Pollen proteolytic enzymes degrade tight junctions

Runswick, Sarah, Mitchell, Thomas, Davies, Paul, Robinson, Clive, and Garrod, David R. (2007) Pollen proteolytic enzymes degrade tight junctions. Respirology, 12 (6). pp. 834-842.

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Background and objective: Asthma and allergic rhinitis are significant, increasing causes of morbidity worldwide. Pollen, a major cause of seasonal rhinitis/conjunctivitis, carries proteolytic enzymes on its surface. We showed previously that peptidase allergens from house dust mites compromise epithelial barrier function by degrading the extracellular domains of the tight junction proteins, occludin and claudin, thus facilitating allergen delivery across epithelial layers. In this study, we aimed to determine whether peptidases from allergenic pollens should similarly be considered to have a role in disrupting tight junctions.

Methods: Diffusates from stored pollen of Giant Ragweed, White Birch and Kentucky Blue Grass, and fresh pollen from Easter Lily were applied to confluent monolayers of Madin-Darby canine kidney (MDCK) and Calu-3 cells in serum-free medium. Immunofluorescence was performed for the tight junction proteins, occludin, claudin-1 and ZO-1. The effect of pollen diffusate on occludin was studied by Western blotting, and enzymatic activity in the diffusates was demonstrated by zymography. The ability of protease inhibitors to block the action of the diffusate on tight junctions was investigated.

Results: Diffusates from all four allergenic pollens caused loss of immunofluorescence labelling for tight junction proteins on MDCK and Calu-3 cells. The effect was blocked by inhibitors of serine and cysteine proteases. Degradation of occludin was demonstrated by Western blotting and zymography indicated that diffusates contain proteolytic activity.

Conclusions: Pollen peptidases directly or indirectly disrupt epithelial tight junctions, and this activity should be considered as a possible mechanism for facilitating allergen delivery across epithelia.

Item ID: 2929
Item Type: Article (Research - C1)
ISSN: 1440-1843
Keywords: allergy; asthma; pollen; proteolytic enzyme; rhinitis; tight junction
Additional Information:

Date Deposited: 23 Sep 2009 02:05
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1117 Public Health and Health Services > 111717 Primary Health Care @ 100%
SEO Codes: 92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920412 Preventive Medicine @ 100%
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