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Contrasting phagosome pH regulation and maturation in human M1 and M2 macrophages.

Canton J, Khezri R, Glogauer M, Grinstein S - Mol. Biol. Cell (2014)

Bottom Line: The paucity of V-ATPases in M1 phagosomes was associated with, and likely caused by, delayed fusion with late endosomes and lysosomes.The delayed kinetics of maturation was, in turn, promoted by the failure of M1 phagosomes to acidify.By contrast, M2 phagosomes proceed to acidify immediately in order to clear apoptotic bodies rapidly and effectively.

View Article: PubMed Central - PubMed

Affiliation: Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.

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Phagosomal pH oscillations in M1 macrophages. (A) M1 macrophages were challenged with SNARF1-SOZ, and, upon particle uptake, pH measurements were acquired every minute for 30 min. The leftmost trace represents the mean ± SEM of 16 determinations. Three individual experiments are shown to the right of the averaged trace, to highlight the characteristic pH oscillations. (B) M1 macrophages were challenged with SNARF1-SOZ in the presence of 100 μM Zn2+. The leftmost trace represents the mean ± SEM of eight determinations. Three individual experiments are shown to the right of the averaged trace.
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Figure 6: Phagosomal pH oscillations in M1 macrophages. (A) M1 macrophages were challenged with SNARF1-SOZ, and, upon particle uptake, pH measurements were acquired every minute for 30 min. The leftmost trace represents the mean ± SEM of 16 determinations. Three individual experiments are shown to the right of the averaged trace, to highlight the characteristic pH oscillations. (B) M1 macrophages were challenged with SNARF1-SOZ in the presence of 100 μM Zn2+. The leftmost trace represents the mean ± SEM of eight determinations. Three individual experiments are shown to the right of the averaged trace.

Mentions: Whereas the phagosomal pH in M1 macrophages was routinely more alkaline than that of M2 macrophages, it was not constant over time. The variability, which is discernible in the averaged results illustrated in Figure 1A (replicated for reference in Supplemental Figure S4A), becomes more manifest when individual experiments are displayed (Supplemental Figure S4A). Such pH oscillations were unique to M1 phagosomes, as they were never observed in M2 phagosomes (Supplemental Figure S5A). Because fluorescein is best suited for pH measurements near its pKa (6.3), we confirmed the occurrence of oscillations near and above neutral pH using SOZ covalently labeled with SNARF1 (pKa = 7.5), a fluorophore better suited for pH determinations in the alkaline range (Figure 6A).


Contrasting phagosome pH regulation and maturation in human M1 and M2 macrophages.

Canton J, Khezri R, Glogauer M, Grinstein S - Mol. Biol. Cell (2014)

Phagosomal pH oscillations in M1 macrophages. (A) M1 macrophages were challenged with SNARF1-SOZ, and, upon particle uptake, pH measurements were acquired every minute for 30 min. The leftmost trace represents the mean ± SEM of 16 determinations. Three individual experiments are shown to the right of the averaged trace, to highlight the characteristic pH oscillations. (B) M1 macrophages were challenged with SNARF1-SOZ in the presence of 100 μM Zn2+. The leftmost trace represents the mean ± SEM of eight determinations. Three individual experiments are shown to the right of the averaged trace.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4214780&req=5

Figure 6: Phagosomal pH oscillations in M1 macrophages. (A) M1 macrophages were challenged with SNARF1-SOZ, and, upon particle uptake, pH measurements were acquired every minute for 30 min. The leftmost trace represents the mean ± SEM of 16 determinations. Three individual experiments are shown to the right of the averaged trace, to highlight the characteristic pH oscillations. (B) M1 macrophages were challenged with SNARF1-SOZ in the presence of 100 μM Zn2+. The leftmost trace represents the mean ± SEM of eight determinations. Three individual experiments are shown to the right of the averaged trace.
Mentions: Whereas the phagosomal pH in M1 macrophages was routinely more alkaline than that of M2 macrophages, it was not constant over time. The variability, which is discernible in the averaged results illustrated in Figure 1A (replicated for reference in Supplemental Figure S4A), becomes more manifest when individual experiments are displayed (Supplemental Figure S4A). Such pH oscillations were unique to M1 phagosomes, as they were never observed in M2 phagosomes (Supplemental Figure S5A). Because fluorescein is best suited for pH measurements near its pKa (6.3), we confirmed the occurrence of oscillations near and above neutral pH using SOZ covalently labeled with SNARF1 (pKa = 7.5), a fluorophore better suited for pH determinations in the alkaline range (Figure 6A).

Bottom Line: The paucity of V-ATPases in M1 phagosomes was associated with, and likely caused by, delayed fusion with late endosomes and lysosomes.The delayed kinetics of maturation was, in turn, promoted by the failure of M1 phagosomes to acidify.By contrast, M2 phagosomes proceed to acidify immediately in order to clear apoptotic bodies rapidly and effectively.

View Article: PubMed Central - PubMed

Affiliation: Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.

Show MeSH
Related in: MedlinePlus