Magnetic resonance imaging based kidney volume assessment for risk stratification in pediatric autosomal dominant polycystic kidney disease

Introduction

In the pediatric context, most children with autosomal dominant polycystic kidney disease (ADPKD) maintain a normal glomerular filtration rate (GFR) despite underlying structural kidney damage, highlighting the critical need for early intervention and predictive markers. Due to the inverse relationship between kidney volume and kidney function, risk assessments have been presented on the basis of kidney volume. The aim of this study was to use magnetic resonance imaging (MRI)-based kidney volume assessment for risk stratification in pediatric ADPKD and to investigate clinical and genetic differences among risk groups.

Methods

This multicenter, cross-sectional, and case-control study included 75 genetically confirmed pediatric ADPKD patients (5-18 years) and 27 controls. Kidney function was assessed by eGFR calculated from serum creatinine and cystatin C using the CKiD-U25 equation. Blood pressure was assessed by both office and 24-hour ambulatory measurements. Kidney volume was calculated from MRI using the stereological method. Total kidney volume was adjusted for the height (htTKV). Patients were stratified from A to E classes according to the Leuven Imaging Classification (LIC) using MRI-derived htTKV.

Results

Median (Q1-Q3) age of the patients was 6.0 (2.0-10.0) years, 56% were male. There were no differences in sex, age, height-SDS, or GFR between the patient and control groups. Of the patients, 89% had PKD1 and 11% had PKD2 mutations. Non-missense mutations were 73% in PKD1 and 75% in PKD2. Twenty patients (27%) had hypertension based on ABPM. Median htTKV of the patients was significantly higher than controls (141 vs. 117 ml/m, p = 0.0003). LIC stratification revealed Classes A (38.7%), B (28%), C (24%), and D + E (9.3%). All children in class D + E and 94% in class C had PKD1 variants. Class D + E patients had significantly higher blood pressure values and hypertension compared to other classes (p > 0.05 for all).

Discussion

This study distinguishes itself by using MRI-based measurements of kidney volume to stratify pediatric ADPKD patients into specific risk groups. It is important to note that PKD1 mutation and elevated blood pressure were higher in the high-risk groups stratified by age and kidney volume. Our results need to be confirmed in further studies.

Urine soluble TLR4 levels may contribute to predict urinary tract infection in children: the UTILISE Study

BACKGROUND

One of the most common bacterial infections in childhood is urinary tract infection (UTI). Toll-like receptors (TLRs) contribute to immune response against UTI recognizing specific pathogenic agents. Our aim was to determine whether soluble TLR4 (sTLR4), soluble TLR5 (sTLR5) and interleukin 8 (IL-8) can be used as biomarkers to diagnose UTI. We also aimed to reveal the relationship between urine Heat Shock Protein 70 (uHSP70) and those biomarkers investigated in this study.

METHODS

A total of 802 children from 37 centers participated in the study. The participants (n = 282) who did not meet the inclusion criteria were excluded from the study. The remaining 520 children, including 191 patients with UTI, 178 patients with non-UTI infections, 50 children with contaminated urine samples, 26 participants with asymptomatic bacteriuria and 75 healthy controls were included in the study. Urine and serum levels of sTLR4, sTLR5 and IL-8 were measured at presentation in all patients and after antibiotic treatment in patients with UTI.

RESULTS

Urine sTLR4 was higher in the UTI group than in the other groups. UTI may be predicted using 1.28 ng/mL as cut-off for urine sTLR4 with 68% sensitivity and 65% specificity (AUC = 0.682). In the UTI group, urine sTLR4 levels were significantly higher in pyelonephritis than in cystitis (p < 0.0001). Post-treatment urine sTLR4 levels in the UTI group were significantly lower than pre-treatment values (p < 0.0001).

CONCLUSIONS

Urine sTLR4 may be used as a useful biomarker in predicting UTI and subsequent pyelonephritis in children with UTI. A higher resolution version of the Graphical abstract is available as Supplementary information.

Spatial Distribution of Macrophage Subtypes Among Rejection Subtypes in Renal Transplant Biopsies by Dual Immunohistochemistry

We performed dual immunohistochemistry for CD163/CD34 and CD68/CD34 in 108 renal transplant indication biopsies to investigate the presence and distribution of macrophages in various renal compartments. All Banff scores and diagnoses were revised according to the Banff 2019 classification. CD163 and CD68 positive cell counts (CD163pos and CD68pos) were evaluated in the interstitium, glomerular mesangium, and, within glomerular and peritubular capillaries. The diagnosis was antibody-mediated rejection (ABMR) in 38 (35.2%), T-cell mediated rejection (TCMR) in 24 (22.2%), mixed rejection in 30 (27.8%), and no rejection in 16 (14.8%). Banff lesion scores t , i , and ti were correlated with both CD163 and CD68 interstitial inflammation scores ( r > 0.30; P < 0.05). Glomerular total CD163pos was correlated to Banff lesion scores g and cg ( r > 0.30; P < 0.05). Glomerular total, mesangial, and intracapillary CD68pos were correlated with g ( r > 0.30; P < 0.05). Both glomerular total and peritubular capillary CD68pos were correlated with peritubular capillaritis ( r > 0.30; P < 0.05). Glomerular CD163pos were significantly higher in ABMR compared with no rejection, in mixed rejection compared with no rejection and TCMR. CD163pos in peritubular capillaries was significantly higher in mixed rejection compared with no rejection. Glomerular CD68pos was significantly higher in ABMR compared with no rejection. CD68pos per peritubular capillary was higher in mixed rejection, ABMR, and TCMR compared with no rejection. In conclusion, compared with CD68 positive macrophages, localization of CD163 positive macrophages in various renal compartments seems to be different among rejection subtypes and their glomerular infiltration seems to be more specific for the presence of ABMR component.

