Lipopolysaccharide-induced upregulation of tumor necrosis factor-alpha (TNF-alpha) and TNF receptors in rat sciatic nerve.
The proinflammatory and lipopolysaccharide (LPS)-inducible cytokine tumor necrosis factor alpha (TNF-alpha) has been shown to enhance primary sensory nociceptive signaling. However, the precise cellular sites of TNF-alpha and TNF receptors synthesis are still a matter of controversy. Therefore, we focused our study on TNF-alpha, TNFR1, and TNFR2 protein synthesis and expression patterns in sciatic nerve of controls and rats under systemic challenge with LPS. The enzyme-linked immunosorbent (ELISA) assay showed that the protein level of TNF-alpha reached peak at 6 h. Double immunofluorescence revealed that LPS-induced expression of TNF-alpha exclusively located in a subpopulation of Schwann cells, endothelial cells, and macrophages, which increased at late time point in the rat sciatic nerve. Positive staining of TNF receptors were also found in Schwann cells and a few endothelial cells. These observations have demonstrated the production of this proinflammatory cytokine by peripheral nerve glia especially Schwann cells. Synthesized TNF-alpha might directly act on peripheral nerve glia via TNF receptors, but the inherent mechanisms remain unknown. Further studies are needed to confirm the pathogenic role of tumor necrosis factor in the early stage of inflammation.
Wang
Youhua
Y
The Jiangsu Province Key Lab of Neuroregeneration, Nantong University, Nantong, 226001, People's Republic of China.
Zhou
Dan
D
Shen
Qin
Q
Cheng
Chun
C
Liu
Hai-ou
HO
Qin
Yongwei
Y
Sun
Linlin
L
Xiao
Feng
F
Zhao
Jian
J
Shen
Aiguo
A
D000818:Animals; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000187:drug effects / Q000235:genetics*; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000187:drug effects / Q000235:genetics*; D012584:Sciatic Nerve / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
D008070:Lipopolysaccharides; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; C506237:Tnfrsf1a protein, rat; D014409:Tumor Necrosis Factor-alpha