Vascular Calcification and the Gut and Blood Microbiome in Chronic Kidney Disease Patients on Peritoneal Dialysis: A Pilot Study

Involvement of intestinal mucosal microbiota in adenine-induced liver function injury

Adenine is frequently utilized as a model medication for chronic renal disease. Adenine can affect organs other than the kidneys, including the heart and the intestine. The liver is a vital organ involved in the in vivo metabolism of adenine. Adenine may negatively impact liver function. Research indicated that adenine caused dysbiosis of the gut microbiota in mice. Investigations into the gut-liver axis have demonstrated a substantial association between drug-induced hepatic dysfunction and gut microbiota. Consequently, we delivered distinct dosages of adenine via gavage to mice to examine the correlation between adenine-induced liver impairment and gut microbiota dysbiosis. Mice were treated with low-dose adenine suspension (NLA), medium-dose adenine suspension (NMA), high-dose adenine suspension (NHA), and sterile water (NC) as a control. The results indicated that mice in the NLA, NMA, and NHA groups had decreased body weight and a reduction in liver index. Subsequent to adenine administration, the concentrations of AST, ALT, and LDH increased, whereas SDH levels decreased. As doses increased, liver function impairment and hepatic energy metabolism abnormalities aggravated. Adenine also damaged the colonic architecture in mice. Moreover, adenine modified the makeup and structure of the gut mucosal microbiota, enhancing specific bacterial genera and influencing the microbiota's energy metabolism-related functions. The results of our research established a correlation among certain bacteria, liver function injury, and hepatic energy metabolism. The gut mucosal microbiota was involved in adenine-induced liver injury and hepatic energy metabolism. These results can offer novel insights into the role of gut microbiota in drug-induced liver injury and provide specific guidelines for the modeling and therapeutic application of adenine.

Association between cumulative intake of sugar-sweetened and artificially sweetened beverages and progression of coronary calcification: Insights from the CARDIA study

BACKGROUND AND AIMS

This study investigates the relationship between the cumulative intake of artificially sweetened beverages (ASBs) and sugar-sweetened beverages (SSBs) during young adulthood and the progression of coronary artery calcium (CAC) by midlife, using data from the Coronary Artery Risk Development in Young Adults study.

METHODS AND RESULTS

We included 2,466 participants with CAC measurement via computed tomography at the 15th, 20th, and 25th year follow-ups. Dietary intake was assessed using the CARDIA Diet History at baseline and years 7. Cumulative average beverage intake was calculated and categorized. Multivariable Cox regression models adjusted for demographic, lifestyle, and cardiovascular risk factors assessed associations between beverages consumption and CAC progression. Among the included participants, 1107 (44.9 %) were male, 1439 (58.4 %) were white, and the average age was 40.4 years with a standard deviation of 3.5 years. Over a 9.2±1.8-year follow-up, CAC progression was recorded in 715 participants. Higher cumulative ASBs intake was associated with increased CAC progression risk, with hazard ratios (95%CI, P-value) for low and high ASBs consumption being 1.35 (1.14, 1.60; P < 0.001) and 1.54 (1.15, 2.07; P < 0.001) compared to non-consumers. Participants consuming >2 servings/day of SSBs had a 37 % higher CAC progression risk (HR 1.37, 95 % CI 1.14-1.64, P < 0.001). However, no significant association was found between SSB consumption and CAC progression after adjusting for confounders.

CONCLUSIONS

Prolonged consumption of beverages, especially ASBs, in young adults is linked to an increased risk of CAC progression.

Etiological stratification and prognostic assessment of haemophagocytic lymphohistiocytosis by machine learning on onco-mNGS data and clinical data

Introduction

Hemophagocytic lymphohistiocytosis (HLH) is a rare, complicated and life threatening hyperinflammatory syndrome that maybe triggered by various infectious agents, malignancies and rheumatologic disorders. Early diagnosis and identification of the cause is essential to initiate appropriate treatment and improve the quality of life and survival of patients. The recently developed Onco-mNGS technology can be successfully used for simultaneous detection of infections and tumors.

Methods

In the present study, 92 patients with clinically confirmed HLH were etiologically subtyped for infection, tumor and autoimmunity based on CNV and microbial data generated by Onco-mNGS technology, and a predictive model was developed and validated for the differential diagnosis of the underlying disease leading to secondary HLH. Furthermore, the treatment outcomes of patients with HLH triggered by EBV infection and non-EBV infection were evaluated, respectively.

