NF-kappaB, nitric oxide and opiate signaling

Discovery of an effective anti-inflammatory agent for inhibiting the activation of NF-κB

In this study, based on the effect of compounds on the activation of NF-κB and NO release, compound 51 was discovered as the best one with NO release inhibition IC₅₀ value was 3.1 ± 1.1 μM and NF-κB activity inhibition IC₅₀ value was 172.2 ± 11.4 nM. Compound 51 could inhibit the activation of NF-κB through suppressing phosphorylation and nuclear translocation of NF-κB, and suppress LPS-induced inflammatory response in RAW264.7 cells, such as the over-expression of TNF-α and IL-6, which were target genes of NF-κB. This compound also showed preferable anti-inflammatory activity in vivo, including alleviating significantly gastric distention and splenomegaly caused by LPS stimulation, reducing the level of oxidative stress induced by LPS, and inhibiting the expression of IL-6 and TNF-α in serum. Thus, it's reasonable to consider that this compound is a promising small molecule with anti-inflammatory effect for inhibiting the NF-κB signalling pathway.

Genes regulating oxidative-inflammatory response in circulating monocytes and neutrophils in septic syndrome

Despite significant progress in the past decades, sepsis still lacks a specific treatment. Under normal conditions, leucocytes play a critical role in controlling infection and it is suggested that their activity is impaired during sepsis which contribute to the dysregulation of immune reactions. Indeed, in response to infection, several intracellular pathways are affected mainly those regulating the oxidative- inflammatory axis. Herein, we focused on the contribution of NF-kB, iNOS, Nrf2, HO-1 and MPO genes in the pathophysiology of septic syndrome, by analyzing the differential expression of their transcripts in circulating monocytes and neutrophils, and monitoring the nitrosative/oxidative status in septic syndrome patients. Circulating neutrophils of septic patients displayed a significant overexpression of NF-kB compared to other groups. In monocytes, patients with septic shock expressed the highest levels of iNOS and NF-kB mRNA. However, genes involved in cytoprotective response had increased expression in patients with sepsis, in particular, the Nrf2 and its target gene HO-1. Moreover, patient monitoring indicates that the iNOS enzyme expression and NO plasma levels may play a role in assessing the severity of septic conditions. Overall, in either monocytes or neutrophils, we pointed out the major role of NF-κB and Nrf2 in the pathophysiological process. Therefore, therapies targeted to redox abnormalities may be useful for better management of septic patients.

Anti-psoriatic and anti-inflammatory effects of Kaempferia parviflora in keratinocytes and macrophage cells

Kaempferia parviflora (KP) has been used as folk medicine for curing various conditions, including anti-inflammatory diseases. However, anti-psoriatic effects in an aspect of suppression of NF-κB activation have not been explored. Therefore, our current study aimed to elucidate the anti-inflammation of KP in lipopolysaccharide (LPS)-induced RAW264.7 cells and anti-psoriatic effects of KP in cytokine-induced human keratinocytes, HaCaT cells. We discovered that KP extract significantly suppressed LPS-induced inflammation at both gene expression and protein production. Specifically, dramatic reduction of nitric oxide (NO) was explored by using Griess method. Consistently, data from RT-qPCR, ELISA, and western blot analysis confirmed that crucial inflammatory and psoriatic markers including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6, IL-17, IL-22, and IL-23 were significantly decreased by the action of KP. These events were associated with the results from immunofluorescence study and western blot analysis where the activation of NF-κB upon LPS stimulation was clearly inhibited by KP through its ability to suppress IκB-α degradation resulting in inhibition of NF-κB nuclear translocation. Furthermore, KP extract significantly inhibited LPS-stimulated phosphorylation of ERK1/2, JNK, and p38 in a dose-dependent manner, along with inhibition of ERK1/2 activation in both TNF-α- and EGF-induced HaCaT cells. Interestingly, HaCaT cells exposed to 15 μg/mL of KP also exhibited significant decrease of cell migration and proliferation. Our results revealed that KP extract has a potential to be developed as a promising agent for treating inflammation and psoriasis, in part through targeting the proliferation and the NF-κB pathways.

