Abnormal metabolism of gut microbiota reveals the possible molecular mechanism of nephropathy induced by hyperuricemia

Folic Acid Protects against Hyperuricemia in C57BL/6J Mice via Ameliorating Gut-Kidney Axis Dysfunction

Emerging lines of research evidence point to a vital role of gut-kidney axis in the development of hyperuricemia (HUA), which has been identified as an increasing burden worldwide due to the high prevalence. The involved crosstalk which links the metabolic and immune-related pathways is mainly responsible for maintaining the axial homeostasis of uric acid (UA) metabolism. Nowadays, the urate-lowering drugs only aim to treat acute gouty arthritis as a result of their controversial clinical application in HUA. In this study, we established the HUA model of C57BL/6J mice to evaluate the effectiveness of folic acid on UA metabolism and further explored the underlying mechanisms. Folic acid attenuated the kidney tissue injury and excretion dysfunction, as well as the typical fibrosis in HUA mice. Molecular docking results also revealed the structure-activity relationship of the folic acid metabolic unit and the UA transporters GLUT9 and URAT1, implying the potential interaction. Also, folic acid alleviated HUA-induced Th17/Treg imbalance and intestinal tissue damage and inhibited the active state of the TLR4/NF-κB signaling pathway, which is closely associated with the circulating LPS level caused by the impaired intestinal permeability. Furthermore, the changes of intestinal microecology induced by HUA were restored by folic acid, including the alteration in the structure and species composition of the gut microbiome community, and metabolite short-chain fatty acids. Collectively, this study revealed that folic acid intervention exerted improving effects on HUA by ameliorating gut-kidney axis dysfunction.

Analysis of the Amine Submetabolome Using Novel Isotope-Coded Pyrylium Salt Derivatization and LC-MS: Herbs and Cancer Tissues as Cases

The amine submetabolome, including amino acids (AAs) and biogenic amines (BAs), is a class of small molecular compounds exhibiting important physiological activities. Here, a new pyrylium salt named 6,7-dimethoxy-3-methyl isochromenylium tetrafluoroborate ([d₀]-DMMIC) with stable isotope-labeled reagents ([d₃]-/[d₆]-DMMIC) was designed and synthesized for amino compounds. [d₀]-/[d₃]-/[d₆]-DMMIC-derivatized had a charged tag and formed a set of molecular ions with an increase of 3.02 m/z and the characteristic fragment ions of m/z 204.1:207.1:210.1. When DMMIC coupled with liquid chromatography-mass spectrometry (LC-MS), a systematic methodology evaluation for quantitation proved to have good linearity (R² between 0.9904 and 0.9998), precision (interday: 2.2-21.9%; intraday: 1.0-19.7%), and accuracy (recovery: 71.8-108.8%) through the test AAs. Finally, the methods based on DMMIC and LC-MS demonstrated the advantaged application by the nontargeted screening of BAs in a common medicinal herb Senecio scandens and an analysis of metabolic differences among the amine submetabolomes between the carcinoma and paracarcinoma tissues of esophageal squamous cell carcinoma (ESCC). A total of 20 BA candidates were discovered in S. scandens as well as the finding of 13 amine metabolites might be the highest-potential differential metabolites in ESCC. The results showed the ability of DMMIC coupled with LC-MS to analyze the amine submetabolome in herbs and clinical tissues.

Astragaloside IV improves the pharmacokinetics of febuxostat in rats with hyperuricemic nephropathy by regulating urea metabolism in gut microbiota

Hyperuricemic nephropathy (HN) is a common clinical complication of hyperuricemia. The pathogenesis of HN is directly related to urea metabolism in the gut microbiota. Febuxostat, a potent xanthine oxidase inhibitor, is the first-line drug used for the treatment of hyperuricemia. However, there have been few studies on the pharmacokinetics of febuxostat in HN animal models or in patients. In this study, a high-purine diet-induced HN rat model was established. The pharmacokinetics of febuxostat in HN rats was evaluated using LC-MS/MS. Astragaloside IV (AST) was used to correct the abnormal pharmacokinetics of febuxostat. Gut microbiota diversity analysis was used to evaluate the effect of AST on gut microbiota. The results showed that the delayed elimination of febuxostat caused drug accumulation after multiple administrations. Oral but not i. p. AST improved the pharmacokinetics of febuxostat in HN rats. The mechanistic study showed that AST could regulate urea metabolism in faeces and attenuate urea-ammonia liver-intestine circulation. Urease-related genera, including Eubacterium, Parabacteroides, Ruminococcus, and Clostridia, decreased after AST prevention. In addition, the decrease in pathogenic genera and increase in short-chain fatty acids (SCFA) producing genera also contribute to renal function recovery. In summary, AST improved the pharmacokinetics of febuxostat in HN rats by comprehensive regulation of the gut microbiota, including urea metabolism, anti-calcification, and short-chain fatty acid generation. These results imply that febuxostat might accumulate in HN patients, and AST could reverse the accumulation through gut microbiota regulation.

Modified Baihu decoction therapeutically remodels gut microbiota to inhibit acute gouty arthritis

Background: Acute gouty arthritis (AGA) is the most common first symptom of gout, and the development of gout as a metabolic and immune inflammatory disease is also correlated with the gut microbiota. However, the mechanism of the effect of changes in the gut microbiota on AGA remains unclear. The intestinal flora can not only affect purine metabolism or regulate inflammation, but also influence the therapeutic effect of drugs on AGA. The aim of this study was to investigate the exact mechanism of modified Baihu decoction (MBD) in the treatment of AGA and whether it is related to the regulation of the structure of the intestinal flora. Methods: On the 21st day of MBD administration by continuous gavage, a rat acute gouty arthritis model was constructed using sodium urate (0.1 mL/rat, 50 mg/mL), and the ankle joint swelling was measured before and 4 h, 8 h, 24 h, and 48 h after the injection of sodium urate. After 48 h of sodium urate injection, serum, liver, kidney, ankle synovial tissue and feces were collected from rats. The collected samples were examined and analyzed using H&E, Elisa, Immunohistochemistry, Histopathology, 16S rDNA, and Biochemical analysis. To investigate the mechanism of MBD to alleviate AGA using pro-inflammatory factors and intestinal flora. Results: MBD (5.84, 35 g/kg) was administered orally to AGA rats and diclofenac sodium tablets (DS-tablets) were used as standard treatment control. Serum biochemical assessment confirmed that MBD is a safe drug for the treatment of AGA. In addition, our findings confirmed that MBD relieved AGA-related symptoms, such as toe swelling. Lowering serum levels of uric acid, IL-1β, and TGF-β1 immunohistochemical results also confirmed that MBD reduced the expression of inflammatory elements such as IL-1β, NLRP3, ASC, and Caspase-1 in synovial tissue.Furthermore, compared with control group, the 16s rDNA sequencing of AGA rat faeces revealed an increase in the relative abundance of Lachnospiraceae, Muribaculaceae, and Bifidobacteriaceae species. While the relative abundance of Lactobacillaceae, Erysipelotrichaceae, Ruminococcaceae, Prevotellaceae and Enterobacteriaceae showed a relative decrease in species abundance. Of these, the reduction in species abundance of Enterobacteriaceae was associated with a reduction in amino acid metabolism and environmental perception. After MBD therapeutic intervention, the disturbance of the intestinal flora caused by AGA was restored. Conclusion: In summary, MBD is an effective agent for the treatment of AGA, with the potential mechanism being the regulation of intestinal flora to control inflammation. This would help to promote the therapeutic effect of MBD on AGA.

Effect of Bining decoction on gouty nephropathy: a network pharmacology analysis and preliminary validation of gut microbiota in a mouse model

Background

To use network pharmacology and gut microbiota sequencing to investigate the probable mechanism of Bining decoction (BN) in the treatment of gouty nephropathy (GN).

Methods

Firstly, the mechanism of therapeutic effects of BN on GN were collected by integrating network pharmacology. Secondly, the treatment effects of BN against GN in 30 Institute of Cancer Research (ICR) mice were evaluated by performing biochemical tests [uric acid, blood urea nitrogen, and creatinine (UA, BUN, and Cr)] and evaluating the renal weight index. Finally, 16S rRNA sequencing was utilized for elucidating the therapeutical effect of BN in GN.

Results

The results of gut microbiota sequencing analysis showed the abundance of Faecalibaculum, Romboutsia, Bifidobacterium, Bacteroides, Odoribacter, Lachnospiraceae NK4A136 group, unclassified_f__Lachnospiraceae, Roseburia, norank_f__Lachnospiraceae, Lactobacillus, Dubosiella, norank_f__Muribaculaceae, and Turicibacter in the BN group had a significant changed between-group comparisons. Using a network pharmacology-related database, 413 active components of BN were identified, as well as 1,085 GN-associated targets. The 118 targets of disease targets and component targets were mapped, of which the top 10 genes were selected. The Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that 157 pathways were enriched, which was partially consistent with the metabolic pathways of gut microbiota sequencing analysis.

Conclusions

Combining 16S rRNA gene sequencing and network pharmacology analysis, similar signaling pathways were followed: "Pathways in cancer" and "Adipocytokine signaling pathway". The results reveal that BN increases the abundance of Turicibacter, regulates the expression of JAK2 in the JAK/STAT pathway, increases the beneficial bacteria Turicibacter associated with intestinal butyric acid, which could enhance the intestinal barrier, and exert anti-inflammatory effects.

