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Cryptosporidium parvum infection disrupts intestinal epithelial barrier function via decreasing expression of specific tight junction and adherens junction proteins
Author(s) -
KUMAR ANOOP,
Chaterjee Ishita,
Anbazhagan Arivarasu Natarajan,
Priyamvada Shubha,
Jayawardena Dulari,
Alrefai Waddah,
Borthakur Alip,
Dudeja Pradeep Kumar
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1043.1
Subject(s) - paracellular transport , tight junction , adherens junction , occludin , claudin , cryptosporidium parvum , barrier function , biology , cell junction , enterocyte , intestinal permeability , intestinal epithelium , transcellular , intestinal mucosa , microbiology and biotechnology , ileum , epithelium , immunology , small intestine , cadherin , cell , permeability (electromagnetism) , biochemistry , medicine , genetics , membrane
Background Enteric infection with the protozoan parasite Cryptosporidium parvum (CP) causes cryptosporidiosis, a widespread diarrheal disease. CP sporozoites released in the lumen invade epithelial cells of the small intestine and complete the infectious cycle therein. However, mechanisms of CP infection‐induced diarrhea are not fully understood. Decreased barrier function and increased epithelial permeability are known to contribute to the pathophysiology of diarrheal diseases caused by enteric infections. Intestinal epithelial barrier integrity is maintained by tight junctions (TJ) and adherens junctions (AJ). However, there are virtually no studies on CP effects on the expression of TJ and AJ proteins and their relevance to cryptosporidiosis. Aim The current studies were performed to examine the effects of CP infection on paracellular permeability and on the expression of occludin and claudins (key proteins of TJ assembly), and E‐cadherin (a major AJ protein) utilizing Caco‐2 cell monolayers, ex vivo mouse enteroids and in vivo mouse model. Methods Transepithelial resistance (TER) was measured by a Volt Ohm Meter, paracellular permeability was measured by apical to basolateral flux of FITC‐dextran, mRNA and protein levels of the TJ/AJ components were measured by real‐time RT‐PCR and immunoblotting/immunofluorescence, respectively. Results CP infection (0.5 × 10 6 oocysts/well) for 24 h decreased TER and increased paracellular permeability in Caco‐2 cell monolayers. CP infection significantly decreased protein levels of occludin, claudin‐4 and E‐cadherin with no effects on other claudins in Caco‐2 monolayers, mouse‐enteroid‐derived monolayers, and in the mucosa of ileum and jejunum in C57BL/6 mice (infected with 1.0 × 10 7 oocysts/mouse for 24 hr). mRNA levels of these three proteins were also significantly decreased in CP infected mouse ileum and jejunum, however, CP infection of Caco‐2 cells did not alter occludin and claudin‐4 mRNA levels. Further, bafilomycin, an inhibitor of lysosomal proton pump, partially abrogated CP‐induced downregulation of occludin expression, suggesting a potential role of post‐translational mechanisms such as protein degradation in CP‐induced downregulation of occludin in Caco‐2 cells. Conclusion Our studies suggest that disruption of barrier function via downregulation of specific key components of TJ and AJ could contribute to CP infection‐induced diarrhea. Support or Funding Information Supported by NIDDK and Department of Veterans Affairs