A pilot trial of low-dose naltrexone in primary progressive multiple sclerosis

A sixth month phase II multicenter-pilot trial with a low dose of the opiate antagonist Naltrexone (LDN) has been carried out in 40 patients with primary progressive multiple sclerosis (PPMS). The primary end points were safety and tolerability. Secondary outcomes were efficacy on spasticity, pain, fatigue, depression, and quality of life. Clinical and biochemical evaluations were serially performed. Protein concentration of beta-endorphins (BE) and mRNA levels and allelic variants of the mu-opiod receptor gene (OPRM1) were analyzed. Five dropouts and two major adverse events occurred. The remaining adverse events did not interfere with daily living. Neurological disability progressed in only one patient. A significant reduction of spasticity was measured at the end of the trial. BE concentration increased during the trial, but no association was found between OPRM1 variants and improvement of spasticity. Our data clearly indicate that LDN is safe and well tolerated in patients with PPMS.

The prokineticin receptor agonist Bv8 decreases IL-10 and IL-4 production in mice splenocytes by activating prokineticin receptor-1

Background

Bv8, prokineticin-1, or endocrine gland-vascular endothelial growth factor, and prokineticin-2 are recently isolated peptide agonists of two G protein-coupled receptors, prokineticin receptor-1 (PROKR 1) and PROKR 2, and have been described as affecting a number of myeloid cell functions. We evaluated the impact of Bv8 on lymphoid cells by investigating its ability to modulate T cell cytokine balance in mouse.

Results

The production of T-helper1 cytokines (IL-2, IFN-γ and IL-1β), the T-helper 2 cytokine IL-4, and the anti-inflammatory cytokine IL-10 by mouse splenocytes was evaluated after polyclonal stimulation or immunisation with the keyhole limpet hemocyanin protein antigen by measuring cytokine levels. When added in vitro to Con-A-stimulated splenocytes, Bv8 significantly increased IL-1β and decreased IL-4 and IL-10; IL-2 and IFN-γ were not affected. Similar results were obtained when Bv8 was administered in vivo. In KLH-immunised mice, splenocytes restimulated in vitro with KLH and Bv8 produced significantly smaller amounts of IL-4 and IL-10. KLH-induced IL-10 and IL-4 production was also significantly blunted in animals administered Bv8 in vivo at the time of KLH immunisation or two weeks later. The Bv8-induced effects were lost in mice lacking the PROKR 1 gene, thus indicating that PROKR 1 is the receptor involved in the modulation of cytokines.

Conclusion

These findings indicate that Bv8/prokineticin-1 is a novel modulator of lymphoid functions, and may be a suitable target for new immunopharmacological strategies.

Genistein, a natural phytoestrogen from soy, relieves neuropathic pain following chronic constriction sciatic nerve injury in mice: anti-inflammatory and antioxidant activity

There is great interest in soy isoflavones as alternatives to endogenous estrogens not only in hormonal pathologies, but also in inflammatory, neurodegenerative diseases, and pain. We investigated the effect of the isoflavone genistein on neuropathic pain. Genistein binds estrogen receptors (ER) with higher affinity for the ERbeta particularly expressed in neuronal and immune cells. Neuropathy was induced in mice by means of chronic sciatic nerve constriction, and the subcutaneous administration of genistein from the third day after the lesion reversed pain hypersensitivity in a time- and dose-dependent manner. This effect may have been due to the activation of classical nuclear receptor and/or anti-oxidant, anti-inflammatory, and immunomodulating properties of genistein. The fact that a specific ERbeta antagonist prevented both its anti-allodynic and anti-hyperalgesic action, whereas a specific ERalpha antagonist was ineffective and a non-selective ER antagonist only reversed the anti-allodynic effect, suggests the involvement of ERbeta. Antioxidant effects are also involved as the anti-nociceptive dose reversed the increase in reactive oxygen species and malondialdehyde in injured paw tissues, and increased the activity of anti-oxidant enzymes. The phytoestrogen had immunomodulatory and anti-inflammatory activities as it reduced peripheral and central nuclear factor-kappaB, nitric oxide system and pro-inflammatory cytokine over-activation. Taken together, our results suggest that genistein could ameliorate painful neuropathy by multiple mechanisms.

The VGF-derived peptide TLQP-21: a new modulatory peptide for inflammatory pain

Vgf, is a neuro-endocrine specific gene encoding for a large protein precursor of different peptides. A role for VGF in pain modulation has been suggested from immunohistochemical studies showing VGF mRNA widely expressed in primary sensory neurons. In this study, the presence of VGF on the primary sensory afferents in mice was confirmed by showing its immunostaining in cultured neurons of dorsal root ganglia in secretory granule varicosities colocalized with Substance P. Moreover, the functional role of a C-terminal internal VGF-derived peptide, i.e. TLQP-21, was assessed by investigating its peripheral (1, 2, 4, 8mM) and central (1, 2, 4 mM) effects on inflammatory pain in the formalin test. A significant increase of pain-related licking response following peripheral injection of TLQP-21 (4 and 8mM) was observed in the second inflammatory phase of the test. In addition, an increase in licking response was detected when 4 mM of the peptide was injected alone without formalin. On the other hand, the central administration of TLQP-21 induced an U-shaped curve, with the dose of 2 mM being analgesic during the second phase. This study shows for the first time that a VGF-derived peptide may be involved in inflammatory pain in vivo and demonstrates a different action for TLQP21 at the peripheral and central levels of the nociceptive pathways.

The purinergic antagonist PPADS reduces pain related behaviours and interleukin-1β, interleukin-6, iNOS and nNOS overproduction in central and peripheral nervous system after peripheral neuropathy in mice

Neuropathic pain consequent to peripheral injury is associated with local inflammation and overexpression of nitric oxide synthases (NOS) and inflammatory cytokines in locally recruited macrophages, Schwann and glial cells. We investigated the time course and localization of nitric oxide synthases (NOS) and cytokines in the central (spinal cord and thalamus) and peripheral nervous system (nerve and dorsal root ganglia), in a mouse model of mononeuropathy induced by sciatic nerve chronic constriction injury. ATP is recognized as an endogenous pain mediator. Therefore we also evaluated the role of purinergic signalling in pain hypersensitivity employing the P2 receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS), on pain behaviour, NOS and cytokines. The PPADS daily administration starting on day 3 after injury dose- and time-dependently decreased both tactile allodynia and thermal hyperalgesia. PPADS (25mg/kg) completely reversed nociceptive hypersensitivity and simultaneously reduced the increased NO/NOS system and IL-1beta in both peripheral (injured sciatic nerve and L4-L6 ipsilateral dorsal root ganglia) and central steps of nervous system (L4-L6 spinal cord and thalamus) involved in pain signalling. IL-6 was overexpressed only in the peripheral nervous system and PPADS prolonged administration reduced it in sciatic nerve. In conclusion, we hypothesize that NO/NOS and IL-1beta have a pronociceptive role in this neuropathy model, and that purinergic antagonism reduces pain hypersensitivity by inhibiting their overactivity.