The Therapeutic Effect and the Potential Mechanism of Flavonoids and Phenolics of Moringa oleifera Lam. Leaves against Hyperuricemia Mice

The aim of this study is to evaluate the anti-hyperuricemia effect and clarify the possible mechanisms of flavonoids and phenolics of MOL (MOL-FP) in mice. Hyperuricemia mice were generated via intraperitoneal (i.p.) administration of potassium oxonate (PO) and oral gavage (p.o.) of hypoxanthine (HX). Serum uric acid (UA), weight, serum XO activity, hepatic XO activity, urea nitrogen (BUN), creatinine (CRE), serum AST level, serum ALT level, mRNA expression of renal urate-anion transporter 1 (URAT1), glucose transporter 9 (GLUT9), organic anion transporters 1 (OAT1), organic anion transporters 3 (OAT3), and ATP-binding cassette transporter G2 (ABCG2) were determined. The molecular docking was conducted using AutoDock Vina 1.2.0 to screen potential XO inhibitors in MOL-FP. Serum metabolomics was established to collect the metabolic profiles of mice and explore the metabolic changes that occurred after MOL-FP treatment. MOL-FP could notably reduce the serum UA level of hyperuricemia mice by inhibiting XO activity and regulating renal urate transporters. Molecular docking studies indicated that 5-p-coumaroylquinic acid, 3-p-coumaroylquinic acid, and catechin could be potential XO inhibitors. Besides, MOL-FP prevented the pathological process of hyperuricemia by regulating biomarkers associated with purine metabolism, amino acid metabolism, and lipid metabolism.

The anti-inflammatory effects of Hedyotis diffusa Willd on SLE with STAT3 as a key target

ETHNOPHARMACOLOGICAL RELEVANCE

Hedyotis diffusa Willd, also named Scleromitrion diffusum (Willd.) R.J. Wang, is one medical herb, which has been traditionally used by the She nationality in China. And H. diffusa represents a beneficial effect on Systemic lupus erythematosus (SLE) treatment in clinic.

AIM OF THE STUDY

The underlying mechanisms of the protective effects of H. diffusa on SLE remain unclear. In this study, we treated MRL/lpr mice with H. diffusa water extract (HDW) to assess its therapeutic effects and verified its regulating signalling pathway through cytological experiments.

MATERIALS AND METHODS

In the present study, the constituents of HDW were analysed through ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and SCIEX OS software. The protective activity and underlying mechanisms were studied in a MRL/lpr lupus mouse model. The blood cells, autoantibodies, metabolites and the cytokines in serum were identified with a hematology analyzer, specific ELISA kit, GC/MS system and cytometric assays. The histological and immunohistochemical analysis were engaged in the morphologic, and the expression and translocation of the crucial protein observation. The dual luciferase reporter assay was applied to identifying the regulative activity of HDW. The transcription and translation expression of the protein was studied by real-time PCR and Western blot assays. The network pharmacology analysis was employed to predict the IL-6/STAT3 pathway regulators and the screen the STAT3 inhibitors in HDW.

RESULTS

The results revealed the capability of HDW to attenuate the production of autoantibodies, secretion of inflammatory cytokines (IL-6 and IFN-γ), and suppressed the IgG and C3 deposition, the development of glomerular lesions in MRL/lpr mice. Serum metabolomics study showed the improvement in serum metabolites, especially aminoacyl-tRNA biosynthesis, by HDW. IL-6 was clarified to be highly associated with the significantly changed metabolites in network analysis. We further demonstrated the effects of HDW on the IL-6/STAT3 pathway in vivo and in vitro.

CONCLUSIONS

This study suggested that HDW exerts a therapeutic effect in SLE model mice by suppressing the IL-6/STAT3 pathway.

Hydroxyurea ameliorates atherosclerosis in ApoE-/- mice by potentially modulating Niemann-Pick C1-like 1 protein through the gut microbiota

Rationale: The efficacy and mechanism of hydroxyurea in the treatment of atherosclerosis have rarely been reported. The goal of this study was to investigate the efficacy of hydroxyurea in high-fat diet-fed ApoE^-/- mice against atherosclerosis and examine the possible mechanism underlying treatment outcomes. Methods: ApoE^-/- mice were fed a high-fat diet for 1 month and then administered hydroxyurea by gavage continuously for 2 months. Aortic root hematoxylin-eosin (H&E) staining and oil red O staining were used to verify the efficacy of hydroxyurea; biochemical methods and ELISA were used to detect changes in relevant metabolites in serum. 16S rRNA was used to detect composition changes in the intestinal bacterial community of animals after treatment with hydroxyurea. Metabolomics methods were used to identify fecal metabolites and their changes. Immunohistochemical staining and ELISA were used for the localization and quantification of intestinal NPC1L1. Results: We showed that aortic root HE staining and oil red O staining determined the therapeutic efficacy of hydroxyurea in the treatment of atherosclerosis in high-fat diet-fed ApoE^-/- mice. Serological tests verified the ability of hydroxyurea to lower total serum cholesterol and LDL cholesterol. The gut microbiota was significantly altered after HU treatment and was significantly different from that after antiplatelet and statin therapy. Meanwhile, a metabolomic study revealed that metabolites, including stearic acid, palmitic acid and cholesterol, were significantly enriched in mouse feces. Further histological and ELISAs verified that the protein responsible for intestinal absorption of cholesterol in mice, NPC1L1, was significantly reduced after hydroxyurea treatment. Conclusions: In high-fat diet-fed ApoE^-/- mice, hydroxyurea effectively treated atherosclerosis, lowered serum cholesterol, modulated the gut microbiota at multiple levels and affected cholesterol absorption by reducing NPC1L1 in small intestinal epithelial cells.

Extracellular vesicles isolated from hyperuricemia patients might aggravate airway inflammation of COPD via senescence-associated pathway

BACKGROUNDS

Chronic obstructive pulmonary disease (COPD) is a major health issue resulting in significant mortality worldwide. Due to the high heterogeneity and unclear pathogenesis, the management and therapy of COPD are still challenging until now. Elevated serum uric acid(SUA) levels seem to be associated with the inflammatory level in patients with COPD. However, the underlying mechanism is not yet clearly established. In the current research, we aim to elucidate the effect of high SUA levels on airway inflammation among COPD patients.

METHODS

Through bioinformatic analysis, the common potential key genes were determined in both COPD and hyperuricemia (HUA) patients. A total of 68 COPD patients aged 50-75-year were included in the study, and their clinical parameters, including baseline characteristics, lung function test, as well as blood chemistry test were recorded. These parameters were then compared between the COPD patients with and without HUA. Hematoxylin & Eosin (HE), immunofluorescence (IF), and Masson trichrome staining were performed to demonstrate the pathological changes in the lung tissues. Furthermore, we isolated extracellular vesicles (EVs) from plasma, sputum, and bronchoalveolar lavage fluid (BALF) samples and detected the expression of inflammatory factor (Interleukin-6 (IL-6), IL-8 and COPD related proteases (antitrypsin and elastase) between two groups. Additionally, we treated the human bronchial epithelial (HBE) cells with cigarette smoke extract (CSE), and EVs were derived from the plasma in vitro experiments. The critical pathway involving the relationship between COPD and HUA was eventually validated based on the results of RNA sequencing (RNA-seq) and western blot (WB).

RESULTS

In the study, the COPD patients co-existing with HUA were found to have more loss of pulmonary function compared with those COPD patients without HUA. The lung tissue samples of patients who had co-existing COPD and HUA indicated greater inflammatory cell infiltration, more severe airway destruction and even fibrosis. Furthermore, the high SUA level could exacerbate the progress of airway inflammation in COPD through the transfer of EVs. In vitro experiments, we determined that EVs isolated from plasma, sputum, and BALF played pivotal roles in the CSE-induced inflammation of HBE. The EVs in HUA patients might exacerbate both systemic inflammation and airway inflammatory response via the senescence-related pathway.

CONCLUSION

The pulmonary function and clinical indicators of COPD patients with HUA were worse than those without HUA, which may be caused by the increased airway inflammatory response through the EVs in the patient's peripheral blood. Moreover, it might mediate the EVs via senescence-related pathways in COPD patients with HUA.

Shouhui Tongbian Capsule ameliorates constipation via gut microbiota-5-HT-intestinal motility axis

Constipation has become an epidemic enteric medical problem, accompanied with increasing long-term sequelae. Gut microbiota and serotonin (5-HT) have been believed as predominant player in the treatment of constipation. In clinical practices, Shouhui Tongbian Capsule (SHTB) was found to effectively improve constipation symptoms and promote gastrointestinal motility. However, the specific mechanism of SHTB is not clearly elucidated. Our current study aims to explore the therapeutic effects of SHTB against the development of constipation and the underlying mechanisms related to gut bacterial and 5-HT. We established loperamide hydrochloride (LH)-induced experimental constipation mouse model to evaluate the effect of SHTB. 16S RNA sequencing, fecal microbiota transplants (FMT), high performance liquid chromatograph, and molecular biological analysis were performed to investigate the potential mechanisms of SHTB. Our data demonstrated that SHTB significantly ameliorated LH-induced experimental constipation and accelerated enteric motility via promoting 5-HT biosynthesis in enterochromaffin cells and enteric neuron growth of the enteric nervous system (ENS) in both the small intestine and colon. Additionally, SHTB significantly modulated gut microbiota dysbiosis and potentially altered microbiota metabolites to enhance intestinal 5-HT production. Finally, FMT study confirmed that the effects of SHTB on 5-HT production and constipation are dependent on modulating intestinal microbiota dysbiosis. In conclusion, our current study deciphered therapeutic mechanism of SHTB in the treatment of experimental constipation from perspectives of gut microbiota-5-HT-intetinal motility axis and provides novel insights into the appropriate and safe application of SHTB in the clinic.