Opioids and matrix metalloproteinases: the influence of morphine on MMP-9 production and cancer progression

Opioids are widely administered to alleviate pain, including chronic pain in advanced cancer patients. Among opioids, morphine is one of the most clinically effective drugs for the palliative management of severe pain. In the last few decades, there has been a debate around the possible influence of opioids such as morphine on tumour growth and metastasis. Whilst several in vitro and in vivo studies suggest the possible modulatory effects of morphine on tumour cells, little is known about the impact of this analgesic drug on other mediators such as matrix metalloproteinases (MMPs) that play a key role in the control of cancer cell invasion and metastasis. MMP-9 has been considered as one of the principal mediators in regulation of not only the initial steps of cancer but during the invasion and spreading of cancer cells to distant organs. Herein, current studies regarding the direct and indirect effects of morphine on regulation of MMP-9 production are discussed. In addition, drawing from previous in vivo and in vitro studies on morphine action in regulating MMP-9 production, the potential roles of several underlying factors are summarised, including nuclear factor kappa-B and intracellular molecules such as nitric oxide.

Chromosomal Processes in Mind-Body Medicine: Chronic Stress, Cell Aging, and Telomere Length

Stress affects cellular aging and inflammatory and chromosomal processes, including telomere length, thereby potentially compromising health and facilitating disease onset and progression. Stress-related diseases and strategies to manage stress usually require integrative or behavioral therapeutic approaches that also operate on cellular levels. Mind-body medicine (MBM) uses the interaction between the mind, body, behavior, and the environment to correct physical and psychological malfunctions, thus ameliorating disease states and improving health. The relaxation response (RR) is a physiological opponent of stress and the stress response (SR) (i.e., fight-or-flight response), also invoking molecular anti-stress processes. Techniques that elicit the RR are at the core of practically all MBM interventions. We surmise that these techniques can also affect chromosomal and telomere processes, molecular aging, and the modulation of inflammatory states on cellular levels.

Fentanyl inhibits the progression of human gastric carcinoma MGC-803 cells by modulating NF-κB-dependent gene expression in vivo

Fentanyl is widely used to treat acute and chronic pain. Previous in vitro studies by the present authors demonstrated that fentanyl inhibits the progression of the MGC-803 human gastric carcinoma cell line by affecting apoptosis-related genes, including nuclear factor-kappa B (NF-κB) and phosphatase and tensin homolog. In the present study, the effects of fentanyl on NF-κB-dependent gene expression were investigated in vivo. Nude mice were inoculated with an MGC-803 cell suspension, and mice that developed subcutaneous tumors measuring >1.0×1.0 cm were selected for study. Mice were administered intraperitoneal injections of fentanyl (0.05 mg/kg, group F1; 0.1 mg/kg, group F2; 0.2 mg/kg, group F3; and 0.4 mg/kg, group F4) for 14 consecutive days. Non-fentanyl-treated mice (group C) and normal saline-treated mice (group N) served as the control groups. Tumor growth was monitored by calculating the time-shift of the growth curve. Morphological changes were also observed using microscopy. The expression of NF-κB, B-cell lymphoma-2 (Bcl-2), B-cell associated X protein (Bax), vascular endothelial growth factor-A (VEGF-A) and matrix metalloproteinase-9 (MMP-9) in the subcutaneous tumor tissue was also analyzed by reverse transcription-polymerase chain reaction and western blot analysis, and confirmed using immunohistochemistry. The relative tumor volumes of groups F1, F2, F3 and F4 were significantly reduced compared with groups C and N. Furthermore, subcutaneous tumor cells exhibited nuclear swelling, chromatin condensation, reduced chromatin and nuclear fragmentation in the F1, F2, F3 and F4 groups. The number of NF-κB⁺, Bcl-2⁺, VEGF-A⁺ and MMP-9⁺ subcutaneous tumor cells was reduced, whereas the number of Bax⁺ cells was increased in the F1, F2, F3 and F4 groups. Additionally, in these groups, tumor expression of NF-κB, Bcl-2, VEGF-A and MMP-9 transcripts and proteins was downregulated, while Bax messenger RNA and protein expression levels were upregulated. The results revealed that fentanyl inhibits the growth of subcutaneous human gastric carcinoma tumors in mice. Therefore, it could be hypothesized that this antineoplastic activity may result from the inhibition of NF-κB activation, suppression of downstream VEGF-A and MMP-9 expression, and normalization of the pro-apoptotic Bax/Bcl-2 ratio.

