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Macrophages are phagocytic cells located in tissues, organs and even circulated within our body as white blood cells. Based on the local cytokine milieu in tissue sites, macrophages may be polarized into pro-inflammatory M1 or anti-inflammatory M2 phenotypes. Receptor tyrosine kinase Mer (MERTK) helps in clearing dead neutrophils and other apoptotic cells from damaged tissue sites preventing chronic inflammation and autoimmune disorders. MERTK aids in the maintenance of tissue homeostasis and wound healing. Phosphatidylserine (PtdSer) present on the surface of apoptotic cells release “eat me” signals which are recognized by the two “bridging ligands” of MERTK receptor, Gas6 and ProS. The binding of the ligands to PtdSer initiates intracellular signals leading to phagocytosis of the cell. MERTK receptor is expressed mostly on M2c macrophages.

The current study explores the expression rate of the phagocytic receptor MERTK, on macrophages polarized with either IL-10 (M2c ells) or IL-4 or IL-13 (M2a macrophages) following treatment with the suppressor of cytokine signaling SOCS3 in comparison with macrophage polarization with only IL-10 or IL-4 or IL-13 . It exhibits an enhancement in the expression of the phagocytic MERTK receptor on the surface of IL-10 polarized M2c macrophage when treated with SOCS3 in comparison to IL-10 polarized M2c macrophage, IL-4 polarized M2a macrophage and IL-13 treated M2a macrophage. IL-13 polarized M2a macrophage also shows an increase in the expression of MERTK receptor which is similar to a previous study where a similar receptor to MERTK termed “Axl receptor” is enhanced by IL-13 treatment on bone- marrow derived macrophage. SOCS3 treated with IL-13 polarized M2a macrophage acts as a negative regulator of MERTK receptor by decreasing the expression contrasting to the effect of SOCS3 on IL-10 which enhances the expression.

Future research will involve co-culturing SOCS3 polarized M2 macrophages with apoptotic cells such as N2a neuroblastoma cells.

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Immunology and Infectious Disease | Microbiology

Colleges & Schools

Science and Mathematics


Microbiology & Immunology Program

Faculty Advisor Name

Dr. Nancy Bigley

Enhanced expression of receptor tyrosine kinase Mer (MERTK) on SOCS3-treated polarized RAW 264.7 anti-inflammatory M2c macrophages