Distinct characteristics of the gut virome in patients with osteoarthritis and gouty arthritis.

BACKGROUND/PURPOSE(S): The gut microbiota and its metabolites play crucial roles in pathogenesis of arthritis, highlighting gut microbiota as a promising avenue for modulating autoimmunity. However, the characterization of the gut virome in arthritis patients, including osteoarthritis (OA) and gouty arthritis (GA), requires further investigation. METHODS: We employed virus-like particle (VLP)-based metagenomic sequencing to analyze gut viral community in 20 OA patients, 26 GA patients, and 31 healthy controls, encompassing a total of 77 fecal samples. RESULTS: Our analysis generated 6819 vOTUs, with a considerable proportion of viral genomes differing from existing catalogs. The gut virome in OA and GA patients differed significantly from healthy controls, showing variations in diversity and viral family abundances. We identified 157 OA-associated and 94 GA-associated vOTUs, achieving high accuracy in patient-control discrimination with random forest models. OA-associated viruses were predicted to infect pro-inflammatory bacteria or bacteria associated with immunoglobulin A production, while GA-associated viruses were linked to Bacteroidaceae or Lachnospiraceae phages. Furthermore, several viral functional orthologs displayed significant differences in frequency between OA-enriched and GA-enriched vOTUs, suggesting potential functional roles of these viruses. Additionally, we trained classification models based on gut viral signatures to effectively discriminate OA or GA patients from healthy controls, yielding AUC values up to 0.97, indicating the clinical utility of the gut virome in diagnosing OA or GA. CONCLUSION: Our study highlights distinctive alterations in viral diversity and taxonomy within gut virome of OA and GA patients, offering insights into arthritis etiology and potential treatment and prevention strategies.

Characterizations of gut bacteriome, mycobiome, and virome of healthy individuals living in sea-level and high-altitude areas.

BACKGROUND: The contribution of gut microbiota to human high-altitude adaptation remains inadequately understood. METHODS: Here a comparative analysis of gut microbiota was conducted between healthy individuals living at sea level and high altitude using deep whole-metagenome shotgun sequencing, to investigate the adaptive mechanisms of gut microbiota in plateau inhabitants. RESULTS: The results showed the gut bacteriomes in high-altitude individuals exhibited greater within-sample diversity and significant alterations in both bacterial compositional and functional profiles when compared to those of sea-level individuals, indicating the potential selection of unique bacteria associated with high-altitude environments. The strain-level investigation revealed enrichment of Collinsella aerofaciens and Akkermansia muciniphila in high-altitude populations. The characteristics of gut virome and gut mycobiome were also investigated. Compared to sea-level subjects, high-altitude subjects exhibited a greater diversity in their gut virome, with an increased number of viral operational taxonomic units (vOTUs) and unique annotated genes. Finally, correlation analyses revealed 819 significant correlations between 42 bacterial species and 375 vOTUs, while no significant correlations were observed between bacteria and fungi or between fungi and viruses. CONCLUSION: The findings have significantly contributed to an enhanced comprehension of the mechanisms underlying the high-altitude geographic adaptation of the human gut microbiota.

Characterizations of the multi-kingdom gut microbiota in Chinese patients with gouty arthritis.

OBJECTIVE: The gut microbial composition has been linked to metabolic and autoimmune diseases, including arthritis. However, there is a dearth of knowledge on the gut bacteriome, mycobiome, and virome in patients with gouty arthritis (GA). METHODS: We conducted a comprehensive analysis of the multi-kingdom gut microbiome of 26 GA patients and 28 healthy controls, using whole-metagenome shotgun sequencing of their stool samples. RESULTS: Profound alterations were observed in the gut bacteriome, mycobiome, and virome of GA patients. We identified 1,117 differentially abundant bacterial species, 23 fungal species, and 4,115 viral operational taxonomic units (vOTUs). GA-enriched bacteria included Escherichia coli_D GENOME144544, Bifidobacterium infantis GENOME095938, Blautia_A wexlerae GENOME096067, and Klebsiella pneumoniae GENOME147598, while control-enriched bacteria comprised Faecalibacterium prausnitzii_G GENOME147678, Agathobacter rectalis GENOME143712, and Bacteroides_A plebeius_A GENOME239725. GA-enriched fungi included opportunistic pathogens like Cryptococcus neoformans GCA_011057565, Candida parapsilosis GCA_000182765, and Malassezia spp., while control-enriched fungi featured several Hortaea werneckii subclades and Aspergillus fumigatus GCA_000002655. GA-enriched vOTUs mainly attributed to Siphoviridae, Myoviridae, Podoviridae, and Microviridae, whereas control-enriched vOTUs spanned 13 families, including Siphoviridae, Myoviridae, Podoviridae, Quimbyviridae, Phycodnaviridae, and crAss-like. A co-abundance network revealed intricate interactions among these multi-kingdom signatures, signifying their collective influence on the disease. Furthermore, these microbial signatures demonstrated the potential to effectively discriminate between patients and controls, highlighting their diagnostic utility. CONCLUSIONS: This study yields crucial insights into the characteristics of the GA microbiota that may inform future mechanistic and therapeutic investigations.

