The complement system is an integrated part of the natural innate immune response in the brain
Bibliographic record
Abstract
ABSTRACT The complement system consists of a group of proteins that play essential roles in coordinating the host defense to infection. It can be activated by two primary pathways, namely the classical and the alternative. This study aimed to determine the cellular distribution and the regulation of the genes encoding the proteins that are essential in guiding these pathways in the central nervous system (CNS) during innate immune recognition in mice. The results show a low‐to‐moderate C3 mRNA signal in few nonneuronal structures under basal conditions, whereas a robust C5 expression level was found in numerous populations of neuronal and nonneuronal cells. However, hybridization signal for the gene encoding the anaphylatoxin C5a receptor (C5aR) was low in the brain of vehicle‐administered mice. The constitutive C5 mRNA levels remained unaltered during endotoxemia, but a strong and transient de novo expression of the other members of the complement protein family was found in the brain of mice that received a single systemic bolus of lipopolysaccharide (LPS). Indeed, transcriptional activation C3 and factor B genes occurred in the circumventricular organs and a wave of C3aR‐expressing cells took place from the regions devoid of blood‐brain barrier to deeper brain parenchyma. The C5aR mRNA levels also increased in the cerebral endothelium at 1 h post‐LPS challenge, and the signal became gradually positive in microglial cells surrounding the capillaries and thereafter across the brain parenchyma. The present data provide evidence of an elegant pattern of expression and de novo transcription of key members of the complement system in the CNS, which underlies a sophisticated innate immune system that is triggered by circulating cell wall components of gram‐negative bacteria.
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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".