Immunomodulation by cocaine--a neuroendocrine mediated response

Cocaine modulation in vitro of tumor necrosis factor production by macrophages from retrovirally infected mice

The effect of cocaine and LP-BM5 murine leukemia retrovirus infection on tumor necrosis factor (TNF) production were investigated. Three types of macrophages were used 1) peritoneal macrophage (PM), 2) thioglycollate induced peritoneal macrophage (TPM), and 3) alveolar macrophage (AM). Cells were cultured with and without cocaine during in vitro stimulation by lipopolysaccharide (LPS) and gamma-interferon (IFN). Retroviral infection enhanced the TNF production by PM and AM, but not by TPM. Intraperitoneal cocaine injection reduced TNF production by PM, but increased TNF production by AM and TPM. TNF production by AM from cocaine injected mice was stimulated by cocaine applied in vitro. In contrast, 100 micrograms/ml of cocaine in vitro significantly inhibited the TNF production by TPM from uninfected and retrovirally infected mice. Thus, TNF production by macrophages is modulated by murine retroviral infection and cocaine treatment. This could play an important role in host defense.

In vitro effects of 'designer' amphetamines on human peripheral blood mononuclear leukocytes proliferation and on natural killer cell activity

Human peripheral blood mononuclear leukocytes (PBML) proliferation was measured in the presence or absence of amphetamines. Proliferation in response to T-cell mitogen PHA was suppressed from 22 to 34% by d- and dl-amphetamine, respectively, contrarily to 1-form which did not affect proliferation of PHA-stimulated PBML. The 'designer' amphetamines appeared to be more potent inhibitors of PBML proliferation induced by both PHA and PWM stimulation than those of the racemic and isomeric forms of amphetamine. A wide variation was seen in the suppressive actions of the 'designer' amphetamines, and the mean percentages of suppression varied from 12 to 45% compared with the control values. 4-Propoxy-amphetamine (4-PA) was found to be the most active among the 'designer' drugs. In vitro effects of d-, 1- and dl-amphetamine were also studied on natural killer (NK) cell activity. A marked increase in the NK cell activity was observed only in the presence of very low concentrations (10(-12) to 10(-10) M) of dl-amphetamine, however, the activity of the NK cell remained within the control limits in the presence of d- or 1-forms. The findings suggest that the abuse of amphetamines, especially the 'designer' drugs, may adversely affect the activity of immunoregulatory cells and might lead to a compromised immune system in amphetamine abusers.

Ethanol enhances immunosuppression induced by cocaine

Use of cocaine concurrently with alcohol is prevalent among cocaine addicts. Cocaine has been shown to inhibit phytohemagglutinin- and ConA-induced proliferation of T-lymphocytes, NK cell cytotoxicity, and phagocytic activity of peritoneal macrophages. In some studies no effects of cocaine on the immune response have been observed, although on the contrary, others show it increased the NK cell activity and serum antibody response to T-dependent antigen. Effects of cocaine on the immune system may be mediated by its neurostimulatory action on the hypothalamo-pituitary-adrenal axis. ACTH, beta-endorphine, and corticosterone released under the action of cocaine exert various inhibitory effects on the immune function. We studied the immunotoxic effect of cocaine, combination of cocaine with ethanol, and cocaethylene, a derivative formed from cocaine and ethanol in the body, on the mitogen-stimulated production of cytokines by splenocytes. C57BL mice were injected twice daily with 20 mg/kg cocaine or equivalent dose of cocaethylene and received a liquid Lieber-DeCarli diet containing ethanol (26% of total calories) or isocaloric amount of maltose-dextrin. After 3 weeks of treatment, cocaine and cocaethylene caused a significant decrease of the spleen weight and total number of splenocytes. In splenocytes isolated from the cocaine- or cocaethylene-treated mice, mitogen-stimulated production of gamma-interferon, tumor necrosis factor, and interleukin-2 was suppressed, in all cases more severely when cocaethylene was used. Thus, formation of cocaethylene during simultaneous consumption of cocaine and ethanol may enhance the immunotoxicity of cocaine.