Taurine ameliorates axonal damage in sciatic nerve of diabetic rats and high glucose exposed DRG neuron by PI3K/Akt/mTOR-dependent pathway.

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes and axonopathy is its main pathological feature. Previous studies suggested an advantage of taurine against diabetes. However, there are few reports which study the effect of taurine against axonopathy. In this study, we confirmed that taurine significantly decreased blood glucose level, mitigated insulin resistance and improved dysfunctional nerve conduction in diabetic rats. Taurine corrected damaged axonal morphology of sciatic nerve in diabetic rats and induced axon outgrowth of Dorsal root ganglion (DRG) neurons exposed to high glucose. Taurine up-regulated phosphorylation levels of PI3K, Akt, and mTOR in sciatic nerve of diabetic rats and DRG neurons exposed to high glucose. However, Akt and mTOR inhibitors (MK-2206 and Rapamycin) blocked the effect of taurine on improving axonal damage. These results indicate that taurine ameliorates axonal damage in sciatic nerve of diabetic rats by activating PI3K/Akt/mTOR signal pathway. Our findings provide taurine as a potential candidate for axonopathy and a new evidence for elucidating protective mechanism of taurine on DPN.

Inducible knockdown of Mycobacterium smegmatis MSMEG_2975 (glyoxalase II) affected bacterial growth, antibiotic susceptibility, biofilm, and transcriptome.

Tuberculosis (TB) causes millions of deaths each year across the globe. Multiple drug-resistant (MDR) and extensively drug-resistant (XDR) mycobacterial strains have made the treatment extremely difficult. To overcome this hurdle, the development of new drug targets and an effective treatment strategy are desperately needed. This can be achieved by deciphering the role of essential genes and enzymes which are involved in cell survival. One such enzyme is glyoxalase II. The glyoxalase system (glyoxalase I and glyoxalase II) has a pivotal role in cellular survival and detoxification by converting methylglyoxal (MG) into lactate. Otherwise, the increased concentration of MG then modifies DNA, proteins, and lipids, resulting in abnormalities and cell death. Interestingly, the function and physiological role of glyoxalase II have remained undetermined in mycobacteria. In this study, the functional activity of MSMEG_2975 (putative glyoxalase II) after heterologous cloning and expression was determined. And the knockdown strain Mycobacterium smegmatis KD for MSMEG_2975 was constructed with tetracycline-inducible vector pMIND. The inducible knockdown of MSMEG_2975 affected bacterial growth, biofilm formation, transcriptome, and enhanced the susceptibility to antibiotics. This work represents mycobacterial glyoxalase II as a potential drug target against mycobacterial pathogens and indicates the crucial regulatory role of glyoxalase II in mycobacteria.

Limosilactobacillus reuteri HCS02-001 Attenuates Hyperuricemia through Gut Microbiota-Dependent Regulation of Uric Acid Biosynthesis and Excretion.