Gut microbiota-derived metabolites in inflammatory diseases based on targeted metabolomics

The gut microbiota plays an important role in inflammatory diseases. Metabolites in the three metabolic pathways of tryptophan (Trp), histidine (His), and phenylalanine (Phe) can affect various inflammatory conditions, such as obesity, diabetes, arthritis, colitis, atherosclerosis, and neuroinflammation. We established an LC–MS/MS method to measure 17 metabolites—Trp, 3-indole-acetic acid (Iaa), 3-indole-lactate (Ila), 3-indole-propionic acid (Ipa), 3-indole formaldehyde (Iald), kynurenine (Kn), kynurenic acid (Kyna), 3-Hydroxyanthranilic acid (3-Haa), His, 3-methylhistidine (3-Mhis), histamine (Hist), imidazole propionic acid (Imp), 4-imidazoacetic acid (Imaa), urocanic acid (Ua), Phe, phenylethylamine (Pea), and hippuric acid (Ha)—in the three metabolic pathways. The method exhibited high sensitivity and good selectivity, linearity, accuracy, precision, stability; and recovery rate; all met the requirements of biological sample analysis. By establishing a rheumatoid arthritis (RA) model of Sprague–Dawley rats and performing 16S rRNA sequencing on their feces, it was found that there was dysbiosis, including changes in phylum level, genus level, and α biodiversity of gut bacteria. The contents of the microbiota metabolites Iaa and Ipa in the model group were significantly decreased, and those of Iald, Kn, Kyna, Ha, and Imp were significantly increased. The common therapeutic drugs Tripterygium glycosides, total glucosides of peony, and their main active ingredients were screened by in vitro incubation with gut bacteria: it was found that Tripterygium glycosides and their active ingredients could lead to a variation in metabolites in the Trp and Phe pathways. Total glucosides and active components of peony could lead to a variation in metabolites in the Phe pathway of the gut microbiota.

Preparation of an isorhamnetin phospholipid complex for improving solubility and anti-hyperuricemia activity

To improve the solubility and anti-hyperuricemia activity of the insoluble natural flavonoid isorhamnetin (ISO), an isorhamnetin phospholipid complex (ISO-PC) was prepared. ISO-PC was prepared through solvent evaporation and its prescription process was optimized. The formation of ISO-PC was verified via multiple characterization methods. Parameters such as drug loading, solubility, octanol-water partition coefficient, stability, and in vivo anti-hyperuricemia activity of ISO-PC were investigated. The complexation efficiency of ISO-PC was 95.1% ± 0.56%. The characterization results confirmed that ISO-PC was bound by intermolecular interactions between ISO and phospholipids. Compared to ISO, the solubility of ISO-PC in water and 1-octanol increased by 122 and 16.5 times, respectively. Additionally, the octanol-water partition coefficient decreased to 1.08. Pharmacodynamic studies have reported that ISO-PC has a more significant effect on reducing serum uric acid levels and renal protection. In conclusion, the findings of this study suggested that ISO-PC could be used as a promising formulation to improve the solubility and the anti-hyperuricemia activity of ISO.

Probiotics, bioactive compounds and dietary patterns for the effective management of hyperuricemia: a review

Hyperuricemia is closely linked with an increased risk of developing hypertension, diabetes, renal failure and other metabolic syndromes. Probiotics, bioactive compounds and dietary patterns are safe cost-efficient ways to control hyperuricemia, whereas comprehensive reviews of their anti-hyperuricemic mechanisms are limited. This review summarizes the roles of probiotics, bioactive compounds and dietary patterns in treating hyperuricemia and critically reviews the possible mechanisms by which these interventions exert their activities. The dietary patterns are closely related to the occurrence of hyperuricemia through the indirect action of gut microbiota or the direct effects of host purine metabolism. The Mediterranean and Dietary Approaches to Stop Hypertension diets help reduce serum uric acid concentrations and thus prevent hyperuricemia. Meanwhile, probiotics alleviate hyperuricemia by ways of absorbing purine, restoring gut microbiota dysbiosis and inhibiting xanthine oxidase (XO) activity. Bioactive compounds such as polyphenols, peptides and alkaloids exert various anti-hyperuricemic effects, by regulating urate transporters, blocking the active sites of XO and inhibiting the toll-like receptor 4/nuclear factor kappa B signaling pathway and NOD-, LRR- and pyrin domain-containing protein 3 signaling pathway. This review will assist people with hyperuricemia to adopt a healthy diet and contribute to the application of natural products with anti-hyperuricemic activity.

Does seasonality of the microbiota contribute to the seasonality of acute gout flare?

Gout, the most common inflammatory arthritis worldwide, is an auto-inflammatory metabolic disease that leads to monosodium urate crystal deposition. Hyperuricaemia is a significant risk factor for the development of gout; however, hyperuricaemia alone is not sufficient to induce gout.Gout flares have circadian rhythms. Gout flares vary during the day and have strong seasonality, with flares being more common in the spring. The reasons for the predominance of flares in the spring are unclear since serum urate (SU) levels show seasonal variation; however, SU levels are highest in the summer.Immune function varies significantly throughout the year, with enhanced immune responses increasing during the winter. In addition, chronic disruption of circadian rhythms is associated with metabolic syndrome and diseases driven by metabolism. The most telling example relates to Xanthine oxidase (XOD/XDH). The analysis of XOD/XDH established its circadian regulation and demonstrated that inhibition of the activity of XOD is characterised by distinct, crossregulating diurnal/seasonal patterns of activity.The gastrointestinal microbiota of gout patients is highly distinct from healthy individuals. In a small series of gout patients, Bacteroides caccae and Bacteroides xylanisolvens were found to be enriched. Bacteroidales levels were highest during the spring and summer, and loading values were highest in the spring.Our review discusses gout's circadian rhythm and seasonality, possible influences of the microbiome on gout due to our new knowledge that Bacteroidales levels were highest during spring when gout is most common, and potential opportunities for treatment based on our current understanding of this interaction.

Chlorogenic Acid Prevents Hyperuricemia Nephropathy via Regulating TMAO-Related Gut Microbes and Inhibiting the PI3K/AKT/mTOR Pathway

Hyperuricemia is an independent hazard factor of renal injury and can induce renal fibrosis, promoting the development of chronic kidney disease (CKD). This study aimed to explore the probability of chlorogenic acid (CGA) as a potential substance for preventing hyperuricemia nephropathy (HN). Pretreatment with CGA downregulated SUA, BUN, and CR levels, relieved oxidative stress and inflammatory response, alleviated kidney fibrosis, and contributed to the prevention of HN. In the gut microbiota, Blautia, Enterococcus, and Faecalibaculum related to trimethylamine N-oxide (TMAO) synthesis were significantly increased in HN rats. In addition, it showed a significant increase in serum TMAO content in HN rats. However, CGA regulated the cascade response of the microbiota-TMAO signaling to reverse the increase of serum TMAO. CGA also decreased the protein expression of protein kinase B (AKT) phosphorylation, phosphatidylinositide 3-kinase (PI3K), and mammalian target of rapamycin (mTOR) by reducing the production of TMAO. CGA delayed kidney fibrosis in HN rats as evidenced by regulating the cascade response of the microbiota-TMAO-PI3K/AKT/mTOR signaling pathway. In summary, CGA can be an excellent candidate for HN prevention.

Investigation of pathogenesis of hyperuricemia based on untargeted and targeted metabolomics

Hyperuricemia (HUA) seriously harms human health but the exact etiology and pathogenesis of HUA are not fully understood. Therefore, it is still of great significance to find effective biomarkers and explore the pathogenesis of HUA. Metabolomics reflects the influence of internal and external factors on system metabolism, explains the changes in metabolite levels during the development of diseases, and reveals the molecular mechanism of pathogenesis. Metabolomics is divided into untargeted metabolomics and targeted metabolomics according to different research modes. Each other's advantages can be fully utilized by combining the two so that the results of metabolomics research can be consummated. 20 HUA patients and 20 healthy individuals participated in the experiment, and untargeted metabolomics was employed to find 50 differential metabolites in HUA serum samples. Twelve candidate biomarkers were screened based on literature research and ROC Curve analysis for subsequent verification. Based on the UPLC-TQ-MS analysis platform, the targeted metabolomics detection methods were established and the content of 12 candidate biomarkers was precisely quantified. Compare with the results of untargeted metabolomics, the targeted metabolomics results were considered more reliable.

