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Background: Little is known about chronic cannabis smoking-associated oral microbiome and its effects on central nervous system (CNS) functions., Methods: In the current study, we have analyzed the saliva microbiome in individuals who chronically smoked cannabis with cannabis use disorder (n = 16) and in non-smoking controls (n = 27). The saliva microbiome was analyzed using microbial 16S rRNA sequencing. To investigate the function of cannabis use-associated oral microbiome, mice were orally inoculated with live Actinomyces meyeri, Actinomyces odontolyticus, or Neisseria elongata twice per week for six months, which mimicked human conditions., Findings: We found that cannabis smoking in humans was associated with oral microbial dysbiosis. The most increased oral bacteria were Streptococcus and Actinomyces genus and the most decreased bacteria were Neisseria genus in chronic cannabis smokers compared to those in non-smokers. Among the distinct species bacteria in cannabis smokers, the enrichment of Actinomyces meyeri was inversely associated with the age of first cannabis smoking. Strikingly, oral exposure of Actinomyces meyeri, an oral pathobiont, but not the other two control bacteria, decreased global activity, increased macrophage infiltration, and increased β-amyloid 42 protein production in the mouse brains., Interpretation: This is the first study to reveal that long-term oral cannabis exposure is associated oral enrichment of Actinomyces meyeri and its contributions to CNS abnormalities., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2021. Published by Elsevier B.V.)

Importance: Neuropsychiatric manifestations of COVID-19 have been reported in the pediatric population., Objective: To determine whether anti-SARS-CoV-2 and autoreactive antibodies are present in the cerebrospinal fluid (CSF) of pediatric patients with COVID-19 and subacute neuropsychiatric dysfunction., Design, Setting, and Participants: This case series includes 3 patients with recent SARS-CoV-2 infection as confirmed by reverse transcriptase-polymerase chain reaction or IgG serology with recent exposure history who were hospitalized at the University of California, San Francisco Benioff Children's Hospital and for whom a neurology consultation was requested over a 5-month period in 2020. During this period, 18 total children were hospitalized and tested positive for acute SARS-CoV-2 infection by reverse transcriptase-polymerase chain reaction or rapid antigen test., Main Outcomes and Measures: Detection and characterization of CSF anti-SARS-CoV-2 IgG and antineural antibodies., Results: Of 3 included teenaged patients, 2 patients had intrathecal anti-SARS-CoV-2 antibodies. CSF IgG from these 2 patients also indicated antineural autoantibodies on anatomic immunostaining. Autoantibodies targeting transcription factor 4 (TCF4) in 1 patient who appeared to have a robust response to immunotherapy were also validated., Conclusions and Relevance: Pediatric patients with COVID-19 and prominent subacute neuropsychiatric symptoms, ranging from severe anxiety to delusional psychosis, may have anti-SARS-CoV-2 and antineural antibodies in their CSF and may respond to immunotherapy.

