Substance P (NK(1)) receptor expression by human colonic epithelial cell line Caco-2

The Role of Substance P Within Traumatic Brain Injury and Implications for Therapy

This review examines the role of the neuropeptide substance P within the neuroinflammation that follows traumatic brain injury. It examines it in reference to its preferential receptor, the neurokinin-1 receptor, and explores the evidence for antagonism of this receptor in traumatic brain injury with therapeutic intent. Expression of substance P increases following traumatic brain injury. Subsequent binding to the neurokinin-1 receptor results in neurogenic inflammation, a cause of deleterious secondary effects that include an increased intracranial pressure and poor clinical outcome. In several animal models of TBI, neurokinin-1 receptor antagonism has been shown to reduce brain edema and the resultant rise in intracranial pressure. A brief overview of the history of substance P is presented, alongside an exploration into the chemistry of the neuropeptide with a relevance to its functions within the central nervous system. This review summarizes the scientific and clinical rationale for substance P antagonism as a promising therapy for human TBI.

SP protects Nile tilapia (Oreochromis niloticus) against acute Streptococcus agalatiae infection

Substance P (SP) is a neuropeptide that involves in a wide variety of physiological and pathological events, mainly exerts its roles by neurokinin 1 receptor (NK1R), also modulates immune function. However, the roles of SP during immune response to acute bacterial infection of Nile tilapia (Oreochromis niloticus) remain unclear. In this study, the gene of SP precursor (tachykinin precursor 1, TAC1) and the gene of SP receptor (NK1R) from Nile tilapia were identified, and the roles of SP during an acute bacterial infection in a warm water environment were investigated. On-TAC1(Oreochromis niloticus-TAC1) contains conservative SP & NKA peptide sequences and On-NK1R contains seven conservative transmembrane domains. Their transcriptional levels were most abundant in brain and the On-TAC1 transcripts can be induced in the tilapia challenged with Streptococcus agalactiae. Furthermore, the experimental results revealed that On-SP could promote pyroptosis, suppress inflammation, and improve survival rate during acute bacterial infection. The present data lays a theoretical foundation to further elucidate the mechanism of SP protecting fish against pathogens.

Substance P failed to reverse dextran sulfate sodium-induced murine colitis mediated by mitochondrial dysfunction: implications in ulcerative colitis

As controversy exists about the efficacy of substance P (SP) in treating ulcerative colitis (UC) with no previous study highlighting the impact of SP on mitochondrial dysfunction in this diseased condition, it became logical to perform the present study. C57BL/6 J mice were administered with DSS @ 3.5%/gm body weight for 3 cycles of 5 days each followed by i.v. dose of SP @ 5nmole per kg for consecutive 7 days. Histopathological features were noticed in the affected colon along with colonic mitochondrial dysfunction, alterations in mitochondrial stress variables and enhanced colonic cell death. Interestingly, SP failed to reverse colitic features and proved ineffective in inhibiting mitochondrial dysfunction. Unexpectedly SP alone seemed to impart detrimental effects on some of the mitochondrial functions, enhanced lipid peroxidation and increased staining intensities for caspases 3 and 9 in the normal colon. To substantiate in vivo findings and to assess free radical scavenging property of SP, Caco-2 cells were exposed to DSS with or without SP in the presence and absence of specific free radical scavengers and antioxidants. Interestingly, in vitro treatment with SP failed to restore mitochondrial functions and its efficacy proved below par compared to SOD and DMSO indicating involvement of O2 •- and •OH in the progression of UC. Besides, catalase, L-NAME and MEG proved ineffective indicating non-involvement of H2O2, NO and ONOO- in UC. Thus, SP may not be a potent anti-colitogenic agent targeting colonic mitochondrial dysfunction for maintenance of colon epithelial tract as it lacks free radical scavenging property.

Interaction of neurotransmitters and neurochemicals with lymphocytes

Neurotransmitters and neurochemicals can act on lymphocytes by binding to receptors expressed by lymphocytes. This review describes lymphocyte expression of receptors for a selection of neurotransmitters and neurochemicals, the anatomical locations where lymphocytes can interact with neurotransmitters, and the effects of the neurotransmitters on lymphocyte function. Implications for health and disease are also discussed.