Results

The current study demonstrated that the novel Onco-mNGS can identify the infection and malignancy- related triggers among patients with secondary HLH. A random forest classification model based on CNV profile, infectious pathogen spectrum and blood microbial community was developed to better identify the different HLH subtypes and determine the underlying triggers. The prognosis for treatment of HLH patients is not only associated with CNV, but also with the presence of pathogens and non- pathogens in peripheral blood. Higher CNV burden along with frequent deletions on chromosome 19, higher pathogen burden and lower non-pathogenic microbes were prognosis factors that significantly related with unfavorable treatment outcomes.

Discussion

Our study provided comprehensive knowledge in the triggers and prognostic predictors of patients with secondary HLH, which may help early diagnosis and appropriate targeted therapy, thus improving the survival and prognosis of the patients.

Colorectal cancer-specific microbiome in peripheral circulation and cancer tissues

Introduction

Accumulating evidence has supported that gut microbiota and metabolite profiles play indispensable roles in the pathogenesis of colorectal cancer (CRC), which ranks as the third most common cancer and the second leading cause of cancer-related deaths worldwide. However, alterations in tumoral or circulating microbiomes in CRC remain incompletely understood. It has been well-documented that tissue or serum microbiomes with low microbial biomass could be screened by use of 2bRAD sequencing for microbiome (2bRAD-M) at the species resolution.

Methods

In order to validate the microbial biomarkers distinguishing CRC and the variations in microorganisms present in serum and tumors, we performed 2bRAD-M to characterize the microbiomes in serum and cancer tissues of CRC patients with and without lymph node or liver metastasis.

Results

The composition of dominated microbiota in serum was different from that of tissue samples, while the microbial community composition of tumors was similar to that of the tumor-adjacent tissues. The analysis of α-diversity and β-diversity has revealed notable variations in serum microbiota diversities in CRC patients, particularly those with liver metastasis. Multiple CRC-specific microbial species, such as Moraxella A cinereus, Flavobacterium sp001800905, and Acinetobacter albensis, were identified in serum. Complicated functions and KEGG pathways were also confirmed in CRC according to the metastasis status.

Discussion

This study has found significant alterations in the microbial compositions and diversities in CRC and CRC-specific microbial species in both circulation and cancer tissues, which may serve as promising biomarkers for the screening, diagnosis and prognosis prediction of CRC. In particular, CRC-specific bacterial taxa are promising markers, holding transformative potentials in establishing personalized screening and risk stratification, refining much earlier non-invasive diagnostic approaches, and enhancing diagnostic sensitivity.

Gut Microbiome Is Related to Cognitive Impairment in Peritoneal Dialysis Patients

Gut microbiota disturbances may influence cognitive function, increasing uremic toxins and inflammation in dialysis patients; therefore, we aimed to evaluate the association of the gut microbiota profile with cognitive impairment (CI) in patients on automated peritoneal dialysis (APD). In a cross-sectional study, cognitive function was evaluated using the Montreal Cognitive Assessment in 39 APD patients and classified as normal cognitive function and CI. The gut microbiota was analyzed using the 16S rRNA gene sequencing approach. All patients had clinical, biochemical and urea clearance evaluations. Eighty-two percent of patients were men, with a mean age of 47 ± 24 years and 11 (7-48) months on PD therapy; 64% had mild CI. Patients with CI were older (53 ± 16 vs. 38 ± 14, p = 0.006) and had a higher frequency of diabetes mellitus (56% vs. 21%, p = 0.04) and constipation (7% vs. 48%, p = 0.04) and lower creatinine concentrations (11.3 ± 3.7 vs. 14.9 ± 5.4, p = 0.02) compared to normal cognitive function patients. Patients with CI showed a preponderance of S24_7, Rikenellaceae, Odoribacteraceae, Odoribacter and Anaerotruncus, while patients without CI had a greater abundance of Dorea, Ruminococcus, Sutterella and Fusobacteria (LDA score (Log10) > 2.5; p < 0.05). After glucose and age adjustment, Odoribacter was still associated with CI. In conclusion, patients with CI had a different gut microbiota characterized by the higher abundance of indole-producing and mucin-fermenting bacteria compared to normal cognitive function patients.

