Direct cellular immunomodulation produced by diacetylmorphine (heroin) or methadone

Direct effects of heroin and methadone on T cell function

Opioid addiction presents a relevant health challenge, with chronic heroin use linked to detrimental effects on various aspects of physical, mental, and sociological health. Opioid maintenance therapy (OMT), particularly using methadone, is the primary treatment option for heroin addiction. Previous studies using blood samples from current heroin addicts and OMT patients have shown immunomodulatory effects of heroin and methadone on T cell function. However, various additional factors beyond heroin and methadone affect these results, including the consumption of other substances, a stressful lifestyle, comorbid psychological and somatic disorders, as well as additional medications. Therefore, we here investigated the direct effects of heroin and methadone on purified human T cells in vitro. Our results reveal that both, heroin and methadone directly suppress Tcell activation and proliferation. Strikingly, this inhibitory effect was markedly stronger in the presence of methadone, correlating with a decrease in secretion of pro-inflammatory cytokines. While heroin did not interfere with the in vitro differentiation and expansion of regulatory Tcells (Tregs), methadone significantly impaired the proliferation of Tregs. Overall, our findings suggest a direct inhibitory impact of both opioids on effector T cell function in vitro, with methadone additionally interfering with Treg induction and expansion in contrast to heroin.

Immunomodulatory effects of pharmaceutical opioids and antipyretic analgesics: Mechanisms and relevance to infection

Understanding how pharmaceutical opioids and antipyretic analgesics interact with the immune system potentially has major clinical implications for management of patients with infectious diseases and surgical and critical care patients. An electronic search was carried out on MEDLINE, EMBASE, PsycINFO, CENTRAL and the Cochrane library to identify reports describing the immunomodulatory effects of opioid analgesics and antipyretic analgesics, and their effects in infectious diseases. In adaptive immunity, nonsteroidal anti-inflammatory drugs have divergent effects: augmenting cell-mediated immunity but inhibiting humoral immunity. Nonsteroidal anti-inflammatory drugs have demonstrated a beneficial role in Mycobacterium tuberculosis infection and histoplasmosis in animals, and may be plausible adjuvants to antimicrobial agents in these diseases. There is a need to evaluate these findings rigorously in human clinical trials. There is preliminary evidence demonstrating antiviral effects of indomethacin in SARS CoV-2 in vitro; however, uncertainty regarding its clinical benefit in humans needs to be resolved in large clinical trials. Certain opioid analgesics are associated with immunosuppressive effects, with a developing understanding that fentanyl, morphine, methadone and buprenorphine suppress innate immunity, whilst having diverse effects on adaptive immunity. Morphine suppresses key cells of the innate immunity and is associated with greater risk of infection in the postsurgical setting. Efforts are needed to achieve adequate analgesia whilst avoiding suppression of the innate immunity in the immediate postoperative period caused by certain opioids, particularly in cancer surgery.

Effect of morphine and a low dose of ketamine on the T cells of patients with refractory cancer pain in vitro

The combination of morphine and ketamine is considered safe and efficacious in many patients. However, a considerable number of immunomodulatory effects have been reported to be produced by both morphine and ketamine. The aim of the present study was to assess the direct effect of morphine and a low dose of ketamine on the T cells of patients with refractory cancer pain in vitro. Venous blood was obtained from patients with refractory cancer pain and peripheral blood mononuclear cells were isolated using the Ficoll-Hypaque density gradient method. Anti-CD3 beads were used to isolate T cells by positive selection. Subsequently, the T cells were treated with vehicle, 200 ng/ml of morphine or 200 ng/ml of morphine + 100 ng/ml ketamine for 24 h, following which the cells were stimulated with anti-CD3 and anti-CD28. Flow cytometric analysis of CD3⁺ T cells, and interleukin (IL)-2 and interferon (IFN)-γ in the supernatant, reverse transcription-quantitative PCR analysis for the detection of IL-2 and IFN-γ and western blotting for the detection of p65 nuclear factor (NF)-κB were performed. In vitro, the CD4⁺ and CD8⁺ T cell counts, CD4⁺/CD8⁺ ratio, secretion of IL-2 and IFN-γ in the supernatant, mRNA expression levels of IL-2 and IFN-γ and expression of p65 NF-κB were significantly decreased following treatment with morphine and morphine + ketamine, compared with results in the control group (all P<0.05). However, there was no significant difference between treatment with morphine and that with morphine + ketamine. Treatment with morphine + ketamine in vitro decreased the immune functions of patients with refractory cancer pain, although the effect of treatment with morphine and a low dose of ketamine did not differ significantly from that with morphine treatment alone.

Ketamine, as adjuvant analgesics for patients with refractory cancer pain, does affect IL-2/IFN-γ expression of T cells in vitro?: A prospective, randomized, double-blind study

BACKGROUND

Ketamine has been used as an analgesic adjuvant with morphine in the treatment of refractory cancer pain recently. But both morphine and ketamine have been reported to produce a number of immunomodulatory effects. The current study was performed to assess whether the concentration of ketamine, as adjuvant analgesics for patient with refractory cancer pain, was related to its effect on T cells interleukin-2 (IL-2)/interferon-γ (IFN-γ) expression in vitro.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from venous blood of patients with refractory cancer pain over a Ficoll-Hypaque density gradient. T cells were isolated from by positive selection using anti-CD3 beads. T cells were then treated with vehicle (C group), morphine (200 ng/mL, M group), morphine (200 ng/mL), and different dose of ketamine (100, 200, 1000 ng/mL; MK1, MK5, MK10 group) for 24 hours before stimulation with anti-CD3 and anti-CD28. Then supernatant IL-2 and IFN-γ protein analysis, quantitative reverse transcription polymerase chain reaction (RT-PCR) for IL-2 and IFN-γ were done.