Gut microbiota remodeling: A promising therapeutic strategy to confront hyperuricemia and gout

The incidence of hyperuricemia (HUA) and gout continuously increases and has become a major public health problem. The gut microbiota, which colonizes the human intestine, has a mutually beneficial and symbiotic relationship with the host and plays a vital role in the host's metabolism and immune regulation. Structural changes or imbalance in the gut microbiota could cause metabolic disorders and participate in the synthesis of purine-metabolizing enzymes and the release of inflammatory cytokines, which is closely related to the occurrence and development of the metabolic immune disease HUA and gout. The gut microbiota as an entry point to explore the pathogenesis of HUA and gout has become a new research hotspot. This review summarizes the characteristics of the gut microbiota in patients with HUA and gout. Meanwhile, the influence of different dietary structures on the gut microbiota, the effect of the gut microbiota on purine and uric acid metabolism, and the internal relationship between the gut microbiota and metabolic endotoxemia/inflammatory factors are explored. Moreover, the intervention effects of probiotics, prebiotics, and fecal microbial transplantation on HUA and gout are also systematically reviewed to provide a gut flora solution for the prevention and treatment of related diseases.

Metabolites Analysis of Anti-Myocardial Ischemia Active Components of Saussurea involucrata Based on Gut Microbiota-Drug Interaction

Saussurea involucrata has been reported to have potential therapeutic effects against myocardial ischemia. The pharmacological effects of oral natural medicines may be influenced by the participation of gut microbiota. In this study, we aimed to investigate the bidirectional regulation of gut microbiota and the main components of Saussurea involucrata. We first established a quantitative method for the four main components (chlorogenic acid, syringin, acanthoside B, rutin) which were chosen by fingerprint using liquid chromatography tandem mass spectrometry (LC-MS/MS), and found that gut microbiota has a strong metabolic effect on them. Meanwhile, we identified five major rat gut microbiota metabolites (M1-M5) using liquid chromatography tandem time-of-flight mass spectrometry (LC/MSn-IT-TOF). The metabolic properties of metabolites in vitro were preliminarily elucidated by LC-MS/MS for the first time. These five metabolites of Saussurea involucrata may all have potential contributions to the treatment of myocardial ischemia. Furthermore, the four main components (10 μg/mL) can significantly stimulate intestinal bacteria to produce short chain fatty acids in vitro, respectively, which can further contribute to the effect in myocardial ischemia. In this study, the therapeutic effect against myocardial ischemia of Saussurea involucrata was first reported to be related to the intestinal flora, which can be useful in understanding the effective substances of Saussurea involucrata.

The Interaction Between Dietary Fructose and Gut Microbiota in Hyperuricemia and Gout

With the worldwide epidemics of hyperuricemia and associated gout, the diseases with purine metabolic disorders have become a serious threat to human public health. Accumulating evidence has shown that they have been linked to increased consumption of fructose in humans, we hereby made a timely review on the roles of fructose intake and the gut microbiota in regulating purine metabolism, together with the potential mechanisms by which excessive fructose intake contributes to hyperuricemia and gout. To this end, we focus on the understanding of the interaction between a fructose-rich diet and the gut microbiota in hyperuricemia and gout to seek for safe, cheap, and side-effect-free clinical interventions. Furthermore, fructose intake recommendations for hyperuricemia and gout patients, as well as the variety of probiotics and prebiotics with uric acid-lowering effects targeting the intestinal tract are also summarized to provide reference and guidance for the further research.

Hypouricemic effect of 2,4-dihydroxybenzoic acid methyl ester in hyperuricemic mice through inhibiting XOD and down-regulating URAT1

In this paper, we reported the hypouricemic effect of 2,4-dihydroxybenzoic acid methyl ester (DAE), a component of Ganoderma applanatum, in hyperuricemic mice through inhibiting XOD and down-regulating URAT1. Computationally, DAE showed a high similarity to allopurinol and depicted a high affinity in docking to XOD. In vitro, DAE exhibited an inhibitory effect against XOD. Importantly, DAE demonstrated a remarkable hypouricemic effect, decreasing serum uric acids (SUAs) of hyperuricemic mice (407 ± 31 μmol/L) to 195 ± 23, 145 ± 33 and 134 ± 16 μmol/L (P < 0.01) at the doses of 20, 40, and 80 mg/kg with a dose-dependent manner and showing efficacies at 54-68 %, which were close to the efficacies of allopurinol (61 %) and benzbromarone (57 %). DAE depicted higher and negatively dose-independent urinary uric acids in comparison with that of the hyperuricemic control, implying DAE exerted an uricosuric effect and also a reduction effect on uric acid production. Unlike toxic allopurinol and benzbromarone, no general toxicity on body weights and no negative influence on liver, kidney, spleen and thymus were observed for DAE. Mechanistically, DAE inhibited XOD activities in vivo. Moreover, DAE up-regulated OAT1 and down-regulated GLUT9, URAT1 and CNT2. Overall, DAE may present a hypouricemic effect through inhibiting XOD and up-regulating OAT1 and down-regulating GLUT9, URAT1 and CNT2. This work provided novel insights into the hypouricemic effect of DAE and G. applanatum.

Tea and its components reduce the production of uric acid by inhibiting xanthine oxidase

Background

The health benefits of tea are as diverse including the reduction of uric acid levels. Xanthine oxidase is the most directly mediated enzyme in the production of uric acid.

Objective

To explore the inhibitory effects of different teas and its main bioactive components on the production of uric acid.

Design

Experimental study. The experiments were conducted in vitro using human immortalized normal liver cell line HL-7702 (L-02).

Results

The inhibition of the xanthine oxidase activities and the expression level of xanthine dehydrogenase mRNA stimulated in the hyperuric hepatocyte cell model showed that the unfermented green tea and th1e lightly fermented yellow tea, white tea, and oolong tea significantly stronger than the highly fermented black tea and dark tea. The main bioactive compound, gallic acid, showed the strongest inhibitory effect on uric acid production, followed by tea polyphenols and theaflavins.

Discussion

All teas exhibited significant inhibition of xanthine oxidase activities, and the degree of fermentation of tea may be inversely proportional to its ability to inhibit the production of uric acid. Compared with tea polyphenols rich in tea, gallic acid may be a more potential uric acid-lowering component.

Conclusion

In this article, we first compared the effects of six traditional Chinese tea made from a single variety in stabilizing the synthesis of uric acid and found that the lighter the fermentation, the greater the potential for inhibiting the production of uric acid. Furthermore, we analyzed the inhibitory effects of its main biochemical active ingredients and found that the inhibitory effects of polyphenols rich in lightly fermented tea were significantly stronger than caffeine rich in highly fermented tea. Our findings will be helpful for people to choose a proper tea for alleviating hyperuricemia and provide a scientific basis for uric acid-lowering tea processing.

Optimized UV-Spectrophotometric Assay to Screen Bacterial Uricase Activity Using Whole Cell Suspension

Uricase catalyzes the conversion of uric acid into allantoin with concomitant reduction of molecular oxygen to hydrogen peroxide. In humans, uricase is not functional, thereby predisposing individuals to hyperuricemia, a metabolic disturbance associated with gout, chronic kidney disorders, and cardiovascular diseases. The efficacy of current therapies to treat hyperuricemia is limited, and novel approaches are therefore desired, for instance using uricase-expressing probiotic strains. Here, we evaluated UV-spectrophotometric and H₂O₂-based fluorescent assays to enable the rapid identification of uricase activity in a broad panel of lactobacilli, Bacillus, and Bifidobacterium species. We highlighted abiotic (medium composition and mode of sterilization) and biotic (H₂O₂-producing strains) factors impacting the measurements' accuracy, and reported on the stepwise optimization of a simple, fast, and robust high-throughput UV-spectrophotometric method to screen uricase activity using whole bacterial suspension, thereby assessing both cell-associated and extracellular activity. The validity of the optimized assay, based on the monitoring of uric acid degradation at 300 nm, was confirmed via liquid chromatography. Finally, a panel of 319 Qualified Presumption of Safety (QPS) strains of lactobacilli (18 species covering nine genera), Bacillus (three species), and Bifidobacterium (four species) were screened for uricase activity using the optimized method. All 319 strains, but the positive control Bacillus sp. DSM 1306, were uricase-negative, indicating that this activity is rare among these genera, especially in isolates from food or feces. Altogether, the UV-spectrophotometric high-throughput assay based on whole bacterial suspension reported here can be used to rapidly screen large microbial collections, by simultaneously detecting cell-associated and extracellular uricase activity, thereby accelerating the identification of uricolytic strains with therapeutic potential to treat hyperuricemia.

Differential colitis susceptibility of Th1- and Th2-biased mice: A multi-omics approach

The health and economic burden of colitis is increasing globally. Understanding the role of host genetics and metagenomics is essential to establish the molecular basis of colitis pathogenesis. In the present study, we have used a common composite dose of DSS to compare the differential disease severity response in C57BL/6 (Th1 biased) and BALB/c (Th2 biased) mice with zero mortality rates. We employed multi-omics approaches and developed a newer vector analysis approach to understand the molecular basis of the disease pathogenesis. In the current report, comparative transcriptomics, metabonomics, and metagenomics analyses revealed that the Th1 background of C57BL/6 induced intense inflammatory responses throughout the treatment period. On the contrary, the Th2 background of BALB/c resisted severe inflammatory responses by modulating the host’s inflammatory, metabolic, and gut microbial profile. The multi-omics approach also helped us discover some unique metabolic and microbial markers associated with the disease severity. These biomarkers could be used in diagnostics.

