Aberrant gut microbiota alters host metabolome and impacts renal failure in humans and rodents

Machine-learning assisted discovery unveils novel interplay between gut microbiota and host metabolic disturbance in diabetic kidney disease

Diabetic kidney disease (DKD) is a serious healthcare dilemma. Nonetheless, the interplay between the functional capacity of gut microbiota and their host remains elusive for DKD. This study aims to elucidate the functional capability of gut microbiota to affect kidney function of DKD patients. A total of 990 subjects were enrolled consisting of a control group (n = 455), a type 2 diabetes mellitus group (DM, n = 204), a DKD group (n = 182) and a chronic kidney disease group (CKD, n = 149). Full-length sequencing of 16S rRNA genes from stool DNA was conducted. Three findings are pinpointed. Firstly, new types of microbiota biomarkers have been created using a machine-learning (ML) method, namely relative abundance of a microbe, presence or absence of a microbe, and the hierarchy ratio between two different taxonomies. Four different panels of features were selected to be analyzed: (i) DM vs. Control, (ii) DKD vs. DM, (iii) DKD vs. CKD, and (iv) CKD vs. Control. These had accuracy rates between 0.72 and 0.78 and areas under curve between 0.79 and 0.86. Secondly, 13 gut microbiota biomarkers, which are strongly correlated with anthropometric, metabolic and/or renal indexes, concomitantly identified by the ML algorithm and the differential abundance method were highly discriminatory. Finally, the predicted functional capability of a DKD-specific biomarker, Gemmiger spp. is enriched in carbohydrate metabolism and branched-chain amino acid (BCAA) biosynthesis. Coincidentally, the circulating levels of various BCAAs (L-valine, L-leucine and L-isoleucine) and their precursor, L-glutamate, are significantly increased in DM and DKD patients, which suggests that, when hyperglycemia is present, there has been alterations in various interconnected pathways associated with glycolysis, pyruvate fermentation and BCAA biosynthesis. Our findings demonstrate that there is a link involving the gut-kidney axis in DKD patients. Furthermore, our findings highlight specific gut bacteria that can acts as useful biomarkers; these could have mechanistic and diagnostic implications.

Characterization of gut dysbiosis and intestinal barrier dysfunction in patients with metabolic dysfunction-associated steatotic liver disease and chronic kidney disease: a comparative study

The mechanistic role of gut microbiota in metabolic dysfunction-associated steatotic liver disease (MASLD) and chronic kidney disease (CKD) is increasingly recognized. Despite their close association, comparative data regarding gut dysbiosis in these disorders are limited. This study included 22 healthy controls and 180 patients (90 MASLD, 60 CKD, and 30 both diseases with sex- and age-matched). Fecal bacterial 16 S ribosomal RNA sequencing and butyryl-CoA: acetate CoA transferase (BCoAT) gene expression were analyzed. Plasma intestinal fatty acid binding protein (I-FABP), representing intestinal barrier dysfunction, was assessed using the ELISA method. Our data showed that alpha and beta diversities of gut microbiota differed between MASLD and healthy controls. However, only beta diversities were different between CKD and healthy individuals. The MASLD and CKD groups displayed fewer SCFA-producing genera, particularly Bifidobacterium, than healthy controls. Fecal BCoAT levels were inversely correlated with eGFR and I-FABP levels. Patients with CKD had significantly enriched pathogenic bacteria, reduced BCoAT, and increased I-FABP levels versus MASLD. Combining significant bacterial genera discriminated MASLD from CKD with high diagnostic accuracy (AUC of 0.90). Among patients with both diseases, gut microbial alterations showed mixed characteristics of MASLD and CKD. These data highlighted the shared and distinct gut dysbiosis and related biomarkers, which could provide a better understanding of MASLD and CKD pathogenesis.

DMoVGPE: predicting gut microbial associated metabolites profiles with deep mixture of variational Gaussian Process experts

BACKGROUND

Understanding the metabolic activities of the gut microbiome is vital for deciphering its impact on human health. While direct measurement of these metabolites through metabolomics is effective, it is often expensive and time-consuming. In contrast, microbial composition data obtained through sequencing is more accessible, making it a promising resource for predicting metabolite profiles. However, current computational models frequently face challenges related to limited prediction accuracy, generalizability, and interpretability.

METHOD

Here, we present the Deep Mixture of Variational Gaussian Process Experts (DMoVGPE) model, designed to overcome these issues. DMoVGPE utilizes a dynamic gating mechanism, implemented through a neural network with fully connected layers and dropout for regularization, to select the most relevant Gaussian Process experts. During training, the gating network refines expert selection, dynamically adjusting their contribution based on the input features. The model also incorporates an Automatic Relevance Determination (ARD) mechanism, which assigns relevance scores to microbial features by evaluating their predictive power. Features linked to metabolite profiles are given smaller length scales to increase their influence, while irrelevant features are down-weighted through larger length scales, improving both prediction accuracy and interpretability.

CONCLUSIONS

Through extensive evaluations on various datasets, DMoVGPE consistently achieves higher prediction performance than existing models. Furthermore, our model reveals significant associations between specific microbial taxa and metabolites, aligning well with findings from existing studies. These results highlight DMoVGPE's potential to provide accurate predictions and to uncover biologically meaningful relationships, paving the way for its application in disease research and personalized healthcare strategies.

Dietary index for gut microbiota, a novel protective factor for the prevalence of chronic kidney diseases in the adults: insight from NHANES 2007-2018

Introduction

This study explore the association between the dietary index for gut microbiota (DI-GM) and the prevalence of chronic kidney disease (CKD).

Method

A cross-sectional study of participants aged ≥20 years using the data drawn from NHANES (2007-2018). DI-GM is comprised 14 dietary components (10 beneficial and 4 unfavorable). CKD diagnosis based on urine albumin-to-creatinine ratio (uACR) and estimated glomerular filtration rate (eGFR). Logistic regression models were employed to evaluate the relationship between DI-GM and CKD while controlling for various covariates. Additionally, a spline smooth analysis was performed. Subgroup and interaction analyses were conducted to investigate whether any factors modified this relationship.

Results

A total of 28,843 participants were eligible for the study, of whom 5,461 were diagnosed with CKD, while 23,382 were not. Patients with CKD exhibited significantly lower DI-GM scores compared to healthy individuals. A negative association between DI-GM and the prevalence of CKD was observed across all models, with the relationship being more pronounced in individuals with DI-GM scores greater than 5 compared to those with scores ≤3. Beneficial components, such as dietary fiber, whole grains, and coffee, were identified as protective factors. Moreover, sex make an effect on this relationship, with stronger effects noted in women.

Conclusion

Higher DI-GM scores correlate with reduced CKD prevalence, and the effect appears to be more pronounced in women than in men. These findings suggest that enhancing gut health through diet may serve as a viable strategy for the prevention and management of CKD, with particular attention to sex-based differences in prevention.

Effect of L. plantarum on Caries Prevention and the Oral-Gut Microbiome In Vivo

While Lactiplantibacillus plantarum has shown promise against cariogenic pathogens, its in vivo effects on caries prevention remain unexplored. This study used a rat model to investigate the effect of L. plantarum early-life oral inoculation on oral and gut microbiomes, host immune responses, and serum metabolites. Forty 14-day Sprague-Dawley rat pups were randomly allocated into 5 groups: (1) blank control, (2) L. plantarum colonization alone, (3) Streptococcus mutans and Candida albicans co-colonization, (4) L. plantarum precolonization before S. mutans and C. albicans exposure, and (5) 2-wk treatment of L. plantarum after S. mutans and C. albicans exposure. Dynamic colonization of L. plantarum, S. mutans, and C. albicans in saliva and plaque was assessed using a culture-dependent method. Saliva, plaque, and fecal microbiomes were assessed using 16S ribosomal RNA gene sequencing. Caries scoring was performed using Keyes' scoring system and microcomputed tomography. Serum metabolite and immune markers were assessed through liquid chromatography tandem mass spectrometry untargeted metabolomics and multiplex immune profiling. We found that 3-d L. plantarum inoculation established stable L. plantarum colonization in the oral cavity of young rats. Inoculation timing of L. plantarum was critical for caries prevention. L. plantarum precolonization significantly reduced caries lesions compared with the S. mutans and C. albicans group, whereas 2 wk of postexposure treatment did not demonstrate a protective effect. L. plantarum precolonization led to distinct microbial shifts in saliva, plaque, and gut microbiomes, with an increased abundance of beneficial bacteria, such as Streptococcus azizii, Bifidobacterium animalis, Faecalibaculum rodentium, and Allobaculum stercoricanis, and a decrease in S. mutans. L. plantarum preinoculation also influenced metabolic profiles, with 1 metabolite upregulated and 24 downregulated, although immune marker differences were minimal. In conclusion, L. plantarum oral colonization before host exposure to oral cariogenic pathogens effectively reduced caries and modulated the profile of oral and gut microbiomes and serum metabolic profile.

Exploring the effect of soybean fermentation broth (S-FB) on gut microbes of lipopolysaccharide (LPS)-infected loach (Misgurnus anguillicaudatus) using 16S rRNA sequencing

The fermentation products of soybean are rich in beneficial bacteria, which play Shenghui Chu a significant role in maintaining the balance of intestinal microbiota and improving intestinal health. To investigate the immunomodulatory effects of soybean fermentation broth (S-FB) on loach (Misgurnus anguillicaudatus) with lipopolysaccharide (LPS)-induced enteritis, 16S rDNA high-throughput sequencing technology was employed to analyze the composition and structure of intestinal microbiota in two groups: the LPS-treated group (fed with soybean broth) and the control group (normal feeding conditions). The results revealed that the relative abundance of beneficial bacteria, such as Lactobacillus and Muribaculaceae, significantly increased in the treatment group, while the relative abundance of harmful bacteria, including Aeromonas and Shewanella, decreased. These findings suggest that soybean fermentation broth can repair intestinal damage and maintain intestinal health by enhancing the abundance of beneficial bacteria and reducing the pathogenic effects of harmful bacteria on the host. Functional prediction studies of microbial communities also showed that treatment groups primarily affected metabolic and genetic information processing. The research results analyzed the changes in the structure and distribution of intestinal microflora in different groups of loach, providing new insights into the possible role of soybean fermentation liquid in intestinal inflammation.

