Substance P differentially stimulates IL-8 synthesis in human corneal epithelial cells.
OBJECTIVE
To determine whether substance P (SP), a neuropeptide with proinflammatory properties, specifically interacts with human corneal epithelial cells to stimulate synthesis of the chemokines interleukin (IL)-8, monocyte chemo-attractant protein (MCP)-1, and regulated on activation normal T-cell expressed and secreted (RANTES) protein.


METHODS
Primary cultures of human corneal epithelial cells were established from human corneas. Expression of the SP receptor neurokinin (NK)-1 was determined by both the reverse transcription-polymerase chain reaction (RT-PCR) and radiolabeled saturation binding experiments. Synthesis of chemokine-specific RNA in cells stimulated with SP was analyzed by RT-PCR, and quantitation of chemokine protein synthesis was achieved by enzyme-linked immunosorbent assay.


RESULTS
Human corneal epithelial cells expressed NK-1 mRNA and bound SP with a K:(d) characteristic of NK-1. Exposure of cells to SP had no effect on IL-8-specific mRNA synthesis, whereas it increased the half-life of IL-8 transcripts by more than twofold, resulting in significant enhancement of IL-8 synthesis. The capacity of SP to bind to corneal epithelial cells and to induce IL-8 synthesis was abrogated in the presence of a specific NK-1 receptor antagonist. In contrast to IL-8, exposure of cells to SP did not stimulate synthesis of MCP-1 or RANTES.


CONCLUSIONS
The results suggest that human corneal cells express NK-1 receptors that specifically bind SP and induce IL-8 synthesis by stabilizing the chemokine's transcripts.
Tran
M T
MT
Laboratory of Experimental Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
Lausch
R N
RN
Oakes
J E
JE
D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis / Q000235:genetics; D018946:Chemokine CCL5 / Q000096:biosynthesis / Q000235:genetics; D017931:DNA Primers / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D019573:Epithelium, Corneal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D006207:Half-Life; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D064729:Neurokinin-1 Receptor Antagonists; D012333:RNA, Messenger / Q000096:biosynthesis; D018040:Receptors, Neurokinin-1 / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013373:Substance P / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D018932:Chemokine CCL2; D018946:Chemokine CCL5; D017931:DNA Primers; D016209:Interleukin-8; D064729:Neurokinin-1 Receptor Antagonists; D012333:RNA, Messenger; D018040:Receptors, Neurokinin-1; D013373:Substance P; C042867:spantide