Summary: Chronic pain differs significantly from acute pain, as it often outlasts the disease that first triggered the pain. The new study shows that persistent pain, like pelvic or lower back pain, in women suffering from recurrent UTIs may be due to overgrowth of nerve endings in the bladder. Thus, many women continue to experience pain and discomfort much after the infection has been eradicated.
Urinary tract infections (UTIs) are not rare, especially among postmenopausal women. They are responsible for about 25% of all the infections in women. However, what is worrisome is that despite the eradication of infection, many women continue to experience persistent or chronic pain.
It means that many women continue to report pelvic pain and a sense of discomfort in the urinary tract, even when the infection has been completely eradicated.
This chronic pelvic and lower back pain can cause much distress in female patients. However, doctors are often unable to explain the cause of such persistent pain. Especially considering that antibiotic therapy can successfully eradicate the infection in most women.
However, a new study suggests that this persistent pain may be due to nerve overgrowth. This makes nerve cells more sensitive, often resulting in poorly understood and chronic pain.
To understand this issue of difficult-to-explain pelvic pain in women, researchers did bladder biopsies of patients known to have experienced recurrent urinary tract infections and complained of persistent pain even after the eradication of the infection. These biopsy samples showed that the nerve cells of these patients were highly activated.
To confirm their findings, researchers also carried out a study in mice. This helped them understand the underlying mechanism causing nerve overgrowth.
When any person experiences a bout of UTI, it results in much damage to the epithelial cells, that is, to the upper protective layer of the bladder. This also results in damage to the nerve cells in the bladder. However, once the infection has been treated, regrowth processes begin, which also includes regrowth of destroyed nerve endings.
However, it appears that due to certain immune responses, which is a natural process, cells like mast cells release nerve growth factors in massive amounts. Thus, in some women, this results in nerve overgrowth, causing increased nerve sensitivity and consequently increasing the risk of persistent pain.
Researchers also focused on countering this issue. Thus, when treating UTI infection in lab mice, they also used certain medications to suppress nerve growth factors. This approach could help reduce the risk of persistent pain in mice by preventing the nerve overgrowth.
So, this research helped us understand the complex nature of persistent pain that occurs in UTI patients. It also highlights how chronic pains differ from acute pain. It means that what works for preventing and managing acute pain would not work for persistent pain or chronic pain syndromes.
Once nerve overgrowth has occurred, it is challenging to reverse. Therefore, this study also shows the importance of early interventions to prevent chronic pains. In many cases, this window of opportunity for preventing chronic pains is missed, and then many patients have to live with persistent or chronic pains for the rest of their lives.
Finally, this study also shows that the pathogenesis of persistent pain may be quite different from acute pain. Therefore, there is a need to find a novel way to prevent chronic pain syndromes. There is a need to develop new kinds of drugs that could help with different types of chronic pains.
Source:
Hayes, B. W., Choi, H. W., Rathore, A. P. S., Bao, C., Shi, J., Huh, Y., Kim, M. W., Mencarelli, A., Bist, P., Ng, L. G., Shi, C., Nho, J. H., Kim, A., Yoon, H., Lim, D., Hannan, J. L., Purves, J. T., Hughes, F. M., Ji, R.-R., & Abraham, S. N. (2024). Recurrent infections drive persistent bladder dysfunction and pain via sensory nerve sprouting and mast cell activity. Science Immunology, 9(93), eadi5578. https://doi.org/10.1126/sciimmunol.adi5578