RESULTS

There were no significant difference of supernatant IL-2 and IFN-γ among C group, M group, and MK1 group, but the mRNA of M group and MK1 group were decreased compared with C group (P < .05). Compared with C group, both of the supernatant protein and the mRNA of MK5 group and MK10 group were all significantly decreased (P < .01). Compared with M group, both of the supernatant protein and the mRNA of MK5 group and MK10 group were all decreased (P < .05), while supernatant IL-2 and the mRNA of MK10 group were significantly decreased (P < .01).

CONCLUSION

In conclusion, we confirmed that just as morphine, ketamine dose-dependently suppressed IL-2 and IFN-γ of activated T lymphocyte of patients with refractory cancer pain in vitro, but the inhibitory action of low dose ketamine could be neglected.

Drugs of abuse and addiction: A slippery slope toward liver injury

Substances of abuse induce alteration in neurobehavioral symptoms, which can lead to simultaneous exacerbation of liver injury. The biochemical changes of liver are significantly observed in the abused group of people using illicit drugs or drugs that are abused. A huge amount of work has been carried out by scientists for validation experiments using animal models to assess hepatotoxicity in cases of drugs of abuse. The risk of hepatotoxicity from these psychostimulants has been determined by different research groups. Hepatotoxicity of these drugs has been recently highlighted and isolated case reports always have been documented in relation to misuse of the drugs. These drugs induce liver toxicity on acute or chronic dose dependent process, which ultimately lead to liver damage, acute fatty infiltration, cholestatic jaundice, liver granulomas, hepatitis, liver cirrhosis etc. Considering the importance of drug-induced hepatotoxicity as a major cause of liver damage, this review emphasizes on various drugs of abuse and addiction which induce hepatotoxicity along with their mechanism of liver damage in clinical aspect as well as in vitro and in vivo approach. However, the mechanisms of drug-induced hepatotoxicity is dependent on reactive metabolite formation via metabolism, modification of covalent bonding between cellular components with drug and its metabolites, reactive oxygen species generation inside and outside of hepatocytes, activation of signal transduction pathways that alter cell death or survival mechanism, and cellular mitochondrial damage, which leads to alteration in ATP generation have been notified here. Moreover, how the cytokines are modulated by these drugs has been mentioned here.

Effects of opioids on immunologic parameters that are relevant to anti-tumour immune potential in patients with cancer: a systematic literature review

Background:

The immune system has a central role in controlling cancer, and factors that influence protective antitumour immunity could therefore have a significant impact on the course of malignant disease. Opioids are essential for the management of cancer pain, and preclinical studies indicate that opioids have the potential to influence these tumour immune surveillance mechanisms. The aim of this systematic literature review is to evaluate the clinical effects of opioids on the immune system of patients with cancer.

Methods:

A systematic search of Ovid MEDLINE (PubMed) and Embase, Cochrane database and Web of Knowledge for clinical studies, which evaluated the effects of opioids on the immune system in patients with cancer, was performed.

Results:

Five human studies, which have assessed the effects of opioids on the immune system in patients with cancer, were identified. Although all of these evaluated the effect of morphine on immunologic end points in patients with cancer, none measured the clinical effects.

Conclusions:

Evidence from preclinical, healthy volunteer and surgical models suggests that different opioids variably influence protective anti-tumour immunity; however, actual data derived from cancer populations are inconclusive and definitive recommendations cannot be made. Appropriately designed and powered studies assessing clinical outcomes of opioid use in people with cancer are therefore required to inform oncologists and others involved in cancer care about the rational use of opioids in this patient group.

μ opioid receptor agonist-selective regulation of interleukin-4 in T lymphocytes

Opioids are irreplaceable for the treatment of severe pain. However, opioid-induced immunomodulation affects therapies. Here we report that treatment of human T lymphocytes with the opioids fentanyl, methadone, loperamide and beta-endorphin resulted in a strong induction of the cytokine interleukin-4. In contrast, morphine and buprenorphine induced markedly and significantly lower levels of interleukin-4 mRNA and protein. These findings suggest agonist-biased μ opioid receptor signaling in T cells. In the future, better knowledge about agonist-specific immunomodulatory effects of opioids offers the possibility to select drugs for a therapy with more favorable and/or less detrimental side effects in immune cells.

Expression and functions of μ-opioid receptors and cannabinoid receptors type 1 in T lymphocytes

Opioids and cannabinoids modulate T lymphocyte functions. Many effects of the drugs are mediated by μ-opioid receptor and cannabinoid receptor type 1 (CB1), respectively. These two receptors are strikingly similar with respect to their expression in T cells and the mechanisms by which they mediate modulation of T cell activity. Thus, μ-opioid receptors and CB1 not expressed in resting primary human and Jurkat T cells. However, in response to the cytokine IL-4, the epigenetic modifiers 5-aza-2'-deoxycytidine and trichostatin A, and activation of T cells, functional μ-opioid receptors and CB1 are induced. The induced receptors mediate inhibition of T cell signaling and, thereby, IL-2 production, a hallmark of activated T cells. Although coupled to inhibitory G proteins, μ-opioid receptors and CB1 produce a remarkable increase in cAMP levels in T cells stimulated with opioids and cannabinoids, which is a key mechanism for the inhibition of T cell signaling.

