Cocaine suppresses proliferation of phytohemagglutinin-activated human peripheral blood T-cells

HIV Tat and cocaine interactively alter genome-wide DNA methylation and gene expression and exacerbate learning and memory impairments

Cocaine use is a major comorbidity of HIV-associated neurocognitive disorder (HAND). In this study, we show that cocaine exposure worsens the learning and memory of doxycycline-inducible and brain-specific HIV Tat transgenic mice (iTat) and results in 14,838 hypermethylated CpG-related differentially methylated regions (DMRs) and 15,800 hypomethylated CpG-related DMRs, which are linked to 52 down- and 127 upregulated genes, respectively, in the hippocampus of iTat mice. These genes are mostly enriched at the neuronal function-, cell morphology-, and synapse formation-related extracellular matrix (ECM) receptor-ligand interaction pathway and mostly impacted in microglia. The accompanying neuropathological changes include swollen dendritic spines, increased synaptophysin expression, and diminished glial activation. We also find that sex (female) and age additively worsen the behavioral and pathological changes. These findings together indicate that chronic cocaine and long-term Tat expression interactively contribute to HAND, likely involving changes of DNA methylation and ECM receptor-ligand interactions.

Elevated Neutrophil to Lymphocyte Ratio in Older Adults with Cocaine Use Disorder as a Marker of Chronic Inflammation

Objective

The neutrophil to lymphocyte ratio (NLR) is a non-specific, easy-to-obtain marker of inflammation associated with morbidity and mortality in systemic, psychiatric, and age-related inflammatory conditions. Given the growing trend of substance use disorder (SUD) in older adults, and the relationship between inflammation and SUD elevated NLR may serve as a useful inflammatory biomarker of the combined burden of aging and SUD. The present study focused on cocaine use disorder (CUD) to examine if cocaine adds further inflammatory burden among older adults, by comparing NLR values between older adults with CUD and a non-cocaine using, aged-matched, nationally representative sample.

Methods

The dataset included 107 (86% male) participants (aged 50-65 years) with cocaine use disorder. NLR was derived from complete blood count tests by dividing the absolute value of peripheral neutrophil concentration by lymphocyte concentration. For comparison, we extracted data from age-matched adults without CUD using the National Health and Nutrition Examination Survey. Individuals with immunocompromising conditions were excluded (e.g., rheumatoid arthritis and sexually transmitted infections such as HIV). A doubly-robust inverse probability-weighted regression adjustment (IPWRA) propensity score method was used to estimate group differences on NLR while controlling for potential confounding variables (age, gender, race, income, nicotine, marijuana and alcohol use).

Results

The IPWRA model revealed that the CUD sample had significantly elevated NLR in comparison to non-cocaine users, with a moderate effect size (β weight = 0.67).

Conclusion

Although non-specific, NLR represents a readily obtainable inflammatory marker for SUD research. CUD may add further inflammatory burden to aging cocaine users.

Presence of Tat and transactivation response element in spinal fluid despite antiretroviral therapy

OBJECTIVE

The aim of this study was to measure the protein concentration and biological activity of HIV-1 Tat in cerebrospinal fluid (CSF) of individuals on suppressive antiretroviral therapy (ART).

DESIGN

CSF was collected from 68 HIV-positive individuals on ART with plasma viral load less than 40 copies/ml, and from 25 HIV-negative healthy controls. Duration of HIV infection ranged from 4 to more than 30 years.

METHODS

Tat levels in CSF were evaluated by an ELISA. Tat protein and viral RNA were quantified from exosomes isolated from CSF, followed by western blot or quantitative reverse transcription PCR, respectively. Functional activity of Tat was assessed using an LTR transactivation assay.

RESULTS

Tat protein was detected in 36.8% of CSF samples from HIV-positive patients. CSF Tat concentration increased in four out of five individuals after initiation of therapy, indicating that Tat was not inhibited by ART. Similarly, exosomes from 34.4% of CSF samples were strongly positive for Tat protein and/or TAR RNA. Exosomal Tat retained transactivation activity in a CEM-LTR reporter assay in 66.7% of samples assayed, which indicates that over half of the Tat present in CSF is functional. Presence of Tat in CSF was highly associated with previous abuse of psychostimulants (cocaine or amphetamines; P = 0.01) and worse performance in the psychomotor speed (P = 0.04) and information processing (P = 0.02) cognitive domains.

