Inflammatory bowel disease (IBD) presents a range of extraintestinal manifestations, notably including oral cavity involvement. The mechanisms underlying oral-gut crosstalk in IBD are not fully understood. Exosomes, found in various body fluids such as saliva, play an unclear role in IBD that requires further exploration. In the dextran sulfate sodium (DSS) mouse model, salivary exosomes from patients with active IBD (active IBD-Sexos) exacerbated colitis, while those from IBD patients in remission (remission IBD-Sexos) did not. Possible reasons may include the regulation of macrophage polarization, disruption of intestinal epithelial function, and alteration of the intestinal flora. During co-culture with active IBD-Sexos, THP-1 cells exhibited inflammatory responses, while Caco-2 cells showed reduced tight junction protein expression. Additionally, 35 differentially expressed miRNAs were identified in active IBD-Sexos. In brief, our findings substantiate an intriguing phenomenon whereby active IBD-Sexos exacerbate colitis by bridging the oral cavity and intestine.

The human oral microbiome has been associated with multiple inflammatory conditions including inflammatory bowel disease (IBD). Identifying functional changes in oral microbiome by metaproteomics helps understanding the factors driving dysbiosis related to intestinal diseases. However, enriching bacterial cells from oral samples (such as saliva and mouth rinse) rich in host proteins is challenging. Here, we present an Optimized Salivary MetaProteomic sample analysis workflow (OSaMPle) to enrich salivary bacteria and reduce host-derived interferences for in-depth analysis of the oral metaproteome. Compared to a conventional approach, OSaMPle improved the identification of bacterial peptides and proteins by 3.2 folds and 1.7 folds, respectively. Furthermore, applying OSaMPle to analyze mouth rinse samples from IBD patients revealed significant alterations in bacterial protein expressions under disease conditions. Specifically, proteins involved in the fatty acid elongation pathway in Peptostreptococcus were significantly less abundant in IBD patients, whereas proteins associated with the TCA cycle in Neisseria were significantly more abundant. The OSaMPle workflow is capable of processing small-volume oral samples and adaptable to high-throughput automation. It holds promise as a strategy for investigating the functional responses of oral microbiomes under disease conditions and identifying disease-associated microbes with their proteins, providing critical insights for detecting disease-related biomarkers within the oral microbiome.

Background and Aims: Crohn’s disease (CD) is a chronic inflammatory bowel disease (IBD) with a globally increasing prevalence, partially driven by alterations in gut microbiota. Although biological therapy is the first-line treatment for CD, a significant proportion of patients experience a primary non-response or secondary loss of response over time. This study aimed to explore the differences in gut microbiota among CD patients with divergent long-term responses to biological therapy, focusing on a long disease course. Methods: Sixteen CD patients who applied the biological agents for a while were enrolled in this study and were followed for one year, during which fecal specimens were collected monthly. Metagenomic analysis was used to determine the microbiota profiles in fecal samples. The response to biological therapy was evaluated both endoscopically and clinically. Patients were categorized into three groups based on their response: R (long-term remission), mA (mild active), and R2A group (remission to active). The differences in the gut microbiota among the groups were analyzed. Results: Significant differences in fecal bacterial composition were observed between the groups. The R2A group exhibited a notable decline in gut microbial diversity compared to the other two groups (p < 0.05). Patients in the R group had higher abundances of Akkermansia muciniphila, Bifidobacterium adolescentis, and Megasphaera elsdenii. In contrast, Veillonella parvula, Veillonella atypica, and Klebsiella pneumoniae were higher in the R2A group. Conclusions: Gut microbial diversity and specific bacterial significantly differed among groups, reflecting distinct characteristics between responders and non-responders.

Inflammatory bowel disease (IBD), a chronic inflammatory disorder with relapsing/remitting characteristics, lacks reliable non-invasive biomarkers for accurate diagnosis and longitudinal monitoring. This study explored salivary exosomal miRNAs as potential biomarkers to address this unmet clinical need. Using discovery (24 IBD patients [11 active, 13 remission] and 6 healthy controls [HCs]) and validation cohorts (102 IBD patients [53 active, 49 remission] and 18 HCs), we analyzed miRNA profiles via reverse transcription quantitative PCR (RT-qPCR). Receiver operating characteristic (ROC) curves evaluated diagnostic performance, with area under the curve (AUC) quantifying discriminatory capacity. Initial screening revealed 23 miRNAs significantly upregulated in IBD salivary exosomes. An 8-miRNA signature distinguished IBD patients from HCs in validation analyses, with five miRNAs (hsa-miR-1246, hsa-miR-142-3p, hsa-miR-16-5p, hsa-miR-301a-3p, and hsa-miR-4516) showing strong correlations with disease activity. The combination of hsa-miR-16-5p and hsa-miR-4516 achieved robust discrimination (AUC = 0.925 for IBD vs. HCs; AUC = 0.82 for active disease vs. remission). A composite model integrating all five miRNAs demonstrated superior performance (AUC = 1.00 for IBD/HC differentiation; AUC = 0.86 for disease activity assessment). These findings reveal dynamic associations between salivary exosomal miRNA signatures and IBD progression, underscoring their utility as non-invasive diagnostic tools. This approach enables serial sampling, enhances patient compliance, and provides actionable insights for personalized disease management, establishing salivary exosomal miRNAs as promising candidates for clinical translation in IBD care.

Inflammatory bowel disease (IBD), comprising Crohn’s disease (CD) and ulcerative colitis (UC), is affecting a growing global population. Unlike UC, which is characterized by inflammation confined to the intestinal mucosa and submucosa, CD involves transmural inflammation of the intestine. Although the lymphatic system is believed to play a role in the pathogenesis of CD, its exact contribution remains poorly understood. Mesenteric lymphatics (MLs), which drain interstitial fluid and immune cells into mesenteric lymph nodes, have been implicated in this process. In the present study, we aimed to investigate the role of ML immune cells in TNBS-induced colitis in rats. Flow cytometry analysis revealed an increased ratio of B cells and altered B cell function in the MLs of colitis rats compared to controls. The adoptive transfer of mesenteric lymphatic B (MLB) cells isolated from colitis rats to recipient rats exacerbated colitis and was associated with the enhanced migration of MLB cells to the gut. RNA sequencing analysis demonstrated a significant upregulation of genes associated with inflammation and immune responses in MLB cells from colitis rats, particularly key molecules involved in T cell activation, such as cluster of differentiation 27 (Cd27) and cluster of differentiation 40 (Cd40), and the chemotactic receptor C-C motif chemokine receptor 8 (Ccr8), which mediates B cell migration in response to T cells. Mechanistically, MLB cells from colitis rats were recruited to the colon by intra-intestinal T cells through the Ccr8-C-C motif chemokine ligand 1 (Ccl1) axis, where they subsequently exacerbated inflammatory responses via enhanced differentiation. These observations indicate that the migration of MLB cells to the gut exacerbates TNBS-induced colitis in rats by modulating intestinal T cells.