Background: Rheumatoid arthritis (RA) is a chronic inflammatory disabling autoimmune disorder. Little is known regarding the association between the gut microbiome and etiopathogenesis of RA. We aimed to dissect the differences in gut microbiomes associated with RA in comparison to healthy individuals and, in addition, to identify the shifts in the bacterial community in association with disease activity; Methods: In order to identify compositional shifts in gut microbiomes of RA patients, V3-V4 hypervariable regions of 16S rRNA were sequenced using Illumina MiSeq. In total, sixty stool samples were collected from 45 patients with RA besides 15 matched healthy subjects; Results: Notably, RA microbiomes were significantly associated with diverse bacterial communities compared with healthy individuals. Likewise, a direct association between bacterial diversity and disease activity was detected in RA patients (Kruskal Wallis; p = 0.00047). In general, genus-level analysis revealed a positive coexistence between RA and Megasphaera, Adlercreutzia, Ruminococcus, Bacteroides, Collinsella, and Acidaminococcus. Furthermore, Spearman correlation analysis significantly stratified the most dominant genera into distinct clusters that were mainly based on disease activity (r ≥ 0.6; p ≤ 0.05). The predictive metabolic profile of bacterial communities associated with RA could support the potential impact of gut microbiomes in either the development or recovery of RA; Conclusions: The overall shifts in bacterial composition at different disease statuses could confirm the cross-linking of certain genera either to causation or progression of RA.

Background: Colorectal cancer (CRC) is a public health concern and the second most common disease worldwide. This is due to genetic coding and is influenced by environmental aspects, in which the gut microbiota plays a significant role. The purpose of this study was to compare the microbiota makeup of CRC patients with that of healthy control and to identify upregulated and downregulated proteins and metabolites in CRC patients. Using a next-generation sequencing approach, fecal samples of five females (4 CRC patients and one healthy control) were analyzed by BGI DNBSEQ-T7, Hong Kong, China. Furthermore, proteomics and metabolomics analysis were performed using LC-MS/MS technique. Results: Dysbiosis of gut microbiota has been observed in patients with CRC, with an increase in microbiota diversity at all taxonomic levels relative to healthy control. Where, at the functional level the bacterial species participate in many different pathways among them de novo nucleotide synthesis and amino acids pathways were aberrantly upregulated in CRC patients. Proteomics and metabolomics profiles of CRC patients showed different proteins and metabolites, a total of 360 and 158 proteins and metabolites, respectively were highly expressed compared to healthy control with fold change ≥ 1.2. Among the highly expressed proteins were transketolase, sushi domain-containing protein, sulfide quinone oxidoreductase protein, AAA family ATPase protein, carbonic anhydrase, IgG Fc-binding protein, nucleoside diphosphate kinase protein, arylsulfatase, alkaline phosphatase protein, phosphoglycerate kinase, protein kinase domain-containing protein, non-specific serine/threonine protein kinase, Acyl-CoA synthetase and EF-hand domain-containing protein. Some of the differential metabolites, Taurine, Taurocholic acid, 7-ketodeoxycholic acid, Glycochenodeoxycholic acid, Glycocholic acid, and Taurochenodeoxycholic acid that belong to bile acids metabolites. Conclusions: Some bacterial species, proteins, and metabolites could be used as diagnostic biomarkers for CRC. Our study paves an insight into using multi-omics technology to address the relationship between gut microbiota and CRC.