Chronic morphine treatment increased the expression of myeloid differentiation primary response protein 88 in rat spinal cord

Chronic morphine exposure leads to tolerance, which limits the clinical use of this potent analgesic in the treatment of severe and chronic pain. Compelling evidence suggest that neuro-immune activation (pro-inflammatory cytokines including IL-1β, IL-6 and TNF) as well as neuro-inflammation have been shown to mediate the development of morphine analgesic tolerance. Toll-like receptors (TLRs), especially TLR-4, have also been reported to contribute to the development of morphine analgesic tolerance. Besides, mitogen-activated protein kinases (MAPKs; especially p38 MAPK and c-Jun N -terminal kinase), as well as nuclear factor-κB (NF-κB) modulate the development of morphine antinociceptive tolerance. Hence, we hypothesis the possible involvement of myeloid differentiation primary response protein 88 (MyD88), a key adaptor protein for the TLR and IL-1R families, in the development of tolerance to morphine-induced analgesia. Our study demonstrated that chronic intrathecal morphine injection led to a robust increase of MyD88 expression in rat spinal cord. Sustained elevation of MyD88 may play a role in modulating the development of morphine antinociceptive tolerance.

Anti-inflammatory effects of ethanolic extract from Sargassum horneri (Turner) C. Agardh on lipopolysaccharide-stimulated macrophage activation via NF-κB pathway regulation

Inflammation is major symptom of the innate immune response by infection of microbes. Macrophages, one of immune response related cells, play a role in inflammatory response. Recent studies reported that various natural products can regulate the activation of immune cells such as macrophage. Sargassum horneri (Turner) C. Agardh is one of brown algae. Recently, various seaweeds including brown algae have antioxidant and anti-inflammatory effects. However, anti-inflammatory effects of Sargassum horneri (Turner) C. Agardh are still unknown. In this study, we investigated anti-inflammatory effects of ethanolic extract of Sargassum horneri (Turner) C. Agardh (ESH) on RAW 264.7 murine macrophage cell line. The ESH was extracted from dried Sargassum horneri (Turner) C. Agardh with 70% ethanol and then lyophilized at -40 °C. ESH was not cytotoxic to RAW 264.7, and nitric oxide (NO) production induced by LPS-stimulated macrophage activation was significantly decreased by the addition of 200 μg/mL of ESH. Moreover, ESH treatment reduced mRNA level of cytokines, including IL-1β, and pro-inflammatory genes such as iNOS and COX-2 in LPS-stimulated macrophage activation in a dose-dependent manner. ESH was found to elicit anti-inflammatory effects by inhibiting ERK, p-p38 and NF-κB phosphorylation. In addition, ESH inhibited the release of IL-1β in LPS-stimulated macrophages. These results suggest that ESH elicits anti-inflammatory effects on LPS-stimulated macrophage activation via the inhibition of ERK, p-p38, NF-κB, and pro-inflammatory gene expression.

Toll-like receptors expression and NF-κB activation in peritoneal leukocytes in morphine-mediated impairment of zymosan-induced peritonitis in swiss mice

Zymosan-induced peritonitis represents a well-described model of acute inflammation. The binding of zymosan with its specific Toll-like receptors (TLR2 and TLR6) on leukocytes initiates activation and phosphorylation of nuclear factor (NF)-κB, which leads to accumulation of NF-κB p65 subunits in the nucleus and subsequently up-regulation of the proinflammatory cytokine genes expression. Intraperitoneal co-administration of zymosan and morphine significantly inhibits peritonitis in several strains of mice by decreasing the influx of exudatory cells; however, mechanisms of this action still remain unclear. We aimed to verify the effects of morphine on NF-κB and TLRs expression at messenger RNA and protein levels during the early stages of zymosan-induced peritonitis. Peritonitis was induced by a single injection of zymosan A or zymosan supplemented with morphine in Swiss mice. At selected time points, after stimulation, peritoneal leukocytes were harvested. The TLRs and NF-κB expression was assessed by real-time PCR and flow cytometry. In comparison with the mice injected with zymosan only, morphine co-injection significantly decreased the expression of phospho-NF-κB and TLR2 in all investigated immunocompetent cells as well as up-regulated the levels of nitric oxide (NO) in peritoneal fluid. Moreover, supplementation of zymosan with morphine altered the TLR, NF-κB and some proinflammatory cytokines (keratinocyte-derived chemokine, tumor necrosis factor-α) gene expression during ongoing inflammation. We may postulate that after morphine stimulation peritoneal leukocytes recognize less effectively zymosan antigens because of impaired TLRs expression. The lower TLR expression attenuates TLR-mediated signal transduction, which prevents NF-κB activation. Additionally, during zymosan-induced peritonitis, morphine may modulate the NF-κB expression, at least partially, by an up-regulated release of NO, as suggested by others.

