Submitted on January 11, 2002
Accepted on December 14, 2002
Oxidative stress-induced cell death of human oral neutrophils
Eisuke F Sato1*, Masahiro Higashino1, Kazuo Ikeda2, Wake Ryotaro1, Mitsuyoshi Matsuo3, Kozo Utsumi4, and Masayasu Inoue1
1 Department of Biochemistry and Molcular Pathology, Osaka City University Medical School, Osaka, Japan
2 Department of Anatomy, Osaka City University Medical School, Osaka, Japan
3 Deoartment of Biology, Konan University, Kobe, Japan
4 Institute for Medical Research, Center for Adult Diseases, Kurashiki, Japan
* To whom correspondence should be addressed. E-mail: sato{at}med.osaka-cu.ac.jp.
Polymorphonuclear leukocytes (PMN) play crucial roles in protecting hosts against invading microbes and in the pathogenesis of inflammatory tissue injury. Although PMN migrate into mucosal layers of digestive and respiratory tracts, only limited information is available of their fate and function in situ. We previously reported that, unlike circulating PMN (CPMN), PMN in the oral cavity spontaneously generate superoxide radical and nitric oxide (NO) in the absence of any stimuli. When cultured for 12 hr under physiological conditions, oral PMN (OPMN) showed morphological changes which are characteristic of those of apoptosis. Upon agarose gel electrophoresis, nuclear DNA samples isolated from OPMN revealed ladder-like profiles characteristic of nucleosomal fragmentation. L-Cysteine, reduced glutathione (GSH), and herbymycin A, a protein tyrosine kinase inhibitor, suppressed the activation of caspase-3 and apoptosis of OPMN. Neither thiourea, superoxide dismutase (SOD), nor catalase inhibited the activation of caspase-3 and apoptosis. Moreover, Ac-DEVD-CHO, inhibitor for caspase-3, inhibited the fragmentation of DNA. These results suggested that oxidative stress and/or tyrosine-kinase, dependent pathway(s) activated caspase-3 in OPMN, thereby inducing their apoptosis.
