Urinary podocalyxin as a possible novel marker of intrauterine nephrogenesis and extrauterine podocyte injury

Investigation of clinical and subclinical renal damage in Psoriasis

Psoriasis is a common systemic inflammatory disease and the literature has reported varying results regarding the renal involvement of psoriasis. Although many studies have investigated the presence of chronic renal damage in patients with psoriasis, there are few studies demonstrating subclinical renal damage. The aim of this study was to prospectively evaluate the presence of clinical and subclinical renal damage in patients with psoriasis vulgaris (PV). The study prospectively enrolled 44 PV patients and 44 healthy controls. Serum urea (BUN), creatinine levels, glomerular filtration rate (GFR), complete urinalysis, urine microscopy and subclinical renal damage markers albuminuria, proteinuria, urinary kidney injury molecule-1 (uKIM-1)/creatinine, urinary neutrophil gelatinase-associated lipocalin (uNGAL)/creatinine and urinary podocalyxin/creatinine levels were measured and compared in both groups.Proteinuria levels were found to be statistically significantly higher in patients with PV (p = 0.021). A positive correlation was observed between proteinuria levels and uKIM-1/creatinine, uNGAL/creatinine and albuminuria levels in the patient group (p = 0.013, r = 0.373; p = 0.017, r = 0.358; p = 0.017, r = 0.358, respectively). This study concluded that PV does not cause clinical kidney injury. Increased proteinuria in PV patients supports the presence of subclinical renal damage. Regular monitoring of proteinuria and uKIM-1/creatinine, uNGAL/creatinine and albuminuria levels, which are positively correlated with proteinuria, may allow early detection of renal damage in PV patients.

Urine podocyte mRNA loss in preterm infants and related perinatal risk factors

BACKGROUND

Preterm birth has been identified as a risk factor for development of long-term chronic kidney disease. Podocyte loss has been reported to contribute to this process in preterm animal models. However, details about podocyte loss in preterm infants and related perinatal risk factors have not been well clarified.

METHODS

Forty full-term infants and 106 preterm infants were enrolled. Urine samples were collected from full-term infants within 4-7 days of birth and preterm infants at 37-40 weeks of corrected age. Levels of urine podocin mRNA, urine protein (UP), and urine microalbumin (UMA) were measured, and the relationship between these markers was evaluated. Clinical information in these infants was collected, and potential correlates that may lead to increased podocyte loss during the perinatal period were identified using linear regression analysis.

RESULTS

Urine podocyte loss indicated by the urine podocin mRNA to creatinine ratio (UpodCR) was higher in preterm infants than in full-term infants. UpodCR was correlated with the levels of UP and UMA. Multiple linear regression analysis also showed that lower gestational age (GA) at birth and small for gestational age (SGA) were high risk factors for urine podocyte loss.

CONCLUSIONS

Increasing urine podocyte loss was identified in preterm infants. Moreover, perinatal factors were associated with podocyte loss and may be a potential direction for comprehensive research and intervention in this field. A higher resolution version of the Graphical abstract is available as Supplementary information.

Effect of fetal growth restriction on urinary podocalyxin levels at birth in preterm neonates

BACKGROUND

Small-for-gestational-age (SGA) neonates are at a higher risk of adult-onset metabolic disorders because of fetal programming in the presence of growth restriction. Nephrogenesis may also be affected in fetal growth restriction. This study hypothesized that urinary podocalyxin levels, a marker of nephrogenesis, would be lower among preterm SGA neonates as compared to appropriate-for-gestational-age (AGA) controls.

METHODS

This cross-sectional study enrolled gestation-matched SGA (n = 90) and AGA (n = 45) neonates born at 26⁰-36⁶ weeks of gestation. The SGA group comprised of 45 neonates with birth weight between 3^rd and 10^th centile and 45 neonates with birth weight <3^rd centile. The primary outcome of the study was the difference in urinary podocalyxin levels between SGA and AGA neonates. Glomerular and tubular functions were also assessed.

RESULTS

Urinary podocalyxin levels were similar in SGA and AGA neonates (ng/mg of creatinine; median [interquartile range]: 28.7 [4.8-70.2] vs. 18.7 [3.1-55.9]), P value 0.14). No correlation was observed between birth weight centile and urinary podocalyxin levels (r: -0.06). Glomerular filtration rate, fractional excretion of sodium, and serum β-2-microglobulin levels were comparable across the study groups.

CONCLUSIONS

Glomerular development as assessed by urinary podocalyxin levels and renal functions are comparable in SGA and AGA preterm neonates.

IMPACT

Neonates born with fetal growth restriction are at a higher risk of adult-onset metabolic disorders because of fetal programming. This cross-sectional study investigated the effect of presence and severity of fetal growth restriction on glomerular development by measuring urinary podocalyxin levels in preterm infants. This study did not observe any effect of the presence or severity of fetal growth restriction on urinary podocalyxin levels and other markers of glomerular and renal tubular functions.

Intracellular complement activation in podocytes aggravates immune kidney injury in trichloroethylene-sensitized mice

Trichloroethylene (TCE) as a common organic solvent in industrial production can cause occupational medicamentosa-like dermatitis (OMDT) in some exposed workers. In addition to systemic skin damage, OMDT is also accompanied by severe kidney injury. Our previous studies show that complement (C) plays an important role in immune kidney injury caused by TCE. Specifically, C3 is mainly deposited on glomeruli. Recent studies have found that intracellular complement can be activated by cathepsin L (CTSL) and exert a series of biological effects. The purpose of this study was to explore where C3 on glomeruli comes from and what role it plays. A BALB/c mouse model of skin sensitization induced by TCE in the presence or absence of CTSL inhibitor (CTSLi,10 mg/kg). In TCE sensitization-positive mice, C3 was mainly expressed on podocytes and the expression of CTSL significantly increased in podocytes. Kidney function test and related indicators showed abnormal glomerular filtration and transmission electron microscopy revealed ultrastructure damage to podocytes. These lesions were alleviated in TCE/CTSLi positive mice. These results provide the first evidence that in TCE-induced immune kidney injury, intracellular complement in podocytes can be over-activated by CTSL and aggravates podocytes injury, thereby damaging glomerular filtration function. Intracellular complement activation and cathepsin L in podocytes may be a potential target for treating immune kidney injury induced by TCE.