Exploratory Study on the Role of Gas6 in Vascular Inflammation
Open Access
- Author:
- Sandiford, Jalyn
- Area of Honors:
- Biology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Stephen Wade Schaeffer, Thesis Supervisor
Stephen Wade Schaeffer, Thesis Honors Advisor
Yingwei Mao, Faculty Reader - Keywords:
- Gas6
Sickle Cell Disease
Myeloproliferative Neoplasms
Enzyme-Linked Immunoassay
Western Blot - Abstract:
- Growth arrest - specific 6 (Gas6) protein is a member of a vitamin K-dependent protein family with growth factor-like properties through its interactions with Tyro3, Axl, and Mer tyrosine kinases (TAM family). Gas6 can affect primary hemostasis and can affect coagulation it also displays anti- or pro-inflammatory effects depending on co-receptors and cell type. Furthermore, Gas6 is involved in platelet activation and the recruitment of inflammatory cells. Two diseases were studied that are both accompanied by inflammation: Sickle Cell Disease (SCD) and Myeloproliferative Neoplasms (MPN) – focusing on Polycythemia Vera (PV). In PV, due to JAK2V617F mutation leading to constitutive JAK-STAT signaling, patients present with elevated hematocrit and exhibit increased markers of vascular inflammation and thrombosis. In SCD, due to single point mutation in hemoglobin, results in deformed red blood cells which adhere to the vasculature and hemolysis, resulting to severe pain and inflammation. As Gas6 may play a role in vascular inflammation, we hypothesize that Gas6 protein will be elevated in the plasma JAK2V617F+ PV patients and SCD patients. To test this hypothesis, in experiment 1, we collected citrate or EDTA plasma samples from adult JAK2V617F and SCD patients. Next, using an enzyme-linked immunoassay (ELISA), we quantified Gas6. In MPN samples, compared to elevated hematocrit controls (n=8, median 17.7 ng/mL), JAK2V617F PV subjects had a significant increase (median 32 ng/mL, p<0.001, t-test). In SCD patients, there was not a significant difference between the Gas6 levels in the SCD patients and the controls. In a further experiment, we performed a Western blot on the JAK2V617F PV subjects and found in the transfection model, increased expression of JAK2V617F in endothelial cells leads to increased Gas6 protein. The JAK2V617F PV subjects data supports my hypothesis, suggesting that the role of Gas6 in vascular inflammation is higher in MPN-PV patients. Further studies evaluating the role of platelet interactions as well as interactions between TAM family kinases in these diseases is warranted. In SCD, with no significant difference in gas6 levels versus elevated hematocrit control subjects, the data does not support my hypothesis. More analysis is needed and further evaluation stratifying patients by the following variables may help sickle cell genotypes (SS, SC, S-beta thal) or by treatment (hydroxyurea, crizanulizumab).