Cryptosporidium parvumdisrupts intestinal epithelial barrier function via altering expression of key tight junction and adherens junction proteins

Abstract

Infection with the protozoan parasite Cryptosporidium parvum (CP) causes cryptosporidiosis, a widespread diarrhoeal disease. Impaired intestinal epithelial barrier function and increased permeability are most commonly associated with diarrhoeal diseases caused by enteric infections. However, studies on barrier disruption and underlying mechanisms in cryptosporidiosis are extremely limited. Epithelial tight junctions (TJs) and adherens junctions (AJs) are important in maintaining barrier integrity. Therefore, we examined the effects of CP infection on paracellular permeability and on the expression of the major TJ and AJ proteins utilising in vitro, ex vivo, and in vivo models. CP infection (0.5 × 10 oocysts/well in Transwell inserts, 24 hr) increased paracellular permeability (FITC-dextran flux) in Caco-2 cell monolayers and substantially decreased the protein levels of occludin, claudin 4, and E-cadherin. Claudin 3, zonula occludens-1 (ZO1) and α-catenin were also significantly decreased, whereas claudins 1 and 2 and β-catenin were not altered. Substantial downregulation of occludin, claudin 4, and E-cadherin was also observed in response to CP infection ex vivo in mouse enteroid-derived monolayers and in vivo in the ileal and jejunal mocosa of C57BL/6 mice. The mRNA levels of these proteins were also significantly decreased in CP-infected mouse ileum and jejunum but were unaltered in Caco-2 cells. Further, bafilomycin-A, an inhibitor of lysosomal proton pump, partially abrogated CP effects on occludin expression in Caco-2 cells, suggesting a potential role of posttranslational mechanisms, such as induction of protein degradation pathways, in mediating the effects of the parasite. Our studies suggest that disruption of barrier function via downregulation of specific key components of TJ and AJ could be a major mechanism underlying CP infection-induced diarrhoea.

Changes in the Microbiome of Cryptosporidium-Infected Mice Correlate to Differences in Susceptibility and Infection Levels

“…Subsequent studies in our laboratory with IFN-γ KO mice (which have higher parasite loads than IL-12 KO mice) have demonstrated significantly increased FITC-dextran levels in sera (data not shown). Increased permeability was observed in C. parvum infected cells using transwells [ 42 ] and C. parvum infection of Caco-2 cells has been reported to decrease levels of the tight junction proteins, occludin and claudin 4 [ 43 ]. Interestingly, increased levels of indole increase epithelial integrity [ 44 ].…”

Disruption of gut integrity and permeability contributes to enteritis in a fish-parasite model: a story told from serum metabolomics

“…Its interaction with epithelial cells directly induces pro-inflammatory responses and later on perturbs the TJ proteins to stimulate water and ion secretion [46]. The diarrhoea induced by the intracellular parasite Cryptosporidium parvum is due to an increased paracellular permeability associated with decreased levels of several TJ and AJ proteins in vitro and also to the downregulation of genes related to TJs and AJs in response to the infection in ex vivo and in vivo mouse models [47]. Similarly, the reduction in the intestinal barrier function induced by Giardia duodenalis implicates disruptions of several TJ proteins [48].…”

The Role of Probiotics and Prebiotics in the Prevention and Treatment of Obesity

“…Furthermore, goblet cells, which are simple columnar epithelial cells, secret a mucus able to separate the bacteria from the lumen, preventing colonization of the epithelium [140]. Therefore, epithelial barrier disruption will lead to different illnesses, such as celiac disease [141], inflammatory bowel disease [142], autoimmune diseases (e.g., type 1 diabetes) [143], or enteric infections [144]. As mentioned earlier in this review, abnormally increased gut permeability to bacteria and their products is a factor that further contributes to insulin resistance, oxidative stress, and a level of chronic low-grade inflammation, which, in turn, are associated with the development of obesity-related metabolic disturbances.…”