Effect of morphine and beta-endorphin on human Fc receptor-dependent and natural killer cell functions

The Impact of General Anesthesia on Redox Stability and Epigenetic Inflammation Pathways: Crosstalk on Perioperative Antioxidant Therapy

Worldwide, the prevalence of surgery under general anesthesia has significantly increased, both because of modern anesthetic and pain-control techniques and because of better diagnosis and the increased complexity of surgical techniques. Apart from developing new concepts in the surgical field, researchers and clinicians are now working on minimizing the impact of surgical trauma and offering minimal invasive procedures due to the recent discoveries in the field of cellular and molecular mechanisms that have revealed a systemic inflammatory and pro-oxidative impact not only in the perioperative period but also in the long term, contributing to more difficult recovery, increased morbidity and mortality, and a negative financial impact. Detailed molecular and cellular analysis has shown an overproduction of inflammatory and pro-oxidative species, responsible for augmenting the systemic inflammatory status and making postoperative recovery more difficult. Moreover, there are a series of changes in certain epigenetic structures, the most important being the microRNAs. This review describes the most important molecular and cellular mechanisms that impact the surgical patient undergoing general anesthesia, and it presents a series of antioxidant therapies that can reduce systemic inflammation.

First case report of atypical disseminated cutaneous leishmaniasis in an opium abuser in Iran

Leishmaniasis is a worldwide tropical infectious disease caused by different species of intracellular protozoa parasites of the genus Leishmania . Herein, we report a 78-year-old man with unusual diffuse cutaneous leishmaniasis (DCL) who had a history of opium abuse and chronic obstructive pulmonary disease (COPD). He had multiple papular, crusted and severely ulcerated lesions extended to his arm and chest. Direct smears and skin punch biopsy of the lesions were suggestive of leishmaniasis. Parasite DNA was amplified from ulcers, and identified as Leishmania major by PCR-RFLP, confirmed by sequencing analyses. The aim of the current study was to bring to attention this atypical form of disease in CL endemic countries. Thus, this is the first case of DCL in an opium abuser with COPD due to L. major in Northeastern Iran indicating that atypical and extensive forms of CL (DCL) owing to L. major are increasing in Iran.

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.

Immunological modifications induced from products used during the perioperative period

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

Acupuncture May Stimulate Anticancer Immunity via Activation of Natural Killer Cells

This article presents the hypothesis that acupuncture enhances anticancer immune functions by stimulating natural killer (NK) cells. It provides background information on acupuncture, summarizes the current scientific understanding of the mechanisms through which NK cells act to eliminate cancer cells, and reviews evidence that acupuncture is associated with increases in NK cell quantity and function in both animals and humans. The key contribution of this article involves the use of cellular immunology and molecular biological theory to interpret and synthesize evidence from disparate animal and human studies in formulating the 'acupuncture immuno-enhancement hypothesis': clinicians may use acupuncture to promote the induction and secretion of NK-cell activating cytokines that engage specific NK cell receptors that endogenously enhance anticancer immune function.

[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.

Enhanced immune sensitivity to stress following chronic morphine exposure

Chronic administration of escalating doses ofmorphine leads to neuroadaptive changes precipitating development of tolerance to many of the acute effects of morphine, such as analgesia, activation of the hypothalamic-pituitary-adrenal (HPA) axis and suppression of immune cell activities. Interestingly, morphine tolerance has also been shown to be accompanied by heightened immunosuppressive effects of restraint stress using a rodent model. These observations have led to the hypothesis that the altered neuronal state accompanying opioid tolerance may contribute to this enhanced immune sensitivity to stress. To further test this hypothesis using different stressors, Sprague-Dawley rats were treated chronically with morphine for at least 8 days and then challenged with either psychological (water stress) or systemic stressors [morphine withdrawal, lipopolysaccharide (10 mug/kg i.p. challenge)]. It was found that, independent of the type of stress employed, morphine-tolerant animals displayed significantly lower mitogen-stimulated blood lymphocyte responses when compared to the responses of similarly treated saline controls. To determine whether direct activation of central stress pathways may also lead to enhanced immune sensitivity, morphine-tolerant animals were centrally injected with IL-1beta (1 ng/mul i.c.v.), a cytokine that activates the HPA axis by central mechanisms. Similar to the other types of stress, this direct central challenge was also found to be more immunosuppressive in morphine-tolerant animals compared to controls. Collectively, these studies demonstrate that morphine-tolerant animals have an enhanced susceptibility to the debilitating effects of a variety of stressors on immune cell function, an effect that is likely due to the neuroadaptive changes that develop during chronic morphine exposure.