Disrupted gut microbiota promotes the progression of chronic kidney disease in 5/6 nephrectomy mice by Bacillus pumilus gavage

Background

Our previous study identified differences in the gut microbiota between patients with chronic kidney disease (CKD) and healthy individuals. We observed that antibiotic-treated mice exhibited symptoms similar to those of patients with CKD after receiving a gut microbiota transplant from patients with CKD. Bacillus pumilus (B. pumilus), an alien microorganism to both human and mouse gut microbiota, possesses antibiotic properties that can alter the microbial community structure. Therefore, this study aimed to explore how changes in the gut microbiota structure induced by the oral gavage of B. pumilus affect the progression of CKD. We sought to identify the gut microbes and metabolic pathways associated with CKD to lay the groundwork for future clinical probiotic applications in patients with CKD.

Methods

We constructed sham-operated and 5/6 nephrectomy mice as the sham control (SC) and CKD models, respectively. CKD models were divided into a control group (CG) and an intervention group (IG). After 16 weeks of normal feeding, the IG were treated with B. pumilus by oral gavage, while SC and CG were treated with PBS once daily, 5 days per week, for 7 weeks. Fecal samples were collected for 16s rRNA sequencing and metabolomic analysis, kidneys were harvested for histological examination, and the colon was used for RT-PCR analysis.

Results

B. pumilus intervention exacerbated gut microbial homeostasis in CKD mice and increased serum creatinine and urea nitrogen levels, further aggravating kidney damage. 16s rRNA and metabolomic analysis revealed that Parvibacter and Enterorhabdus were probiotics related to kidney function, while Odoribacter was associated with kidney injury. Metabolomic analysis showed that glycerophospholipid and lysine metabolism were upregulated in CKD model mice, correlating with kidney damage.

Conclusion

This study shows that changes in the gut microbiota can affect the kidneys through gut metabolism, confirming that the lack of probiotics and the proliferation of harmful bacteria leading to gut microbiota dysbiosis are drivers of CKD progression. Our findings provide a basis for clinical interventions using gut microbes and offer a reference for targeted probiotic therapy.

Native potential probiotics and postbiotics improve the gut-kidney axis by the modulation of autophagy signaling pathway

The gut-kidney axis is the bidirectional relationship between the gut microbiota and the kidney function. Chronic inflammatory responses can impair kidney function and probiotics and postbiotics agents can have positive effects on gut health and kidney function by modulating inflammation through affecting autophagy signaling pathway. The aim of the current study was to evaluate the properties of our probiotic and postbiotics to improve kidney health by focusing the autophagy signaling pathway. The probiotic and postbiotics of four Lactobacillus and two Bifidobacterium strains were selected. Dextran sulfate sodium induced colitis in mice, and probiotics and postbiotics treatments were accomplished in animal experiment. A qPCR assay was performed to assess the gene expression involved in the autophagy process in the kidney. In contrast to the dextran sulfate sodium group, both the probiotic and postbiotics cocktails exhibited the capacity to inhibit colitis-associated indicators. Of note, the postbiotics cocktails demonstrated a greater efficacy in preventing colitis-related indicators and also it could display a more pronounced effect in upregulating autophagy-related genes. Our native potential probiotics and postbiotics can be able to reduce gut inflammation and cope with kidney inflammation by triggering autophagy signaling pathway through the considerable impact on gut-organ axis. There is an encouraging concept about the anti-inflammatory effects of our probiotics and postbiotics cocktails with least side effects as a supplementary treatment not only in the gut, but also in the other organs particularly kidneys.

Involvement of gut microbiota in chlorpyrifos-induced subchronic toxicity in mice

Chlorpyrifos (CPF) is one of the most widely used organophosphorus pesticides all over the world. Unfortunately, long-term exposure to CPF may cause considerable toxicity to organisms. Some evidence suggests that the intestinal microbial community may be involved in regulating the toxicity of CPF. In this study, we explored if the intestinal microbial community is involved in regulating the toxicity of CPF. Adult mice were continuously exposed to CPF (4 mg/kg body weight /day) for 10 weeks with or without a 2-week pretreatment of antibiotics to change the ecological structure of intestinal microorganisms in advance. Pathological changes in the liver and kidneys were examined and the biochemical parameters in serum for liver and kidney functions were detected, and changes in the intestinal microbial community of the mice were measured. The results showed that subchronic exposure to low-dose CPF caused an ecological imbalance in the intestinal flora and caused pathological damage to the liver and kidneys. Serum biochemical indicators for liver function such as alanine aminotransferase and total bile acids contents and renal biochemical indicators such as urea nitrogen and creatinine were disrupted. Changes in intestinal microbial community structure by using antibiotics in advance can effectively alleviate the pathological and functional damage to the liver and kidneys caused by CPF exposure. Further analysis showed that intestinal microorganisms such as Saccharibacteria (TM7), Odoribacter, Enterococcus and AF12 genera may be involved in managing the toxicity of CPF. Together, our results indicated that long-term low-dose CPF exposure could induce hepatotoxicity and nephrotoxicity, and liver and kidney damage may be mitigated by altering the ecology of intestinal microorganisms.

Decrease in Escherichia-Shigella in the gut microbiota of ESKD patients undergoing maintenance hemodialysis

BACKGROUND

Gut dysbiosis is thought to be involved in the pathogenesis and progression of chronic kidney disease and end-stage kidney disease (ESKD). However, differences in the composition and function of gut microbiota in hemodialysis patients are not consistently concluded.

METHODS

A total of 20 patients receiving maintenance hemodialysis (MHD) treatment at the Blood Purification Center of Bethune International Peace Hospital from March 2021 to December 2022 were included based on the inclusion criteria. Additionally, 20 healthy volunteers matched for age, gender, and body mass index were recruited from the Health Examination Center as the healthy control (HC) group. The structure of the gut microbiota community in the study subjects was analyzed using second-generation high-throughput sequencing technology based on 16S rRNA and amplicon sequence variants (ASV) analysis.

RESULTS

There were significant differences in gut microbial communities between the two groups. At the genus level, significant differences were found in 19 genera. Among them, Escherichia-Shigella, Lachnospira, Parasutterella, [Ruminococcus]-torques-group, Butyricicoccus, and Streptococcus were significantly decreased, while Phascolarctobacterium, Ruminococcaceae-UBA1819, Erysipelotrichaceae-UCG-003, Flavonifractor, and Erysipelatoclostridium were significantly increased in MHD patients. In particular, the abnormal decrease in the abundance of p-Proteobacteria.c-Gammaproteobacteria.o-Enterobacterales.f-Enterobacteriaceae.g-Escherichia-Shigella might be a significant characteristic of gut microbiota in MHD patients.

CONCLUSION

The decreased abundance of Escherichia-Shigella is a signature gut microbiota alteration in patients with ESKD undergoing MHD, and Escherichia-Shigella may represent a key bacterial group warranting exploration in the field of hemodialysis. The dysbiosis of gut microbiota holds promise as a therapeutic target and biomarker for the diagnosis and treatment of MHD.

Gut microbiome alterations precede graft rejection in kidney transplantation patients

Kidney transplantation (KT) is the best treatment for end-stage kidney disease, with graft survival critically affected by the recipient's immune response. The role of the gut microbiome in modulating this immune response remains underexplored. Our study investigates how microbiome alterations might associate with allograft rejection by analyzing the gut microbiome using 16S rRNA gene amplicon sequencing of a multicenter prospective study involving 562 samples from 245 individuals of which 217 received KT. Overall, gut microbiome composition showed gradual recovery post-KT, mirroring CKD-to-health transition as indicated by an increase of Shannon diversity. Prior to graft rejection, we observed a decrease in microbial diversity and SCFA-producing taxa. Functional analysis highlighted a decreased potential for SCFA production in patients preceding the rejection event, validated by quantitative PCR for the production potential of propionate and butyrate. Post-rejection analysis revealed normalization of these microbiome features. Comparison to published microbiome signatures from CKD patients demonstrated a partial overlap of the microbiome alterations preceding graft rejection with the alterations typically found in CKD. Our findings suggest that alterations in gut microbiome composition and function may precede and influence KT rejection, suggesting potential implications as biomarkers or for early therapeutic microbiome-targeting interventions.

Investigating the role of gut microbiota in diabetic nephropathy through plasma proteome mediated analysis

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease and poses significant threats to individuals with diabetes. The concept of gut-kidney axis has gained increasing attention in recent years and the in the occurrence and development of DN, alterations in the gut microbiota also plays a crucial and indispensable role. However, the specific causal relationships between various gut microbial communities and DN, as well as the underlying molecular mechanisms, remains unclear. This study utilized data from genome-wide association studies. After screening for qualified instrumental variables, mendelian randomization causal analyses were performed by inverse variance weighting, MR-Egger, weighted median, weighted mode and MR-RAPS methods. Additionally, sensitivity analyses such as heterogeneity, multiplicity, and the direction of the causal effect were carried out to ensure that the results were robust. After identifying significant gut microbiota, protein-proteomics mediation analysis was conducted on potential 3282 plasma proteins to determine those with mediating effects. Finally, Reactome enrichment analysis was performed to ascertain metabolic or signaling pathways with mediating effects. Mendelian randomization analysis indicated associations between 21 gut microbiota and DN. After adjusting significance levels, Catenibacterium and Parasutterella were found to have causal effects on the onset of DN. Subsequently, we identified 22 plasma proteins with mediating effects, along with 27 metabolic or signaling pathways including activated propionic acid metabolism. Increased in the abundance of Catenibacterium and Parasutterella intestinal bacteria are causative factors for DN. More importantly, the underlying mechanism by which the increased abundance of Catenibacterium and Parasutterella intestinal bacteria lead to DN were revealed, providing a blueprint for the involvement of gut-kidney axis in the pathogenesis of DN and paving the way for future studies.