Opioids and the management of chronic severe pain in the elderly: consensus statement of an International Expert Panel with focus on the six clinically most often used World Health Organization Step III opioids (buprenorphine, fentanyl, hydromorphone, methadone, morphine, oxycodone)

SUMMARY OF CONSENSUS: 1. The use of opioids in cancer pain: The criteria for selecting analgesics for pain treatment in the elderly include, but are not limited to, overall efficacy, overall side-effect profile, onset of action, drug interactions, abuse potential, and practical issues, such as cost and availability of the drug, as well as the severity and type of pain (nociceptive, acute/chronic, etc.). At any given time, the order of choice in the decision-making process can change. This consensus is based on evidence-based literature (extended data are not included and chronic, extended-release opioids are not covered). There are various driving factors relating to prescribing medication, including availability of the compound and cost, which may, at times, be the main driving factor. The transdermal formulation of buprenorphine is available in most European countries, particularly those with high opioid usage, with the exception of France; however, the availability of the sublingual formulation of buprenorphine in Europe is limited, as it is marketed in only a few countries, including Germany and Belgium. The opioid patch is experimental at present in U.S.A. and the sublingual formulation has dispensing restrictions, therefore, its use is limited. It is evident that the population pyramid is upturned. Globally, there is going to be an older population that needs to be cared for in the future. This older population has expectations in life, in that a retiree is no longer an individual who decreases their lifestyle activities. The "baby-boomers" in their 60s and 70s are "baby zoomers"; they want to have a functional active lifestyle. They are willing to make trade-offs regarding treatment choices and understand that they may experience pain, providing that can have increased quality of life and functionality. Therefore, comorbidities--including cancer and noncancer pain, osteoarthritis, rheumatoid arthritis, and postherpetic neuralgia--and patient functional status need to be taken carefully into account when addressing pain in the elderly. World Health Organization step III opioids are the mainstay of pain treatment for cancer patients and morphine has been the most commonly used for decades. In general, high level evidence data (Ib or IIb) exist, although many studies have included only few patients. Based on these studies, all opioids are considered effective in cancer pain management (although parts of cancer pain are not or only partially opioid sensitive), but no well-designed specific studies in the elderly cancer patient are available. Of the 2 opioids that are available in transdermal formulation--fentanyl and buprenorphine--fentanyl is the most investigated, but based on the published data both seem to be effective, with low toxicity and good tolerability profiles, especially at low doses. 2. The use of opioids in noncancer-related pain: Evidence is growing that opioids are efficacious in noncancer pain (treatment data mostly level Ib or IIb), but need individual dose titration and consideration of the respective tolerability profiles. Again no specific studies in the elderly have been performed, but it can be concluded that opioids have shown efficacy in noncancer pain, which is often due to diseases typical for an elderly population. When it is not clear which drugs and which regimes are superior in terms of maintaining analgesic efficacy, the appropriate drug should be chosen based on safety and tolerability considerations. Evidence-based medicine, which has been incorporated into best clinical practice guidelines, should serve as a foundation for the decision-making processes in patient care; however, in practice, the art of medicine is realized when we individualize care to the patient. This strikes a balance between the evidence-based medicine and anecdotal experience. Factual recommendations and expert opinion both have a value when applying guidelines in clinical practice. 3. The use of opioids in neuropathic pain: The role of opioids in neuropathic pain has been under debate in the past but is nowadays more and more accepted; however, higher opioid doses are often needed for neuropathic pain than for nociceptive pain. Most of the treatment data are level II or III, and suggest that incorporation of opioids earlier on might be beneficial. Buprenorphine shows a distinct benefit in improving neuropathic pain symptoms, which is considered a result of its specific pharmacological profile. 4. The use of opioids in elderly patients with impaired hepatic and renal function: Functional impairment of excretory organs is common in the elderly, especially with respect to renal function. For all opioids except buprenorphine, half-life of the active drug and metabolites is increased in the elderly and in patients with renal dysfunction. It is, therefore, recommended that--except for buprenorphine--doses be reduced, a longer time interval be used between doses, and creatinine clearance be monitored. Thus, buprenorphine appears to be the top-line choice for opioid treatment in the elderly. 5. Opioids and respiratory depression: Respiratory depression is a significant threat for opioid-treated patients with underlying pulmonary condition or receiving concomitant central nervous system (CNS) drugs associated with hypoventilation. Not all opioids show equal effects on respiratory depression: buprenorphine is the only opioid demonstrating a ceiling for respiratory depression when used without other CNS depressants. The different features of opioids regarding respiratory effects should be considered when treating patients at risk for respiratory problems, therefore careful dosing must be maintained. 6. Opioids and immunosuppression: Age is related to a gradual decline in the immune system: immunosenescence, which is associated with increased morbidity and mortality from infectious diseases, autoimmune diseases, and cancer, and decreased efficacy of immunotherapy, such as vaccination. The clinical relevance of the immunosuppressant effects of opioids in the elderly is not fully understood, and pain itself may also cause immunosuppression. Providing adequate analgesia can be achieved without significant adverse events, opioids with minimal immunosuppressive characteristics should be used in the elderly. The immunosuppressive effects of most opioids are poorly described and this is one of the problems in assessing true effect of the opioid spectrum, but there is some indication that higher doses of opioids correlate with increased immunosuppressant effects. Taking into consideration all the very limited available evidence from preclinical and clinical work, buprenorphine can be recommended, while morphine and fentanyl cannot. 7. Safety and tolerability profile of opioids: The adverse event profile varies greatly between opioids. As the consequences of adverse events in the elderly can be serious, agents should be used that have a good tolerability profile (especially regarding CNS and gastrointestinal effects) and that are as safe as possible in overdose especially regarding effects on respiration. Slow dose titration helps to reduce the incidence of typical initial adverse events such as nausea and vomiting. Sustained release preparations, including transdermal formulations, increase patient compliance.

Immunomodulation with glatiramer acetate prevents long-term inflammatory pain

The potential application of glatiramer acetate (GA) therapy as a safe pharmacological treatment for the attenuation or prevention of long-term inflammatory pain in a rat model was explored. Peripheral inflammatory pain was induced by an injection of Complete Freund's Adjuvant (CFA) into the plantar surface of the hind paw. Genome-wide DNA microarray studies were used to survey molecular mechanisms involved in long-term GA analgesic responses. Administration of a single or double subcutaneous injection of GA before, or immediately after, intraplantar injection of pro-inflammatory CFA significantly attenuated allodynia and hyperalgesic pain responses up to approximately 3 weeks after CFA treatment. These beneficial effects of GA immunization therapy coincided with the attenuation of expression of the chemotactic fractalkine chemokine (CX3CL1) in the dorsal horn of the lumbar spinal cord (L4-L5) in response to CFA treatment, assessed by DNA microarray and confirmed immunocytochemically (ICC). This study is consistent with the hypothesis that a novel mechanism through which GA immunization therapy may beneficially influence long-term allodynia and hyperalgesia is through central regulation of fractalkine-mediated responses.