Immunological modifications induced from products used during the perioperative period

Anesthetics and other products used during the perioperative period may influence immune function not only merely by reducing the HPA-axis stress response but also by directly modulating innate and adaptive immune responses. Most of the literature on the immune effects of anesthetics has been derived from in vitro or animal studies, due to the number of confounding variables in real life surgical settings. These immunosuppressive effects might not normally have clinical consequences for an immune-competent patient, but may act as important modifiers in postoperative morbidity and mortality. Furthermore, some inhibitory effects on neutrophil functions may provide a therapeutically beneficial effect under specific surgical clinical conditions, such as ischemia-reperfusion injury.

Dopamine, morphine, and nitric oxide: an evolutionary signaling triad

Morphine biosynthesis in relatively simple and complex integrated animal systems has been demonstrated. Key enzymes in the biosynthetic pathway have also been identified, that is, CYP2D6 and COMT. Endogenous morphine appears to exert highly selective actions via novel mu opiate receptor subtypes, that is, mu3,-4, which are coupled to constitutive nitric oxide release, exerting general yet specific down regulatory actions in various animal tissues. The pivotal role of dopamine as a chemical intermediate in the morphine biosynthetic pathway in plants establishes a functional basis for its expansion into an essential role as the progenitor catecholamine signaling molecule underlying neural and neuroendocrine transmission across diverse animal phyla. In invertebrate neural systems, dopamine serves as the preeminent catecholamine signaling molecule, with the emergence and limited utilization of norepinephrine in newly defined adaptational chemical circuits required by a rapidly expanding set of physiological demands, that is, motor and motivational networks. In vertebrates epinephrine, emerges as the major end of the catecholamine synthetic pathway consistent with a newly incorporated regulatory modification. Given the striking similarities between the enzymatic steps in the morphine biosynthetic pathway and those driving the evolutionary adaptation of catecholamine chemical species to accommodate an expansion of interactive but distinct signaling systems, it is our overall contention that the evolutionary emergence of catecholamine systems required conservation and selective "retrofit" of specific enzyme activities, that is, COMT, drawn from cellular morphine expression. Our compelling hypothesis promises to initiate the reexamination of clinical studies, adding new information and treatment modalities in biomedicine.

Anesthetics, immune cells, and immune responses

General anesthesia accompanied by surgical stress is considered to suppress immunity, presumably by directly affecting the immune system or activating the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Along with stress such as surgery, blood transfusion, hypothermia, hyperglycemia, and postoperative pain, anesthetics per se are associated with suppressed immunity during perioperative periods because every anesthetic has direct suppressive effects on cellular and neurohumoral immunity through influencing the functions of immunocompetent cells and inflammatory mediator gene expression and secretion. Particularly in cancer patients, immunosuppression attributable to anesthetics, such as the dysfunction of natural killer cells and lymphocytes, may accelerate the growth and metastases of residual malignant cells, thereby worsening prognoses. Alternatively, the anti-inflammatory effects of anesthetics may be beneficial in distinct situations involving ischemia and reperfusion injury or the systemic inflammatory response syndrome (SIRS). Clinical anesthesiologists should select anesthetics and choose anesthetic methods with careful consideration of the clinical situation and the immune status of critically ill patients, in regard to long-term mortality, morbidity, and the optimal prognosis.

A novel hybrid aspirin-NO-releasing compound inhibits TNFalpha release from LPS-activated human monocytes and macrophages

Background

The cytoprotective nature of nitric oxide (NO) led to development of NO-aspirins in the hope of overcoming the gastric side-effects of aspirin. However, the NO moiety gives these hybrids potential for actions further to their aspirin-mediated anti-platelet and anti-inflammatory effects. Having previously shown that novel NO-aspirin hybrids containing a furoxan NO-releasing group have potent anti-platelet effects, here we investigate their anti-inflammatory properties. Here we examine their effects upon TNFα release from lipopolysaccharide (LPS)-stimulated human monocytes and monocyte-derived macrophages and investigate a potential mechanism of action through effects on LPS-stimulated nuclear factor-kappa B (NF-κB) activation.