Structural and functional changes in the oral microbiome of patients with craniofacial microsomia

Craniofacial microsomia (CFM) is the second most common congenital craniofacial deformity, presenting diverse clinical manifestations and treatments that may influence oral bacteria dysbiosis (OBD). However, research linking CFM to OBD is limited. Saliva samples were collected from 20 patients with CFM and 24 controls. We compared oral microflora and gene function using 16 S ribosomal RNA sequencing and metagenomics. We also evaluated the correlation between CFM clinical phenotypes and microbiota community structure. Patients with CFM demonstrated greater richness and evenness in their oral microflora. The dominant genera included several pathogenic species, such as Actinomyces, Fusobacterium, and Prevotella. Notably, the severity of CFM correlated positively with the abundance of Neisseria and Porphyromonas. Upregulated pathways were primarily linked to biotin and amino acid metabolism, such as Tryptophan metabolism and Lysine degradation, and further underscored the need for focused oral health interventions in this population. This study is the first to indicate that CFM patients exhibit unique oral bacterial dysbiosis, marked by a higher presence of opportunistic pathogens and increased pathways related to oral and systemic health. These findings highlight the importance of monitoring oral health in patients with CFM.

Potential Trimethylamine (TMA)-Producing Bacteria in patients with chronic kidney disease undergoing hemodialysis

INTRODUCTION

Trimethylamine (TMA), produced by gut microbiota, is the precursor of trimethylamine-N-oxide (TMAO), a uremic toxin that accumulates in patients with chronic kidney disease (CKD). Elevated TMAO plasma levels are associated with cardiovascular complications and CKD progression.

OBJECTIVE

To evaluate the association between gut microbiota composition and TMAO plasma levels in CKD patients undergoing hemodialysis (HD).

METHODS

This is a cross-sectional study with 25 patients evaluated (60% female, 53 (18) years, body mass index (BMI) 25.8 (6.75) Kg/m2). They were divided into two groups according to their TMAO plasma levels: normal (≤ 7.4 μM) and high (> 7.4 μM). Uremic toxins such as indoxyl sulfate (IS), p-cresyl sulfate (pCS), and indol acetic acid (IAA) were measured with RP-HPLC, and TMAO plasma levels were quantified using LC-MS/MS. Fecal DNA was extracted with a commercial kit, PCR amplified the V4 region of the 16S rRNA gene, and short-read sequencing was performed on the Illumina platform. Dietary intake, anthropometric measurements, and inflammation markers were also evaluated. Nrf2, NF-κB, IL-1β, and NLRP3 mRNA expressions were measured from peripheral blood mononuclear cells (PBMC) using quantitative real-time polymerase chain reaction (qPCR).

RESULTS

There were significant positive correlations between TMAO and plasma levels of pCS, NLPR3 inflammasome mRNA expression, serum phosphorus levels, and negative correlations with dietary lipid intake. The group with TMAO > 7.4 μM showed an increase in the microbiome abundance of Saccharibacteria (genus incertae sedis), Colidextribacter, Dorea, and Staphylococci genera, and a decrease in abundance in the genera Lachnospira, Lactobacilli, and Victivallis. TMAO plasma level was positively correlated with the abundance of bacteria of the genera Colidextribacter and Helicobacter and was negatively correlated with Sphingomanos, Lachnospira, Streptomyces, and Bacillus genera.

CONCLUSION

Saccharibacteria (genus incertae sedis), Colidextribacter, Dorea, and Staphylococci genera showed higher abundance in patients with high TMAO levels. In addition, we observed that elevated plasma TMAO levels are associated with inflammation markers, dietary lipid intake, and serum phosphorus levels in patients undergoing HD.

Gut-X axis

Recent advances in understanding the modulatory functions of gut and gut microbiota on human diseases facilitated our focused attention on the contribution of the gut to the pathophysiological alterations of many extraintestinal organs, including the liver, heart, brain, lungs, kidneys, bone, skin, reproductive, and endocrine systems. In this review, we applied the "gut-X axis" concept to describe the linkages between the gut and other organs and discussed the latest findings related to the "gut-X axis," including the underlying modulatory mechanisms and potential clinical intervention strategies.

Exploring the mechanism of Paotianxiong polysaccharide in the treatment of chronic kidney disease combining metabolomics and microbiomics technologies

A close relationship between the pathogenesis of chronic kidney disease (CKD) and abnormalities in the gut-kidney axis. Paotianxiong polysaccharides (PTXP) that have demonstrated therapeutic effects on CKD. However, the specific mechanism by which PTXP ameliorates CKD through the gut-kidney axis remains to be explored. In this study, the microbiomes and metabolomics were combined to investigate the impact of PTXP on intestinal flora structure and metabolism, further unveiling the relationship through correlation analysis. The results showed that PTXP intervention significantly modulated renal function abnormalities in CKD rats and significantly modulates gut microbial disorders, evidenced by an increased abundance of Lactobacillus murinus, Bacteroides fragilis, and a decreased abundance of Bifidobacterium pseudolongum. Furthermore, PTXP reversed the changes in intestinal metabolites, such as linoleic acid and docosahexaenoic acid, induced by CKD and identified unsaturated fatty acid metabolism as a key metabolic pathway. Correlation analyses also revealed associations among gut microorganisms, metabolites, and renal function indexes, confirming that PTXP alleviated CKD through the gut-kidney axis. Moreover, the above conclusions were verified by fecal bacteria transplantation experiments. These findings provide insights into the mechanism of PTXP for the treatment of CKD and provide new targets for the treatment of CKD.

The gut-kidney axis is regulated by astragaloside IV to inhibit cyclosporine A-induced nephrotoxicity

Introduction

Chronic nephrotoxicity caused by CNIs (CICN) manifests clinically as chronic kidney disease (CKD). Astragaloside IV (AS-IV) plays a certain role in the treatment of CKD. This study aimed to verify the ameliorative effects of AS-IV on CICN and further explore the mechanisms underlying the modulation of the "gut-transcriptome-metabolome coexpression network" by AS-IV within the context of the "gut-kidney axis" to improve CICN.

Methods

Five groups of 40 mice were studied: a normal group (N, olive oil), a model group (M, CsA, 30 mg kg--1 d-1), a low-dose AS-IV group (CsA + AS-IV, 30 mg kg-1 d-1 + 10 mg kg-1 d-1), a high-dose AS-IV group (CsA + AS-IV, 30 mg kg-1 d-1 + 20 mg kg-1 d-1), and a valsartan group (CsA + Val, 30 mg kg-1 d-1 + 10 mg kg-1 d-1). The gut microbiota, renal transcriptome, and urine metabolome were separately detected to construct a gut-transcriptome-metabolome coexpression network. The target species, target genes, and target metabolites of AS-IV were evaluated.

Results

CsA led to increased proteinuria and a deterioration of kidney function, accompanied by increased inflammation and oxidative stress, whereas AS-IV improved kidney damage. AS-IV inhibited intestinal permeability and disrupted the microbiota structure, increasing the abundance of Lactobacillus reuteri, Bifidobacterium animalis, Ignatzschineria indica, and Blautia glucerasea. Six coexpression pathways related to transcription and metabolism, including the citrate cycle, ascorbate and aldarate metabolism, proximal tubule bicarbonate reclamation, glycolysis/gluconeogenesis, ferroptosis, and drug metabolism-cytochrome P450, were identified. Seven target metabolites of AS-IV were identified in the 6 pathways, including UDP-D-galacturonic acid, 2-phenylethanol glucuronide, dehydroascorbic acid, isopentenyl pyrophosphate, alpha-D-glucose, 3-carboxy-1-hydroxypropylthiamine diphosphate and citalopram aldehyde. Five target genes of AS-IV, Ugt1a2, Ugt1a9, Ugt1a5, Pck1, and Slc7a11, were also identified and predicted by NONMMUT144584.1, MSTRG.30357.1 and ENSMUST00000174821. Lactobacillus reuteri was highly correlated with renal function and the target genes and metabolites of AS-IV. The target genes and metabolites of AS-IV were further validated. AS-IV inhibited intestinal-derived urinary toxins and improved renal tissue apoptosis, lipid accumulation, collagen deposition, and mitochondrial damage.

Conclusion

AS-IV improved CICN through the coexpression of the gut-transcriptome-metabolome network. The six pathways related to energy metabolism driven by L. reuteri, including the citrate cycle, ascorbate and alderate metabolism, proximal tube bicarbonate metabolism, glycolysis/gluconeogenesis, ferroptosis, drug metabolism-cytochrome P450, are important mechanisms.

