New research on the immune system’s role in addiction may help scientists develop a drug to treat and prevent opioid addiction, including addiction to prescription painkillers. Focusing on the immune system’s response to opioids such as morphine, researchers from the University of Adelaide in Australia and the University of Colorado found that opioids bind to immune receptor Toll-Like receptor 4 (TLR4), which is a bacteria receptor. This receptor also recognizes morphine and causes immune cells in the brain to “hijack the reward pathways,” increasing the levels of dopamine in the brain that can lead to physical addiction. Lead researcher Dr Mark Hutchinson told Fox News that if drugs to block TLR4 can be developed, the reward response can be blocked, preventing physical opioid addiction. Thus far, studies on the drug naloxone have shown positive results in blocking the TLR4 response. The researchers also found that blocking the TLR4 response increased the pain relief from morphine. Hutchinson indicated that there may be potential for developing a drug containing a TLR4 blocker and morphine in order to treat pain and prevent addiction.