Blood Microbiota and Its Products: Mechanisms of Interference with Host Cells and Clinical Outcomes

In healthy conditions, blood was considered a sterile environment until the development of new analytical approaches that allowed for the detection of circulating bacterial ribosomal DNA. Currently, debate exists on the origin of the blood microbiota. According to advanced research using dark field microscopy, fluorescent in situ hybridization, flow cytometry, and electron microscopy, so-called microbiota have been detected in the blood. Conversely, others have reported no evidence of a common blood microbiota. Then, it was hypothesized that blood microbiota may derive from distant sites, e.g., the gut or external contamination of blood samples. Alteration of the blood microbiota's equilibrium may lead to dysbiosis and, in certain cases, disease. Cardiovascular, respiratory, hepatic, kidney, neoplastic, and immune diseases have been associated with the presence of Gram-positive and Gram-negative bacteria and/or their products in the blood. For instance, lipopolysaccharides (LPSs) and endotoxins may contribute to tissue damage, fueling chronic inflammation. Blood bacteria can interact with immune cells, especially with monocytes that engulf microorganisms and T lymphocytes via spontaneous binding to their membranes. Moreover, LPSs, extracellular vesicles, and outer membrane vesicles interact with red blood cells and immune cells, reaching distant organs. This review aims to describe the composition of blood microbiota in healthy individuals and those with disease conditions. Furthermore, special emphasis is placed on the interaction of blood microbiota with host cells to better understand disease mechanisms.

The urogenital microbiome in chronic kidney disease patients on peritoneal dialysis

INTRODUCTION AND OBJECTIVES

Diabetes, dyslipidemia, older age, gender, urinary tract infections, and recent antibiotic intake have been associated with a decrease in the urobiome richness and other fluctuations in this microbiome. Gut and blood microbiome have been reported to be altered in patients with chronic kidney disease (CKD), and specifically in peritoneal dialysis (PD) patients. Still, there are currently no studies describing the urogenital microbiome in CKD-PD patients. In this study we characterized the urobiome profile in 46 PD patients and analyzed its clinical and inflammatory parameters.

MATERIALS AND METHODS

Mid-stream urine, fecal and blood samples were collected from 46 patients undergoing PD at Centro Hospitalar Universitário de São João (CHUSJ) in Porto, Portugal. Exclusion criteria were age under 18 years old, inability to give informed consent, history of infection in the last three months, and antibiotic intake in the last three months. The microbiome communities were analyzed by amplification and sequencing of the V3-V4 region of the bacterial 16S rRNA gene. Correlations with the patients' clinical data and inflammatory profile were performed.

RESULTS

CKD-PD patients presented a unique urobiome profile dominated by Bacillota, Actinomycetota and Pseudomonadota and characterized by a lower Shannon diversity than fecal and blood microbiome. The taxonomic profiles of urogenital samples were organized in multiple subtypes dominated by populations of Lactobacillus, Staphylococcus, Streptococcus, Gardnerella, Prevotella, Escherichia-Shigella, being similar to other non-PD-CKD patients. Gender, sCD14, residual diuresis and history of peritonitis were significantly associated to variations in the urobiome. Although not reaching statistical significance, diabetes and the time on PD also showed association with particular taxonomic groups. Depletion of Gardnerella, Staphylococcus, Corynebacterium, Lactobacillus or Dermabacter populations correlated with CKD-PD patients with history of diabetes, history of peritonitis and altered levels of sCD14.

CONCLUSIONS

Our results highlight urogenital microbiome as a potential partner and/or marker in the overall health state of CKD-PD patients.

Food to Prevent Vascular Calcification in Chronic Kidney Disease

Vascular calcification (VC) is a consequence of chronic kidney disease (CKD) which is of paramount importance regarding the survival of CKD patients. VC is far from being controlled with actual medication; as a result, in recent years, diet modulation has become more compelling. The concept of medical nutritional therapy points out the idea that food may prevent or treat diseases. The aim of this review was to evaluate the influence of food habits and nutritional intervention in the occurrence and progression of VC in CKD. Evidence reports the harmfulness of ultra-processed food, food additives, and animal-based proteins due to the increased intake of high absorbable phosphorus, the scarcity of fibers, and the increased production of uremic toxins. Available data are more supportive of a plant-dominant diet, especially for the impact on gut microbiota composition, which varies significantly depending on VC presence. Magnesium has been shown to prevent VC but only in experimental and small clinical studies. Vitamin K has drawn considerable attention due to its activation of VC inhibitors. There are positive studies; unfortunately, recent trials failed to prove its efficacy in preventing VC. Future research is needed and should aim to transform food into a medical intervention to eliminate VC danger in CKD.