Protein-bound uremic toxins as therapeutic targets for cardiovascular, kidney, and metabolic disorders

Cardiovascular-kidney-metabolic (CKM) syndrome is a systemic clinical condition characterized by pathological and physiological interactions among metabolic abnormalities, chronic kidney disease, and cardiovascular diseases, leading to multi-organ dysfunction and a higher incidence of cardiovascular endpoints. Traditional approaches to managing CKM syndrome risk are inadequate in these patients, necessitating strategies targeting specific CKM syndrome risk factors. Increasing evidence suggests that addressing uremic toxins and/or pathways induced by uremic toxins may reduce CKM syndrome risk and treat the disease. This review explores the interactions among heart, kidney, and metabolic pathways in the context of uremic toxins and underscores the significant role of uremic toxins as potential therapeutic targets in the pathophysiology of these diseases. Strategies aimed at regulating these uremic toxins offer potential avenues for reversing and managing CKM syndrome, providing new insights for its clinical diagnosis and treatment.

The mechanism of enterogenous toxin methylmalonic acid aggravating calcium-phosphorus metabolic disorder in uremic rats by regulating the Wnt/β-catenin pathway

BACKGROUND

Uremia (UR) is caused by increased UR-related toxins in the bloodstream. We explored the mechanism of enterogenous toxin methylmalonic acid (MMA) in calcium-phosphorus metabolic disorder in UR rats via the Wnt/β-catenin pathway.

METHODS

The UR rat model was established by 5/6 nephrectomy. The fecal bacteria of UR rats were transplanted into Sham rats. Sham rats were injected with exogenous MMA or Salinomycin (SAL). Pathological changes in renal/colon tissues were analyzed. MMA concentration, levels of renal function indicators, serum inflammatory factors, Ca2+/P3+, and parathyroid hormone, intestinal flora structure, fecal metabolic profile, intestinal permeability, and glomerular filtration rate (GFR) were assessed. Additionally, rat glomerular podocytes were cultured, with cell viability and apoptosis measured.

RESULTS

Intestinal flora richness and diversity in UR rats were decreased, along with unbalanced flora structure. Among the screened 133 secondary differential metabolites, the MMA concentration rose, showing the most significant difference. UR rat fecal transplantation caused elevated MMA concentration in the serum and renal tissues of Sham rats. The intestinal flora metabolite MMA or exogenous MMA promoted intestinal barrier impairment, increased intestinal permeability, induced glomerular podocyte loss, and reduced GFR, causing calcium-phosphorus metabolic disorder. The intestinal flora metabolite MMA or exogenous MMA induced inflammatory responses and facilitated glomerular podocyte apoptosis by activating the Wnt/β-catenin pathway, which could be counteracted by repressing the Wnt/β-catenin pathway.

CONCLUSIONS

Enterogenous toxin MMA impelled intestinal barrier impairment in UR rats, enhanced intestinal permeability, and activated the Wnt/β-catenin pathway to induce glomerular podocyte loss and reduce GFR, thus aggravating calcium-phosphorus metabolic disorder.

Fucoidan Oligosaccharide Supplementation Relieved Kidney Injury and Modulated Intestinal Homeostasis in D-Galactose-Exposed Rats

Background/Objectives: A fucoidan oligosaccharide (FOS), a potent compound derived from algae, is known for its diverse biological activities, including prebiotic activity, anticancer activity, and antioxidative properties, and has demonstrated supportive therapeutic effects in treating kidney ailments. This study was conducted to explore the protective influence of FOS on kidney damage due to aging induced by D-galactose in Sprague Dawley (SD) rats. Methods: The low-dose FOS group was administered FOS (100 mg/kg) by gavage, and the high-FOS group received FOS (200 mg/kg) by gavage. Results: The findings showed that FOS could effectively mitigate kidney damage and improve the pathological condition of kidney tissues caused by D-gal and enhance kidney function. Intervention with FOS significantly reduced serum creatinine, serum uric acid, and serum urea nitrogen levels, compared to the model group. The protective mechanism of FOS on D-gal-induced kidney injury may be to inhibit oxidative stress and improve impaired mitochondrial function by downregulating the AMPK/ULK1 signaling pathway. FOS could also modulate the expression of mitochondrial autophagy-related proteins (Beclin-1, P62, and LC3II/LC3I), thereby mitigate D-gal-induced excessive mitophagy in the kidney. Furthermore, FOS may protect against kidney injury by preserving intestinal homeostasis. FOS decreased serum lipopolysaccharide levels and enhanced intestinal mucosal barrier function. FOS upregulated the abundances of Bacteroidota, Muribaculaceae, and Lactobacillus, while it decreased the abundances of Firmicutes, NK4A136_group, and Lachnospiraceae_NK4A136_group. FOS supplementation modulated gut microbiota composition, increasing beneficial bacteria and reducing detrimental ones, potentially contributing to improved kidney function. Conclusions: FOS may safeguard against renal injury in D-gal-exposed rats by inhibiting kidney excessive mitophagy, preserving mitochondrial function, and regulating intestinal homeostasis.

High interindividual variability of indoxyl sulfate production identified by an oral tryptophan challenge test

Indoxyl sulfate (IS) has been implicated in the pathogenesis of cardiovascular diseases. IS is converted from indole, a metabolite of dietary tryptophan through the action of gut microbial tryptophanase, by two hepatic enzymes: CYP2E1 and SULT1A1. We hypothesized that the effect of tryptophan intake on IS production might differ from person to person. We enrolled 72 healthy persons (33 ± 7 years; 54.2% women) to undergo an oral tryptophan challenge test (OTCT), in which 7 blood samples were collected at 0, 4, 8, 12, 24, 36, and 48 h following oral administration of L-tryptophan 2000 mg. We observed high interindividual variability of IS production in the response to an OTCT. Twenty-four subjects in the lowest tertile of the baseline-adjusted area under the curve of IS were defined as low-IS producers, whereas 24 subjects in the highest tertile were defined as high-IS producers. There was no significant difference in baseline characteristics or CYP2E1 and SULT1A1-SNP genotyping distributions between the two IS-producing phenotypes. However, distinct differences in gut microbial composition were identified. In addition, the abundance of tryptophanase was significantly higher in the high-IS producers than in the low-IS producers (P = 0.01). The OTCT may serve as personalized dietary guidance. High-IS producers are more likely to be at greater risk of cardiovascular diseases and may benefit from consuming foods low in tryptophan. Potential clinical applications of the OTCT in precision nutrition warrant further investigation.

Investigating the biological significance of the TCM principle "promoting urination to regulate bowel movements" through the influence of the intestinal microbiota and their metabolites on the renal-intestinal axis

Treatment methods in traditional Chinese medicine (TCM) are foundational to their theoretical, methodological, formulaic, and pharmacological systems, significantly contributing to syndrome differentiation and therapy. The principle of "promoting urination to regulate bowel movements" is a common therapeutic approach in TCM. The core concept is "promoting the dispersion and drainage of water dampness, regulating urination to relieve diarrhea," yet its scientific underpinning remains unclear. Modern medical treatment for watery diarrhea primarily focuses on electrolyte replenishment, as diuretics may lead to dehydration and other side effects. Some reports suggest that this TCM approach lacks scientific validity. Microecology, an area associated with the origins of TCM, is closely related to the development, diagnosis, and treatment of diarrhea. The renal-intestinal axis offers a molecular biological basis for examining associated pathological mechanisms, advancing therapeutic targets such as "treating the intestine to address kidney issues" and highlighting the interactions within the "renal-intestinal microbiota-liquid metabolism" framework, thus providing an endogenous mechanism to support "treating the intestine through the kidney." An increasing number of studies have shown that the intestinal microbiota and its metabolites, as unique mediators, are involved in the physiological and pathological changes of the body. Therefore, this study explores the relationship between fluid metabolism and diarrhea from the perspective of the intestinal microbiota and its metabolites, aiming to elucidate the biological mechanisms underlying the "promoting urination to regulate bowel movements" therapeutic approach and to clarify the scientific basis for treating diarrhea via the renal-intestinal axis. This research provides new insights for the study of TCM microbiology.

Effect of folpet on hypoglycaemia, intestinal microbiota, and drug resistance genes in mice

BACKGROUND

Folpet is a nonspecific sulfonamide fungicide widely used to protect crops from mildew. However, the in vivo effects of folpet on glucose metabolism homeostasis, gut microbiota, and abundance of drug resistance genes remain unknown. The purpose of this study was to assess the effects of the pesticide, folpet, on glucose metabolism homeostasis, and folpet-induced changes in the intestinal microbiota and resistance genes in mice.

METHODS

Mice were orally administered folpet at 0, 1, 10, and 100 mg/kg body weight/day for 5 weeks. Blood sugar levels in mice were measured after 5 weeks of folpet administration. Metagenomic sequencing and drug resistance gene analyses were performed to explore changes in the abundance of gut microbiota members and drug resistance genes in mice after folpet administration. Correlation analysis was performed using metabolomics to explore the relationship between intestinal microbiota, drug resistance genes, and glucose metabolism.

RESULTS

Mice in the folpet group had significantly lower blood glucose levels than those in the control group. The abundance of Atopobium, Libanicoccus, Collinsella, and Parabacteroides in the intestinal microbiota of folpet-treated mice was significantly higher than that in the control group. However, the abundance of Mailhella, Bilophila, Roseburia, and Bacteroides were reduced in folpet-treated mice. Compared with the control group, the abundance of APH6-Ic and AAC6-Ie-APH2-Ia resistance genes in mice treated with folpet significantly increased. The abundance of tetQ, ermE, and BahA resistance genes was significantly reduced after folpet treatment.

CONCLUSIONS

Folpet is associated with changes in the abundance of gut microbiota in mice and may also affect the abundance of drug-resistance genes and the regulation of blood glucose levels.