Humoral and cellular immune response to SARS-CoV-2 mRNA BNT162b2 vaccine in pediatric kidney transplant recipients compared with dialysis patients and healthy children

BACKGROUND

Compared with the general population, the immune response to COVID-19 mRNA vaccines is lower in adult kidney transplant recipients (KTRs). However, data is limited for pediatric KTRs. In this study, we aimed to assess humoral and cellular immune responses to the COVID-19 mRNA vaccine in pediatric KTRs.

METHODS

This multicenter, prospective, case-control study included 63 KTRs (37 male, aged 12-21 years), 19 dialysis patients, and 19 controls. Humoral (anti-SARS-CoV2 IgG, neutralizing Ab (nAb)) and cellular (interferon-gamma release assay (IGRA)) immune responses were assessed at least one month after two doses of BNT162b2 mRNA vaccine.

RESULTS

Among COVID-19 naïve KTRs (n = 46), 76.1% tested positive for anti-SARS-CoV-2 IgG, 54.3% for nAb, and 63% for IGRA. Serum levels of anti-SARS-CoV-2 IgG and nAb activity were significantly lower in KTRs compared to dialysis and control groups (p < 0.05 for all). Seropositivity in KTRs was independently associated with shorter transplant duration (p = 0.005), and higher eGFR (p = 0.007). IGRA titer was significantly lower than dialysis patients (p = 0.009). Twenty (43.4%) KTRs were positive for all immune parameters. Only four of 11 seronegative KTRs were IGRA-positive. COVID-19 recovered KTRs had significantly higher anti-SARS-CoV-2 IgG and nAb activity levels than COVID-19 naïve KTRs (p = 0.018 and p = 0.007, respectively).

CONCLUSIONS

The humoral and cellular immune responses to SARS-CoV-2 mRNA BNT162b2 vaccine are lower in pediatric KTRs compared to dialysis patients. Further prospective studies are required to demonstrate the clinical efficacy of the mRNA vaccine in KTRs. This prospective study was registered in ClinicalTrials.gov (NCT05465863, registered retrospectively at 20.07.2022). A higher resolution version of the Graphical abstract is available as Supplementary information.

PROGRESS STUDY: Progression of chronic kidney disease in children and heat shock proteins

Various molecular and cellular processes are involved in renal fibrosis, such as oxidative stress, inflammation, endothelial cell injury, and apoptosis. Heat shock proteins (HSPs) are implicated in the progression of chronic kidney disease (CKD). Our aim was to evaluate changes in urine and serum HSP levels over time and their relationships with the clinical parameters of CKD in children. In total, 117 children with CKD and 56 healthy children were examined. The CKD group was followed up prospectively for 24 months. Serum and urine HSP27, HSP40, HSP47, HSP60, HSP70, HSP72, and HSP90 levels and serum anti-HSP60 and anti-HSP70 levels were measured by ELISA at baseline, 12 months, and 24 months. The urine levels of all HSPs and the serum levels of HSP40, HSP47, HSP60, HSP70, anti-HSP60, and anti-HSP70 were higher at baseline in the CKD group than in the control group. Over the months, serum HSP47 and HSP60 levels steadily decreased, whereas HSP90 and anti-HSP60 levels steadily increased. Urine HSP levels were elevated in children with CKD; however, with the exception of HSP90, they decreased over time. In conclusion, our study demonstrates that CKD progression is a complicated process that involves HSPs, but they do not predict CKD progression. The protective role of HSPs against CKD may weaken over time, and HSP90 may have a detrimental effect on the disease course.

MO001THE EUROPEAN DRTA REGISTRY: AN INITIAL DATA ANALYSIS*

Background and Aims

Distal renal tubular acidosis (dRTA) is a rare disorder characterised by an inability of the distal tubule to secrete acid, leading to metabolic acidosis. Clinical consequences typically include hypokalaemia, hypercalciuria with nephrocalcinosis and/or urolithiasis, as well as bone disease. Treatment with adequate alkali supplementation corrects the acidosis and hypercalciuria, but there are few data on long-term outcome. In 2018, a registry for dRTA was established by the European Society for Paediatric Nephrology, hosted by the European Rare Kidney Disease Reference Network. Here, we present an initial analysis of data in the registry.

Method

Analysis of data entered into the registry by the cut-off data of 18/11/2020.

