engleski

Pro-inflammatory effects of galectin-3 on monocytic-macrophage cells

Galectin-3 (gal-3), a β-galactoside binding lectin has been recently recognized a potent and very useful diagnostic and prognostic marker for heart failure. In addition, it exerts important roles in many other (patho)physiological processes (adhesion, proliferation, differentiation, apoptosis, inflammation, neoplastic transformation, spreading metastases). Being one of the key lectins of innate and acquired immunity, gal-3 is generally considered a powerful pro-inflammatory signal. However, additional biological characterization of gal-3 is of utmost importance for elucidation of the mechanisms of the processes in which it is involved. The aim of this study was to ascertain the level of gal-3 expression and explore its role in (patho)physiological processes of monocytic lineage cells. We used lipopolysaccharide (LPS) activated and phorbol 12-myristate-13-acetate (PMA) differentiated, THP-1 cells and human monocytes isolated from the buffy coats of healthy volunteers. Flow cytometry and Western blot were used to determine gal-3 expression, while qRT-PCR was used to measure LGALS3 expression. Dead cells were excluded as 7AAD positive. Using cytokine capture beads and flow cytometry, we studied the effect of recombinant human gal-3 on inflammatory cytokine secretion of classically (M1) or alternatively activated (M2a/M2c) macrophage cells and on the expression of LGALS3. PBMC-derived monocytes from healthy volunteers were exposed to macrophage colony-stimulating factor (M-CSF), IFN- γ and LPS to generate M1 cells or granulocyte- macrophage colony-stimulating factor (GM-CSF) and IL-4/IL-10 to generate M2a/M2c cells. LPS-activated THP-1 cells had markedly up- regulated expression of intracellular gal-3, while the surface level remains largely unchanged. Differentiation of monocytes to macrophages is associated with an increase of surface and total gal-3 expression in respect to the controls. M1 polarization was confirmed by elevated TNF-α, IL- 1ß and IL-6 in culture medium and lack of CD206 mannose receptor in respect to M2 macrophages. Our data indicate IL-8 could be considered a novel M1 vs. M2 polarization marker. Exogenous gal-3 was shown to effect LGALS3 expression and to up- regulate IL-6 and IL-8 production in M2a cells and TNF-α, IL-6 and IL-8 production in M2c cells in respect to the control cells, thus skewing M2 cells towards the M1 pro-inflammatory phenotype. Although further research is needed, collected data provide new insights into gal-3 pro- inflammatory effects and could contribute setting up a platform for development of new anti- inflammatory therapeutic approaches.

galectin-3; monocytes; macrophages

doi: 10.1016/j.ejps.2011.08.002 ; http://dx.doi.org/10.1016/j.ejps.2011.08.002