Temporal Changes in Caspase-1 and Caspase-8 Activities Following Brain Hypoxia With and Without Src kinase Inhibition in a Piglet Animal Model.
The Src family kinases are a family of intracellular, non-receptor tyrosine kinases that are involved in a variety of cellular functions including the regulation of inflammation and apoptosis after brain hypoxia. Caspase-1 (C1) activates IL-1β through the formation of complex structures, the inflammasomes, while caspase-8 (C8) is part of the extrinsic apoptotic pathway. C8 has been found to directly activate the production of IL-1β. Previously, we observed that C1 and IL-1β are increased in the acute phase after hypoxia in the brain of piglets, but they follow a different pattern long term, with C1 remaining activated throughout the period of observation, while IL-1β returning to baseline at 15 days. Src kinase inhibition ameliorated the activation of C1 and IL-1β early, but did not appear to have any effect long term. Prompted by these findings, we assessed the changes that occur over time (1 h and 15 days) in C1 and C8 activities after brain hypoxia as well as the effect of pretreatment with a Src kinase inhibitor, PP2 on these biochemical markers. Enzymatic activities were determined by spectrophotometry with measurements of C1 and C8 in each cytosolic brain sample (N = 4 in each group). We found that C1 and C8 activities increase in the acute phase following hypoxia in the brain of newborn piglets, with C8 relatively more than C1 (C8/C1 ratio increased from 2:1 as baseline to 3:1 in hypoxia). Fifteen days after hypoxia C8/C1 ratio decreased to about 1:1. In piglets that were pretreated with a Src kinase selective inhibitor (PP2) and then subjected to hypoxia, the C8/C1 ratio early increase was not observed. Immediately after hypoxia C8 and C1 follow a similar pattern of increase while long term this appears to dissociate. We propose that following this experimental methodology, the previously observed IL-1β production after hypoxia might be associated with C8 rather than C1 and that Src kinase is involved in the above process.
Division of Neonatology, Department of Pediatrics, Texas Tech University Health Sciences Center, Odessa, TX, 79763, USA. dimitrios.angelis@ttuhsc.edu.|Department of Pediatrics, Drexel University and St. Christopher's Hospital for Children, Philadelphia, PA, USA. dimitrios.angelis@ttuhsc.edu.
Dimitrios
D
Angelis
Department of Pediatrics, Miami Miller School of Medicine, Jackson Memorial Hospital, Miami, FL, USA.|Department of Pediatrics, Drexel University and St. Christopher's Hospital for Children, Philadelphia, PA, USA.
Tania D
TD
Fontánez Nieves
Department of Pediatrics, Drexel University and St. Christopher's Hospital for Children, Philadelphia, PA, USA.
Maria
M
Delivoria-Papadopoulos
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects; D020170:Caspase 1 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D002534:Hypoxia, Brain / Q000201:enzymology*; D053583:Interleukin-1beta / Q000096:biosynthesis; D010725:Phosphocreatine / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034421:Sus scrofa; D019061:src-Family Kinases / Q000037:antagonists & inhibitors*
D053583:Interleukin-1beta; D047428:Protein Kinase Inhibitors; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D019061:src-Family Kinases; D053181:Caspase 8; D020170:Caspase 1
Apoptosis; Caspase-1; Caspase-8; Hypoxic ischemic brain injury; Neuro-inflammation; Newborn piglet; PP2; Src kinase