Scientists have identified new pain relief targets that could be used to provide relief from chemotherapy-induced pain. This discovery occurred when scientists were researching how pain occurs in nerves in the periphery of the body.

“We have been investigating and identifying mechanisms underlying pain generation, and our findings could help chemotherapy patients who suffer pain-related side effects,” said Marzia Malcangio, PhD, of King’s College London in the United Kingdom.

One potential side effect of some chemotherapy drugs, such as vincristine, is damage to nerves. This is particularly prominent in hands and feet as the drugs affect nerves in the periphery of the body. This causes pain, which is treated with painkillers. However, some people find that the pain persists.

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Malcangio’s team investigated why the chemotherapy drugs were causing pain in the hopes of resolving the problem. They used mice in the study because mice given the chemotherapy drug also experienced pain in their nerve extremities, such as their hind paws.

By studying the mice, they found that the pain was caused by the mouse’s own immune system responding to damaged blood vessels.

“The chemotherapy drug was found to cause damage to blood vessels around the nerves. When this happened, immune cells leave the blood flow and enter the nerve to help reduce the inflammation, but they also activate pain. Chemicals released naturally by the immune cells were activating the nerves and producing pain,” explained Malcangio.

To try to prevent the pain, researchers looked at ways of stopping the immune cells entering the nerve. They identified receptors on the outside of the immune cells that could be targeted to stop their exit from blood, constituting new types of pain treatment.

“We have discovered that the pain responses are caused by local activation of pain nerves by immune cells and that this could be prevented. Our result can be exploited to produce drugs that, given in combination with treatment, may limit the pain experienced by patients during chemotherapy cycles” added Malcangio. The research was published in the Journal of Clinical Investigation (2014; doi:10.1172/JCI71389).