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CD14 signaling mediates lung immunopathology and mice mortality induced by Achromobacter xylosoxidans
Jefferson Elias-Oliveira1,2, Morgana Kelly Borges Prado1,3, Camila Oliveira Silva Souza1
1Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, 14040-903, Brazil.
Objective And Design:
Our research aimed to investigate the role of CD14 in pulmonary infection by Achromobacter xylosoxidans in an experimental murine model.
Methods:
C57Bl/6 or CD14-deficient mice were infected intratracheally with non-lethal inoculum of A. xylosoxidans. At times 1, 3 and 7 days after infection, lungs, bronchoalveolar lavage and blood were collected. CD14 gene expression was determined by RT-PCR. The bacterial load in the lungs was assessed by counting colony forming units (CFU). Cytokines, chemokines, lipocalin-2 and sCD14 were quantified by the ELISA method. Inflammatory infiltrate was observed on histological sections stained with HE, and leukocyte subtypes were assessed by flow cytometry. In another set of experiments, C57Bl/6 or CD14-deficient mice were inoculated with lethal inoculum and the survival rate determined.
Results:
CD14-deficient mice are protected from A. xylosoxidans-induced death, which is unrelated to bacterial load. The lungs of CD14-deficient mice presented a smaller area of tissue damage, less neutrophil and macrophage infiltration, less pulmonary edema, and a lower concentration of IL-6, TNF-α, CXCL1, CCL2 and CCL3 when compared with lungs of C57Bl/6 mice. We also observed that A. xylosoxidans infection increases the number of leukocytes expressing mCD14 and the levels of sCD14 in BALF and serum of C57Bl/6-infected mice.
Conclusions:
In summary, our data show that in A. xylosoxidans infection, the activation of CD14 induces intense pulmonary inflammatory response resulting in mice death.
Insights
Mice lacking CD14 (cluster of differentiation 14) are protected against Achromobacter xylosoxidans lung infection. CD14 activation drives severe inflammation and mortality in this bacterial pneumonia model.
Area of Science:
- Immunology
- Microbiology
- Pulmonary Medicine
Background:
- Achromobacter xylosoxidans is an opportunistic pathogen causing severe lung infections.
- CD14 (cluster of differentiation 14) is a key pattern recognition receptor involved in innate immunity.
Purpose of the Study:
- To investigate the role of CD14 in experimental pulmonary infection with A. xylosoxidans.
- To determine the impact of CD14 deficiency on host response and survival during A. xylosoxidans pneumonia.
Main Methods:
- Utilized a murine model of A. xylosoxidans intratracheal infection, comparing wild-type (C57Bl/6) and CD14-deficient mice.
- Assessed bacterial load (CFU), gene expression (RT-PCR), cytokine/chemokine levels (ELISA), and inflammatory cell infiltration (histology, flow cytometry).
- Determined survival rates following lethal A. xylosoxidans challenge.
Main Results:
- CD14-deficient mice exhibited significantly improved survival rates compared to wild-type mice.
- Absence of CD14 reduced lung tissue damage, neutrophil and macrophage infiltration, edema, and pro-inflammatory cytokines (IL-6, TNF-α).
- A. xylosoxidans infection upregulated membrane CD14 expression on leukocytes and soluble CD14 levels in bronchoalveolar lavage fluid and serum.
Conclusions:
- CD14 activation exacerbates pulmonary inflammation during A. xylosoxidans infection.
- Targeting CD14 may represent a therapeutic strategy for managing severe bacterial pneumonia.