Cannabis, or marijuana, comprises many compounds with varying effects. It has become a treatment option for chronic diseases and debilitating symptoms, and evidence suggests that it has immunomodulatory and antiinflammatory properties. Transplant centers are more frequently facing issues about cannabis, as indications and legalization expand. As of February 2020, 33 states and the District of Columbia have legalized medical cannabis, and 14 have legalized recreational cannabis. Moreover, 8 states have passed legislation prohibiting the denial of transplant listing solely based on cannabis use. Studies demonstrate the potential for significant pharmacokinetic and pharmacodynamic interactions between cannabis and immunosuppression. Additionally, safety concerns include increased risk of myocardial infarction, ischemic stroke, tachyarrhythmias, malignancy, neurocognitive deficits, psychosis, other neuropsychiatric disorders, cannabis use disorder, respiratory symptoms, and infection. A recent retrospective database study found a negative association between documented cannabis use disorder and graft survival, but little additional evidence exists evaluating this relationship. In the absence of robust clinical data, transplant centers need a clear, reasoned, and systematic approach to cannabis. The results of our national survey, unfortunately, found little consensus among institutions. As both recreational and medicinal cannabis become more ubiquitous nationwide, transplant centers will need to develop comprehensive policies to address its use., Competing Interests: L.J.B. has served on an advisory board for Veloxis Pharmaceuticals and currently serves on their Speaker’s Bureau. The other authors declare no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Background : Smoking causes widespread epigenetic changes that have been linked with an increased risk of smoking-associated diseases and elevated mortality. Of particular interest are changes in the level of T cells expressing G-protein-coupled receptor 15 (GPR15), a chemokine receptor linked with multiple autoimmune diseases, including inflammatory bowel disease, multiple sclerosis and psoriasis. Accordingly, a better understanding of the mechanisms by which smoking influences variation in the GPR15 + helper T cell subpopulation is of potential interest. Methods : In the current study, we used flow cytometry and digital PCR assays to measure the GPR15 + CD3 + CD4 + populations in peripheral blood from a cohort of n = 62 primarily African American young adults (aged 27-35 years) with a high rate of tobacco and cannabis use. Res u l ts: We demonstrated that self-reported tobacco and cannabis smoking predict GPR15 + CD3 + CD4 + helper T cell levels using linear regression models. Further, we demonstrated that methylation of two candidate CpGs, cg19859270, located in GPR15 , and cg05575921, located in the gene Aryl Hydrocarbon Receptor Repressor ( AHRR ), were both significant predictors of GPR15 + CD3 + CD4 + cell levels, mediating the relationship between smoking habits and increases in GPR15 + CD3 + CD4 + cells. As hypothesized, the interaction between cg05575921 and cg19859270 was also significant, indicating that low cg05575921 methylation was more strongly predictive of GPR15 + CD3 + CD4 + cell levels for those who also had lower cg19859270 methylation. Conclusions : Smoking leads changes in two CpGs, cg05575921 and cg19859270, that mediate 38.5% of the relationship between tobacco and cannabis smoking and increased GPR15 + T h levels in this sample. The impact of cg19859270 in amplifying the association between cg05575921 and increased GPR15 + T h levels is of potential theoretical interest given the possibility that it reflects a permissive interaction between different parts of the adaptive immune system., Competing Interests: The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. The use of DNA methylation to assess smoking status is covered by US patent 8,637,652 and other pending claims. Dr. Philibert is a potential royalty recipient on those intellectual right claims. Dr. Philibert is also an officer and stockholder of Behavioral Diagnostics. (www.bdmethylation.com).

Exposure to Δ 9 -tetrahydrocannabinol (THC) in vitro and in animal models can significantly impair the differentiation, activation and function of dendritic cells, T cells and B cells. However, studies directly assessing the impact of marijuana smoking on human immunity are lacking. A prospective study of immune responses to a standard hepatitis B vaccination was therefore carried out in a matched cohort of 9 marijuana smokers (MS) and 9 nonsmokers (NS). In addition to their regular marijuana use, MS smoked four marijuana cigarettes in a monitored setting on the day of each vaccination. Blood samples were collected over time to assess the development of hepatitis B-specific immunity. The majority of subjects from both the NS (8) and MS (6) groups developed positive hepatitis B surface antibody titers (>10 IU/L) and of these 6 NS and 5 MS were classified as high antibody (good) responders (>100 IU/L). The development of a good response correlated with the presence of hepatitis B-specific T cell proliferation and cytokine production, resulting in a clear distinction regarding the immune status of good responders versus non-responders. However, even though there were slighter more non-responders in the MS cohort, there were no significant differences between MS and NS with respect to peripheral blood cell phenotypes or vaccination-related changes in hepatitis B responses. While a larger cohort may be required to rule out a small suppressive effect, our findings do not suggest that habitual marijuana smoking exerts a major impact on the development of systemic immunity to hepatitis B vaccination.

It is unknown how lifetime marijuana use affects different proinflammatory cytokines. The purpose of the current study is to explore potential differential effects of lifetime marijuana use on interleukin-1 alpha (IL-1α) and tumor necrosis factor (TNF) in a community based sample. Participants included 168 African American adults (51 % female, median age = 47 years). Upon study entry, blood was drawn and the participants completed questions regarding illicit drug use history whose answers were used to create three groups: lifetime non-drug users (n = 77), lifetime marijuana only users (n = 46) and lifetime marijuana and other drug users (n = 45). In the presence of demographic and physiological covariates, non-drug users were approximately two times more likely (AOR 2.73, CI 1.18, 6.31; p = .03) to have higher TNF levels than marijuana only users. Drug use was not associated with IL-1α. The influence of marijuana may be selective in nature, potentially localizing around innate immunity and the induction of cellular death.

