Fig. 1.

A mechanistic link between opioid signaling and immune modulation via TLR4 and P2X7. Opioid compounds, such as morphine, modulate immune responses not only through classical MOR but also by engaging pattern recognition receptors such as TLR4 and P2X7 on immune cells. Activation of these pathways leads to downstream signaling through NF-κB and MAPK cascades, resulting in the release of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Chronic opioid exposure may therefore contribute to immunosuppression or immune overactivation, depending on receptor context and cellular environment