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Human monocytes and macrophages express substance P and neurokinin-1 receptor
1Division of Immunologic and Infectious Diseases, Joseph Stokes Jr. Research Institute at the Children's Hospital of Philadelphia, PA 19104, USA.
Abstract:
We present data demonstrating the gene expression of substance P and its receptor in human peripheral blood-isolated monocytes and macrophages. Using the RT-PCR assay, preprotachykinin-A (substance P) mRNA is detected in human peripheral blood-isolated monocytes and macrophages. Among the alpha, beta, and gamma transcripts of the substance P gene, only the beta and gamma transcripts are detectable in these cells. By Southern blot assay these RT-PCR-amplified transcripts are recognized using a specific substance P probe. Sequence analysis of the RT-PCR products from both monocytes and macrophages also confirmed the structure of these transcripts, which are identical to those found in human neuronal cells. At the protein level, both human monocytes and macrophages produced endogenous substance P as determined by an enzyme immunoassay. Capsaicin, a vanillyl fatty acid amide (ingredient of hot pepper), released substance P from both human monocytes and macrophages. In addition, using nested RT-PCR analysis, we identified the presence of mRNA for neurokinin-1 receptor (the receptor for substance P) in human peripheral blood-isolated monocytes and macrophages, which was confirmed by DNA sequencing analysis. The demonstration that human monocytes and macrophages express substance P and its receptor support the notion that substance P is biologically involved in regulating the functions of these cells in an autocrine fashion.
Insights
Human monocytes and macrophages express substance P and its receptor, suggesting substance P regulates these immune cells. This study identifies key components of the tachykinin system in immune cells.
Area of Science:
- Immunology
- Neuroscience
- Molecular Biology
Background:
- Substance P is a neuropeptide primarily known for its role in pain and inflammation.
- Its presence and function in immune cells, particularly monocytes and macrophages, are not fully elucidated.
Purpose of the Study:
- To investigate the gene and protein expression of substance P and its receptor in human peripheral blood-isolated monocytes and macrophages.
- To explore the potential autocrine regulation of these immune cells by substance P.
Main Methods:
- Reverse Transcription Polymerase Chain Reaction (RT-PCR) to detect mRNA transcripts.
- Southern blot assay for transcript identification.
- Enzyme immunoassay (EIA) for protein quantification.
- DNA sequencing for transcript structure confirmation.
- Nested RT-PCR for neurokinin-1 receptor mRNA detection.
Main Results:
- Substance P (preprotachykinin-A) mRNA, specifically beta and gamma transcripts, was detected in human monocytes and macrophages.
- Sequence analysis confirmed these transcripts are identical to those in neuronal cells.
- Both cell types produced endogenous substance P protein.
- Capsaicin stimulated substance P release from monocytes and macrophages.
- mRNA for the neurokinin-1 receptor (NK1R) was identified in these cells.
Conclusions:
- Human monocytes and macrophages express both substance P and its cognate receptor, neurokinin-1.
- These findings support a role for substance P in the autocrine regulation of monocyte and macrophage functions.
- This highlights a potential link between the nervous and immune systems through the tachykinin pathway.