Results

A total of 135 patients had been entered, of which 106 had additional data from an annual follow-up visit. Median age at last visit was 10 years (range 0-54), including 16 adults (&gt;17y). Genetic testing had been performed in 91 subjects and causative variants were reported in 74 (81%). Pertinent clinical details according to genetic group are listed in table 1.

Treatment was provided with at least 15 different preparations, containing citrate or bicarbonate, given in 1-10 (median 3) daily doses.

Adequate treatment at last follow-up, as judged by a plasma bicarbonate level &gt;21 mmol/l and a urine calcium-creatinine ratio in the age-specific normal range was present in 46% of subjects.

There was a trend for higher eGFR and height SDS in subjects with adequate treatment compared to those without, but this was not statistically significant.

Conclusion

Currently available data demonstrate the difficulties in treating dRTA, with less than half of subjects achieving adequate control of their acidosis. By collecting long-term data, the registry will provide important information on the prognosis and complications of dRTA and to what degree these can be prevented with treatment. Enrollment of further, especially adult patients will contribute to our understanding of this rare disorder.

Association of BK Virus Titers With Lymphocyte Count in Renal Transplant Patients

OBJECTIVES

Regular screening for the BK virus (BKV) is recommended for early intervention in renal transplant patients. Identification of predictors for the development of BK viremia would improve their monitoring. We performed a retrospective study investigating whether the lymphocyte count may be a predictor of BKV development in renal transplant patients.

PATIENTS AND METHODS

We retrospectively analyzed 268 renal transplant patients who were followed in our clinic from January 2011 to August 2014. The viral loads of BKV in blood detected by quantitative real-time polymerase chain reaction test were performed according to relevant guidelines. We also retrospectively monitored lymphocyte count, creatinine, immunosuppressive drug doses, and tacrolimus/cyclosporine/mTor inhibitors levels during the same time as BKV screening. Demographic and other clinical data were extracted from patients' files. The calculation of correlation coefficients and receiver operating characteristics (ROC) curve analysis were performed.

RESULTS

Overall, 16 patients (5.9%) who experienced BKV-DNA positivity were included the study. Mean age of patients was 38.2 ± 12.8 years. All patients received steroid and calcineurin inhibitors (CNIs). Mycophenolate mofetil/mycophenolic acid (MMF/MPA) was administered to 14 patients. BKV-DNA was found in 64 of the 88 (72.7%) plasma samples. The lymphocyte count on the first day of positive BKV-DNA test was significantly lower than in those with negative BKV-DNA results (1700/μl vs 2400/μl, respectively; P = .009). Its AUC of the ROC curve was 0.77 (P = .012). The optimal cutoff point for lymphocyte count was 1900/μl, and sensitivity and specificity for predict BKV positivity were 75% and 78.57%, respectively. We also found that lymphocyte count negatively correlated with the first detectable BKV titers (r = -0.438; P = .015). However, there is no relation between CNI/mTOR inhibitor levels, MMF/MPA doses, lymphocyte count, and all BKV-titers.

CONCLUSIONS

Decreased lymphocyte count may be a predictor for preceding BKV viremia. Clinicians should be more careful in terms of the decreased lymphocyte count in case of BKV replication in renal transplant patients.

Effects of methylene blue in acute lung injury induced by blunt chest trauma

BACKGROUND

We studied whether methylene blue (MB) treatment blunts chest trauma-induced lung injury in rats.

MATERIAL AND METHODS

Forty male Sprague-Dawley rats, 200-300g, were used. The rats were divided into five groups (n=8): control, early contusion (EC), early contusion + methylene blue (2 mg/kg, EC+MB), late contusion (LC), and late contusion + methylene blue (2 mg/kg, LC+MB).

RESULTS

Histopathological analysis showed increased hemorrhage, alveolar wall thickness, edema, and inflammatory cell infiltrates in the EC and LC rats, which decreased upon MB treatment. Immunohistochemical studies revealed that MB reduced activation of inducible nitric oxide synthase (iNOS) and the number of active terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells. A significant increase was observed in the malondialdehyde (MDA) and nitric oxide (NO) levels in the EC group compared to the control group (p<0.05). In addition, a significant decrease was reported in the glutathione (GSH), superoxide dismutase (SOD), and glutathione peroxidase (GPx) levels (p<0.01), but no significant difference was observed in the catalase (CAT) levels among the groups. The MDA level was significantly higher in the LC group compared to the control group, whereas the GSH level was significantly lower compared to the control group. The NO level in the EC+MB group was significantly lower when compared to the NO level in the EC group (p<0.05).

CONCLUSION

The present study provides evidence that MB might serve as a therapeutic treatment for blunt chest trauma.

Bilateral spigelian hernia concomitant with multiple skeletal anomalies and fibular aplasia in a child

A child with Spigelian hernia, concomitant multiple skeletal anomalies and whole body hemihypoplasia and fibular aplasia is presented here. Irrespective of the patient's age at presentation, Spigelian hernias associated with anomalies are congenital in origin. This case emphasizes the fact that a bilateral Spigelian hernia can occur in children together with multiple skeletal anomalies.