Background: Cold exposure can trigger asthma attacks. However, the underlying mechanism is yet to be elucidated. We hypothesize that low temperature reduces occludin expression and compromises airway epithelial barrier function, which, in turn, results in asthma exacerbation. Methods: We examined occludin expression in Beas-2B cells exposed to either 29 °C or 37 °C. The following drugs were administered prior to cold treatment: MG132 (a proteasome inhibitor), cycloheximide (a protein synthesis inhibitor), HC-067047 plus GSK2193874 (transient receptor potential vanilloid 4 [TRPV4] antagonists), or C4-ceramide (an SGK1 activator). siNedd4-2 was transfected into Beas-2B cells to investigate the role of Nedd4-2 in mediating cold-induced occludin instability. In animal experiments, we treated ovalbumin (OVA)-induced asthmatic mice with either a thermoneutral temperature of 30 °C or repeated cold stress (10 °C, 6 h/day) for 2 weeks. Either GSK2193874 or C4-ceramide was administered during the cold treatment. After a final OVA challenge, pulmonary permeability, serum IgE levels, and lung inflammation were assessed. Results: Treatment at 29 °C for 1−9 h significantly reduced Beas-2B cell occludin expression, which was rescued upon treatment with MG132, HC-067047 plus GSK2193874, C4-ceramide, or the Nedd4-2 knockdown. Notably, low temperatures affected occludin stability through SGK1/Nedd4-2-dependent proteolysis. In vivo analyses revealed that repeated cold exposure compromised the airway epithelial barrier function and exacerbated lung inflammation in mice, which was partially attenuated by the GSK2193874 or C4-ceramide injection. Conclusions: We identified a new mechanism underlying cold-induced asthma exacerbation that may involve SGK1/Nedd4-2-mediated occludin proteolysis, resulting in epithelial barrier dysfunction.

Background: Growing evidence from observational studies suggests a link between Allergic [rhinitis](https://www.sciencedirect.com/topics/neuroscience/rhinitis) (AR) and psychiatric disorders; whether these associations represent causal relationships remains uncertain. Methods: We performed bi-directional two-sample mendelian randomization (MR) using summary statistics from European genome-wide association studies to examine evidence of causality, specificity and direction of association of AR with 11 different psychiatric disorders or relevant traits. MR was conducted using the inverse-variance weighted method (IVW), MR-Egger and weighted median methods. Sensitivity analyses included the MR-Egger regression and MR pleiotropy residual sum and outlier test. Results: AR from 2 different GWAS data was positively associated with bipolar disorder (OR=1.649, 95% CI: 1.077-2.526; P=0.021; OR=1.599; 95%CI 1.058-2.417; P=0.026). AR was also associated with major depressive disorder (OR=1.539; 95%CI 1.007-2.353; P=0.047). There were no significant association between AR and other 9 psychiatric disorders. Bidirectional analyses showed that bipolar disorder is negatively associated with AR (OR=0.964; 95%CI: 0.936-0.993; P=0.015). There was no evidence for potential causal schizophrenia and effects of attention deficit/hyperactivity disorder on risk of AR by MR method, but, MR pleiotropy residual outlier test suggested that attention deficit/hyperactivity disorder is negatively associated with AR after outlier correction (OR=0.976, 95%CI: 0.958-0.995, P=0.012). Conclusions: This MR study indicated that AR was a causal risk factor for bipolar disorder and major depressive disorder, but not for other psychiatric disorders. Bipolar disorder and attention deficit/hyperactivity disorder may be a protective factor for AR. Further studies could be carried out to leverage these new found insight into better clinical and experimental research in AR and psychiatric disorders.

Background: Milk allergy commonly occurs in children, mainly caused by casein (CAS) protein. Neutrophil-activating protein (NAP) of Helicobacter pylori plays an immunomodulatory role with potential to suppress Th2-type immune responses. Bacillus subtilis spores are commonly used as oral vectors for drug delivery. We hypothesized that recombinantly expressed NAP on B. subtilis spores could be an effective treatment for CAS allergy. Methods: After CAS sensitization, mice were orally administered B. subtilis spores expressing recombinant NAP for 6 weeks. Allergic symptoms and parameters were evaluated after CAS challenge via gavage, including allergic inflammation, splenic cytokines, and serum-specific antibodies. Protein levels of Toll-like receptor 2 (TLR2) and c-JUN in the jejunum tissue were measured by western blot. Bone marrow-derived macrophages (BMDMs) were stimulated with inactivated NAP spores to measure the influence on cytokine profiles in vitro. Results: NAP recombinant spore treatment significantly reduced allergic symptoms and intestinal inflammation. Interleukin-12 and interferon-gamma levels increased, whereas serum CAS-specific IgG1 and IgE levels decreased. TLR2 and c-JUN expression levels were elevated in the jejunal tissue. Inactivated NAP spores polarized BMDMs to the M1 phenotype and enhanced cytokine expression, which were inhibited by a TLR2 neutralizing antibody. Conclusions: NAP offers a new strategy in the treatment of CAS allergy by inhibiting the Th2 response, while eliciting macrophages to activate the TLR2-dependent signaling pathway and promote Th1 immune responses.

Background: We have previously demonstrated that benzo(a)pyrene (BaP) co-exposure with dermatophagoides group 1 allergen (Der f 1) can potentiate Der f 1-induced airway inflammation. We sought to investigate the molecular mechanisms underlying the potentiation of BaP exposure on Der f 1-induced airway inflammation. Methods: BaP co-exposure with Der f 1-induced activation of TGFβ1 signaling was analyzed in airway epithelial cells (HBECs) and in asthma mouse model. The role of aryl hydrocarbon receptor (AhR) and RhoA in BaP co-exposure-induced TGFβ1 signaling was investigated. AhR binding sites in RhoA were predicted and experimentally confirmed by luciferase reporter assays. The role of RhoA in BaP co-exposure-induced airway hyper-responsiveness (AHR) and allergic inflammation was examined. Results: BaP co-exposure potentiates Der f 1-induced TGFβ1 signaling activation in HBECs and in the airways of asthma mouse model. The BaP co-exposure-induced the activation of TGFβ1 signaling was attenuated by either AhR antagonist CH223191 or AhR knockdown in HBECs. Furthermore, AhR knockdown led to the reduction of BaP co-exposure-induced active RhoA. Inhibition of RhoA signaling with fasudil, a RhoA/ROCK inhibitor, suppressed BaP co-exposure-induced TGFβ1 signaling activation. This was further confirmed in HBECs expressing constitutively active RhoA (RhoA-L63) or dominant negative RhoA (RhoA-N19). Luciferase reporter assays showed prominently increased promoter activities for the AhR binding sites in the promoter region of RhoA. Inhibition of RhoA suppressed co-exposure-induced AHR, Th2-associated airway inflammation and TGFβ1 signaling activation in asthma. Conclusions: Our studies identified a functional axis of AhR-RhoA that regulates TGFβ1 signaling activation, leading to allergic airway inflammation and asthma.