Methods

Peripheral venous blood was drawn from the antecubital fossa of human volunteers. Mononuclear cells were isolated and cultured. The resultant differentiated macrophages were treated with pharmacologically relevant concentrations of either a furoxan-aspirin (B8, B7; 10 μM), their respective furazan NO-free counterparts (B16, B15; 10 μM), aspirin (10 μM), existing nitroaspirin (NCX4016; 10 μM), an NO donor (DEA/NO; 10 μM) or dexamethasone (1 μM), in the presence and absence of LPS (10 ng/ml; 4 h). Parallel experiments were conducted on undifferentiated fresh monocytes. Supernatants were assessed by specific ELISA for TNFα release and by lactate dehydrogenase (LDH) assay for cell necrosis. To assess NF-κB activation, the effects of the compounds on the loss of cytoplasmic inhibitor of NF-κB, IκBα (assessed by western blotting) and nuclear localisation (assessed by immunofluorescence) of the p65 subunit of NF-κB were determined.

Results

B8 significantly reduced TNFα release from LPS-treated macrophages to 36 ± 10% of the LPS control. B8 and B16 significantly inhibited monocyte TNFα release to 28 ± 5, and 49 ± 9% of control, respectively. The B8 effect was equivalent in magnitude to that of dexamethasone, but was not shared by 10 μM DEA/NO, B7, the furazans, aspirin or NCX4016. LDH assessment revealed none of the treatments caused significant cell lysis. LPS stimulated loss of cytoplasmic IκBα and nuclear translocation of the p65 NF-κB subunit was inhibited by the active NO-furoxans.

Conclusion

Here we show that furoxan-aspirin, B8, significantly reduces TNFα release from both monocytes and macrophages and suggest that inhibition of NF-κB activation is a likely mechanism for the effect. This anti-inflammatory action highlights a further therapeutic potential of drugs of this class.

Cytokines and coronary artery disease: the state of the art

Initiation and progression of coronary atherosclerosis has been associated with inflammation and cytokines balance. The objective of this study is to understand the role of cytokines in the pathophysiology and management of coronary artery disease. Coronary artery disease has been revisited with revision of the pertinent published articles in the Medline, Scopus, and EBSCO Host research from 1987 to 2007. The 2 groups of cytokines (proinflammatory and anti-inflammatory) have been detected in human atherosclerotic plaques. The balance between the 2 groups may reflect the intensity of occult plaque inflammation and the vulnerability to rupture. Multiple studies have determined that a diverse set of proinflammatory biomarkers can furnish prognostic information beyond the traditional risk factors. Inflammatory responses after coronary revascularization are known to play key role in vascular lesion formation early in atherosclerosis and restenosis. Clinical utilization of cytokines remains promising yet incompletely explored and need more studies.

Chronic inflammation in the cystic fibrosis lung: alterations in inter- and intracellular signaling

A vicious cycle of airway obstruction, infection, and inflammation continues to cause most of the morbidity and mortality in cystic fibrosis (CF). Mutations that result in decreased expression or function of the membrane Cl(-) channel, cystic fibrosis transmembrane regulator (CFTR), result in a decrease in the volume (and hence the depth) of liquid on the airway surface, impaired ciliary function, and dehydrated glandular secretions. In turn, these abnormalities contribute to a milieu, which promotes chronic infection with a limited but unique spectrum of microorganisms. Defects in CFTR also perturb regulation of several intracellular signaling pathways including signal transducers and activator of transcription, I-kappaB and nuclear factor-kappa B, and low molecular weight GTPases. Together, these abnormalities result in excessive production of NF-kappaB dependent cytokines such as interleukin (IL)-1, tumor necrosis factor (TNF), IL-6, and IL-8. There are decreased responses to interferon gamma and transforming growth factor beta leading to decreased production of iNOS and NO. Abnormalities of lipid mediators and decreased secretion of counter/regulatory cytokines have also been reported. Together, these effects combine to create a chronic inflammatory process, which damages and obstructs the airways, and eventually claims the life of the patient.

