GENE EXPRESSION IN ACTIVATED HUMAN PMN

Polymorphonuclear leukocytes (PMN) are the most numerous host cells found
in periodontal pockets and acute inflammatory lesions. Their recruitment
and function is considered crucial to the prevention of periodontal
attachment loss and the systemic prevention of infection. For example,
individuals with compromised neutrophil function or numbers, e.g., in
Chediak-Higashi syndrome or neutropenia have increased prevalence and
severity of periodontal disease. Little is known about gene expression in
PMN because, until recently, mature PMN were not considered capable of
synthesizing new protein mediators and thus, unable to actively regulate
inflammatory processes. Recent evidence from our laboratory and others,
demonstrates that PMN are capable of expressing several important genes in
response to agents that prime PMN for increased oxidative metabolism.
Therefore, we formulated the hypothesis that agents known to induce
increase oxidative metabolism in PMN, e.g., chemotactic factors and
cytokines, also induced limited gene expression in PMN. In order to
address this hypothesis, we propose to: 1) Characterize the chemotactic factor (fmlp and C5a) and cytokine (Il-1
and TNF) induction of mRNA expression of genes associated with PMN function
including a) cytokines known to be inducible in PMN. b) genes associated with PMN activation, i.e., c-fos, c-jun, myristoylated,
alanine-rich C kinase substrate. c) genes associated with PMN granules, e.g., gelatinase, elastase, and
defensin. 2) Examine the repertoire of chemotactic factor and cytokine induced gene
expression a) at the protein level with polyacrylamide gel electrophoresis of
radiolabelled newly synthesized proteins. b) at the molecular level by constructing and screening cDNA libraries from
induced PMN. From these cDNA libraries we expect to identify expression of
known genes never before associated with PMN and genes never previously
identified. Thus, from these studies, we hope to bring new insight as to the scope of
gene expression in PMN and this will provide important clues as to how PMN
function may be altered to improve their function in inflammatory exudates,
e.g., in periodontal disease.