Influence of opioid peptides on human neutrophil apoptosis and activation in vitro

Beta-endorphin inhibits the inflammatory response of bovine endometrial cells through δ opioid receptor in vitro

Postpartum uterine infections are common reproductive diseases in postpartum cows. Evidence has shown that plasma β-endorphins increase during bovine uterine inflammation. However, the effect of β-endorphins on the inflammatory response in bovine endometrium has not been clarified. The aim of this study was to investigate the effect of β-endorphins on the inflammatory response of bovine endometrial epithelial and stromal cells, and to explore the possible mechanism. The cells were treated with E. coli lipopolysaccharide (LPS) to simulate inflammation, which was characterized by the significant activation of NF-κB signaling pathway and the increased gene expression of the downstream proinflammatory cytokines (approximately 1.2- to 15-fold increase, P < 0.05). By using Western blot and qPCR techniques, we found that β-endorphins inhibited the key protein expression of NF-κB pathway, and the gene expressions of TNF, IL1B, IL6, CXCL8, nitric oxide synthase 2, and prostaglandin-endoperoxide synthase 2 (P < 0.05). The co-treatment of β-endorphins and opioid antagonists showed that the anti-inflammatory effect of β-endorphins could be blocked (P < 0.05) by non-selective opioid antagonist naloxone or δ opioid receptor antagonist ICI 154129, but not the μ opioid receptor antagonist CTAP (P > 0.05). In conclusion, β-endorphins may inhibit the inflammatory response of bovine endometrial epithelial and stromal cells through δ opioid receptor.

Hormones in the immune system and their possible role. A critical review

Immune cells synthesize, store and secrete hormones, which are identical with the hormones of the endocrine glands. These are: the POMC hormones (ACTH, endorphin), the thyroid system hormones (TRH, TSH, T3), growth hormone (GH), prolactin, melatonin, histamine, serotonin, catecholamines, GnRH, LHRH, hCG, renin, VIP, ANG II. This means that the immune cells contain all of the hormones, which were searched at all and they also have receptors for these hormones. From this point of view the immune cells are similar to the unicells (Tetrahymena), so it can be supposed that these cells retained the properties characteristic at a low level of phylogeny while other cells during the evolution accumulated to form endocrine glands. In contrast to the glandular endocrine cells, immune cells are polyproducers and polyreceivers. As they are mobile cells, they are able to transport the stored hormone to different places (packed transport) or attracted by local factors, accumulate in the neighborhood of the target, synthesizing and secreting hormones locally. This is taking place, e.g. in the case of endorphin, where the accumulating immune cells calms pain caused by the inflammation. The targeted packed transport is more economical than the hormone-pouring to the blood circulation of glandular endocrines and the targeting also cares the other receptor-bearing cells timely not needed the effect. Mostly the immune-effects of immune-cell derived hormones were studied (except endorphin), however, it is not exactly cleared, while the system could have scarcely studied important roles in other cases. The evolutionary aspects and the known as well, as possible roles of immune-endocrine system and their hormones are listed and discussed.

Effects of opioids on phagocytic function, oxidative burst capacity, cytokine production and apoptosis in canine leukocytes

Opioids alter immune and apoptotic pathways in several species. They are commonly used in companion animals affected with infectious and/or inflammatory disease, but the immunomodulatory and apoptotic effects of these drugs in dogs are relatively unknown. The aim of the present study was to evaluate the effects of morphine, buprenorphine and fentanyl on canine phagocyte function, oxidative burst capacity, leukocyte cytokine production, and lymphocyte apoptosis. Blood from six healthy adult dogs was incubated in the presence or absence of morphine (200 ng/mL), buprenorphine (10 ng/mL) or fentanyl (10 ng/mL) for 3 h (phagocytic function; cytokine production) or 8 h (apoptosis). Neutrophil phagocytosis of opsonized Escherichia coli, respiratory burst capacity after stimulation with opsonized E. coli or phorbol 12-myristate 13-acetate (PMA), and Annexin V-FITC staining of apoptotic lymphocytes were evaluated using flow cytometry. Leukocyte production of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-10 was assessed after incubation with lipopolysaccharide (LPS), lipoteichoic acid (LTA) or peptidoglycan. Morphine promoted a more intense respiratory burst. Morphine, buprenorphine and fentanyl all promoted LPS- or LTA-induced TNF-α and IL-10 production. However, the opioids tested did not alter TNF-α:IL-10 ratios. Morphine, buprenorphine and fentanyl all inhibited neutrophil apoptosis, an effect that was not concentration dependent in nature. These data indicate that opioids alter immune and apoptotic pathways in dogs. The possible effects of opioids on immune and cellular responses should be considered when designing studies and interpreting outcomes of studies involving administration of opioids in dogs.