Buprenorphine and methadone maintenance treatment of heroin addicts preserves immune function

Opiate addiction influences many physiological functions including immune responses. The objective of this study was to investigate the immune system function in heroin addicted patients submitted to methadone or buprenorphine maintenance treatment compared to untreated heroin addicts and healthy controls. Four groups were studied: group A included nine heroin addicted subjects, who were still injecting heroin; groups B and C were composed of 12 patients previously addicted to heroin, being treated with methadone (mean dosage 58+/-12.7 mg/day) or buprenorphine (mean dose 9.3+/-2.3mg/day) since at least 6 months; group D was composed of 15 sex and age matched healthy controls. Lymphoproliferation and peripheral mononuclear cell cultures production of the Th1 cytokines IL-2 and IFN-gamma, the Th2 cytokine IL-4, and of the pro-inflammatory cytokine TNF-alpha were evaluated in all the patients and controls. PHA-lymphoproliferation was lower in untreated heroin addicts than in controls, while it was normal in methadone and buprenorphine treated patients. An altered Th1/Th2 balance, characterized by reduced IL-4, IFN-gamma and TNF-alpha but normal IL-2 levels, was present in untreated heroin addicted subjects, while the Th1/Th2 balance was well conserved in the methadone and buprenorphine groups. These findings suggest that the immune system abnormalities in heroin addicted patients can be restored to almost normal values by controlled treatment with methadone and buprenorphine.

Effects of nimesulide on pain and on synovial fluid concentrations of substance P, interleukin-6 and interleukin-8 in patients with knee osteoarthritis: comparison with celecoxib

OBJECTIVE

This study was designed to investigate the analgesic effects of nimesulide and celecoxib in patients with knee osteoarthritis (OA). In patients with joint effusion, the effects of these non-steroidal anti-inflammatory drugs (NSAIDs) on synovial fluid concentrations of substance P (SP), interleukin (IL)-6 and IL-8 also were evaluated.

METHODS

Patients were randomly assigned either nimesulide (100 mg twice a day) or celecoxib (200 mg once a day) for 2 weeks. The intensity of joint pain was assessed with a 100-mm visual analogue scale (VAS). Furthermore, patients completed questions about analgesic efficacy and overall tolerability of the treatments on a five-point categorical scale. Synovial fluid samples were drawn at baseline, 30 min after the first drug intake (day 1), and 30 min after the last drug intake (day 14).

RESULTS

We enrolled 44 patients, 20 of whom had a joint effusion. In this group, the effects of nimesulide were more marked than for celecoxib, with evidence of a faster onset of the analgesic action. Both after a single or repeated administration, nimesulide significantly reduced the synovial fluid concentrations of SP and IL-6. Celecoxib, on the other hand, did not change the concentrations of SP and significantly reduced the levels of IL-6 only on day 14. None of the drugs affected IL-8. Both drugs were generally well tolerated.

CONCLUSIONS

These results provide evidence that nimesulide is an effective agent for the symptomatic treatment of OA. The effect on inflammatory pain mediators is consistent with the fast analgesic action of this NSAID.

Buprenorphine ameliorates the effect of surgery on hypothalamus-pituitary-adrenal axis, natural killer cell activity and metastatic colonization in rats in comparison with morphine or fentanyl treatment

Not all opioids employed in clinical practice share the same immunosuppressive properties. The potent partial micro-agonist buprenorphine appears to exhibit a neutral effect on the immune responses. Surgery stress is associated with decreased natural killer cell activity (NK) and enhancement of tumor metastasis in rats. We analyzed the ability of buprenorphine to prevent the effects of experimental surgery on HPA activation (plasma corticosterone levels), NK activity and lung diffusion of the NK sensitive tumor MADB106. Buprenorphine (0.1mg/kg) was compared with equianalgesic doses of fentanyl (0.1mg/kg) and morphine (10mg/kg) in this animal model. In normal animals morphine and fentanyl stimulate the HPA axis, decrease NK activity and augment tumor metastasis, while buprenorphine is devoid of these effects. Surgery significantly raised corticosterone levels, suppressed NK activity and increased MADB106 metastasis. Only buprenorphine was able to prevent the neuroendocrine and immune system alterations and ameliorate the increase of tumor metastasis induced by surgical stress. These preclinical findings suggest that an adequate treatment of surgically induced stress immunosuppression with an opioid drug devoid of immunosuppressive effects may also play a protective role against the metastatic diffusion following cancer surgery.

Effects of the bisphosphonate ibandronate on hyperalgesia, substance P, and cytokine levels in a rat model of persistent inflammatory pain

The anti-inflammatory and analgesic properties of different bisphosphonates have been demonstrated in both animal and human studies. Ibandronate is a third-generation bisphosphonate effective in managing different types of bone pain. In this study we investigated its effects in a standard pre-clinical model of inflammatory pain. We evaluated the effects of a single injection of different doses (0.5, 1.0, and 2.0 mg/kg i.p.) of ibandronate on inflammatory oedema and cutaneous hyperalgesia produced by the intraplantar injection of complete Freund's adjuvant (CFA) in the rat hind-paw. In addition, we measured the effects of this drug (1.0 mg/kg i.p.) on hind-paw levels of different pro-inflammatory mediators (PGE-2, SP, TNF-alpha, and IL-1beta). We also measured the levels of SP protein and of its mRNA in the ipsilateral dorsal root ganglia (DRG). Ibandronate proved able to reduce the inflammatory oedema, the hyperalgesia to mechanical stimulation, and the levels of SP in the inflamed tissue as measured 3 and 7 days following CFA-injection. This drug significantly reduced the levels of TNF-alpha and IL-1beta only on day 7. On the other hand, the levels of PGE-2 in the inflamed hind-paw were unaffected by the administration of this bisphosphonate. Finally, ibandronate blocked the overexpression of SP mRNA in DRG induced by CFA-injection in the hind-paw. These data help to complete the pharmacodynamic profile of ibandronate, while also suggesting an involvement of several inflammatory mediators, with special reference to substance P, in the analgesic action of this bisphosphonate.