Endogenous morphine/nitric oxide-coupled regulation of cellular physiology and gene expression: implications for cancer biology

Cancer is a simplistic, yet complicated, process that promotes uncontrolled growth. In this regard, this unconstrained proliferation may represent primitive phenomena whereby cellular regulation is suspended or compromised. Given the new empirical evidence for a morphinergic presence and its profound modulatory actions on several cellular processes it is not an overstatement to hypothesize that morphine may represent a key chemical messenger in the process of modulating proliferation of diverse cells. This has been recently demonstrated by the finding of a novel opiate-alkaloid selective receptor subtype in human multilineage progenitor cells (MLPC). Adding to the significance of morphinergic signaling are the findings of its presence in plant, invertebrate and vertebrate cells, which also have been shown to synthesize this messenger as well. Interestingly, we and others have shown that some cancerous tissues contain morphine. Furthermore, in medullary histolytic reticulosis, which is exemplified by cells having hyperactivity, the mu3 (mu3) opiate select receptor was not present. Thus, it would appear that morphinergic signaling has inserted itself in many processes taking a long time to evolve, including those regulating the proliferation of cells across diverse phyla.

Nuclear factor kappaB signaling in opioid functions and receptor gene expression

Opiates are the most powerful of all known analgesics. The prototype opiate morphine has been used as a painkiller for several thousand years. Chronic usage of opiates not only causes drug tolerance, dependence, and addiction, but also suppresses immune functions and affects cell proliferation and cell survival. The diverse functions of opiates underscore the complexity of opioid receptor signaling. Several downstream signaling effector systems, including adenylyl cyclase, mitogen-activated protein kinase, Ca2+ channels, K+ channels, and phosphatidylinositol 3-kinase/Akt, have been identified to be critical in opioid functions. Nuclear factor-kappaB (NF-kappaB), one of the most diverse and critical transcription factors, is one of the downstream molecules that may either directly or indirectly transmit the receptor-mediated upstream signals to the nucleus, resulting in the regulation of the NF-kappaB-dependent genes, which are critical for the opioid-induced biological responses of neuronal and immune cells. In this minireview, we focus on current understanding of the involvement of NF-kappaB signaling in opioid functions and receptor gene expression in cells.

Expression and regulation of the mu opioid peptide receptor in TPA-differentiated HL-60 promyelocytic leukemia cells

Cellular differentiation of immune cells involves an array of molecular events responsible for their commitment to cellular maturation. Treatment of HL-60 promyelocytic leukemia cells with 12-o-tetradecanoyl-phorbol-13-acetate (TPA) induces the cells to differentiate into monocyte/macrophage-like cells. In this study, following TPA treatment, there was a significant increase in mu opioid peptide receptor (MOPR) mRNA levels in the differentiated HL-60 cells as measured by quantitative-competitive RT-PCR (QC-RT-PCR) and real-time RT-PCR. Morphine's inhibition of forskolin-induced intracellular cAMP confirmed the functionality of the MOPR. TPA-induced differentiation also significantly enhanced the binding activities of two transcriptional factors, AP-1 and NFkB. Prolonged treatment of the TPA-differentiated HL-60 cells with morphine down-regulated MOPR mRNA expression and decreased the binding activities of AP-1 and NFkB, both of which were naloxone reversible. Thus, the direct correlation between AP-1 and NFkB binding activities and MOPR expression in HL-60 cells following TPA-induced differentiation as well as in TPA-differentiated HL-60 cells given prolonged treatment with morphine suggests that transcriptional factors, such as AP-1 and NFkB, may play a role in the molecular mechanisms underlying regulation of MOPR expression in immune cells.

Immunomodulatory effect of morphine: therapeutic implications

The immunosuppressive as well as modulatory effects of morphine have been known in clinical medicine for > 100 years. Recent developments in molecular immunology, including experiments in mu (mu) opioid receptor knockout mice has led to a better understanding of central and peripheral mechanisms involved in this process. Though there is a large volume of literature documenting adverse effects of immunosupression following the use of morphine, several reports confirm its potential usefulness as an immunomodulator. In vitro and in vivo animal experiments have demonstrated wide-spectrum effects of morphine, including anti-inflammatory, antifibrotic, antitumour, cardioprotective and renoprotective. Immunomodulation is an important field in modern medicine with rapid advancement in recent years. Though a final statement regarding the clinical relevance of morphine-induced immunomodulation cannot be made at this juncture, nevertheless, it is worthwhile to review current developments. It may encourage further clinical studies to elucidate the influence of morphine treatment on immune regulation in different specialties of medicine.

