[Taurine inhibits M2 polarization of macrophages by promoting mitophagy].

Objective To investigate the molecular mechanism of taurine regulating the polarization of M2 macrophages by mitophagy. Methods THP-1 cells were divided into four groups: M0 group (THP-1 cells were treated by 100 nmol/L phorbol myristate ester for 48 hours to polarize into M0), M2 group (THP-1 cells were induced to polarize into M2 macrophages by 20 ng/mL interferon-4 (IL-4) for 48 hours), M2 combined with taurine groups (added with 40 or 80 mmol/L taurine on the basis of M2 macrophages). The mRNA expression of mannose receptor C type 1(MRC-1), C-C motif chemokine ligand 22(CCL22) and dendritic cell-specific ICAM-3 grabbing non-integrin (CD209) in M2 macrophages were detected by quantitative real-time PCR. Mitochondrial and lysosome probes were used to detect the number of mitochondria and lysosomes by multifunction microplate reader and confocal laser scanning microscope. The level of mitochondrial membrane potential (MMP) was detected by JC-1 MMP assay kit. The expression of mitophagy-related proteins PTEN-induced putative kinase 1 (PINK1) and microtubule-associated protein 1 light chain 3 (LC3) were detected by Western blot analysis. Results Compared with M0 group, the expression of MRC-1, CCL22, CD209 and PINK1, the number of mitochondria and the level of MMP in M2 group were significantly increased, whereas the number of lysosomes and LC3II/LC3I ratio were decreased. Compared with M2 group, the expressions of MRC-1, CCL22 and CD209, the number of mitochondria and the level of MMP in M2 combined with taurine group dropped significantly while the number of lysosomes was found increased, and the protein expression of PINK1 and LC3II/LC3I ratio were also increased. Conclusions The polarization of M2 macrophages is regulated by taurine to prevent excessive polarization via reducing the level of MMP, improving the level of mitophagy, reducing the number of mitochondria, and inhibiting the mRNA expression of polarization markers in M2 macrophages.

[Inhibition of demethylation of protein phosphatase 2A catalytic subunit (PP2Ac) promotes M1 polarization of macrophages].

Objective To investigate the role of demethylation of protein phosphatase 2A catalytic subunit (PP2Ac) on M1 macrophage polarization. Methods THP-1 cells were induced to differentiate into M0 macrophages with phorbol ester (PMA) for 24 hours, and then stimulated to differentiate into M1 macrophages induced by lipopolysaccharide (LPS) and interferon-γ (IFN-γ) for 48 hours. The administration group and the solvent control group were respectively cultured with 0.5 µmol/L ABL127 and the same volume of DMSO for 48 hours on M1 macrophage polarization models. Inverted microscope was used to observe the morphological changes of macrophages. The mRNA expression levels of cyclooxygenase 2 (COX-2), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and C-X-C motif chemokine ligand 10 (CXCL10) in M1 macrophages were detected by quantitative real-time PCR. M1 macrophage phagocytosis was determined by neutral red uptake assay. Western blot analysis was applied to test the level of PP2Ac demethylation. Results In the differentiation of M0 into M1 macrophages, the cells were elongated and became spindle-shaped. Furthermore, the expression of M1 macrophage markers including COX-2, TNF-α, IL-6 and CXCL10 significantly increased and phagocytosis was enhanced, but PP2Ac demethylation was decreased. Compared with the DMSO group, PP2Ac demethylation decreased while spindle cells, phagocytosis, and the mRNA levels of COX-2, TNF-α, IL-6 and CXCL10 significantly increased in the administration group with 0.5 µmol/L ABL127. Conclusion The inhibition of PP2Ac demethylation promotes the differentiation of M1 macrophages, and increases the expression of pro-inflammatory cytokines and the phagocytosis.