TY - JOUR

T1 - Bacterial aggregate size determines phagocytosis efficiency of polymorphonuclear leukocytes

AU - Alhede, Maria

AU - Lorenz, Melanie

AU - Fritz, Blaine Gabriel

AU - Jensen, Peter Østrup

AU - Ring, Hans Christian

AU - Bay, Lene

AU - Bjarnsholt, Thomas

PY - 2020

Y1 - 2020

N2 - The ability of bacteria to aggregate and form biofilms impairs phagocytosis by polymorphonuclear leukocytes (PMNs). The aim of this study was to examine if the size of aggregates is critical for successful phagocytosis and how bacterial biofilms evade phagocytosis. We investigated the live interaction between PMNs and Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Staphylococcus epidermidis using confocal scanning laser microscopy. Aggregate size significantly affected phagocytosis outcome and larger aggregates were less likely to be phagocytized. Aggregates of S. epidermidis were also less likely to be phagocytized than equally-sized aggregates of the other three species. We found that only aggregates of approx. 5 μm diameter or smaller were consistently phagocytosed. We demonstrate that planktonic and aggregated cells of all four species significantly reduced the viability of PMNs after 4 h of incubation. Our results indicate that larger bacterial aggregates are less likely to be phagocytosed by PMNs and we propose that, if the aggregates become too large, circulating PMNs may not be able to phagocytose them quickly enough, which may lead to chronic infection.

AB - The ability of bacteria to aggregate and form biofilms impairs phagocytosis by polymorphonuclear leukocytes (PMNs). The aim of this study was to examine if the size of aggregates is critical for successful phagocytosis and how bacterial biofilms evade phagocytosis. We investigated the live interaction between PMNs and Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Staphylococcus epidermidis using confocal scanning laser microscopy. Aggregate size significantly affected phagocytosis outcome and larger aggregates were less likely to be phagocytized. Aggregates of S. epidermidis were also less likely to be phagocytized than equally-sized aggregates of the other three species. We found that only aggregates of approx. 5 μm diameter or smaller were consistently phagocytosed. We demonstrate that planktonic and aggregated cells of all four species significantly reduced the viability of PMNs after 4 h of incubation. Our results indicate that larger bacterial aggregates are less likely to be phagocytosed by PMNs and we propose that, if the aggregates become too large, circulating PMNs may not be able to phagocytose them quickly enough, which may lead to chronic infection.

KW - Chronic bacterial infection

KW - E. coli

KW - P. aeruginosa

KW - Phagocytosis

KW - Polymorphonuclear leukocytes (PMNs)

KW - S. aureus

KW - S. epidermidis

U2 - 10.1007/s00430-020-00691-1

DO - 10.1007/s00430-020-00691-1

M3 - Journal article

C2 - 32880037

AN - SCOPUS:85090088733

VL - 209

SP - 669

EP - 680

JO - Zeitschrift fur medizinische Mikrobiologie und Immunologie

JF - Zeitschrift fur medizinische Mikrobiologie und Immunologie

SN - 0300-8584

ER -