CBD's complex immune effects offer hope for transplant pain relief

BACKGROUNDCannabidiol (CBD) is increasingly used for pain management, including in transplant recipients with limited analgesic options. Its immunomodulatory effects in humans are not well defined at a single-cell level at CBD steady state with concomitant tacrolimus treatment.METHODSIn a phase I ex vivo study, peripheral blood mononuclear cells from 23 participants who received oral CBD (Epidiolex) up to 5 mg/kg twice daily for 11 days were collected before CBD (pre-CBD) and at steady state (post-CBD). Lymphocytes were isolated and stimulated with anti-CD3/CD28 antibodies, with or without tacrolimus (5 ng/mL). Pharmacodynamic responses were assessed using CellTiter-Glo proliferation, single-cell and single-nucleus RNA sequencing, cytokine assays, and flow cytometry. Steady-state plasma concentrations of CBD were quantified via tandem mass spectrometry.RESULTSWe identified an increased proportion of T effector memory (TEM) cells post-CBD (22% increase), which correlated with CBD plasma concentrations (R = 0.77, P = 0.01). CBD reduced proliferation of T (37% decrease) and CD70hi B (17% decrease) lymphocytes with additive immunosuppressive effects to tacrolimus. Single-cell RNA sequencing revealed reduced IL2 and TNF signaling and altered receptor-ligand networks in TEM cells. Post-CBD cytokine assays revealed elevated proinflammatory IL-6 protein levels and antiinflammatory IL-10 levels, with reduced TNF-α, LTA, and IL-2. In flow cytometry, the proportion of TEM and TEMRA cells increased post-CBD with tacrolimus.CONCLUSIONCBD exerts mixed immunomodulatory effects in humans, combining antiproliferative and pro- and antiinflammatory responses. Understanding the clinical safety of CBD use is important given the paucity of pain control options available for immunocompromised transplant populations.TRIAL REGISTRATIONClinicalTrials.gov NCT05490511FUNDINGNIH/National Center for Complementary and Integrative Health (R01AT011463); NIH/National Institute of General Medical Sciences (NIGMS) (R35GM145383); Intramural Research Program of the NIH; NIH/NIGMS (T32GM008425).