Expression of opioid receptor subtypes and their ligands in fibrillating human atria

The delta- and kappa-receptor subtypes are both abundantly expressed in the human heart and participate in age- and stress-related alterations of cardiac function. Opioid receptor agonists mediate cardioprotection in response to ischemic preconditioning via increased intracellular Ca(2) (+) levels, opening mitochondrial K(ATP) channels, and PKC activation. We studied the expression of opioid receptor subtypes kappa and delta, and of their ligand precursors, proopiomelanocortin (POMC) and preproenkephalin A (PENKA), in human atrial tissue of patients in sinus rhythm (SR), or persistent atrial fibrillation (AF). The mitochondrial size was also compared between the two groups. The atrial mRNA expression of opioid peptide precursors and receptors was assessed by competitive and real-time RT-PCR in 16 patients in AF and 16 patients in SR. Mitochondria were analyzed in the atrial tissue by electron microscopy in four patients in AF and four patients in SR. Both PENKA (SR: 100 +/- 33% vs AF: 33 +/- 21%; P < 0.05) and kappa-receptor mRNA amounts (AF: 78 +/- 20% vs SR: 100 +/- 11%; P < 0.05) were both decreased in AF in comparison to SR. In addition, POMC mRNA levels were decreased in AF (SR: 100 +/- 54% vs AF: 37 +/- 26%; P < 0.05), whereas the expression of the corresponding delta-opioid receptor was unchanged (AF: 102 +/- 34% vs 100 +/- 44%). Mitochondrial size was increased during persistent AF. Persistent AF is associated with the down-regulation of the opioid receptor/ligand expression. This suggests a loss of protective capacity in the fibrillating atrial tissue, resulting in an ultrastructural remodeling of atrial myocytes.

Vascular basis of Alzheimer's pathogenesis

Considerable evidence now indicates that Alzheimer's disease (AD) is primarily a vascular disorder. This conclusion is supported by the following evidence: (1) epidemiologic studies linking vascular risk factors to cerebrovascular pathology that can set in motion metabolic, neurodegenerative, and cognitive changes in Alzheimer brains; (2) evidence that AD and vascular dementia (VaD) share many similar risk factors; (3) evidence that pharmacotherapy that improves cerebrovascular insufficiency also improves AD symptoms; (4) evidence that preclinical detection of potential AD is possible from direct or indirect regional cerebral perfusion measurements; (5) evidence of overlapping clinical symptoms in AD and VaD; (6) evidence of parallel cerebrovascular and neurodegenerative pathology in AD and VaD; (7) evidence that cerebral hypoperfusion can trigger hypometabolic, cognitive, and degenerative changes; and (8) evidence that AD clinical symptoms arise from cerebromicrovascular pathology. The collective data presented in this review strongly indicate that the present classification of AD is incorrect and should be changed to that of a vascular disorder. Such a change in classification would accelerate the development of better treatment targets, patient management, diagnosis, and prevention of this disorder by focusing on the root of the problem. In addition, a theoretical capsule summary is presented detailing how AD may develop from chronic cerebral hypoperfusion and the role of critically attained threshold of cerebral hypoperfusion (CATCH) and of vascular nitric oxide derived from endothelial nitric oxide synthase in triggering the cataclysmic cerebromicrovascular pathology.

The role of nitric oxide in anticonvulsant and proconvulsant effects of morphine in mice

Acute subcutaneous administration of lower doses of morphine (0.5, 1 and 3 mg/kg) increase the threshold of seizures induced by pentylenetetrazole (PTZ) in mice, whereas higher doses of morphine (15, 30 and 60 mg/kg) have proconvulsant effects. The effect of systemic administration of nitric oxide synthase (NOS) inhibitors N(G)-nitro-L-arginine methyl ester (L-NAME) and N(G)-nitro-L-arginine (L-NNA) and nitric oxide synthase (NOS) L-arginine on biphasic effect of morphine was investigated. Acute administration of both L-NAME (1, 3 and 10 mg/kg) and L-NNA (1 and 10 mg/kg) as well as chronic pretreatment with L-NAME (1 and 10 mg/kg, 4 days) dose-dependently inhibited both the anticonvulsant and proconvulsant effects of morphine (1 and 30 mg/kg, respectively). The inhibition was complete for anticonvulsant effect while partial for proconvulsant effect. L-arginine at doses that did not affect seizure threshold per se (acute, 30 and 60 mg/kg; chronic, 60 mg/kg) potentiated both anticonvulsant and proconvulsant properties of less potent doses of morphine (0.5 and 15 mg/kg, respectively). The L-arginine induced potentiation of both phases of morphine effect was blocked by L-NAME (0.5-30 mg/kg). Moreover, low and per se non-effective doses of naloxone (0.1 mg/kg) and L-NAME (0.3, 0.5 or 1 mg/kg) showed additive effects in inhibiting both phases of morphine effects. These results support the involvement of L-arginine/nitric oxide pathway in the modulation of seizure threshold by morphine.