Is immunomodulation by opioid drugs of clinical relevance?

PURPOSE OF REVIEW

There has been a growing interest in elucidating the immune consequences of opioid administration for the management of pain. Several studies in vitro and in vivo have demonstrated an immunomodulating effect of opioids. The neuro-endocrine interactions observed after opioid application contribute to this effect as well as direct alterations of immune effector cells. Opioid-induced immunomodulation is mediated by opioid receptors found on immunocytes and in the central nervous system. This review will elucidate the molecular mechanisms of central and peripheral immunomodulation by opioids with special emphasis on the clinical significance of these findings.

RECENT FINDINGS

Recent research has focused on the cellular signaling cascades associated with opioid receptor activation. The crosstalk between chemokine and opioid receptors on leukocytes has opened new insights into the molecular mechanisms involved in opioid-induced immunomodulation. Heterologous desensitization and phosphorylation of chemokine receptors by opioids may not only mediate the immunosuppressive effects of opioids but may also modulate the perception of pain.

SUMMARY

Although immunomodulating effects of opioids are well established, a final statement regarding the clinical relevance cannot be made, since the existing clinical and experimental data are preliminary and inconclusive. Therefore, further clinical studies are mandatory to elucidate the influence of opioid treatment on immune regulation in different clinical settings. Further investigations may help to provide sufficient analgesia by application of opioids, as well as assessing the advantages and disadvantages on immune function.

Neuroimmunomodulatory effects of morphine in Leishmania donovani-infected hamsters

OBJECTIVE

The effect of morphine on host defense during Leishmania donovani infection in golden hamsters was studied.

METHODS

Hamsters were intracardially infected with L. donovani amastigotes and then monitored by spleen touch print microscopic examination. Morphine and naloxone were administered subcutaneously and intraperitoneally, respectively. Leukocytes were counted by a hemocytometer, and ex vivo phagocytosis was determined by the examination of stained adherent macrophages.

RESULTS

Low doses of morphine, 1.75 and 2.5 mg/kg x 2, administered subcutaneously on day 0 and day 15 significantly (p < 0.05) suppressed the infection, whereas high doses (20.0 and 50.0 mg/kg x 2) exacerbated the infection. On day 30, hamsters treated with low doses of morphine showed a significant (p < 0.05) increase in the number of circulating leukocytes and the pool size and phagocytic activity of peritoneal macrophages ex vivo; in hamsters treated with high doses, all these parameters appeared to be diminished. The bone marrow of morphine-treated hamsters showed a fall in total cellularity and no change in the number of monocytes; however, in those treated with low doses, the infection was completely eliminated by day 30, and paradoxically, a significant (p < 0.05) potentiation of infection was observed in hamsters treated with high doses. The spleens of hamsters treated with both low and high doses of morphine showed a significant (p < 0.05) decrease and increase in weight, respectively; treatment with low doses also caused an almost 2-fold increase in the percentage of monocytes. Morphine apparently exerted its protective effects via naloxone-sensitive opioid receptors; naloxone pretreatment did not affect the potentiation of infection.

CONCLUSION

Conditional doses of morphine apparently biphasically modulated the course of L. donovani infection in hamsters, at least in part through macrophage-mediated mechanisms.

Immunologic effects of opioids in the presence or absence of pain

Opioids are acknowledged to suppress immune functions following both acute and chronic administration; however, there appear to be differences according to the schedule of administration as well as the state of the organism. For example, whereas a single dose of morphine in the absence of pain is well known to be immune suppressive, the biologic consequences of this suppression are largely unknown. Repeated and chronic opioid ingestion in the absence of pain appears to result in significant consequences including high infectious disease prevalence. On the other hand, in the presence of acute pain, there is evidence that opioid administration in analgesic doses is protective. Much less is known regarding the immune and disease implications related to chronic opioid treatment for chronic pain states.

Effects of general anaesthesia on inflammation

General anaesthesia accompanied by surgical stress may influence the inflammatory responses that are essential for maintaining the homeostatic state during the postoperative course. Severe dysregulation of the inflammatory process may provoke or aggravate postoperative complications, e.g. increased susceptibility to infections, inadequate stress reactions and hypercatabolism. Anaesthetics have been suspected of impairing various functions of the immune system either directly, by disturbing the functions of immune-competent cells, or indirectly by modulating the stress response. In the past, conflicting data on the possible immunological side effects of anaesthetics have been published. Potential reasons for these controversial findings include heterogeneous patient study groups with diverse pre-existing diseases, lack of standardisation of surgical procedures, major differences in the length and severity of surgical tissue injury and a small number of randomised studies. Although the immunological effects are of minor consequence in subjects with normal immune functions, the suppression of cellular and humoral immunity following surgery and general anaesthesia may be relevant in patients with pre-existing immune disorders.