Opioid maintenance therapy restores CD4+ T cell function by normalizing CD4+CD25(high) regulatory T cell frequencies in heroin user

There is an increasing body of evidence that heroin addiction is associated with severe alterations in immune function, which might contribute to an increased risk to contract infectious diseases like hepatitis B and C or HIV. However, the impact of heroin consumption on the CD4(+) T cell compartment is not well understood. Therefore, we analyzed the frequency and functional phenotype of CD4(+) T cells as well as immune-suppressive CD4(+)CD25(high) regulatory T cells (Tregs) isolated from the peripheral blood of opiate addicts currently abusing heroin (n=27) in comparison to healthy controls (n=25) and opiate addicts currently in opioid maintenance treatment (OMT; n=27). Interestingly, we detected a significant increase in the percentage of CD4(+)CD25(high) Tregs in the peripheral blood of heroin addicted patients in contrast to patients in OMT. The proliferative response of CD4(+) T cells upon stimulation with anti-CD3 and anti-CD28 antibodies was significantly decreased in heroin users, but could be restored by depletion of CD25(high) regulatory T cells from CD4(+) T cells to similar values as observed from healthy controls and patients in OMT. These results suggest that impaired immune responses observed in heroin users are related to the expansion of CD4(+)CD25(high) Tregs and more importantly, can be restored by OMT.

Interplaying factors that effect multiple sclerosis causation and sustenance

The author hypothesized that multiple sclerosis (MS) is a humoral autoimmune disease, caused by faulty interplay between myelin-specific, dimeric IgE, specifically competing non-IgE antibodies and IgE-triggered degranulating mast cells. The principal fault was believed to be insufficient quantity of protective, specific non-IgE antibodies. Also conjectured was the possibility of an unexpected and adverse immune suppression caused by none-MS pharmaceuticals being consumed by patients for their MS or for other conditions. To test both hypotheses, a mimotopic, peptide antigen-based, serum immunoassay was developed to measure dimer-bound IgE excess among MS patients, wherein the IgE specifically complexes with two or more myelin surface epitopes at an interval of 40–100 Angstroms, a separation critical for mast cell degranulation and cell damaging effect. MS test sensitivity and specificity, when analyzing five previously untreated patients for dimeric IgE presence, was 100%. In direct comparison, twenty age- and gender-matched female and male control subjects were test negative. Analysis of 35 multiple sclerosis patients, who were concomitantly being treated with potentially immunosuppressive pharmaceuticals, appeared to show the substances' negative effect upon MS causation, progression, or specific immunoassay performance. Therefore, MS is likely an autoimmune disease caused by IgE-mediated mast cell degranulation possibly in conjunction with immunosuppressive agents.

Opioid drug abuse and modulation of immune function: consequences in the susceptibility to opportunistic infections

Infection rate among intravenous drug users (IDU) is higher than the general public, and is the major cause of morbidity and hospitalization in the IDU population. Epidemiologic studies provide data on increased prevalence of opportunistic bacterial infections such as TB and pneumonia, and viral infections such as HIV-1 and hepatitis in the IDU population. An important component in the intravenous drug abuse population and in patients receiving medically indicated chronic opioid treatment is opioid withdrawal. Data on bacterial virulence in the context of opioid withdrawal suggest that mice undergoing withdrawal had shortened survival and increased bacterial load in response to Salmonella infection. As the body of evidence in support of opioid dependency and its immunosuppressive effects is growing, it is imperative to understand the mechanisms by which opioids exert these effects and identify the populations at risk that would benefit the most from the interventions to counteract opioid immunosuppressive effects. Thus, it is important to refine the existing animal model to closely match human conditions and to cross-validate these findings through carefully controlled human studies. Better understanding of the mechanisms will facilitate the search for new therapeutic modalities to counteract adverse effects including increased infection rates. This review will summarize the effects of morphine on innate and adaptive immunity, identify the role of the mu opioid receptor in these functions and the signal transduction activated in the process. The role of opioid withdrawal in immunosuppression and the clinical relevance of these findings will also be discussed.

Exploring the neuroimmunopharmacology of opioids: an integrative review of mechanisms of central immune signaling and their implications for opioid analgesia

Vastly stimulated by the discovery of opioid receptors in the early 1970s, preclinical and clinical research was directed at the study of stereoselective neuronal actions of opioids, especially those played in their crucial analgesic role. However, during the past decade, a new appreciation of the non-neuronal actions of opioids has emerged from preclinical research, with specific appreciation for the nonclassic and nonstereoselective sites of action. Opioid activity at Toll-like receptors, newly recognized innate immune pattern recognition receptors, adds substantially to this unfolding story. It is now apparent from molecular and rodent data that these newly identified signaling events significantly modify the pharmacodynamics of opioids by eliciting proinflammatory reactivity from glia, the immunocompetent cells of the central nervous system. These central immune signaling events, including the release of cytokines and chemokines and the associated disruption of glutamate homeostasis, cause elevated neuronal excitability, which subsequently decreases opioid analgesic efficacy and leads to heightened pain states. This review will examine the current preclinical literature of opioid-induced central immune signaling mediated by classic and nonclassic opioid receptors. A unification of the preclinical pharmacology, neuroscience, and immunology of opioids now provides new insights into common mechanisms of chronic pain, naive tolerance, analgesic tolerance, opioid-induced hyperalgesia, and allodynia. Novel pharmacological targets for future drug development are discussed in the hope that disease-modifying chronic pain treatments arising from the appreciation of opioid-induced central immune signaling may become practical.

