Effect of Blomia tropicalis Allergen (Blo t 21) on Junctional Protein Expression in Human Bronchial Epithelial Cells

Shamsol Azman, Ain Nabila Syahira (2021) Effect of Blomia tropicalis Allergen (Blo t 21) on Junctional Protein Expression in Human Bronchial Epithelial Cells. [Project Paper] (Submitted)

Text FPSK2 2021 38.pdf Download (1MB)

Abstract

The airway epithelium acts as a physical barrier that primarily regulated by junctional proteins which restrict the passage of inhaled substances such as house dust mite (HDM) allergens. The epithelial barrier disruption through the degradation of junctional proteins by HDM allergens displaying proteolytic activity has been extensively reported in the literature. However, little is known on the other biological functions of HDM allergens such as the lipid binding protein on the effect of junctional protein expression. Blo t 21, a group 21 HDM allergen is one of the major allergens found in the HDM species Blomia tropicalis which displays structural homologies with the lipid binding protein Der p 5. Blo t 21 has been recognised as a major sensitizing protein with Ig-E binding frequency reaching more than 50% in HDM sensitized population. Despite the high sensitization frequency of this allergen, the effect of the Blo t 21 on the epithelial barrier function is still unknown. Objective: This study aimed to investigate the effect of Blo t 21 on the expression of junctional protein specifically occludin in a human bronchial epithelial cell line, namely 16HBE14o-. Methodology: 16HBE14o- cells were used as these cells express the principal intercellular tight junctional proteins. The cells were induced with recombinant Blo t 21 at the concentration of 20 μg/mL for 24 hours. The cell viability was determined using lactate dehydrogenase (LDH) activity assay. The effect of Blo t 21 on the protein expression of occludin was then assessed via Western Blot and the band intensity was analyzed by using ImageJ software. Results: No significant death of 16HBE-14o cell viability was observed between control and Blo t 21-induced groups. Blo t 21 (20 μg/mL) was shown to downregulate the protein expression of occludin in 16HBE14o- cells, as indicated by a significant reduction of the band intensity of occludin in Blo t 21-induced group (p < 0.05). Discussion: Based on the findings from LDH assay, no significant death was observed in cells induced with 20 μg/mL Blo t 21. This finding indicates that the regulatory effect on occludin expression was not arisen from the cytotoxicity exerted by Blo t 21 on 16HBE14o- cells. In term of protein expression, Blo t 21 significantly downregulated the protein expression of occludin by 54% as compared to the normal group. This finding is in line with an earlier study which proved that HDM allergen that was independent of proteolytic activity could exerted regulatory effect on tight junctional protein expression at gene level. Conclusion: In short, the present study signifies that Blo t 21 may capable of downregulating the expression of occludin. This finding further strengthens the speculation that nonproteolytic HDM allergens may interfere with the epithelial barrier integrity through the regulation of tight junctional protein expression. Nonetheless, the effects of Blo t 21 on the expression of other junctional proteins and the mechanisms underlying the regulatory effect of Blo t 21 should be further dissected in the future.

Item Type:	Project Paper
Faculty:	Faculty of Medicine and Health Science
Depositing User:	Ms. Nor Safa'aton Saidin
Date Deposited:	22 Aug 2023 07:51
Last Modified:	22 Aug 2023 07:51
URI:	http://psaspb.upm.edu.my/id/eprint/1146

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