CONCLUSION

Tat and TAR are produced in the central nervous system despite adequate ART and are packaged into CSF exosomes. Tat remains biologically active within this compartment. These studies suggest that Tat may be a quantifiable marker of the viral reservoir and highlight a need for new therapies that directly inhibit Tat.

The effects of cocaine on HIV transcription

Illicit drug users are a high-risk population for infection with the human immunodeficiency virus (HIV). A strong correlation exists between prohibited drug use and an increased rate of HIV transmission. Cocaine stands out as one of the most frequently abused illicit drugs, and its use is correlated with HIV infection and disease progression. The central nervous system (CNS) is a common target for both drugs of abuse and HIV, and cocaine intake further accelerates neuronal injury in HIV patients. Although the high incidence of HIV infection in illicit drug abusers is primarily due to high-risk activities such as needle sharing and unprotected sex, several studies have demonstrated that cocaine enhances the rate of HIV gene expression and replication by activating various signal transduction pathways and downstream transcription factors. In order to generate mature HIV genomic transcript, HIV gene expression has to pass through both the initiation and elongation phases of transcription, which requires discrete transcription factors. In this review, we will provide a detailed analysis of the molecular mechanisms that regulate HIV transcription and discuss how cocaine modulates those mechanisms to upregulate HIV transcription and eventually HIV replication.

Impact of cocaine abuse on HIV pathogenesis

Over 1.2 million people in the United States are infected with the human immunodeficiency virus type 1 (HIV-1). Tremendous progress has been made over the past three decades on many fronts in the prevention and treatment of HIV-1 disease. However, HIV-1 infection is incurable and antiretroviral drugs continue to remain the only effective treatment option for HIV infected patients. Unfortunately, only three out of ten HIV-1 infected individuals in the US have the virus under control. Thus, majority of HIV-1 infected individuals in the US are either unaware of their infection status or not connected/retained to care or are non-adherent to antiretroviral therapy (ART). This national public health crisis, as well as the ongoing global HIV/AIDS pandemic, is further exacerbated by substance abuse, which serves as a powerful cofactor at every stage of HIV/AIDS including transmission, diagnosis, pathogenesis, and treatment. Clinical studies indicate that substance abuse may increase viral load, accelerate disease progression and worsen AIDS-related mortality even among ART-adherent patients. However, confirming a direct causal link between substance abuse and HIV/AIDS in human patients remains a highly challenging endeavor. In this review we will discuss the recent and past developments in clinical and basic science research on the effects of cocaine abuse on HIV-1 pathogenesis.

Immunopathogenesis of HIV infection in cocaine users: role of arachidonic acid

Arachidonic acid (AA) is known to be increased in HIV infected patients and illicit drug users are linked with severity of viral replication, disease progression, and impaired immune functions. Studies have shown that cocaine accelerates HIV infection and disease progression mediated by immune cells. Dendritic cells (DC) are the first line of antigen presentation and defense against immune dysfunction. However, the role of cocaine use in HIV associated acceleration of AA secretion and its metabolites on immature dendritic cells (IDC) has not been elucidated yet. The aim of this study is to elucidate the mechanism of AA metabolites cyclooxygenase-2 (COX-2), prostaglandin E2 synthetase (PGE₂), thromboxane A2 receptor (TBXA₂R), cyclopentenone prostaglandins (CyPG), such as 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2), 14-3-3 ζ/δ and 5-lipoxygenase (5-LOX) mediated induction of IDC immune dysfunctions in cocaine using HIV positive patients. The plasma levels of AA, PGE_2, 15d-PGJ2, 14-3-3 ζ/δ and IDC intracellular COX-2 and 5-LOX expression were assessed in cocaine users, HIV positive patients, HIV positive cocaine users and normal subjects. Results showed that plasma concentration levels of AA, PGE₂ and COX-2, TBXA₂R and 5-LOX in IDCs of HIV positive cocaine users were significantly higher whereas 15d-PGJ2 and 14-3-3 ζ/δ were significantly reduced compared to either HIV positive subjects or cocaine users alone. This report demonstrates that AA metabolites are capable of mediating the accelerative effects of cocaine on HIV infection and disease progression.