Tobacco smoking is a well-recognized risk factor for Legionnaires disease. However, it may be potentiated by cannabis use, as there is strong evidence that Δ(9)-tetrahydrocannabinol impairs immune functions in vitro and in vivo. We report herein two out of three cases of severe Legionnaires disease in three men with no overt comorbid illnesses, aged 38, 28, and 48 years, respectively. All of them were heavy cigarette and cannabis smokers.

Purpose of Review: Cannabis is currently the most widely used illicit substance in the world. The issue of how to handle transplant candidates with active use of cannabis is a commonly encountered one for transplant-selection committees., Recent Findings: Correlates of marijuana use include increased risk of use of other illicit substances, increased risk of affective disorders and psychosis, as well as impaired cognition and motor skills. Risk of fungal infections and possible effects on cellular immunity that may increase cancer risk have also been reported. Reliability of laboratory testing for cannabis is discussed. False-negatives may occur with stealth peroxidases and false-positives with efavirenz (Sustiva). Photometric immunoassay (EMITS) has a 3% false-positive rate. Using a cutoff point of 20 ng/ml with confirmation via GC/MS will give a 'virtually 100% reliable accuracy' in detecting cannabis abuse., Summary: Guidelines on management of the problem should be based on objective medical evidence on the health effects of marijuana, as well as on the implications in the transplant setting where medical urgency can drive medical decision-making. A recent survey of 16 academic transplant centers showed little consensus on guidelines for length of abstinence prior to listing candidates for transplantation.

Human alveolar macrophages (AMs) were recovered from the lungs of healthy nonsmokers (NS) or smokers of tobacco (TS), marijuana (MS), or crack cocaine (CS) and challenged in vitro with Staphylococcus aureus. AMs from NS and TS exhibited potent antibacterial activity that correlated with the production of nitric oxide (NO) and induction of NO synthase without the requirement for priming with exogenous cytokines. In contrast, AMs from MS and CS exhibited minimal antibacterial activity and failed to produce NO unless primed with additional cytokines. These results confirm that NO plays a significant role as an effector molecule used by normal human AMs, but this capacity is suppressed in AMs from MS and CS because of a lack of intrinsic cytokine priming.

We studied, using RT-PCR, the relative expression of cannabinoid receptor (CBR) mRNA in peripheral blood mononuclear cells (PBMC) from different donor groups. Cells from normal donors expressed a CB2 mRNA level threefold higher than CB1 across all age, gender or ethnicity groups, and amplicons were of the same size in all donors. However, cells from marijuana users expressed higher levels of CBR mRNA, but with a preserved CB1/CB2 ratio of 1:3. CBR gene products were also studied following short-term mitogen activation in vitro. CB1 expression decreased following mitogen stimulation when compared to the time-matched medium only cells while the expression of CB2 mRNA remained unchanged. These studies suggest that marijuana smoking and immune activation can alter the basal levels of CB1 and CB2 in PBMCs.

Use of marijuana and cocaine is on the rise in the United States. Although pulmonary toxicity from these drugs has occasionally been reported, little is known about their effects on the lung microenvironment. We evaluated the function of alveolar macrophages (AMs) recovered from the lungs of nonsmokers and habitual smokers of either tobacco, marijuana, or crack cocaine. AMs recovered from marijuana smokers were deficient in their ability to phagocytose Staphylococcus aureus (p < 0.01). AMs from marijuana smokers and from cocaine users were also severely limited in their ability to kill both bacteria and tumor cells (p < 0.01). Studies using NG-monomethyl-L-arginine monoacetate, an inhibitor of nitric oxide synthase, suggest that AMs from nonsmokers and tobacco smokers were able to use nitric oxide as an antibacterial effector molecule, while AMs from smokers of marijuana and cocaine were not. Finally, AMs from marijuana smokers, but not from smokers of tobacco or cocaine, produced less than normal amounts of tumor necrosis factor-alpha, granulocyte-macrophage colony-stimulating factor, and interleukin-6 when stimulated in culture with lipopolysaccharide. In contrast, the production of transforming growth factor-beta, an immunosuppressive cytokine, was similar in all groups. These findings indicate that habitual exposure of the lung to either marijuana or cocaine impairs the function and/or cytokine production of AMs. The ultimate outcome of these effects may be an enhanced susceptibility to infectious disease, cancer, and AIDS.