Kidney and plasma metabolomics provide insights into the molecular mechanisms of urate nephropathy in a mouse model of hyperuricemia

Hyperuricemia (HUA) is closely associated with kidney damage and kidney diseases in humans; however, the underlying mechanisms of HUA-induced kidney diseases remain unknown. In the present study, we examined the kidney and plasma metabolic profiles in a HUA mouse model constructed by knocking out (Ko) the urate oxidase (Uox) gene. The Uox-Ko mice were characterized by an increase in uric acid, glycine, 3'-adenosine monophosphate, citrate, N-acetyl-l-glutamate, l-kynurenine, 5-hydroxyindoleacetate, xanthurenic acid, cortisol, and (-)-prostaglandin e2 together with a decrease of inosine in the kidneys. These altered metabolites confirmed disturbances of purine metabolism, amino acid biosynthesis, tryptophan metabolism, and neuroactive ligand-receptor interaction in Uox-Ko mice. Betaine and biotin were related to kidney function and identified as the potential plasma metabolic biomarker for predicting urate nephropathy (UN). Taken together, these results revealed the underlying pathogenic mechanisms of UN. Investigating these pathways might provide novel targets for the therapeutic intervention of UN and can potentially lead to new treatment strategies.

The effect of a novel anticonvulsant chemical Q808 on gut microbiota and hippocampus neurotransmitters in pentylenetetrazole-induced seizures in rats

Background

The gut microbiota can modulate brain function and behavior and is increasingly recognized as an important factor in mediating the risk of epilepsy and the effects of seizure interventions. Drug therapy is one of the factors that influence the composition of the intestinal microbiota. Q808 is an innovative chemical with strong anticonvulsant activity and low neurotoxicity. However, studies evaluating the effect of Q808 on gut microbial communities are lacking. In this study, we aimed to evaluate the anticonvulsant activity of Q808 on a pentylenetetrazol (PTZ)—induced seizure model and analyze and compare the intestinal microbiota composition of non-PTZ vehicle control group, the PTZ-induced seizure model rats with and without Q808, through 16S rDNA sequencing. Neurotransmitter levels in the hippocampus were quantitatively estimated using HPLC–MS.

Results

The results suggest that Q808 effectively alleviates seizures in chronic PTZ-kindled model rats. Additionally, based on the analyzed abundance of the gut microbiota, dysbacteriosis of model rats was found to be corrected after Q808 treatment at the phylum level. The unique bacterial taxa (e.g., Lactobacillus) that are associated with acetylcholine production, were significantly increased. Several short-chain fatty acids (SCFAs)-producing bacteria, including Roseburia, Alloprevptella, Prevotellaceae_NK3B31_group, Prevotellaceae_UCG-001, and Prevotella_9, were enriched. In the hippocampus, the contents of acetylcholine increased, whereas the levels of 3-methoxytyramine, glutamine, and 5-hydroxyindole acetic acid (5-HIAA) decreased after Q808 treatment.

Conclusions

This study demonstrates that Q808 can be used to remodel the dysbiosis of the gut microbiome and influence neurotransmitter levels in the hippocampus of PTZ-induced seizure model rats. We hope that these novel findings prompt further research on the interaction between gut microbiota and seizures and the mechanism of Q808.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-022-00690-3.

The anti-hyperuricemic effect of flavonoid extract of saffron by-product and its pharmacokinetics in rats after oral administration

Only the dried stigma of the saffron, a flower deemed as the most valuable spice globally, is utilized for industrial production. Hence, there exists a growing interest in utilizing saffron floral bio-residues. The anti-hyperuricemic activity of a flavonoid extract from saffron floral bio-residues was assessed in potassium oxonate-induced hyperuricemia mice. In addition, an ultra-high performance liquid chromatography-triple quadrupole mass spectrometry method was established and validated to determine the pharmacokinetics of five main flavonoids and three phase-II metabolites in rat plasma after oral administration of the flavonoid extract for the first time. Compared with pharmacokinetic parameters of kaempferol-3-O-sophoroside, the most abundant flavonoid in the extract, and its aglycone kaempferol, we observed that coexisting compounds significantly reduced the absorption, accelerated the excretion of kaempferol-3-O-sophoroside, while significantly increasing the absorption and prolonging the residence time of kaempferol in the flavonoid extract. These results suggest the promising potential of the flavonoid extract from saffron floral bio-residues as an anti-hyperuricemic agent. Kaempferol was absorbed in plasma at high concentrations owing to the biotransformation of kaempferol glycosides in vivo.

Hypouricemic, hepatoprotective and nephroprotective roles of oligopeptides derived from Auxis thazard protein in hyperuricemic mice

The oligopeptides derived from Auxis thazard protein (ATO) are a class of small peptides with molecular weight <1 kDa and good bioactivity. This paper aimed to explore the hypouricemic, hepatoprotective, and nephroprotective effects of ATO and its potential mechanisms in hyperuricemia in mice induced by potassium oxonate. The results showed that ATO significantly reduced serum UA, serum creatinine levels, inhibited XOD and ADA activities in the liver (p < 0.05), and accelerated UA excretion by downregulating the gene expression of renal mURAT1 and mGLUT9 and upregulating the gene expression of mABCG2 and mOAT1. ATO could also reduce the levels of liver MDA, increase the activities of SOD and CAT, and reduce the levels of IL-1β, MCP-1 and TNF-α. Histological analysis also showed that ATO possessed hepatoprotective and nephroprotective activities in hyperuricemic mice. Thus, ATO could reduce the serum UA level in hyperuricemic mice by decreasing UA production and promoting UA excretion from the kidney, suggesting that ATO could be developed as a dietary supplement for hyperuricemia treatment.

Characterization of gut microbiota, metabolism and cytokines in benzene-induced hematopoietic damage

Benzene exposure leads to hematopoietic dysfunction and is characterized clinically by a decrease in blood cells, but the underlying mechanisms remain elusive. Disturbed gut microbiota may induce host metabolic, immune disorders and the onset of disease. However, the characterization of gut microbiota, metabolism, cytokines and their association with benzene-induced hematopoietic toxicity lacks systematic evidence. Here, the microbiomics, metabolomics and cytokine network were applied to find out the critical characteristics of gut microbiota, metabolism and cytokines in mice involved in the benzene-induced hematopoietic toxicity. We found that the decline in hematopoietic stem cells was earlier than the hematological changes in the 5 mg/kg and 25 mg/kg benzene exposure groups. While 125 mg/kg benzene exposure resulted in a significant decline in whole blood cells. High-throughput sequencing results showed that benzene exposure disrupted homeostasis of gut microbiota, metabolism and cytokine in mice. 6 bacteria, 12 plasma metabolites and 6 cytokines were associated with benzene-induced hematopoietic damage. Notably, IL-5 was significantly increased in benzene exposure group in a dose-dependent manner, and a significant negative correlation was found between IL-5 and hematopoietic damage. We further found that increased Family_XIII_AD3011_group at the genus level and decreased Anaerotruncus_sp at the species level in benzene-exposed group were strongly associated with hematopoietic toxicity and IL-5. Furthermore, the abundance of Family_XIII_AD3011_group and Anaerotruncus_sp were negatively correlated with Adipic acid and 4-Hydroxyproline, respectively. Our findings indicated that altered flora structure of gut microbiota affects the metabolic phenotype which acts as messengers for the gut microbes, affecting host inflammation. This preliminary study provides new insight into the potential mechanisms of benzene-induced hematopoietic toxicity, further exploration by functional studies is required in the future.

Dysbiosis and structural disruption of the respiratory microbiota in COVID-19 patients with severe and fatal outcomes

The COVID-19 outbreak has caused over three million deaths worldwide. Understanding the pathology of the disease and the factors that drive severe and fatal clinical outcomes is of special relevance. Studying the role of the respiratory microbiota in COVID-19 is especially important as the respiratory microbiota is known to interact with the host immune system, contributing to clinical outcomes in chronic and acute respiratory diseases. Here, we characterized the microbiota in the respiratory tract of patients with mild, severe, or fatal COVID-19, and compared it to healthy controls and patients with non-COVID-19-pneumonia. We comparatively studied the microbial composition, diversity, and microbiota structure between the study groups and correlated the results with clinical data. We found differences in the microbial composition for COVID-19 patients, healthy controls, and non-COVID-19 pneumonia controls. In particular, we detected a high number of potentially opportunistic pathogens associated with severe and fatal levels of the disease. Also, we found higher levels of dysbiosis in the respiratory microbiota of patients with COVID-19 compared to the healthy controls. In addition, we detected differences in diversity structure between the microbiota of patients with mild, severe, and fatal COVID-19, as well as the presence of specific bacteria that correlated with clinical variables associated with increased risk of mortality. In summary, our results demonstrate that increased dysbiosis of the respiratory tract microbiota in patients with COVID-19 along with a continuous loss of microbial complexity structure found in mild to fatal COVID-19 cases may potentially alter clinical outcomes in patients. Taken together, our findings identify the respiratory microbiota as a factor potentially associated with the severity of COVID-19.

Changes of Intestinal Flora and Lymphocyte Subsets in Patients with Chronic Renal Failure

OBJECTIVE

To explore the changes of intestinal flora and lymphocyte subsets in patients with chronic renal failure (CRF).

METHODS

60 CRF patients who were treated from June 2018 to June 2019 were selected; 60 healthy persons were selected as the control group. 16S rDNA was used to detect the expression of Lactobacillus, Enterobacteriaceae, Enterococcus, Bacteroides, Clostridium, and Bifidobacterium in the feces of the two groups. Illumina Miseq sequencing (Solexa sequencing technology) method was used to analyze the structural differences and species diversity of intestinal flora, including species richness index (Chao) and diversity index (Shannon, Simpson). Flow cytometry was used to detect the levels of lymphocytes and their subgroups of the two groups. Pearson correlation analysis was used to analyze the correlation between Chao and lymphocyte subsets.