Systems-level view of cocaine addiction: the interconnection of the immune and nervous systems

The human body is a complex assembly of physiological systems designed to manage the multidirectional transport of both information and nutrients. An intricate interplay between the nervous, circulatory, and secretory systems is therefore necessary to sustain life, allow delivery of nutrients and therapeutic drugs, and eliminate metabolic waste products and toxins. These systems also provide vulnerable routes for modification by substances of abuse. Addictive substances are, by definition, neurologically active, but as they and their metabolites are spread throughout the body via the nervous, circulatory, respiratory and digestive systems, there is abundant opportunity for interaction with numerous cell and tissue types. Cocaine is one such substance that exerts a broad physiological effect. While a great deal of the research concerning addiction has addressed the neurological effects of cocaine use, only a few studies have been aimed at delineating the role that cocaine plays in various body systems. In this paper, we probe the current research regarding cocaine and the immune system, and map a systems-level view to outline a broader perspective of the biological response to cocaine. Specifically, our overview of the neurological and immunomodulatory effects of the drug will allow a broader perspective of the biological response to cocaine. The focus of this review is on the connection between the nervous and immune systems and the role this connection plays in the long-term complications of cocaine use. By describing the multiplicity of these connections, we hope to inspire detailed investigations into the immunological interplay in cocaine addiction.

Cocaine and HIV-1 interplay in CNS: cellular and molecular mechanisms

Although antiretrovirals are the mainstay of therapy against HIV infection, neurological complications associated with the virus continue to hamper quality of life of the infected individuals. Drugs of abuse in the infected individuals further fuel the epidemic. Epidemiological studies have demonstrated that abuse of cocaine resulted in acceleration of HIV infection and the progression of NeuroAIDS. Cocaine has not only been shown to play a crucial role in promoting virus replication, but also has diverse but often deleterious effects on various cell types of the CNS. In the neuronal system, cocaine exposure results in neuronal toxicity and also potentiates gp120-induced neurotoxicity. In the astroglia and microglia, cocaine exposure leads to up-regulation of pro-inflammatory mediators such as cytokines and chemokines. These in turn, can lead to neuroinflammation and transmission of toxic responses to the neurons. Additionally, cocaine exposure can also lead to leakiness of the blood-brain barrier that manifests as enhanced transmigraiton of leukocytes/monocytes into the CNS. Both in vitro and in vivo studies have provided valuable tools in exploring the role of cocaine in mediating HIV-associated neuropathogenesis. This review summarizes previous studies on the mechanism(s) underlying the interplay of cocaine and HIV as it relates to the CNS.

Rodent models of HAND and drug abuse: exogenous administration of viral protein(s) and cocaine

Humans and chimpanzees are the natural hosts for HIV. Non-human primate models of SIV/SHIV infection in rhesus, cynomologus and pigtail macaques have been used extensively as excellent model systems for pathogenesis and vaccine studies. However, owing to the variability of disease progression in infected macaques, a phenomenon identical to humans, coupled with their prohibitive costs, there exists a critical need for the development of small-animal models in which to study the untoward effects of HIV-1 infection. Owing to the fact that rodents are not the natural permissive hosts for lentiviral infection, development of small animal models for studying virus infection has used strategies that circumvent the steps of viral entry and infection. Such strategies involve overexpression of toxic viral proteins, SCID mice engrafted with the human PBLs or macrophages, and EcoHIV chimeric virus wherein the gp120 of HIV-1 was replaced with the gp80 of the ecotropic murine leukemia virus. Additional strategy that is often used by investigators to study the toxic effect of viral proteins involves direct stereotactic injection of the viral protein(s) into specific brain regions. The present report is a compilation of the applications of direct administration of Tat into the striatum to mimic the effects of the viral neurotoxin in the CNS. Added advantage of this model is that it is also amenable to repeated intraperitoneal cocaine injections, thereby allowing the study of the additive/synergistic effects of both the viral protein and cocaine. Such a model system recapitulates aspects of HAND in the context of drug abuse.

Cocaine and HIV-1 interplay: molecular mechanisms of action and addiction

Human immunodeficiency virus (HIV) infection is now being driven by drug-abusing populations. Epidemiological studies on drug abusers with AIDS link abuse of cocaine, even more than other drugs, to increased incidence of HIV seroprevalence and progression to AIDS. Both cell culture and animal studies demonstrate that cocaine can both potentiate HIV replication and can potentiate HIV proteins to cause enhanced glial cell activation, neurotoxicity, and breakdown of the blood-brain barrier. Based on the ability of both HIV proteins and cocaine to modulate NMDA receptor on neurons, NMDA receptors have been suggested as a common link underlying the crosstalk between drug addiction and HIV infection. While the role of dopamine system as a major target of cocaine cannot be overlooked, recent studies on the role of sigma receptors in mediating the effects of cocaine in both cell and organ systems warrants a deeper understanding of their functional role in the field. In this review, recent findings on the interplay of HIV infection and cocaine abuse and their possible implications in mode of action and/or addiction will be discussed.

