Neutrophil dysfunction and activation of the absent in melanoma 2 (AIM2) inflammasome have been implicated in ulcerative colitis (UC) pathogenesis. However, whether these two immune responses interact synergistically and their precise role in UC remains unclear. Here, we performed bioinformatics and clinical analyses to assess neutrophil extracellular traps (NETs) and AIM2 inflammasome cascades in UC, including their correlation. Dual immunofluorescence revealed the predominant cell types expressing AIM2. Neutrophil activation and NETs release were examined in Fusobacterium nucleatum ( Fn )-stimulated cell models, while in vitro and in vivo studies investigated the effect of NETs on AIM2 inflammasome activation, UC severity, and therapeutic potential. Bioinformatics revealed co-up-regulation and significant co-expression of AIM2 inflammasome cascade-related genes and NETs-related genes in active UC. Confocal imaging showed that AIM2 primarily localized to intestinal epithelial cells in intestinal biopsies from UC patients and colon tissues from UC model mice. Fn infection partially promoted neutrophil activation and the release of NETs via neutrophil extracellular vesicles (nEVs). NETs were carried by nEVs and internalized by intestinal epithelial cells, subsequently triggering AIM2 inflammasome-dependent pyroptosis. In vivo studies demonstrated that elevated AIM2 inflammasome-related indicators triggered by Fn -stimulated nEVs-NETs were related to UC severity. Therapeutically, blockade of the nEVs-NETs/AIM2 inflammasome cascade using the NET-degrading agent DNase I or the AIM2 inhibitor A151 effectively attenuated colitis. Collectively, AIM2 inflammasome cascade activation by NETs-laden nEVs triggered by Fn exacerbates ulcerative colitis, highlighting the nEVs-NETs/AIM2 inflammasome cascade as a promising therapeutic target.
Moyamoya disease (MMD) is a progressive cerebrovascular disorder characterized by arterial stenosis and compensatory neovascularization, but its upstream drivers remain poorly defined. Here, we identify Bifidobacterium pseudocatenulatum (B. pseudocatenulatum), a traditionally probiotic species, as a context-dependent pathobiont. Integrated metagenomic and metabolomic analyses revealed enrichment of B. pseudocatenulatum in MMD, closely associated with elevated microbial-derived histamine and serotonin. In mice, chronic oral administration of B. pseudocatenulatum disrupted intestinal barrier integrity and increased gut microbial production and systemic levels of histamine and serotonin. These changes were accompanied by systemic inflammation and activation of angiogenic pathways, which together promoted MMD-relevant cerebrovascular remodeling in experimental models. Notably, direct administration of histamine or serotonin to mice reproduced key MMD-like vascular phenotypes, supporting the conclusion that these microbial metabolites are sufficient to induce selected MMD-relevant vascular changes in experimental models. Our findings propose a microbial–metabolite–vascular axis and suggest that the role of specific Bifidobacterium strains may be more nuanced than previously recognized. These results provide a mechanistic framework for understanding the gut–brain axis in neurovascular pathology and nominate the microbiome and its metabolic products as potential targets for non-invasive diagnostics and precision therapeutic interventions in MMD.
Bone morphogenetic protein 2 (BMP2) has the potential to drive multipotent mesenchymal stem cells (MSCs) to undergo chondral–osteogenic (including hypertrophic chondrocyte) differentiation. Parathyroid hormone-related protein (PTHrP) plays an essential role in fetal endochondral ossification, although persistent PTHrP stimulation leads to postnatal bone loss. Here, we investigated the effects of PTHrP on BMP2-induced endochondral ossification through hypertrophic chondrocyte differentiation of MSCs. We found that silencing PTHrP expression inhibited BMP2-induced chondrogenic, hypertrophic, and osteogenic differentiation of MSCs, while overexpression of PTHrP promoted BMP2-induced chondrogenic differentiation of MSCs and suppressed BMP2-induced hypertrophic differentiation of MSCs. Using stem cell implantation studies in athymic nude mice, we demonstrated that while MSCs with silenced PTHrP expression exhibited significantly reduced endochondral ossification of subcutaneous cartilage, overexpression of PTHrP promoted the growth of subcutaneous cartilage while significantly delaying ossification, leading to the preservation of cartilage phenotype. Mechanistically, we showed that exogenous PTHrP promoted BMP2-induced chondrogenic differentiation of MSCs by up-regulating Sox9 expression and inactivating PI3K–AKT signaling. Collectively, our findings strongly suggest that PTHrP may play an important role in mediating BMP2-induced chondral-osteogenic differentiation of MSCs by inactivating PI3K–AKT signaling, indicating that PTHrP may be exploited for endochondral cartilage-bone tissue engineering.
The pathogenic role of the intestinal microenvironment on Hirschsprung's disease (HSCR) is increasingly recognized; however, the spatial expression patterns and underlying molecular mechanisms of the HSCR intestinal microenvironment remain unclear. In this study, we generated the first comprehensive spatial transcriptomic map of HSCR and revealed microenvironmental heterogeneity. Spatial transcriptomics revealed THBS1 as a consistently down-regulated gene in HSCR aganglionic segments. In vitro experiments using THP-1 and SH-SY5Y cells showed that THBS1 promoted M2-like polarization and interacted with SDC1. Furthermore, THBS1-overexpressing macrophages enhanced the proliferation and migration of SH-SY5Y cells in co-culture. These findings suggest a potential role for THBS1 in modulating macrophage–neural interactions in the HSCR microenvironment, though further validation in primary cells is needed.
Small RNAs (sRNAs) act as critical regulators of post-transcriptional activity and diverse cellular processes in bacteria. However, the entire repertoire of sRNAs and their functions has not yet been extensively studied. This study employs a novel combined computational-experimental prediction approach to identify and characterize small RNAs (sRNAs) in Pseudomonas aeruginosa PAO1. We defined the first pan-sRNome, including 1663 sRNAs across 484 P. aeruginosa strains, and classified our 9 newly discovered sRNAs as 3 core and 6 accessory elements within the regulatory network. Functional studies revealed distinct sRNA activities: PA0982.1 was found to be a direct regulator of the rhl quorum sensing system. PA1014.1, PA2734.1, and PA2736.2 enhanced pyocyanin production. PA1014.1 and PA2734.1 facilitated biofilm formation for surface attachment. PA2734.1 and PA2736.2 suppressed motility to regulate dispersal, collectively shaping virulence traits. Additionally, PA1270.1, PA1367.1, and PA3471.1 were associated with reduced interbacterial competitiveness and the downregulation of the Type VI secretion system. Evolutionary analysis across diverse bacterial taxa and archaea demonstrated selective conservation, exposing the evolutionary trajectory of a diverse group of regulatory molecules. Overall, this study not only expands the P. aeruginosa sRNA landscape but also provides a framework for understanding how sRNAs fine-tune virulence and evolutionary adaptation.