Increased production of inflammatory cytokines in patients with silent myocardial ischemia

OBJECTIVES

The aim of the study was to examine the inflammatory cytokines in patients with myocardial ischemia to evaluate whether silent ischemia patients exhibit any particular cytokine pattern.

BACKGROUND

Silent myocardial ischemia is frequently observed in patients with coronary artery disease. Various endogenous mechanisms control a patient's perceived intensity of pain. Among them, the inflammatory process and the related cytokine production are known to modulate the threshold for activating the primary afferent nociceptors.

METHODS

Seventy-eight patients with reproducible exercise-induced myocardial ischemia were studied: 34 symptomatic patients, with rest and/or stress angina; 44 asymptomatic patients, with no symptoms during daily life activities or during positive exercise stress test. Venous blood samples were taken from all patients to evaluate the expression of CD11b receptors both on neutrophils and monocytes. Frozen plasma samples (at -80 degrees C) were used to quantify the anti-inflammatory (interleukin-4 and -10, transforming growth factor-beta) and the proinflammatory cytokines (tumor necrosis factor-alpha, interferon-gamma, interleukin-1beta and -6).

RESULTS

In asymptomatic patients lower CD11b receptor expression and higher concentration of anti-inflammatory cytokines were observed. Proinflammatory cytokine production was similar in the two groups.

CONCLUSIONS

The data suggest that an "anti-inflammatory pattern" of cytokine production correlates with silent ischemia and that the immune and inflammatory system activation may be crucial for angina symptoms.

Evidence that Alzheimer's disease is a microvascular disorder: the role of constitutive nitric oxide

Evidence is fast accumulating which indicates that Alzheimer's disease is a vascular disorder with neurodegenerative consequences rather than a neurodegenerative disorder with vascular consequences. It is proposed that two factors need to be present for AD to develop: (1) advanced ageing, (2) presence of a condition that lowers cerebral perfusion, such as a vascular-risk factor. The first factor introduces a normal but potentially insidious process that lowers cerebral blood flow in inverse relation to increased ageing; the second factor adds a crucial burden which further lowers brain perfusion and places vulnerable neurons in a state of high energy compromise leading to a cascade of neuronal metabolic turmoil. Convergence of the two factors above will culminate in a critically attained threshold of cerebral hypoperfusion (CATCH). CATCH is a hemodynamic microcirculatory insufficiency that will destabilize neurons, synapses, neurotransmission and cognitive function, creating in its wake a neurodegenerative state characterized by the formation of senile plaques, neurofibrillary tangles, amyloid angiopathy and in some cases, Lewy bodies. Since any of a considerable number of vascular-related conditions must be present in the ageing individual for cognition to be disturbed, CATCH identifies an important aspect of the heterogeneic disease profile assumed to be present in the AD syndrome. It is proposed that CATCH initiates AD by distorting regional brain capillary structure involving endothelial cell shape changes and impairment of nitric oxide (NO) release which affect signaling between the immune, cardiovascular and nervous systems. Evidence is presented that in many tissues there is a basal level of NO being produced and that the actions of several signaling molecules may initiate increases in basal NO levels. Moreover, these temporary increases in basal NO levels exert inhibitory cellular actions, via cellular conformational changes. Findings indicate that (a) constitutive NO is responsible for a basal or 'tonal' level of NO; (b) this NO keeps particular types of cells in a state of inhibition and (c) activation of these cells occurs through disinhibition. Consequently, tissues not maintaining a basal NO level are more prone to excitatory, immune, vascular and neural influences. Under such circumstances, these tissues cannot be down-regulated to normal basal levels, thus prolonging their excitatory state. Thus, the clinical convergence of advanced ageing in the presence of a chronic, pre-morbid vascular risk factor, can, in time, contribute to an endotheliopathy involving basal NO deficit, to the degree where regional metabolic dysfunction leads to cognitive meltdown and to progressive neurodegeneration characteristic of Alzheimer's disease.