Pulmonary complications related to heroin overdose and some changes in immune reactivity

To examine the clinical spectrum of complications in pulmonary system and changes of some parameters of humoral and cell mediated immunity related to heroin overdose. The study includes 16 patients who are long-term heroin abusers with acute heroin and mixed with other psychoactive drugs intoxications with an average age of 21,5 ± 5.04 years (12 men and 4 woman). All patients were hospitalized in the Clinic of Toxicology, MHATEM “N.I.Pirogov”, Sofia. We have used clinical, clinico-laboratory, immunological, chimicotoxicological, instrumental methods. In severe intoxications with heroin and other psychoactive drugs, we observed pulmonary system complications, i.e. pneumonia, aspiration of gastric contents, noncardiogenic pulmonary edema (NCPE) and acute respiratory distress syndrome (ARDS.). Of the 16 patients in our study, 3 patients died due to complications. Some changes in the immune reactivity observed in the study were (1) statistically significant lower mean levels of IgG and (2) tendency to lower mean levels of IgA, IgM and complement components — C3 in the studied patients in comparison with the values in healthy people. The changes were more demonstrative in the group with pulmonary complications compared to the group without pulmonary complications. We observed that the CD4 lymphocytes were significantly less in the studied patients; in addition, a lower level of CD56-bearing lymphocytes (natural killer /NK/ cells) was observed in comparison to healthy controls. The results show that the mixture of acute heroin with other psychoactive drugs leads to complications in the pulmonary system and changes of some parameters of cell-mediated and humoral immunity.

Stress-opioid interactions: a comparison of morphine and methadone

The utility of methadone and morphine for analgesia and of methadone for substitution therapy for heroin addiction is a consequence of these drugs acting as opioid receptor agonists.We compared the cataleptogenic and antinociceptive effects of single subcutaneous doses of methadone hydrochloride (1-4 mg/kg) and morphine sulfate (2.5-10 mg/kg) using catalepsy and hot-plate tests, and examined the effects of the highest doses of the drugs on Fos protein expression in selected brain regions in male Sprague-Dawley rats. Methadone had greater cataleptogenic and analgesic potency than morphine. Fos immunohistochemistry revealed substantial effects on the Fos response of both the stress induced by the experimental procedures and of the drug exposure itself. There were three response patterns identified: 1) drug exposure, but not stress, significantly elevated Fos-positive cell counts in the caudate-putamen; 2) stress alone and stress combined with drug exposure similarly elevated Fos-positive cell counts in the nucleus accumbens and cingulate cortex; and 3) methadone and morphine (to a lesser extent) counteracted the stimulatory effect of nonpharmacological stressors on Fos protein expression in the somatosensory cortex barrel field, and Fos-positive cell counts in this region correlated negatively with both the duration of catalepsy and the latency time in the hot-plate test. The overlap between brain regions reacting to nonpharmacological stressors and those responding to exogenous opioids suggests that stress contributes to opioid-induced neuronal activation.

[Could anaesthesia, analgesia and sympathetic modulation affect neoplasic recurrence after surgery? A systematic review centred over the modulation of natural killer cells activity]

OBJECTIVE

The Natural Killer cells (NK) are an important part of non-specific cellular-mediated and antitumoral immunity. The goal of this review is to recapitulate data published over NK activity during the perioperative period and the influence of anaesthesia, analgesia and modulation of sympathetic system.

DATA SOURCES

Pubmed/Medline database.

STUDY SELECTION AND DATA EXTRACTION

Keywords-based selection, without limit of date: fundamental studies, randomized controlled trials and non-randomized comparative studies.

DATA SYNTHESIS

In human as in animal studies, an important correlation exists between NK activity and prognosis linked to the development of metastasis. The great depression of this cytotoxicity during the perioperative period could be able to compromise host defenses. The influence of anaesthetics and analgesics is important. The effects of the opioids, the agonists and the antagonists of the sympathetic nervous system, the prostaglandins, the NSAIDs, the ketamine, the hypnotics and the locoregional anaesthesia are systematically reviewed. The limits of experimental model presented are covered.

CONCLUSION

The effects of anaesthetic/analgesic drugs and techniques, the consequences of sympathomodulation on NK activity are numerous and sometimes opposite. It is important for the anaesthesiologist to keep in mind that the long term consequences of his techniques on the patients' outcome must be clarified.

Circadian alteration in neurobiology during 30 days of abstinence in heroin users

BACKGROUND

Previous studies have shown that individuals withdrawn from chronic opiate administration undergo substantial elevations of cortisol levels with blunted corticotropin (ACTH) rhythms and that these changes persist beyond the 7-10 days of acute withdrawal symptoms. However, there are no published studies of changes in expression of clock genes or of other neuropeptides related to circadian-rhythm regulation, which may influence relapse susceptibility.