Neuropeptide substance P and the immune response

Substance P is a peptide mainly secreted by neurons and is involved in many biological processes, including nociception and inflammation. Animal models have provided insights into the biology of this peptide and offered compelling evidence for the importance of substance P in cell-to-cell communication by either paracrine or endocrine signaling. Substance P mediates interactions between neurons and immune cells, with nerve-derived substance P modulating immune cell proliferation rates and cytokine production. Intriguingly, some immune cells have also been found to secrete substance P, which hints at an integral role of substance P in the immune response. These communications play important functional roles in immunity including mobilization, proliferation and modulation of the activity of immune cells. This review summarizes current knowledge of substance P and its receptors, as well as its physiological and pathological roles. We focus on recent developments in the immunobiology of substance P and discuss the clinical implications of its ability to modulate the immune response.

Substance P accelerates intestinal tissue regeneration after gamma-irradiation-induced damage

Radiation therapy causes varying degrees of damage to biological systems. Many groups are investigating the mechanism underlying radiation-induced cellular damage but there are limited therapeutic solutions for affected patients. Recent studies show that substance P (SP) participates in cell proliferation. In the present study, we characterized the mechanism underlying SP-induced cellular signaling in radiation-induced damage of the intestine. Exposure of Caco-2 cells to SP increases cell proliferation and Erk phosphorylation in a time- and dose-dependent manner. The proliferation of cells exposed to gamma-irradiation is also stimulated by exposure to SP, a phenomenon that may result from inhibition of apoptosis because SP activates Akt and inhibits the cleavage of caspase-3. The effect of SP on cell proliferation and protection was confirmed by investigations in mice. Proliferating cell nuclear antigen staining shows that cell proliferation in radiation-damaged mouse intestine increases significantly upon exposure to SP. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick end labeling assay reveals fewer cells stained in SP-treated mice compared with untreated controls. These findings show the potential for SP-induced acceleration of intestinal wound healing and reveal that the mechanism underlying this process involves activation of Erk and Akt and inhibition of caspase-3 cleavage.

Substance P (SP) enhances CCL5-induced chemotaxis and intracellular signaling in human monocytes, which express the truncated neurokinin-1 receptor (NK1R)

Substance P (SP) is a potent modulator of monocyte/macrophage function. The SP-preferring receptor neurokinin-1 receptor (NK1R) has two forms: a full-length NK1R (NK1R-F) isoform and a truncated NK1R (NK1R-T) isoform, which lacks the terminal cytoplasmic 96-aa residues. The distribution of these receptor isoforms in human monocytes is not known. We previously identified an interaction among SP, NK1R, and HIV viral strains that use the chemokine receptor CCR5 as a coreceptor, suggesting crosstalk between NK1R and CCR5. The purpose of this study was to determine which form(s) of NK1R are expressed in human peripheral blood monocytes and to determine whether SP affects proinflammatory cellular responses mediated through the CCR5 receptor. Human peripheral blood monocytes were found to express NK1R-T but not NK1R-F. SP interactions with NK1R-T did not mobilize calcium (Ca2+), but SP mobilized Ca2+ when the NK1R-F was transfected into monocytes. However, the NK1R-T was functional in monocytes, as SP enhanced the CCR5 ligand CCL5-elicited Ca2+ mobilization, a response inhibited by the NK1R antagonist aprepitant. SP interactions with the NK1R-T also enhanced CCL5-mediated chemotaxis, which was ERK1/2-dependent. NK1R-T selectively activated ERK2 but increased ERK1 and ERK2 activation by CCL5. Activation of NK1R-T elicited serine phosphorylation of CCR5, indicating that crosstalk between CCL5 and SP may occur at the level of the receptor. Thus, NK1R-T is functional in human monocytes and activates select signaling pathways, and the NK1R-T-mediated enhancement of CCL5 responses does not require the NK1R terminal cytoplasmic domain.