A metagenome-wide study of the gut virome in chronic kidney disease

Rationale: Chronic kidney disease (CKD) is a progressively debilitating condition leading to kidney dysfunction and severe complications. While dysbiosis of the gut bacteriome has been linked to CKD, the alteration in the gut viral community and its role in CKD remain poorly understood. Methods: Here, we characterize the gut virome in CKD using metagenome-wide analyses of faecal samples from 425 patients and 290 healthy individuals. Results: CKD is associated with a remarkable shift in the gut viral profile that occurs regardless of host properties, disease stage, and underlying diseases. We identify 4,649 differentially abundant viral operational taxonomic units (vOTUs) and reveal that some CKD-enriched viruses are closely related to gut bacterial taxa such as Bacteroides, [Ruminococcus], Erysipelatoclostridium, and Enterocloster spp. In contrast, CKD-depleted viruses include more crAss-like viruses and often target Faecalibacterium, Ruminococcus, and Prevotella species. Functional annotation of the vOTUs reveals numerous viral functional signatures associated with CKD, notably a marked reduction in nicotinamide adenine dinucleotide (NAD+) synthesis capacity within the CKD-associated virome. Furthermore, most CKD viral signatures are reproducible in the gut viromes of diabetic kidney disease and several other common diseases, highlighting the considerable universality of disease-associated viromes. Conclusions: This research provides comprehensive resources and novel insights into the CKD-associated gut virome, offering valuable guidance for future mechanistic and therapeutic investigations.

The Causal Role of Esophageal Cancer and Gut Microbiota: A Bidirectional Mendelian Randomization Study

AIMS

Gut microbiota are reported to be associated with the incidence and prognosis of Esophageal cancer (EC) but their genetic association is unclear. We carried out a bidirectional MR analysis to assess the causal relationship between EC and gut microbiota from fecal samples.

METHODS

The microbiome genome-wide association studies (GWAS) data of 18,340 individuals provided by MiBioGen consortium and the EC GWAS data (740 esophageal cancers cases and 372 016 controls) provided by UK Biobank were respectively utilized as exposure and/or outcome data. Reliable single nucleotide polymorphisms (SNPs) were obtained after rigorous screening. A bidirectional Mendelian randomization (MR) analysis was conducted using the inverse-variance weighted (IVW) method. The sensitivity analyses including the MR-Egger method, weighted median, weighed mode and leave-one-out method were performed to examine the stability, heterogeneity and pleiotropy of the results.

RESULTS

Forward MR analysis revealed the increase in abundance of the microbial trait by each standard deviation was associated with a higher risk of EC (Coprobacter (OR = 1.001,95%CI = 1.000-1.002, P = .0281, FDR = 0.0424); Ruminococcus1(OR = 1.001,95%CI = 1.000-1.002, P = .0318, FDR = 0.0424); Senegalimassilia (OR = 1.002,95%CI = 1.000-1.003, P = .0062, FDR = 0.0372); Veillonella (OR = 1.001,95%CI = 1.000-1.002, P = .0182, FDR = 0.0372)) or a lower risk of EC (Eubacterium oxidoreducens (OR = 0.999, 95%CI = 0.998-1.000, P = .0379, FDR = 00 433); Lachnospira (OR = 0.998,95%CI = 0.996-1.000, P = .0186, FDR = 0.0372); Romboutsia (OR = 0.999,95%CI = 0.998-1.000, P = .0482, FDR = 0.0482); Turicibacter (OR = 0.999,95%CI = 0.998-1.000, P = .0133, FDR = 0.0372)). Reverse MR analysis showed that genetic liability to EC was also causally linked toincreased susceptibility of changes in the gut microbiome (genera Eggerthella (Beta = 37.63,95%CI = 4.76-70.50, P = .0248, FDR = 0.0331); Coprococcus 2 (Beta = 23.90,95%CI = 1.65-46.15, P = .0353, FDR = 0.0353); Christensenellaceae R.7 (Beta = 22.75,95%CI = 4.22-41.28, P = .0161, FDR = 0.0322); Intestinimonas (Beta = -33.24,95%CI = -54.90-11.58, P = .0026, FDR = 0.0104)).

CONCLUSIONS

Our findings supported a bidirectionally causal relationship between gut microbiota and EC, implying the potential role of gut microbiota in preventing the occurrence and development of EC.

The evolving understanding of systemic mechanisms in organ-specific IgA nephropathy: a focus on gut-kidney crosstalk

The interplay between multiple organs, known as inter-organ crosstalk, represents a complex and essential research domain in understanding the mechanisms and therapies for kidney diseases. The kidneys not only interact pathologically with many other organs but also communicate with other systems through various signaling pathways. It is of paramount importance to comprehend these mechanisms for the development of more efficient therapeutic strategies. Despite extensive research in IgA nephropathy (IgAN), the most common kidney disease, the elaboration mechanism of IgAN remains challenging. Numerous studies suggest that alterations in the intestinal microbiome and its metabolites are pivotal in the progression of IgAN, opening new avenues for understanding its mechanisms. Interestingly, certain presumed probiotics, such as Akkermansia muciniphila, have been implicated in the onset of IgAN, making the exploration of gut microbiota in the context of IgAN pathogenesis even more intriguing. In this review, we summarize the status of gut microbiology studies of IgAN and explore the possible mechanisms and intervention prospects. Future research and treatment directions may increasingly emphasize systemic, multi-organ combined interventions to decelerate the advancement of kidney disease and enhance the overall prognosis of patients.

Metagenomics and metabolomics to investigate the effect of Amygdalus mongolica oil on intestinal microbiota and serum metabolites in rats

BACKGROUND

Renal fibrosis (RF) is an inevitable consequence of multiple manifestations of progressive chronic kidney diseases (CKDs). Mechanism of Amygdalus mongolica (Maxim.) in the treatment of RF needs further investigation.

PURPOSE

The study further investigated the potential mechanism of A. mongolica in the treatment of RF.

METHODS

A rat model of RF was induced by unilateral ureteral obstruction (UUO), followed by treatment with varying dosages of A. mongolica oil for 4 weeks. Body weight was measured weekly. We detected serum levels of interleukin (IL)-6, IL-1β, type Ⅲ procollagen (Col-Ⅲ), type IV collagen (Col-Ⅳ), laminin (LN), hyaluronidase (HA), and tissue levels of albumin (ALB), blood urea nitrogen (BUN), creatinine (Cre), superoxide dismutase (SOD), malondialdehyde (MDA), and hydroxyproline (HYP). Shotgun metagenomics analyzed the composition of the intestinal microbiota. High-performance liquid chromatography coupled with a quadrupole-exactive mass spectrometer (HPLC-Q-Exactive-MS) monitored changes in metabolite levels in serum and gut. Multiple reaction monitoring-mass spectrometry (MRM-MS) determined the levels of amino acids in serum.

RESULTS

A. mongolica oil significantly alleviated indicators related to RF (p < 0.05). A. mongolica oil reduced the ratio of Firmicutes to Bacteroidetes and restored the balance of intestinal microbiota in rats with RF. A. mongolica oil modulated levels of metabolites in gut content and serum. It regulated 11 metabolic pathways including arachidonic acid metabolism. Targeted metabolomics of amino acids showed that 17 amino acids were significantly changed by A. mongolica oil, including L-glycine, L-serine and L-glutamine.

CONCLUSION

A. mongolica oil regulates intestinal microbiota and metabolites, restoring amino acid metabolism to treat RF.

Hyaluronic Acid-Nanocoated Bacteria Generate an Anti-Inflammatory Tissue-Repair Effect in Impaired Gut and Extraintestinal Organs

Diverse extraintestinal diseases are characterized by localized inflammatory responses and tissue damage, accompanied with intestinal inflammation and injury. Here, a dual-functionality and dual-location intervention strategy is reported, which is the use of hyaluronic acid-nanocoated Clostridium butyricum to generate an anti-inflammatory tissue-repair effect in the impaired gut and extraintestinal organs. Nanocoated bacteria attenuate intestinal mucosal inflammation and recover gut barrier integrity by leveraging the immunosuppressive nature of hyaluronic acid and the butyrate-producing ability of Clostridium butyricum. Nanocoated bacteria also alleviate the interstitial inflammation and pathological damage of extraintestinal organs via remodeling microbial metabolites and decreasing microbial translocation. In murine models of acute kidney injury and chronic kidney disease, oral delivery of nanocoated bacteria demonstrates the potency to restore renal function and eliminate renal fibrosis. This work proposes a type of next-generation living therapeutics for treating extraintestinal diseases.

Multi-omics Analysis Reveals Key Gut Microbiota and Metabolites Closely Associated with Huntington's Disease

Dysbiosis of the gut microbiota is closely associated with neurodegenerative diseases, including Huntington's disease (HD). Gut microbiome-derived metabolites are key factors in host-microbiome interactions. This study aimed to investigate the crucial gut microbiome and metabolites in HD and their correlations. Fecal and serum samples from 11 to 26 patients with HD, respectively, and 16 and 23 healthy controls, respectively, were collected. The fecal samples were used for shotgun metagenomics while the serum samples for metabolomics analysis. Integrated analysis of the metagenomics and metabolomics data was also conducted. Firmicutes, Bacteroidota, Proteobacteria, Uroviricota, Actinobacteria, and Verrucomicrobia were the dominant phyla. At the genus level, the presence of Bacteroides, Faecalibacterium, Parabacteroides, Alistipes, Dialister, and Christensenella was higher in HD patients, while the abundance of Lachnospira, Roseburia, Clostridium, Ruminococcus, Blautia, Butyricicoccus, Agathobaculum, Phocaeicola, Coprococcus, and Fusicatenibacter decreased. A total of 244 differential metabolites were identified and found to be enriched in the glycerophospholipid, nucleotide, biotin, galactose, and alpha-linolenic acid metabolic pathways. The AUC value from the integrated analysis (1) was higher than that from the analysis of the gut microbiota (0.8632). No significant differences were found in the ACE, Simpson, Shannon, Sobs, and Chao indexes between HD patients and controls. Our study determined crucial functional gut microbiota and potential biomarkers associated with HD pathogenesis, providing new insights into the role of the gut microbiota-brain axis in HD occurrence and development.

