Epithelial cells and adhesion molecules

CTNNAL1 promotes the structural integrity of bronchial epithelial cells through the RhoA/ROCK1 pathway

Adhesion molecules play critical roles in maintaining the structural integrity of the airway epithelium in airways under stress. Previously, we reported that catenin alpha-like 1 (CTNNAL1) is downregulated in an asthma animal model and upregulated at the edge of human bronchial epithelial cells (HBECs) after ozone stress. In this work, we explore the potential role of CTNNAL1 in the structural adhesion of HBECs and its possible mechanism. We construct a CTNNAL1 ‒/‒ mouse model with CTNNAL1-RNAi recombinant adeno-associated virus (AAV) in the lung and a CTNNAL1-silencing cell line stably transfected with CTNNAL1-siRNA recombinant plasmids. Hematoxylin and eosin (HE) staining reveals that CTNNAL1 ‒/‒ mice have denuded epithelial cells and structural damage to the airway. Silencing of CTNNAL1 in HBECs inhibits cell proliferation and weakens extracellular matrix adhesion and intercellular adhesion, possibly through the action of the cytoskeleton. We also find that the expressions of the structural adhesion-related molecules E-cadherin, integrin β1, and integrin β4 are significantly decreased in ozone-treated cells than in vector control cells. In addition, our results show that the expression levels of RhoA/ROCK1 are decreased after CTNNAL1 silencing. Treatment with Y27632, a ROCK inhibitor, abolished the expressions of adhesion molecules induced by ozone in CTNNAL1-overexpressing HBECs. Overall, the findings of the present study suggest that CTNNAL1 plays a critical role in maintaining the structural integrity of the airway epithelium under ozone challenge, and is associated with epithelial cytoskeleton dynamics and the expressions of adhesion-related molecules via the RhoA/ROCK1 pathway.

Wound repair and proliferation of bronchial epithelial cells regulated by CTNNAL1

Adhesion molecules play vital roles in airway hyperresponsiveness (AHR) or airway inflammation. Our previous study indicated that adhesion molecule catenin alpha-like 1 (CTNNAL1) is relevant closely to asthma susceptibility, but its biological function or significance is still unclear. In the present study, we observed the temporal and spatial distribution of CTNNAL1 expression in mouse lung tissue with the OVA-sensitized asthma model and found that the level of CTNNAL1 mRNA showed a prominent negative correlation with pulmonary resistance (R(L)). To study the function of CTNNAL1 in airway, effects of CTNNAL1 on proliferation and wound repair activity of human bronchial epithelial cells (HBEC) was investigated with antisense oligonucleotide (ASO) technique. The results showed that: (1) CTNNAL1 ASO could decelerate the repairing velocity and proliferation of HBEC; (2) CTNNAL1 expression was increased on the edge cells of mechanic wounded area in culture; (3) extracellular matrix component fibronectin (Fn) obviously promoted wound repair activity and proliferation of HBEC, which could be blocked by CTNNAL1 ASO; (4) Western blot showed that Fn could promote FAK phosphorylation, which also be inhibited by CTNNAL1 ASO. In conclusion, the level of CTNNAL1 mRNA expression is highly correlated to airway resistance; CTNNAL1 may contribute to the wound repair and proliferation of HBEC. Furthermore, it may serve to Fn mediated cell-extracellular adhesion and its signal transduction.

The role of conjunctival epithelial cells in chronic ocular allergic disease

Recent evidence suggests that mucosal epithelial cells are capable of actively participating in immune reactions via expression of surface antigens, such as adhesion molecules, and synthesis of cytokines. This appears to be important in the pathophysiology of non-ocular allergic disorders. The objectives of the experiments were to compare the expression of HLA-DR, ICAM-I and pro-allergic cytokines in conjunctival epithelial cells in the different chronic ocular allergic disorders with each other and with normal subjects. Conjunctiva from normal patients (n=10) and patients with vernal keratoconjunctivitis (VKC, n=10), atopic keratoconjunctivitis (AKC, n=10) and contact lens-associated giant papillary conjunctivitis (GPC, n=10) were examined by immunohistochemistry. Epithelial cell staining for surface antigens and cytokines was graded by one masked observer using a four point scale based on the percentage of epithelial cells staining positive. There was no expression of ICAM-1 or HLA-DR in the normal conjunctival epithelial cells, but both antigens were induced on conjunctival epithelial cells in the allergic tissue, and there was greater expression in AKC and VKC compared with GPC. Cytokines IL-6, IL-8, RANTES and TNF-alphaall localised to normal conjunctival epithelial cells. RANTES was upregulated in all the allergic disorders and IL-8 was upregulated in GPC. IL-3 and GM-CSF were not expressed in normal conjunctival epithelial cells. GM-CSF was expressed in all disorders and there was greater expression in AKC compared with GPC and VKC. IL-3 was expressed only in AKC and VKC epithelial cells. These results suggest that conjunctival epithelial cells play an important pro-inflammatory role in chronic ocular allergic diseases; ICAM-1 may allow epithelial cells to recruit, retain and locally concentrate leukocytes; the presence of HLA-DR raises the question of conjunctival epithelial cell antigen presentation. The epithelial cytokines which are upregulated are known to promote eosinophilic inflammation and are typical of allergic inflammation. The differences in cytokine patterns may be exploitable for future therapy.