Effects of post-operative pain treatment using non-steroidal anti-inflammatory analgesics, opioids or epidural blockade on systemic and local immune responses in children

BACKGROUND

Many studies have been carried out on the effects of anaesthetic drugs and methods on the immune response, but pain and its relief also affect the immune response. We measured systemic immune responses in the blood circulation and local responses in the surgical wound when non-steroidal anti-inflammatory analgesics (NSAIDs), opioids or epidural blockade was used in the peri-operative treatment of pain.

METHODS

Responses were measured in 51 children, aged from 2 to 12 years and undergoing major surgery under balanced anaesthesia. Bolus doses of diclofenac intravenously (i.v.) and rectally (NSAID group), continuous i.v. infusion of oxycodone (opioid group) or continuous epidural infusion of bupivacaine + fentanyl (epidural group) were used peri-operatively for pain relief.

RESULTS

The only difference related to the analgesic method was shorter duration of post-operative leucocytosis and lower phytohaemagglutinin (PHA)-induced lymphocyte proliferative responses in peripheral blood in the opioid group than in the NSAID or epidural groups. By contrast, time-related alterations were seen overall in leucocyte and differential counts, lymphocyte and their subset counts, lymphocyte proliferative responses, and in serum cortisol, C-reactive protein, plasma interleukin-6 and group II phospholipase A2 concentrations and in the appearance of different cell types in the wound.

CONCLUSIONS

Post-operative pain treatments using diclofenac (NSAID), oxycodone (opioid) and epidural blockade have basically similar effects on systemic and local immune responses with only slight, probably clinically unimportant differences in children undergoing surgery under general anaesthesia.

Morphine-induced enhancement in the granulocyte response to thioglycollate administration in the rat

The present study determined the pharmacological effects of acute morphine treatment on the granulocyte phase of the peritoneal inflammatory response to thioglycollate (TG) in rats. Dual-color flow cytometry using anti-CD11b/c-PE mAb in combination with HIS48-FITC mAb allowed for the determination of morphine's effects on 4 inflammatory cell subsets: CD11b/c(+)HIS48med granulocytes; CD11b/c(hi)HIS48neg/lo activated macrophages; CD11b/c(-)HIS48(-) lymphocytes; and CD11b/c(+)HIS48hi cells (a monocyte/macrophage and granulocyte subset). Morphine produced a dose-dependent increase in a select subset of inflammatory peritoneal cells, the CD11b/c(+)HIS48med granulocytes. The effect of morphine was time-dependent, with significant effects first apparent at 4 hr after TG, but the administration of morphine 1 hr before or simultaneously with TG produced a similar increase in CD11b/c(+)HIS48med granulocytes. Naltrexone completely antagonized the morphine-induced increase in CD11b/c(+)HIS48med granulocytes. Collectively, these studies show that a single administration of morphine produces a time-dependent, dose-dependent, opioid receptor-mediated enhancement in the peritoneal granulocyte response to TG.

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.

Intravenous fentanyl increases natural killer cell cytotoxicity and circulating CD16(+) lymphocytes in humans

Opioids, including fentanyl, are often administered to patients who may be at risk for the consequences of impaired immune function. We performed a clinical study to test the effects of the synthetic opioid fentanyl on human immune function. Participants received an IV fentanyl initial dose of 3 microg/kg followed by a 2-h IV infusion of 1.2 microg x kg(-1) x h(-1). Peripheral blood was drawn before and after fentanyl administration to test for neutrophil phagocytic function, neutrophil antibody-dependent cell cytotoxicity, natural killer cell cytotoxicity, percentage of lymphocyte populations, T-lymphocyte proliferative response, and in vivo antibody response to a pneumococcal vaccine inoculation given at the end of the fentanyl infusion. Fentanyl exposure under the conditions of this study caused a rapid and significant increase in natural killer cell cytotoxicity, which was coincident with an increase in the percentage of CD16(+) and CD8(+) cells in peripheral blood. Fentanyl did not significantly affect any of the other immune measurements.

IMPLICATIONS

Many previous studies have suggested that opioid drugs can impair immune resistance in patients who may be at risk for infection. This study suggests that the opioid fentanyl, when given to healthy humans without coexisting diseases, does not suppress immune resistance. On the basis of these results, the use of fentanyl should not be restricted because of concerns that it may suppress immune function.

