Plasma Growth Arrest Specific-6 and Axl Levels in Patients with Hyperthyroidism / Hypothyroidism

Objective: Growth Arrest Specific-6 is the ligand of the Tyro, Axl, and Mer (TAM) receptors subfamily of the receptor tyrosine kinase family. Gas6/Axl signaling pathway is highly regulated in several pathological conditions. The role of Gas6/Axl signaling in hypothyroidism and hyperthyroidism has not been explored previously. In this study, we aim to investigate possible changes in plasma Gas6 and Axl levels in patients with hyperthyroidism and hypothyroidism. Methods: In the study, 33 patients who were diagnosed with hypothyroidism, 35 patients who were diagnosed with hyperthyroidism and 36 healthy volunteers were included as the control group. Gas6, Axl, IL-6, TNF-α, and AOPP levels in plasma were measured with ELISA kits, MDA and TAC levels were measured with colorimetric kits. Results: The plasma Axl level of the hyperthyroid patient group was significantly higher than control group (p<0.05). MDA levels were significantly higher in both hyperthyroid and hypothyroid patient groups compared to the controls (p<0.01, p<0.01, respectively). Plasma TAC level were found to be significantly lower, while AOPP were higher than controls in hyperthyroid group (p<0.05, p<0.05 respectively). In all groups, Gas6 and Axl have positive correlations, both among themselves and with IL-6 and TNF-α levels. Conclusion: Our results support the hypothesis that the Gas6/Axl signaling pathway may be involved in the pathogenesis of these diseases. In addition, it can be thought that lipid peroxidation increases and antioxidant defense is impaired in both hyperthyroidism and hypothyroidism.