Background
As advancements in cancer treatments emerged, they brought along unavoidable side effects. Radiation therapy, now a cornerstone in oncology, comes with persistent impacts on the body, one of the most significant being radiation-induced skin injury (RISI) (Jaschke et al., 2017). This condition remains a common and challenging complication for both patients and clinicians.
The skin serves as a physical shield and a habitat for a diverse ecosystem of microorganisms, collectively known as the microbiota. These microbes play a critical role in maintaining skin health by supporting wound healing, regulating inflammation, and preventing infections. Any disruption to this microbial balance can have extensive consequences for recovery and immune response.
Emerging research highlights the intriguing connection between ionizing radiation and shifts in the skin’s microbial ecosystems. According to Huang et al., ionizing radiation can alter the composition and function of the skin microbiome, potentially influencing how well the skin heals, responds to inflammation, and combats infection. Although the full implications of these microbial changes are not yet fully understood, studies suggest that harnessing the microbiome may unlock new therapeutic methods. Investigating how these microorganisms respond to radiation damage could pave the way for treatments that enhance and minimize long-term complications.
Central Question
How does radiation-induced skin injury disrupt the skin microbiome and how does it influence the healing of skin injuries?
Evidence
The harmful consequences of radiation exposure are well-documented through both clinical experiences and historical events. Large-scale nuclear disasters like Chornobyl offer concrete evidence of radiation’s impact, not only on immediate health but also on long-term survivorship. Following the Chornobyl disaster, many survivors developed severe health complications, including skin wounds caused by radiation exposure (Steinert et al., 2003). In extreme cases, these wounds became a leading cause of mortality, as the skin’s ability to heal was compromised by both radiation and environmental contamination.
Even with strict codes for nuclear power plants continue to malfunction and cause disasters. One of the most notable in the United States was the incident at Three Mile Island in Pennsylvania (US NCR, 2024). While no health problems arose from this meltdown such cases highlight the importance of understanding how radiation damages the skin and how microbial ecosystems on the skin’s surface may respond to injury.
Even with the known risks of radiation, it is still used in the medical field. While radiotherapy has proven highly effective in targeting tumors, the treatment often comes with unintended damage to surrounding healthy tissue, especially the skin (Jaschke, W. et al., 2017). This damage can result in painful injuries, some of which persist long after the cancer treatment concludes. Acute radiation-induced skin injury (RISI) manifests within hours to weeks after exposure, with symptoms such as redness, dryness, and peeling (Yang, X. et al., 2020). More severe cases can progress to skin blisters and open wounds. On the other hand, chronic RISI appears months to years later, often characterized by scarring, persistent ulcers, or fibrosis; leading to long-term discomfort and reduced skin elasticity, impairing quality of life and complicating future treatments.
To explore these mechanisms, researchers developed a mice model for the study (Huang et al., 2022). This gave them a way to analyze new data with previous human data taken from major events. They looked at a very specific segment of ribosomal RNA (rRNA) that all bacteria have which allowed them to analyze changes in the skin’s microbial communities. This method allowed them to detect not only common microbes but also rare bacteria that might play a role in the healing process. They compared the results from irradiated samples with control groups to understand how radiation alters the skin’s microbiome (Huang et al., 2022).
Surprisingly, their findings revealed that while the overall microbial diversity did not decrease significantly, a specific bacterial group, Firmicutes (or Bacillota), was consistently elevated during the most rapid phases of wound healing. Firmicutes, a family of gram-positive bacteria, include species known for their resilience in harsh environments. Many Firmicutes are also recognized as probiotics, capable of withstanding dehydration and environmental stress—qualities essential for maintaining skin health after radiation exposure. The researchers speculate that the rise in Firmicutes may be part of the body’s stress response to the damaged skin barrier. This response aims to create a form of biological “armor,” helping to restore the compromised barrier and protect the tissue from further radiation-related harm.
Figure 2: Relative abundance on the family level in RISI vs Control Patients. (Huang et al., 2022)
While the abundance of firmicutes increased, multiple types of bacteria decreased. Specific types of bacteria (proteobacteria, bacteroidetes, and actinobacteria) decreased greatly in RISI patients. This proves the harshness of the treatments on the skin microbiome. The abundance levels highlight the significant impact of radiation-induced skin injury (RISI) treatments on the skin microbiome. These shifts emphasize the treatments’ harsh effects on microbial diversity, with drastic changes observed post-treatment.
