Reinartz, D. M. | Search bioRxiv

bioRxiv2025

Streptococcus anginosus Activates the NLRP3 Inflammasome to Promote Inflammatory Responses from Macrophages

Chronic inflammation and oral dysbiosis are common features of oral squamous cell carcinoma (OSCC). The commensal streptococci, S. anginosus, is increased in oral diseases including OSCC. Our previous work revealed that S. anginosus promotes inflammatory responses from macrophage cell lines, however the molecular mechanism by which S. anginosus interacts with macrophages to instigate this response remains to be investigated. Here, we expand on our previous findings by investigating the effects of S. anginosus infection of primary bone marrow derived macrophages (BMMs) and during in vivo infection. We found S. anginosus activated primary BMMs, which presented an enlarged cellular area, increased NF-{kappa}B activation and downstream inflammatory cytokines TNF, IL-6 and IL-1{beta} at 24 hours post infection. S. anginosus viability was dispensable for NF-{kappa}B activation, but essential for the induction of downstream inflammatory proteins and cytokines. S. anginosus persisted intracellularly within BMMs and induced the expression of inflammasome sensors AIM2, NLRC4 and NLRP3. Further, BMMs lacking the inflammasome adapter protein ASC (Asc-/-) had significantly diminished IL-1{beta} production compared to wild type BMMs, indicating that S. anginosus activated the inflammasome. S. anginosus primarily triggered the inflammasome through NLRP3 as S. anginosus-infected Nlrp3-/- BMMs and NLRP3 inhibitor (MCC950)-treated wild type BMMs displayed diminished IL-1{beta} production compared to wild type controls. Lastly, S. anginosus-infected Asc-/- and Nlrp3-/-mice displayed reduced weight loss compared to C57BL/6 mice. These overall findings indicate that S. anginosus replicates within macrophages and promotes a proinflammatory response in part through activation of the NLRP3 inflammasome. brief summary sentence: S. anginosus replicates intracellularly within macrophages and is sensed by the NLRP3 inflammasome to promote proinflammatory response.

immunology↗

bioRxiv2024

Impact of AIM2 on HNSCC Development

Head and neck squamous cell carcinoma (HNSCC) constitutes 90% of head and neck cancers. HNSCC development is linked to chronic inflammation, while established HNSCC tumors are often immune suppressive. However, both occur through mechanisms that are not fully understood. The cytosolic double-stranded DNA sensor Absent in Melanoma 2 (AIM2) is an inflammasome forming protein that also has inflammasome-distinct roles in restricting tumorigenesis by limited PI3K signaling. Here, we used an experimental mouse model of HNSCC, involving treatment of wild type (WT) and Aim2-/-mice with the carcinogen 4NQO in drinking water. Compared to WT mice, 4NQO-treated Aim2-/- mice exhibited larger tumor sizes and increased tissue dysplasia. 4NQO-treated wild type and Aim2-/- mice displayed similar tongue Il6, Tnf, Il1b, Il12, and Il10 expression and no consistent differences in PI3K or inflammasome activation, suggesting AIM2 may not regulate these factors during HNSCC. Instead, Ifng and Irf1 was elevated in 4NQO-treated Aim2-/- mice, suggesting AIM2 restricts IFN{gamma}. In line with this, RNA-sequencing of total tongue RNA from 4NQO-treated mice revealed Aim2-/- mice had enhanced expression of genes related to the MHC protein complex, cell killing, and T cell activation compared to wild type mice. In addition, we observed increased macrophage infiltration into the tongue epithelium of 4NQO-treated Aim2-/- mice. Lastly, using Aim2-/-/Rag1-/--double deficient animals, we found that the adaptive immune compartment was necessary for the enhanced tumorigenesis during AIM2 deficiency. Taken together, these findings suggest AIM2 limits the progression of oral tumor development partially through regulating IFN{gamma} and adaptive immune responses.

immunology↗