The in vivo effects of general and epidural anesthesia on human immune function

Impaired in vivo immunity is often observed after major surgery and is multifactorial. We conducted a randomized clinical study to determine the independent effects of general anesthesia (GA) and of lumbar epidural anesthesia (LEA) on human immune function in the absence of surgical trauma. Nineteen healthy volunteers were randomized to receive GA with thiopental and isoflurane, LEA with lidocaine, or no anesthesia (Control). Serial blood samples were tested for antibody responses to antigen inoculation, neutrophil and mononuclear cell antibody-dependent cell cytotoxicity (ADCC), natural killer cell cytotoxicity, and neutrophil phagocytic activity. Antibody responses were similar in the three groups. Mononuclear cell ADCC increased in the LEA group at the end of the anesthetic (P < 0.05 at effector/target [E/T] ratios of 10:1, 25:1, and 50:1). Natural killer cell cytotoxicity increased at the end of the anesthetic in both the LEA group (P < 0.05 at all E/T ratios) and the GA group (P < 0.05 at an E/T ratio of 5:1 and 10:1). No significant changes were observed for neutrophil ADCC or phagocytosis. General or epidural anesthesia alone, in the absence of surgery, seems to have only transient and minor effects on human immune function.

IMPLICATIONS

General or epidural anesthesia alone, in the absence of surgery, seems to have only transient and minor effects on human immune function.

Special feature for the Olympics: effects of exercise on the immune system: neuropeptides and their interaction with exercise and immune function

It is known today that the immune system is influenced by various types of psychological and physiological stressors, including physical activity. It is well known that physical activity can influence neuropeptide levels both in the central nervous system as well as in peripheral blood. The reported changes of immune function in response to exercise have been suggested to be partly regulated by the activation of different neuropeptides and the identification of receptors for neuropeptides and steroid hormones on cells of the immune system has created a new dimension in this endocrine-immune interaction. It has also been shown that immune cells are capable of producing neuropeptides, creating a bidirectional link between the nervous and immune systems. The most common neuropeptides mentioned in this context are the endogenous opioids. The activation of endogenous opioid peptides in response to physical exercise is well known in the literature, as well as the immunomodulation mediated by opioid peptides. The role of endogenous opioids in the exercise-induced modulation of immune function is less clear. The present paper will also discuss the role of other neuroendocrine factors, such as substance P, neuropeptide Y and vasoactive intestinal peptide, and pituitary hormones, including growth hormone, prolactin and adrenocorticotrophin, in exercise and their possible effects on immune function.

Endogenous morphine is produced in response to cardiopulmonary bypass in neonatal pigs

BACKGROUND

Cardiopulmonary bypass (CPB) is associated with a systemic inflammatory response. Endogenous morphine production has previously been demonstrated in humans after cardiac surgery with CPB. It has been hypothesized that morphine plays a role as an anti-inflammatory mediator in the systemic inflammatory response. The aim of this study was to investigate if the CPB procedure in itself elicits an endogenous morphine production in neonatal pigs.

METHODS

Endogenous morphine production was measured in arterial blood in piglets exposed to sternotomy alone (sham group, n=10) or sternotomy and CPB (n=10). Blood samples were obtained immediately after the induction of anaesthesia, at the end of CPB and 4 h later. Morphine in arterial blood was detected by radioimmunoassay and confirmed by gas chromatography mass spectrometry.

RESULTS

Animals undergoing CPB showed detectable endogenous morphine concentrations immediately after CPB, with increased concentrations postoperatively. There was no measurable morphine production in the sham operated pigs.

CONCLUSION

The CPB procedures elicits an endogenous morphine production in neonatal pigs. This morphine response is analogous to the previously demonstrated response in patients subjected to cardiac surgery and CPB.

Special feature for the Olympics: effects of exercise on the immune system: neuropeptides and their interaction with exercise and immune function

It is known today that the immune system is influenced by various types of psychological and physiological stressors, including physical activity. It is well known that physical activity can influence neuropeptide levels both in the central nervous system as well as in peripheral blood. The reported changes of immune function in response to exercise have been suggested to be partly regulated by the activation of different neuropeptides and the identification of receptors for neuropeptides and steroid hormones on cells of the immune system has created a new dimension in this endocrine-immune interaction. It has also been shown that immune cells are capable of producing neuropeptides, creating a bidirectional link between the nervous and immune systems. The most common neuropeptides mentioned in this context are the endogenous opioids. The activation of endogenous opioid peptides in response to physical exercise is well known in the literature, as well as the immunomodulation mediated by opioid peptides. The role of endogenous opioids in the exercise-induced modulation of immune function is less clear. The present paper will also discuss the role of other neuroendocrine factors, such as substance P, neuropeptide Y and vasoactive intestinal peptide, and pituitary hormones, including growth hormone, prolactin and adrenocorticotrophin, in exercise and their possible effects on immune function.