Chronic ethanol and cocaine-induced hepatotoxicity: effects of vitamin E supplementation

The mechanisms of chronic cocaine toxicity and its potentiation by ethanol were investigated. Cocaine was administered to male C57BL/6 mice (20 mg/kg by peritoneal injection twice a day) alone or in combination with ethanol-containing diets (26% of total calories) supplied with a normal (20 IU/liter) or high content (170 IU/liter) of vitamin E. Liver levels of vitamin E, reduced glutathione, ascorbic acid, and hydroxyproline were measured. Accumulation of thiobarbituric acid-reactive substances, after in vitro stimulation of lipid peroxidation by Fe3+/ADP/ascorbate system, was measured as an index of susceptibility of hepatic membranes to oxidative stress. Plasma alanine aminotransferase, lethality, liver weight, and liver/body weight ratio were determined to assess the extent of liver toxicity. Consumption of ethanol exacerbated liver toxicity induced by cocaine treatments and reduced survival, but ethanol or cocaine treatments alone caused no or only modest mortality. Ethanol potentiated cocaine-induced accumulation of collagen in the liver and depletion of ascorbic acid. Hepatotoxicity induced by the combined ethanol plus cocaine treatment was not accompanied by a decrease in intracellular vitamin E or glutathione content. There were no changes in the basic levels and in the rate of accumulation of thiobarbituric acid-reactive substances in liver homogenates under the lipid peroxidation-stimulating system in vitro. The toxic effects of ethanol and cocaine were not reduced by the ingestion of vitamin E during short-term exposure of 21 days of treatment.

Modification of thymic cell subsets induced by long-term cocaine administration during a murine retroviral infection producing AIDS

LP-BM5 murine leukemia virus (MuLV) infection and cocaine administration are known to impair the murine immune system. We have developed a murine model to study the effect of daily cocaine administration and retrovirus infection on the lymphoid cell populations of the thymus. C57BL/6 female mice were studied following chronic cocaine administration for 11 weeks with simultaneous LP-BM5 MuLV infection. Cocaine administration reduced body and thymus weight, significantly reduced the number of CD8+ cells in the thymus, and partially prevented thymus enlargement due to lymphoid cell proliferation induced by LP-BM5 MuLV infection. Retrovirus infection was associated with a decrease in the percentage and absolute number of Thy 1.2+, CD4+, and CD8+ cells in the thymus, an effect potentiated by cocaine administration. Therefore cocaine impairs thymic function by altering the number of cells expressing T cell differentiation markers in MAIDS.

Modification of spleen cell subsets by chronic cocaine administration and murine retrovirus infection in normal and protein-malnourished mice

We have developed an experimental mouse model to study the effect of daily cocaine administration on the immune system during an acquired immune deficiency syndrome (AIDS). Mice were infected with LP-BM5 murine leukemia virus, a retrovirus which causes immunosuppression with the development of functional murine AIDS. Increasing doses of cocaine given by daily intraperitoneal injection for 11 weeks reduced body weight. A daily cocaine injection in some mice as well as a saline injection in others showed a decrease in the percentage of Thy 1.2+, CD4+ and CD8+ cells, while both treatments increased the percentage and absolute numbers of B-cells per spleen. Saline and cocaine treatment induced an increase in gamma-IFN and TNF-alpha production by splenocytes. Cocaine treatment favored a decrease in sIL-2R secretion. Saline and cocaine treatment had slightly different effects on the splenocytes of protein-malnourished mice. Cocaine treatment induced an increase in the percentage of CD8+ cells. Saline and cocaine treatments decreased the number of Mac 1+ cells in the spleen. Moreover, saline- and cocaine-treated protein-malnourished mice splenocytes did not present the increase in gamma-IFN production as well-nourished mice splenocytes showed. Retrovirus-infected mice showed a decrease in the percentage of Thy 1.2+ and CD8+ cells and an increase in the percentage and absolute numbers of CD4+, IL-2R+, Mac 1+ and B-cells. Cocaine partially prevented the enlargement of lymphoid organs due to lymphoid cell proliferation induced by murine retrovirus infection, but had little effect on the elevated percentage of CD4+ cells or B-cells or the depressed numbers of CD8+ cells associated with virus infection. However, cocaine did reduce the number of activated IL-2R+ cells and macrophages (Mac 1+) in addition to reducing the total number of cells per spleen in all subsets in retrovirus-infected mice, but not in uninfected controls. Cocaine treatment and retrovirus infection alone or in combination suppressed the release of sIL-2R into supernatant fluid during in vitro culture of splenocytes. These data illustrate that cocaine treatment modulates cell proliferation in retrovirus-infected mice and thus modifies the absolute number of cells in those subsets already altered by retrovirus infection. Retrovirus-infected and retrovirus-infected cocaine-treated protein-malnourished mice showed similar results.

