MEX3B inhibits collagen production in eosinophilic nasal polyps by downregulating epithelial cell TGFBR3 mRNA stability.

Although the expression of Mex3 RNA-binding family member B (MEX3B) is upregulated in human nasal epithelial cells (HNECs) predominately in the eosinophilic chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) subtype, its functions as an RNA binding protein in airway epithelial cells remain unknown. Here, we revealed the role of MEX3B based on different subtypes of CRS and demonstrated that MEX3B decreased the TGF-β receptor III (TGFBR3) mRNA level by binding to its 3' UTR and reducing its stability in HNECs. TGF-βR3 was found to be a TGF-β2-specific coreceptor in HNECs.

Endoplasmic reticulum stress promotes local immunoglobulin E production in allergic rhinitis.

Background: The role of endoplasmic reticulum (ER) stress in the pathogenesis of allergic rhinitis (AR) remains elusive.

Methods: Real-time polymerase chain reaction (RT-PCR), immunohistochemistry, and western blotting analyses were performed to detect the expression of ER stress and unfolded protein response markers: 78-kDa glucose-regulated protein (GRP78), C/EBP homologous protein (CHOP), activating transcription factor 6 (ATF6α), spliced X-box binding protein 1 (sXBP-1), and phosphorylated eukaryotic initiation factor 2α (-eIF2α), in inferior turbinate tissue samples from patients with AR and non-AR controls. Nasal tissues from patients with AR were cultured ex vivo and treated with 4-phenylbutyric acid (4-PBA), an ER stress inhibitor.