Therapeutic observations suggest that azidothymidine (AZT)-resistant HIV+/AIDS patients are frequently offered AZT/dideoxycytidine (DDC) or dideoxyinosine (DDI) therapy. The latter therapies have been associated with the development of acute pancreatitis. During the initial portion of this study, when patients reported limiting ethanol consumption, an increase in CD4+, a decrease in amylase, and a decrease in lipase was observed in patients on DDI monotherapy. Marinol/marijuana usage was associated with depressed CD4+ counts and elevated amylase levels within the DDI subgroup. The purpose of this study was to follow these patients over 1 year and compare clinical indicators of pancreatitis and HIV progression. After 1 year, the remaining 56 patients were reexamined in the follow-up portion for clinical indicators of HIV disease progression and pancreatoxic/hepatotoxic effects. Those in the AZT group, who remained on this therapy throughout the year, had significantly increased amylase values from 55.3 to 69.3 IU/liter (p < 0.05). In the AZT/DDC group, those who remained on combination therapy throughout the year, 4 of the 5 clinical indicators of disease progression changed. Amylase, ALT, and AST all increased significantly from 55.2 to 77.8 IU/liter (p < 0.01), from 38.0 to 92.3 IU/liter (p < 0.05), and from 55.2 to 97.0 IU/liter (p < 0.05), respectively. Lipase levels decreased significantly (106.0 to 74.6 IU/liter, p < 0.05). The most remarkable changes occurred in the AZT/DDC group (who reduced ethanol consumption), wherein clinical indicators of pancreatitis and liver dysfunction declined, including amylase (65.0 to 20.0 IU/liter, p < 0.05), ALT (350.0 to 100.0 IU/liter, p < 0.01), and AST (240.0 to 95.0 IU/liter, p < 0.01). No significant changes were noted in the DDI or AZT groups. Marinol/marijuana use was associated with declining health status in both the AZT and AZT/DDC groups. In contrast, all clinical indicators of pancreatitis improved in the DDI patients who utilized Marinol/marijuana, including amylase (-34%), lipase (-30.8%), ALT (-21.4%), and AST (-20.1%). This paired follow-up study suggests that HIV+/AIDS patients on antiretroviral therapies should restrict their ethanol consumption. In HIV+/AIDS patients with the lowest CD4+ counts (those on DDI monotherapy), utilization of Marinol/marijuana does not seem to have a deleterious impact.

Despite the fairly large literature that developed during the past 15 years or so, the effect of cannabinoids on the immune system is still unsettled. The evidence has been contradictory and is more supportive of some degree of immunosuppression only when one considers in vitro studies. These have been seriously flawed by the very high concentrations of drug used to produce immunosuppression and by the lack of comparisons with other membrane-active drugs. The closer that experimental studies have been to actual clinical situations, the less compelling has been the evidence. Although the topic was of great interest during the 1970's, as indicated by the preponderance of the references from that period, interest has waned during the present decade. This waning of interest suggests that perhaps most investigators feel that this line of inquiry will not be rewarding. The AIDS epidemic has also diverted the attention of immunologists to the far more serious problem of the truly devastating effects a retrovirus can have on a portion of the immune system. The relationship between the use of social drugs and the development of clinical manifestations of AIDS has been of some interest, however. Persons infected with the virus but not diagnosed as AIDS have been told to avoid the use of marijuana and/or alcohol. This advice may be reasonable as a general health measure, but direct evidence that heeding this warning will prevent the ultimate damage to the immune system is totally lacking.