Low nephron endowment increases susceptibility to renal stress and chronic kidney disease

Chemical and in vivo analyses of calcium silicate-based materials in bone and connective tissues

AIM

Calcium silicate-based cements have been widely used in dentistry mainly due to their physicochemical and biological properties. Commercially available materials use radiopacifiers containing metals (bismuth, tantalum, tungsten and/or zirconium). To investigate volumetric changes, in vivo biocompatibility and systemic migration from eight commercially available materials, including powder/liquid and 'ready-to-use' presentations.

METHODOLOGY

After characterization, tubes were implanted in healthy Wistar rats' alveolar bone and subcutaneous tissues. Micro-CT was used to evaluate volumetric change before/after 30 days of implantation. Histological and immunohistochemistry analysis were used to evaluate materials' biocompatibility. After euthanasia, kidney samples were retrieved, acidic digested and evaluated by inductively coupled plasma mass spectrometry (ICP-MS) for bismuth, tantalum, tungsten and zirconium mass fractions. Statistical analysis compared the results for normality and comparisons adopted a level of significance of 0.05.

RESULTS

Characterization photomicrographs and spectroscopy analysis revealed calcium, silicon and radiopacifiers for tested cements. Volumetric changes after implantation showed higher alteration in subcutaneous tissues than alveolar bone indicating that Biodentine, EndoSequence BC RRM Putty and ProRoot MTA were the most stable materials. Histological analysis found intense inflammation for NeoPUTTY and moderate for the other materials; osteocalcin and osteopontin were positively marked for all materials. Despite its volumetric stability, ProRoot MTA showed a 1000-fold higher mass fraction of bismuth accumulation and MTA Repair HP a 37-fold higher tungsten accumulation in kidney samples when compared with the nonexposed controls. All tantalum-analysed samples indicated a similar mass fraction with the nonexposed controls. Biodentine exhibited a significant lower kidney mass fraction of zirconium accumulation when compared with this control.

CONCLUSIONS

Volumetric analysis revealed that Bio-C Repair, NeoPUTTY and MTA Repair HP presented greater volumetric loss when implanted in the subcutaneous tissue. NeoPUTTY presented more intense inflammatory infiltrate. Systemic migration analysis highlighted the predominance of bismuth in the ProRoot MTA group. These results suggest that endodontic repair cements are affected by their chemical composition, the type of implant tissue and different clinical settings.

Physicochemical properties and biological interaction of calcium silicate-based sealers - in vivo model

OBJECTIVES

To investigate volumetric changes, in vivo biocompatibility, and systemic migration from eight commercial endodontic sealer materials in paste/paste, powder/liquid, and pre-mixed forms.

MATERIALS AND METHODS

The sealers AH Plus Bioceramic, AH Plus Jet, BioRoot RCS, MTApex, Bio-C Sealer, Bio-C Sealer Ion+, EndoSequence BC Sealer and NeoSEALER Flo were studied. After characterisation by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and X-ray diffractometry (XRD), tubes were implanted in Wistar rats' alveolar bone and subcutaneous tissues. Micro-CT evaluated volumetric changes pre/post 30 days of implantation. Histological and immunohistochemistry analyses assessed biocompatibility. Kidney samples underwent spectrometry (ICP-MS) for tantalum, tungsten and zirconium. Statistical analysis determined normality and significance (udp < 0.05).

RESULTS

Characterisation revealed calcium, silicon, and radiopacifiers in the materials. Volumetric changes showed greater alteration in subcutaneous tissues than alveolar bone; BioRoot RCS and MTApex (powder/liquid) were most stable. Histological analysis indicated intense inflammation for AH Plus Jet, moderate for others; IL-10 was marked positively for all materials. AH Plus Jet had an 18-fold higher tungsten and a 37-fold higher zirconium mass fraction in kidneys versus controls, while tantalum showed lower accumulation patterns.

CONCLUSION

Root canal filling materials' responses varied by implantation site and form, demonstrating acceptable biocompatibility. Tantalum and zirconium oxide radiopacifiers appear systemically safe; tungsten-based radiopacifiers are unsuitable due to metal accumulation risks.

CLINICAL RELEVANCE

This study highlights the need for further in vivo studies on endodontic sealers' chemical, biological, and physical behaviors and their systemic migration.

In utero, childhood, and adolescence tobacco smoke exposure, physical activity, and chronic kidney disease incidence in adulthood: evidence from a large prospective cohort study

BACKGROUND

The adverse effects of early-life tobacco smoke exposure on chronic kidney disease (CKD) risk remain unclear. This study aimed to investigate the associations of early-life tobacco smoke exposure with CKD incidence in adulthood, and further explore the modification effects of physical activity (PA).

