increased IL-1β levels. Macrophage depletion or blockade of IL-1 receptor led to alleviation of eosinophilic inflammation and sinonasal anatomic abnormalities associated with autophagy deficiency.

CONCLUSION

Our results suggest that impaired autophagy in myeloid cells, particularly macrophages, has a causal role in eosinophilic inflammation and ECRS pathogenesis.

Interferon-γ-induced insufficient autophagy contributes to p62-dependent apoptosis of epithelial cells in chronic rhinosinusitis with nasal polyps

BACKGROUND

Autophagy is a lysosomal degradation pathway that is essential for cell survival, differentiation, and homeostasis. This study aimed to investigate the contribution of autophagy to the pathogenesis of CRS with nasal polyps (CRSwNP).

METHODS

The expression of autophagic proteins [microtubule-associated protein 1 light chain 3B (LC3B)-II, autophagy-related proteins (Atg), and Beclin 1], substrate proteins (p62 and ubiquitinated proteins), and apoptotic signaling molecules [cysteine-aspartic protease-3 and cysteine-aspartic protease-8, and poly-ADP-ribose polymerase] in the sinonasal mucosa and nasal epithelial cells (NECs) was detected by immunohistochemistry and Western blotting. Autophagic vacuoles were observed with transmission electron microscopy. BEAS-2B cells and NECs were treated with rapamycin, bafilomycin A1, or various cytokines. In some experiments, cultured NECs were transfected with small interfering RNA targeting p62 (sip62) or Atg5 (siAtg5). Cultured cells were analyzed with Western blotting and flow cytometry.

RESULTS

Although autophagic protein expression and autophagic vacuole formation were increased in both eosinophilic and noneosinophilic CRSwNP, particularly in NECs, there was also an up-regulation of substrate proteins and apoptotic signaling molecules. IFN-γ, but not IL-4, IL-13, or IL-17A, simultaneously enhanced LC3B-II and p62 levels as well as cell apoptosis in BEAS-2B cells and/or normal NECs. Bafilomycin A1 up-regulated the levels of LC3B-II and p62 in polyp NECs and IFN-γ-treated normal NECs. IFN-γ-induced apoptosis of normal NECs was exaggerated by bafilomycin A1 and siAtg5. Sip62 suppressed apoptosis of polyp NECs and IFN-γ-treated NECs. IFN-γ protein levels were increased in both eosinophilic and noneosinophilic CRSwNP.

CONCLUSIONS

IFN-γ induces activated but insufficient autophagy and thus contributes to a degree to p62-dependent apoptosis of NECs in CRSwNP.

Expression of decorin in intestinal tissues of mice with inflammatory bowel disease and its correlation with autophagy

The aim of this study was to investigate the expression of decorin (DCN) in the intestinal tissues of mice with inflammatory bowel disease (IBD) and its correlation with autophagy. The IBD mouse model was created by intrarectal injection of trinitrobenzene sulfonic acid. The pathology of colon tissues of the mice was examined using hematoxylin and eosin staining. Expression of DCN and the proteins associated with autophagy was detected using immunohistochemistry. Normal human colon mucosal epithelial cells (NCM460 cells) were transfected with DCN expression plasmid and the expression of DCN and autophagy-associated proteins was detected by western blot analysis. Cell apoptosis was studied using an Annexin V apoptosis detection assay and intracellular autophagosomes were observed using electron microscopy. The IBD mouse model was successfully established. Thickening, edema and inflammatory cell infiltration of the intestinal wall were observed in the IBD mice. The expression of DCN as well as the autophagy-associated proteins beclin 1 and LC3B, was increased in the intestinal tissues of the IBD mice. Furthermore, in the NCM460 cells transfected with DCN, the expression of beclin 1 and LC3B was upregulated, while p62 expression was downregulated. Intracellular autophagosomes were increased and apoptosis was decreased in the cells with DCN overexpression. Inhibition of autophagy reversed the effects of DCN on apoptosis. Therefore, DCN is able to induce autophagy and protect intestinal cells during the occurrence and development of IBD.

Immunomodulation and Disease Tolerance to Staphylococcus aureus

The Gram-positive bacterium Staphylococcus aureus is one of the most frequent pathogens that causes severe morbidity and mortality throughout the world. S. aureus can infect skin and soft tissues or become invasive leading to diseases such as pneumonia, endocarditis, sepsis or toxic shock syndrome. In contrast, S. aureus is also a common commensal microbe and is often part of the human nasal microbiome without causing any apparent disease. In this review, we explore the immunomodulation and disease tolerance mechanisms that promote commensalism to S. aureus.