Induction on differentiation and modulation of bone marrow progenitor of dendritic cell by methionine enkephalin (MENK)

Methionine enkephalin (MENK), the endogenous neuropeptide, is known to exert direct effects on the neuroendocrine and the immune systems and participates in regulation of various functions of cells related to both the innate and adaptive immune systems. Dendritic cells (DCs) play important role in initiating and regulating T cell responses. The aim of this work is to investigate the effects of MENK on differentiation, maturation, and function of DCs derived from murine bone marrow progenitors (BM-derived DCs). Our result showed that MENK could induce BM-derived DCs to polarize predominantly to mDC subtype, rather than pDC both in vivo and in vitro, and this was in favor of Th1 response. BM-derived DCs, after treatment with MENK, up-regulated the expressions of MHC class II and key costimulatory molecules. Result by RT-PCR showed MENK could increase expressions of delta and kappa receptors on BM-derived DCs. Also MENK promoted BM-derived DCs to secret higher levels of proinflammatory cytokines of IL-12p70, TNF-α. Furthermore, differentiated BM-derived DCs treated with MENK displayed higher activity to induce allogeneic T cell proliferation and MENK also inhibited tumor growth in vivo and induced apoptosis of tumor cells in vitro. Thus, it is concluded that MENK could be an effective inducer of BM-derived DCs and might be a new therapeutic agent for cancer, as well as other immune handicapped disease. Also we may consider MENK as a potential adjuvant in vaccine preparation.

Comparison of stimulating effect on subpopulations of lymphocytes in human peripheral blood by methionine enkephalin with IL-2 and IFN-γ

The aim of this study was to investigate the effects of mechanisms of methionine enkephalin (MENK) on lymphocytes in human peripheral blood. We detected CD4+T cells, CD8+T cells, CD4+CD25+ regulatory T cells (Treg), dendritic cells (DCs), natural killer cells (NK), NKT cells and γδT cells before and after treatment with 10 (-12) M MENK, in cell culture by FCM and RT-PCR. Our findings show that MENK stimulating expansion of lymphocyte subpopulationns by inhibiting CD4+CD25+ regulatory T cells (Treg), which is unique discovery of our study. We may use MENK as a drug to treat cancer patients, whose immune systems are damaged by chemotherapy or radiotherapy.

Endogenous opioid peptides in regulation of innate immunity cell functions

Endogenous opioid peptides comprise a group of bioregulatory factors involved in regulation of functional activity of various physiological systems of an organism. One of most important functions of endogenous opioids is their involvement in the interaction between cells of the nervous and immune systems. Summary data on the effects of opioid peptides on regulation of functions of innate immunity cells are presented.

Accelerated apoptosis of blood leukocytes and oxidative stress in blood of patients with major depression

