Yuanming Huang

Background: The global prevalence of hyperuricemia (HUA) has increased worldwide, and probiotics are considered an adjunctive treatment with fewer side effects. However, the effective strains and underlying mechanisms are not well understood. Objective: This study aimed to investigate the role of Lacticaseibacillus paracasei SUB12 (SUB12) in alleviating HUA and elucidate its potential molecular mechanisms. Methods: In this study, a HUA mouse model was established using potassium oxonate and adenine to evaluate the uric acid-lowering effect of SUB12. High-throughput metabolomics and 16S rRNA sequencing were used to identify key metabolites and altered microbiota. Results: Oral administration of SUB12 significantly reduced serum UA level, hepatic xanthine oxidase (XOD) activity, and renal inflammation and altered uric acid transport-related proteins. Sequencing analysis suggested that SUB12 not only had the capacity of consuming succinate but also reduced the abundance of succinate-producing Prevotellamassilia. Succinate supplementation significantly promoted XOD activity through the succinate receptor 1 (SUCNR1)/hypoxia-inducible factor 1-alpha (HIF-1α) axis. Conclusions: Our findings reveal that SUB12 attenuates hyperuricemia by down-regulating succinate, which promotes XOD activity and uric acid production through the SUCNR1/HIF-1α/XOD axis.

Background: Douzhier, a traditional Chinese fermented food with a history spanning over 1000 years, harbors a complex community of beneficial microbiota. In this study, we isolated Lactococcus lactis subsp. cremoris (designated L. cremoris D2022), one of the dominant bacterial species in Douzhier, and evaluated its efficacy against influenza A virus (IAV) infection. Methods: A murine model of IAV infection was established using C57BL/6J mice. Following oral administration of L. cremoris D2022, treated and model control groups (IAV-infected model control group received phosphate-buffered saline (PBS)) were comparatively assessed through clinical outcomes (body weight dynamics and survival), pathological parameters (colon length, lung index, and lung histopathology), inflammatory cytokine profiling, multi-omics analyses (lung transcriptomics and cecal metabolomics), and adaptive immune responses. Results: Administration of L. cremoris D2022 markedly alleviated IAV-induced pathology compared with PBS-treated model controls, as evidenced by improved survival (30% vs. 0%, p = 0.006), reduced body weight loss, decreased lung index, and preservation of colon length. D2022 treatment accelerated viral clearance, accompanied by enhanced early interferon beta (IFN-β) production. This was followed by suppression of late-stage hyperinflammation, including reduced levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) at 7 dpi. Metabolomic analysis revealed increased levels of deaminotyrosine (DAT), short-chain fatty acids (SCFAs), and microbially conjugated bile acids (e.g., ursodeoxycholic acid (UDCA) and isoallolithocholic acid (isoalloLCA)). Furthermore, IAV-specific adaptive immune responses were significantly enhanced. Conclusions: L. cremoris D2022 protects mice against IAV infection, with enhanced early IFN-β responses, reduced late-stage inflammation, and associated changes in intestinal microbial metabolites. The causal roles of these metabolites remain to be established. These findings support further evaluation of D2022 as a probiotic candidate for adjunctive influenza prevention.