Role of symbiotic microbiota dysbiosis in the progression of chronic kidney disease accompanied with vascular calcification

Background: Chronic kidney disease (CKD) is now globally recognized as a critical public health concern. Vascular calcification (VC) represents a significant risk factor for cardiovascular events in individuals with CKD. It is the accessible and precise diagnostic biomarkers for monitoring the progression of CKD and the concurrent VC are urgently needed. Methods: The adenine diet-induced CKD rat model was utilized to investigate chronic kidney injury, calcification in the kidney and thoracic aorta, and dysregulation of biochemical indices. Enzyme-linked immune sandwich assays were employed to analyze changes in calcification-related proteins. 16S rRNA sequencing was performed to delineate the microbiota characteristics in the gut and blood of CKD-afflicted rats. Additionally, transcriptome sequencing of kidney tissue was conducted to explore the relationship between CKD-associated microbiota features and alterations in kidney function. Results: The adenine diet-induced CKD inhibited body weight gain, and led to kidney injury, and pronounced calcification in kidney and thoracic aorta. The microbiota both in the gut and blood of these affected rats exhibited significantly lower alpha diversity and distinctive beta diversity than those in their healthy counterparts. CKD resulted in dysregulation of several biochemical indices (including elevated levels of creatinine, low-density lipoprotein-cholesterol, sodium, phosphorous, total cholesterol, and urea and decreased levels of albumin, calcium, lactate dehydrogenase, and total bilirubin). Moreover, it upregulated calcification-related factors (bone sialoprotein [BSP], Klotho, fibroblast growth factor [FGF]-23, and sclerostin [SOST]) and lipopolysaccharide (LPS). Notably, the increased Acinetobacter in the blood was positively associated with calcifications in the kidney and thoracic aorta, in addition to the positive correlation with gut microbiota. The enrichment of Acinetobacter was concurrent with increases in calcification factors (BSP, FGF-23, and SOST), LPS, and phosphorous. Furthermore, transcriptome sequencing revealed that the enrichment of Acinetobacter was positively correlated with the majority of upregulated genes and negatively correlated with downregulated genes involved in the mineral absorption pathway. Conclusion: Our findings, for the first time, underscore that dysbiosis of symbiotic microbiota, both in the gut and blood, is involved in the progression of CKD. Particularly, the enrichment of Acinetobacter in blood emerges as a potential risk factor for CKD and its accompanying VC.

Correlation between gut microbiome and cognitive impairment in patients undergoing peritoneal dialysis

BACKGROUND

Growing evidence has demonstrated that patients undergoing peritoneal dialysis (PD) are more likely to experience cognitive impairment than patients with non-dialysis end-stage renal disease (ESRD); however, the underlying mechanisms remain unclear. This study aimed to identify the role and predictive significance of gut microbiome alterations in PD-associated cognitive impairment.

METHODS

A total of 29 non-dialysis ESRD patients and 28 PD patients were enrolled in this study and divided into subgroups according to the Montreal Cognitive Assessment (MoCA). Faecal samples were analyzed using 16 S rRNA. Mini-Mental State Examination (MMSE) and MoCA scores were used to assess the degree of cognitive impairment in patients.

RESULTS

The 16 S rRNA analysis demonstrated differences in gut microbiome abundance and structure between PD and non-dialysis ESRD patients and between PD patients with cognitive impairment (PCI) and PD patients with normal cognition (PNCI). At family and genus levels, Prevotellaceae exhibited the greatest structure difference, while Lactobacillus exhibited the greatest abundance difference between PCI and PNCI. Altered microbiota abundance significantly correlated with cognitive function and serum indicators in PD. In addition, different modules related to fatty acid, lipid, pantothenate, and coenzyme A biosynthesis, and tyrosine and tryptophan metabolism were inferred from 16 S rRNA data between PCI and PNCI. Both groups could be distinguished using models based on the abundance of Lactobacillaceae (Area under curve [AUC] = 0.83), Actinomycetaceae (AUC = 0.798), and Prevotellaceae (AUC = 0.778) families and Lactobacillus (AUC = 0.848) and Actinomyces (AUC = 0.798) genera.

CONCLUSION

Gut microbiome evaluation could aid early cognitive impairment diagnosis in patients undergoing PD.

