Role of T and B lymphocyte cannabinoid type 1 and 2 receptors in major depression and suicidal behaviours

The endocannabinoid system in cancer biology: a mini-review of mechanisms and therapeutic potential

The Endocannabinoid System (ECS) plays a critical role in maintaining physiological homeostasis, influencing a range of processes such as neuroprotection, inflammation, energy metabolism, and immune responses. Comprising cannabinoid receptors (CB1 and CB2), endogenous ligands (endocannabinoids), and the enzymes responsible for their synthesis and degradation, the ECS has attracted increasing attention in cancer research. Cannabinoid receptor activation has been associated with the regulation of cancer-related processes, including cell proliferation, apoptosis, and angiogenesis, suggesting that the ECS may have a role in tumor progression and cancer treatment. Preclinical studies have shown that cannabinoids, through their interaction with CB1 and CB2 receptors, can inhibit tumor cell growth, induce programmed cell death, and suppress the formation of new blood vessels in various cancer models. Despite these encouraging findings, the clinical translation of ECS-targeted therapies remains in its early stages. The complexity of tumor heterogeneity, the variability in patient responses, and the challenges associated with the pharmacokinetics of cannabinoids are significant obstacles to the broader application of these findings in clinical settings. This review provides an overview of the current understanding of the ECS's involvement in cancer biology, focusing on key mechanisms by which it may influence carcinogenesis. Additionally, we discuss the therapeutic potential of targeting the ECS in cancer treatment, while highlighting the limitations and uncertainties that need to be addressed through ongoing research.

A comprehensive review of the multifaceted role of cannabinoid receptor type 2 in neurodegenerative and neuropsychiatric disorders

Research carried out during the last 30 years since the first identification of CB2r in 1993 has changed the landscape of this receptor's role and therapeutic utility. Initially, studies focused on elucidating the role of CB2r at the periphery since it was first characterized in spleen and lymphocytes. Later, CB2r was found in the brain not only under pathological conditions but also under basal conditions. It is now known that this receptor is expressed in different brain regions and different cell types, including neurons and microglia. Experimental studies have provided robust evidence that CB2r is involved in the modulation of the immune system, neuroinflammation, oxidative stress and neuroprotection. Besides, CB2r mediated the response to stress, anxiety, and depression. Also, CB2r plays a relevant role in modulating the reinforcing properties of different drugs of abuse, including alcohol, nicotine and cocaine. In this review, we summarize the cumulative knowledge regarding the immunomodulatory, anti-inflammatory, antioxidant, and neuroprotective properties of CB2r against the development of neurodegenerative diseases. Indeed, we cover the anxiolytic and antidepressant potential of CB2r, which raises the therapeutic interest of this receptor in different psychiatric diseases associated with anxiety and depression. Finally, we discuss the involvement of CB2r in the regulation of drug addiction. A better understanding of the properties of CB2r is essential for the pharmacological development of this receptor in different neurodegenerative, psychiatric, and addictive disorders.

Skull bone marrow and skull meninges channels: redefining the landscape of central nervous system immune surveillance

The understanding of neuroimmune function has evolved from concepts of immune privilege and protection to a new stage of immune interaction. The discovery of skull meninges channels (SMCs) has opened new avenues for understanding central nervous system (CNS) immunity. Here, we characterize skull bone marrow and SMCs by detailing the anatomical structures adjacent to the skull, the differences between skull and peripheral bone marrow, mainstream animal processing methods, and the role of skull bone marrow in monitoring various CNS diseases. Additionally, we highlight several unresolved issues based on current research findings, aiming to guide future research directions.

Anti-inflammatory effects of phytocannabinoids and terpenes on inflamed Tregs and Th17 cells in vitro

AIMS

Phytocannabinoids and terpenes from Cannabis sativa have demonstrated limited anti-inflammatory and analgesic effects in several inflammatory conditions. In the current study, we test the hypothesis that phytocannabinoids exert immunomodulatory effects in vitro by decreasing inflammatory cytokine expression and activation.

KEY METHODS

CD3/CD28 and lipopolysaccharide activated peripheral blood mononuclear cells (PBMCs) from healthy donors (n = 6) were treated with phytocannabinoid compounds and terpenes in vitro. Flow cytometry was used to determine regulatory T cell (Treg) and T helper 17 (Th17) cell responses to treatments. Cell pellets were harvested for qRT-PCR gene expression analysis of cytokines, cell activation markers, and inflammation-related receptors. Cell culture supernatants were analysed by ELISA to quantify IL-6, TNF-α and IL-10 secretion.

MAIN FINDINGS

In an initial screen of 20 μM cannabinoids and terpenes which were coded to blind investigators, cannabigerol (GL4a), caryophyllene oxide (GL5a) and gamma-terpinene (GL6a) significantly reduced cytotoxicity and gene expression levels of IL6, IL10, TNF, TRPV1, CNR1, HTR1A, FOXP3, RORC and NFKΒ1. Tetrahydrocannabinol (GL7a) suppression of T cell activation was associated with downregulation of RORC and NFKΒ1 gene expression and reduced IL-6 (p < 0.0001) and IL10 (p < 0.01) secretion. Cannabidiol (GL1b) significantly suppressed activation of Tregs (p < 0.05) and Th17 cells (p < 0.05) in a follow-on in vitro dose-response study. IL-6 (p < 0.01) and IL-10 (p < 0.01) secretion was significantly reduced with 50 μM cannabidiol.

