TET2 deficiency exacerbates nasal polypogenesis by inducing epithelial-to-mesenchymal transition

Serum exosomal miR-141-3p and miR-3679-5p levels associated with endotype and postoperative recurrence in chronic rhinosinusitis with nasal polyps

Background

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease. Exosomes were involved in different inflammatory diseases, but their roles in CRSwNP were poorly explored.

Method

We collected serum samples from 8 CRSwNP patients and 8 healthy controls (HC) and isolated their exosomes. MiRNA sequencing was performed for the exosome samples and differentially expressed miRNAs were identified. The top 3 differentially expressed exosomal miRNAs were confirmed in 2 validation cohorts, and their diagnostic values, predictive values for eosinophilic endotype, and recurrence were evaluated.

Results

Distinctive serum exosomal miRNA profiles were observed between CRSwNP and HC groups. Reverse transcription-polymerase chain reaction results in the first validation cohort revealed that serum exosomal miR-141-3p levels were increased, and miR-18a-5p and miR-3679-5p levels were decreased in the CRSwNP group compared to the HC group. These 3 miRNAs were further validated in the second validation cohort, and the results showed that miR-141-3p levels were elevated and miR-3679-5p levels were reduced in the serum exosomes in the eosinophilic CRSwNP group in comparison with the non-eosinophilic CRSwNP group. Receiver operating characteristic (ROC) curves highlighted that exosomal miR-141-3p and miR-3679-5p exhibited promising values for predicting the eosinophilic endotype. The patients in the second cohort were followed up for 2 years, and categorized into recurrence and non-recurrence groups. The serum exosomal miR-141-3p levels were increased and miR-3679-5p levels were reduced in the recurrence group in comparison with the non-recurrence group. ROC curves and Kaplan-Meier survival analysis revealed significant associations between the levels of exosomal miR-141-3p and miR-3679-5p and the risk of postoperative recurrence.

Conclusions

This study identified unique miRNA expression patterns in serum exosomes of CRSwNP patients. Circulating exosomal miR-141-3p and miR-3679-5p emerged as novel biomarkers for diagnosing CRSwNP, predicting the eosinophilic endotype, and forecasting postoperative recurrence.

E3 ubiquitin ligase NEDD4L inhibits epithelial-mesenchymal transition by suppressing the β-catenin/HIF-1α positive feedback loop in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyp (CRSwNP) is a refractory inflammatory disease with epithelial-mesenchymal transition (EMT) as one of the key features. Since ubiquitin modification has been shown to regulate the EMT process in other diseases, targeting ubiquitin ligases may be a potential strategy for the treatment of CRSwNP. In this study we investigated whether certain E3 ubiquitin ligases could regulate the EMT process in CRSwNP, and whether these regulations could be the potential drug targets as well as the underlying mechanisms. After screening the potential drug target by bioinformatic analyses, the expression levels of three potential E3 ubiquitin ligases were compared among the control, eosinophilic nasal polyp (ENP) and non-eosinophilic nasal polyp (NENP) group in clinical samples, and the significant decrement of the expression level of NEDD4L was found. Then, IP-MS, bioinformatics and immunohistochemistry studies suggested that low NEDD4L expression may be associated with the EMT process. In human nasal epithelial cells (hNECs) and human nasal epithelial cell line RPMI 2650, knockdown of NEDD4L promoted EMT, while upregulating NEDD4L reversed this effect, suggesting that NEDD4L inhibited EMT in nasal epithelial cells. IP-MS and Co-IP studies revealed that NEDD4L mediated the degradation of DDR1. We demonstrated that NEDD4L inhibited the β-catenin/HIF-1α positive feedback loop either directly (degrading β-catenin and HIF-1α) or indirectly (mediating DDR1 degradation). These results were confirmed in a murine NP model in vivo. This study for the first time reveals the regulatory role of ubiquitin in the EMT process of nasal epithelial cells, and identifies a novel drug target NEDD4L, which has promising efficacy against both ENP and NENP by suppressing β-catenin/HIF-1α positive feedback loop.

Downregulation of TET2 Contributes to Nasal Polypogenesis Through Hypoxia-Inducible Factor 1α-Mediated Epithelial-to-Mesenchymal Transition

OBJECTIVES

Hypoxia-inducible factor 1α (HIF1α) and Tet methylcytosine dioxygenase 2 (TET2) have been reported to mediate nasal polypogenesis through the epithelial-to-mesenchymal transition (EMT). Additionally, HIF1α can regulate the expression and function of TET2. However, the precise mechanism of how TET2 regulates the EMT through HIF1α mediation in nasal epithelial cells is still poorly understood.

METHODS

Nasal tissue samples were collected from patients with chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP), CRS without nasal polyps (CRSsNP), and controls. The expression of HIF1α and TET2 was detected using Western blotting and immunohistochemistry. EMT markers (E-cadherin and vimentin) were also evaluated by immunohistochemistry. Primary human nasal epithelial cells (hNECs) were stimulated with CoCl2 to mimic hypoxia. Vitamin C (VC), a TET2 non-specific activator, and small interfering RNA (siRNA) transfection of TET2 were used to further determine the role of TET2 in hypoxia-induced EMT. Finally, reactive oxygen species (ROS) and Nrf2 were measured to explore the downstream consequences of TET2 in hypoxic hNECs.

RESULTS

TET2 levels were lower in the nasal epithelium of CRSwNP patients and were positively correlated with E-cadherin but negatively correlated with vimentin in CRS. However, HIF1α exhibited the opposite pattern and was negatively correlated with TET2 expression. CoCl2-simulated hypoxia led to EMT and increased HIF1α in hNECs in vitro, with simultaneous downregulation of TET2 expression. Addition of VC activated TET2 expression in hNECs, but inhibited EMT and HIF1α expression. Furthermore, siRNA knockdown of TET2 contributed to the EMT in CoCl2-simulated hNECs despite the addition of VC. Finally, TET2 regulated the EMT in hypoxic hNECs through Nrf2 expression and ROS generation.

CONCLUSION

TET2 was negatively correlated with HIF1α and EMT in vivo. TET2 was downregulated by HIF1α, resulting in the EMT in CoCl2-hypoxic hNECs via regulation of oxidative stress in vitro. Hence, TET2 might provide a new therapeutic approach for CRSwNP.