These findings suggest that understanding how microbiota like Firmicutes respond to radiation-induced injuries could unlock new therapeutic strategies. Treatments that support or mimic the actions of beneficial bacteria may enhance the healing process and mitigate the chronic effects of RISI. Further studies are needed to explore these possibilities, but the role of the skin microbiome presents a promising frontier in improving recovery from radiation injuries and managing the long-term effects of radiotherapy.
My Questions
Overall, this study provides an insightful foundation, but further exploration in human studies with volunteer cancer patients would add substantial value. Understanding the dynamics of the microbiome in human skin, especially under real-world clinical conditions, could reveal more about the interactions between skin microbiota and radiation injuries.
One of the central questions arising from this research is whether we can intentionally manipulate the skin microbiota to promote improved recovery outcomes. If such manipulation is feasible, then specific bacterial populations like Firmicutes could be harnessed not only as a treatment for radiation-induced injuries but also for broader applications in managing other skin disorders where microbiome balance plays a crucial role (Smythe, 2023).
To test these possibilities, future studies could investigate the effects of probiotics or targeted microbiome transplants on irradiated skin. Additional research could explore the resilience of beneficial bacteria and their capacity to adapt within damaged skin environments. The biggest question is if there is a way to reverse damaged skin by using microbes. By confirming whether a microbiome-focused therapy could effectively restore or even enhance the skin’s natural healing processes, we may open up innovative therapeutic strategies for skin conditions beyond RISI.
Further Reading
The Skin Microbiome: Current Landscape and Future Opportunities
For a deeper dive into the role of skin microbiota in health and disease, Smythe and Wilkinson’s (2023) review offers a comprehensive look at the current state of research and future possibilities in this field. Published in the International Journal of Molecular Sciences, this paper explores how the skin’s microbial communities influence wound healing, inflammation, and immune responses, which are all critical factors in radiation-induced skin injury (RISI). If you’re interested in understanding how advances in microbiome science could unlock new therapeutic strategies for conditions like RISI, this article provides valuable insights.
Human Skin Microbiome: Impact of Intrinsic and Extrinsic Factors on Skin Microbiota
The study by Skowron et al. (2021) offers valuable insights into how both intrinsic (e.g., genetics, age) and extrinsic (e.g., environmental exposure) factors shape the skin microbiome. This research is particularly relevant to understanding radiation-induced skin injury (RISI) because radiation acts as a significant extrinsic factor that disrupts the microbial balance. Such disruptions can impair wound healing and immune defenses, as noted by other studies like Huang et al. By exploring the mechanisms outlined in Skowron’s work, researchers can better grasp how environmental stressors, such as ionizing radiation, alter the microbiome, potentially paving the way for innovations.
References
Huang, B., An, L., Su, W., Yan, T., Zhang, H., & Yu, D. (2022). Exploring the alterations and function of skin microbiome mediated by ionizing radiation injury. Frontiers in Cellular and Infection Microbiology, 12. https://doi.org/10.3389/fcimb.2022.1029592
Jaschke, W., Schmuth, M., Trianni, A., & Bartal, G. (2017). Radiation-induced skin injuries to patients: what the interventional radiologist needs to know. Cardiovascular and Interventional Radiology, 40(8), 1131-1140. https://doi.org/10.1007/s00270-017-1674-5
Smythe, P., & Wilkinson, H. N. (2023). The skin microbiome: Current landscape and future opportunities. International Journal of Molecular Sciences, 24(4), 3950. https://doi.org/10.3390/ijms24043950
Steinert, M., Weiss, M., Gottlöber, P., Belyi, D., Gergel, O., Bebeshko, V., Nadejina, N., Galstian, I., Wagemaker, G., Fliedner, T. M., & Peter, R. U. (2003). Delayed effects of accidental cutaneous radiation exposure: fifteen years of follow-up after the Chornobyl accident. Journal of the American Academy of Dermatology, 49(3), 417–423. https://doi.org/10.1067/s0190-9622(03)02088-7
United States Nuclear Regulatory Commission. (2024, March 28). Backgrounder on the Three Mile Island accident. NRC Web. https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html
Yang, X., Ren, H., Guo, X., Hu, C., & Fu, J. (2020). Radiation-induced skin injury: Pathogenesis, treatment, and Management. Aging, Volume 12, Issue 22. https://doi.org/10.18632/aging.103932
Yungang Hu, Lu Yu, Weili Du, Xiaohua Hu and Yuming Shen. (2024). Global hotspots and research trends of radiation-induced skin injury: a bibliometric analysis from 2004 to 2023. Front. Oncol. 14:1430802. https://doi.org/10.3389/fonc.2024.1430802