The current opioid epidemic warrants a better understanding of genetic and environmental factors that contribute to opioid addiction. Here we report an increased prevalence of vitamin D (VitD) deficiency in patients diagnosed with opioid use disorder and an inverse and dose-dependent association of VitD levels with self-reported opioid use. We used multiple pharmacologic approaches and genetic mouse models and found that deficiencies in VitD signaling amplify exogenous opioid responses that are normalized upon restoration of VitD signaling. Similarly, physiologic endogenous opioid analgesia and reward responses triggered by ultraviolet (UV) radiation are repressed by VitD signaling, suggesting that a feedback loop exists whereby VitD deficiency produces increased UV/endorphin-seeking behavior until VitD levels are restored by cutaneous VitD synthesis. This feedback may carry the evolutionary advantage of maximizing VitD synthesis. However, unlike UV exposure, exogenous opioid use is no
P2RY8 is a G protein–coupled receptor (GPCR) that is involved in restraining germinal center (GC) B cell migration and growth. It is unclear how the ligand of P2RY8, S -geranylgeranyl-l-glutathione (GGG), is involved in these processes. Using gain-of-function mouse models and genetically modified human T cells, Gallman et al. showed that expression of gamma-glutamyltransferase-5 (Ggt5) on stromal cells and ATP-binding cassette subfamily C member 1 (Abcc1) on hematopoietic cells was involved in catabolizing and transporting GGG, respectively, and restraining P2RY8+ cells within GCs. GGG and P2RY8 interactions also restrained lymphocyte trafficking to the bone marrow. Thus, GGG and P2RY8 processing and interactions are crucial for the confinement of B cells within GCs and for inhibiting migration of lymphocytes into bone marrow.
P2RY8 promotes the confinement and growth regulation of germinal center (GC) B cells, and loss of human P2RY8 is associated with B cell lymphomagenesis. The m