Phenotypic analysis of splenocyte subsets following acute morphine treatment in the rat

Prior studies by our laboratory demonstrated that a single injection of morphine produces dose-dependent, naltrexone-reversible, suppressive effects in assays of mitogen-stimulated lymphocyte proliferation and natural killer (NK) cell cytotoxicity in the spleen. The present study used flow cytometry to assess directly whether acute morphine treatment produces these immune alterations by altering the leukocyte composition of the spleen. In agreement with our previous findings, morphine suppressed the concanavalin A-stimulated proliferation of T cells, lipopolysaccharide-stimulated proliferation of B cells, and NK cell cytotoxicity in the spleen. However, the same morphine treatment protocol did not alter the total number of splenic leukocytes, the percentage of live splenic leukocytes (as assessed by forward-scatter versus side-scatter histograms), or the relative number of CD4(+)CD3(+) T cells, CD8(+)CD3(+) T cells, CD45RA/B(+) B cells, NKR-P1A(hi)CD3(-) NK cells, NKR-P1A(lo)CD3(+) T cells, CD11b/c(+)HIS48(-) monocytes/macrophages, or CD11b/c(+)HIS48(+) granulocytes in the spleen. These findings indicate that the effects of a single sc dose of morphine on functional measures of immune status in the spleen do not result from a redistribution of splenic leukocytes; instead, morphine's effects likely result from direct alterations in leukocyte activities.

Opioid use in the management of chronic pain

Opioids are a necessary and effective component of the management of chronic non-cancer-related pain in some patients. Careful structuring, monitoring, and documentation of care are important, but the therapeutic use of opioids is uncomplicated in the majority of patients using opioids and is gratifying for both the patient and the treating physician when it results in significant reduction in pain, improvement in level of function, and a higher quality of life. Opioid therapy is most often successful when combined with other pharmacologic and nonpharmacologic interventions as indicated by the type of pain and the context in which it occurs.

A role for NK cells in greater susceptibility of young rats to metastatic formation

Cancer is the second leading cause of death in children (after accidents) and is more prevalent in the first 5 years of life than in the subsequent 10 years. Very young animals have been shown to be more susceptible to malignant growth and whether such increased susceptibility is attributable to reduced resistance of the host to tumor development or to increased incidence of cancerous cells is, as yet, unclear. In the current study, we used 36 day old male and female rats and adult rats to specifically study the role of natural killer (NK) cell activity, as well as hormones known to regulate their activity, in mediating reduced resistance to tumor metastasis at prepubescence. A mammary adenocarcinoma cell line (MADB106) syngeneic to the Fischer 344 rat was used. Following i.v. injection, MADB106 tumor cells seed and colonize only in the lungs, a process shown in adult rats to be controlled by NK cells during the first 24 hours after tumor inoculation. As was found in our previous studies, young rats demonstrated a 10-fold higher percentage of lung tumor cell retention compared to adult rats. Importantly, this higher percentage of tumor cell retention was evident using the same number of tumor cells per kg of body weight in young and adult rats, and maintained even when young rats were challenged with 10- and 100-fold fewer MADB106 cells per kg than adults. Selective depletion of NK cells markedly increased tumor cell retention in all rats, indicating that NK cells play a crucial role in resistance against MADB106 retention in both young and adult rats. Employing in vitro assessment of whole blood NK cytotoxicity. young animals exhibited markedly less specific killing compared to the mature animals. Taken together, these findings indicate a reduced resistance of the young rats against MADB106 retention that is mediated by diminished NK activity in these rats. Factors other than NK cells appear to play a minor role determining age differences in this model. Age- and sex-related differences in plasma beta-endorphin and corticosterone levels were also found, suggesting different activation levels of the HPA axis. These differences, however, seen unlikely to underlie the reduced NK activity in young rats.

Laparoscopic-assisted vs. open surgery for colorectal cancer: comparative study of immune effects

PURPOSE

Our aim was to test the hypothesis that laparoscopic-assisted resection for colorectal cancer has an immunologic advantage over traditional open surgery.

