Open AccessCryptosporidium parvum infection induces autophagy in intestinal epithelial cells
Author(s) -
Priyamvada Shubha,
Jayawardena Dulari,
Bhalala Jeet,
Kumar Anoop,
Anbazhagan Arivarasu N.,
Alrefai Waddah A.,
Borthakur Alip,
Dudeja Pradeep K.
Publication year - 2021
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/cmi.13298
Subject(s) - autophagy , biology , microbiology and biotechnology , cryptosporidium parvum , pi3k/akt/mtor pathway , adherens junction , autophagosome , phagosome , tight junction , intracellular , signal transduction , cell , biochemistry , cadherin , apoptosis
Autophagy, a process of degradation and recycling of macromolecules and organelles to maintain cellular homeostasis, has also been shown to help eliminate invading pathogens. Conversely, various pathogens including parasites have been shown to modulate/exploit host autophagy facilitating their intracellular infectious cycle. In this regard, Cryptosporidium parvum (CP), a protozoan parasite of small intestine is emerging as a major global health challenge. However, the pathophysiology of cryptosporidiosis is mostly unknown. We have recently demonstrated CP‐induced epithelial barrier disruption via decreasing the expression of specific tight junction (TJ) and adherens junction (AJ) proteins such as occludin, claudin‐4 and E‐cadherin. Therefore, we utilised confluent Caco‐2 cell monolayers as in vitro model of intestinal epithelial cells (IECs) to investigate the potential role of autophagy in the pathophysiology of cryptosporidiosis. Autophagy was assessed by increase in the ratio of LC3II (microtubule associated protein 1 light chain 3) to LC3I protein and decrease in p62/SQSTM1 protein levels. CP treatment of Caco‐2 cells for 24 hr induced autophagy with a maximum effect observed with 0.5 × 10 6 oocyst/well. CP decreased mTOR (mammalian target of rapamycin, a suppressor of autophagy) phosphorylation, suggesting autophagy induction via mTOR inactivation. Measurement of autophagic flux utilizing the lysosomal inhibitor chloroquine (CQ) showed more pronounced increase in LC3II level in cells co‐treated with CP + CQ as compared to CP or CQ alone, suggesting that CP‐induced increase in LC3II was due to enhanced autophagosome formation rather than impaired lysosomal clearance. CP infection did not alter ATG7, a key autophagy protein. However, the decrease in occludin, claudin‐4 and E‐cadherin by CP was partially blocked following siRNA silencing of ATG7, suggesting the role of autophagy in CP‐induced decrease in these TJ/AJ proteins. Our results provide novel evidence of autophagy induction by CP in host IECs that could alter important host cell processes contributing to the pathophysiology of cryptosporidiosis.