Acute pain, or ‘nociceptive’ pain, has an advantage—it tells us to stop whatever it was we were doing and prevents further tissue damage. ‘Neuropathic pain’ on the other hand, continues long after initial injury and has no apparent benefit. HIV-related neuropathic pain is an all too common side effect of a long term infection: patients suffer from numbness, chronic pain and may even feel pain with a gentle touch. “One in two AIDS patients suffers from chronic pain,” explains Dr. Peter Smith, a neuroscientist at the University of Alberta. “This type of pain fails to respond to currently available drugs like morphine.” But where is this pain coming from and how can it be treated? Dr. Smith and his colleagues are working to find out.
Dr. Smith’s interest in science started early; “I was a science nerd when I was a kid” he admits, “I liked chemistry and electronics.” This interest led him to an undergraduate degree in physiology and biochemistry, where he became intrigued with electrophysiology—the study of the electrical activity of brain and nerves. “The cool thing about electrophysiology is that you actually see stuff happening: nerves responding to stimulation or medication.” It was his interest in medications that led him to his current research: “I was fascinated how a few milligrams of a drug can have such a profound effect on a person’s behaviour or health. All of this led me to an interest in neuropharmacology and neurophysiology.”
“Initially it was pretty esoteric stuff,” says Dr. Smith, speaking about the early days of his research. “But eventually we realized our work was very relevant to understanding neuropathic pain and this has become the main thrust of my research. I never thought I’d be working on HIV/AIDS but I am very pleased to be in a field that has relevance to an important clinical problem and I enjoy exchanging notes with clinicians and other health care professionals.”
Dr. Smith’s research focuses on HIV-related neuropathic pain. “We know that HIV promotes the production of a toxic protein called ‘Vpr’ which damages sensory nerves whilst causing them to generate pain impulses,” he explains. “These impulses constantly enter the spinal cord and brain.”
Vpr is a protein that the HIV virus requires to replicate, but it has negative effects on the human body. It affects the electrical properties of ion channels—the pores in nerve cells that control their electrical activity—and generates nerve impulses causing chronic pain. Dr. Smith in collaboration with a neurologist, Dr Christopher Power, is researching the mechanisms behind this, and thus how it can be controlled. “We use electrical recordings of sensory nerve activity in the presence or absence of Vpr to determine which ion channels it affects.” Using mice models that produce Vpr, Dr. Smith can study the alleviation of pain using medications that reduce the effects of Vpr on neuron activity. “If these medications reduce pain, it will lead to the development of urgently needed treatments for pain in AIDS patients,” says Dr. Smith. “We hope our findings can provide a direct route to clinical trials.”
CIHR is supporting Dr. Smith’s work through a three year research grant. “CIHR support has been absolutely essential in providing salaries for technologists, research associates and students,” says Dr. Smith. “They have helped to cover essential costs such as animal purchase and maintenance, laboratory expendables and minor equipment.”
The Canadian Association for HIV Research (CAHR), the CIHR HIV/AIDS Research Initiative, the Canadian Foundation for AIDS Research (CANFAR), the CIHR Canadian HIV Trials Network (CTN) and the Canadian HIV Vaccine Initiative (CHVI) Research and Development Alliance Coordinating Office (ACO), would like to congratulate Dr. Smith for his significant contributions to our understanding of HIV. His work is part of a larger Canadian research effort that is making a difference in the lives of those affected by HIV in Canada and around the world.