Mast Cells Impair Host Defense During Murine Streptococcus pneumoniae Pneumonia
Bibliographic record
Abstract
BACKGROUND: Streptococcus pneumoniae is the most common causative pathogen in community-acquired pneumonia. Mast cells (MCs) are located mainly at the host-environment interface where they function as sentinels. OBJECTIVE: Our goal was to study the role of MCs during pneumonia caused by S. pneumoniae. METHODS: Lung tissue of patients who had died from pneumococcal pneumonia or a nonpulmonary cause was stained for MCs and tryptase. Wild-type (WT) and MC-deficient (Kit(W-sh/W-sh)) mice were observed or sacrificed after induction of pneumonia by intranasal inoculation of S. pneumoniae. In separate experiments, WT mice were treated with doxantrazole or cromoglycate, which are MC stabilizing agents. RESULTS: The constitutive presence of tryptase-positive MCs was reduced in affected lungs from pneumonia patients. Kit(W-sh/W-sh) mice showed a prolonged survival during the first few days after median lethal dose (LD)100 and LD50 infection, while overall mortality did not differ from that in WT mice. Relative to WT mice, Kit(W-sh/W-sh) mice showed reduced bacterial counts with less bacterial dissemination to distant organs and less inflammation. Neither doxantrazole nor cromoglycate influenced antibacterial defense or inflammatory responses after airway infection with S. pneumoniae. CONCLUSIONS: MCs exhibit an unfavorable role in host defense during pneumococcal pneumonia by a mechanism independent of degranulation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".