Klebsiella pneumoniae (KP) is an important opportunistic pathogen that can persist in the gastrointestinal tract and serve as a reservoir for subsequent infection. The increasing prevalence of multidrug-resistant KP highlights the need for non-antibiotic strategies to limit intestinal KP burden and associated host injury. Lactiplantibacillus plantarum GUANKE (L. plantarum GUANKE) is a candidate probiotic strain with reported effects on mucosal barrier protection and inflammatory regulation, but its role in intestinal KP challenge remains unclear. In this study, the effects of L. plantarum GUANKE and its metabolite phenyllactic acid (PLA) on KP growth, intestinal KP burden, and associated inflammatory injury were investigated using antibacterial assays in vitro, metabolomic analyses, an antibiotic-pretreated mouse model of intestinal KP challenge, and an influenza A virus (IAV)/KP intestinal co-exposure model. L. plantarum GUANKE and its culture-derived products inhibited KP growth in vitro. Metabolomic analysis identified PLA as a metabolite enriched in L. plantarum GUANKE fermentation supernatants, and exogenous PLA directly inhibited KP growth in a dose-dependent manner. In an antibiotic-pretreated mouse model of intestinal KP challenge, oral administration of L. plantarum GUANKE reduced intestinal KP burden and was associated with changes in gut microbiota composition, increased cecal PLA abundance, improved intestinal barrier-related parameters, and reduced inflammatory responses, while exogenous PLA partially reproduced these effects. IAV infection increased susceptibility to intestinal KP expansion, and oral L. plantarum GUANKE reduced KP burden in the IAV/KP intestinal co-exposure model. In mice challenged with multidrug-resistant KP strain NK04152, L. plantarum GUANKE and PLA reduce intestinal KP burden and associated tissue injury in mice, supporting their potential as candidate microbiota and metabolite strategies against intestinal KP challenge.

Plague, caused by Yersinia pestis, remains a significant public health concern, yet the determinants of many toxin-associated proteins encoded by this pathogen remain poorly understood. Here, we characterized two previously unexplored Rearrangement hotspot (Rhs) proteins, YPO3609 and YPO3615, using a combination of bioinformatic analyses, bacterial toxicity assays, DNA degradation assays, SOS reporter assays, and RT-qPCR analysis. The C-terminal domains of YPO3609 and YPO3615 confer nuclease toxicity, with YPO3609 containing a WHH motif of the HNH nuclease superfamily and YPO3615 harboring a restriction endonuclease-like aspartate dyad. Heterologous expression of these C-terminal toxin domains in Escherichia coli inhibited growth, caused DNA degradation, elicited SOS-related responses, and induced cellular filamentation. Co-expression experiments identified YPO3610 and YPO3616 as the cognate immunity proteins of YPO3609 and YPO3615, respectively, while site-directed mutagenesis further showed that H411 and D1442/D1447 contribute to the nuclease-associated activities of the two toxins. Homologs of both toxin domains were broadly distributed in Pseudomonadota, with the C-terminal domain of YPO3609 showing a wider distribution. These findings characterize two functional Rhs toxin–immunity modules encoded by Y. pestis, and provide new insights into Rhs-associated nuclease toxins and their related homologs.

Background: Gut microbiota dysbiosis is critically implicated in the pathogenesis of allergic airway inflammation (AAI) via the gut–lung axis. While Latilactobacillus curvatus is a promising probiotic candidate, its specific immunomodulatory mechanisms in respiratory diseases remain poorly understood. Objective: In this study, we investigated the protective effects and underlying mechanisms of L. curvatus IM01 in an ovalbumin (OVA)-induced murine AAI model using an integrated multi-omics approach. Results: Our results demonstrated that oral administration of L. curvatus IM01 significantly attenuated airway inflammation, suppressed Th2-type immune responses, and reduced serum IgE levels. Crucially, our multi-omics integration revealed a coherent gut–lung axis narrative driven by microbial and metabolic crosstalk. Specifically, 16S rRNA sequencing indicated that L. curvatus IM01 was closely linked to structural shifts in the gut microbial community, notably characterized by an enrichment trend for beneficial genera such as Odoribacter and Lactobacillus. This microbial restructuring was closely associated with a modulated cecal metabolic profile, as untargeted metabolomics exhibited a clear trend toward the restoration of key systemically active immunoregulatory metabolites, including indolelactic acid (ILA) and choline, which have been previously linked to the alleviation of AAI symptoms. Further linking this metabolic shift to respiratory immune tolerance, lung transcriptomic analysis showed that the treatment is strongly associated with the promotion of the differentiation of CD4⁺ T cells into Foxp3⁺ regulatory T cells (Tregs). Conclusions: Collectively, these findings suggest a novel potential pathway by which L. curvatus IM01 modulates the gut–lung axis through coordinated microbial and metabolic interventions, highlighting its potential as a therapeutic functional food ingredient for AAI.