Cocaine-induced suppression of interferon-gamma secretion in leukocytes from young and old C57BL/6 mice

The effects of cocaine (0.1-100 micrograms/ml) were studied on interferon-gamma (IFN) secretion in Con A-stimulated splenocytes from young (4 months) and old (18 months) C57BL/6 mice. IFN secretion was significantly suppressed by cocaine in a concentration-dependent manner. Suppression was observed in splenocytes from both young and old mice. Splenocytes from young mice released higher amounts of IFN (23.40 +/- 1.47 ng/ml) than those from old mice (6.10 +/- 0.35 ng/ml) after 24 h in culture. The concentration of Con A used to stimulate IFN secretion significantly affected the suppressive effect of cocaine. Pretreatment of splenocytes with cocaine followed by culture in the absence of cocaine did not affect IFN secretion in old mice, while splenocytes from young mice showed a sustained depression in IFN release. This suggests that cocaine suppresses IFN release in vitro and the susceptibility to this inhibitory effect may be age related.

Effect of murine retroviral infection on hair and serum levels of cocaine and morphine

LP-BM5 retrovirally infected female C57BL/6J mice were administered cocaine, morphine or both by daily intraperitoneal injection for 9 weeks. Drug concentrations were measured by radioimmunoassay in serum and in hair extracts. Hair samples obtained from all drug-treated mice were positive for the drug injected, while none of the saline-treated mice had detectable drug levels in hair or serum. The average morphine concentration obtained from non-infected mice was 11 ng/mg hair whereas the amount found in the LP-BM5-infected mice was significantly higher (20 ng/mg hair). Mice injected with both morphine and cocaine were given 50% of the regular dose of each drug and drug levels in the hair of these animals were approximately half that of mice injected with the full dose of the single drug. Non-infected mice treated with both drugs had a mean value of 7 ng morphine/mg hair and 374 ng cocaine/mg hair while retrovirus-infected mice had significantly higher concentrations, 10 ng morphine/mg hair and 1160 ng cocaine/mg hair (P less than 0.001). Serum concentrations of cocaine and morphine were significantly higher (P less than 0.01) in the retrovirus-infected animals from 40 min to 1.5 h. The increased concentrations of cocaine and morphine in serum during retrovirus infection are accompanied by a significant increase in the amount of drug incorporated into the hair matrix. This change indicates that retroviral infection may influence the disposition of these drugs in the systemic circulation.

Oral effects of drug abuse

Drug abuse is a major problem in the U.S. and most other countries of the world today. Many studies, surveys, and case reports have described the adverse social and medical effects of drug abuse; yet surprisingly little is known about the specific effects of many of these drugs in the oral cavity. This article reviews the current state of knowledge concerning the systemic and oral effects of drugs of abuse and the dental management of addicted patients.

Critical role of endogenous corticotropin-releasing factor (CRF) in the mediation of the behavioral action of cocaine in rats

The role of endogenous CRF in the locomotor hyperactivity induced by cocaine was investigated by using the immunoneutralization of endogenous CRF and an antagonist of CRF-receptors (alpha-helical CRF9-41: alpha h-CRF) in rats. Different dilutions of anti-CRF antibody (1:5, 1:20, but not 1:100) injected intracerebroventricularly (i.c.v.) 24 hours before the cocaine treatment blocked the expression of locomotor hyperactivity. Pretreatment with different doses (0.001, 0.01, 0.1, 1.0 micrograms i.c.v.) of alpha h-CRF inhibited the locomotor hyperactivity induced by cocaine dose-dependently. Neither the immunoneutralization nor the receptor blockade for CRF changed the hyperactivity induced by another locomotor stimulant caffeine. These results serve as indirect in vivo evidence of the selective role of endogenous CRF in the cocaine-induced behavioral alterations. The findings have implications as concerns the possible role of CRF in human psychopathological changes induced by cocaine.