RESULTS

The number of Enterobacteriaceae and Enterococcus in CRF group were higher than those in the control group (P < 0.05), while the Lactobacillus, Bacteroides, Clostridium, and Bifidobacterium were opposite (P < 0.05). The Simpson index of the CRF group was lower than that of the control group, while the Chao index and Shannon index were opposite (P < 0.05). The levels of CD3+, CD4+, CD8+, and CD4+/CD8+ in the CRF group were lower than those in the control group, while the levels of CD14+, CD19+, and CD16+/CD56+ were opposite (P < 0.05). The intestinal flora Chao index of CRF group was negatively correlated with the levels of CD3+, CD4+, and CD8+ (r = -0.692, P=0.019; r = -0.669, P=0.021; r = -0.603, P=0.028). The intestinal flora Chao of CRF group is positively correlated with the level of CD14+ and CD16+/CD56+ (r = 0.615, P=0.026; r = 0.758, P=0.016).

CONCLUSION

There are intestinal flora disorder and the imbalance of immune function in CRF patients, which are mainly manifested in the change of intestinal flora structure, the increase of richness and diversity of intestinal flora, and the decrease of lymphocyte subgroups. There is correlation between the imbalance of intestinal colony and the imbalance of immune function.

Gut Microbiota Characterization in Patients with Asymptomatic Hyperuricemia: probiotics increased

Asymptomatic hyperuricemia (AH) is an early stage of gout. Emerging evidence shows that the intestinal microbiota is related to gout. However, the relationship between AH and the intestinal microbiota is poorly understood. Therefore, the aim of the current study was to explore the possible correlation between AH and intestinal flora. We compared the intestinal microbial communities of AH (45 cases) and healthy subjects (45 cases) by 16S rRNA gene sequencing and clustering analysis on the incorporated population. Intestinal-type clustering can be divided into two groups, and significant differences in the proportion of AH are found among different bowel types. Alpha diversity indices were higher in the AH group than in the control group, and beta diversity indices also showed significant differences. A total of 19 genera were found different between the AH group and the control group. Compared with the control group, some probiotics are increased in the AH population. Two groups were ranked by importance of bacteria. We found the different bacteria partially coincided with the important bacteria, and the joint diagnosis level of the important bacteria was good. Conclusion: There were significant differences in the composition of intestinal biota between AH patients and healthy subjects. Some probiotics increased in AH.

Uric acid extrarenal excretion: the gut microbiome as an evident yet understated factor in gout development

Humans do not produce uricase, an enzyme responsible for degrading uric acid. However, some bacteria residing in the gut can degrade one-third of the dietary and endogenous uric acid generated daily. New insights based on metagenomic and metabolomic approaches provide a new interest in exploring the involvement of gut microbiota in gout. Nevertheless, the exact mechanisms underlying this association are complex and have not been widely discussed. In this study, we aimed to review the evidence that suggests uric acid extrarenal excretion and gut microbiome are potential risk factors for developing gout. A literature search was performed in PubMed, Web of Science, and Google Scholar using several keywords, including "gut microbiome AND gout". A remarkable intestinal dysbiosis and shifts in abundance of certain bacterial taxa in gout patients have been consistently reported among different studies. Under this condition, bacteria might have developed adaptive mechanisms for de novo biosynthesis and salvage of purines, and thus, a concomitant alteration in uric acid metabolism. Moreover, gut microbiota can produce substrates that might cross the portal vein so the liver can generate de novo purinogenic amino acids, as well as uric acid. Therefore, the extrarenal excretion of uric acid needs to be considered as a factor in gout development. Nevertheless, further studies are needed to fully understand the role of gut microbiome in uric acid production and its extrarenal excretion, and to point out possible bacteria or bacterial enzymes that could be used as probiotic coadjutant treatment in gout patients.

Fisetin Improves Hyperuricemia-Induced Chronic Kidney Disease via Regulating Gut Microbiota-Mediated Tryptophan Metabolism and Aryl Hydrocarbon Receptor Activation

The intestinal flora serves a critical role in the development of hyperuricemia-induced chronic kidney disease (CKD). We previously found that natural flavonol fisetin exhibited nephroprotective effects in hyperuricemic mice. However, the mechanism remains largely unknown. To investigate the underlying mechanism of fisetin, mice were fed with potassium oxonate and adenine to introduce hyperuricemia-induced CKD. Fisetin improved kidney function, ameliorated renal fibrosis, and restored enteric dysbacteriosis in hyperuricemia-induced CKD mice. Meanwhile, gut microbiota-derived tryptophan metabolites, especially l-kynurenine, showed correlations with nephroprotective profiles of fisetin. Additionally, the kidney expression of the aryl hydrocarbon receptor (AHR), an endogenous receptor of l-kynurenine, was enhanced in hyperuricemic mice and further reduced in fisetin-treated mice. Finally, in vitro results showed that inhibition of AHR activation attenuated l-kynurenine-induced fibrosis. These results highlighted that fisetin protected against hyperuricemia-induced CKD via modulating gut microbiota-mediated tryptophan metabolism and AHR activation.

Lactic acid bacteria strains relieve hyperuricaemia by suppressing xanthine oxidase activity via a short-chain fatty acid-dependent mechanism

Globally, the incidence of hyperuricaemia is steadily increasing. The evidence increasingly suggests an association between hyperuricaemia and the gut microbiota, which may enable the development of a novel therapeutic approach. We studied the effects of treatment with lactic acid bacteria (LAB) on hyperuricaemia and their potential underlying mechanisms. A mouse model of hyperuricaemia was generated by oral gavage with hypoxanthine and intraperitoneal injections of potassium oxonate for 2 weeks. The anti-hyperuricaemic activities of 10 LAB strains relative to allopurinol as a positive drug control were investigated in the mouse model. Lactobacillus rhamnosus R31, L. rhamnosus R28-1 and L. reuteri L20M3 effectively reduced the uric acid (UA) concentrations in serum and urine and the xanthine oxidase (XOD) activity levels in serum and hepatic tissue in mice with hyperuricaemia. These strains also reversed the elevated lipopolysaccharide (LPS) concentration, hepatic inflammation and slight renal injury associated with hyperuricaemia. A correlation analysis revealed that UA-reducing LAB strains promoted short-chain fatty acid (SCFA) production to suppress serum and hepatic XOD activity by increasing the abundances of SCFA production-related gut bacterial taxa. However, the UA-reducing effects of LAB strains might not be mediated by purine degradation. In summary, L. rhamnosus R31, L. rhamnosus R28-1 and L. reuteri L20M3 relieved hyperuricaemia in our mouse model by promoting SCFA production in a purine degradation-independent manner. Our findings suggest a novel therapeutic approach involving LAB strains for hyperuricaemia.

Interrogation of the perturbed gut microbiota in gouty arthritis patients through in silico metabolic modeling

Recent studies have shown perturbed gut microbiota associated with gouty arthritis, a metabolic disease characterized by an imbalance between uric acid production and excretion. To mechanistically investigate altered microbiota metabolism associated with gout disease, 16S rRNA gene amplicon sequence data from stool samples of gout patients and healthy controls were computationally analyzed through bacterial community metabolic models. Patient-specific community models constructed with the metagenomics modeling pipeline, mgPipe, were used to perform k-means clustering of samples according to their metabolic capabilities. The clustering analysis generated statistically significant partitioning of samples into a Bacteroides-dominated, high gout cluster and a Faecalibacterium-elevated, low gout cluster. The high gout cluster was predicted to allow elevated synthesis of the amino acids D-alanine and L-alanine and byproducts of branched-chain amino acid catabolism, while the low gout cluster allowed higher production of butyrate, the sulfur-containing amino acids L-cysteine and L-methionine, and the L-cysteine catabolic product H2S. By expanding the capabilities of mgPipe to provide taxa-level resolution of metabolite exchange rates, acetate, D-lactate and succinate exchanged from Bacteroides to Faecalibacterium were predicted to enhance butyrate production in the low gout cluster. Model predictions suggested that sulfur-containing amino acid metabolism generally and H2S more specifically could be novel gout disease markers.

Curcumin modulates gut microbiota and improves renal function in rats with uric acid nephropathy

It is well known that the progression of hyperuricemia disease often contributes to renal dysfunction. However, there have been few studies on uric acid nephropathy (UAN), especially its relationship with gut microbiota. UAN is usually accompanied by disordered intestinal flora, and damaged gut barrier, which are closely related to tubulointerstitial fibrosis, and systemic inflammation. In previous studies, it has been confirmed that curcumin could alleviate tubulointerstitial fibrosis, and improve renal function through its antioxidant, anti-apoptotic, and anti-inflammatory efficacies. However, the effects curcumin exerts on intestinal flora in uric acid nephropathy are still unknown. Therefore, we used next-generation sequencing technology to investigate the effects of curcumin on gut microbiota in a rat model of UAN induced by adenine and potassium oxonate, and rats were randomly divided into control, model or curcumin treatment groups. The results demonstrated that, compared to the model group, the treatment group showed decreased serum uric acid (156.80 ± 11.90 μmol/L vs. 325.60 ± 18.65 μmol/L, p < 0.001), serum creatinine (66.20 ± 11.88 μmol/L vs. 182.20 ± 8.87 μmol/L, p < 0.001) and BUN level (13.33 ± 3.16 mmol/L vs. 36.04 ± 6.60 mmol/L, p < 0.001). The treatment group also displayed attenuated renal pathological lesions and metabolic endotoxemia (25.60 ± 5.90 ng/mL vs. 38.40 ± 4.98 ng/mL, p < 0.01), and improved tightly linked proteins expression. Besides, curcumin altered the gut microbiota structure in UAN rats. More specifically, curcumin treatment protected against the overgrowth of opportunistic pathogens in UAN, including Escherichia-Shigella and Bacteroides, and increased the relative abundance of bacteria producing short‐chain fatty acids (SCFAs), such as Lactobacillus and Ruminococcaceae. These results suggest that curcumin could modulate gut microbiota, fortify the intestinal barrier, attenuate metabolic endotoxemia, and consequently protect the renal function in UAN rats.

