title: Induction of human beta-defensin-2 expression in human astrocytes by lipopolysaccharide and cytokines.
abstract: Defensins are cationic peptides with broad-spectrum antimicrobial activity. They are members of a supergene family consisting of alpha and beta subtypes and each subtype is comprised of a number of different isoforms. For example, human alpha-defensin (HAD) has six isoforms, which are expressed by polymorphonuclear leukocytes and Paneth cells. In contrast, human beta-defensin (HBD) has two isoforms that are expressed by epithelial cells of the skin, gut, respiratory and urogenital tracts. Recently, HBD-1 was detected in human brain biopsy tissue. However, little is known about the expression of HBD-1 or HBD-2 in the CNS and whether neural cells can secrete these peptides. For the present study, human astrocyte, microglial, meningeal fibroblast and neuronal cultures were probed for the expression of HBD-1 and HBD-2 mRNA and protein. Each cell type was either maintained in tissue culture medium alone or in medium containing lipopolysaccharide (LPS) at concentrations ranging from 0.1 to 1 microgram/mL, interleukin-1 beta (IL-1beta) at 1-50 ng/mL, or tumor necrosis factor alpha (TNF-alpha) at the same concentrations. The expression of HBD-1 and HBD-2 mRNAs was monitored by RT-PCR. The cDNA products were sequenced to characterize the gene product. HBD-2 protein was detected by immunoblot, immunoprecipitation and immunocytochemistry. Results of these studies showed that HBD-1 mRNA was detected in all cell cultures except in those enriched for neurons. In contrast, HBD-2 mRNA was detected only in astrocyte cultures that were treated with LPS, IL-1beta or TNF-alpha. The detection of the respective proteins correlated positively with the mRNA results. As such, these data represent the first demonstration of HBD-2 expression by astrocytes and suggest that this peptide may play a role in host defense against bacterial CNS pathogenesis.
authors.affiliation: Departments of Pediatrics and Psychiatry & Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA. hsiao-nan.hao@wayne.edu
authors.forename: H N
authors.initials: HN
authors.lastname: Hao
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: G
authors.initials: G
authors.lastname: Lotoczky
authors.forename: W E
authors.initials: WE
authors.lastname: Grever
authors.forename: W D
authors.initials: WD
authors.lastname: Lyman
mesh_terms: D000890:Anti-Infective Agents; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D016207:Cytokines / Q000494:pharmacology*; D005260:Female; D005333:Fetus; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008578:Meninges / Q000378:metabolism; D017628:Microglia / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D023083:beta-Defensins / Q000235:genetics*
chemical_list: D000890:Anti-Infective Agents; D016207:Cytokines; C406407:DEFB1 protein, human; C106641:DEFB4A protein, human; D007375:Interleukin-1; D008070:Lipopolysaccharides; D020033:Protein Isoforms; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D023083:beta-Defensins