Date of Award

Spring 2019

Document Type

Honors Thesis


Basic Biomedical Science

First Advisor

Dr. Yifan Li

Second Advisor

Dr. Kathleen Eyster

Third Advisor

Dr. Hong Zheng


Interleukin-6 (IL-6) was originally found as a cytokine in leukocytes that is involved in inflammation responses. With recent discovery of skeletal muscle endocrine function, several classical cytokines were found to be secreted from skeletal muscle, termed myokines. IL-6 has shown to be released from skeletal muscle as a myokine. As heterogenous tissue, skeletal muscle consists of at least four different types of muscle fibers characterized by distinct metabolic and functional properties. While IL-6 is known to regulate muscle metabolism and function, whether IL-6 release from skeletal muscle is muscle type specific is unclear. This study was designed (1) to validate an ex vivo method to test IL-6 release from isolated mouse skeletal muscle; and (2) to compare IL-6 release from slow and fast twitch muscle. Male and female C57/B6 mice at the ages of 3-4 months were anesthetized with isoflurane, extensor digitorum longus (EDL) (fasttwitch muscle) and soleus (slow-twitch muscle) were isolated and incubated in Krebs solution at 37 ºC with bubbling oxygen. Secreted IL-6 in the media was detected by the ELISA and western blot analyses. The results showed that IL-6 release was induced from isolated muscle in a temperature and O2 dependent manner. IL-6 muscle release was cell-type specific with little secretion shown from the EDL but a strong release from soleus. Consistently, IL-6 protein secretion was greater in soleus tissue than that in EDL tissue. Moreover, while EDL expresses and releases little IL-6, it shows strong release of MMP-9 and other unidentified proteins. Overall, the results of this study suggest that skeletal muscle release of IL-6 is muscle fiber type specific.



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