Increased Tumor Necrosis Factor-α and Prostaglandin E2 Concentrations in the Cerebrospinal Fluid of Rats with Inflammatory Hyperalgesia: The Effects of Analgesic Drugs

BACKGROUND

We examined the changes in cerebrospinal fluid (CSF) concentrations of prostaglandin E2 (PGE2) and tumor necrosis factor-alpha (TNF-alpha) after intraplantar administration of complete Freund's adjuvant (CFA) in rats. In addition, we investigated whether different analgesic drugs orally administered at antihyperalgesic doses were able to prevent the changes in PGE2 and TNF-alpha spinal levels associated with hindpaw inflammation.

METHODS

The Randall-Selitto paw-withdrawal test was used to measure inflammatory hyperalgesia. Tramadol (7.5 mg/kg), paracetamol (65 mg/kg), tramadol plus paracetamol and nimesulide (5 mg/kg) were administered orally twice a day, starting from the first day after the CFA injection. PGE2 in the CSF was measured by enzyme immunoassay, and TNF-alpha by ELISA. Behavioral and biochemical parameters were measured on Day 7 after intraplantar injection of CFA or saline.

RESULTS

Withdrawal thresholds to mechanical stimuli decreased markedly in the CFA-treated paw. In these animals the quantification of proinflammatory mediators in the CSF revealed a significant increase in both PGE2 and TNF-alpha concentrations. All the pharmacological treatments prevented the development of the hyperalgesia as well as the PGE2 increase in the CSF. Conversely, a prevention of the increase in TNF-alpha levels was observed only in rats treated with nimesulide or tramadol and paracetamol in combination.

CONCLUSIONS

Our results demonstrate that peripheral inflammatory hyperalgesia is associated with significant changes of proinflammatory mediators in the CSF. It is important to note, however, that spinal PGE2 and TNF-alpha proved to be differently affected by pharmacological treatments able to fully abolish the hyperalgesia.

Bv8, the amphibian homologue of the mammalian prokineticins, induces a proinflammatory phenotype of mouse macrophages

1.--The small protein Bv8, isolated from the amphibian skin, belongs to a novel family of secreted proteins linked to several biological effects. We describe the expression of Bv8/prokineticins and their receptors in mouse macrophages, and characterize their proinflammatory activities. 2.--The rodent analogue of Bv8, prokineticin-2, is expressed by macrophages, as well as its G-protein-coupled receptor prokineticin receptor (PKR-1 and PKR-2). PKR-1 is expressed more abundantly. 3.-- Bv8 induces potent chemotaxis of macrophages at concentrations as low as 10(-12) M. 4.-- It stimulates lipopolysaccharide-induced production of the proinflammatory cytokines IL-1 and IL-12, reducing that of the anti-inflammatory cytokine IL-10. The effects are observed starting at the very low concentration of 10(-11) M. 5.--Effects on chemotaxis and cytokine are not pertussis-toxin sensitive, but are completely prevented by addition of the phospholipase inhibitor U73122, suggesting a G(q) protein is involved in the Bv8-induced effects. 6.--Studies in PKR-1 knockout mice indicate that all the activities exerted by Bv8 on macrophages are mediated by the PKR-1 receptor. 7.--In conclusion, Bv8 appears to be able to induce the macrophage to migrate and to acquire a proinflammatory phenotype.

Panax ginseng C.A. Mayer G115 modulates pro-inflammatory cytokine production in mice throughout the increase of macrophage toll-like receptor 4 expression during physical stress

The effect of Panax ginseng C.A. Meyer G115 on inflammatory cytokine production and toll-like receptor 4 (TLR4) RNA expression was examined in mice during 4 weeks of swimming stress. Mice were assigned to four groups: (1) control (no exercise); (2) control-G115 (25 mg/kg/day p.o.); (3) stress (kept swimming for 60 min daily); and (4) stress-G115 (25 mg/kg/day p.o. and kept swimming for 60 min daily). Peritoneal macrophages were collected at rest each week. RNA was extracted and processed for real-time PCR. An aliquot of macrophages was lipopolysaccharide (LPS)-stimulated for TNF-alpha and IL-1beta production. Different expression patterns between untreated and treated groups, and between TLR2 and TLR4 were found. High levels of TLR4 expression in the control-G115 group were detectable significantly at the first, and at the second week (P<.01 and P<.001, respectively). In the stress group, TLR4 showed a peak at the first week (P<.001 vs. controls) and then decreased gradually. In the stress-G115 group, the levels of TLR4 expression increased gradually at the second week (P<.001 vs. controls) with a peak at the third week (P<.001). Levels of TLR4 expression at the fourth week had returned to the basal level. Levels of TLR2 expression were not affected by treatment in all groups. A significant increase of LPS-stimulated IL-1beta and TNF-alpha concentrations was present in trained animals with similar patterns of TLR4 expression. These results support the hypothesis that enhancement of the production of pro-inflammatory cytokine can be linked to an increased expression of TLR4 on macrophages. Moreover, G115 increases the expression of TLR4 and the release of cytokines with a different pattern compared to the stressed alone group.

Differential involvement of RelB in morphine-induced modulation of chemotaxis, NO, and cytokine production in murine macrophages and lymphocytes

Acute morphine impairs innate and acquired immunity. The mechanisms involved in immunosuppression have not been well defined yet. The transcription factor NF-kappaB is a central regulator of immunity, and of the NF-kappaB family, RelB is particularly involved in the expression of genes important in immune responses. We investigated the involvement of RelB in morphine-induced immunosuppression in mice deficient for the RelB factor. RelB-/- mice and wild-type (WT) controls were injected s.c. with morphine 20 mg/Kg, and 1 h later, immune parameters were evaluated. Morphine significantly reduced macrophage production of the proinflammatory cytokines IL-1beta, TNF-alpha, and IL-12 in WT animals, and the drug failed to diminish the production of these cytokines in the RelB-/- mice. In contrast, the anti-inflammatory cytokine IL-10 was similarly affected in the two strains. Macrophage NO production was modulated by morphine in WT animals only, and morphine similarly decreased macrophage chemotaxis in the presence or in the absence of RelB. When Th1 and Th2 cytokines were evaluated, we observed a clear morphine-induced reduction of IL-2 and IFN-gamma production by WT splenocytes, whereas no effect of the drug was observed in RelB-/- mice. On the contrary, the production of the Th2 cytokines IL-4 and IL-10 was lessened to the same degree by morphine in WT and RelB-/- mice. In conclusion, our data suggest that RelB is an important target for morphine modulation of proinflammatory and Th1 cytokines. They also indicate that morphine uses multiple intracellular pathways to exert its generalized immunosuppression.