Substance P induces intestinal wound healing via fibroblasts--evidence for a TGF-beta-dependent effect

BACKGROUND

Substance P (SP) and calcitonin gene-related peptide (CGRP) are neurotransmitters of the afferent sensory nervous system. In experimental models of colitis in rats and rabbits, a protective role of SP and CGRP on the intestinal mucosa was presumed. In part, mucosal protection depends on a SP-mediated and CGRP-mediated modulation of mucosal blood flow after injury. We thought to explore whether there is a fibroblast-mediated effect of SP and CGRP on epithelial cell restitution in vitro.

MATERIALS AND METHODS

Rat kidney fibroblast (NRK-49F) cell lines were exposed to CGRP or SP in various concentrations. After incubation, the cell culture supernatants were taken from the fibroblast cultures and were directly applied to IEC-18 or Caco-2 monolayers, which had been wounded with a razor blade 24 h before the experiments. Epithelial cell migration was assessed by counting cells across the wound edge. Epithelial cell proliferation was assessed using the 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl-tetrazolium bromide (MTT) test.

RESULTS

SP significantly induced epithelial cell migration and inhibited epithelial cell proliferation via stimulation of fibroblasts when supernatants were directly applied to epithelial cells in vitro. The effects on epithelial cell migration were abolished after neutralising anti-transforming growth factor-beta (TGF-beta) was added to the cell cultures. CGRP had no effect on epithelial cells via stimulation of fibroblasts. Neither CGRP nor SP had any effect on epithelial cell migration or proliferation when directly applied to epithelial cells.

CONCLUSION

SP modulates epithelial cell restitution in vitro mediated by fibroblasts. The epithelial cell migration depends on a TGF-beta release from SP-stimulated fibroblasts. This observation underlines an important role for the sensory nervous system in mucosal defence and repair and in keeping mucosal homeostasis. Modulation of SP may be potentially useful for the treatment of various intestinal disorders characterised by injury and ineffective repair of the intestinal mucosa.

Substance P regulates migration in rat intestinal epithelial cells

OBJECTIVE

The current study examined the effect of substance P (SP) upon intestinal epithelial cells and the mechanistic details of this interaction.

SUMMARY BACKGROUND DATA

Intestinal epithelial cells must be capable of migration to reseal mucosal wounds for several vital intestinal functions. This process is incompletely understood; however, recent evidence implicates the neurotransmitter SP in this process.

METHODS

Normal rat intestinal epithelial cells (IEC-6 cells) were studied to identify the presence of the SP receptor (NK-1 subtype) and then exposed to physiologic doses of SP and antagonists to assess for increased migration.

RESULTS

Examination IEC-6 cells revealed the presence of the SP receptor. Wounding of these cells followed by subsequent exposure to SP (10 mol/L) resulted in increased migration. Similarly, SP-induced increases in intracellular calcium concentration and actomyosin stress fiber formation. These effects were all blocked through specific NK-1 receptor antagonists.

CONCLUSIONS

These results indicate that SP stimulates intestinal epithelial migration and increases in calcium concentration. These data support a beneficial role for SP in the maintenance of intestinal mucosal homeostasis.

Substance P receptor expression in human skin keratinocytes and fibroblasts

BACKGROUND

There is increasing evidence that neuropeptides, especially substance P (SP), may be involved in the pathogenesis of cutaneous allergic inflammation (CAI).

OBJECTIVES

To investigate expression of the SP receptor (neurokinin-1 receptor, NK-1R) in human epidermal keratinocytes and dermal fibroblasts and its potential influence in CAI.

METHODS

HaCaT cells (a human epidermal keratinocyte cell line) and dermal fibroblasts were cultured. The expression of NK-1R protein was examined by immunohistochemistry, and the mRNA level was detected by semiquantitative reverse transcriptase-polymerase chain reaction. The modulation of NK-1R expression in HaCaT cells and fibroblasts was detected by flow cytometry and Western blotting analysis.

