5-Lipoxygenase and leukotriene A4 hydrolase expression in primary nephrotic syndrome

Autosomal Recessive Congenital Ichthyosis and Steroid-Resistant Nephrotic Syndrome due to Homozygous Mutation in the ALOX12B gene: A Novel Association with Review of Literature

Nephrotic syndrome (NS) associated with autosomal recessive congenital ichthyosis (ARCI) is a rare association. In this article, we described a 4-year-old boy with steroid-resistant NS (SRNS) who had a history of ichthyotic skin lesions since birth. Renal biopsy revealed focal segmental glomerulosclerosis (tip variant). The skin biopsy was consistent with the findings of ichthyosis. Next-generation sequencing revealed a homozygous pathogenic variant (c.1625_1626del) in the exon 12 of the ALOX12B gene, confirming the diagnosis of ARCI2. The ALOX12B gene belongs to the lipoxygenase family and has a pivotal role in the formation of lipid layers in the epidermis. Leukotrienes have a counter-regulatory effect within the inflamed glomeruli, which influences the vascular tone and glomerular basement membrane permeability, that can be implicated in the pathogenesis of the NS. This child is currently in remission, on tacrolimus and low-dose prednisolone, with emollients and is on regular follow-up. SRNS associated with congenital ichthyosis secondary to a mutation in the ALOX12B gene has never been reported so far. The knowledge regarding this novel association will help the treating physicians in diagnosing this condition early, which will enable proper genetic counseling and prognostication of the disease to the family.

Montelukast as an add-on treatment in steroid dependant nephrotic syndrome, randomised-controlled trial

BACKGROUND

The underlying mechanisms of nephrotic syndrome (NS) are still under debate and the need for more effective and less toxic treatment is challenging. We aimed to evaluate the efficacy of montelukast, a leukotriene receptor antagonist as an add-on therapy, and to explore the leukotriene (LT) biology in steroid-dependent nephrotic syndrome (SDNS).

METHODS

A randomized controlled trial was conducted including 32 patients with SDNS who were randomly assigned to receive standard steroid treatment only [low-dose steroid (LDS) group] or standard steroid therapy plus montelukast (Montelukast group). Urine protein/creatinine ratio, serum albumin, creatinine, cholesterol, and plasma LTs (LTB4/C4/D4/E4) were evaluated in all patients before and after treatment.

RESULTS

After treatment, both groups showed a significant decrease of LTB4 and LTC4/D4/E4. Further, the Montelukast group showed a significant decrease in serum creatinine and a significant increase in diastolic blood pressure and protein/creatinine ratio. It also showed a marked decrease in plasma LTC4/D4/E4 compared to the LDS group, although not statistically significant.

CONCLUSIONS

Our findings highlight the effect of montelukast on renal function, but suggest that the clinical and laboratory efficacy of the addition of montelukast to steroids in maintenance treatment of SDNS is debatable.

Proteinuria increases oxylipid concentrations in VLDL and HDL but not LDL particles in the rat

We previously established that proteinuria alters the apolipoprotein content of lipoproteins. This study was conducted to establish whether proteinuria also alters the concentrations of oxidized lipids within lipoprotein density fractions. To this end, we induced passive Heymann nephritis in Sprague Dawley rats and measured an array of alkaline-stable oxylipids in VLDL, LDL, and HDL particles. Proteinuria increased the total oxylipid amounts in the HDL and VLDL fractions. More importantly, these levels were increased when expressed per unit lipoprotein protein, indicating that the oxidized lipid load per particle was increased. Epoxides and diols increased approximately 2-fold in HDL and approximately 5-fold in VLDL, whereas LDL showed approximately 2-fold decreases. The hydroxyeicosatetraenoic acids and hydroxyoctadecadienoic acids (HODEs) increased >4-fold in HDL and >20-fold in VLDL, whereas LDL showed approximately 2-fold decreases in the HODEs. Therefore, nephrotic syndrome alters the lipoprotein oxylipid composition independently of an increase in total lipoprotein levels. These proteinuria-induced changes may be associated with the cardiovascular risk of lipoprotein oxidation.