Correlations between plasma strontium concentration, components of calcium and phosphate metabolism and renal function in type 2 diabetes mellitus

The correlation of urinary strontium with the risk of chronic kidney disease among the general United States population

Background

This study sought to illustrate whether urinary strontium levels were related to developing chronic kidney disease (CKD) in the United States population.

Methods

A total of 5,005 subjects were identified from the National Health and Nutrition Examination Survey 2011-2016. Survey-weighted logistic regression analysis, multivariate linear regression analysis, restricted cubic spline (RCS) plots curve and stratified analyses were undertaken to explicate the correlation between urinary strontium and CKD.

Results

With the increase of urinary strontium, the incidence rate of CKD and urinary albumin to creatinine ratio (UACR) levels gradually decreased, and estimated glomerular filtration rate (eGFR) levels gradually increased. After controlling all confounders, only urinary strontium in the fourth quartile was correlated to a lower CKD prevalence (OR: 0.59; 95% CI, 0.44-0.79) compared to the lowest quartile. Multivariate linear regression analysis showed that urinary strontium was positively correlated with eGFR but negatively with UACR. RCS curve suggested a nonlinear relationship between urinary strontium and CKD (P for non-linearity <0.001). Stratified analyses indicated no significant difference in the correlation between urinary strontium and CKD among different subgroups.

Conclusion

Urinary strontium was strongly correlated with a low risk of CKD, and this association was non-linear among the US population.

Impact of claudin-10 deficiency on amelogenesis: Lesson from a HELIX tooth

In epithelia, claudin proteins are important components of the tight junctions as they determine the permeability and specificity to ions of the paracellular pathway. Mutations in CLDN10 cause the rare autosomal recessive HELIX syndrome (Hypohidrosis, Electrolyte imbalance, Lacrimal gland dysfunction, Ichthyosis, and Xerostomia), in which patients display severe enamel wear. Here, we assess whether this enamel wear is caused by an innate fragility directly related to claudin-10 deficiency in addition to xerostomia. A third molar collected from a female HELIX patient was analyzed by a combination of microanatomical and physicochemical approaches (i.e., electron microscopy, elemental mapping, Raman microspectroscopy, and synchrotron-based X-ray fluorescence). The enamel morphology, formation time, organization, and microstructure appeared to be within the natural variability. However, we identified accentuated strontium variations within the HELIX enamel, with alternating enrichments and depletions following the direction of the periodical striae of Retzius. These markings were also present in dentin. These data suggest that the enamel wear associated with HELIX may not be related to a disruption of enamel microstructure but rather to xerostomia. However, the occurrence of events of strontium variations within dental tissues might indicate repeated episodes of worsening of the renal dysfunction that may require further investigations.

Co-exposure to perfluoroalkyl acids and heavy metals mixtures associated with impaired kidney function in adults: A community-based population study in China

BACKGROUND

Previous studies have separately linked either perfluoroalkyl acid (PFAA) or heavy metal exposure with kidney dysfunction. However, the relationships of co-exposure to PFAAs and heavy metals with kidney function are still unclear.

OBJECTIVES

To explore the associations between exposure to PFAAs and heavy metals mixtures and kidney function in adults.

METHODS

We conducted a cross-sectional community-based population study in Guangzhou, China, enrolling 1312 adults from November 2018 to August 2019. We quantified 13 PFAAs in serum and 14 heavy metals in plasma. We chose estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD) as outcomes of interest. Distributed lag non-linear models (DLNMs) were used to check nonlinearity of individual pollutant with kidney function. Joint associations of pollutant mixtures on kidney function were assessed by Bayesian Kernel Machine Regression (BKMR) models. We further explored modification effects of gender.

RESULTS

Most individual PFAA and heavy metal were associated with declined kidney function in single-pollutant models. We also observed significant dose-response relationships of pollutant mixtures with reduced eGFR levels and increased odds of CKD in BKMR models. Perfluoroheptanesulfonic acid (PFHpS), arsenic (As) and strontium (Sr) were the predominant contributors among pollutant mixtures. A change in log PFHpS, As and Sr concentrations from the 25th to the 75th percentile were associated with a decrease in eGFR of -5.42 (95% confidence interval (CI): -6.86, -3.98), -2.14 (95% CI: -3.70, -0.58) and -1.87 (95% CI: -3.03, -0.72) mL/min/1.73 m², respectively, when other pollutants were at their median values. In addition, the observed associations were more obvious in females.

CONCLUSIONS

We provided new evidence that co-exposure to PFAAs and heavy metals mixtures was associated with reduced kidney function in adults and PFHpS, As and Sr appeared to be the major contributors. Further studies are warranted to confirm our findings and elucidate the underlying mechanisms.