The Role of Indoxyl Sulfate in Exacerbating Colorectal Cancer During Chronic Kidney Disease Progression: Insights into the Akt/β-Catenin/c-Myc and AhR/c-Myc Pathways in HCT-116 Colorectal Cancer Cells

Epidemiological studies suggest an increased risk of colorectal cancer (CRC) aggravation in patients with chronic kidney disease (CKD). Our previous study demonstrated that indoxyl sulfate, a uremic toxin whose concentration increases with CKD progression, exacerbates CRC through activation of the AhR and Akt pathways. Consequently, indoxyl sulfate has been proposed to be a significant link between CKD progression and CRC aggravation. The present study aimed to investigate the roles of c-Myc and β-Catenin, which are hypothesized to be downstream factors of indoxyl sulfate-induced AhR and Akt activation, in CRC cell proliferation and EGF sensitivity in HCT-116 CRC cells. Indoxyl sulfate significantly induced CRC cell proliferation at concentrations exceeding 62.5 µM, a process suppressed by the c-Myc inhibitor 10058-F4. Indoxyl sulfate activated the Akt/β-Catenin/c-Myc pathway as evidenced by the Akt inhibitor MK2206, which decreased both β-Catenin and c-Myc protein levels, and the β-Catenin inhibitor XAV-939, which reduced c-Myc protein levels. The AhR antagonist CH223191 also inhibited c-Myc upregulation, indicating involvement of the AhR/c-Myc pathway. MK2206 partially attenuated the indoxyl sulfate-induced AhR transcriptional activity, suggesting that Akt activation influences the AhR/c-Myc pathway. MK2206, CH223191, and 10058-F4 suppressed the increase in EGFR protein levels induced by indoxyl sulfate, indicating that the Akt/β-Catenin/c-Myc and AhR/c-Myc pathways enhance the sensitivity of HCT-116 CRC cells to EGF. These findings indicate that the elevation of indoxyl sulfate levels in the blood, due to CKD progression, could worsen CRC by promoting the proliferation of CRC cells and enhancing EGF signaling. Therefore, indoxyl sulfate could potentially serve as a therapeutic target for CRC aggravation in patients with CKD.

Alcohol-induced gut microbial reorganization and associated overproduction of phenylacetylglutamine promotes cardiovascular disease

The mechanism(s) underlying gut microbial metabolite (GMM) contribution towards alcohol-mediated cardiovascular disease (CVD) is unknown. Herein we observe elevation in circulating phenylacetylglutamine (PAGln), a known CVD-associated GMM, in individuals living with alcohol use disorder. In a male murine binge-on-chronic alcohol model, we confirm gut microbial reorganization, elevation in PAGln levels, and the presence of cardiovascular pathophysiology. Fecal microbiota transplantation from pair-/alcohol-fed mice into naïve male mice demonstrates the transmissibility of PAGln production and the CVD phenotype. Independent of alcohol exposure, pharmacological-mediated increases in PAGln elicits direct cardiac and vascular dysfunction. PAGln induced hypercontractility and altered calcium cycling in isolated cardiomyocytes providing evidence of improper relaxation which corresponds to elevated filling pressures observed in vivo. Furthermore, PAGln directly induces vascular endothelial cell activation through induction of oxidative stress leading to endothelial cell dysfunction. We thus reveal that the alcohol-induced microbial reorganization and resultant GMM elevation, specifically PAGln, directly contributes to CVD.

The Gut-Kidney Axis in Chronic Kidney Diseases

The gut-kidney axis represents the complex interactions between the gut microbiota and kidney, which significantly impact the progression of chronic kidney disease (CKD) and overall patient health. In CKD patients, imbalances in the gut microbiota promote the production of uremic toxins, such as indoxyl sulfate and p-cresyl sulfate, which impair renal function and contribute to systemic inflammation. Mechanisms like endotoxemia, immune activation and oxidative stress worsen renal damage by activating pro-inflammatory and oxidative pathways. Insights into these mechanisms highlight the impact of gut-derived metabolites, bacterial translocation, and immune response changes on kidney health, suggesting new potential approaches for CKD treatment. Clinical applications, such as dietary interventions, prebiotics, probiotics and fecal microbiota transplantation, are promising in adjusting the gut microbiota to alleviate CKD symptoms and slow disease progression. Current research highlights the clinical relevance of the gut-kidney axis, but further study is essential to clarify these mechanisms' diagnostic biomarkers and optimize therapeutic interventions. This review emphasizes the importance of an integrated approach to CKD management, focusing on the gut microbiota as a therapeutic target to limit kidney injury.

Impaired renal transporter gene expression and uremic toxin excretion as aging hallmarks in cats with naturally occurring chronic kidney disease

Aging leads to nephron senescence and chronic kidney disease (CKD). In cats, indoxyl sulfate (IxS) has been previously quantified and associated with CKD, and little is known about tubular transporters. Two cohorts of cats aged 6 to 21 years were enrolled. Cohort 1 included 41 colony cats with 28 control and 13 CKD cats. Cohort 2 had 30 privately-owned cats with 10 control and 20 CKD cats. In cohort 1, serum concentrations of IxS, trimethylamine N-oxide (TMAO), p-cresol sulfate (PCS), and phenyl sulfate were higher in CKD vs. control cats (all P<0.05). This observation was independently validated in cohort 2. Renal cortical and medullar tissues were collected from a third cohort of cats euthanized for humane reasons unrelated to the study. We provided the evidence that renal tubular transporter genes, OAT1, OAT4, OATP4C1, and ABCC2, but not OAT3, were expressed in the kidneys of cats, and their expressions were downregulated in CKD (all FDR<0.1). Cats and humans share 90.9%, 77.8%, and 82.5% identities in OAT1, OATP4C1, and ABCC2 proteins, respectively. In healthy cats, circulating TMAO and IxS are significantly correlated with age. Our study reveals impaired uremic toxin secretion and tubular transporter expression in cats with CKD.

MMETHANE: interpretable AI for predicting host status from microbial composition and metabolomics data

Metabolite production, consumption, and exchange are intimately involved with host health and disease, as well as being key drivers of host-microbiome interactions. Despite the increasing prevalence of datasets that jointly measure microbiome composition and metabolites, computational tools for linking these data to the status of the host remain limited. To address these limitations, we developed MMETHANE, an open-source software package that implements a purpose-built deep learning model for predicting host status from paired microbial sequencing and metabolomic data. MMETHANE incorporates prior biological knowledge, including phylogenetic and chemical relationships, and is intrinsically interpretable, outputting an English-language set of rules that explains its decisions. Using a compendium of six datasets with paired microbial composition and metabolomics measurements, we showed that MMETHANE always performed at least on par with existing methods, including blackbox machine learning techniques, and outperformed other methods on >80% of the datasets evaluated. We additionally demonstrated through two cases studies analyzing inflammatory bowel disease gut microbiome datasets that MMETHANE uncovers biologically meaningful links between microbes, metabolites, and disease status.

Gut Dysbiosis and Probiotic Therapy in Chronic Kidney Disease: A Comprehensive Review

Chronic kidney disease (CKD) is a multifactorial disease affecting more than 13.4% of the world's population and is a growing public health problem. It is silent in its early stages and leads to irreversible kidney damage as the disease progresses. A key factor in this progression is the bidirectional relationship between CKD and gut dysbiosis, which creates an imbalance that promotes the accumulation of uremic toxins (UTs), contributing to renal fibrosis, endothelial dysfunction, and decreased glomerular filtration rate. In addition, CKD itself exacerbates gut dysbiosis by altering the composition of the gut microbiota (GM) and promoting the growth of pathogenic microorganisms. Therefore, it is crucial to explore new therapeutic strategies, and the use of probiotics and synbiotics has shown promise in modulating the GM. Numerous preclinical studies have shown that the use of probiotics in CKD has a beneficial effect on the kidney by reducing UTs, apoptosis, inflammation, and oxidative stress. Probiotic treatment has also been associated with restoration of intestinal integrity, modulation of microbial composition and diversity, and increased production of short-chain fatty acids (SCFAs). These positive results have also been observed in patients at different stages of CKD, where the use of probiotics and/or synbiotics was able to improve creatinine levels and uremic parameters and alleviate abdominal discomfort, in addition to modulating GM and reducing serum endotoxin levels. Although recent studies have explored the benefits of probiotics in the treatment of CKD, further research is needed to determine their long-term efficacy and clinical relevance. This review focuses on the factors driving gut dysbiosis in CKD, its role in disease progression, and the potential of probiotics as a therapeutic strategy.

Gut Microbial Dysbiosis and Implications in Solid Organ Transplantation

The gut microbiome has been shown to play a significant role in solid organ transplantation, potentially influencing graft function and patient outcomes. Dysbiosis, characterized by reduced microbial diversity and an increase in pathogenic taxa, has been linked to higher incidences of allograft rejection, graft dysfunction, and post-transplant mortality. Several studies suggest that the gut microbiome might be able to serve as both a biomarker and a therapeutic target, potentially guiding personalized immunosuppressive therapies and other interventions to improve outcomes after solid organ transplantation. As summarized in this review, clinical studies have shown that specific microbial shifts correlate with adverse outcomes, including acute rejection and chronic allograft dysfunction. As research surrounding the relationship between the gut microbiome and solid organ transplant progresses, the integration of microbial analysis into clinical practice has the potential to revolutionize post-transplant care, offering new avenues to improve graft survival and patient quality of life. This review aims to provide a comprehensive overview of the relationship between gut microbial dysbiosis and transplantation outcomes, emphasizing the impact on kidney, liver, lung, and heart transplant recipients.