Relationship between gut microbiota and vascular calcification in hemodialysis patients

INTRODUCTION

Vascular calcification (VC) is an independent risk factor for cardiovascular mortality in end-stage renal disease (ESRD) patients. The pathogenesis of VC is complicated and unclear. Uremic toxins produced by gut microbiota can promote VC. This study aims to identify the differences in gut microbiota between the different VC groups and the main bacteria associated with VC in hemodialysis (HD) patients in an attempt to open up new preventive and therapeutic approaches and define the probable mechanism for VC in HD patients in the future.

METHODS

A total of 73 maintenance HD patients were enrolled in this cross-sectional study. According to the abdominal aortic calcification (AAC) scores, the participants were divided into the high AAC score group and the low AAC score group. High-throughput sequencing of the gut microbiota was performed and the results were evaluated by alpha diversity, beta diversity, species correlation, and model predictive analyses.

RESULTS

The prevalence of VC was 54.79% (40/73) in the study. The majority of phyla in the two groups were the same, including Firmicutes, Actinobacteriota, Proteobacteria, and Bacteroidota. The microbial diversity in the high AAC score group had a decreasing trend (p = 0.050), and the species abundance was significantly lower (p = 0.044) than that in the low AAC score group. The HD patients with high AAC scores showed an increased abundance of Proteobacteria and decreased abundances of Bacteroidota and Synergistota at the phylum level; increased abundances of Escherichia-Shigella, Ruminococcus_gnavus_group, and Lactobacillus; and decreased abundances of Ruminococcus and Lachnospiraceae_NK4A136_group at the genus level (p<0.05). Escherichia-Shigella and Ruminococcus_gnavus_group were positively correlated with VC, and Ruminococcus, Adlercreutzia, Alistipes, and norank_f__Ruminococcaceae were negatively correlated with VC. Escherichia-Shigella had the greatest influence on VC in HD patients, followed by Ruminococcus and Butyricimonas.

CONCLUSIONS

Our results provide clinical evidence that there was a difference in gut microbiota between the different VC groups in HD patients. Escherichia-Shigella, a lipopolysaccharide (LPS)-producing bacterium, was positively correlated with VC and had the greatest influence on VC. Ruminococcus, a short-chain fatty acid (SCFA)-producing bacterium, was negatively correlated with VC and had the second strongest influence on VC in HD patients. The underlying mechanism is worth studying. These findings hint at a new therapeutic target.

Effects of Probiotic-Enriched Minas Cheese (Lactobacillus acidophilus La-05) on Cardiovascular Parameters in 5/6 Nephrectomized Rats

Dairy foods have become an interest in chronic kidney disease (CKD) due to their nutritional profile, which makes them a good substrate for probiotics incorporation. This study evaluated the effect of probiotic-enriched Minas cheese with Lactobacillus acidophilus La-05 in an experimental rat model for CKD on cardiac, inflammatory, and oxidative stress parameters. Male Wistar rats were divided into 4 groups (n = 7/group): 5/6 nephrectomy + conventional Minas cheese (NxC); 5/6 nephrectomy + probiotic Minas cheese (NxPC); Sham + conventional Minas cheese (ShamC); Sham + probiotic Minas cheese (ShamPC). Offering 20 g/day of Minas cheese with Lact. acidophilus La-05 (108-109 log CFU/g) for 6 weeks. The cardiomyocyte diameter was determined. Superoxide dismutase (SOD) activity in plasma, heart, kidney, and colon tissue was performed. At the end of supplementation, no significant changes in lipid profile and renal parameters were found. The NxPC group showed a decrease in cardiomyocyte diameter compared to the NxC group (16.99 ± 0.85 vs. 19.05 ± 0.56 μm, p = 0.0162); also they showed reduced plasmatic SOD activity (502.8 ± 49.12 vs. 599.4 ± 94.69 U/mL, p < 0.0001). In summary, probiotic-enriched Minas cheese (Lact. acidophilus La-05) consumption suggests a promisor cardioprotective effect and was able to downregulate SOD activity in a rat model of CKD.