METHODS

Sixteen patients with colorectal cancer were randomized to undergo laparoscopic-assisted resection or open surgery. Basic patient data were recorded, and serum interleukin-6 levels, relative proportions of lymphocytes, and human leukocyte antigen-DR expression on monocytes were determined at specific time intervals.

RESULTS

Operating time was longer for laparoscopic-assisted resection (P=0.02), but analgesic requirements were less (P=0.04). All patients exhibited the following: interleukin-6 levels increased to a maximum at 4 hours and returned to preoperative levels within 48 hours. This response appeared greater for open resection (mean peak level, 313 vs. 173 pg/ml; P=0.25). Relative granulocytosis (P < 0.001) was seen within 48 hours, which was offset by a decrease in percentage of lymphocytes (P < 0.001). Changes in lymphocyte subfractions were most significant seven days postsurgery: natural killer cells decreased (P=0.003); T cells increased (P=0.008), with elevation in the CD4/CD8 ratio (P=0.003). B cells were largely unchanged at all time periods. Human leukocyte antigen-DR expression on monocytes was significantly less at 48 hours postsurgery (P < 0.001). All changes were reversed within three weeks of surgery. There were no differences when comparing laparoscopic-assisted resection with open surgery.

CONCLUSIONS

Both laparoscopic-assisted resection and open surgery affect the immune response. It would appear that laparoscopic-assisted resection does not have an immunologic advantage over open surgery in patients with colorectal cancer.

Opiates and infection

This review on the effects of opiate use on infectious diseases discusses the complete spectrum of infections in the opiate user, including those of the lung, the GI tract, the skin, the skeletal system, and the CNS. There is both increased prevalence and increased severity of bacterial and viral infections in injection drug users with the outcome of increased morbidity and mortality. The experimental administration of opiates has lead to a greater understanding of the effects on susceptibility to and progression of infectious diseases. Animal models of opiate dependence and infection are reviewed with specific attention to cases in which the opiate-mediated effects are harmful and in which cases they are beneficial.

Evidence for central opioid receptors in the immunomodulatory effects of morphine: review of potential mechanism(s) of action

This review will discuss studies demonstrating that activation of opioid receptors within the central nervous system alters various immune system parameters. Specifically, natural killer cell cytolytic activity and lymphocyte proliferative responses to mitogen appear to be modulated predominantly, if not exclusively, through central opioid receptors. The potential mechanisms by which central opioid receptors appear to modulate these peripheral immune functions will be examined by evaluating the role of both the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system. The studies discussed below indicate that acute administration of morphine or related compounds appears to primarily alter peripheral immune function through the sympathetic nervous system, while more prolonged exposure to opioids alter the immune system predominantly by activation of the HPA axis. Finally, the potential clinical relevance of these observations are discussed in relationship to both the therapeutic use, as well as the abuse of opioid compounds.

Comparison of the in vivo effects of morphine and methadone on natural killer cell activity in spleen, peritoneal cavity, and lungs in rats

Opiates and opioid agents are known to affect the immune system. In humans this includes alterations in natural killer (NK) cell activity. Morphine is reported to reduce in vivo spleen NK activity in rats, whereas for methadone only in vitro data have been described. In the present paper we describe a systematic study on the chronic effects of well-known opiates, comparing for the first time the effects of morphine and methadone on NK cell activity in various organs: in addition to spleen, also in the peritoneal cavity, and lungs. In all organs the NK activity was determined using three effector: target cell ratios. Morphine and methadone given by food during 6 weeks decreased the NK cell activity in rat spleen, supporting published data on morphine. The role of the opiate receptor is discussed. However, the overall action of morphine could not be described as suppressive because stimulation of NK cell activity in the peritoneal cavity and lungs by morphine was found. In contrast, methadone induced a decrease in the NK cell activity in these organs. Apart from these differential expressions of morphine- and methadone associated effects on NK cell activity, the findings demonstrate the potential adverse effects of these opiates on an important antiviral defence mechanism.

Effects of anesthesia based on large versus small doses of fentanyl on natural killer cell cytotoxicity in the perioperative period

Surgical stress and general anesthesia suppress immune functions, including natural killer cell cytotoxicity (NKCC). This suppression could be attributable, at least in part, to opiates. We have previously shown that large-dose fentanyl administration suppressed NKCC in rats. The present study sought to compare the effects of two anesthetic protocols, based on large- (LDFA) versus small (SDFA)-dose fentanyl anesthesia on NKCC in the perioperative period. Forty patients were included in this study; half were assigned to each protocol of anesthesia. In each anesthetic group, half the patients were undergoing surgery for malignant diseases, and half for benign conditions. Blood samples were collected during the perioperative period. NKCC was assessed using the chromium release assay. Initially, both types of anesthesia similarly suppressed NKCC, with a peak effect 24 h after surgery. The two types of anesthesia, however, differed in the rate of recovery of NKCC suppression. By the second postoperative day, NKCC returned to control values in the SDFA patients, whereas NKCC was still significantly suppressed after LDFA. These results indicate that LDFA causes prolonged suppression of NK cell function. Whether this suppression might have a long-term impact on the overall outcome, especially in cancer patients, remains to be determined.