Opioids and the immune system

Opioid compounds such as morphine produce powerful analgesia that is effective in treating various types of pain. In addition to their therapeutic efficacy, opioids can produce several well known adverse events, and, as has recently been recognized, can interfere with the immune response. The immunomodulatory activities of morphine have been characterized in animal and human studies. Morphine can decrease the effectiveness of several functions of both natural and adaptive immunity, and significantly reduces cellular immunity. Indeed, in animal studies morphine is consistently associated with increased morbidity and mortality due to infection and worsening of cancer. However, from several animal studies it emerges that not all opioids induce the same immunosuppressive effects, and evaluating each opioid's profile is important for appropriate analgesic selection. Buprenorphine is a potent opioid that is frequently prescribed for chronic pain. Acute intracerebroventricular administration of buprenorphine has been shown in rats not to affect cellular immune responses, while a statistically significant inhibition of the immune response was observed with morphine. In mouse studies, chronic administration of buprenorphine led to immune parameters important for antimicrobial responses or for anti-tumour surveillance (lymphoproliferation, natural killer (NK)-lymphocyte activity, cytokine production, lymphocyte number) being unaffected. In contrast, levels of these immune markers were significantly reduced when the potent micro-agonist fentanyl was administered, but recovered after longer periods as tolerance developed. Because the intrinsic immunosuppressive activity varies between individual opioids, predicting the outcome on immunity can be difficult. To study this, the effects of morphine, fentanyl and buprenorphine on NK-lymphocyte activity depressed by experimental surgery were examined in rats. Treating animals immediately after surgery with equianalgesic doses of morphine and buprenorphine significantly reduced surgery-induced immunosuppression. However, buprenorphine reverted NK-lymphocyte activity to preoperative levels, while in morphine-treated rats NK-lymphocyte activity was ameliorated, although not completely. In contrast, fentanyl did not prevent immunosuppression induced by surgery. Overall, from several animal studies it emerges that buprenorphine has the more favourable profile, being a potent analgesic devoid of intrinsic immunosuppressive activity.

Opioids and the immune system

Opioid compounds such as morphine produce powerful analgesia that is effective in treating various types of pain. In addition to their therapeutic efficacy, opioids can produce several well known adverse events, and, as has recently been recognized, can interfere with the immune response. The immunomodulatory activities of morphine have been characterized in animal and human studies. Morphine can decrease the effectiveness of several functions of both natural and adaptive immunity, and significantly reduces cellular immunity. Indeed, in animal studies morphine is consistently associated with increased morbidity and mortality due to infection and worsening of cancer. However, from several animal studies it emerges that not all opioids induce the same immunosuppressive effects, and evaluating each opioid's profile is important for appropriate analgesic selection. Buprenorphine is a potent opioid that is frequently prescribed for chronic pain. Acute intracerebroventricular administration of buprenorphine has been shown in rats not to affect cellular immune responses, while a statistically significant inhibition of the immune response was observed with morphine. In mouse studies, chronic administration of buprenorphine led to immune parameters important for antimicrobial responses or for anti-tumour surveillance (lymphoproliferation, natural killer (NK)-lymphocyte activity, cytokine production, lymphocyte number) being unaffected. In contrast, levels of these immune markers were significantly reduced when the potent micro-agonist fentanyl was administered, but recovered after longer periods as tolerance developed. Because the intrinsic immunosuppressive activity varies between individual opioids, predicting the outcome on immunity can be difficult. To study this, the effects of morphine, fentanyl and buprenorphine on NK-lymphocyte activity depressed by experimental surgery were examined in rats. Treating animals immediately after surgery with equianalgesic doses of morphine and buprenorphine significantly reduced surgery-induced immunosuppression. However, buprenorphine reverted NK-lymphocyte activity to preoperative levels, while in morphine-treated rats NK-lymphocyte activity was ameliorated, although not completely. In contrast, fentanyl did not prevent immunosuppression induced by surgery. Overall, from several animal studies it emerges that buprenorphine has the more favourable profile, being a potent analgesic devoid of intrinsic immunosuppressive activity.

The nonpsychoactive component of marijuana cannabidiol modulates chemotaxis and IL-10 and IL-12 production of murine macrophages both in vivo and in vitro

Cannabidiol is the main nonpsychoactive component of marijuana. We examined the ability of in vivo and in vitro cannabidiol to interfere with the production of interleukin (IL)-12 and IL-10 by murine macrophages and to modulate macrophage chemotaxis. Cannabidiol added in vitro to peritoneal macrophages significantly increased IL-12 and decreased IL-10 production. The CB1 and CB2 receptor antagonists prevented this modulation. Macrophages from animals treated with cannabidiol at the dose of 30 mg kg(-1) either orally or i.p. produced higher levels of IL-12 and lower levels of IL-10 in comparison to controls, and the CB receptor antagonists did not prevent these effects. Cannabidiol dose-dependently decreased fMLP-induced chemotaxis of macrophages, and the CB2 receptor antagonist prevented this decrease.

Social factors and individual vulnerability to chronic stress exposure

The stress-response is adaptive in the short-term, but it can be maladaptive if sustained levels of its mediators are chronically maintained. Furthermore, not all individuals exposed to chronic stress will progress to disease. Thus, understanding the causes of individual differences and the consequences of variation in vulnerability is of major importance. The aim of this review is to shed light on this issue by presenting a new naturalistic model of chronic psychosocial stress in male mice. Resident/intruder pairs of mice lived in continuous sensory contact and physically interacted daily. Four categories were identified: Resident Dominant, Resident Subordinate (RS), Intruder Dominant, and Intruder Subordinate. Behavior, autonomic and immune functions, hypothalamic-pituitary-adrenocortical responses, brain cytokine expression and cardiac histology were investigated in stress-exposed mice. Certain stress-induced alterations were present in all mice independent of their social status, while others clearly differentiated dominants from subordinates. RS mice showed a unique profile of alterations suggesting that the loss of relevant resources, such as the territory, is the key factor determining why only certain stress-exposed individuals ultimately show malignancy and psychopathologies.

Cognitive function in young and adult IL (interleukin)-6 deficient mice

Interleukin-6 (IL-6) is a cytokine shown to affect brain function and to be involved in pathological neurodegenerative disorders such as Alzheimer's disease (AD). In the present study we investigated the cognitive function in transgenic mice not expressing IL-6 (IL-6 KO) and in wild type (WT) genotype at 4 and 12 months of age, using a passive avoidance and an eight-arm radial maze tasks. Motor function was quantified using an Animex apparatus. Hippocampal choline acetyltransferase (ChAT) activity was evaluated in both genotypes. No difference was observed in both genotypes for spontaneous motor activity. The mean latency (s) to re-enter the shock box, was similar in both young mutant and WT mice. However, a decreased sensitivity (50%) to scopolamine (1 mg/kg) in mutant compared to WT mice, was obtained. IL-6 KO mice exhibited a facilitation of radial maze learning over 30 days, in terms of a lower number of working memory errors and a higher percentage of animals reaching the criterion as compared with WT genotype tested at both ages. Furthermore, mutant mice, at the age of 12 months, showed a faster acquisition (22 days versus 30 days to reach the criterion). The pattern of arm entry exhibited by IL-6 KO mice showed a robust tendency to enter an adjacent arm at both ages, while WT only at the age of 4 months. ChAT activity was inversely correlated with memory performance. These findings suggest a possible involvement of IL-6 on memory processes, even if the mechanism remains still unclear.

