Enkephalins as immunomodulators

Plotnikoff, Nicholas P.; Miller, Gary M.

doi:10.1016/0192-0561(83)90020-6

Cited by 165 publications

(23 citation statements)

References 10 publications

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“…In adult thymocytes and T lymphocytes clones, PEA mRNA is not expressed constitutively, but is detected following cell activation. After exogenous administration, enkephalins affect several immunologic functions, including antibody production (12), NK cell activity against tumors and viral infections (13), macrophage and polymorphonuclear leukocyte functions (14,15), graft rejections (16), and mitogenstimulated lymphocyte proliferation (17). Recently, it was shown that very low concentrations of PEA and Met-enkephalin differentially affect IgM and IgG production by B cells (18).…”

mentioning

confidence: 99%

Characterization of Antibacterial COOH-terminal Proenkephalin-A-derived Peptides (PEAP) in Infectious Fluids

Goumon¹,

Lugardon²,

Kieffer³

et al. 1998

Journal of Biological Chemistry

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mentioning

confidence: 99%

Characterization of Antibacterial COOH-terminal Proenkephalin-A-derived Peptides (PEAP) in Infectious Fluids

Goumon¹,

Lugardon²,

Kieffer³

et al. 1998

Journal of Biological Chemistry

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“…Met-enkephalin has been shown to enhance human T lymphocyte proliferation in vitro induced by phytohemagglutinin, purified protein derivative and candida antigen [3,12,44]. In an earlier report, we have also shown that Met-enkephalin as well as analogs (1) and (2) stimulate T cell proliferation on the 5th day.…”

Section: Peptide Concentrationmentioning

confidence: 72%

“…Although their precise physiological significance still remains elusive, the enkephalins have been reported to exhibit analgesic, antidepressant, antianxiety and anticonvulsant activities [2]. Furthermore, enkephalins have also been found to act as immunomodulators [3][4][5][6][7][8][9][10][11][12]. Methionine-enkephalin (Met-enkephalin; Tyr-Gly-GlyPhe-Met) is produced by the cells of the neuroendocrine and immune systems which are capable of processing the pentapeptide from its precursor protein and bear its receptors on their surface.…”

Section: Introductionmentioning

confidence: 99%

δ-Opioid Receptor Antagonist Inhibits Immunomodulation by Met-Enkephalin Analogs

Singh¹,

Bajpai²,

Narayan³

et al. 1999

Neuroimmunomodulation

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The methionine-enkephalin (Met-enkephalin, Tyr-Gly- Gly-Phe-Met) analogs Tyr-D-Ala-Gly-MePhe-Met NHC₃H₇- iso (1) and Tyr-D-Ala-Gly-MePhe-Gly-NHC₃H₇-iso (2) have been shown to enhance human T cell proliferation in in vitro treatment. Their immunomodulatory activities were completely blocked by naloxone, an opioid antagonist. Now we demonstrate that a selective δ-opioid receptor antagonist, ICI-174,864, completely blocks enhancement of T cell proliferation by analogs (1) and (2). The T cell-stimulatory effect was only partially inhibited by the µ-receptor-selective antagonist, β-funaltrexamine hydrochloride. The κ-opioid receptor antagonist, nor-binaltorphimine dihydrochloride, showed no effect on T cell-proliferation stimulated by analogs (1) and (2). These observations suggest that analogs (1) and (2) of Met-enkephalin stimulate T cell proliferation predominantly via δ-opioid receptor present on T cells.

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“…The existence of neuroimmune interactions was recognized in the early 1980s [14]; the role attributed to neuropeptides is that of modulating, rather than eliciting, immune effects [15,16]. Neuroimmune interactions are bidirectional, and the opioid peptides present in plasma, as well as by the adrenal medulla chromaffin cells, are released by immunocompetent cells [17].…”

Section: Introductionmentioning

confidence: 99%

Age Increases Leucine Enkephalin Hydrolysis in Human Plasma

Bongiorno

Marzano²,

Marini³

et al. 1998

Gerontology

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Background: The existence of age-associated alterations in immune functions and neuropeptides capable of modulating these functions prompted us to advance the hypothesis that the degradation of plasma neuropeptides, specifically opioid peptides, may be altered by aging. Objective: To verify the possible existence of age-induced variations in neuropeptide hydrolysis in human plasma, using leucine enkephalin as the model substrate. Methods: The hydrolysis of leucine enkephalin and the formation of its hydrolysis byproducts in the presence of plasma enzymes were studied by kinetic and chromatographic techniques in a group of elderly individuals and a control group. Results: The results obtained indicate that in elderly individuals the activity of enkephalin-degrading plasma enzymes is greater than in controls. ANOVA analysis of these data indicates that the dependency of the variation of hydrolysis upon the 2 age groups is statistically significant. Increased substrate hydrolysis, and a modified hydrolysis pattern, appear to be associated with increased activity of the enzymes involved, and with different distribution of the individual enzymes within each class, as well as with severely reduced activity of the low molecular weight plasma inhibitors. Conclusion: The combination of the above-mentioned factors appears to define a characteristic hydrolysis pattern for elderly individuals which is different from that found in controls.

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Enkephalins as immunomodulators

Cited by 165 publications

References 10 publications

Characterization of Antibacterial COOH-terminal Proenkephalin-A-derived Peptides (PEAP) in Infectious Fluids

Characterization of Antibacterial COOH-terminal Proenkephalin-A-derived Peptides (PEAP) in Infectious Fluids

δ-Opioid Receptor Antagonist Inhibits Immunomodulation by Met-Enkephalin Analogs

Age Increases Leucine Enkephalin Hydrolysis in Human Plasma

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