The gut microbiome tango in the progression of chronic kidney disease and potential therapeutic strategies

Chronic kidney disease (CKD) affects more than 10% population worldwide and becomes a huge burden to the world. Recent studies have revealed multifold interactions between CKD and gut microbiome and their pathophysiological implications. The gut microbiome disturbed by CKD results in the imbalanced composition and quantity of gut microbiota and subsequent changes in its metabolites and functions. Studies have shown that both the dysbiotic gut microbiota and its metabolites have negative impacts on the immune system and aggravate diseases in different ways. Herein, we give an overview of the currently known mechanisms of CKD progression and the alterations of the immune system. Particularly, we summarize the effects of uremic toxins on the immune system and review the roles of gut microbiota in promoting the development of different kidney diseases. Finally, we discuss the current sequencing technologies and novel therapies targeting the gut microbiome.

Molecular Characterisation of Blood Microbiome in Patients with Ankylosing Spondylitis and Healthy Controls

Background

In human and animal studies, ankylosing spondylitis (AS) has been increasingly linked to changes in the microbial inhabitants in the human body (microbiome). These studies have primarily now concentrated on the microbial communities that live in the gastrointestinal tract. However, evidence suggests that various molecular techniques can be used to detect microbial DNA in blood circulation. This DNA might be an unknown reservoir of biomarkers with the potential to track alterations in the microbiomes of remote locations, such as the gut. To this end, we compared the presence and identity of microbial DNA in blood samples taken from ankylosing spondylitis patients to healthy control subjects by amplifying and sequencing the bacterial 16S rRNA variable region four.

Methods

The study's design is a case study based on the presence and identity of bacterial DNA in the blood of Ankylosing spondylitis (AS) patients (n = 10) and healthy control subjects (n = 10) was investigated by amplifying and sequencing the bacterial 16S rRNA gene. Blood concentrations of the cytokines TNF alpha, IL-17A, and IL-23 were determined by the Human Magnetic Luminex Screening, and data were analysed using an Unpaired T-test.

Results

Using PCR amplification, 8 of 10 AS patients (80%) and 8 of 10 healthy control samples (80%) had microbial 16S rRNA in their blood. At the phylum level, Proteobacteria (Control = 48.5%, AS = 52%), Firmicutes (Control = 27.8%, AS = 26.1%), Actinobacteria (Control = 15.4%, AS = 10.7%), and Bacteroidetes (Control = 6.5%, AS = 10%) dominated the blood microbiome. A two-tailed Mann-Whitney test found that Ankylosing Spondylitis was associated with significantly elevated Bacteroides (P < 0.05), Prevotella (P < 0.001), and Micrococcus (P < 0.01), and significantly reduced levels of Corynebacterium 1 (P < 0.001), Gemella (P < 0.01), and Alloprevotella (P < 0.05), compared to healthy controls. Additionally, it was shown that the presence of the Prevotella genus was highly positively correlated with higher levels of TNF-alpha (P < 0.05; r = 0.8) in AS patients' blood.

Conclusion

This article reveals that a blood microbiome exists in healthy individuals and identifies particular taxa modulated in disease. These blood-derived signatures indicate that this field needs more research and may be helpful as disease biomarkers.

Environmental cadmium exposure alters the internal microbiota and metabolome of Sprague-Dawley rats

Cadmium (Cd) is a toxic element that can negatively affect both humans and animals. It enters the human and animal bodies through the respiratory and digestive tracts, following which it tends to accumulate in different organs, thereby seriously affecting human and animal health, as well as hampering social and economic development. Cd exposure can alter the composition of intestinal microbiota. In addition, it can damage the peripheral organs by causing the translocation of intestinal microbiota. However, the relationship between translocation-induced changes in the composition of microbiome in the blood and metabolic changes remains unclear. In the present study, we investigated the effects of Cd exposure on microbiota and serum metabolism in rats by omics analysis. The results demonstrated that Cd exposure disrupted the balance between the blood and intestinal flora in Sprague-Dawley (SD) rats, with a significant increase in gut microbiota (Clostridia_UCG_014, NK4A214_group) and blood microbiome (Corynebacterium, Muribaculaceae). However, Cd exposure caused the translocation of Corynebacterium and Muribaculaceae from the gut into the blood. In addition, Cd exposure was associated with the up-regulation of serum indoxyl sulfate, phenyl sulfate, and p-cresol sulfate; down-regulation of δ-tocopherol and L-glutamine; and changes in blood microbiome and metabolites. In conclusion, we identified novel metabolic biomarkers for Cd toxicity, which will also expand our understanding of the role of blood microbiome in Cd-induced injury.

The Diagnostic Potential of the Human Blood Microbiome: Are We Dreaming or Awake?

