Tumor necrosis factor (TNF) -alpha induces pleiotropic cellular effects through a 55kDa, type 1 receptor (TNFR1) and a 75kDa type 2 receptor (TNFR2). Moreover, it participates in the pathogenesis of several CNS diseases, including demyelinating diseases. TNF- receptors are differentially expressed and are regulated in many cell types. However, data regarding the TNF-alpha receptor expression and regulation in human astrocytes is limited to date. We investigated TNF-alpha receptor expression, its regulation by cytokines, and its functional role in primary cultured human fetal astrocytes, which are the most abundant cellular population in the central nervous system and are known to be immunologically active. In this study, astrocytes were found to constitutively and predominantly transcribe, translate and shed TNFR1 rather than TNFR2, but TNFR2 expression was increased by adding TNF-alpha, IL-1, and IFN-gamma, but not by adding LPS. To determine the functional roles of TNFR1 and TNFR2 on TNF induction, we investigated NF-kappaB activation and TNF-alpha induction after neutralizing TNFR1 and TNFR2 by an antibody treatment. We found that NF-kappaB activation and TNF-alpha induction are blocked by TNFR1 neutralizing antibody treatments.
Receptors, Tumor Necrosis Factor, Type II/genetics/*metabolism/physiology ; Receptors, Tumor Necrosis Factor, Type I/genetics/*metabolism/physiology ; RNA, Messenger/metabolism ; NF-kappa B/metabolism ; Humans ; Gene Expression Regulation ; Fetus/cytology ; Cytokines/*pharmacology ; Cells, Cultured ; Astrocytes/drug effects/*metabolism