Circulating Concentrations of Vitamin B6 and Kidney Cancer Prognosis: A Prospective Case-Cohort Study

Delivery of exogenous miR-19b by Wharton's Jelly Mesenchymal Stem Cells attenuates transplanted kidney ischemia/reperfusion injury by regulating cellular metabolism

Renal ischemia-reperfusion injury (IRI) frequently occurs following kidney transplantation, and exosomes derived from umbilical cord mesenchymal stem cells (WJ-MSC-Exos) have shown promise in treating IRI in transplanted kidneys. Our study delved into the potential mechanism of WJ-MSC-Exos in ameliorating IRI in transplanted kidneys, revealing that miR-19b is abundantly present in WJ-MSC-Exos. Both in vivo and in vitro experiments demonstrated that the absence of miR-19b abolished the protective effects of WJ-MSC-Exos against renal IRI. Mechanistically, miR-19b suppressed glycogen synthase kinase-3β (GSK3β) expression, thereby stabilizing PDXK protein through direct binding. Treatment with WJ-MSC-Exos led to reduced PDXK levels and enhanced pyridoxine accumulation, ultimately mitigating IRI in transplanted kidneys and I/R-induced HK2 cell apoptosis. These findings elucidate the underlying mechanism of WJ-MSC-Exos in alleviating IRI in transplanted kidneys, unveiling novel therapeutic targets for post-kidney transplantation IRI and providing a solid theoretical foundation for the clinical application of WJ-MSC-Exos in IRI treatment post-transplantation.

Relationship of Low Vitamin B6 Status with Sarcopenia, Frailty, and Mortality: A Narrative Review

Marginal vitamin B6 (B6) deficiency is a widespread global concern. Inadequate B6 levels have been linked to an increased risk of age-related chronic diseases such as cardiovascular diseases and cancers. In recent years, the growing concern over sarcopenia (the age-related loss of muscle mass and strength) and frailty (a decline in physiological resilience and increased vulnerability associated with aging) is particularly relevant due to the emergence of super-aged societies in developed countries. Notably, among the thirty-one studies included in this review, twenty-five showed a significant association of B6 status with sarcopenia, frailty, and all-cause mortality in adults (p < 0.05), while six showed no association. Emerging studies have suggested novel mechanisms underlying this association. These mechanisms involve P2X7 receptor-mediated NLRP3 inflammasome signaling, AMPK signaling, PD-L1 signaling, and satellite cell-mediated myogenesis. Furthermore, the modulation of PLP-dependent enzymes due to B6 deficiency is associated with impaired metabolic processes, affecting energy utilization, imidazole peptide production, and hydrogen sulfide production, as well as the kynurenine pathway, all of which play vital roles in skeletal muscle health and pathophysiology. This narrative review provides an up-to-date assessment of our current understanding of the potential role of nutritional B6 status in combating sarcopenia, frailty, and mortality.

Circulating pyridoxal 5′-phosphate in serum and whole blood: implications for assessment of vitamin B6 status

Objectives

Concentrations of pyridoxal 5′-phosphate (PLP) in serum and whole blood are routinely measured. The suitability of these markers in capturing vitamin B6 insufficiency is not well studied.

Methods

In 212 subjects, concentrations of PLP and thiamine pyrophosphate (TPP) were simultaneously measured in EDTA-whole blood using Chromsystems® (52052) method on HPLC devices. The whole blood PLP concentrations were compared to serum PLP concentrations measured using reagents from Immundiagnostik® (KC 2100). The whole blood TPP concentrations measured with the Chromsystems® (52052) were compared to those measured by the Chromsystems® (35000) method. Concentrations of homocysteine (tHcy) and cystathionine (Cys) were measured and used to judge the PLP methods.

Results

Serum PLP concentrations were on average 41% lower than whole blood PLP [mean (SD)=55.4 (83.0) vs. 131 (217) nmol/L]. Serum and whole blood PLP showed a strong correlation [Pearson correlation coefficient=0.724, p<0.001, n=204]. Eighty-five samples showed discrepant results for PLP status (serum PLP ≤30 nmol/L, but whole blood PLP >51 nmol/L) while 102 samples showed coherent results (reference group). The discrepancy group showed higher odds ratio for elevated tHcy >12.0 μmol/L compared to the reference group [OR (95% confidence intervals, CI)=2.1 (1.2–4.0)]. The OR (95% CI) of elevated Cys >300 nmol/L was 1.9 (1.0–3.5) in the discrepancy group compared to the reference group. TPP concentrations were 6% lower when using the Chromsystems®, 52052 compared to levels measured with Chromsystems®, 35000.

Conclusions

Serum and whole blood PLP concentrations disagree in a substantial number of samples. Serum PLP was better in reflecting elevated tHcy and Cys compared to whole blood PLP. Whole blood PLP underestimates the prevalence of vitamin B6 insufficiency. Methods of measuring TPP concentrations in whole blood were exchangeable.

