Alpha-synuclein shapes monocyte and macrophage cell biology and functions by bridging alterations of autophagy and inflammatory pathways
Articolo
Data di Pubblicazione:
2024
Citazione:
Alpha-synuclein shapes monocyte and macrophage cell biology and functions by bridging alterations of autophagy and inflammatory pathways / F. Limanaqi, S. Zecchini, P. Ogno, V. Artusa, C. Fenizia, I. Saulle, C. Vanetti, M. Garziano, S. Strizzi, D. Trabattoni, M. Clerici, M. Biasin. - In: FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY. - ISSN 2296-634X. - 12:(2024), pp. 1421360.1-1421360.22. [10.3389/fcell.2024.1421360]
Abstract:
Introduction: Abnormal spreading of alpha-synuclein (αS), a hallmark of Parkinson’s disease, is known to promote peripheral inflammation, which occurs in part via functional alterations in monocytes/macrophages. However, underlying intracellular mechanisms remain unclear.
Methods: Herein we investigate the subcellular, molecular, and functional effects of excess αS in human THP-1 monocytic cell line, THP-1-derived macrophages, and at least preliminarily, in primary monocyte-derived macrophages (MDMs). In cells cultured w/wo recombinant αS (1 μM) for 4 h and 24 h, by Confocal microscopy, Western Blot, RT-qPCR, Elisa, and Flow Cytometry we assessed: i) αS internalization; ii) cytokine/chemokine expression/secretion, and C–C motif chemokine receptor 2 (CCR2) levels; iii) autophagy (LC3II/I, LAMP1/LysoTracker, p62, pS6/total S6); and iv) lipid droplets (LDs) accumulation, and cholesterol pathway gene expression. Transwell migration assay was employed to measure THP-1 cell migration/chemotaxis, while FITC-IgG-bead assay was used to analyze phagocytic capacity, and the fate of phagocytosed cargo in THP-1-derived macrophages.
Results: Extracellular αS was internalized by THP-1 cells, THP-1-derived macrophages, and MDMs. In THP1 cells, αS induced a general pro-inflammatory profile and conditioned media from αS-exposed THP-1 cells potently attracted unstimulated cells. However, CCL2 secretion peaked at 4 h αS, consistent with early internalization of its receptor CCR2, while this was blunted at 24 h αS exposure, when CCR2 recycled back to the plasma membrane. Again, 4 h αS-exposed THP-1 cells showed increased spontaneous migration, while 24 h αS-exposed cells showed reduced chemotaxis. This occurred in the absence of cell toxicity and was associated with upregulation of autophagy/lysosomal markers, suggesting a pro-survival/tolerance mechanism against stress-related inflammation. Instead, in THP-1-derived macrophages, αS time-dependently potentiated the intracellular accumulation, and release of pro-inflammatory mediators. This was accompanied by mild toxicity, reduced autophagy-lysosomal markers, defective LDs formation, as well as impaired phagocytosis, and the appearance of stagnant lysosomes engulfed with phagocytosed cargo, suggesting a status of macrophage exhaustion reminiscent of hypophagia.
Discussion: In summary, despite an apparently similar pro-inflammatory phenotype, monocytes and macrophages respond differently to intracellular αS accumulation in terms of cell survival, metabolism, and functions. Our results suggest that in periphery, αS exerts cell- and context-specific biological effects bridging alterations of autophagy, lipid dynamics, and inflammatory pathways.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
cell survival; cell toxicity; p62; lysosomes; cell migration; chemotaxis; phagocytosis; lipid droplets
Elenco autori:
F. Limanaqi, S. Zecchini, P. Ogno, V. Artusa, C. Fenizia, I. Saulle, C. Vanetti, M. Garziano, S. Strizzi, D. Trabattoni, M. Clerici, M. Biasin
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