A new study by Michigan State University (MSU) researchers suggests that blocking inflammation after surgery may delay recovery and prolong pain, challenging standard medical protocols. The research, published in the Journal of Pain Research, found that allowing inflammation to proceed naturally led to a quicker resolution of pain and overall recovery following surgery or injury. This outcome was unexpected.
The study utilized a mouse model to examine postoperative pain, comparing scenarios with and without activity from the immune signaling molecule TNF-α (tumor necrosis factor alpha). Researchers inhibited TNF-α, which promotes inflammation, and performed a simulated surgery via a small incision. Contrary to expectations, blocking TNF-α resulted in mice experiencing pain for a significantly longer duration. According to Geoffroy Laumet, the study's senior author and an associate professor at MSU, this inhibition prevented the body from naturally deactivating pain.
Laumet initially questioned the results, but the findings were consistent after repeated experiments by multiple lab members using three different TNF-α inhibition methods, including Etanercept, an FDA-approved drug used in humans. While pain typically resolves for 90% of patients after surgery, approximately 10% develop chronic pain that is resistant to medication and can persist for years. With over 40 million Americans undergoing surgery annually, an estimated 4 million develop chronic postsurgical pain each year.
Laumet's research indicates that the body's ability to produce TNF-α in response to surgical injury could be a critical factor in pain resolution. The study does not recommend discontinuing anti-inflammatory drugs entirely, as many molecules are involved in inflammation, pain, and healing. The goal is to identify specific molecules that contribute to pain versus those that contribute to pain resolution, allowing for targeted treatments. While blocking TNF-α after surgery may be inadvisable based on these findings, it may still be beneficial in other contexts, such as reducing arthritic inflammation in autoimmune diseases like rheumatoid arthritis.
Laumet emphasized that inflammation is not inherently detrimental. While it causes pain, it also works internally to facilitate pain resolution. He suggested that the medical practice of immediately blocking inflammation after an injury may not always be the optimal strategy and expressed optimism that future research could enable pain blocking while allowing beneficial inflammation for healing.