Intrauterine oxygen milieu governs placental sphingolipid metabolism
Bibliographic record
Abstract
Early placentation relies on temporal changes in intrauterine oxygen tension that regulate trophoblast differentiation events. Studies have highlighted the contribution of bioactive sphingolipids to the pathogenesis of placental disorders, characterized by hypoxia. However, it is unknown whether placental sphingolipid metabolism changes during the switch from a hypoxic to an oxygenated environment in the first trimester of gestation and if sustained hypoxia is causative of sphingolipid alterations seen in preeclampsia. Herein, we performed sphingolipid analysis of first-trimester human placentae as well as placentae from conditional (placenta-specific) Phd2 knockout mice ( Phd2 −/− cKO) that exhibit preeclampsia-like features, including placental hypoxia. Analysis revealed elevated long chain ceramide (Cer16:0, Cer18:0, Cer20:0 and Cer22:0) and reduced sphingosine-1-phosphate (So-1-P) content in Phd2 −/− cKO placentae. Expression of key regulatory sphingolipid enzymes, acid ceramidase (ASAH1) and sphingosine kinase 1 (SPHK1), was reduced in Phd2 −/− cKO placentae, while that of alkaline ceramidase ACER2 remained unchanged. Human placentae from 5-9 weeks of gestation, when intrauterine oxygen tension is low, exhibited heightened long chain ceramide (Cer14:0, Cer16:0, Cer18:0, Cer 18:1) and sphingosine content and reduced ASAH1 and SPHK1 expression, highlighting the relevance of low oxygen in regulating sphingolipid metabolism under physiological (placental development) and pathological ( Phd2 −/− cKO induced preeclampsia) conditions. Ultrastructural analyses of early (5–9 weeks) human and murine Phd2 −/− cKO placentae revealed that increased trophoblast mitochondrial fission events accompanied elevated ceramide. Together, the data support the concept that a chronic low-oxygen environment leads to placental ceramide buildup, which may alter mitochondrial homeostasis and potentially contribute to cell death events characteristic of preeclampsia.
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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) | 0.001 | 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".