Diagnosing, Typing, and Staging of Renal Cell Carcinoma by Designer Matrix-Based Urinary Metabolic Analysis

Molecular diagnosing, typing, and staging have been considered to be the ideal alternatives of imaging-based detection methods in clinics. Designer matrix-based analytical tools, with high speed, throughout, efficiency and low/noninvasiveness, have attracted much attention recently for in vitro metabolite detection. Herein, we develop an advanced metabolic analysis tool based on highly porous metal oxides derived from available metal-organic frameworks (MOFs), which elaborately inherit the morphology and porosity of MOFs and newly incorporate laser adsorption capacity of metal oxides. Through optimized conditions, direct high-quality fingerprinting spectra in 0.5 μL of urine are acquired. Using these fingerprinting spectra, we can discriminate the renal cell carcinoma (RCC) from healthy controls with higher than 0.99 of area under the curve (AUC) values (R²Y(cum) = 0.744, Q² (cum) = 0.880), as well, from patients with other tumors (R²Y(cum) = 0.748, Q²(cum) = 0.871). We also realize the typing of three RCC subtypes, including clear cell RCC, chromophobe RCC (R²Y(cum) = 0.620, Q²(cum) = 0.656), and the staging of RCC (R²Y(cum) = 0.755, Q²(cum) = 0.857). Moreover, the tumor sizes (threshold value is 3 cm) can be remarkably recognized by this advanced metabolic analysis tool (R²Y(cum) = 0.710, Q²(cum) = 0.787). Our work brings a bright prospect for designer matrix-based analytical tools in disease diagnosis, typing and staging.

Associations of Serum Vitamin B6 Status and Catabolism With All-Cause Mortality in Patients With T2DM

CONTEXT

There is little evidence regarding the association between serum vitamin B6 status and catabolism and all-cause mortality in patients with type-2 diabetes mellitus (T2DM).

OBJECTIVE

We aimed to ascertain if the serum level of vitamin B6 and catabolism, including pyridoxal 5'-phosphate (PLP) and 4-pyridoxic acid (4-PA), were associated with risk of all-cause mortality in T2DM patients.

METHODS

This prospective cohort study involved 2574 patients with T2DM who participated in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2010. The serum concentrations of PLP and 4-PA were used to assess the serum level of vitamin B6. Mortality status was determined by routine follow-up using the National Death Index through December 31, 2015.

RESULTS

Over a median follow-up of 85 months, there were 588 deaths. The fully adjusted Cox model indicated that the highest serum PLP concentrations (> 63.6 nmol/L) were associated with a decrease in all-cause mortality (hazard ratio [HR], 0.74; 95% CI, 0.55-0.99, P trend = .035). The risk for all-cause mortality was 59% higher for participants with the highest quartile of 4-PA level compared with the lowest quartile (HR, 1.62; 95% CI, 1.12-2.35; P trend = .003). The sensitivity and specificity of the combination of PLP and 4-PA levels for the prediction of all-cause mortality were 59.5% and 60.9%, respectively (area under the receiver operating characteristic curve = 0.632). The Kaplan-Meier method was used to estimate overall survival for patients based on different combinations of PLP level and 4-PA level. Patients with PLP less than 24.3 nmol/L and 4-PA greater than or equal to 25.4 nmol/L had the worst outcomes (log-rank P < .001).

CONCLUSION

Overall, our data suggest that a low serum level of PLP and high serum level of 4-PA, which represent the serum level of vitamin B6, increases the risk of all-cause mortality significantly in patients with T2DM.

Association of Serum Vitamin B6 with All-Cause and Cause-Specific Mortality in a Prospective Study

There is little evidence regarding the association between serum vitamin B6 concentration and subsequent mortality. We aimed to evaluate the association of serum vitamin B6 concentration with all-cause, cardiovascular disease (CVD), and cancer mortality in the general population using data from the National Health and Nutrition Examination Survey (NHANES). Our study examined 12,190 adults participating in NHANES from 2005 to 2010 in the United States. The mortality status was linked to National Death Index (NDI) records up to 31 December 2015. Pyridoxal 5′-phosphate (PLP) is the biologically active form of vitamin B6. Vitamin B6 status was defined as deficient (PLP < 20 nmol/L), insufficient (PLP ≥ 20.0 and <30.0 nmol/L), and sufficient (PLP ≥ 30.0 nmol/L). We established Cox proportional-hazards models to estimate the associations of categorized vitamin B6 concentration and log-transformed PLP concentration with all-cause and cause-specific mortality by calculating hazard ratios (HRs) and 95% confidence intervals (95%CIs). In our study, serum vitamin B6 was sufficient in 70.6% of participants, while 12.8% of the subjects were deficient in vitamin B6. During follow-up, a total of 1244 deaths were recorded, including 294 cancer deaths and 235 CVD deaths. After multivariate adjustment in Cox regression, participants with higher serum vitamin B6 had a 15% (HR = 0.85, 95%CI = 0.77, 0.93) reduced risk of all-cause mortality and a 19% (HR = 0.81, 95%CI = 0.68, 0.98) reduced risk for CVD mortality for each unit increment in natural log-transformed PLP. A higher log-transformed PLP was not significantly associated with a lower risk for cancer mortality. Compared with sufficient vitamin B6, deficient (HR = 1.37, 95%CI = 1.17, 1.60) and insufficient (HR = 1.19, 95%CI = 1.02, 1.38) vitamin B6 level were significantly associated with a higher risk for all-cause mortality. There was no significant association for cause-specific mortality. Participants with higher levels of vitamin B6 had a lower risk for all-cause mortality. These findings suggest that maintaining a sufficient level of serum vitamin B6 may lower the all-cause mortality risk in the general population.

