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Induction of human β‐defensin‐2 expression in human astrocytes by lipopolysaccharide and cytokines
Author(s) -
Hao HsiaoNan,
Zhao Jiun,
Lotoczky Gregory,
Grever William E.,
Lyman William D.
Publication year - 2001
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2001.00305.x
Subject(s) - biology , astrocyte , defensin , microbiology and biotechnology , gene isoform , beta defensin , tumor necrosis factor alpha , lipopolysaccharide , immunocytochemistry , cell culture , immunology , gene , central nervous system , biochemistry , endocrinology , genetics
Defensins are cationic peptides with broad‐spectrum antimicrobial activity. They are members of a supergene family consisting of α and β subtypes and each subtype is comprised of a number of different isoforms. For example, human α‐defensin (HAD) has six isoforms, which are expressed by polymorphonuclear leukocytes and Paneth cells. In contrast, human β‐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 μg/mL, interleukin‐1 beta (IL‐1β) at 1–50 ng/mL, or tumor necrosis factor alpha (TNF‐α) 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‐1β or TNF‐α. 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.