METHODS

Blood samples were collected from 8 healthy control subjects and 16 heroin addicts during pharmacologically unassisted withdrawal on the 3rd, 10th, and 30th days of abstinence at 3-hour intervals for 24 hours. Outcome measures were the relative expression of clock gene mRNA (hperiod1, hperiod2, hclock) and the levels of serum cortisol, plasma ACTH, beta-endorphin (beta-EP), leptin, neuropeptide Y, interleukin-2 (IL-2), and tumor necrosis factor (TNF) in these subjects.

RESULTS

Compared with healthy volunteers, abstinent addicts showed disruptions in diurnal rhythms of hPER1 and hPER2 mRNA expression, along with disruptions in diurnal rhythms of cortisol, ACTH, beta-endorphin, leptin, and IL-2 release. Several of these disruptions (hPER1, hPER2, ACTH, beta-endorphin, and IL-2) persisted for the 30-day testing period, as did elevation of 24-hour levels of cortisol and decreases in 24-hour IL-2 and TNF levels.

CONCLUSIONS

These prolonged neurobiological changes may play a role in protracted opiate withdrawal symptoms and contribute to relapse vulnerability.

Level of liver fibrosis and immune status of mice of different age after heroin treatment and long abstinence

Young and middle-aged CBA mice were injected with "street" heroin in increasing doses for 14 days. Volume density of perisinusoid argirophilic fibers increased in both age groups (the increase being more pronounced in middle-aged mice), while the levels of spontaneous, LPS- and ConA-stimulated splenocyte proliferation decreased in young mice. Six months after heroin discontinuation further progress of liver fibrosis was observed in young mice.

Characterisation of the in vitro modulation of splenocyte proliferation by non-4,5-epoxymorphinan opioids

Opioids, such as morphine, can directly alter immune function via receptors expressed on immunocompetent cells. However, several studies have questioned the classical opioid nature of this change in immune response. Therefore, it is unclear how opioids that are not from the same structural class as morphine (4,5-epoxymorphinan), will modulate the immune system, if they do not behave in a classical opioid manner. Therefore, the aim of this study was to investigate the in vitro modulatory effects of a range of non-4,5-epoxymorphinan opioids on splenocyte proliferation and compare the response characteristics to their central opioid characteristics. The modulation of concanavalin A stimulated mouse splenocyte proliferation by non-4,5-epoxymorphinan opioids resulted in three types of responses: an inhibitory concentration-response curve (e.g. methadone, inhibitory EC(50)=79.4 microM), an inverted bell shaped curve (e.g. fentanyl, inhibitory EC(50)=0.06 microM) and an induction concentration response curve (e.g. nor-binaltorphimine, induction EC(50)=0.16 microM). Non-stereoselectivity, naloxone-insensitivity, naloxone-sensitivity and non-classical opioid rank order of effect were all observed. These data support the non-classical opioid nature of direct opioid modulation of splenocyte proliferation.

(S)-(+)-methadone is more immunosuppressive than the potent analgesic (R)-(--)-methadone

Methadone is a widely used synthetic opioid which is administered as a racemic mixture of (R)-(--)- and (S)-(+)-enantiomers, with only (R)-(--)-methadone possessing mu opioid receptor agonist activity. Methadone inhibits numerous immune functions in vitro at concentrations above 10 microM in a nonstereoselective and naloxone-insensitive fashion, suggesting the presence of nonclassical opioid receptors on immune cells. No in vivo data on the effects of methadone's enantiomers on immune function are available. Therefore, the stereoselectivity of methadone's analgesia (hot plate latency) in vivo and immune suppression ex vivo (splenocyte proliferation) was investigated in groups of Balb/c mice. Significant analgesia was observed in animals that received racemic methadone (P=0.0012, 52% MPE) and (R)-(--)-methadone (P=0.0002, 70% MPE) when compared to saline-treated controls, while (S)-(+)-methadone was devoid of any such effect (-4% MPE). In vivo (R)-(--)- and racemic methadone caused significant inhibition (P<0.001, greater than -70%) of basal proliferation compared to saline control. In stark contrast to analgesia, in vivo (S)-(+)-methadone caused significantly greater inhibition of basal proliferation (P<0.001, -130%) than (R)-(--)- and racemic methadone. The immune suppression caused by methadone is not purely a classical opioid response but involves nonclassical opioid receptors located at the central level, which have yet to be characterised. Moreover, the dose at which immune suppression occurred could be achieved clinically.

Immune parameters and morbidity in hard drug and human immunodeficiency virus-exposed but uninfected infants

OBJECTIVE

To examine the association of maternal hard drug use (injection drugs, cocaine, and opiates) on lymphocyte subsets and clinical morbidity in uninfected infants who are born to human immunodeficiency virus-infected mothers who were enrolled in the Women and Infants Transmission Study (1990-2000).

METHODS

Maternal hard drug use was identified by self-report and/or urine toxicology. Infant evaluations occurred at birth and at 1, 2, 4, 6, 9, 12, 18, and 24 months of age.

