Chronic pain and nerve injuries reshape immune system differently in men and women, says study

Chronic pain: Prolonged immune disruptions could not only prolong chronic pain but also contribute to anxiety, depression, and other related condition (Image: Pexels)

A spasm, a sting, a sudden jolt of pain... nerve injuries can cause various discomforts. Scientists at McGill University say that such injuries don’t just remain localised; they send shockwaves through the entire immune system. Surprisingly, the body’s response varies depending on whether you’re male or female, hinting at entirely different biological pathways for pain.

Nerve injuriesare notoriously tricky. They can arise from a stretch, a cut, or even sustained pressure, often leaving behind chronic pain that refuses to ease. While the immune system typically rushes to repair damaged tissue, researchers have discovered that nerve injuries can fundamentally reshape immune activity across the body, not just at the injury site.

In a series of preclinical experiments, McGill scientists observed male and female mice following nerve injuries. The results were startling. Male mice displayed heightened inflammatory markers in their blood, signalling a strong immune reaction. Female mice, on the other hand, showed almost no such inflammation.

Yet in a curious twist, blood from injured males or females, when transferred to healthy mice, triggered increased sensitivity to pain in both sexes. This suggests that females may be transmitting pain via a completely different, previously unknown pathway.

Distinct immune  patterns between genders

Here are some distinct immune patterns in males and females, according to the study.

Male mice: Strong, persistent inflammatory signals circulate in the bloodstream.

Female mice: Inflammatory markers remain largely unchanged.

Pain transmission: Despite the differences, blood from either sex can induce pain in healthy mice, implying hidden mechanisms at work.

Other health implications:

Nerve injuries may have far-reaching consequences beyond the initial damage. Prolonged immune disruptions could not only prolong chronic pain but also contribute to anxiety, depression, and other related conditions. As Dr Ji Zhang, a senior author of the study, notes, “A localised nerve injury can affect the whole body, and men and women may respond differently.”

Understanding these sex-specific immune responses is more than academic. “By appreciating how men and women react differently to nerve injuries, we can develop targeted treatments for chronic pain,” explains Sam Zhou, lead author and PhD student at McGill. The findings highlight exciting avenues for personalised medicine, offering hope for therapies that actually address the root of chronic pain rather than just masking it.

Nerve injuries are not just about the point of impact, they can ripple through the immune system in ways we’re only beginning to understand. McGill’s study exposes hidden sex-specific pathways of pain, offering a glimpse into a future where chronic pain treatments are as personalised as they are effective.