Macrophage LC3-associated phagocytosis is an immune defense against Streptococcus pneumoniae that diminishes with host aging.
Proc Natl Acad Sci U S A
; 117(52): 33561-33569, 2020 12 29.
Article
em En
| MEDLINE
| ID: mdl-33376222
ABSTRACT
Streptococcus pneumoniae is a leading cause of pneumonia and invasive disease, particularly, in the elderly. S. pneumoniae lung infection of aged mice is associated with high bacterial burdens and detrimental inflammatory responses. Macrophages can clear microorganisms and modulate inflammation through two distinct lysosomal trafficking pathways that involve 1A/1B-light chain 3 (LC3)-marked organelles, canonical autophagy, and LC3-associated phagocytosis (LAP). The S. pneumoniae pore-forming toxin pneumolysin (PLY) triggers an autophagic response in nonphagocytic cells, but the role of LAP in macrophage defense against S. pneumoniae or in age-related susceptibility to infection is unexplored. We found that infection of murine bone-marrow-derived macrophages (BMDMs) by PLY-producing S. pneumoniae triggered Atg5- and Atg7-dependent recruitment of LC3 to S. pneumoniae-containing vesicles. The association of LC3 with S. pneumoniae-containing phagosomes required components specific for LAP, such as Rubicon and the NADPH oxidase, but not factors, such as Ulk1, FIP200, or Atg14, required specifically for canonical autophagy. In addition, S. pneumoniae was sequestered within single-membrane compartments indicative of LAP. Importantly, compared to BMDMs from young (2-mo-old) mice, BMDMs from aged (20- to 22-mo-old) mice infected with S. pneumoniae were not only deficient in LAP and bacterial killing, but also produced higher levels of proinflammatory cytokines. Inhibition of LAP enhanced S. pneumoniae survival and cytokine responses in BMDMs from young but not aged mice. Thus, LAP is an important innate immune defense employed by BMDMs to control S. pneumoniae infection and concomitant inflammation, one that diminishes with age and may contribute to age-related susceptibility to this important pathogen.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fagocitose
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Streptococcus pneumoniae
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Envelhecimento
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Interações Hospedeiro-Patógeno
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Macrófagos
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Proteínas Associadas aos Microtúbulos
Tipo de estudo:
Risk_factors_studies
Limite:
Animals
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2020
Tipo de documento:
Article