Pseudomonas aeruginosa Homoserine Lactone Activates Store-operated cAMP and Cystic Fibrosis Transmembrane Regulator-dependent Cl− Secretion by Human Airway Epithelia
Bibliographic record
Abstract
The ubiquitous bacterium Pseudomonas aeruginosa frequently causes hospital-acquired infections. P. aeruginosa also infects the lungs of cystic fibrosis (CF) patients and secretes N-(3-oxo-dodecanoyl)-S-homoserine lactone (3O-C12) to regulate bacterial gene expression critical for P. aeruginosa persistence. In addition to its effects as a quorum-sensing gene regulator in P. aeruginosa, 3O-C12 elicits cross-kingdom effects on host cell signaling leading to both pro- or anti-inflammatory effects. We find that in addition to these slow effects mediated through changes in gene expression, 3O-C12 also rapidly increases Cl(-) and fluid secretion in the cystic fibrosis transmembrane regulator (CFTR)-expressing airway epithelia. 3O-C12 does not stimulate Cl(-) secretion in CF cells, suggesting that lactone activates the CFTR. 3O-C12 also appears to directly activate the inositol trisphosphate receptor and release Ca(2+) from the endoplasmic reticulum (ER), lowering [Ca(2+)] in the ER and thereby activating the Ca(2+)-sensitive ER signaling protein STIM1. 3O-C12 increases cytosolic [Ca(2+)] and, strikingly, also cytosolic [cAMP], the known activator of CFTR. Activation of Cl(-) current by 3O-C12 was inhibited by a cAMP antagonist and increased by a phosphodiesterase inhibitor. Finally, a Ca(2+) buffer that lowers [Ca(2+)] in the ER similar to the effect of 3O-C12 also increased cAMP and I(Cl). The results suggest that 3O-C12 stimulates CFTR-dependent Cl(-) and fluid secretion in airway epithelial cells by activating the inositol trisphosphate receptor, thus lowering [Ca(2+)] in the ER and activating STIM1 and store-operated cAMP production. In CF airways, where CFTR is absent, the adaptive ability to rapidly flush the bacteria away is compromised because the lactone cannot affect Cl(-) and fluid secretion.
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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) | 0.000 | 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".