BackgroundNephropathic cystinosis is an inherited autosomal recessive lysosomal storage disorder characterized by the pathological accumulation and crystallization of cystine inside different cell types. WBC cystine determination forms the basis for the diagnosis and therapeutic monitoring with the cystine depleting drug (cysteamine). The chitotriosidase enzyme is a human chitinase, produced by activated macrophages. Its elevation is documented in several lysosomal storage disorders. Although, about 6% of Caucasians have enzyme deficiency due to homozygosity of 24-bp duplication mutation in the chitotriosidase gene, it is currently established as a screening marker and therapeutic monitor for Gaucher’s disease.MethodsPlasma chitotriosidase activity was measured in 45 cystinotic patients, and compared with 87 healthy controls and 54 renal disease patients with different degrees of renal failure (CKD1-5). Chitotriosidase levels were also correlated with WBC cystine in 32 treated patients. Furthermore, we incubated control human macrophages in-vitro with different concentrations of cystine crystals and monitored the response of tumor necrosis factor-alpha (TNF-α) and chitotriosidase activity. We also compared plasma chitotriosidase activity in cystinotic knocked-out (n = 10) versus wild-type mice (n = 10).ResultsPlasma chitotriosidase activity in cystinotic patients (0–3880, median 163 nmol/ml/h) was significantly elevated compared to healthy controls (0–90, median 18 nmol/ml/h) and to CKD patients (0–321, median 52 nmol/ml/h), P < 0.001 for both groups. Controls with decreased renal function had mild to moderate chitotriosidase elevations; however, their levels were significantly lower than in cystinotic patients with comparable degree of renal insufficiency. Chitotriosidase activity positively correlated with WBC cystine content for patients on cysteamine therapy (r = 0.8), P < 0.001. In culture, human control macrophages engulfed cystine crystals and released TNF-α into culture supernatant in a crystal concentration dependent manner. Chitotriosidase activity was also significantly increased in macrophage supernatant and cell-lysate. Furthermore, chitotriosidase activity was significantly higher in cystinotic knocked-out than in the wild-type mice, P = 0.003.ConclusionsThis study indicates that cystine crystals are potent activators of human macrophages and that chitotriosidase activity is a useful marker for this activation and a promising clinical biomarker and therapeutic monitor for nephropathic cystinosis.

sFLT-1 may contribute to pathogenesis of albuminuria in SCD patients and constitute a novel renal biomarker of SN.

Acute kidney injury (AKI) is a complex disorder with clinical manifestations ranging from mild dysfunction to complete kidney failure. The published literature on the incidence and outcome of AKI in the critically ill neonatal population is scarce. The aim of this study was to evaluate the types, the associated risk factors and short-term outcome of AKI in the critically ill neonates. A cohort study was conducted including 100 critically ill neonates successively admitted to the Neonatal Intensive Care Unit. The inclusion criteria were a gestational age ≥28 weeks and body weight ≥1 kg. Exclusion criteria included those with multiple congenital anomalies or on drugs altering glomerular filtration rate or AKI developing postoperatively. Neonates were evaluated for the development of AKI [creatinine >1.5 mg/dL and/or blood urea nitrogen (BUN) >20 mg/dL] and were assigned as group A (who developed AKI) and group B (who did not develop AKI). Forty-one patients developed AKI (group A) among whom nine (22%) showed oliguric AKI. The most common risk factors among group A patients were sepsis (75.6%) and nephrotoxic drug administration (75.6%), followed by shock (39%). There were no statistically significant differences between both groups except for male sex predominance and necrotizing enterocolitis (NEC), which were significantly higher among group A (P <0.05). Use of continuous positive airway pressure (CPAP) ventilation was significantly higher in neonates without AKI (13.6% vs 0.0%, P = 0.02). The mortality rate among group A reached 51.2%. Various risk factors including gender, gestational age, birth weight, shock, NEC, sepsis, nephrotoxic drugs, oliguria and mechanical ventilation were studied as regards outcome of group A, and all factors except gender and oliguria proved to be significantly higher in deceased neonates. Male sex and NEC were important risk factors for developing AKI that was predominantly non-oliguric. CPAP ventilation may have a protective effect against AKI. The mortality rate was more than three times higher in the AKI group.

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