Ultrasound Monitoring of Thymus Involution in Septic Mice

Thymus involution is characterized by a progressive regression of thymus size and contributes to immunosuppression in sepsis. High-frequency ultrasonography is a non-invasive monitoring system in multiple organs, including the thymus, in mice. However, thymus involution has not been studied using ultrasonography in septic mice. This study reports ultrasound approaches to monitoring septic thymus involution in mice. Sepsis was induced by cecum ligation and puncture (CLP). Mice were euthanized at three time points: baseline and days 3 and 10 after CLP. Thymus areas and volumes were measured using 2-D and 3-D ultrasound approaches. Thymus weights were measured ex vivo. Compared with values at baseline, both thymus area and volume decreased significantly at days 3 and 10. In addition, thymus areas and volumes correlated positively with thymus weights. In conclusion, ultrasonography provides reliable thymus measurements and is an optimal technique for monitoring thymus involution in septic mice.