METHODS

A total of 352,883 participants were included from the UK Biobank. The information on early-life tobacco smoke exposure was assessed by employing in utero tobacco smoke exposure and age of smoking initiation. Weekly moderate-to-vigorous physical activity (MVPA) was calculated for each individual. Cox proportional hazard regression was fitted to estimate the hazard ratio (HR) and 95% confidence interval (CI) of CKD risk, and to investigate the modification effects of MVPA.

RESULTS

CKD incidence significantly increased in participants with in utero tobacco smoke exposure (HR: 1.08, 95% CI: 1.04, 1.12). Compared with never-smokers, we found a monotonic increase in the risk of CKD with smoking initiation across adulthood (HR: 1.21, 95% CI: 1.16, 1.27), adolescence (HR: 1.29, 95% CI: 1.24, 1.35), and childhood (HR: 1.34, 95% CI: 1.25, 1.43) (P trend < 0.001). Additionally, we identified joint cumulative effects of MVPA and early-life tobacco smoke exposure on incident CKD. Compared with never-smokers with recommended MVPA, prenatal or childhood tobacco smokers without recommended MVPA had the highest CKD risk, and the HRs (95% CIs) were 1.17 (1.10, 1.24) and 1.51 (1.36, 1.68), respectively.

CONCLUSIONS

Early-life tobacco smoke exposure may contribute to CKD incidence in adulthood, and the observed associations could be modified by MVPA. These findings provide important information on CKD prevention in the participant's early life while urging a more rapid and powerful need for tobacco control among pregnant couples, children, and adolescents.

Role of metabolic dysfunction-associated steatotic liver disease and of its genetics on kidney function in childhood obesity

OBJECTIVES

Evidence linked metabolic associated steatotic liver disease (MASLD) to kidney damage with the potential contribution of the I148M variant of the Patatin-like phospholipase containing domain 3 (PNPLA3) gene. We aimed at investigating the relationship of MASLD and of its genetics with kidney function in children with obesity.

METHODS

A comprehensive evaluation including genotyping for the I148M PNPLA3 polymorphism was performed in 1037 children with obesity. Fatty liver (FL) was assessed by liver ultrasound. According to MASLD criteria, subjects with obesity but without FL were included in group 1, while patients with obesity and FL (encompassing one MASLD criterion) were clustered into group 2. Group 3 included patients with obesity, FL, and metabolic dysregulation (encompassing >1 MASLD criterion).

RESULTS

Alanine transaminase levels significantly increased while estimated glomerular filtration rate (eGFR) significantly reduced from group 1 to 3. Group 3 showed a higher percentage of carriers of the I148M allele of the PNPLA3 gene compared to other groups (p < 0.0001). Carriers of group 2 and of group 3 showed reduced eGFR levels than noncarriers of group 2 (p = 0.04) and of group 3 (p = 0.02), respectively. A general linear model for eGFR variance in the study population showed an inverse association of eGFR with both MASLD and PNPLA3 genotypes (p = 0.011 and p = 0.02, respectively). An inverse association of eGFR with MASLD was also confirmed only in carriers (p = 0.006).

CONCLUSIONS

The coexistence of more than 1 MASLD criterion in children with obesity seems to adversely affect kidney function. The PNPLA3 I148M allele further impacts on this association.

Urine sodium concentration and 28-day weight velocity in preterm infants: A retrospective cohort study

BACKGROUND

Urine sodium concentration has been suggested as a marker to guide enteral sodium supplementation in preterm infants; however, no previous data have demonstrated relationships between urine sodium concentration and postnatal growth.

METHODS

We performed a single-center retrospective cohort study on 224 preterm infants admitted to the neonatal intensive care unit at the Children's Hospital of Georgia between January 2010 and July 2022. Spot urine sodium was measured in preterm infants (<34 weeks postmenstrual age [PMA]) between days of life (DOLs) 7 and 28. Our exposure of interest was spot urine sodium concentration (milliequivalents per liter) obtained between postnatal days 7 and 28, and our primary outcome was weight velocity (grams per kilograms per day) determined at DOL 28. Statistical relationships were assessed by multivariate analysis with subgroup comparisons by Student t test and analysis of variance.

RESULTS

In 224 preterm infants (199 ± 17 days, 56% male, 71% Black), urine sodium concentration did not associate with weight velocity at DOL 28 and 36 weeks PMA. Urine sodium concentration was weakly associated with gestational age at birth, and Black preterm infants had higher urine sodium values when compared with "other," but not White preterm infants.