Hyperuricemia is a prevalent metabolic disorder that arises from abnormal purine metabolism and reduced excretion of uric acid (UA). The gut microbiota plays a significant role in the biosynthesis and excretion of UA. Probiotics capable of purine degradation possess the potential to prevent hyperuricemia. Our study aimed to screen probiotics in areas with abundant dairy products and longevity populations in China, which could attenuate the level of UA and explore the underlying mechanism. In this study, twenty-three lactic acid bacteria isolated from healthy Chinese infant feces and traditional fermented foods such as hurood and lump milk were evaluated for the ability to tolerance acid, bile, artificial gastric juice, and artificial intestinal juice to determine the potential of the candidate strains as probiotics. Eight strains were identified as possessing superior tolerance to simulated intestinal conditions and were further analyzed by high-performance liquid chromatography (HPLC), revealing that Limosilactobacillus reuteri HCS02-001 (Lact-1) and Lacticaseibacillus paracasei HCS17-040 (Lact-2) possess the most potent ability to degrade purine nucleosides. The effect of Lact-1 and Lact-2 on hyperuricemia was evaluated by intervening with them in the potassium oxonate and adenine-induced hyperuricemia Balb/c mice model in vivo. Our results showed that the level of serum UA in hyperuricemic mice can be efficiently reduced via the oral administration of Lact-1 (p < 0.05). It significantly inhibited the levels of liver inflammatory cytokines and hepatic xanthine oxidase through a TLR4/MyD88/NF-κB pathway across the gut-liver axis. Furthermore, UA transporters ABCG2 and SLC2A9 were substantially upregulated by the intervention of this probiotic. Fecal ATP levels were significantly induced, while fecal xanthine dehydrogenase and allantoinase levels were increased following probiotics. RNA sequencing of HT-29 cells line treated with Lact-1 and its metabolites demonstrated significant regulation of pathways related to hyperuricemia. In summary, these findings demonstrate that Limosilactobacillus reuteri HCS02-001 possesses a capacity to ameliorate hyperuricemia by inhibiting UA biosynthesis via enhancing gastrointestinal barrier functions and promoting UA removal through the upregulation of urate transporters, thereby providing a basis for the probiotic formulation by targeting the gut microbiota.

Saccharomyces boulardii (CNCM I-745) alleviates collagen-induced arthritis by partially maintaining intestinal mucosal integrity through TLR2/MYD88/NF-κB pathway inhibition.

BACKGROUND: Rheumatoid arthritis, a condition characterized by inflammation, has a substantial influence on both the worldwide economy and public health. Prior studies indicate that probiotics have the potential to enhance the composition of gut microbiota in instances of intestinal dysbiosis resulting from different disorders and contribute to the regulation of inflammation. The objective of this study is to investigate the impact of Saccharomyces boulardii on the gut microbiome in arthritis and its implications on inflammation. METHODS: The study utilized the Collagen Induced Arthritis (CIA) Sprague-Dawley (SD) rat model. After administering Saccharomyces boulardii (150 mg/kg/day) six days a week and Methotrexate (MTX) (0.2 mg/week) treatment for eight weeks, microbial DNA from the feces was sequenced using 16S rRNA. The evaluation of histopathology, bone loss, and cartilage degradation was conducted using histology, immunohistology assays, and micro-computed tomography (µCT) examinations. The enzyme-linked immunosorbent assay (ELISA) was used to analyze proinflammatory cytokines, while the western blot technique was applied to detect protein in the gut and in cell lines. The quantification of gene expression in gut,joint and cell lines was performed using real-time polymerase chain reaction. The cell lines were activated and then treated with the culture supernatant of S. boulardii for an in vitro investigation. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test was utilized to assess cell proliferationand viability. Cellular motility was measured in a wound healing experiment, whereas apoptotic proteins were analyzed using Western blotting. RESULTS: S. boulardii has been found to enhance bone and joint integrity, modulate gut microbiota, and mitigate proinflammatory cytokine levels in rats with arthritis. It decreases the permeability of the intestines and promotes the production of gut tight-junction proteins. The administration of S. boulardii inhibits the proliferation of T-helper-17 (Th17) and Type 3 innate lymphoid cells (ILC3). Additionally, it elicits apoptosis in MH7A cell lines and hinders their migratory activity. CONCLUSION: This study provides valuable insights into the therapeutic potential of S. boulardii for treating and preventing arthritis in rats with collagen-induced arthritis by modulating gut microbiota and inflammation.

Mycobacterium tuberculosis PE_PGRS38 Enhances Intracellular Survival of Mycobacteria by Inhibiting TLR4/NF-κB-Dependent Inflammation and Apoptosis of the Host.