Acceleration of blood leukocyte apoptosis in major depression has been described. The present studies have been undertaken to estimate the level of apoptosis of blood leukocytes in patients with depression and to examine the mechanisms leading to apoptosis. Blood was taken from 29 patients with depression (age 48.2+/-11.2, 14 males, 15 females) and 30 healthy controls (age 41.3+/-4.1, 15 males, 15 females), and apoptosis was estimated by the cytometric method by measurements of annexin V binding, mitochondrial membrane potential (DeltaPsi), bcl-2, bax, and Fas (CD95) expression in CD4+, CD8+ and CD14+ cells. The amounts of cytochrome c released from mitochondria to cytosol of peripheral blood mononuclear cells (PBMCs) and polymorphonuclear cells (PMNs) were also measured. The levels of reactive oxygen species (ROS) released from PMNs were examined as was the serum activity of superoxide dismutase (SOD), catalase (CAT), and total peroxidase (PER). Additionally, serum levels of the tumor necrosis factor (TNF-alpha) and interleukin-6 (IL-6) were estimated. Our experiments indicated accelerated apoptosis of CD4+ T lymphocytes and CD14+ cells (mainly neutrophils) of depressed patients as well as a significant increase in the percent of Fas-expressing cells. Bcl-2 and bax expression was higher in cells of depressed patients than in control, however, bcl-2/bax ratio was significantly decreased in CD14+ cells of depressed patients. PMNs isolated from the blood of the patients produced more ROS spontaneously and after induction with phorbol ester (PMA) than PMNs of the healthy control. A significant increase in serum activity of SOD, CAT and PER was also detected. Overproduction of superoxide anion correlated positively with the level of PMNs apoptosis (measured by cytochrome c release), suggesting that superoxide anion might be an important factor inducing apoptotic death of blood cells. The result of our experiment indicated that apoptosis of immune cells may affect patient's susceptibility to different infections and application of antioxidants in medication of patients with depression will be beneficial for them. The increased level of IL-6 in sera of the depressed patients did not correlate with overproduction of ROS, suggesting that this cytokine is not involved in oxidative stress and apoptosis of leukocytes.

Beta-endorphin differentially affects inflammation in two inbred rat strains

It has been shown that inflammation of rat paws elicits accumulation of opioid peptide beta-endorphin-containing immune cells in the inflamed subcutaneous tissue, contributing to immunocyte-produced pain suppression. However, the possible mechanisms involved in the pharmacological application of beta-endorphin in rat paw inflammation have not been investigated. The present study was set up to explore the effects of intraplantar injection of beta-endorphin on Concanavalin A-induced paw edema in two inbred rat strains, Albino Oxford (AO) and Dark Agouti (DA). Both high dose-induced suppression and low dose-induced potentiation of edema development in AO and DA rats, respectively, were blocked with antagonists specific for delta (naltrindole) and kappa (nor-binaltorphimine) opioid receptors. beta-endorphin in vitro decreased phagocytosis and increased nitric oxide (NO) production in air pouch granulocytes obtained from AO rats. However, in cells from DA rat strain beta-endorphin modulated both phagocytosis and NO production in a concentration-dependent manner. It could be concluded that the strain-dependent opposing effects of beta-endorphin on paw inflammation are mediated through delta and kappa opioid receptors and probably involve changes in the production of reactive oxygen species by inflammatory cells. Our results point to the importance of genotype for pharmacological manipulations and the development of inflammation.

Flow cytometric evaluation of human neutrophil apoptosis during nitric oxide generation in vitro: the role of exogenous antioxidants

Among numerous inflammatory mediators a nitric oxide molecule is supposed to be important in the modulation of neutrophil survival in vivo and in vitro. The effect of exogenous supply of NO donors such as SNP, SIN-1, and GEA-3162 on the course of human neutrophil apoptosis and the role of extracellular antioxidants in this process was investigated. Isolated from peripheral blood, neutrophils were cultured in the presence or absence of NO donor compounds and antioxidants for 8, 12, and 20 hours. Apoptosis of neutrophils was determined in vitro by flow cytometric analysis of cellular DNA content and Annexin V protein binding to the cell surface. Exposure of human neutrophils to GEA-3162 and SIN-1 significantly accelerates and enhances their apoptosis in vitro in a time-dependent fashion. In the presence of SNP, intensification of apoptosis has not been revealed until 12 hours after the culture. The inhibition of GEA-3162- and SIN-1-mediated neutrophil apoptosis by superoxide dismutase (SOD) but not by catalase (CAT) was observed. Our results show that SOD and CAT can protect neutrophils against NO-donors-induced apoptosis and suggest that the interaction of NO and oxygen metabolites signals may determine the destructive or protective role of NO donor compounds during apoptotic neutrophil death.