CONCLUSION

Spot urine sodium during the first month of life does not associate with weight velocity at DOL 28 or 36 weeks PMA.

Association of Preterm Birth with Adverse Glomerular Disease Outcomes in Children and Adults

Key Points

Preterm birth was a risk factor for adverse outcomes in this heterogeneous cohort of children and adults with glomerular disease. In analyses adjusted for diagnosis and apolipoprotein L1 risk status, there was less remission and faster progression of kidney disease in those born preterm. A novel finding from this study is that adults born preterm were more likely to have an apolipoprotein L1 high-risk genotype.

Background

While some studies of children with nephrotic syndrome have demonstrated worse outcomes in those born preterm compared with term, little data exist on associations of preterm birth with outcomes in adult-onset glomerular disease. Cardiovascular outcomes in those born preterm with glomerular disease are unknown.

Methods

We performed a cross-sectional and longitudinal analysis of participants in the Cure Glomerulonephropathy cohort. Preterm (<37 weeks' gestation) was compared with term (≥37 weeks' gestation). A survival analysis and adjusted Cox proportional hazards model were used to examine a composite outcome of 40% decline in eGFR or progression to kidney failure. An adjusted logistic regression model was used to examine remission of proteinuria.

Results

There were 2205 term and 235 preterm participants. Apolipoprotein L1 (APOL1 ) risk alleles were more common in those born preterm. More pediatric than adult participants in Cure Glomerulonephropathy were born preterm: 12.8% versus 7.69% (P < 0.001). Adults born preterm compared with term had a higher prevalence of FSGS (35% versus 25%, P = 0.01) and APOL1 high-risk genotype (9.4% versus 4.2%, P = 0.01). Participants born preterm had a shorter time interval to a 40% eGFR decline/kidney failure after biopsy (P = 0.001). In adjusted analysis, preterm participants were 28% more likely to develop 40% eGFR decline/kidney failure (hazard ratio: 1.28 [1.07 to 1.54], P = 0.008) and 38% less likely to attain complete remission of proteinuria (odds ratio: 0.62 [0.45 to 0.87], P = 0.006). There was no significant difference in cardiovascular events.

Conclusions

Preterm birth was a risk factor for adverse outcomes in this heterogeneous cohort of children and adults with glomerular disease. Adults born preterm were more likely to have an APOL1 high-risk genotype and FSGS. In analyses adjusted for FSGS and APOL1 risk status, there was less remission and faster progression of kidney disease in those born preterm.

Acute Kidney Injury in Neonatal Intensive Care Unit: Epidemiology, Diagnosis and Risk Factors

Acute kidney injury (AKI) is associated with long-term consequences and poor outcomes in the neonatal intensive care unit. Its precocious diagnosis represents one of the hardest challenges in clinical practice due to the lack of sensitive and specific biomarkers. Currently, neonatal AKI is defined with urinary markers and serum creatinine (sCr), with limitations in early detection and individual treatment. Biomarkers and risk factor scores were studied to predict neonatal AKI, to early identify the stage of injury and not the damage and to anticipate late increases in sCr levels, which occurred when the renal function already began to decline. Sepsis is the leading cause of AKI, and sepsis-related AKI is one of the main causes of high mortality. Moreover, preterm neonates, as well as patients with post-neonatal asphyxia or after cardiac surgery, are at a high risk for AKI. Critical patients are frequently exposed to nephrotoxic medications, representing a potentially preventable cause of AKI. This review highlights the definition of neonatal AKI, its diagnosis and new biomarkers available in clinical practice and in the near future. We analyze the risk factors involving patients with AKI, their outcomes and the risk for the transition from acute damage to chronic kidney disease.

Podocyte involvement in the pathogenesis of preterm-related long-term chronic kidney disease

With the continuous advancement of neonatal intensive care technology, the survival rate of preterm infants is gradually increasing. However, this improvement in survival is accompanied by long-term prognostic implications in various systems. In the field of renal diseases, current epidemiological data indicate that preterm birth is a significant risk factor for the development of long-term chronic kidney disease (CKD). This not only imposes an economic burden on patients families but also severely impacts their quality of life. Understanding the underlying mechanisms involved in this process could offer potential strategies for early prevention and management of CKD. Although the nephron number hypothesis is currently widely accepted as a mechanism, there has been limited exploration regarding podocytes - one of the most important structures within nephrons - in relation to long-term CKD associated with preterm birth. Therefore, this review aims to summarize current knowledge on how prematurity influences CKD development overall, while specifically focusing on our current understanding of podocytes in relation to prematurity.