Cocaine administration increases CD4/CD8 lymphocyte ratio in peripheral blood despite lymphopenia and elevated corticosterone

The CD4/CD8 lymphocyte ratio in peripheral blood is used in the diagnosis of HIV infection, autoimmune disorders or susceptibility to infections. The present experiment aimed to evaluate the lymphocyte subsets, their distribution and CD4/CD8 ratio in blood after repeated, intravenous administration of cocaine. Adult male Wistar rats received three daily, in 30 min intervals, intravenous infusions of cocaine hydrochloride (5 mg/kg) or saline for 14 consecutive days. After each infusion the locomotor-activating effects of cocaine were assessed. Blood samples were collected 30 min after the last daily infusion on the 1st, 7th and 14th day of treatment. Total leukocyte numbers, percentages of leukocyte subpopulations, and T, B, NK, T CD4+, and T CD8+ lymphocyte subsets, IFN-γ, and plasma corticosterone were determined. Repeated cocaine treatment resulted in an increase in neutrophil numbers and a significant decrease in total leukocyte and lymphocyte numbers involving a significant reduction in numbers of T, B, and NK lymphocyte subsets. T CD4+ and T CD8+ lymphocyte numbers were reduced but with a considerably smaller decrease in T CD4+ number. Cocaine treatment altered proportions between the lymphocyte subsets by decreasing the percentages of T CD8+, B, and NK cells but increasing a percentage of T CD4+ cells. Destabilization in proportions between T CD4+ and T CD8+ was manifested as an elevated CD4/CD8 ratio that occurred despite increased plasma corticosterone and the lymphocytopenia. Cocaine did not affect the concentration of IFN-γ. The results suggest that although cocaine induced lymphopenia, it did not suppress the overall immune activity in terms of the CD4/CD8 ratio.

Cocaine-mediated enhancement of virus replication in macrophages: implications for human immunodeficiency virus-associated dementia

Injection drug use has been recognized as a major risk factor for acquired immunodeficiency syndrome (AIDS) from the outset of the epidemic. Cocaine, one of the most widely abused drugs in the United States, can both impair the functions of macrophages and CD4(+) lymphocytes and also activate human immunodeficiency virus (HIV)-1 expression in these cells. Because the brain is the target organ for both cocaine and HIV, the objective of the present study was to explore the effects of cocaine on virus replication in macrophages, the target cells for the virus in the central nervous system (CNS). Cocaine markedly enhanced virus production in simian human immunodeficiency virus (SHIV)-infected monocyte-derived macrophages (MDMs) and in U1 cells, a chronically infected promonocytic cell line as monitored by enzyme-linked immunosorbent assay (ELISA) and immunocytochemistry. Cocaine treatment also resulted in the activation of nuclear factor (NF)-kappa B and transcriptional activation of the HIV-LTR (long terminal repeat) gag-GFP (green fluorescent protein). Analyses of chemokines in cocaine-treated macrophages by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Luminex assays suggested increased expression of interleukin (IL)-10, a cytokine that is known to promote HIV replication in MDMs. In addition to enhancing IL-10 expression, cocaine also caused an up-regulation of the macrophage activation marker, human leukocyte antigen (HLA)-DR, in MDMs. The synergistic effect of cocaine on virus replication and its enhancement of host activation markers suggest that cocaine functions at multiple pathways to accelerate HIV-associated dementia (HAD).

κ-Opioid Receptor Ligands Inhibit Cocaine-Induced HIV-1 Expression in Microglial Cells