SIGNIFICANCE

The study provides the first evidence that cannabidiol and tetrahydrocannabinol suppress extracellular expression of both anti- and pro-inflammatory cytokines in an in vitro PBMC model of inflammation.

T cell activation and lowered T regulatory cell numbers are key processes in severe major depressive disorder: Effects of recurrence of illness and adverse childhood experiences

BACKGROUND

Major depressive disorder (MDD) is characterized by increased T helper (Th)1 polarization, T cell activation (e.g., CD71+ and CD40L+), and cannabinoid receptor type 2 bearing CD20+ B cells; and lower T regulatory (Treg) numbers.

AIMS

To delineate the effects of adverse childhood experiences (ACEs) and recurrence of illness (ROI) on activated T and CB2-bearing B populations, and Tregs, including FoxP3 + CD152+, FoxP3 + GARP+, and FoxP3 + CB1+ cells.

METHODS

We measured ROI, ACEs, the number of activated T cells, Tregs, and CD20 + CB2+ B cells, in 30 MDD patients and 20 healthy controls.

RESULTS

A larger part of the variance in the depression phenome (40.8 %) was explained by increased CD20 + CB2+ and activated T cells, and lowered Tregs. ROI and lifetime suicidal behaviors were significantly and positively associated with CD20 + CB2+, CD3 + CD71+, CD3 + CD40L+, CD4 + CD71+, CD4 + CD40L+, and CD4HLADR+ numbers. ROI was significantly correlated with CD8 + CD40L+ numbers. The sum of ACEs was significantly associated with CD20 + CB2+, CD3 + CD40L+, CD4 + 40 L+ numbers, T cell activation (positively) and Treg (inversely) indices. One replicable latent vector could be extracted from activated T cells, lifetime and current suicidal behaviors, number of depressive episodes, and severity of depression, and 48.8 % of its variance was explained by ACEs.

CONCLUSIONS

ACE-induced activation of T effector and cytotoxic cells and B cells with autoimmune potential, coupled with lowered Treg numbers are a key component of depression. The findings indicate that increasing ROI, the phenome of depression and suicidal behaviors, are caused by autoimmune processes, which are the consequence of ACEs and increasing sensitization of immune responses.

Towards a major methodological shift in depression research by assessing continuous scores of recurrence of illness, lifetime and current suicidal behaviors and phenome features

BACKGROUND

The binary major depressive disorder (MDD) diagnosis is inadequate and should never be used in research.

AIMS

The study's objective is to explicate our novel precision nomothetic strategy for constructing depression models based on adverse childhood experiences (ACEs), lifetime and current phenome, and biomarker (atherogenicity indices) scores.

METHODS

This study assessed recurrence of illness (ROI: namely recurrence of depressive episodes and suicidal behaviors, SBs), lifetime and current SBs and the phenome of depression, neuroticism, dysthymia, anxiety disorders, and lipid biomarkers including apolipoprotein (Apo)A, ApoB, free cholesterol and cholesteryl esters, triglycerides, high density lipoprotein cholesterol in 67 normal controls and 66 MDD patients. We computed atherogenic and reverse cholesterol transport indices.

RESULTS

We were able to extract one factor from a) the lifetime phenome of depression comprising ROI, and traits such as neuroticism, dysthymia and anxiety disorders, and b) the phenome of the acute phase (based on depression, anxiety and quality of life scores). PLS analysis showed that 55.7 % of the variance in the lifetime + current phenome factor was explained by increased atherogenicity, neglect and sexual abuse, while atherogenicity partially mediated the effects of neglect. Cluster analysis generated a cluster of patients with major dysmood disorder, which was externally validated by increased atherogenicity and characterized by increased scores of all clinical features.

CONCLUSIONS

The outcome of depression should not be represented as a binary variable (MDD or not), but rather as multiple dimensional scores based on biomarkers, ROI, subclinical depression traits, and lifetime and current phenome scores including SBs.

Adverse childhood experiences and recent negative events are associated with activated immune and growth factor pathways, the phenome of first episode major depression and suicidal behaviors

This research assessed the effects of adverse childhood experiences (ACEs) and negative life events (NLEs) on forty-eight cytokines/chemokines/growth factors, in 71 FE-MDMD patients and forty heathy controls. ACEs are highly significantly associated with the classical M1 macrophage, T helper (Th)-1, Th-1 polarization, IRS, and neurotoxicity immune profiles, and not with the alternative M2, and Th-2 immune profiles. There are highly significant correlations between ACEs and NLEs and different cytokines/chemokines/growth factors, especially with interleukin (IL)-16, CCL27, stem cell growth factor, and platelet-derived growth factor. Partial Least Squares analysis showed that 62.3 % of the variance in the depression phenome (based on severity of depression, anxiety and suicidal behaviors) was explained by the regression on IL-4 (p = 0.001, inversely), the sum of ACEs + NLEs (p < 0.0001), and a vector extracted from 10 cytokines/chemokines/growth factors (p < 0.0001; both positively associated). The latter partially mediated (p < 0.0001) the effects of ACE + NLEs on the depression phenome. In conclusion, part of the effects of ACEs and NLEs on the depression phenome is mediated via activation of immune and growth factor networks. These pathways have a stronger impact in subjects with lowered activities of the compensatory immune-regulatory system.