Defective cell-mediated immunity in lipoid nephrosis

[Pathogenesis and treatment of idiopathic nephrotic syndrome in adults]

Idiopathic nephrotic syndrome is the most frequent glomerular disease in children and in young adults. While genetic analyses have provided new insights into disease pathogenesis through the discovery of several podocyte genes mutated in distinct forms of inherited nephrotic syndrome, the molecular bases of minimal change nephrotic syndrome and focal and segmental glomerulosclerosis with relapses remain unclear. Although immune cell disorders, which may involve both innate and adaptive immunity, appear to play a role in the pathogenesis of steroid sensitive minimal change nephrotic syndrome, the mechanisms by which they induce podocyte dysfunction remain unresolved. It was postulated that podocyte injury results from a circulating factor secreted by abnormal T cells, but the possibility that bipolarity of the disease results from a functional disorder shared by both immune cells and the podocytes is not excluded. Minimal change nephrotic syndrome relapses are associated with an expansion of T and B cell compartments and production of growth factors as well as many cytokines. Dysfunction of T cells is supported by several findings including, inhibition of a type IV hypersensitivity reaction and unclassical T helper polarization, resulting from transcriptional interference between Th1 and Th2 transcriptional factors. A low serum level of some IgG fractions is frequently observed suggesting a defect in T-B cell cooperation, which remains to be explored. In this review, we discuss recent advances in the pathogenesis and the therapy of idiopathic nephrotic syndrome.

[Minimal change nephrotic syndrome : new insights into disease pathogenesis]

Idiopathic nephrotic syndrome is the most frequent glomerular disease in children. While genetic analyses have provided new insights into disease pathogenesis through the discovery of several podocyte genes mutated in distinct forms of inherited nephrotic syndrome, the molecular bases of minimal change nephrotic syndrome (MCNS) and focal and segmental glomerulosclerosis (FSGS) with relapse remain unclear. Although immune cell disorders, which may involve both innate and adaptive immunity, appear to play a role in the pathogenesis of steroid sensitive MCNS, the mechanisms by which they induce podocyte dysfunction remain unresolved. It was postulated that podocyte injury results from a circulating factor secreted by abnormal T cells, but the possibility that bipolarity of the disease results from a functional disorder shared by both cell systems is not excluded. MCNS relapses are associated with an activation of the immune system, including an expansion of T and B cell compartments and production of growth factors as well as many cytokines. Dysfunction of T cells is supported by three main findings: (1) inhibition of a type III hypersensitivity reaction ; (2) defects in immunoglobulin switch ; (3) unclassical T helper polarization resulting from transcriptional interference between Th1 and Th2 transcriptional factors.

Indirect quantification of lipid peroxidation in steroid responsive nephrotic syndrome

AIMS

To test the hypothesis that oxygen free radicals are mediators of excessive protein permeability in steroid responsive nephrotic syndrome.

DESIGN

Case control study.

PATIENTS

20 children with steroid responsive nephrotic syndrome; controls: 20 children admitted for elective surgery.

SETTING

The paediatric and biochemistry departments of the Maulana Azad Medical College, New Delhi, India.

METHODS

Blood samples were taken twice from children with nephrotic syndrome (on admission and on urinary remission) and once from controls. Biochemical assays were carried out on these blood samples to quantify the indirect markers of free radical injury in the body, namely: vitamin E, reduced glutathione (GSH), glucose-6-phosphate dehydrogenase (G6PD), malonyldialdehyde (MDA), and membrane cholesterol in erythrocytes.

RESULTS

There was some evidence supportive of oxidative injury in the children with nephrotic syndrome in the form of greatly reduced concentrations of antioxidants vitamin E (155.4 microg/100 ml in controls, 86.4 microg/100 ml in patients) and G6PD (364 mU/ml in controls, 205.1 mU/ml in patients). However, concentrations of the oxidation byproduct MDA were raised only in the remission phase of the disease (0.984 nmol/ml in controls, 1.158 nmol/ml in cases), whereas those of GSH were unaltered.

CONCLUSIONS

Changes in the concentrations of MDA, G6PD, and vitamin E are consistent with increased amounts of oxidation in steroid responsive nephrotic syndrome. Further research is needed to explain whether these changes are a cause or consequence of the disease.

Decreased release of IL-10 by monocytes from patients with lipoid nephrosis

IL-10, a cross-regulatory cytokine produced by several cell types, including monocytes, is known to stimulate B cell growth and maturation and to inhibit cytokine production. In order to characterize further monocyte function in patients with lipoid nephrosis (LN), the release of IL-10 was measured in supernatants of cultured peripheral blood monocytes (PBM) that were obtained from LN patients and healthy controls. Spontaneous and lipopolysaccharide (LPS)-induced IL-10 release was decreased in patients with LN compared with those in normal controls and lower in LN patients with the nephrotic syndrome (NS) than in those without NS. In contrast, the values in IgA nephropathy (IgAN) patients with or without NS did not differ from normal subjects. There was a negative correlation between IL-10 concentration and the quantity of vascular permeability factor (VPF) released in LN patients. These imply that there is a relative deficit in IL-10 release in active LN, which suggests the possibility that inadequate release of IL-10 may lead to increased VPF activity in active LN patients and the measurements of IL-10 may be of value for monitoring kidney disease. The data provide the first detailed analysis of IL-10 in a group of patients with LN.