Cocaine abuse has been implicated as a cofactor in human immunodeficiency virus (HIV)-1-associated dementia (HAD). In this study, we tested the hypothesis that exposure of microglial cells, the resident macrophages of the brain, to cocaine would potentiate HIV-1 expression. Because kappa-opioid receptor (KOR) agonists have been shown to suppress neurochemical and neurobehavioral responses to cocaine and to inhibit HIV-1 expression in microglial cell cultures, we also postulated that KOR ligands would inhibit cocaine-induced potentiation of HIV-1 expression. Human microglial cells were infected with HIV-1(SF162), an R5 isolate, and viral expression was quantified by measurement of p24 antigen in culture supernatants. Treatment of microglia with the KOR agonists trans-(+/-)-3,4-dichlor-N-methyl-N-(2[1-pyrrolidnyl])benzeneacetamide methanesulfonate and 8-carboxamidocyclazocine inhibited viral expression (maximal suppression of 42 and 48%, respectively). Consistent with the hypotheses, treatment of microglia with cocaine promoted HIV-1 expression (maximal enhancement of 54%), and pretreatment of microglia with these KOR agonists as well as with the KOR-selective antagonist nor-binaltorphimine abrogated cocaine-induced potentiation of viral expression. Results of flow cytometry studies suggested that the mechanism whereby KOR ligands inhibit cocaine's stimulatory effect on viral expression involves the suppression of cocaine-induced activation of extracellular signal-regulated kinase1/2, thereby blunting cocaine-enhanced up-regulation of the HIV-1 entry chemokine coreceptor CCR5. The findings of this study suggest that in addition to its neurotoxic effects, cocaine could foster development of HAD by potentiating viral expression in the brain and that this phenomenon is inhibited by KOR ligands.

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.

Chronic methamphetamine exposure alters immune function in normal and retrovirus-infected mice

Methamphetamine (MA) abuse represents a growing problem in the USA with an increase of sudden death. To evaluate the immune function alterations due to chronic methamphetamine use, we examined C57BL/C mice with LP-BM5 retrovirus infection plus methamphetamine exposure. Mice were randomly assigned to the following groups: placebo, placebo retrovirus-infected, uninfected MA treated and retrovirus-infected MA treated. Placebo, MA-treated groups were intraperitoneally injected with saline, MA, respectively, with a gradually increasing dose from 15 to 40 mg/kg for 12 weeks (5 days/week). Con A- and LPS-induced mitogenesis of splenocytes, cytokine production by splenocytes culture and lipid peroxides in the liver were measured. Heart tissue histopathology was analyzed in all the groups with murine cytomegalovirus (CMV) superinfection. Our data showed that MA treatment significantly decreased production of IL-2 and interferon gamma (IFN-gamma) in uninfected mice but did not further suppress the reduced Th1 cytokines in retrovirus-infected mice. There were no significant effects on cytokines IL-4 and IL-6. However, tumor necrosis factor (TNF-alpha) was significantly increased in both uninfected and infected mice due to MA treatment. Lipid peroxides in liver were significantly increased both in uninfected and retrovirus-infected mice due to MA exposure. Vitamin E levels in liver were significantly decreased in uninfected mice due to MA treatment. CMV superinfection greatly increased the cardiac lesions in retrovirus-infected mice while no significant histopathology changes were detected due to MA treatment. Our data suggest that MA has immunomodulation activity, suppressing Th1 cytokine production and enhancing some Th2 cytokine secretion, as well as increasing lipid peroxides in uninfected mice. The interaction between LP-BM5 and MA remains unclear.

Embryonic "binge" cocaine exposure alters neural-immune and neural-endocrine interactions in young chickens: involvement of serotonin(2) receptors

As part of our characterization of the developmental consequences of prenatal cocaine exposure, cocaine was injected into eggs containing viable chicken embryos on embryonic day (E) 18 and the fever response to the endotoxin lipopolysaccharide (LPS) and a delayed-type hypersensitivity response to phytohemagglutinin (PHA) were assessed postnatally. E18 cocaine exposure did not affect basal body temperature. LPS induced a fever in the chicks at 4 h post-injection on post-hatch day (D) 4 and 2 h post-injection on D24. E18 cocaine exposure suppressed the peak LPS-induced fever by 50% at both ages. E18 cocaine exposure also suppressed the hypersensitivity reaction to an intradermal injection of PHA on D17, while having no effect on the response to a saline injection. To determine the importance of serotonin(2) (5-HT(2)) receptors in the developmental toxicity of cocaine, varying doses of the 5-HT(2) antagonist ritanserin were injected on E17 followed by cocaine on E18. Ritanserin, like cocaine, did not alter basal temperature, but it dose-relatedly attenuated or blocked cocaine's effect on LPS-induced fever on both D4 and D24. Ritanserin pretreatment was also able to block the blunted isolation stress response seen in D16 chicks following E18 cocaine exposure. Thus, late prenatal cocaine exposure significantly alters adaptive fever and hypersensitivity responses, and embryonic 5-HT(2) receptors played a mediating role in the fever effect.