Cocaine immunotoxicity: abnormal cytokine production in Hispanic drug users

Peripheral blood lymphocytes from 47 Hispanic poly-drug users with a history of cocaine abuse were analyzed for in vitro production of interleukin-1 (IL-1), interleukin-2 (IL-2), gamma-interferon (IFN) and plasma levels of soluble IL-2 receptor (SIL-2R). Cocaine use was confirmed and quantified by analysis of hair and urine samples, and subjects were grouped into 3 based on the extent of cocaine metabolites detected. No significant differences in IL-1 and IFN production were seen between the 3 groups. However, subjects with higher levels of cocaine in hair also showed higher levels of IL-2. In addition, a positive correlation was seen between cocaine concentrations and IL-2 levels. A corresponding negative correlation was seen between cocaine levels and levels of plasma SIL-2R. These findings suggest modulation of the IL-2 network by cocaine in poly-drug users.

Stimulation of natural killer cell activity by murine retroviral infection and cocaine

The effects of cocaine and murine AIDS on natural killer (NK) cell activity in C57BL/6 mice was studied. Cocaine may play a major role in the development and progression to AIDS in the human population. Chronic intraperitoneal injection of cocaine was shown to cause an increase in NK cell activity over those of saline-treated animals. Infection with LP-BM5 murine leukemia retrovirus was also shown to increase NK cell activity. NK cell activity was increased in retrovirally infected mice treated with cocaine beyond that of mice treated with cocaine alone. This study indicates an important immunomodulatory effect of cocaine on NK cell activity, especially when combined with the effects caused by retroviral infection.

AIDS, drugs of abuse and the immune system: a complex immunotoxicological network

Two of the most interesting questions often asked about AIDS is why many people do not become immunodeficient or get complicating disease when first infected with Human Immunodeficiency Virus (HIV) and what are the "risk factors" making some individuals more susceptible to the disease. A large majority of people with AIDS have a well established history of drug and alcohol abuse. Both drugs of abuse and alcohol have immunotoxic properties as evidenced by a number of studies. These include marked changes in the cellular, humoral and other components of the immune defense mechanism. Such a compromise of the immune system can render it susceptible to the development of AIDS after HIV infection. This paper reviews the evidence suggesting possible links between substance abuse and its immunotoxicology, and their possible roles in the pathogenesis of AIDS.

Splenocyte subsets in normal and protein malnourished mice after long-term exposure to cocaine or morphine

An experimental model which resembles human drug addiction was developed to study the effect of chronic drug (cocaine or morphine) administration on the immune system. As malnutrition has been associated with drug use, a low protein diet has been evaluated for its contribution to the impairment of the immune system during cocaine/morphine addiction. Female C57BL/6 mice that received a 20% or 4% casein diet were studied. Both drugs were administered intraperitoneally daily for 11 weeks and drugs were administered in increasing daily doses, beginning after 3 weeks of diet consumption. Doses of cocaine began with 5 mg/kg body weight and reached the maximum dose of 40 mg/kg/day at the fourth week. Doses of morphine gradually increased from 10 mg/kg to 75 mg/kg body weight with the maximum dose reached after 5 weeks of treatment. Cocaine administration reduced body weight, particularly in the low protein diet group, and spleen weight in protein malnourished mice. Cocaine as well as saline injected mice showed a decrease in the percentage of CD4+ CD8+ and Mac-1+ cells and an increase in B cells in the spleens of well nourished mice. Morphine-treated mice showed similar results to those observed in cocaine or saline treated mice. These results suggest that cocaine, morphine or saline injection can alter the percentage of cells that express a defined phenotype independently of the nutritional status of the subject. Moreover, the effect appears dependent on a stress mediated process.

Effects of cocaine and morphine on IgG production by human peripheral blood lymphocytes in vitro

Elevated serum levels of IgG are amongst the immunological abnormalities exhibited by intravenous drug addicts. We therefore addressed the hypothesis that cocaine and morphine (the major metabolite of heroin) exert a direct effect on human B cell function in vitro. Human peripheral blood mononuclear cells from normal individuals were incubated for 7 days with the T cell-dependent B cell activator pokeweed mitogen (PWM) and serial dilutions of either cocaine or morphine. At the end of this time total IgG was measured by use of a sandwich ELISA incorporating a biotin-labelled affinity-purified anti-IgG and streptavidin peroxidase. At concentrations relevant to those found in plasma, morphine and cocaine did not affect PWM-stimulated IgG synthesis in vitro. We suggest that these drugs of abuse do not directly influence human B cells, but in vivo exert immune modulatory effects via indirect mechanisms.