Increased substance P and tumor necrosis factor-alpha level in the paws following formalin injection in rat tail

We previously described a rat model where the injection of formalin in the tail induced a facilitation of the hindpaw withdrawal reflexes (hyperalgesia). In the present work, after injecting formalin in the tail, we measured the levels of pro-nociceptive mediators tumor necrosis factor-alpha (TNF) and substance P (SP) in the rat paws. A significant increase of SP levels was evident in the hindpaw, whereas no changes in SP were observed in the forepaw. Both in the hindpaw and in the forepaw the TNF levels were higher than normal at each stage of measurement. Our results indicate that a prolonged neuronal activation induced by formalin injection is associated with a change in nociceptive and inflammatory mediators in distal sites of the body. The fact that SP levels are changed in the hindpaw but not in the forepaw might point to the activation of a mechanism of retrograde signaling from central synapses to paw afferent nerves.

Psychological, neuroendocrine and immune measures in non spousal carers of disabled elderly in Italy

OBJECTIVES

The purpose of this study was to determine whether psychological well being as well as metabolic, neuroendocrine and immune functions were different in non spousal primary caregivers of disabled elderly than in controls.

SETTING AND DESIGN

We randomly recruited 38 primary family carers of over 65 year old recipients of health home care services and 37 controls stratified according to sex and age.

METHOD

Data were collected on psychological wellbeing (including anxiety, depression and self-perceived quality of life), on neuroendocrine and immune conditions (haemanalysis and metabolic signs, plasma ACTH, cortisol, prolactin, intra-lymphocyte content of beta-endorphins, NK cell activity and number), as well as on the incidence and severity of influenza disease during previous winter.

RESULTS

Caregivers showed greater anxiety, although mean scores did not reach pathological levels. Neither depression nor satisfaction on quality of life did differ significantly, nor differences in haemanalisis and metabolic signs were found, apart from leukocyte and lymphocyte number, which was significantly lower in carers. Plasma levels of ACTH, cortisol and prolactin, the intra-lymphocyte content of beta-endorphins as well as the NK cell number and cytotoxicity did not show significant differences. Incidence and severity of influenza episodes was also similar, whereas the duration of influenza disease showed to be significantly longer.

CONCLUSIONS

Non spousal caregivers of disabled elderly suffer from only slight alterations of psychological, endocrine and immune parameters, and do not respond very differently to influenza disease. This does not support therefore any generic privilege for them in the allocation of public support or respite services.

Behavioral and physiological characterization of male mice under chronic psychosocial stress

Social stress is a major factor in the etiology of several psychopathologies, with individuals greatly differing in vulnerability. The development of appropriate animal models of social stress is, thus, a major challenge of modern bio-medical research. Adult male mice were subjected to a new model of chronic psychosocial stress in which resident/intruder dyads live chronically in sensory contact and physically interact on a daily basis. Four behavioral categories were identified: Resident Dominants (RD), Resident Subordinates (RS), Intruder Dominants (InD), Intruder Subordinates (InS). Here we investigated: behavior during aggressive interactions; gross physiological components of mice metabolism; organ physiology; response to dexamethasone suppression test (DST). RD and InD mice showed persistently high levels of aggression. All four categories of mice showed robust lack of suppression of corticosterone level when challenged with the DST. Although food intake was not altered under chronic stress, body weight decreased in RD and InD mice while increased in InS and, even more so, in RS mice, suggesting an alteration of their metabolic functions. In conclusion, social status and territory ownership were factors determining individual vulnerability to stress exposure. Our model could, thus, be regarded as a valid model to investigate the biological basis of the individual differences in the response to stressful events.

Chronic fentanyl or buprenorphine infusion in the mouse: similar analgesic profile but different effects on immune responses

It is known that morphine has a negative impact on the immune responses. The potent opioids fentanyl and buprenorphine have recently become available as transdermal preparation for the treatment of chronic pain. We analyze the effect of fentanyl and buprenorphine on splenic cellular immune responses in the mouse. The parameters evaluated were lymphoproliferation, natural killer cell activity and interleukin-2 and interferon-gamma production. Drugs were administered acutely at the equianalgesic doses of 0.25 mg/kg for fentanyl and 5 mg/kg for buprenorphine, or delivered continuously with osmotic pumps for 24 h, 3 and 7 days at the rate of 7.5 microg/h per mouse (fentanyl) and 12.5 microg/h per mouse (buprenorphine). After acute administration, a significant decrease of lymphoproliferation is observed in fentanyl-treated animals only. After 24 h of fentanyl administration all the parameters were significantly reduced. After 3 days of fentanyl infusion NK activity had returned to normal values, while all the other parameters were still significantly reduced. In 7 day fentanyl-treated animals immunological tolerance had developed, since no differences with controls were present. In contrast no immune alterations were ever present in buprenorphine-treated animals. No tolerance to the antinociceptive effect of drugs had yet developed. After 1 week of infusion with fentanyl and buprenorphine, new pumps were implanted releasing double amounts of drugs. Neither fentanyl nor buprenorphine-treated animals showed altered immune responses at any time considered. These results indicate that fentanyl and buprenorphine exert different immune effects. Opioid-induced immunosuppression is less relevant in chronic administration than in acute or short-time administration.

Effects of long-term exposure of lemon essential oil odor on behavioral, hormonal and neuronal parameters in male and female rats

Behavioral, hormonal and neuronal responses to prolonged exposure to the volatile components of essential oil (EO) extracted from citrus lemon were investigated in male and female rats. Animals were exposed to the lemon essence for 2 weeks while in their cage. Anxiety was then determined with the elevated plus-maze apparatus while nociception was evaluated with a phasic thermal pain stimulus (plantar test) and with a chemical pain stimulus (formalin test). At the end of the experimental sessions, brain areas were dissected to measure beta-endorphin (beta-EP) concentrations in the hypothalamus and periaqueductal gray matter (PAG). Blood samples were collected to determine corticosterone plasma levels. In both sexes, prolonged EO exposure decreased the time spent in the open arms of the plus-maze apparatus. EO-exposed males and females showed higher thermal nociceptive thresholds than controls when tested with the plantar test apparatus. EO exposure induced female-specific decreases in formalin-induced pain behaviors during the formalin test. beta-EP concentrations in the hypothalamus and PAG were affected by EO. Corticosterone was lower in EO-exposed animals of both sexes than in their controls. These results suggest that long-term exposure to lemon EO can induce significant, at times sex-specific, changes in neuronal circuits involved in anxiety and pain.

