The Evidence Layer for Scientific AI

What is directionally supported vs missing

Supported directionality (general biology): Loss or dysfunction of HSD11B2 (11β-HSD2) abolishes conversion of cortisol to cortisone, allowing cortisol to activate MR and producing the biochemical/clinical pattern of apparent mineralocorticoid excess (AME). AME review: HSD11B2 loss disables cortisol→cortisone protection of MR

Not supported (for fibroblasts / collagen barrier in the provided evidence): None of the supplied sources directly measure in fibroblasts the cortisol→cortisone conversion rate (or directionality), nor do they experimentally connect fibroblast 11β-HSD2 to collagen barrier formation, ECM deposition, barrier permeability, or “directionality” of barrier function.

Evidence in the provided set that can be used cautiously

• System-level cortisol regulation (model organism): In a zebrafish hsd11b2 knockout, stress-associated cortisol is prolonged vs wild type in larvae, showing that Hsd11b2 impacts cortisol kinetics under stress. Zebrafish hsd11b2 KO prolongs cortisol stress response
• Cell-type regulatory context: HSD11B2 transcription is cell-type regulated (e.g., different mRNA levels across epithelial-like cell lines), consistent with the idea that fibroblasts may differ from other tissues. HSD11B2 promoter shows cell-type-specific regulation
• Signaling control in a specific human context: In human placental trophoblasts, hCG/cAMP and MAPK signaling influence HSD11B2 expression (p38 MAPK promotes; ERK1/2 opposes). This demonstrates regulation can be tissue- and pathway-specific, but it is not fibroblast-specific. Placental trophoblast signaling regulates HSD11B2 expression

Quantitative snapshot available from the provided dataset

The dataset includes zebrafish larval cortisol values (pg/larva ± SEM) at multiple stress time points; later points are missing for wild type (N/A), so the graph only plots reported values.

Scope limitations (what would be needed to answer the exact fibroblast+collagen barrier question)

To make “11β-HSD2 fibroblast cortisol→cortisone” and “collagen barrier directionality” scientifically answerable, the evidence set would need (i) fibroblast-specific 11β-HSD2 expression/kinetics and (ii) fibroblast ECM/barrier assays (e.g., collagen deposition/remodeling readouts and permeability or barrier-function measures) under manipulated cortisol/cortisone exposure or HSD11B2 perturbation.