Human blood has historically been considered a sterile environment. Recently, a thriving microbiome dominated by Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes phyla was detected in healthy blood. The localization of these microbes is restricted to some blood cell populations, particularly the peripheral blood mononuclear cells and erythrocytes. It was hypothesized that the blood microbiome originates from the skin-oral-gut axis. In addition, many studies have evaluated the potential of blood microbiome dysbiosis as a prognostic marker in cardiovascular diseases, cirrhosis, severe liver fibrosis, severe acute pancreatitis, type 2 diabetes, and chronic kidney diseases. The present review aims to summarize current findings and most recent evidence in the field.

The Gut-Peritoneum Axis in Peritoneal Dialysis and Peritoneal Fibrosis

Peritoneal fibrosis is an important cause of peritoneal dialysis (PD) discontinuation worldwide and is associated with high morbidity and mortality rate. Although the era of metagenomics has provided new insights into the interactions between the gut microbiota and fibrosis in various organs and tissues, its role in peritoneal fibrosis has rarely been discussed. This review provides a scientific rationale and points out the potential role of gut microbiota in peritoneal fibrosis. In addition, the interaction between the gut, circulatory, and peritoneal microbiota is highlighted, with an emphasis on the relationship to PD outcomes. More research is needed to elucidate the mechanisms underlying the role of gut microbiota in peritoneal fibrosis and potentially unveil new target options for the management of PD technique failure.

The Blood Microbiome and Health: Current Evidence, Controversies, and Challenges

Blood is conventionally thought to be sterile. However, emerging evidence on the blood microbiome has started to challenge this notion. Recent reports have revealed the presence of genetic materials of microbes or pathogens in the blood circulation, leading to the conceptualization of a blood microbiome that is vital for physical wellbeing. Dysbiosis of the blood microbial profile has been implicated in a wide range of health conditions. Our review aims to consolidate recent findings about the blood microbiome in human health and to highlight the existing controversies, prospects, and challenges around this topic. Current evidence does not seem to support the presence of a core healthy blood microbiome. Common microbial taxa have been identified in some diseases, for instance, Legionella and Devosia in kidney impairment, Bacteroides in cirrhosis, Escherichia/Shigella and Staphylococcus in inflammatory diseases, and Janthinobacterium in mood disorders. While the presence of culturable blood microbes remains debatable, their genetic materials in the blood could potentially be exploited to improve precision medicine for cancers, pregnancy-related complications, and asthma by augmenting patient stratification. Key controversies in blood microbiome research are the susceptibility of low-biomass samples to exogenous contamination and undetermined microbial viability from NGS-based microbial profiling, however, ongoing initiatives are attempting to mitigate these issues. We also envisage future blood microbiome research to adopt more robust and standardized approaches, to delve into the origins of these multibiome genetic materials and to focus on host-microbe interactions through the elaboration of causative and mechanistic relationships with the aid of more accurate and powerful analytical tools.

The Related Metabolic Diseases and Treatments of Obesity

Obesity is a chronic disease characterized by the abnormal or excessive accumulation of body fat, affecting more than 1 billion people worldwide. Obesity is commonly associated with other metabolic disorders, such as type 2 diabetes, non-alcoholic fatty liver disease, cardiovascular diseases, chronic kidney disease, and cancers. Factors such as a sedentary lifestyle, overnutrition, socioeconomic status, and other environmental and genetic conditions can cause obesity. Many molecules and signaling pathways are involved in the pathogenesis of obesity, such as nuclear factor (NF)-κB, Toll-like receptors (TLRs), adhesion molecules, G protein-coupled receptors (GPCRs), programmed cell death 1 (PD-1)/programmed death-ligand 1 (PD-L1), and sirtuin 1 (SIRT1). Commonly used strategies of obesity management and treatment include exercise and dietary change or restriction for the early stage of obesity, bariatric surgery for server obesity, and Food and Drug Administration (FDA)-approved medicines such as semaglutide and liraglutide that can be used as monotherapy or as a synergistic treatment. In addition, psychological management, especially for patients with obesity and distress, is a good option. Gut microbiota plays an important role in obesity and its comorbidities, and gut microbial reprogramming by fecal microbiota transplantation (FMT), probiotics, prebiotics, or synbiotics shows promising potential in obesity and metabolic syndrome. Many clinical trials are ongoing to evaluate the therapeutic effects of different treatments. Currently, prevention and early treatment of obesity are the best options to prevent its progression to many comorbidities.