Mycobacterium tuberculosis (Mtb) ranks as the most lethal human pathogen, able to fend off repeated attacks by the immune system or medications. PE_PGRS proteins are hallmarks of the pathogenicity of Mtb and contribute to its antigenic diversity, virulence, and persistence during infection. M. smegmatis is a nonpathogenic mycobacterium that naturally lacks PE_PGRS and is used as a model to express Mtb proteins. PE_PGRS has the capability to evade host immune responses and enhance the intracellular survival of M. smegmatis. Despite the intense investigations into PE_PGRS proteins, their role in tuberculosis remains elusive. We engineered the recombinant M. smegmatis strain Ms-PE_PGRS38. The result shows that PE_PGRS38 is expressed in the cell wall of M. smegmatis. PE_PGRS38 contributes to biofilm formation, confers permeability to the cell wall, and shows variable responses to exogenous stresses. PE_PGRS38 downregulated TLR4/NF-κB signaling in RAW264.7 macrophages and lung tissues of infected mice. In addition, PE_PGRS38 decreased NLRP3-dependent IL-1ß release and limited pathogen-mediated inflammasome activity during infection. Moreover, PE_PGRS38 inhibited the apoptosis of RAW264.7 cells by downregulating the expression of apoptotic markers including Bax, cytochrome c, caspase-3, and caspase-9. In a nutshell, our findings demonstrate that PE_PGRS38 is a virulence factor for Mtb that enables recombinant M. smegmatis to survive by resisting and evading the host's immune responses during infection.

A population-scale analysis of 36 gut microbiome studies reveals universal species signatures for common diseases.

The gut microbiome has been implicated in various human diseases, though findings across studies have shown considerable variability. In this study, we reanalyzed 6314 publicly available fecal metagenomes from 36 case-control studies on different diseases to investigate microbial diversity and disease-shared signatures. Using a unified analysis pipeline, we observed reduced microbial diversity in many diseases, while some exhibited increased diversity. Significant alterations in microbial communities were detected across most diseases. A meta-analysis identified 277 disease-associated gut species, including numerous opportunistic pathogens enriched in patients and a depletion of beneficial microbes. A random forest classifier based on these signatures achieved high accuracy in distinguishing diseased individuals from controls (AUC = 0.776) and high-risk patients from controls (AUC = 0.825), and it also performed well in external cohorts. These results offer insights into the gut microbiome's role in common diseases in the Chinese population and will guide personalized disease management strategies.

Mycobacterium tuberculosis Rv1324 Protein Contributes to Mycobacterial Persistence and Causes Pathological Lung Injury in Mice by Inducing Ferroptosis.

Mycobacterium tuberculosis (Mtb) is the pathogenic agent of tuberculosis (TB). Intracellular survival plays a central role in the pathogenesis of Mtb, a process that depends on an array of virulence factors for Mtb to colonize and proliferate within a host. Reactive nitrogen and oxygen species (RNS and ROS) are among the most effective antimycobacterial molecules generated by the host during infection. However, Mtb has evolved a number of proteins and enzymes to detoxify ROS and RNS. Secretory protein Rv1324, as a possible thioredoxin, might also have oxidoreductase activity against ROS and RNS during Mtb infection, and it is a potential virulence factor of Mtb. In this study, we investigated the biochemical properties of Mtb Rv1324 and its role in mycobacterial survival and virulence. The results showed that the Rv1324 protein had antioxidant activity and increased the survival of M. smegmatis that was exposed to ROS and RNS. In addition, Rv1324 enhanced the colonization ability of M. smegmatis in the lungs of mice. Further, mice infected with M. smegmatis harboring Rv1324 exhibited pathological injury and inflammation in the lung, which was mediated by ferroptosis. In summary, this study advances our understanding of the mechanisms of mycobacterial survival and pathogenesis, and it reveals a novel target for TB treatment. IMPORTANCE The intracellular survival of M. tuberculosis (Mtb) plays a crucial role in its pathogenesis, which depends on various Mtb oxidoreductases that are resistant to reactive oxygen and nitrogen species (ROS and RNS) that are generated by the host during Mtb infection. Secretory protein Rv1324 is a potential virulence factor of Mtb and is a possible thioredoxin that has oxidoreductase activity against ROS and RNS during Mtb infection. We investigated the biochemical properties of Mtb Rv1324 and its role in mycobacterial survival and virulence. It was confirmed that the Rv1324 protein had antioxidant activity and an increased mycobacterial resistance to ROS and RNS. In addition, Rv1324 enhanced mycobacterial persistence and induced pathological injury and inflammation in the lungs of mice by activating ferroptosis. This study advances our understanding of the mechanisms of mycobacterial survival and pathogenesis, and it reveals a novel target for TB treatment.