Long-term immune-endocrine effects of bereavement: relationships with anxiety levels and mood

Psychological, endocrine and immune parameters were measured over a 6-month period in 14 healthy subjects who underwent an unpredictable acute emotional stress (e.g. sudden death of a loved one) compared with 14 controls who did not. Probands were profoundly stressed as assessed 10 days after bereavement by their scores on the Hamilton Rating Scales of Anxiety and Depression, adrenocorticotropin and cortisol plasma concentrations, and non-suppression in response to dexamethasone. Functional alterations of immune parameters, such as responsiveness of peripheral blood lymphocytes to mitogens, were found 40 days after bereavement. Despite a normal number of circulating lymphocyte subsets, the functional activity of natural killer (NK) cells was markedly reduced at day 40. Changes in the intracellular concentration of beta-endorphin in peripheral blood mononuclear cells correlated with anxiety and depression scores. Controls showed no changes in psychometric, endocrine and immune measures during the 6-month study. Cluster analysis revealed two groups of bereaved subjects with different patterns of immune and endocrine changes: (1) Five subjects, characterized by harm-avoidant temperament and long-lasting dysphoric mood, showed reduced responsiveness of peripheral blood lymphocytes to mitogens, decreased NK cell activity and non-suppression in response to dexamethasone that persisted for 6 months. (2) Nine subjects showed significant changes only during the early phase after bereavement. Our data suggest that the immunological consequences of stress do not simply overlap with psychological and endocrine alterations, and are particularly severe and long-lasting in a subgroup of subjects, indicating the importance of individual variability in the capacity to cope with stress.

Effects of tramadol on synovial fluid concentrations of substance P and interleukin-6 in patients with knee osteoarthritis: comparison with paracetamol

Both the analgesic drugs tramadol and paracetamol are widely used for the symptomatic therapy of osteoarthritis (OA). The aim of this double-blind, randomised study in patients with knee OA was to compare their effects on synovial fluid concentrations of interleukin (IL)-6 and substance P (SP). Moreover, we evaluated plasma and synovial fluid concentrations of tramadol and its active metabolite (O-desmethyl-tramadol, M1) after oral treatment with this drug. Twenty patients were enrolled. A group of 10 patients received tramadol (50 mg three times a day), and another group of 10 patients were treated with paracetamol (500 mg three times a day) for 7 days. Both drugs significantly reduced the intensity of joint pain. The synovial fluid concentrations of SP were significantly reduced only by the treatment with tramadol. In this group of patients, IL-6 synovial fluid concentrations were slightly, but not significantly, decreased. Paracetamol did not significantly change the synovial fluid concentrations of SP and IL-6. After oral administration, a considerable amount of tramadol was measurable in synovial fluid. Both in plasma and synovial fluid the concentrations of M1 were markedly lower than those of tramadol, with a T/M1 ratio of 14.7+/-4.6 and 9.3+/-3.9, respectively. These data demonstrate that the activity of tramadol may involve the modulation of inflammatory mediators. Moreover, they indicate that after oral treatment with tramadol, both the parent drug and its active metabolite can penetrate into synovial fluid.

Chronic psychosocial stress-induced down-regulation of immunity depends upon individual factors

The effect of chronic stress on immune functions is strongly biased by individual factors. Mice were subjected to a new model of chronic psychosocial stress in which four different subcategories of stressed animals may be identified: Resident Dominants (RD), Resident Subordinates (RS), Intruder Dominants (InD), and Intruder Subordinates (InS). After 7 days of stress, mice were immunized with keyhole limpet hemocyanine (KLH). Their immune functions were investigated 14 days later with stress continuing trough. Importantly, RS mice, which are mice losing territory ownership, were the more affected, having lower IgG, proliferation, and IL-2. RD and InD showed lower IgG while InS showed no immune alteration. In conclusion, loss of resources could be a key factor in determining individual vulnerability to stressful events.

Effects of in vitro and in vivo opioids on the production of IL-12 and IL-10 by murine macrophages

We evaluated the ability of the specific micro opioid receptor agonist DAMGO, the kappa-specific agonist U-50488 in vitro, and exogenous opioid morphine administered in vivo both acutely and chronically to modulate IL-12 and IL-10 production by murine peritoneal macrophages. Damgo and U-50488 at the concentrations of 10(-6) and 10(-8) M decreased the production of IL-12 without affecting IL-10. One hour after the acute administration of 5, 10, and 20 mg/kg of morphine a dose-related decrease of both IL-10 and IL-12 levels was present. The pretreatment with naltrexone at doses up to 20 mg/kg did not prevent the decrease of IL-10 and IL-12 induced by morphine. When the drug was administered chronically, a differential development of tolerance to the immune effects was observed. After 3 days of treatment the effect of the acute challenge with 20 mg/kg of morphine on IL-12 was lost. In contrast, morphine-induced inhibition of IL-10 disappeared between 10 and 12 days of treatment, in parallel with tolerance to the antinociceptive effect. These results suggest that opioids modulate macrophage cytokine production. However, the effects exerted by the in vivo administration of morphine are not superimposable onto those induced by the in vitro administration of specific opioid agonists.

Individual housing induces altered immuno-endocrine responses to psychological stress in male mice

Social isolation and lack of social support have deleterious effects on health, thus being regarded as one of the most relevant causes of diseases in human and other mammalian species. However, only few are the studies aimed at evaluating the psychoneuroimmunological functions of individually housed subjects. The present study was designed to understand how the behavior and the physiology of male house mice might be affected by individual housing. We first analyzed whether individual housing of different duration (1-42 days) would result in immuno-endocrine dysfunction (experiment 1). Then we investigated whether housing conditions would affect the reaction to an acute mild psychological stress (experiments 2 and 3). There were three main findings: first, individually housing mice for increasing time periods did not induce any major immuno-endocrine effects compared to a stable sibling group housing. Therefore, prolonged isolation does not seem to dramatically impair mice immuno-endocrine functions. Second, when exposed to a mild acute stress, i.e. forced exposure to a novel environment, isolated mice showed higher basal corticosterone and lower type 1 (IL-2) and type 2 (IL-4) cytokines as well as splenocytes proliferation compared to group housed male mice. Finally, when faced with a free choice between a novel environment and their home cage, individually housed mice showed reduced neophobic responses resulting in increased exploration of the novel environment, thus suggesting a low anxiety profile. Altogether, our findings suggest that individual housing in itself does not change immunocompetence and corticosterone level, but does affect reactivity to a stressor. In fact, individually housed mice showed high behavioral arousal, as well as altered immuno-endocrine parameters, when challenged with mild psychological novelty-stress.