Salt-Responsive Gut Microbiota Induces Sex-Specific Blood Pressure Changes

BACKGROUND

Tryptophan metabolism is important in blood pressure regulation. The tryptophan-indole pathway is exclusively mediated by the gut microbiota. ACE2 (angiotensin-converting enzyme 2) participates in tryptophan absorption, and a lack of ACE2 leads to changes in the gut microbiota. The gut microbiota has been recognized as a regulator of blood pressure. Furthermore, there is ample evidence for sex differences in the gut microbiota. However, it is unclear whether such sex differences impact blood pressure differentially through the tryptophan-indole pathway.

METHODS

To study the sex-specific mechanisms of gut microbiota-mediated tryptophan-indole pathway in hypertension, we generated a novel rat model with Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats-associated protein 9)-targeted deletion of Ace2 in the Dahl salt-sensitive rat. Cecal microbiota transfers from donors of both sexes to female S recipients were performed. Also, Dahl salt-sensitive rats of both sexes were orally gavaged with indole to investigate blood pressure response.

RESULTS

The female gut microbiota and its tryptophan-indole pathway exhibited greater buffering capacity when exposed to tryptophan, due to Ace2 deficiency, and salt. In contrast, the male gut microbiota and its tryptophan-indole pathway were more vulnerable. Female rats with male cecal microbiota responded to salt with a higher blood pressure increase compared with those with female cecal microbiota. Indole, a tryptophan-derived metabolite produced by gut bacteria, increased blood pressure in male but not in female rats. Moreover, salt altered host-mediated tryptophan metabolism, characterized by reduced serum serotonin of both sexes and higher levels of kynurenine derivatives in the females.

CONCLUSIONS

We uncovered a novel sex-specific mechanism in the gut microbiota-mediated tryptophan-indole pathway in blood pressure regulation. Salt tipped the tryptophan metabolism between the host and gut microbiota in a sex-dependent manner. Our study provides evidence for a novel concept that gut microbiota and its metabolism play sex-specific roles in the development of salt-sensitive hypertension.

Protective effect and mechanism of Xiaoyu Xiezhuo decoction on ischemia-reperfusion induced acute kidney injury based on gut-kidney crosstalk

This study aimed to explore the mechanism of Xiaoyu Xiezhuo decoction (XXD) on ischemia-reperfusion-induced acute kidney injury (IRI-AKI) using network pharmacology methods and gut microbiota analysis. A total of 1778 AKI-related targets were obtained, including 140 targets possibly regulated by AKI in XXD, indicating that the core targets were mainly enriched in inflammatory-related pathways, such as the IL-17 signaling pathway and TNF signaling pathway. The unilateral IRI-AKI animal model was established and randomly divided into four groups: the sham group, the AKI group, the sham + XXD group, and the AKI + XXD group. Compared with the rats in the AKI group, XXD improved not only renal function, urinary enzymes, and biomarkers of renal damage such as Kim-1, cystatin C, and serum inflammatory factors such as IL-17, TNF-α, IL-6, and IL 1-β, but also intestinal metabolites including lipopolysaccharides, d-lactic acid, indoxyl sulfate, p-cresyl sulfate, and short-chain fatty acids. XXD ameliorated renal and colonic pathological injury as well as inflammation and chemokine gene abundance, such as IL-17, TNF-α, IL-6, IL-1β, ICAM-1, and MCP-1, in AKI rats via the TLR4/NF-κB/NLRP3 pathway, reducing the AKI score, renal pathological damage, and improving the intestinal mucosa's inflammatory infiltration. It also repaired markers of the mucosal barrier, including claudin-1, occludin, and ZO-1. Compared with the rats in the AKI group, the α diversity was significantly increased, and the Chao1 index was significantly enhanced after XXD treatment in both the sham group and the AKI group. The treatment group significantly reversed this change in microbiota.

Acute kidney disease in mice is associated with early cardiovascular dysfunction

Acute kidney injury (AKI) and chronic kidney disease (CKD) are major health concerns due to their increasing incidence and high mortality. They are interconnected syndromes; AKI without recovery evolves into acute kidney disease (AKD), which can indicate an AKI-to-CKD transition. Both AKI and CKD are associated with a risk of long-term cardiovascular complications, but whether vascular and cardiac dysfunctions can occur as early as the AKD period has not been studied extensively. In a mouse model of kidney injury (KI) with non-recovery, we performed vasoreactivity and echocardiography analyses on days 15 (D15) and 45 (D45) after KI. We determined the concentrations of two major gut-derived protein-bound uremic toxins known to induce cardiovascular toxicity-indoxyl sulfate (IS) and para-cresyl sulfate (PCS)-and the levels of inflammation and contraction markers on D7, D15, and D45. Mice with KI showed acute tubular and interstitial kidney lesions on D7 and D15 and chronic glomerulosclerosis on D45. They showed significant impairment of aorta relaxation and systolic-diastolic heart function, both on D15 and D45. Such dysfunction was associated with downregulation of the expression of two contractile proteins, αSMA and SERCA2a, with a more pronounced effect on D15 than on D45. KI was also followed by a rapid increase in IS and PCS serum concentrations and the expression induction of pro-inflammatory cytokines and endothelial adhesion molecules in serum and cardiovascular tissues. Therefore, these results highlight that AKD leads to early cardiac and vascular dysfunctions. How these dysfunctions could be managed to prevent cardiovascular events deserves further study.

Effects of live and pasteurized forms of Lactobacillus casei Zhang on acute kidney injury and chronic renal fibrosis

Lactobacillus casei Zhang (Lac.z), isolated from traditional sour horse milk in Inner Mongolia, can alleviate various diseases and promote health. Our previous studies found that pretreatment with live Lac.z (L-Lac.z) could significantly attenuate acute kidney injury and delay the progression of chronic renal fibrosis. However, it is unknown whether these effects could be maintained by pasteurized Lac.z (P-Lac.z). Mouse models of acute kidney injury and chronic renal fibrosis induced by renal bilateral ischemia-reperfusion (BIR) surgery were treated with L-Lac.z or P-Lac.z by gavage. Serum and kidney samples were collected to analyze the extent of renal injury and fibrosis, and proteomics was used to explore the potential mechanisms underlying the differences in the effects of the two forms of Lac.z. The results revealed that treatment with L-Lac.z led to a reduction in serum urea nitrogen levels and in less renal tubular injury and subsequent renal fibrosis after BIR-induced renal injury, whereas these effects were not observed in the P-Lac.z group. Proteomic analysis revealed 19 up-regulated proteins and 39 down-regulated proteins in the P-Lac.z group, and these gene products were associated with growth and stress resistance. The specific nephroprotective effects of L-Lac.z may be independent of the interaction of live probiotics with the host.

NMFGOT: a multi-view learning framework for the microbiome and metabolome integrative analysis with optimal transport plan

The rapid development of high-throughput sequencing techniques provides an unprecedented opportunity to generate biological insights into microbiome-related diseases. However, the relationships among microbes, metabolites and human microenvironment are extremely complex, making data analysis challenging. Here, we present NMFGOT, which is a versatile toolkit for the integrative analysis of microbiome and metabolome data from the same samples. NMFGOT is an unsupervised learning framework based on nonnegative matrix factorization with graph regularized optimal transport, where it utilizes the optimal transport plan to measure the probability distance between microbiome samples, which better dealt with the nonlinear high-order interactions among microbial taxa and metabolites. Moreover, it also includes a spatial regularization term to preserve the spatial consistency of samples in the embedding space across different data modalities. We implemented NMFGOT in several multi-omics microbiome datasets from multiple cohorts. The experimental results showed that NMFGOT consistently performed well compared with several recently published multi-omics integrating methods. Moreover, NMFGOT also facilitates downstream biological analysis, including pathway enrichment analysis and disease-specific metabolite-microbe association analysis. Using NMFGOT, we identified the significantly and stable metabolite-microbe associations in GC and ESRD diseases, which improves our understanding for the mechanisms of human complex diseases.

The gut microbiome, chronic kidney disease, and sarcopenia

Sarcopenia is a prevalent condition in patients with chronic kidney disease (CKD), intricately linked to adverse prognoses, heightened cardiovascular risks, and increased mortality rates. Extensive studies have found a close and complex association between gut microbiota, kidney and muscle. On one front, patients with CKD manifest disturbances in gut microbiota and alterations in serum metabolites. These abnormal microbiota composition and metabolites in turn participate in the development of CKD. On another front, altered gut microbiota and its metabolites may lead to significant changes in metabolic homeostasis and inflammation, ultimately contributing to the onset of sarcopenia. The disturbance of gut microbial homeostasis, coupled with the accumulation of toxic metabolites, exerts deleterious effects on skeletal muscles in CKD patients with sarcopenia. This review meticulously describes the alterations observed in gut microbiota and its serum metabolites in CKD and sarcopenia patients, providing a comprehensive overview of pertinent studies. By delving into the intricate interplay of gut microbiota and serum metabolites in CKD-associated sarcopenia, we aim to unveil novel treatment strategies for ameliorating their symptoms and prognosis.

Fusobacterium nucleatum-infected periodontitis promotes renal interstitial fibrosis in rats through the TGF-β/SMAD2/3 and β-catenin signaling pathways

OBJECTIVES

Periodontitis is associated with Fusobacterium nucleatum (F.n) infection. Although the colonization of renal tissue by F.n is well documented, its specific role in kidney disease has yet to be determined. This study aimed to investigate the potential association between F.n-induced periodontitis and renal interstitial fibrosis.

