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Cigarette smoke-exposed neutrophils die unconventionally but are rapidly phagocytosed by macrophages.

Guzik K, Skret J, Smagur J, Bzowska M, Gajkowska B, Scott DA, Potempa JS - Cell Death Dis (2011)

Bottom Line: Accumulation of tar-like substances in autophagosomes is also apparent.Blockade of LOX-1 and scavenger receptor A, but not MARCO or CD36, as well as pre-incubation with oxLDL, inhibited phagocytosis, suggesting that oxLDL-like structures are major phagocytosis signals.Specific lipid (β-carotene and quercetin), but not aqueous, antioxidants increased the pro-phagocytic effects of CSE.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.

ABSTRACT
Pulmonary accumulation of neutrophils is typical for active smokers who are also predisposed to multiple inflammatory and infectious lung diseases. We show that human neutrophil exposure to cigarette smoke extract (CSE) leads to an atypical cell death sharing features of apoptosis, autophagy and necrosis. Accumulation of tar-like substances in autophagosomes is also apparent. Before detection of established cell death markers, CSE-treated neutrophils are effectively recognized and non-phlogistically phagocytosed by monocyte-derived macrophages. Blockade of LOX-1 and scavenger receptor A, but not MARCO or CD36, as well as pre-incubation with oxLDL, inhibited phagocytosis, suggesting that oxLDL-like structures are major phagocytosis signals. Specific lipid (β-carotene and quercetin), but not aqueous, antioxidants increased the pro-phagocytic effects of CSE. In contrast to non-phlogistic phagocytosis, degranulation of secondary granules, as monitored by lactoferrin release, was apparent on CSE exposure, which is likely to promote pulmonary inflammation and tissue degradation. Furthermore, CSE-exposed neutrophils exhibited a compromised ability to ingest the respiratory pathogen, Staphylococcus aureus, which likely contributes to bacterial persistence in the lungs of smokers and is likely to promote further pulmonary recruitment of neutrophils. These data provide mechanistic insight into the lack of accumulation of apoptotic neutrophil populations in the lungs of smokers and their increased susceptibility to degradative pulmonary diseases and bacterial infections.

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LOX1 and SR-A hMDM scavenger receptors are key mediators of CSE-exposed neutrophil recognition and engulfment by hMDMs. Control hMDMs and hMDMs pre-incubated (20 °C, 20 min) with mAbs specific for individual scavenger receptors (MARCO, CD36, SR-A and LOX1; all 10 μg/ml) and their capacity to phagocytose control (freshly isolated) and CSE-exposed neutrophils over 2 h established by measurement of the activity of internalized neutrophil elastase. Competitive inhibition by oxLDL (50 μg/ml) of phagocytosis of neutrophils pretreated with CSE in the presence and absence of β-carotene or quercetin was also assessed. Results are expressed as percentage of the positive (100%) established by monitoring phagocytosis of CSE-treated neutrophils. Data presented are mean (±S.D.). *P<0.05; ***P<0.001, compared with CSE only (100% control)
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fig5: LOX1 and SR-A hMDM scavenger receptors are key mediators of CSE-exposed neutrophil recognition and engulfment by hMDMs. Control hMDMs and hMDMs pre-incubated (20 °C, 20 min) with mAbs specific for individual scavenger receptors (MARCO, CD36, SR-A and LOX1; all 10 μg/ml) and their capacity to phagocytose control (freshly isolated) and CSE-exposed neutrophils over 2 h established by measurement of the activity of internalized neutrophil elastase. Competitive inhibition by oxLDL (50 μg/ml) of phagocytosis of neutrophils pretreated with CSE in the presence and absence of β-carotene or quercetin was also assessed. Results are expressed as percentage of the positive (100%) established by monitoring phagocytosis of CSE-treated neutrophils. Data presented are mean (±S.D.). *P<0.05; ***P<0.001, compared with CSE only (100% control)

Mentions: As shown in Figure 5, pre-incubation of hMDMs with oxLDL inhibited phagocytosis of CSE-exposed neutrophils by >60%. Furthermore, phagocytosis of CSE-pretreated neutrophils was even more efficiently blocked when oxLDL treatment was supplemented with β-carotene or quercetin. The oxLDL interference with phagocytosis implied involvement of scavenger receptors in the recognition of CSE-exposed neutrophils by macrophages. To verify the implication that hMDM scavenger receptors recognizing oxidized lipids were involved in the recognition and phagocytosis of CSE-treated neutrophils, specific mAbs known to block selected scavenger receptors (SR-A, MARCO, LOX1 and CD36) were employed. Although blockade of MARCO and CD36 suppressed the uptake of neutrophils in a limited manner, specific blocking of SR-A and LOX1 receptors inhibited phagocytosis by approximately 60 and 80%, respectively.


