Beyond single-drug treatment for chronic pain: dissecting the molecular effects of pregabalin and ∆9-THC on opioid signaling modulation to implement innovative pharmacotherapy via a Quantitative Systems Pharmacology-based platform

Chronic pain is a multifaceted illness involving biological, psychological, and social factors severely lowering patients’ quality of life. Single-drug therapies seldom provide adequate relief and come with undesirable side effects. Multimodal analgesia—combining different drugs to target multiple pain-relieving mechanisms—has shown promise in reducing pain and minimizing opioid use. However, due to the incomplete understanding of pain mechanisms and the variability among individuals, the selection of effective drug combinations has largely been based on trial and error. Emerging technologies, such as Quantitative Systems Pharmacology (QSP), integrate in silico pharmacology, pharmacogenetics, and systems biology to characterize dynamic interplays between drugs and the physiopathology at multiple biological levels. To implement a QSP-based platform for predicting innovative combinations of existing opioid/non-opioid drugs eliciting analgesic synergy and reduced adverse effects, this research aims to investigate the effects of pregabalin and ∆9-tetrahydrocannabinol (THC) co-administration on the signaling pathways associated to opioid receptors in brain region-specific rat and mouse primary neuronal cultures and in human cell models. Findings indicated that morphine, pregabalin, and their combination modulated the expression of pain/analgesia-related targets in a system- and brain region-specific manner. Low concentrations of pregabalin and THC affected morphine signaling at the µ opioid receptor (MOR), improving adenylyl cyclase inhibition and rescuing morphine’s activity following MORs desensitization. Additionally, the study confirmed that MOR and cannabinoid receptor 1 (CB1) colocalized. Mutating key residues at receptor interfaces altered signaling, further supporting the role of MOR-CB1 dimers in morphine-THC cross-talk. These results sustained combination therapy using gabapentinoids or cannabinoids with opioids, as low-dose co-administration could enhance analgesia while reducing side effects. The in vitro data collected, integrated with preclinical and clinical findings obtained by other QSPainRelief consortium partners, will populate the QSP database, contributing to developing a model platform for predicting more efficacious and secure medicine combinations to treat chronic pain.