Novel Cardiovascular Risk Factors in Patients with Diabetic Kidney Disease

Patients with diabetic kidney disease (DKD) are at very high risk for cardiovascular events. Only part of this increased risk can be attributed to the presence of diabetes mellitus (DM) and to other DM-related comorbidities, including hypertension and obesity. The identification of novel risk factors that underpin the association between DKD and cardiovascular disease (CVD) is essential for risk stratification, for individualization of treatment and for identification of novel treatment targets.In the present review, we summarize the current knowledge regarding the role of emerging cardiovascular risk markers in patients with DKD. Among these biomarkers, fibroblast growth factor-23 and copeptin were studied more extensively and consistently predicted cardiovascular events in this population. Therefore, it might be useful to incorporate them in risk stratification strategies in patients with DKD to identify those who would possibly benefit from more aggressive management of cardiovascular risk factors.

Plasma metals and cardiovascular disease in patients with type 2 diabetes

BACKGROUND

Metals exposure from natural environment and pollution have been linked to cardiovascular disease (CVD). However, whether associations existing between plasma multiple metals and incident cardiovascular disease in patients with type 2 diabetes (T2D) is unknown.

OBJECTIVES

We conducted a prospective cohort study to investigate whether plasma levels of metals are associated with incident CVD risk in patients with T2D.

METHODS

In a prospective study of 3897 type 2 diabetes embedded in the Dongfeng-Tongji cohort, fasting blood samples were collected in 2008 at baseline and in 2013 in the first follow-up period. Plasma concentrations of 23 metals were measured by inductively coupled plasma mass spectrometry (ICP-MS). The associations between plasma metal concentrations and CVD risk in patients with T2D were investigated with Cox proportional hazards models.

RESULTS

During an average of 6.2 years follow-up, 1114 participants developed CVD. In the single-metal models adjusting for established cardiovascular risk factors, plasma zinc and selenium levels were negatively and strontium was positively associated with incident CVD risk in patients with T2D. Similar results were obtained in the multiple-metal model, the HRs (95% CIs) for zinc, selenium, and strontium comparing extreme quartiles were 0.78 (95% CI: 0.65-0.93; P trend = 0.011), 0.76 (95% CI: 0.64-0.91; P trend = 0.001), and 1.51 (95% CI: 1.26-1.81; P trend <0.001), respectively. In the joint association analyses of two metals, individuals with high plasma levels of zinc and selenium had significantly lower risk of incident CVD in patients with T2D than those with low levels (HR = 0.77, 95% CI: 0.65-0.91).

CONCLUSIONS

The present study suggested that plasma levels of zinc and selenium had an inverse association with incident CVD risk in patients with T2D, while strontium had a positive correlation. Plasma zinc and selenium combinedly decreased incident CVD risk in patients with T2D. Further research is still needed to verify these findings in other populations.

Increased serum strontium levels and altered oxidative stress status in early-onset preeclampsia

BACKGROUND

Correctly distinguishing preeclampsia (PE), gestational hypertension (GH), and intrauterine growth retardation (IUGR) is a challenge for clinicians due to existing similarities. In our previous study, we showed that serum strontium (Sr) levels were elevated in preeclamptic women compared to healthy and GH pregnant women at the end of pregnancy. The main aim of this study was to evaluate Sr and oxidative stress in PE at the time of symptoms onset and before and compare it with IUGR/GH.

METHODS

Samples collected at symptoms onset included 77 preeclamptic women and 72 women diagnosed with IUGR/GH divided into two groups according to the gestational extraction week (<34 and ≥ 34). Fifteen patients were also serialized until delivery. Samples collected before symptoms onset included 140 women who developed early-onset PE (E-PE, n = 9), late-onset PE (L-PE, n = 13), IUGR (n = 9), GH (n = 32) and no pathologies (n = 77). Strontium, placental growth factor (PlGF), soluble fms-like tyrosine kinase 1 (sFlt-1), uric acid (UA), creatinine, lipid peroxidation, and total antioxidant activity (TAA) were measured.

RESULTS

Mean Sr, sFlt-1/PIGF ratio, UA, and lipid peroxidation/TAA ratio levels were significantly higher (p = 0.002, <0.0001, <0.0001 and = 0.03, respectively) and estimated glomerular filtration rate (eGFR) and TAA significantly lower (p = 0.0008 and < 0.0001, respectively) in E-PE vs other pathologies when gestational extraction week was <34. There was a significant correlation between Sr and eGFR (r = 0.43, p = 0.02), sFlt-1/PIGF ratio (r = 0.56, p = 0.002), TAA and gestational week of sampling (r = -0.45, p = 0.02) and UA (r = -0.82, p < 0.0001) in the E-PE serial samples. No differences were found in Sr levels before symptoms onset.

CONCLUSION

Serum Sr concentration and oxidative status are increased in E-PE when compared to other pathologies at the time of symptoms onset. More studies are needed to elucidate the causes of Sr levels elevation and its role in the pathophysiology of PE.