Biotransformation of Timosaponin BII into Seven Characteristic Metabolites by the Gut Microbiota

Timosaponin BII is one of the most abundant Anemarrhena saponins and is in a phase II clinical trial for the treatment of dementia. However, the pharmacological activity of timosaponin BII does not match its low bioavailability. In this study, we aimed to determine the effects of gut microbiota on timosaponin BII metabolism. We found that intestinal flora had a strong metabolic effect on timosaponin BII by HPLC-MS/MS. At the same time, seven potential metabolites (M1–M7) produced by rat intestinal flora were identified using HPLC/MS-Q-TOF. Among them, three structures identified are reported in gut microbiota for the first time. A comparison of rat liver homogenate and a rat liver microsome incubation system revealed that the metabolic behavior of timosaponin BII was unique to the gut microbiota system. Finally, a quantitative method for the three representative metabolites was established by HPLC-MS/MS, and the temporal relationship among the metabolites was initially clarified. In summary, it is suggested that the metabolic characteristics of gut microbiota may be an important indicator of the pharmacological activity of timosaponin BII, which can be applied to guide its application and clinical use in the future.

Effects of cat ownership on the gut microbiota of owners

Pet ownership is an essential environmental exposure that might influence the health of the owner. This study’s primary objectives were to explore the effects of cat ownership on the gut microbial diversity and composition of owners. Raw data from the American Gut Project were obtained from the SRA database. A total of 214 Caucasian individuals (111 female) with cats and 214 individuals (111 female) without cats were used in the following analysis. OTU number showed significant alteration in the Cat group and Female_cat group, compared with that of the no cat (NC) group and Female_ NC group, respectively. Compared with the NC group, the microbial phylum Proteobacteria was significantly decreased in the Cat group. The microbial families Alcaligenaceae and Pasteurellaceae were significantly reduced, while Enterobacteriaceae and Pseudomonadaceae were significantly increased in the Cat group. Fifty metabolic pathways were predicted to be significantly changed in the Cat group. Twenty-one and 13 metabolic pathways were predicted to be significantly changed in the female_cat and male_cat groups, respectively. Moreover, the microbial phylum Cyanobacteria was significantly decreased, while the families Alcaligenaceae, Pseudomonadaceae and Enterobacteriaceae were significantly changed in the normal weight cat group. In addition, 41 and 7 metabolic pathways were predicted to be significantly changed in the normal-weight cat and overweight cat groups, respectively. Therefore, this study demonstrated that cat ownership could influence owners’ gut microbiota composition and function, especially in the female group and normal-weight group.

Plasma and stool metabolomics to identify microbiota derived-biomarkers of metabolic dysfunction-associated fatty liver disease: effect of PNPLA3 genotype

INTRODUCTION

Non-invasive biomarkers are needed for metabolic dysfunction-associated fatty liver disease (MAFLD), especially for patients at risk of disease progression in high-prevalence areas. The microbiota and its metabolites represent a niche for MAFLD biomarker discovery. However, studies are not reproducible as the microbiota is variable.

OBJECTIVES

We aimed to identify microbiota-derived metabolomic biomarkers that may contribute to the higher MAFLD prevalence and different disease severity in Latin America, where data is scarce.

METHODS

We compared the plasma and stool metabolomes, gene patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 single nucleotide polymorphism (SNP), diet, demographic and clinical data of 33 patients (12 simple steatosis and 21 steatohepatitis) and 19 healthy volunteers (HV). The potential predictive utility of the identified biomarkers for MAFLD diagnosis and progression was evaluated by logistic regression modelling and ROC curves.

RESULTS

Twenty-four (22 in plasma and 2 in stool) out of 424 metabolites differed among groups. Plasma triglyceride (TG) levels were higher among MAFLD patients, whereas plasma phosphatidylcholine (PC) and lysoPC levels were lower among HV. The PNPLA3 risk genotype was related to higher plasma levels of eicosenoic acid or fatty acid 20:1 (FA(20:1)). Body mass index and plasma levels of PCaaC24:0, FA(20:1) and TG (16:1_34:1) showed the best AUROC for MAFLD diagnosis, whereas steatosis and steatohepatitis could be discriminated with plasma levels of PCaaC24:0 and PCaeC40:1.

CONCLUSION

This study identified for the first time MAFLD potential non-invasive biomarkers in a Latin American population. The association of PNPLA3 genotype with FA(20:1) suggests a novel metabolic pathway influencing MAFLD pathogenesis.

Obesity-Related Gut Microbiota Aggravates Alveolar Bone Destruction in Experimental Periodontitis through Elevation of Uric Acid

Obesity is a risk factor for periodontal disease (PD). Initiation and progression of PD are modulated by complex interactions between oral dysbiosis and host responses. Although obesity is associated with increased susceptibility to bacterial infection, the detailed mechanisms that connect obesity and susceptibility to PD remain elusive. Using fecal microbiota transplantation and a ligature-induced PD model, we demonstrated that gut dysbiosis-associated metabolites from high-fat diet (HFD)-fed mice worsen alveolar bone destruction. Fecal metabolomics revealed elevated purine degradation pathway activity in HFD-fed mice, and recipient mice had elevated levels of serum uric acid upon PD induction. Furthermore, PD induction caused more severe bone destruction in hyperuricemic than normouricemic mice, and the worsened bone destruction was completely abrogated by allopurinol, a xanthine oxidase inhibitor. Thus, obesity increases the risk of PD by increasing production of uric acid mediated by gut dysbiosis.

Advances in Microbiome Detection Technologies and Application in Antirheumatic Drug Design

Rheumatic diseases are a kind of chronic inflammatory and autoimmune disease affecting the connection or supporting structures of the human body, such as the most common diseases Ankylosing spondylitis (AS), gout and Systemic lupus erythematosus (SLE). Although the precise etiology and pathogenesis of the different types of rheumatic diseases remain mostly unknown, it is now commonly believed that these diseases are attributed to some complex interactions between genetics and environmental factors, especially the gut microbiome. Altered microbiome showed clinical improvement in disease symptoms and partially restored to normality after prescribing disease-modifying antirheumatic drugs (DMARDs) or other treatment strategies. Recent advances in next-generation sequencing-based microbial profiling technology, especially metagenomics, have identified alteration of the composition and function of the gut microbiota in patients. Clinical and experimental data suggest that dysbiosis may play a pivotal role in the pathogenesis of these diseases. In this paper, we provide a brief review of the advances in the microbial profiling technology and up-to-date resources for accurate taxonomic assignment of metagenomic reads, which is a key step for metagenomics studies. In addition, we review the altered gut microbiota signatures that have been reported so far across various studies, upon which diagnostics classification models can be constructed, and the drug-induced regulation of the host microbiota can be used to control disease progression and symptoms.

Application of Metabolomics in Pediatric Asthma: Prediction, Diagnosis and Personalized Treatment

Asthma in children remains a significant public health challenge affecting 5–20% of children in Europe and is associated with increased morbidity and societal healthcare costs. The high variation in asthma incidence among countries may be attributed to differences in genetic susceptibility and environmental factors. This respiratory disorder is described as a heterogeneous syndrome of multiple clinical manifestations (phenotypes) with varying degrees of severity and airway hyper-responsiveness, which is based on patient symptoms, lung function and response to pharmacotherapy. However, an accurate diagnosis is often difficult due to diversities in clinical presentation. Therefore, identifying early diagnostic biomarkers and improving the monitoring of airway dysfunction and inflammatory through non-invasive methods are key goals in successful pediatric asthma management. Given that asthma is caused by the interaction between genes and environmental factors, an emerging approach, metabolomics—the systematic analysis of small molecules—can provide more insight into asthma pathophysiological mechanisms, enable the identification of early biomarkers and targeted personalized therapies, thus reducing disease burden and societal cost. The purpose of this review is to present evidence on the utility of metabolomics in pediatric asthma through the analysis of intermediate metabolites of biochemical pathways that involve carbohydrates, amino acids, lipids, organic acids and nucleotides and discuss their potential application in clinical practice. Also, current challenges on the integration of metabolomics in pediatric asthma management and needed next steps are critically discussed.