RESULTS

A total of 401 (28%) of the 1436 uninfected infants were born to drug-using mothers. Maternal CD4 lymphocyte percentage and RNA at delivery were not significantly different between drug users and nonusers. Infants who were born to drug-using mothers had lower mean gestational age (37.8 vs 38.5 weeks) and birth weight (2.9 vs 3.1 kg). Infants with intrauterine drug exposure had lower CD4 lymphocyte percentage over the first 4 months of life after adjusting for covariates and higher natural killer lymphocyte percentage. When the analysis was stratified by time period of entry, the incidence of clinical events was not different between infants who were born to drug users versus nonusers.

CONCLUSION

Maternal hard drug use is associated with immunologic changes in infants early in life, although these changes did not seem to be associated with increased risk of infections.

Microbial infections, immunomodulation, and drugs of abuse

The use of recreational drugs of abuse has generated serious health concerns. There is a long-recognized relationship between addictive drugs and increased levels of infections. Studies of the mechanisms of actions of these drugs became more urgent with the advent of AIDS and its correlation with abused substances. The nature and mechanisms of immunomodulation by marijuana, opiates, cocaine, nicotine, and alcohol are described in this review. Recent studies of the effects of opiates or marijuana on the immune system have demonstrated that they are receptor mediated, occurring both directly via specific receptors on immune cells and indirectly through similar receptors on cells of the nervous system. Findings are also discussed that demonstrate that cocaine and nicotine have similar immunomodulatory effects, which are also apparently receptor mediated. Finally, the nature and mechanisms of immunomodulation by alcohol are described. Although no specific alcohol receptors have been identified, it is widely recognized that alcohol enhances susceptibility to opportunistic microbes. The review covers recent studies of the effects of these drugs on immunity and on increased susceptibility to infectious diseases, including AIDS.

Diacetylmorphine degradation to 6-monoacetylmorphine and morphine in cell culture: implications for in vitro studies

Diacetylmorphine deacetylates rapidly to 6-monoacetylmorphine and then to morphine. The immunomodulatory effects of diacetylmorphine are under investigation by several groups utilising various methods including in vitro cell culture; however, diacetylmorphine stability under these conditions is unknown. The aim of this study was to quantify diacetylmorphine degradation under cell culture conditions and to determine the mechanism by which this occurs. Diacetylmorphine degradation in a mouse splenocyte mitogenesis assay was investigated. Morphine and 6-monoacetylmorphine were quantified using HPLC with UV detection. After 6 h, approximately 73% of diacetylmorphine had been hydrolysed in the presence of cells. The half-life of diacetylmorphine was 1.4 h in cell media alone and 1.2-2.2 h in incubations containing cells, while the half-life of 6-monoacetylmorphine was 3.1 h in cell media alone and 0.99-1.2 h in incubations containing cells. 6-Monoacetylmorphine and morphine formation were found to be dependent on incubation time and diacetylmorphine concentration, and were not dependent on esterase activity, mitogen concentration, presence of erythrocytes and cell media evaporation. Only morphine formation was dependent on lymphocyte concentration. 6-Monoacetylmorphine formation was independent of cells and appeared to be due to the conditions of the cell culture (pH and temperature), while morphine formation was dependent to a greater extent on cells, but independent of esterase activity. The study highlights the limitations of conclusions made in previous studies which have not recognised diacetylmorphine instability.

Opioids, immunology, and host defenses of intravenous drug abusers

Overall, it is apparent that opioids do affect host defense mechanisms. Heroin users present with an altered and functionally impaired immune system and have a higher prevalence of infectious diseases than do nonaddicts. Individuals exposed to opioid treatment for pain management during surgical procedures or maintained on oral methadone for treatment of drug addiction show either no effect or a suppressed immune system, depending on dosage and, in the case of methadone-maintained patients, duration of drug treatment. Confounding factors in these studies undermine definitive conclusions about the mechanisms by which opioids induce their immunomodulatory effects. Animal models have provided the means by which investigators can study the effects of opioids in a complex, biologic system that is easily manipulated and controlled. Findings from these studies have confirmed human data associating a pathogenic susceptibility with opioid use. Animal models have shown the complexity of this association. Interaction of the CNS, the autonomic nervous system, and the HPA axis is required for the varied effects of opioids on the immune system. By implication, exogenous opioids may be mimicking pathways by which endogenous opioids are involved in regulating immune defenses. To minimize the increased incidence of infectious diseases in heroin users and individuals clinically exposed to opioids, it will be important to determine the individual and collective effects of the opioid-induced activation of these pathways and the consequences of that activation to the immune system.

Opioid receptors on white blood cells: effect of HIV infection and methadone treatment

Opioid receptors (OR) are involved in many physiological and pathological immune functions. During recent years, the treatment of opiate addiction with methadone in HIV-positive and HIV-negative patients has become widely accepted. However, little is known on the occurrence and course of OR on lymphocytes of these individuals. The objective of the study was to detect and quantify OR on peripheral white blood cells (WBC) by fluorescence-activated cell sorting using polyclonal antibodies and reverse transcriptase polymerase chain reaction, and to assess the influence of HIV infection and methadone treatment. We compared OR levels in 80 HIV-positive homosexuals, 18 HIV-positive intravenous drug users (IVDU) treated with methadone, 18 HIV-negative IVDU receiving methadone and 25 healthy controls. HIV infection was shown to decrease the amount of OR on WBC, especially of the delta-subtype on lymphocytes and granulocytes. The decrease correlated with the duration of HIV-infection (P<0.01), and inversely with the HIV viral load (P<0.01). In contrast, chronic methadone administration led to a significant increase of OR exclusively in HIV-negative IVDU. In particular the delta-OR was increased by 31-, 62- and 42-fold on lymphocytes, monocytes and granulocytes of HIV-negative patients (each P<0.005), respectively, which was not observed in HIV-positive IVDU. Therefore, HIV seems to reduce OR particularly on lymphocytes and granulocytes regardless of the mode of HIV transmission. The quantification of OR on immune cells may help to elucidate the effects of opioid analogues in health and drug addiction.