Cocaine injection and coxsackievirus B3 infection increase heart disease during murine AIDS

Coxsackievirus initiates myocarditis especially in the immunologically deficient or immature. To test whether Coxsackievirus B3 (CVB3) induced pronounced cardiomyopathy during severe immune dysfunction of murine AIDS, female C57BL/6 mice were infected with LP-BM5 retrovirus and superinfected with CVB3. Some were also injected daily with cocaine hydrochloride in 0.9% saline solution (30 mg/kg) intraperitoneally, because cocaine also suppresses cellular immune response. Heart tissue was analyzed histopathologically. Mice experiencing concurrent retrovirus and Coxsackievirus infection had a high degree of cardiac lesions consistent with myopathy compared with findings in uninfected animals (p <.05). Cocaine injection during murine retrovirus infection greatly exacerbated the pathogenesis of Coxsackievirus infection. C57BL/6 mice, essentially resistant to Coxsackievirus-induced cardiomyopathy, became susceptible during the immune dysfunction in murine AIDS. This suggests that retrovirus infection causes conditions favoring Coxsackie-induced cardiac lesions. Interleukin (IL)-2 and IL-4 expression by splenocytes from the dually infected retrovirus and Coxsackievirus group showed no significant differences when the animals were also cocaine treated. However tumor necrosis factor TNF-alpha production was significantly decreased in dually infected retrovirus + Coxsackievirus mice treated with cocaine, compared with findings in various controls (p <.05).

Cocaine effects on immunocompetent cells: an observation of in vitro cocaine exposure

This study investigated in vitro effects of cocaine on the function of T and B lymphocytes, natural killer cells and macrophages in a mouse model. In mature C57BL/6J mice (60-90 day-old), splenocytes were cultured with cocaine at different concentrations ranging from 4 to 64 microg/ml for 24 h. The exposure to cocaine in vitro was found to affect (1) T cell function, with reduced responses to stimulation of Con-A, PHA and Interleukin 2, and decreased production of gamma-IFN; (2) B cell function, with reduced response to LPS; (3) natural killer cell function, with attenuated killing capacity; (4) monocyte-macrophage function, with decreased ability to inhibit the growth of tumor cells. The results of the study indicated a direct cocaine effect on four major immune competent cells, and the generally suppressive effects of in vitro cocaine exposure may be related to its in vivo action on the immune system.

Histopathologic and molecular alterations in bronchial epithelium in habitual smokers of marijuana, cocaine, and/or tobacco

BACKGROUND

Tobacco smoking has been observed to cause molecular alterations in bronchial epithelium that antedate the development of lung carcinoma. The rising prevalence of marijuana and cocaine use among young adults in the United States prompted us to investigate whether similar molecular and histopathologic alterations occur in habitual smokers of marijuana and/or cocaine who may or may not also smoke tobacco.

METHODS

Bronchoscopy was performed in 104 healthy volunteer subjects, including 28 nonsmokers and 76 smokers of one or more of the following substances: marijuana, tobacco, and/or cocaine. Bronchial mucosa biopsy specimens and brushings were analyzed for histopathologic changes, for immunohistopathologic expression of intermediate or surrogate end-point markers that are linked to an increased risk of cancer (Ki-67 [a marker of cell proliferation], epidermal growth factor receptor, p53, Her-2/neu [also known as erbB-2 and ERBB2], globular actin, and abnormal DNA ploidy). Reported P values are two-sided.

RESULTS

Smokers of any one substance or of two or more substances exhibited more alterations than nonsmokers in five to nine of the 10 histopathologic parameters investigated (all P < .05), and they exhibited more molecular abnormalities than nonsmokers. Differences between smokers and nonsmokers were statistically significant (all P < or = .01) for Ki-67, epidermal growth factor receptor, globular actin, and DNA ploidy. There was general agreement between the presence of molecular abnormalities and histopathologic alterations; however, when disagreement occurred, the molecular abnormalities (e.g., Ki-67 and epidermal growth factor receptor) were more frequently altered (all P < or = .01).

CONCLUSIONS

These findings suggest that smoking marijuana and/or cocaine, like tobacco smoking, exerts field cancerization effects on bronchial epithelium, which may place smokers of these substances at increased risk for the subsequent development of lung cancer.