RESULTS

NK-1R expression was found in HaCaT cells and fibroblasts. The expression of NK-1R mRNA in fibroblasts was weaker than in HaCaT cells. SP and interferon (IFN)-gamma significantly upregulated the expression of NK-1R. [d-Arg(1), d-Trp(7,9) Leu(11)]-SP (Spantide I), a panspecific NK-1R antagonist, reduced the expression of NK-1R stimulated by SP.

CONCLUSIONS

HaCaT cells and fibroblasts can express NK-1R at protein and transcription levels, and the expression was modulated by SP, IFN-gamma and Spantide I. This indicates that keratinocytes and fibroblasts are involved in the regulation of skin immunity and that NK-1R may play an important role in the pathogenesis of CAI.

Coexpression of preprotachykinin A and B transcripts in the bovine corpus luteum and evidence for functional neurokinin receptor activity in luteal endothelial cells and ovarian macrophages

Nonneuronal cell sources of tachykinins, such as substance P (SP) and neurokinin B (NKB), have been demonstrated in leukocytes, endothelial cells and endocrine cells, and may play a role in corpus luteum (CL) development. For this reason, we analyzed mRNA presence for the two tachykinin precursors together with the neurokinin-1 receptor and the neurokinin-3 receptor (NK-1R and NK-3R, preferred by SP and NKB, respectively) in bovine CL at various stages in the luteal phase. Using the RT-PCR technique, we detected coexpression for the preprotachykinin A gene (PPT-A), which encodes SP and neurokinin A (NKA), and the preprotachykinin B gene (PPT-B) for NKB in the CL at the development, secretion and regression stages. Coexpression was also noted for NK-1R and NK-3R gene transcripts. Cultures of endothelial cells (ECs) derived from bovine CL expressed NK-1R and NK-3R mRNA, as did ovarian macrophages. Agonist treatment induced a stronger intracellular calcium ([Ca2+]i) increase after activation of NK-1R compared to NK-3R, a result that we verified by calcium imaging. This is the first evidence for functional tachykinin receptor activity in luteal ECs and ovarian macrophages from bovine CL.

Substance P and the neurokinin-1 receptor in relation to eosinophilia in ulcerative colitis

Substance P (SP) has been implicated in the pathophysiology of ulcerative colitis (UC) and it has been suggested that blocking of its effect would be advantageous in this disease. Eosinophils have also been implicated in the pathophysiology of UC. In the present study, specimens from the sigmoid colon of UC patients were investigated by the use of antisera against SP and the neurokinin-1 receptor (NK-1R) and staining for demonstration of eosinophils. The degrees of SP innervation and NK-1R immunoreaction, as well as the levels of eosinophil infiltration, varied between different patients. Interestingly, NK-1R immunoreaction in the epithelium was often seen to be the most marked where there were numerous eosinophils in the underlying mucosa and where the mucosa showed a marked morphologic derangement. The observations suggest that there are marked fluctuations in effects of SP and eosinophils during the disease. The infiltrating eosinophils may be involved in the destruction of the mucosal tissue. Furthermore, for the majority of cases where there is marked derangement of the mucosa, it is apparent that there is an upregulation of the NK-1 receptor in the epithelium in parallel with the infiltration of the eosinophils.

Effects of peptides, with emphasis on feeding, pain, and behavior A 5-year (1999-2003) review of publications in Peptides

Novel effects of naturally occurring peptides are continuing to be discovered, and their mechanisms of actions as well as interactions with other substances, organs, and systems have been elucidated. Synthetic analogs may have actions similar or antagonistic to the endogenous peptides, and both the native peptides and analogs have potential as drugs or drug targets. The journal Peptides publishes many leading articles on the structure-activity relationship of peptides as well as outstanding reviews on some families of peptides. Complementary to the reviews, here we extract information from the original papers published during the past five years in Peptides (1999-2003) to summarize the effects of different classes of peptides, their modulation by other chemicals and various pathophysiological states, and the mechanisms by which the effects are exerted. Special attention is given to peptides related to feeding, pain, and other behaviors. By presenting in condensed form the effects of peptides which are essential for systems biology, we hope that this summary of existing knowledge will encourage additional novel research to be presented in Peptides.