Epithelial and Endothelial Expressions of ACE2: SARS-CoV-2 Entry Routes
Bibliographic record
Abstract
Angiotensin converting enzyme 2 (ACE2) is a main receptor for SARS-CoV-2 entry to the host cell. ACE2 is one of the key enzymes in renin-angiotensin system and plays a vital role in the maintenance of cardiovascular function. ACE/ACE2 balance is critical in the regulation of blood pressure, electrolyte homeostasis, vascular and cardiac remodeling and inflammation. ACE2 was shown to be abundantly present in human epithelial cells of the lung and enterocytes of the small intestine as well as in endothelial cells of the arterial and venous vessels. ACE2 and TMPRSS2 are colocalized on the cell surface and produced a critical step host cell entry of SARS-CoV-2. TMPRSS2-cleaved ACE2 permits SARS-CoV-2 host cell entry however, ADAM17-cleaved ACE2 produces protective effects in several organs. Differently, basigin (CD147) was suggested as a putative alternate receptor for SARS-CoV-2 entry into endothelial cells. The intestinal ACE2 receptor is associated with the neutral amino acid transporter B0AT1 and ACE2 is necessary for the expression of this transporter on the luminal surface of intestinal epithelial cells. There is a good association between the localization of SARS-CoV-2 binding receptor ACE2 and the disease target organs in respiratory, cardiovascular and gastrointestinal systems. Decreased expression of ACE2, being a receptor for coronavirus, would prevent cellular entry of the virus thereby reducing progression of the infection. However, increased ACE2 expression produces beneficial health effects. Further studies are needed to clarify this conflicting situation. Currently, it is recommended to continue the therapy with ACE2-increasing drugs in patients with COVID-19.
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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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".