ABSTRACT
Title
Thyroid hormones modulate the functional polarization of mouse macrophages
Authors
M. Buldorini1, C. Perrotta1, E. Clementi1, D. Cervia1,2
1Dept of Clinical Sciences, University of Milan
2Dept of Environmetal Sciences, University of Tuscia
1Dept of Clinical Sciences, University of Milan
2Dept of Environmetal Sciences, University of Tuscia
Abstract
Macrophages can be divided on basis of their function: classically activated macrophages (often referred to as M1) are inflammatory and can mediate cytotoxic responses against tumors and intracellular pathogens. Alternatively activated macrophages (typically named M2) are anti-inflammatory and are important for tissue repair responses. It is now generally accepted that M2 have pro-tumoral functions, promoting tumor cell survival, proliferation, and dissemination. There is evidence that different endocrine stimuli influence macrophages differentiation with a mosaic of different and overlapping characteristics. However, the regulation of macrophages exerted by metabolic hormones and the importance of different macrophage subtypes in the development of inflammatory disease are poorly understood. Among endocrine stimuli, thyroid hormones (THs) are produced in the thyroid gland and act on nearly every cell in the body. Cellular actions of THs may be initiated within the cell nucleus, at the plasma membrane, in cytoplasm, and at the mitochondrion. TH receptors (TRs) (nuclear receptors) mediate the biological activities of TH via transcriptional regulation. In this study, we verified the role of TH system on the functional polarization of primary murine macrophages through in vitro and in vivo approaches.
Undifferentiated macrophages (M0) were isolated from femur bone marrow derived cells and polarized to generate M1 and M2 subtypes. We demonstrated that the amplified product corresponding to TRalfa1, TRbeta1 and TRbeta2 mRNAs were clearly detectable. In particular, TRbeta1 was distinctly more expressed in M2 cells vs. M1. Data were also confirmed at protein leve. Cells were then treated with TH during polarization to M1 or M2 and appropriate lineage markers were measured, as for instance f4/80 - a pan-macrophage marker, CD14 - for M1, and CD 206 - for M2. In addition, the expression levels of specific M1 (e.g., TNFalfa, CXCL16, IL1beta, CCL5, CXCL10, CXCL9) or M2 (e.g., IL-13, IL-12, IL-10, CCL2, CXCL12) geneswere also analysed. In another set of experiments, M1 and M2 polarized macrophages were treated with TH before the assessment of genes expression, cytokine release, phagocytosis, and cell invasion. In vivo experiments were conducted in peritoneal macrophages of euthyroid/hypothyroid/hyperthyroid mice. In particular, we analysed the presence of f4/80+CD14+ cells and f4/80+CD206+ cells in mice under normal conditions and during an acute inflammatory state (LPS-treated). Taken toghether, our data suggest that TH has a role in modulating the balance M1/M2 and the functional properties of macrophage populations.
Undifferentiated macrophages (M0) were isolated from femur bone marrow derived cells and polarized to generate M1 and M2 subtypes. We demonstrated that the amplified product corresponding to TRalfa1, TRbeta1 and TRbeta2 mRNAs were clearly detectable. In particular, TRbeta1 was distinctly more expressed in M2 cells vs. M1. Data were also confirmed at protein leve. Cells were then treated with TH during polarization to M1 or M2 and appropriate lineage markers were measured, as for instance f4/80 - a pan-macrophage marker, CD14 - for M1, and CD 206 - for M2. In addition, the expression levels of specific M1 (e.g., TNFalfa, CXCL16, IL1beta, CCL5, CXCL10, CXCL9) or M2 (e.g., IL-13, IL-12, IL-10, CCL2, CXCL12) geneswere also analysed. In another set of experiments, M1 and M2 polarized macrophages were treated with TH before the assessment of genes expression, cytokine release, phagocytosis, and cell invasion. In vivo experiments were conducted in peritoneal macrophages of euthyroid/hypothyroid/hyperthyroid mice. In particular, we analysed the presence of f4/80+CD14+ cells and f4/80+CD206+ cells in mice under normal conditions and during an acute inflammatory state (LPS-treated). Taken toghether, our data suggest that TH has a role in modulating the balance M1/M2 and the functional properties of macrophage populations.