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Figure 10 | Veterinary Research

Figure 10

From: Interleukin-1 signaling induced by Streptococcus suis serotype 2 is strain-dependent and contributes to bacterial clearance and inflammation during systemic disease in a mouse model of infection

Figure 10

Model of the mechanisms involved in S. suis-induced IL-1β production by bone marrow-derived dendritic cells (bmDCs). 1A: Strain-independent recognition of S. suis by bmDCs requires MyD88-dependent signaling and partially involves TLR2 activation via recognition of surface lipoproteins (LPs); 1B: If internalized, S. suis DNA and RNA can induce the production of IL-1β, possibly via recognition by endosomal receptors TLR7 and TLR9; 1C: Recognition of S. suis leads to activation of the NF-κB and MEK pathways for both strains, alongside p38 for SC84; 1D: Strains P1/7 and SC84 induce comparable transcription of IL-1β mRNA; 2A: For strain P1/7, low levels of suilysin (SLY) and other not yet identified bacterial components lead to partial NLRP3 and AIM2 inflammasome activation; 2B: Caspase-1 cleavage leads to maturation of moderate levels of IL-1β that are then secreted; 3A and 3B: For strain SC84, secretion of high levels of SLY induces an important K+ efflux, that results in an activation of multiple inflammasomes, including NLRP3, NLRP1, AIM2, and NLRC4; however, other bacterial components could also influence this activation. 3C: Increased caspase-1 cleavage leads to a more efficient maturation of the pro-IL-1β, resulting in the secretion of high levels of IL-1β.

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