Untargeted Metabolomics Reveals the Protective Effect of a Traditional Chinese Herbal Decoction on Cisplatin-Induced Acute Kidney Injury

Our previous studies have demonstrated that Jian-Pi-Yi-Shen formula (JPYSF), a traditional Chinese herbal decoction, has a renoprotective effect in 5/6 nephrectomy-induced chronic kidney injury. However, the role and potential mechanisms of JPYSF in the treatment of acute kidney injury (AKI) remain unknown. This study was designed to test the beneficial effect of JPYSF in an AKI mouse model and to investigate the underlying mechanism by using metabolomics analysis. The AKI mouse model was induced by a single intraperitoneal injection of cisplatin at a dose of 20 mg/kg. The mice in the treatment group were pretreated orally with JPYSF (18.35 g/kg/d) for 5 days before cisplatin injection. Seventy-two hours after cisplatin injection, serum and kidney samples were collected for biochemical and histological examination. Ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS) was applied to analyze metabolic profiling variations in the kidney. The results showed that pretreatment with JPYSF obviously reduced the levels of serum creatinine and blood urea nitrogen and alleviated renal pathological injury in AKI mice. Orthogonal partial least-squares discriminant analysis (OPLS-DA) score plot revealed a clear separation between the AKI and AKI + JPYSF group. A total of 68 and 87 significantly differentially expressed metabolites were identified in the kidney of AKI mice responding to JPYSF treatment in negative and positive ion mode, respectively. The pivotal pathways affected by JPYSF included vitamin B6 metabolism, alanine, aspartate and glutamate metabolism, lysine biosynthesis, and butanoate metabolism. In conclusion, JPYSF can protect the kidney from cisplatin-induced AKI, which may be associated with regulating renal metabolic disorders.

Large-scale genome-wide screening of circulating microRNAs in clear cell renal cell carcinoma reveals specific signatures in late-stage disease

Circulating miRNAs have shown great promises as noninvasive diagnostic and predictive biomarkers in several solid tumors. While the miRNA profiles of renal tumors have been extensively explored, knowledge of their circulating counterparts is limited. Our study aimed to provide a large-scale genome-wide profiling of plasma circulating miRNA in clear-cell renal cell carcinoma (ccRCC). Plasma samples from 94 ccRCC cases and 100 controls were screened for 754 circulating micro-RNAs (miRNA) by TaqMan arrays. Analyses including known risk factors for renal cancer-namely, age, sex, hypertension, obesity, diabetes, tobacco smoking and alcohol consumption-highlighted that circulating miRNA profiles were tightly correlated with the stage of the disease. Advanced tumors, characterized as stage III and IV, were associated with specific miRNA signatures that significantly differ from both controls and earlier stage ccRCC cases. Molecular pathway enrichment analyses of their gene targets showed high similarities with alterations observed in renal tumors. Plasma circulating levels of miR-150 were significantly associated with RCC-specific survival and could marginally improve the predictive accuracy of clinical parameters in our series, including age at diagnosis, sex and conventional staging. In summary, our results suggest that circulating miRNAs may provide insights into renal cell carcinoma progression.

Inflammation, vitamin B6 and related pathways

The active form of vitamin B6, pyridoxal 5'-phosphate (PLP), serves as a co-factor in more than 150 enzymatic reactions. Plasma PLP has consistently been shown to be low in inflammatory conditions; there is a parallel reduction in liver PLP, but minor changes in erythrocyte and muscle PLP and in functional vitamin B6 biomarkers. Plasma PLP also predicts the risk of chronic diseases like cardiovascular disease and some cancers, and is inversely associated with numerous inflammatory markers in clinical and population-based studies. Vitamin B6 intake and supplementation improve some immune functions in vitamin B6-deficient humans and experimental animals. A possible mechanism involved is mobilization of vitamin B6 to the sites of inflammation where it may serve as a co-factor in pathways producing metabolites with immunomodulating effects. Relevant vitamin B6-dependent inflammatory pathways include vitamin B6 catabolism, the kynurenine pathway, sphingosine 1-phosphate metabolism, the transsulfuration pathway, and serine and glycine metabolism.