Background: Helicobacter pylori (H. pylori) is significantly linked to various diseases that seriously impact human health, such as gastric ulcers, chronic gastritis and gastric adenocarcinoma. Methods: The compositional shifts in bacterial communities of the orointestinal axis were surveyed pre/post-eradication of H. pylori. In total, 60 samples, including stool and salivary specimens, were collected from 15 H. pylori-positive individuals (HPP) before beginning and 2 months after receiving the eradication therapy. The V3-V4 regions of the 16S rRNA gene were sequenced using MiSeq. Results: Overall, oral microbiomes were collectively more diverse than the gut microbiomes (Kruskal–Wallis; p = 3.69 × 10⁻⁵). Notably, the eradication of H. pylori was associated with a significant reduction in the bacterial diversity along the orointestinal axis (Wilcoxon rank sum test; p = 6.38 × 10⁻³). Interestingly, the oral microbiome of HPP showed a positive correlation between Proteobacteria and Fusobacteria, in addition to a significant predominance of Streptococcus, in addition to Eubacterium_eligens, Haemophilus, Ruminococcaceae, Actinomyces and Staphylococcus. On the other hand, Fusobacterium, Veillonella, Catenibacterium, Neisseria and Prevotella were significantly enriched upon eradication of H. pylori. Generally, Bacteroidetes and Fusobacteria positively coexisted during H. pylori infection along the orointestinal axis (r = 0.67; p = 0.0006). The eradication of H. pylori was positively linked to two distinctive orotypes (O3 and O4). Orotype O4 was characterized by a robust abundance of Veillonella and Fusobacteria. The gut microbiomes during H. pylori infection showed a remarkable predominance of Clostridium_sensu_stricto_1 and Escherichia_Shigella. Likewise, Bifidobacterium and Faecalibacterium were significantly enriched upon eradication of H. pylori. Conclusions: Finally, the impact of eradication therapy clearly existed on the representation of certain genera, especially in the oral microbiome, which requires particular concern in order to counteract and limit their subsequent threats.

Background: Rotavirus gastroenteritis (RVGE) remains a leading cause of severe infant diarrhea worldwide, with growing evidence supporting the role of the gut microbiome in modulating the disease. However, the interplay between early-life demographic factors, the gut microbiome, and their combined impact on RVGE clinical severity remains inadequately characterized, particularly in specific geographic populations. Aim: We aimed to investigate how demographic determinants shape gut microbiome composition and function in RVGE and how these features relate to clinical severity. Methods: In our comprehensive case–control study of 165 infants (120 RVGE cases and 45 healthy controls, aged 0–12 months), we utilized 16S rRNA sequencing combined with advanced statistical modeling and machine learning to investigate how demographic factors influence microbiome composition and clinical outcomes. Results: RVGE cases exhibited significantly reduced bacterial diversity (Kruskal–Wallis, Static = 14.85, p < 0.001) and distinct patterns, with community structure most strongly associated with dehydration severity (PERMANOVA; R² = 0.15, p < 0.001). Substantial taxonomic alterations were identified characterized by depletion of beneficial commensals including Akkermansia (LDA score = 3.8, p < 0.001), Faecalibacterium (Random Forest AUC = 0.82, p < 0.001), and Bifidobacterium (r = −0.42 with breastfeeding, p < 0.001), alongside enrichment of inflammation-associated taxa such as Escherichia-Shigella (WBC; r = 0.49, p < 0.001, and CRP; r = 0.56, p < 0.001), Streptococcus (LDA score = 4.2, p < 0.001), and Staphylococcus. Proteobacteria was the top potential biomarker of severe outcomes (Random Forest AUC = 0.85), with abundance positively correlated with systemic inflammation (CRP: r = 0.51, p = 0.003). Functional predictions revealed increased lipopolysaccharide biosynthesis (ko00540) and reduced butanoate metabolism (ko00650, p < 0.001) in severe disease. Importantly, demographic factors significantly modulated clinical outcomes: cesarean-delivered, formula-fed infants presented the most dysbiotic profiles and experienced 3.2-fold longer hospitalization (95% CI: 1.8–5.6, p < 0.001) than vaginally delivered, breastfed infants did. Conclusions: Collectively, these findings demonstrate that early-life demographic factors potentially shape the gut microbiome composition and function, may influence RVGE severity and recovery trajectories, thus providing candidate biomarkers for risk stratification and identifying targets for microbiota-based interventions.