Self-administration of heroin produces alterations in the expression of inducible nitric oxide synthase

Nitric oxide plays a critical role in the immune response, and our studies have shown that heroin induces a reduction in the expression of iNOS, the enzyme responsible for nitric oxide production. The present study evaluated the effect of heroin self-administration on iNOS expression using a three-group design. Group one (self-administration) was trained to press a lever for i.v. administration of heroin. Group two (yoked heroin) received a simultaneous equivalent infusion of heroin determined by the responses of a 'partner' animal in the first group. A third group (yoked saline) also was yoked to the first group, but received i.v. injections of saline. Immediately following the last session, all rats received an injection of lipopolysaccharide (LPS) to induce iNOS expression. About 6 h after the injection of LPS, iNOS mRNA and protein expression were determined in spleen, lung, and liver. Additionally, the accumulation of plasma nitrite/nitrate, the more stable end products of nitric oxide degradation were measured. Although there was not a consistent difference between the self-administering and yoked-heroin animals, the results show that rats will self-administer a sufficient amount of heroin to induce a pronounced, widespread reduction in the expression of iNOS.

The effects of morphine on cell proliferation

There is increasing evidence that endogenous opioid peptides ("enkephalins") and other neurotransmitters have widespread, receptor-mediated roles as growth regulators in non-neuronal cells and tissues. For example, it is now believed that enkephalins produced in placental trophoblast giant cells have multiple roles in supporting embryo growth, and in maternal adaptation to pregnancy. Since plant and synthetic narcotics (e.g., morphine) bind to the same receptors, the questions immediately arise: Do narcotics also have actions as growth regulators? If so, do these actions have physiological significance in addicts? Recent work on the first of these questions is covered in this review. While the greatest volume of research has been focused on the proliferative effects of narcotics for cells of the immune system, the roles of opioid peptides and narcotics on the growth of a variety of other cells has come under study recently.

Antipneumolysin antibody titers in HIV-seropositive injection drug users before and after pneumococcal bacteremia

Lower baseline antipneumolysin antibody (alpha-PLY) levels have been found in populations with a higher incidence of pneumococcal infections. To determine whether predisease alpha-PLY titer is associated with invasive pneumococcal disease in HIV-seropositive injection drug users (IDU), we utilized a prospective cohort of IDU in Baltimore to compare alpha-PLY titers before bacteremia in 28 HIV- seropositive IDU cases with alpha-PLY titers in 56 matched (CD4 and seroconversion date) HIV-seropositive IDU control subjects and 28 matched (calendar time) HIV-seronegative IDU control subjects remaining free of pneumococcal disease. We also compared the postinfection fold-rise of alpha-PLY titers in cases relative to the change in alpha-PLY titers in control subjects during the same interval; alpha-PLY titers were measured using quantitative ELISA, and functional activity was assessed using antihemolysin assays. Predisease alpha-PLY titer did not differ between cases (66 units) and HIV-seropositive control subjects (70 units, p = 0.56) or HIV-seronegative control subjects (80 units, p = 0.10). There was a significant difference in fold-rise of alpha-PLY titers postdisease between cases (1.18) and HIV-seronegative control subjects (0.76), p = 0.03. Baseline alpha-PLY titers do not differ significantly between HIV-seropositive IDU who develop pneumococcal bacteremia from HIV-seropositive and HIV-seronegative IDU control subjects remaining free of severe pneumococcal disease.

Pharmacokinetics and cytokine production in heroin and morphine-treated mice

The parallelism between serum levels of heroin and morphine (M) metabolites and the production of interleukin-1beta (IL-1beta), interleukin-2 (IL-2), interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-alpha), transforming growth factor-beta1 (TGF-beta1), and interferon-gamma (IFN-gamma) from murine splenocyte cultures following s.c. injection with 20 mg/kg heroin or M in C57/BL mice is described. The pharmacokinetic profiles of M and inactive morphine-3-glucuronide (M3G) in morphine-treated mice nearly overlapped those in heroin-treated mice, with the only difference being the presence of 6-monoacetylmorphine (AM) in profiles of the latter group. Heroin and M significantly increased production of IL-1beta, IL-2, TNF-alpha and IFN-gamma at 3, 20 and 40 min from treatment, peaking at 20 min, though the effect was very brief. At 24 h production was greatly inhibited, and this depressive effect lasted longer than the stimulatory effect. At 48 h only a partial recovery was observed. Heroin and M also had a highly stimulatory effect on the release of anti-inflammatory cytokines such as TGF-beta1 and IL-10, though this effect was observed after 120 min, peaking at 24 h and then somewhat decreasing at 48 h. This study demonstrates that the more rapid and pronounced immune response to heroin treatment was due to the presence of AM. Both heroin and M produced a biphasic effect on cytokine production: the central opioid or non-opioid receptors are involved in exogenous opiod-induced stimulatory effects, whereas peripheral opioid or non-opioid receptors are involved in depressive effects. Deficient or excess expression of these key mediators may predispose the host to aberrant defence mechanisms.

