Proinflammatory synergy between protease and superantigen streptococcal pyogenic exotoxins
Bibliographic record
Abstract
ABSTRACT Streptococcal pyogenic exotoxins (Spe proteins) secreted by Streptococcus pyogenes (group A Streptococcus , GAS) are responsible for scarlet fever and streptococcal toxic shock syndrome. Most Spes are superantigens that cause excessive inflammation by activating large numbers of T cells. However, Streptococcal pyogenic exotoxin B (SpeB) is an exception, which is pro-inflammatory through its protease activity. Prior work shows that SpeB has the potential to cleave bacterial proteins. If cleavage of superantigens results in their inactivation, this gives the possibility that these two classes of exotoxins work at cross-purposes. We examined SpeB cleavage of the 11 major GAS superantigens and found that lability was not specific to structure, conservation, or, when compared to orthologous superantigens from Staphylococcus aureus , species of origin. We further show that rather than strictly antagonizing superantigen activity through degradation, SpeB can synergistically enhance superantigen-induced inflammation. For SpeB-labile superantigens, such as SmeZ, this is limited due to degradation, but for protease-resistant superantigens like SpeA, activity remains synergistic even at high protease concentrations. These findings suggest two modes by which proteases like SpeB may post-translationally regulate superantigens: positively, as a force amplifier that cooperatively increases inflammation, and negatively, through degradation that could act as a rheostat-like mechanism to limit excessive immune activation. Both mechanisms may contribute to the pathogenesis of GAS and other superantigen-producing pathogens. IMPORTANCE Streptococcus pyogenes produces both superantigen and protease virulence factors to subvert host immunity. However, its major protease is highly promiscuous and would potentially limit superantigen activity through its degradation. We profile the sensitivity of the streptococcal superantigens to degradation by the protease SpeB, providing evidence that many are highly resistant. Furthermore, we show that these important toxins can have synergistic proinflammatory activity. This provides insight into diseases like scarlet fever and toxic shock syndrome caused by these toxins and suggests anti-inflammatories that may be therapeutically useful.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".