Background/Objectives: To investigate the antagonistic effect of probiotic Lactiplantibacillus plantarum GUANKE against respiratory syncytial virus (RSV) and its underlying molecular mechanisms. Methods: in vitro cell models (A549 and HEp2 cells) and an in vivo mouse model (BALB/c mice) were employed. RT-qPCR, TCID50 assay, immunofluorescence, ELISA, Western blot, and histopathological analysis were used to investigate the effects of GUANKE on RSV replication, inflammatory responses, and the type I interferon pathway. Results: Oral administration of GUANKE effectively cleared RSV and alleviated RSV-induced pulmonary inflammatory responses. GUANKE inhibited viral replication. The GUANKE intervention group exhibited significantly reduced pathological damage to lung tissue and decreased the expression of inflammatory cytokines (IL-1β, IL-6, MCP-1, TNF-α). GUANKE augmented the early type I interferon response and activated the STING-TBK1-IRF3-IFN signaling pathway. Conclusions: GUANKE exerts anti-RSV effects by enhancing the early type I interferon response and activating the STING-TBK1-IRF3-IFN signaling pathway, thereby inhibiting RSV replication and alleviating pulmonary inflammatory responses. This suggests its potential value as an anti-RSV agent.

Lactiplantibacillus plantarum GUANKE (L. plantarum GUANKE) is a Gram-positive bacterium isolated from the feces of healthy volunteers. Whole-genome sequencing analysis (WGS) revealed that the genome of L. plantarum GUANKE consists of one chromosome and two plasmids, with the chromosome harbors 2955 CDS, 66 tRNAs, and 5 rRNAs. The genome is devoid of virulence factors and Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems. It contains three intact prophage regions and bacteriocin biosynthesis genes (plantaricins K, F, and E), as well as seventeen genomic islands lacking antibiotic resistance or pathogenicity determinants. Functional prediction outcomes identified that the genome of L. plantarum GUANKE is closely related to transcription, carbohydrate transport and metabolism, and amino acid transport and metabolism. Carbohydrate-active enzymes (CAZymes) analysis and GutSMASH analysis revealed that the genome of L. plantarum GUANKE contained 100 carbohydrate-active enzyme genes and two specialized metabolic gene clusters. Safety assessments confirmed that L. plantarum GUANKE neither exhibited β-hemolytic activity nor harbored detectable transferable drug resistance genes. The strain exhibited remarkable acid tolerance and bile salt resistance. Cellular adhesion assays demonstrated moderate binding capacity to Caco-2 intestinal epithelium (4.3 ± 0.007)%. In vitro analyses using lipopolysaccharide (LPS)-stimulated macrophage models demonstrated that L. plantarum GUANKE significantly suppressed the secretion of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β), exhibiting dose-dependent anti-inflammatory activity. In vivo experiments showed that L. plantarum GUANKE was involved in the regulation of the apical junction pathway and interferon pathway in colon tissue of normal mice.