Acute and chronic effects of cocaine on the immune system and the possible link to AIDS

The pathogenesis of AIDS is a complex and prolonged process that is affected by a variety of cofactors, including the abuse of both intravenous and smoked (crack) cocaine. The exact mechanisms by which cocaine facilitates this disease are yet to be proven, but likely include a combination of increased risk due to cocaine-related social behaviours, a wide-ranging capacity for cocaine to suppress the immune system, and an effect of cocaine on the infectivity and replication of HIV. While sometimes contradictory, both human and animal studies document that cocaine alters the function of natural killer (NK) cells, T cells, neutrophils and macrophages, and alters the ability of these cells to secrete immunoregulatory cytokines. In addition to these effects on the immune system, cocaine also enhances the infectivity and/or replication of HIV when tested using human cells in vitro.

Cocaine inhibits human endothelial cell IL-8 production: the role of transforming growth factor-beta

Cocaine use is associated with modulation of a broad range of biological functions including the capacity to influence cytokine production in murine and human immunoeffector cells. Little is known, however, regarding the effects of cocaine on endothelial cell cytokine production. Because the vascular endothelium actively participates in acute and chronic inflammatory responses and interleukin-8 (IL-8) is one of the key cytokines involved in the inflammatory process, modification of the production of IL-8 by vascular endothelial cells may interfere with the host response to infection or tissue injury. We investigated the effect of cocaine on endothelial cell IL-8 production. Conditioned supernatant from EA.hy 926 cells were evaluated by ELISA following in vitro cocaine exposure. Cocaine decreased IL-8 production in a dose-responsive manner, and this reduction correlated with down-regulation of IL-8 mRNA expression. Cocaine also increased the production of TGF-beta by EA.hy 926 cells and anti-TGF-beta abrogated the cocaine-mediated decrement of IL-8 production, indicating that cocaine down-regulates endothelial IL-8 production by increasing TGF-beta. Our findings suggest that the immunomodulatory effects of cocaine may be mediated, in part, by modification of endothelial-derived cytokine production.

Suppression of splenic T lymphocyte proliferation by acute cocaine administration

We have recently demonstrated that cocaine administration has a limited effect on mitogen-stimulated T lymphocyte proliferation. The present study investigated the effect of cocaine on splenic T cell response to alloantigens. Rats received intraperitoneal injections of cocaine HCI, and splenocytes were isolated either thirty minutes or three hours post-administration. In the thirty minute exposure group, cocaine at 10.0 and 25.0 mg/Kg/B.Wt. suppressed (p<0.05) T cell proliferation in mixed lymphocyte cultures. Compared to control data, proliferation was decreased by 46.6% and 56.4%, respectively. However, this effect was not as pronounced in cells isolated three hours post-administration, indicating a transient inhibition of T cell function by cocaine. The decrease in splenic T cell proliferation in response to alloantigens in the thirty minute exposure group did not reflect alterations in calcium influx or IL-2 production. Although this study did not ascertain the exact mechanism of inhibition, these results demonstrate that short-term cocaine exposure can alter T cell reactivity to alloantigens, suggesting a reduction in the functional status of these cells.

In vitro proliferative response of human peripheral blood mononuclear cells to concanavalin A

The proliferation response of human peripheral blood mononuclear cells (PBMC) to concanavalin A (con A) was tested in a medium with or without addition of fetal calf serum (FCS) or a serum substitute. The time profile of the proliferative response of PBMC to con A was different in cells cultured in a medium supplemented with or without FCS. This different pattern occurred for the con A-induced DNA-synthesis as well as for the RNA- or protein-synthesis. The peak proliferation rate and the stimulation index of proliferation of human PBMC to con A was also higher when the cells were cultured in a medium with 10% FCS compared to cells cultured in a FCS-free medium. Substitution of the fetal calf serum by a serum substitute even induced a profound inhibition of the de novo synthesis of DNA in human PBMC. The results indicate that a lymphocyte proliferation response to con A can still be obtained in a culture medium where no FCS was added, although a weaker stimulation occurred in comparison to a culture medium with FCS. However, addition of a serum substitute caused a marked inhibition of the lymphocyte proliferation rate.