Cigarette smoke-exposed neutrophils die unconventionally but are rapidly phagocytosed by macrophages.

Guzik K, Skret J, Smagur J, Bzowska M, Gajkowska B, Scott DA, Potempa JS - Cell Death Dis (2011)

LOX1 and SR-A hMDM scavenger receptors are key mediators of CSE-exposed neutrophil recognition and engulfment by hMDMs. Control hMDMs and hMDMs pre-incubated (20 °C, 20 min) with mAbs specific for individual scavenger receptors (MARCO, CD36, SR-A and LOX1; all 10 μg/ml) and their capacity to phagocytose control (freshly isolated) and CSE-exposed neutrophils over 2 h established by measurement of the activity of internalized neutrophil elastase. Competitive inhibition by oxLDL (50 μg/ml) of phagocytosis of neutrophils pretreated with CSE in the presence and absence of β-carotene or quercetin was also assessed. Results are expressed as percentage of the positive (100%) established by monitoring phagocytosis of CSE-treated neutrophils. Data presented are mean (±S.D.). *P<0.05; ***P<0.001, compared with CSE only (100% control)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3101810&req=5

fig5: LOX1 and SR-A hMDM scavenger receptors are key mediators of CSE-exposed neutrophil recognition and engulfment by hMDMs. Control hMDMs and hMDMs pre-incubated (20 °C, 20 min) with mAbs specific for individual scavenger receptors (MARCO, CD36, SR-A and LOX1; all 10 μg/ml) and their capacity to phagocytose control (freshly isolated) and CSE-exposed neutrophils over 2 h established by measurement of the activity of internalized neutrophil elastase. Competitive inhibition by oxLDL (50 μg/ml) of phagocytosis of neutrophils pretreated with CSE in the presence and absence of β-carotene or quercetin was also assessed. Results are expressed as percentage of the positive (100%) established by monitoring phagocytosis of CSE-treated neutrophils. Data presented are mean (±S.D.). *P<0.05; ***P<0.001, compared with CSE only (100% control)
Mentions: As shown in Figure 5, pre-incubation of hMDMs with oxLDL inhibited phagocytosis of CSE-exposed neutrophils by >60%. Furthermore, phagocytosis of CSE-pretreated neutrophils was even more efficiently blocked when oxLDL treatment was supplemented with β-carotene or quercetin. The oxLDL interference with phagocytosis implied involvement of scavenger receptors in the recognition of CSE-exposed neutrophils by macrophages. To verify the implication that hMDM scavenger receptors recognizing oxidized lipids were involved in the recognition and phagocytosis of CSE-treated neutrophils, specific mAbs known to block selected scavenger receptors (SR-A, MARCO, LOX1 and CD36) were employed. Although blockade of MARCO and CD36 suppressed the uptake of neutrophils in a limited manner, specific blocking of SR-A and LOX1 receptors inhibited phagocytosis by approximately 60 and 80%, respectively.

Bottom Line: Accumulation of tar-like substances in autophagosomes is also apparent.Blockade of LOX-1 and scavenger receptor A, but not MARCO or CD36, as well as pre-incubation with oxLDL, inhibited phagocytosis, suggesting that oxLDL-like structures are major phagocytosis signals.Specific lipid (β-carotene and quercetin), but not aqueous, antioxidants increased the pro-phagocytic effects of CSE.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.

ABSTRACT
Pulmonary accumulation of neutrophils is typical for active smokers who are also predisposed to multiple inflammatory and infectious lung diseases. We show that human neutrophil exposure to cigarette smoke extract (CSE) leads to an atypical cell death sharing features of apoptosis, autophagy and necrosis. Accumulation of tar-like substances in autophagosomes is also apparent. Before detection of established cell death markers, CSE-treated neutrophils are effectively recognized and non-phlogistically phagocytosed by monocyte-derived macrophages. Blockade of LOX-1 and scavenger receptor A, but not MARCO or CD36, as well as pre-incubation with oxLDL, inhibited phagocytosis, suggesting that oxLDL-like structures are major phagocytosis signals. Specific lipid (β-carotene and quercetin), but not aqueous, antioxidants increased the pro-phagocytic effects of CSE. In contrast to non-phlogistic phagocytosis, degranulation of secondary granules, as monitored by lactoferrin release, was apparent on CSE exposure, which is likely to promote pulmonary inflammation and tissue degradation. Furthermore, CSE-exposed neutrophils exhibited a compromised ability to ingest the respiratory pathogen, Staphylococcus aureus, which likely contributes to bacterial persistence in the lungs of smokers and is likely to promote further pulmonary recruitment of neutrophils. These data provide mechanistic insight into the lack of accumulation of apoptotic neutrophil populations in the lungs of smokers and their increased susceptibility to degradative pulmonary diseases and bacterial infections.

Show MeSH
Related in: MedlinePlus