title: Multiple caspases mediate acute renal cell apoptosis induced by bacterial cell wall components.
abstract: The stimulus for caspase-mediated renal cell apoptosis in septic acute renal failure (ARF) is unclear. To demonstrate the nephrotoxic effects of bacterial cell wall components, the anti-cellular activity of bacterial muropeptides (muramyl dipeptides), peptidoglycans, and lipopolysaccharides was investigated in rabbit kidney cells. Changes in the cell membrane (APOPercentage™ dye uptake), caspase activities, and DNA degradation were quantified colorimetrically and using densitometric assays and their inhibition by caspase-specific and pan-caspase inhibitors was determined. The onset and levels of APOPercentage™ dye-positive rabbit kidney cells, caspase activities, and DNA degradation were closely associated. Specific caspase-1, -2, -3, -4, -8, -10, and -12 inhibitors reduced caspase-3 activity by ≥40%, but only caspase-3 and -8-specific inhibitors reduced apoptotic DNA levels. Pan-caspase inhibitor Q-VD-OPh was 10-fold more effective at inhibiting rabbit kidney cell death, caspase activation, and DNA degradation than caspase-family inhibitor Z-VAD-FMK. Apoptosis was inhibited effectively by both pan-caspase inhibitors when applied early during the stimulus-to-response period. Multiple initiator and effector caspases were activated suggesting extrinsic, intrinsic, and endoplasmic reticulum/stress apoptotic pathway stimulation in rabbit kidney cells treated with bacterial cell wall components. The results provide in vitro support for bacterial cell wall-induced apoptosis as a pathogenic mechanism of renal cell death in septic ARF and support the potential prophylactic use of pan-caspase inhibitors to suppress septic ARF.
authors.affiliation: Department of Ophthalmology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA. mlangf@lsuhsc.edu
authors.forename: Marlyn P
authors.initials: MP
authors.lastname: Langford
authors.forename: David J
authors.initials: DJ
authors.lastname: McGee
authors.forename: Kathy H
authors.initials: KH
authors.lastname: Ta
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Redens
authors.forename: Donald E
authors.initials: DE
authors.lastname: Texada
mesh_terms: D000119:Acetylmuramyl-Alanyl-Isoglutamine; D058186:Acute Kidney Injury / Q000201:enzymology / Q000209:etiology* / Q000473:pathology; D000590:Amino Acid Chloromethyl Ketones; D000818:Animals; D017209:Apoptosis; D001424:Bacterial Infections / Q000150:complications* / Q000201:enzymology / Q000473:pathology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D002473:Cell Wall; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D007668:Kidney / Q000201:enzymology* / Q000473:pathology; D008070:Lipopolysaccharides; D010457:Peptidoglycan; D011804:Quinolines; D011817:Rabbits; D013997:Time Factors
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D008070:Lipopolysaccharides; D010457:Peptidoglycan; D011804:Quinolines; C468548:quinoline-val-asp(OMe)-CH2-OPH; D000119:Acetylmuramyl-Alanyl-Isoglutamine; D020169:Caspases