New Research on Exosomes May Lead to Better Shingles Pain Treatments

<>

Understanding Shingles and Post-Herpetic Neuralgia

The varicella zoster virus, which causes chickenpox, infects over 90% of the world’s population, typically during early childhood in temperate regions or adolescence and early adulthood in tropical regions. Following the initial infection, the virus remains dormant within pain-sensing neurons. Even individuals vaccinated with the live, weakened strain introduced in the United States in 1995 still harbor the dormant virus in their neurons.

In approximately one-third of the global population, the virus reactivates decades later to trigger a painful shingles rash, with rates increasing worldwide for reasons not yet fully understood. While symptoms usually resolve within a couple of weeks, about 10% to 18% of patients develop post-herpetic neuralgia if pain persists longer than three months after the rash clears. The risk of developing this chronic condition rises significantly with age, and the resulting pain can last for years or even a lifetime, severely diminishing quality of life and sometimes bringing emotional distress and suicidal thoughts.

The Role of Exosomes in Nerve Damage

Clinicians and researchers have long sought to understand why post-herpetic neuralgia occurs, especially since skin biopsies of affected areas reveal a puzzling reduction in sensory nerve fibers despite normal-looking skin. This counterintuitive loss of nerve fibers frequently results in heightened pain. Although ongoing or intermittent viral replication within sensory neurons was traditionally suspected of causing this persistent damage, antiviral treatments that stop viral replication do not reliably prevent or reduce the condition.

To explore noninfectious contributors, Andrew Bubak and his research team at the University of Colorado Anschutz investigated exosomes, which are microscopic particles released by every cell type in the body. These particles carry bioactive cargo, including proteins and nucleic acids, designed to alter recipient cell behavior and facilitate intercellular communication. Because the team’s prior laboratory work revealed that exosomes from patients with active shingles increase stroke risk and inflammation, researchers examined how these circulating particles impact neurons directly.

Current Treatment Landscape and Limitations

Current management options for post-herpetic neuralgia largely focus on relieving symptoms rather than addressing underlying mechanisms, leaving less than 50% of patients with meaningful pain relief. Prescription antiviral drugs such as acyclovir, valacyclovir, and famciclovir can reduce the length and severity of an outbreak and help prevent post-herpetic neuralgia if administered early enough. Additional therapies range from over-the-counter pain medications and nonsteroidal anti-inflammatory drugs to narcotic pain medications, depending on severity.

Patients also utilize nonmedical remedies, including cool compresses, anti-itching lotions like calamine lotion, and aluminum acetate solutions to dry up blisters. For managing established post-herpetic neuralgia pain, clinicians prescribe tricyclic antidepressants, antiseizure medications, topical capsaicin cream, and lidocaine patches. By uncovering how exosomes alter neurons, this new research from the University of Colorado Anschutz points toward future pathways that could yield more targeted treatments beyond current symptom relief.