Complement Activation as a Distinctive Biomarker of Pediatric Idiopathic Nephrotic Syndrome: Differentiating FSGS from Minimal Change Disease and Evidence of Podocyte Involvement
Bibliographic record
Abstract
Background: Idiopathic Nephrotic Syndrome (INS) affects 2 to 16.9 per 100,000 children worldwide. INS is classified into Minimal Change Disease (MCD), often steroid-sensitive, and Focal Segmental Glomerulosclerosis (FSGS), frequently steroid-resistant. Previously, we identified urinary C5b-9 as a potential biomarker to differentiate FSGS from MCD in adult primary and secondary nephrotic syndromes, with FSGS patients exhibiting higher levels. However, its role in pediatric INS remains unexplored. Here, we assess urinary and plasma C5b-9 levels in pediatric INS patients with biopsy-confirmed FSGS or MCD. For the first time we investigate complement activation on podocytes stimulated with INS patient serum to better understand C5b-9’s role in podocyte injury and in INS pathology. Methods: We recruited only primary INS pediatric patients that hadproteinuria above 1 g/g of creatinine and albuminemia below 30g/L. Plasma and urinary C5b-9 levels were measured using ELISA. Human podocytes were stimulated with patient serum, and C5b-9 deposition was visualized using immunofluorescence microscopy. Immunohistochemistry was performed on kidney biopsies to assess C5b-9 localization. Results: Patients with FSGS had a serum albumin of 28 ± 8 g/L and urinary protein on creatinine ratio (UPCR) of 0.85 g/mmol, while those with MCD had a higher serum albumin (30 ± 13 g/L), and UPCR (0.92g/mmol). Urinary sC5b-9 levels were higher in FSGS patients compared to MCD (p=0.0114), while plasma levels remained similar. Immunofluorescence revealed robust C5b-9 deposition on podocytes treated with FSGS serum, whereas those treated with MCD serum showed minimal staining. Immunohistochemistry further supported these findings, with strong C5b-9 staining observed in FSGS kidney biopsies but absent in MCD. Conclusion: This study is the first to demonstrate C5b-9 deposition on podocytes following stimulation with FSGS patient serum. Urinary sC5b-9 may serve as a non-invasive biomarker for distinguishing FSGS from MCD in pediatric INS and monitoring disease progression. With further studies it may also be a good marker for active FSGS disease. Further research is needed to clarify complement activation mechanisms and their therapeutic implications.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".