Protective effects of anti-C5a in sepsis-induced thymocyte apoptosis.
Multiorgan apoptosis occurs during sepsis. Following cecal ligation and puncture (CLP) in rats, thymocytes underwent apoptosis in a time-dependent manner. C5a blockade dramatically reduced thymocyte apoptosis as measured by thymic weight, binding of annexin V to thymocytes, and laddering of thymocyte DNA. When C5a was generated in vivo by infusion of purified cobra venom factor (CVF), thymocyte apoptosis was significantly increased. Similar results were found when CVF was injected in vivo during the early stages of CLP. In animals 12 hours after induction of CLP, there was an increase in the activities of caspase-3, -6, and -9, but not caspase-1 and -8. Cytosolic cytochrome c levels increased by twofold, whereas mitochondrial levels showed a 50% decrease. Western blot analysis revealed that the content of Bcl-X(L) (but not of Bcl-2, BAX, Bad, and Bim) significantly decreased in thymocytes after CLP. C5a blockade in the sepsis model almost completely inhibited caspase-3, -6, and -9 activation, significantly preserved cytochrome c in the mitochondrial fraction, and restored Bcl-X(L) expression. These data suggest that systemic activation of complement induces C5a-dependent apoptosis of thymocytes and that the blockade of C5a during sepsis rescues thymocytes from apoptosis.
Guo
R F
RF
Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0602, USA.
Huber-Lang
M
M
Wang
X
X
Sarma
V
V
Padgaonkar
V A
VA
Craig
R A
RA
Riedemann
N C
NC
McClintock
S D
SD
Hlaing
T
T
Shi
M M
MM
Ward
P A
PA
D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000096:biosynthesis; D053148:Caspase 3; D053178:Caspase 6; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D015936:Complement C5a / Q000276:immunology / Q000378:metabolism*; D003574:Cytochrome c Group / Q000378:metabolism; D004789:Enzyme Activation; D008297:Male; D008565:Membrane Proteins; D008928:Mitochondria / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009929:Organ Size; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D011817:Rabbits; D051381:Rats; D020318:Rats, Long-Evans; D018805:Sepsis / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism*; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
D051017:Apoptosis Regulatory Proteins; C494821:Bad protein, rat; C494828:Bax protein, rat; D000072224:Bcl-2-Like Protein 11; C494813:Bcl2l1 protein, rat; C000606778:Bcl2l11 protein, rat; D002352:Carrier Proteins; D003574:Cytochrome c Group; D008565:Membrane Proteins; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; D015936:Complement C5a; C505410:Casp3 protein, rat; C505518:Casp6 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053178:Caspase 6; D053453:Caspase 9; D020169:Caspases