Beta endorphin concentrations in PBMC of patients with different clinical phenotypes of multiple sclerosis

The possible link between the opioid peptide beta endorphin and the heterogeneity of the clinical course of multiple sclerosis (MS) was investigated. Peripheral blood mononuclear cells (PBMC) concentrations of beta endorphin were measured in 50 patients in different phases of MS. Thirty nine patients also underwent post-contrast magnetic resonance imaging of the brain. Among MS forms, the highest beta endorphin concentrations were found in PBMC from patients with relapsing remitting MS and the lowest in patients with the progressive forms. Average beta endorphin concentrations were lower, although not significantly, in patients with than in those without magnetic resonance imaging enhanced lesions. These data suggest that beta endorphin may have a role in the downregulation of the inflammatory process.

The analgesic drug tramadol prevents the effect of surgery on natural killer cell activity and metastatic colonization in rats

Surgery stress has been shown to be associated in rat with decreased natural killer (NK) cell activity and enhancement of tumor metastasis. We have previously shown that the analgesic drug tramadol stimulates NK activity both in the rodent and in the human. In the present study, we analyze, in the rat, tramadol ability to prevent the effect of experimental surgery on NK activity and on the enhancement of metastatic diffusion to the lung of the NK sensitive tumor model MADB106. The administration of tramadol (20 and 40 mg/kg) before and after laparatomy significantly blocked the enhancement of lung metastasis induced by surgery. In contrast, the administration of 10 mg/kg of morphine was not able to modify this enhancement. The modulation of NK activity seemed to play a central role in the effect of tramadol on MADB106 cells. In fact, both doses of tramadol were able to prevent surgery-induced NK activity suppression, while the drug significantly increased NK activity in normal non-operated animals. Morphine, that in normal rats significantly decreased NK cytotoxicity, did not prevent surgery-induced immunosuppression. The good analgesic efficacy of tramadol combined with its intrinsic immunostimulatory properties suggests that this analgesic drug can be particularly indicated in the control of peri-operative pain in cancer patients.

Peripheral blood mononuclear cell beta-endorphin concentration is decreased in chronic fatigue syndrome and fibromyalgia but not in depression: preliminary report

OBJECTIVE

The aim of this study was to examine the possible role of the immune system in the pathophysiology of chronic fatigue syndrome and fibromyalgia syndrome and in the differential diagnosis of depression by investigating changes in peripheral blood mononuclear cell levels of beta-endorphin, an endogenous opioid known to be involved in regulation of the immune system function.

DESIGN

Beta-endorphin concentrations were measured by radioimmunoassay in peripheral blood mononuclear cells from healthy controls (n = 8) and patients with chronic fatigue syndrome (n = 17), fibromyalgia syndrome (n = 5), or depression (n = 10).

RESULTS

Beta-endorphin concentrations were significantly lower in patients with chronic fatigue syndrome or fibromyalgia syndrome than in normal subjects and depressed patients (p <0.001 and p <0.01, respectively). They were significantly higher in depressed patients than in controls (p <0.01).

CONCLUSIONS

Evaluation of peripheral blood mononuclear cell beta-endorphin concentrations could represent a diagnostic tool for chronic fatigue syndrome and fibromyalgia and help with differential diagnosis of these syndromes versus depression. The results obtained are also consistent with the hypothesis that the immune system is activated in both chronic fatigue syndrome and fibromyalgia syndrome.

Differential morphine tolerance development in the modulation of macrophage cytokine production in mice

Morphine has been shown to affect cell-mediated and humoral immune parameters. In this study, we investigated the capacity of in vivo acute and chronic morphine treatment to modulate interleukin (IL)-10 and IL-12 production by LPS and interferon-gamma-stimulated resident and thioglycollate-elicited murine peritoneal macrophages and the development of tolerance to these effects. One hour after the acute administration of 5, 10, and 20 mg/Kg morphine, a dose-related decrease of IL-10 and IL-12 levels was present. The pretreatment with naltrexone at doses up to 20 mg/Kg did not prevent the decrease of IL-10 and IL-12 induced by morphine. When the drug was administered chronically, a differential development of tolerance to the immune effects was observed. After 3 days of treatment, the effect of the acute challenge with 20 mg/Kg morphine on IL-12 was lost. In contrast, morphine-induced inhibition of IL-10 disappeared between 10 and 12 days of treatment, in parallel with tolerance to the antinociceptive effect. These results suggest that morphine treatment affects macrophage cytokine production and that tolerance affects this modulation differently.

Modulation of experimental allergic encephalomyelitis in Lewis rats by administration of a peptide of Fas ligand

The effects of modulation of apoptosis in experimental allergic encephalomyelitis (EAE) in Lewis rats have been investigated using a peptide of the Fas-Ligand protein (FasL-p). The peptide was administered both subcutaneously and intra-cerebro-ventricularly (i.c.v.) after EAE induction. Rats treated subcutaneously with FasL-p showed a worse clinical score as compared to saline treated animals, while i.c.v. treatment with FasL-p did not modify significantly the severity of EAE. Apoptotic lymphomonocytes (identified by TUNEL) infiltrating the brain and the spinal cord were decreased in rats treated i.c.v. with FasL-p. The data suggest that the Fas/Fas-ligand pathway may be modulated by treatments with peptides of Fas-Ligand and that it may be at work within the central nervous system in EAE.

Prevention and treatment of lethal murine endotoxemia by the novel immunomodulatory agent MFP-14

Multifunctional protein 14 (MFP-14) is a ubiquitous protein that inhibits the production of tumor necrosis factor alpha (TNF-alpha) and gamma interferon (IFN-gamma), which are involved in the pathogenesis of sepsis. Here, lipopolysaccharide (LPS)-induced lethality in mice was markedly reduced by MFP-14. The treatment also lowered LPS-induced levels of TNF-alpha and IFN-gamma in the blood.

The opioid antagonist naloxone induces a shift from type 2 to type 1 cytokine pattern in normal and skin-grafted mice

Opioid peptides affect different immune functions. We present evidence that these effects could be mediated by the modulation of Th1/Th2 cytokine production. The acute and chronic treatment with the opioid receptor antagonist naloxone decreased the production of IL-4 by splenocytes of C57BL/6 and Balb/cJ mice, that present a Th1/Th2 dominance, respectively, immunized with the protein antigen KLH. In contrast, IL-2 and IFN-gamma levels were increased after naloxone treatment. These results indicate that naloxone increases Th1 and decreases Th2 cytokine production. Moreover in C57BL/6 mice, naloxone treatment was able to accelerate skin-graft rejection, a Th1-mediated phenomenon, by increasing Th1 cytokine production. The effect of naloxone could be ascribed to the removal of the regulatory effects exerted by endogenous opioid peptides, which could activate Th2 and suppress Th1 cytokines.