Cocaine/sex type effects on T lymphocytes: a preliminary report

The influence of gender on the effects of cocaine (5 or 40 mg/kg) on immune function of sexually immature (35-day-old) C57BL/6J mice was assessed. The proliferation of T cells in thymus and spleen stimulated with phytohemagglutinin (PHA) and concanavalin-A(Con-A) was determined by 3H thymidine incorporation 24 hours after cocaine injections. The drug produced a dose-dependent reduction (25-51%) of Con-A and PHA-stimulated T cell proliferation in thymus from both male and female mice. Additionally, the impairment occurred at a lower cocaine dose for female than for male mice when the T cells were challenged with PHA. Under the experimental conditions, cocaine did not alter weights or cell numbers of thymus and spleen or T cell proliferation in spleen.

Effect of cocaine administration on concanavalin A-stimulated T-lymphocyte proliferation in rats

There is a high prevalence of cocaine abuse among Americans. There is an increasing concern over the rise of infectious diseases among individuals in this drug abuse population. This concern may be due, at least in part, to a direct effect of cocaine on the immune system. The present study investigated the effects of cocaine administration on optimal mitogen-induced proliferation in rats. Following cocaine administration, splenic lymphocytes were isolated and T-lymphocytes incubated with concanavalin A. When T-lymphocytes were isolated 30 minutes following cocaine administration, a significant enhancement of optimal mitogen-stimulated proliferation was observed at 0.1 mg/Kg cocaine. Enhancement of proliferation was seen 20 hours following cocaine administration at 0.1, 1.0 and 10 mg/Kg. However, these results were not statistically significant. Cocaine administered once daily for seven days had no effect on mitogen-induced proliferation. These results suggest that cocaine administration has a limited effect on optimal mitogen-stimulated proliferation.

Stimulatory effects of cocaine and its metabolites on IM-9 human B-lymphoblastoid cells

This study examined the effect of cocaine and its metabolites benzoylecgonine, norcocaine, and cocaethylene on human B-cell proliferation using IM-9 cells. Cells were incubated with 0.01-10 micrograms/ml of cocaine or metabolite in serum-free medium or medium containing 2% FBS for 24 and 48 h, and [3H] thymidine incorporation into DNA was measured using liquid scintillation counting. Results showed incubation with cocaine and metabolites significantly increased IM-9 cell proliferation. With cocaine, maximal stimulation of 148% (compared to drug-free control) occurred at 1.0 micrograms/ml in serum-free medium at 48 h. Benzoylecgonine and norcocaine showed maximal stimulation at 0.1 micrograms/ml with 170% and 150% stimulation, respectively. Cocaethylene showed maximal stimulation of 146% at 10 micrograms/ml. Drug stability was monitored under incubation conditions using high-performance liquid chromatography (HPLC). We have shown that cocaine and its major metabolites have an immunomodulatory effect on B-cell proliferation at concentrations equivalent to serum levels produced during cocaine use in humans. Since the cocaine metabolites also show an immunomodulatory effect, the immune consequences of cocaine use may be significantly prolonged.

Cocaine blunts human CD4+ cell activation

Cocaine is reported to be immunotoxic. The biochemical mechanisms responsible for the immunopharmacological outcomes of cocaine in vivo and in vitro remain, however, to be fully elucidated. Our experimental data confirm that exposure of normal human T cells to micromolar concentrations of cocaine modulates T-cell responses to stimulation by a variety of stimuli, and indicate that cocaine impairs early activation events during CD4+ but not CD4- T-cell stimulation. Pre-incubation of enriched CD4+ T-cell subpopulations that express the homing receptor CD62L with nanomolar concentrations of the endogenous opioid peptide beta-endorphin leads to a more severe impairment of activation than that noted following pre-incubation with micromolar concentrations of cocaine alone. These findings begin to elucidate the molecular and cellular mechanisms of the immunopathology of cocaine. Our data support the proposition that cocaine abuse may place cocaine-abuser HIV-seropositive individuals at increased risk of opportunistic infections.

Differential effects of short-term or prolonged cocaine exposure on peripheral blood cells in mice

The effects of cocaine on the number of murine peripheral blood cells and on phenotypic expression of lymphocyte subsets were examined using different regimens of drug exposure. Cocaine administered to mice for 7 consecutive days at 1 and 10 mg/kg/day reduced the absolute number of circulating white blood cells and the relative number of cells stained as lymphocytes, polymorphonuclear cells and monocytes. Cocaine did not modify the relative proportion between lymphocytes, polymorphonuclear cells and monocytes. Parallely, there were no changes in the percentage of circulating CD4+ and CD8+ lymphocytes, while the number of natural killer cells increased. In sharp contrast, we didn't observe any significant change in peripheral blood cells after 30 days of consecutive drug administrations.