Background/Objectives: Gut microbiota is essential for maintaining host immune homeostasis and has been confirmed to be closely related to some intestinal and extraintestinal diseases. Bacteroides, as the dominant bacterial genus in the human gut, has attracted great attention due to its excellent metabolic activity, but there are few studies on Bacteroides dorei species. In our previous study, a gut commensal strain, Bacteroides dorei RX2020 (B. dorei), was isolated from healthy human feces and exhibited superior flavonoid metabolic activity, prompting further analysis of its uncharacterized genomic features, probiotic potential, safety, and immunomodulatory activity. Results: The results showed that B. dorei exhibited intrinsic probiotic functionalities with preserved genomic and phenotypic stability, demonstrated safety profiles in murine models through in vivo assessments, and conferred antagonistic activity against enteric foodborne pathogens via competitive exclusion. The strain also demonstrated abundant metabolic activity and was involved in the metabolism of tryptophan and bile acids (BAs). Moreover, B. dorei can promote the production of IFNβ by dendritic cells (DCs) to inhibit the replication of influenza virus in epithelial cells, which may be achieved by regulating host metabolism. Conclusions: This study reveals the potential of B. dorei as next-generation probiotics (NGPs), contributing to a broader understanding and application of these novel probiotics in health and disease management.

Influenza, a severe respiratory disease caused by the influenza virus, has long been a prominent threat to human health. An increasing number of studies have demonstrated that oral administration with probiotics may increase the immune response to lung infection via the gut-lung axis leading to the alleviation of the pulmonary disease. In this study, we evaluated the effects of oral administration of Pediococcus pentosaceus MIANGUAN2 (MIANGUAN2) on influenza infection in a mouse model. Our results showed that oral administration of MIANGUAN2 significantly improved weight loss, lung index, and lung pathology, and decreased lung viral load of influenza-infected mice. Additionally, MIANGUAN2-treated mice showed significantly lower levels of TNF-α, IL-1β, IFN-γ, and IL-12p70 and higher production of IL-4 in the lung. In accordance with this, the transcriptome analysis of the lung indicated that MIANGUAN2-treated mice had reduced expression of inflammation markers, such as TNF, apoptosis, and the NF-Kappa B pathway. Furthermore, the administration of MIANGUAN2 restored the SCFAs profiles through regulating the gut microbiota. SCFA-producing bacteria, such as p_Firmicutes, f_Lachnospiraceae, and f_Ruminococcaceae, were enriched in the MIANGUAN2-treated group compared with PBS-treated group. Consistently, the concentrations of SCFAs in the MIANGUAN2 group were significantly higher than those in the PBS-treated group. In addition, the concentrations of SCFAs were positively correlated with SCFA-producing bacteria, such as Ruminococcus, while being negatively correlated with the virial titers and proinflammatory cytokines. In conclusion, this animal study suggests that Pediococcus pentosaceus MIANGUAN2 may alleviate the influenza infection by altering the gut microbiota composition and increasing the levels of gut microbiota-derived SCFAs.

Slow transit constipation (STC) is a prevalent gastrointestinal condition with slow transit, and some probiotics can effectively relieve constipation, but the exact mechanisms have not been fully understood. In this study, we evaluate the impact of Lactiplantibacillus plantarum GUANKE (GUANKE) on diphenoxylate-induced slow transit constipation and speculate on the underlying mechanisms in a mouse model. Administration of L. plantarum GUANKE alleviated constipation indexes, including defecation time, fecal output and water content, and gastrointestinal transit ratio. In addition, GUANKE restored the protein expression of constipation-related intestinal factors (aquaporins (AQPs) and interstitial Cajal cells (ICCs)) in colon tissues measured using immunofluorescence staining; regulated the neurotransmitters and hormones, such as increased levels of 5-hydroxytryptamine, substance P, and motilin; and decreased levels of vasoactive intestinal peptide and nitric oxide in serum, as measured by an ELISA. 16S rRNA and correlation analysis of feces indicated that GUANKE administration effectively reduced constipation-induced Prevotella enrichment and suggested a potential contribution of Prevotella to diphenoxylate-induced STC in mice. GUANKE had no effect on short-chain fatty acids (SCFAs) in cecum content. This study revealed that GUANKE may alleviate constipation in mice through regulating intestinal neurotransmitter and hormone release and altering specific bacterial taxa, rather than by affecting SCFAs and the diversity of microbiota in the gut. Further research is needed to confirm if the findings observed in this study will be consistent in other animal studies or clinical trials.