“Graft versus host disease (GVHD) pathophysiology is a complex interplay between cells that comprise the adaptive and innate arms of the immune system. Effective prophylactic strategies are therefore contingent upon approaches that address contributions from both immune cell compartments.
In the current study, we examined the role of the type 2 cannabinoid receptor (CB2R) which is expressed on nearly all immune cells and demonstrated that absence of the CB2R on donor CD4+ or CD8+ T cells, or administration of a selective CB2R pharmacological antagonist, exacerbated acute GVHD lethality. This was accompanied primarily by the expansion of proinflammatory CD8+ T cells indicating that constitutive CB2R expression on T cells preferentially regulated CD8+ T cell alloreactivity. Using a novel CB2R-EGFP reporter mouse, we observed significant loss of CB2R expression on T cells, but not macrophages, during acute GVHD, indicative of differential alterations in receptor expression under inflammatory conditions.
Therapeutic targeting of the CB2R with the agonists, tetrahydrocannabinol (THC) and JWH-133, revealed that only THC mitigated lethal T cell-mediated acute GVHD. Conversely, only JWH-133 was effective in a sclerodermatous chronic GVHD model where macrophages contribute to disease biology. In vitro, both THC and JWH-133 induced arrestin recruitment and ERK phosphorylation via CB2R, but THC had no effect on CB2R-mediated inhibition of adenylyl cyclase.
These studies demonstrate that the CB2R plays a critical role in the regulation of GVHD and suggest that effective therapeutic targeting is dependent upon agonist signaling characteristics and receptor selectivity in conjunction with the composition of pathogenic immune effector cells.”
“Cannabinoids have long been used for their psychotropic and possible medical properties of symptom relief. In the past few years, a vast literature shows that cannabinoids are neuroprotective under different pathological situations.
“∆ 9 -Tetrahydrocannabinol (∆9 -THC), the active phytocannabinoid in cannabis, is virtually an adjunct to the endogenous endocannabinoid signaling system.
“While activation of cannabinoid (CB2) receptors has been shown to be neuroprotective, no studies have examined whether this neuroprotection is directed at cerebral arterioles and no studies have examined whether activation of CB2 receptors can rescue cerebrovascular dysfunction during a chronic disease state such as type 1 diabetes (T1D).
“Cannabis exposure is becoming more common in older age but little is known about how it is associated with brain health in this population.
“To determine if cannabis may be used as an alternative or adjunct treatment for intermittent and chronic prescription opioid users.
“The prevalence of mild traumatic brain injury is highest amongst the adolescent population and can lead to complications including neuroinflammation and excitotoxicity.
“Δ9 -Tetrahydrocannabinol (THC), the main bioactive compound found in the plant Cannabis sativa, exerts its effects by activating cannabinoid receptors present in many neural cells.