Phenotypic and functional assessments of immune status in the rat spleen following acute heroin treatment

Heroin use is associated with an increased incidence of several types of infections, including HIV. Yet few studies have assessed whether heroin produces pharmacological alterations of immune status that might contribute to the increased rate of infections amongst heroin users. The present study investigated whether a single administration of heroin to rats produces dose-dependent alterations in functional measures of immune status and in the distribution of leukocyte subsets in the spleen. The results showed that heroin produces a dose-dependent, naltrexone-reversible suppression of the concanavalin A-stimulated proliferation of T cells, lipopolysaccharide-stimulated proliferation of B cells, production of interferon-gamma and cytotoxicity of natural killer (NK) cells in the spleen. Heroin's suppressive effect on NK cell activity results in part from a heroin-induced decrease in the relative number of NKR-P1A(hi) CD3- NK cells in the spleen. Heroin also decreases the percent of a splenic granulocyte subset, the CD11b/c+ HIS48(hi) cells, whose function currently is unknown. In contrast, heroin does not alter relative numbers of CD4+ CD3+ T cells, CD8+ CD3+ T cells, CD45+ B cells, NKR-P1A(lo) CD3+ T cells, CD11b/c+ ED1+ (or CD11b/c+ HIS48-) monocytes/macrophages or CD11b/c+ ED1- (or CD11b/c+ HIS48+) total granulocytes in the spleen. Collectively, these findings demonstrate that heroin produces pharmacological effects on functional and phenotypic measures of immune status.

Opioid modulation of immune responses: effects on phagocyte and lymphoid cell populations

The literature describing effects of morphine on cells of the immune system points to the clear conclusion that morphine given in vivo suppresses a variety of immune responses that involve the major cell types in the immune system, including natural killer (NK) cells, T cells, B cells, macrophages and polymorphonuclear leukocytes (PMNs). Depression of NK cell activity has been reported in humans, monkeys and rodents. Similarly, responses of T cells are depressed by morphine, as assessed by inhibition of induction of delayed-type hypersensitivity reactions and cytotoxic T-cell activity, modulation of T-cell antigen expression, and depression of responses to T-cell mitogens. Effects on T cells have been reported in humans, monkeys and rodents. Effects of morphine on B-cell activity have mainly been tested in rodents using assays of antibody formation, which also require macrophages and T cells, preventing a conclusion as to the cell type being affected. Consistent effects on phagocytic cell function have been reported in rodents given morphine. In contrast, studies on immunomodulatory effects of morphine added to cells of the immune system in vitro have shown robust effects on some of these cell types, but not others. There is a rich literature demonstrating downregulation of phagocytic cell function by morphine, particularly for human peripheral blood mononuclear cells (PBMCs) and PMNs. Phagocytosis, chemotactic responses, interleukin production, and generation of activated oxygen intermediates and arachidonic acid products have all been reported to be inhibited. On the contrary, the literature does not support direct effects of morphine on NK cell function, is inconclusive concerning effects on B cells, and provides limited evidence for effects on T cells. The divergence between the in vivo and in vitro data suggests that effects on some cells in the immune system observed after in vivo morphine are probably not direct, but mediated. In aggregate, the literature supports the existence of an in vivo neural-immune circuit through which morphine acts to depress the function of all cells of the immune system. Further, there is strong evidence that morphine can directly depress the function of macrophages and PMNs, and modulate expression of one type of T-cell surface marker. There is, however, little evidence for direct effects of morphine on NK cells and B cells. A further complication emerges from reports of immunopotentiation of immune function in in vitro assays using endogenous opioids. The possibility of different receptors for endogenous and exogenous opioids or of interactions among the activated opioid receptors may account for these opposing effects.

A comparative study of immunomodulation produced by in vitro exposure to delta opioid receptor agonist peptides

The present study assessed the direct immunomodulatory effect of a panel of synthetic peptides exhibiting delta-opioid receptor agonist activity. Murine splenic lymphocytes and peritoneal macrophages were cultured in vitro with peptides at concentrations of 0.00001-10 microM. Assessment was made of B-cell function by quantitating cellular proliferation, T-cell function by measuring cytokine production, natural immunity by quantitating basal and cytokine-augmented natural killer (NK) cell activity, and macrophage function by production of IL-6. These peptides had minimal effects on B-cell proliferation at any concentration examined. In comparison, enhancement of cytokine production by T-helper cells occurred following exposure to several of the compounds, to a significant extent with DPDPE, DPDPE-trifluoroacetate, or deltorphin-1 and most pronounced at concentrations between 0.00001 and 0.1 microM. Likewise, IL-6 production by macrophages was significantly augmented by exposure to these three peptides. NK cell function was significantly enhanced by in vitro exposure to several of the peptides, with enhancement generally noted at concentrations between 0.00001 and 0.01 microM. However, some of the peptides (most notably DADLE) greatly suppressed NK cell activity. These data suggest that delta opioid agonists are broadly immunomostimulatory.