Awake epidural anesthesia is associated with improved natural killer cell cytotoxicity and a reduced stress response

BACKGROUND

Laparotomy under general anesthesia is associated with depressed natural killer cell cytotoxicity (NKCC) and compromised clearance of tumor cells. We tested the hypothesis that awake epidural anesthesia (AEA) improves NKCC compared to conventional general endotracheal anesthesia (GEA).

PATIENTS AND METHODS

Preoperative, perioperative, and postoperative (day 3) NKCC, plasma epinephrine, norepinephrine, cortisol levels, and 24-hour urinary cortisol levels were measured in 20 patients undergoing open colectomy under either AEA or GEA.

RESULTS

Preoperative and postoperative measurements were not significantly different in the two groups. Patients receiving GEA had a significant reduction in NKCC from 36% +/- 4% preoperatively to 22% +/- 4% perioperatively (P = 0.02). Patients receiving AEA had no significant change in NKCC. Perioperative plasma epinephrine and cortisol levels were higher with GEA than AEA. The perioperative 24-hour urinary cortisol excretion values were significantly higher in the group receiving GEA, suggesting a greater stress hormone response in this group compared to AEA patients.

CONCLUSIONS

Compared to GEA, AEA appears to preserve perioperative NKCC. This effect may be related to an attenuated stress hormone response associated with AEA. Cancer patients may have improved killing of embolized tumor cells during surgery performed under AEA.

The effects of the opiate antagonist naloxone on measures of cellular immunity during rest and brief psychological stress

This study investigated subjective, cardiovascular, and cellular immune system responses in 20 healthy young men during brief mental arithmetic stress compared with a video-watching control task. The role of endogenous opioids in mediating the immunological change to stress was examined by pre-task administration of the opiate antagonist naloxone. Immune changes were followed over a 1 hr post-task period. The results indicate significant physiological arousal and subjective distress as well as increases in NK cell cytotoxicity, numbers of circulating CD8 suppressor/cytotoxic T cells and NK lymphocytes following mental arithmetic but not the control task. Immune measures generally returned to baseline by 1 hr after the stress. Naloxone did not block the increase in NK cell activity or cell numbers following the stressor and had no effect on the other physiological or subjective measures. Thus, the results do not support endogenous opioids as a primary mechanism for immune changes to this type of acute stress. Naloxone did, however, increase NK cell cytotoxicity during the video task without effecting NK cell numbers, suggesting naloxone itself can increase per-cell NK cytotoxicity. Affective ratings for the week preceding testing were inversely related to the increase in NK cell numbers during mental arithmetic. If the increase in NK cell numbers under brief stress is part of an adaptive response to potential injury, then our data suggest that increases in general distress may impede normal immune system adaptation. Acute stress paradigms may be used as potential probes for investigations of individual differences in immune system responsivity.

Beta-endorphin and the immune system--possible role in autoimmune diseases

The immune system and the neuroendocrine system are closely interconnected having such means of bidirectional communication and regulation. In this review, a hypothesis is put forward regarding the possible role of beta-endorphins in the pathogenesis of autoimmune diseases: It is suggested that the increased cytokine production in immunoinflammatory disorders induces production of beta-endorphins from the pituitary and the lymphocytes; the enhanced level of beta-endorphin causes inhibition of human T helper cell function, which potentially down-regulate the antibody production. Also the beta-endorphin-induced enhancement of the natural killer cell activity may suppress the B cell function. In addition, beta-endorphin also exerts a direct inhibitory effect on the antibody production. Thus, in autoimmune disorders the enhanced cytokine level may via stimulation of the production of beta-endorphins exert a negative feed back on the antibody production and potentially so on the production of autoantibodies.