Pediatric kidney dimensions and risk of persistent albuminuria in Mexican adolescents

In Mexico, chronic kidney disease of unknown origin is highly prevalent. Screening studies in adolescents have shown persistent microalbuminuria (pACR), adaptive podocytopathy and decreased kidney volume (KV). Here, we sought to develop normality tables of kidney dimensions by ultrasound in the Mexican state of Aguascalientes pediatric population (0 to 18y) and evaluate the relationship between the KV and pACR among the region's adolescents in a cross-sectional study. Kidney length (KL) and KV were determined by ultrasound. Our findings were compared with those in international literature of different populations where tables and graphs of normal kidney dimensions by ultrasound were reported. We compared organ dimensions in individuals above the age of 11 without albuminuria with those in patients with pACR recruited through screening studies in adolescents in Aguascalientes. This included 1068 individuals to construct percentile tables and graphs of the KL. Kidney dimensions were significantly lower when compared with all international comparisons. From a total 14,805 screen individuals, we compared 218 adolescents with pACR and 377 individuals without significant albuminuria. The Total KV adjusted to body surface (TKVBS) was significantly associated with pACR (odds ratio 1.03, 95% confidence interval 1.02-1.03). The upper quartile of TKVBS was highly associated with pACR (7.57, 4.13-13.87), hypertension (2.53, 1.66-3.86), and hyperfiltration (26 vs 11.5%). Thus, TKVBS is directly associated with pACR while greater KV, arterial hypertension, and hyperfiltration in patients with pACR suggest that the increase in volume is secondary to kidney hypertrophy. Additionally, the adaptative podocytopathy with low fibrosis seen on kidney biopsy which was performed in a subset of patients, and the smaller kidney dimensions in our population point to prenatal oligonephronia as the primary cause of the detected kidney disease.

Deletion of NuRD component Mta2 in nephron progenitor cells causes developmentally programmed FSGS

Low nephron endowment at birth is a risk factor for chronic kidney disease. The prevalence of this condition is increasing due to higher survival rates of preterm infants and children with multi- organ birth defect syndromes that affect the kidney and urinary tract. We created a mouse model of congenital low nephron number due to deletion of Mta2 in nephron progenitor cells. Mta2 is a core component of the Nucleosome Remodeling and Deacetylase (NuRD) chromatin remodeling complex. These mice developed albuminuria at 4 weeks of age followed by focal segmental glomerulosclerosis (FSGS) at 8 weeks, with progressive kidney injury and fibrosis. Our studies reveal that altered mitochondrial metabolism in the post-natal period leads to accumulation of neutral lipids in glomeruli at 4 weeks of age followed by reduced mitochondrial oxygen consumption. We found that NuRD cooperated with Zbtb7a/7b to regulate a large number of metabolic genes required for fatty acid oxidation and oxidative phosphorylation. Analysis of human kidney tissue also supported a role for reduced mitochondrial lipid metabolism and ZBTB7A/7B in FSGS and CKD. We propose that an inability to meet the physiological and metabolic demands of post-natal somatic growth of the kidney promotes the transition to CKD in the setting of glomerular hypertrophy due to low nephron endowment.

From Diabetic Nephropathy to End-Stage Renal Disease: The Effect of Chemokines on the Immune System

Background

Diabetic nephropathy (DN) is a major cause of end-stage renal disease (ESRD), and there is growing evidence to support the role of immunity in the progression of DN to ESRD. Chemokines and chemokine receptors (CCRs) can recruit immune cells to sites of inflammation or injury. Currently, no studies have reported the effect of CCRs on the immune environment during the progression of DN to ESRD.

Methods

Differentially expressed genes (DEGs) from the GEO database were identified in DN patients versus ESRD patients. GO and KEGG enrichment analyses were performed using DEGs. A protein-protein interaction (PPI) network was constructed to identify hub CCRs. Differentially expressed immune cells were screened by immune infiltration analysis, and the correlation between immune cells and hub CCRs was also calculated.

Result

In this study, a total of 181 DEGs were identified. Enrichment analysis showed that chemokines, cytokines, and inflammation-related pathways were significantly enriched. Combining the PPI network and CCRs, four hub CCRs (CXCL2, CXCL8, CXCL10, and CCL20) were identified. These hub CCRs showed an upregulation trend in DN patients and a downregulation trend in ESRD patients. Immune infiltration analysis identified a variety of immune cells that underwent significant changes during disease progression. Among them, CD56bright natural killer cell, effector memory CD8 T cell, memory B cell, monocyte, regulatory T cell, and T follicular helper cell were significantly associated with all hub CCR correlation.

Conclusion

The effect of CCRs on the immune environment may contribute to the progression of DN to ESRD.