title: Aeromonas hydrophila induced head kidney macrophage apoptosis in Clarias batrachus involves the activation of calpain and is caspase-3 mediated.
abstract: The mechanism of macrophage cytotoxicity induced by Aeromonas hydrophila is yet unresolved. We observed A. hydrophila induces Head Kidney Macrophage (HKM) apoptosis in Clarias batrachus, as evident from Hoechst 33342 and AnnexinV-Propidium Iodide staining and presence of oligonucleosomal DNA ladder. Initiation of apoptosis required the bacteria to be alive, be actively phagocytosed into HKM and was dependent on host proteins. Elevated cytosolic calcium and consequent calpain activity that declined following pre-incubation with EGTA, verapamil and nifedipine implicates the role of calcium influx through voltage gated calcium channels and calpain in A. hydrophila-induced HKM apoptosis. Though, calpain-1 and -2 were involved, calpain-2 appeared to be more important in the process. EGTA, verapamil, nifedipine and calpain-2 inhibitor reduced caspase-3 activity and apoptosis. We conclude that A. hydrophila alters cytosolic calcium homeostasis initiating the activation of calpains, more specifically calpain-2, which leads to caspase-3 mediated HKM apoptosis in C. batrachus.
authors.affiliation: Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi 110 007, India.
authors.forename: Chaitali
authors.initials: C
authors.lastname: Banerjee
authors.forename: Ramansu
authors.initials: R
authors.lastname: Goswami
authors.forename: Gaurav
authors.initials: G
authors.lastname: Verma
authors.forename: Malabika
authors.initials: M
authors.lastname: Datta
authors.forename: Shibnath
authors.initials: S
authors.lastname: Mazumder
mesh_terms: D016980:Aeromonas hydrophila; D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism*; D002397:Catfishes; D005393:Fish Diseases / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D029941:Fish Proteins / Q000378:metabolism*; D016905:Gram-Negative Bacterial Infections / Q000276:immunology / Q000378:metabolism / Q000382:microbiology / Q000662:veterinary*; D060226:Head Kidney / Q000166:cytology* / Q000276:immunology; D008264:Macrophages / Q000166:cytology* / Q000276:immunology
chemical_list: D029941:Fish Proteins; D002154:Calpain; D053148:Caspase 3; D002118:Calcium