Perioperative immunomodulation in cancer surgery

Despite undergoing a curative resection, many patients with colorectal cancer will develop and die of metastatic disease. It has been shown clinically and experimentally that surgery causes a transient period of immunosuppression, and it is postulated that this may encourage both the implantation of surgically disseminated tumor cells and the growth of existing micrometastases. The present study used natural killer cell cytotoxicity (NKCC) and tumor burden to evaluate perioperative modulation of immunocompetence in a murine model. We measured NKCC and tumor burden responses to a standardized surgical stress (SSS) alone, and to either morphine sulfate (MS) (15 mg/kg subcutaneously x 4 doses), ketorolac (a prostaglandin synthetase--prostaglandin E2--inhibitor) (2.5 mg/kg subcutaneously x 4 doses), or interleukin 2 (2,000 units intraperitoneally x 3 doses) administration with the SSS. In this model, we found that both low-dose interleukin-2 (IL-2) and ketorolac reversed the NKCC suppression associated with surgery, whereas morphine resulted in further depression of NKCC. In addition, IL-2 significantly decreased tumor incidence, whereas continuous MS exposure markedly increased tumor burden after surgery. These data suggest that IL-2 and ketorolac may be effective agents for the restoration of perioperative immune competence, whereas the use of continuous morphine might have significant deleterious effects.

Effect of synthetic thymic hormones on the cocaine-induced inhibition of the primary immune response in mice

The effects of thymosin alpha 1 (T alpha 1) and thymopentin (TP5) on the cocaine-induced impairment of the primary antibody response to sheep red blood cells (SRBC) was studied. The administration of cocaine from day -4 to the day of immunization (day 0) induced a significant impairment of the response to the T-dependent antigen SRBC, as evaluated on day 5 post-immunization by the Splenocyte-Induced SRBC Hemolysis (SIH) assay. The analysis of the responses to immunogen elicited from each single mouse indicated that, under the experimental conditions used, cocaine acted by exerting more an "all or nothing" effect rather than by modulating the strength of the immune response. Both T alpha 1 and TP5, injected into mice during cocaine administration and for 4 days after, induced a significant recovery of the response to SRBC. Our experiments did not show any great differences in the overall efficacy of the two drugs, although they showed quite a different dose-response effect. The results of the present investigation demonstrated the capability of TP5 and T alpha 1 to reverse the cocaine-induced impairment of the response to SRBC and suggested that the effect of the two peptides may be related to their immunomodulating activities on T-cell functions.

Endogenous opiates: 1992

This paper is the fifteenth installment of our annual review of research concerning the opiate system. It includes papers published during 1992 involving the behavioral, non-analgesic, effects of the endogenous opiate peptides. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal and renal function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.

In vitro phencyclidine-induced inhibition of lymphocyte proliferation: prevention by cell activation

The proliferative response of phytohemagglutinin (PHA)- and interleukin 2 (IL-2)-activated murine splenocytes was studied in the presence of phencyclidine (PCP), a potent psychotomimetic drug of abuse. PCP inhibited [3H]-thymidine incorporation in lymphocytes treated with PHA or IL-2. This inhibitory action was dependent upon the drug doses and the time of incubation with the cultures. There was no significant inhibitory activity of PCP when it was added 24 hrs or 48 hrs after mitogenic stimuli. Parallel, a lower inhibitory effect was observed when IL-2 or PHA were simultaneously present in the incubation medium. Moreover, the pretreatment for 18 hrs with IL-2 completely counteracted PCP-induced depression of PHA-stimulated lymphocytes. We suggest that PCP affects some pathway that regulates the activation of resting T cells rather than affecting already cycling cells.

Rhythms in the immune system

This report reviews the evidence that cells within the immune system are subject to rhythmic influences that affect numbers of circulating cells and their function both in vitro and in vivo. It is concluded that, although periodicity has clearly been demonstrated for numbers of immunocompetent cells in the circulation, significant functional changes have not been consistently observed. A number of neuroendocrine hormones, which modulate immune responsiveness in vitro and which are released in a rhythmic manner, are considered as mediators of the observed effects on the immune system and this is related to changes in expression and activity of immune-mediated diseases such as rheumatoid arthritis.

Human immune toxicity

This review examines xenobiotic toxicity to the immune system, stressing in particular those aspects of most relevance to humans. Immunotoxicity is examined especially from three points of view: by what immunological component is affected, by classes of foreign agents that adversely affect the human immune system and by critical evaluation of human case reports and epidemics. Mechanisms by which xenobiotics interrupt cytokine networks are emphasized. The concept that microbial agents, both environmental as well as infectious, may act as immunotoxicants, either alone or in synergism with conventional agents is introduced. Instances of human immunotoxicology are critically evaluated in terms of clinical relevance, i.e. whether increased susceptibility to opportunistic infections or tumor emergence takes place in the affected individuals.