The gut microbiota as a target to control hyperuricemia pathogenesis: Potential mechanisms and therapeutic strategies

Hyperuricemia (HUA) is a metabolic disorder caused by abnormal uric acid (UA) metabolism, which is a complex physiological process involving multiple organs (liver, kidney, and intestine). Although UA metabolism in the liver and kidneys has been elucidated, only a few studies have focused on the process in the intestine. With our growing knowledge of the effects of gut microorganisms on health, the gut microbiota has been identified as a new target for HUA treatment. In this review, the relationship between HUA and the gut microbiota is elucidated, and anti-hyperuricemia mechanisms targeting the intestine are discussed, such as the promotion of purine and UA catabolism by the gut microbiota, increases in UA excretion by the gut microbiota and its metabolites, regulation of UA absorption or secretion in the intestinal tract by certain transporters, and the intestinal inflammatory response to the gut microbiota. Additionally, probiotics (Bifidobacteria and Lactobacilli) and prebiotics (polyphenols, peptides, and phytochemicals) with UA-lowering effects targeting the intestinal tract are summarized, providing reference and guidance for further research.

Effect of a Traditional Chinese Medicine Formula (CoTOL) on Serum Uric Acid and Intestinal Flora in Obese Hyperuricemic Mice Inoculated with Intestinal Bacteria

CoTOL is a traditional Chinese medicine (TCM) formula in clinics for treating gout and hyperuricemia, especially in obese patients with recurrent attacks. However, fewer studies have investigated how CoTOL impacts the intestinal flora in reducing uric acid. In the present, we analyze the bacteria targeted by ingredients of CoTOL and evaluate the effects of CoTOL on uric acid and intestinal flora in a mice model of obese hyperuricemia inoculated with xanthine dehydrogenase- (XOD-) producing bacteria, Streptococcus faecalis. Firstly, ingredients of herbs in CoTOL and gene target by these ingredients were retrieved from TCMID 2.0, and these genes were screened by DAVID Bioinformatics Resources 6.8, deciphered to retrieve the bacteria. Then, 3-4-week-old male C57bl/6j mice were randomly divided into 6 groups and fed with high fat diet for 8 weeks up to obesity standard. The mice were inoculated intragastrically with 5 × 10⁹ CFU Streptococcus faecalis 3 times at the 5^th, 6^th, and 7^th week and intragastrically administrated with uricase inhibitor, potassium-oxonate (PO, 250 mg/kg), to induce hyperuricemia at the 8^th week, once a day for 7 consecutive days, respectively (IB model). IB model plus CoTOL (0.4 ml/20g) and allopurinol (40 mg/kg) were administrated by gavage at the 5^th week, once a day for 4 weeks. The feces and blood in each group were sampled at the 4^th and 8^th week. With no bacteria inoculation, CoTOL, allopurinol, and blank group were treated with CoTOL and allopurinol or water, respectively. 44 species of bacteria (i.e., Enterococcus faecalis, Streptococcus, etc.) genes were targeted by 6 ingredients of 6 herbs in CoTOL. Inoculation with Streptococcus faecalis significantly caused the elevation of uric acid and the change of intestinal flora structure, whereas treatment with CoTOL significantly increased the abundance of Akkermansia and those of Bacteroides and Alloprevotella decreased. Furthermore, CoTOL exhibited a unique effect on reducing weight unobserved in allopurinol intervention. The present study, for the first time, demonstrated that CoTOL has beneficial effects on hyperuricemia and overweight, which may be attributed to regulating material metabolism and improving the structure or function of intestinal flora. Thus, CoTOL may be a promising therapy for hyperuricemia and overweight in chronic gout management and can be integrated with conventional treatments.

Chlorogenic acid supplementation ameliorates hyperuricemia, relieves renal inflammation, and modulates intestinal homeostasis

Hyperuricemia (HUA) is induced by abnormal purine metabolism and elevated serum uric acid (UA) concentrations, and it is often accompanied by inflammatory responses and intestinal disorders. This study aims to assess the protective effects of chlorogenic acid (CGA) on HUA in mice. CGA or allopurinol was given to mice with HUA induced by hypoxanthine and potassium oxonate. CGA lowered the levels of UA, blood urea nitrogen (BUN), creatinine (CR), AST, and ALT; inhibited xanthine oxidase (XOD) activity; and downregulated the mRNA expression of UA secretory proteins in HUA mice. Moreover, CGA significantly reduced serum lipopolysaccharides (LPS) levels and the mRNA expression of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, NOD-like receptor superfamily pyrin domain containing 3 (NLRP3), and caspase-1, and it inhibited the activation of the toll-like receptor 4/myeloid differentiation factor 88/nuclear factor kappa B (TLR4/MyD88/NF-κB) signaling pathway in the kidney, resulting in inflammation relief in HUA mice. In addition, CGA treatment increased the production of fecal short-chain fatty acids (SCFAs) in HUA mice. Additional investigations showed that CGA significantly lowered the mRNA expression of ileal IL-1β and IL-6, and it increased the mRNA expression of intestinal tight junction proteins (zonula occludens-1 (ZO-1) and occludin). Also, CGA increased the relative abundance of SCFA-producing bacteria, including Bacteroides, Prevotellaceae UGC-001, and Butyricimonas, and it reversed the purine metabolism and glutamate metabolism functions of gut microbiota. In conclusion, CGA may be a potential candidate for relieving the symptoms of HUA and regulating its associated inflammatory responses and intestinal homeostasis.

Gut microbiota-mediated xanthine metabolism is associated with resistance to high-fat diet-induced obesity

Resistance to high-fat diet-induced obesity (DIR) has been observed in mice fed a high-fat diet and may provide a potential approach for anti-obesity drug discovery. However, the metabolic status, gut microbiota composition, and its associations with DIR are still unclear. Here, ultraperformance liquid chromatography-tandem mass spectrometry-based urinary metabolomic and 16S rRNA gene sequencing-based fecal microbiome analyses were conducted to investigate the relationship between metabolic profile, gut microbiota composition, and body weight of C57BL/6J mice on chow or a high-fat diet for 8 weeks. PICRUSt analysis of 16S rRNA gene sequences predicted the functional metagenomes of gut bacteria. The results demonstrated that feeding a high-fat diet increased body weight and fasting blood glucose of high-fat diet-induced obesity (DIO) mice and altered the host-microbial co-metabolism and gut microbiota composition. In DIR mice, high-fat diet did not increase body weight while fasting blood glucose was increased significantly compared to chow fed mice. In DIR mice, the urinary metabolic pattern was shifted to a distinct direction compared to DIO mice, which was mainly contributed by xanthine. Moreover, high-fat diet caused gut microbiota dysbiosis in both DIO and DIR mice, but in DIR mice, the abundance of Bifidobacteriaceae, Roseburia, and Escherichia was not affected compared to mice fed a chow diet, which played an important role in the pathway coverage of FormylTHF biosynthesis I. Meanwhile, xanthine and pathway coverage of FormylTHF biosynthesis I showed significant positive correlations with mouse body weight. These findings suggest that gut microbiota-mediated xanthine metabolism correlates with resistance to high-fat DIO.

Kidney Function Indicators Predict Adverse Outcomes of COVID-19

Background

The coronavirus disease 2019 (COVID-19) is a recently emerged respiratory infectious disease with kidney injury as a part of the clinical complications. However, the dynamic change of kidney function and its association with COVID-19 prognosis are largely unknown.

Methods

In this multicenter retrospective cohort study, we analyzed clinical characteristics, medical history, laboratory tests, and treatment data of 12,413 COVID-19 patients. The patient cohort was stratified according to the severity of the outcome into three groups: non-severe, severe, and death.

Findings

The prevalence of elevated blood urea nitrogen (BUN), elevated serum creatinine (Scr), and decreased blood uric acid (BUA) at admission was 6.29%, 5.22%, and 11.66%, respectively. The trajectories showed the elevation in BUN and Scr levels, as well as a reduction in BUA level for 28 days after admission in death cases. Increased all-cause mortality risk was associated with elevated baseline levels of BUN and Scr and decreased levels of BUA.

Conclusions

The dynamic changes of the three kidney function markers were associated with different severity and poor prognosis of COVID-19 patients. BUN showed a close association with and high potential for predicting adverse outcomes in COVID-19 patients for severity stratification and triage.

Funding

This study was supported by grants from the National Key R&D Program of China (2016YFF0101504), the National Science Foundation of China (81630011, 81970364, 81970070, 81970011, 81870171, and 81700356), the Major Research Plan of the National Natural Science Foundation of China (91639304), the Hubei Science and Technology Support Project (2019BFC582, 2018BEC473, and 2017BEC001), and the Medical Flight Plan of Wuhan University.

Gut Bacterial Species Distinctively Impact Host Purine Metabolites during Aging in Drosophila

Gut microbiota impacts the host metabolome and affects its health span. How bacterial species in the gut influence age-dependent metabolic alteration has not been elucidated. Here we show in Drosophila melanogaster that allantoin, an end product of purine metabolism, is increased during aging in a microbiota-dependent manner. Allantoin levels are low in young flies but are commonly elevated upon lifespan-shortening dietary manipulations such as high-purine, high-sugar, or high-yeast feeding. Removing Acetobacter persici in the Drosophila microbiome attenuated age-dependent allantoin increase. Mono-association with A. persici, but not with Lactobacillus plantarum, increased allantoin in aged flies. A. persici increased allantoin via activation of innate immune signaling IMD pathway in the renal tubules. On the other hand, analysis of bacteria-conditioned diets revealed that L. plantarum can decrease allantoin by reducing purines in the diet. These data together demonstrate species-specific regulations of host purine levels by the gut microbiome.