METHODS

The rat gingival sulcus was injected with F.n suspension, while the control group (NC) was injected with PBS. The levels of total protein (TP), albumin (ALB), creatinine, and urea nitrogen (BUN) in rat serum and/or urine were quantified using the appropriate kits. Renal interstitial fibrosis and epithelial-mesenchymal transition (EMT) were evaluated in rats using Masson staining, Periodic Schiff-Methenamine (PASM) staining, and immunohistochemical staining. The levels of fibrosis- and EMT-related proteins and the TGF-β/SMAD2/3 and β-catenin signaling pathways were determined using Western blot analysis. F.n in the kidney tissues was quantitatively determined using bacterial 16S rRNA technology.

RESULTS

Serum levels of TP, ALB, creatinine, and BUN were not significantly decreased in F.n-infected rats with periodontitis. The levels of creatinine and ALB in the urine were not statistically different between two groups. Masson and PASM staining showed that F.n-induced periodontitis could promote renal interstitial fibrosis in rats. The levels of collagen I, fibronectin (FN), vimentin, and α-SMA were upregulated in the kidney tissues of rats with F.n-induced periodontitis and in F.n-treated HK-2 cells. However, E-cadherin levels were reduced. F.n promoted renal interstitial and HK-2 cell fibrosis in rats by modulating the TGF-β/SMAD2/3 and β-catenin signaling pathways. F.n colonization increased renal interstitial fibrosis in rats.

CONCLUSION

F.n-induced periodontitis promoted EMT by activating the TGF-β/SMAD2/3 and β-catenin signaling pathways, thus promoting renal interstitial fibrosis in rats.

Language model-guided anticipation and discovery of unknown metabolites

Despite decades of study, large parts of the mammalian metabolome remain unexplored. Mass spectrometry-based metabolomics routinely detects thousands of small molecule-associated peaks within human tissues and biofluids, but typically only a small fraction of these can be identified, and structure elucidation of novel metabolites remains a low-throughput endeavor. Biochemical large language models have transformed the interpretation of DNA, RNA, and protein sequences, but have not yet had a comparable impact on understanding small molecule metabolism. Here, we present an approach that leverages chemical language models to discover previously uncharacterized metabolites. We introduce DeepMet, a chemical language model that learns the latent biosynthetic logic embedded within the structures of known metabolites and exploits this understanding to anticipate the existence of as-of-yet undiscovered metabolites. Prospective chemical synthesis of metabolites predicted to exist by DeepMet directs their targeted discovery. Integrating DeepMet with tandem mass spectrometry (MS/MS) data enables automated metabolite discovery within complex tissues. We harness DeepMet to discover several dozen structurally diverse mammalian metabolites. Our work demonstrates the potential for language models to accelerate the mapping of the metabolome.

Gut microbiota and renal fibrosis

Renal fibrosis represents a critical pathological condition in the progression of renal dysfunction, characterized by aberrant accumulation of extracellular matrix (ECM) and structural alterations in renal tissue. Recent research has highlighted the potential significance of gut microbiota and demonstrated their influence on host health and disease mechanisms through the production of bioactive metabolites. This review examines the role of alterations in gut microbial composition and their metabolites in the pathophysiological processes underlying renal fibrosis. It delineates current therapeutic interventions aimed at modulating gut microbiota composition, encompassing dietary modifications, pharmacological approaches, and probiotic supplementation, while evaluating their efficacy in mitigating renal fibrosis. Through a comprehensive analysis of current research findings, this review enhances our understanding of the bidirectional interaction between gut microbiota and renal fibrosis, establishing a theoretical foundation for future research directions and potential clinical applications in this domain.

Multi-omics insights implicate the remodeling of the intestinal structure and microbiome in aging

Background

Aging can impair the ability of elderly individuals to fight infections and trigger persistent systemic inflammation, a condition known as inflammaging. However, the mechanisms underlying the development of inflammaging remain unknown.

Methods

We conducted 16S rRNA sequencing of intestinal contents from young and old C57BL/6J mice to elucidate changes in gut microbiota diversity and microbial community composition after aging. Aging-related differential bacterial taxa were then identified, and their abundance trends were validated in human samples. The variances in intestinal barrier function and circulating endotoxin between groups were also assessed. Furthermore, widely targeted metabolomics was conducted to characterize metabolic profiles after aging and to investigate the key metabolic pathways enriched by the differential metabolites.

Results

Our findings demonstrated an increase in relative proportion of pathogenic bacteria with age, a trend also revealed in healthy populations of different age groups. Additionally, aging individuals exhibited reduced intestinal barrier function and increased circulating endotoxin levels. Widely targeted metabolomics revealed a significant increase in various secondary bile acid metabolites after aging, positively correlated with the relative abundance of several aging-related bacterial taxa. Furthermore, old group had lower levels of various anti-inflammatory or beneficial metabolites. Enrichment analysis identified the starch and sucrose metabolism pathway as potentially the most significantly impacted signaling pathway during aging.

Conclusion

This study aimed to provide insights into the complex interactions involved in organismal inflammaging through microbial multi-omics. These findings lay a solid foundation for future research aimed at identifying novel biomarkers for the clinical diagnosis of aging-related diseases or potential therapeutic targets.

Intestinal microbiome changes and mechanisms of maintenance hemodialysis patients with constipation

Background

Constipation is a common symptom in maintenance hemodialysis patients and greatly affects the quality of survival of hemodialysis patients. Fecal microbiota transplantation and probiotics are feasible treatments for functional constipation, but there is still a gap in the research on the characteristics of gut flora in patients with maintenance hemodialysis combined with constipation. The aim of this study is to clarify the characteristics of the intestinal flora and its changes in maintenance hemodialysis patients with constipation.

Methods

Fecal samples were collected from 45 participants, containing 15 in the maintenance hemodialysis constipation group,15 in the maintenance hemodialysis non-constipation group and 15 in the healthy control group. These samples were analyzed using 16S rRNA gene sequencing. The feature of the intestinal microbiome of maintenance hemodialysis constipation group and the microbiome differences among the three groups were elucidated by species annotation analysis, α-diversity analysis, β-diversity analysis, species difference analysis, and predictive functional analysis.

Results

The alpha diversity analysis indicated that maintenance hemodialysis constipation group was less diverse and homogeneous than maintenance hemodialysis non-constipation group and healthy control group. At the genus level, the top ten dominant genera in maintenance hemodialysis constipation group patients were Enterococcus, Escherichia-Shigella, Bacteroides, Streptococcus, Bifidobacterium, Ruminococcus_gnavus_group, Lachnospiraceae_unclassified, Faecalibacterium, Akkermansia and UCG-002. Compared with non-constipation group, the Enterococcus, Rhizobiales_unclassified, Filomicrobium, Eggerthella, Allobaculum, Prevotella_7, Gordonibacter, Mitochondria_unclassified, Lachnoanaerobaculum were significantly higher in constipation group (p<0.05). Compared with non-constipation group, the Kineothrix, Rhodopirellula, Weissella were significantly lower in constipation group (p<0.05). The predictive functional analysis revealed that compared with non-constipation group, constipation group was significantly enriched in pathways associated with pyruate metabolism, flavonoid biosynthesis.

Conclusions

This study describes for the first time the intestinal microbiome characteristics of maintenance hemodialysis patients with constipation. The results of this study suggest that there is a difference in the intestinal flora between maintenance hemodialysis patients with constipation and maintenance hemodialysis patients without constipation.

Mizhuo Guanchangye enema delays the decline of renal function in rats with chronic kidney disease by intervening in the TLR4/MyD88/NF-κB pathway

Background

Chronic kidney disease (CKD) is a prevalent chronic condition that poses a significant threat to human health. There is a close connection between the gut and kidneys, jointly influencing the onset and progression of CKD through the "gut-kidney axis." Traditional Chinese medicine has shown potential in CKD treatment, but the specific mechanisms require further investigation.

Objectives

This study aims to explore the protective effects of Mizhuo Enema (MZGCY) on kidney function in CKD rats by regulating the TLR4/MyD88/NF-κB signaling pathway.

Methods

The researcher employed a CKD rat model, which was divided into four groups: Control, Model, half-dose Mizhuo Guanchangye (1/2 MZGCY), and full-dose Mizhuo Guanchangye (MZGCY). Post enema administration, assessments were conducted on kidney function indicators, which included blood urea nitrogen (BUN), serum creatinine (SCR), and 24-h urinary protein. Additionally, measurements were taken for intestinal toxic substances such as indoxyl sulfate (IS) and lipopolysaccharide (LPS), as well as inflammatory factors interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). Examinations of pathological changes in both the intestines and kidneys were also performed. During this process, immunofluorescence was utilized to detect the expression levels of proteins toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), and nuclear factor kappa B (NF-κB) in the intestinal tissues.

Results

It was found that after enema treatment, the BUN, SCR, and 24-h urinary protein levels in the MZGCY and 1/2 MZGCY groups significantly decreased, indicating notable improvement in kidney function. Compared to the model group, the IS, LPS, IL-6, and TNF-α levels in the MZGCY and 1/2 MZGCY groups were significantly reduced. Immunofluorescence showed a marked decrease in the expression of TLR4, MyD88, and NF-κB proteins in the intestines of the MZGCY group.

Conclusion

MZGCY significantly reduces the levels of intestinal toxins and inflammatory factors in the serum of CKD rats by interfering with the TLR4/MyD88/NF-κB signaling pathway, thereby improving intestinal and renal pathological changes and delaying CKD progression. This study demonstrates that MZGCY has significant renal protective effects, providing a new potential approach for CKD treatment.