In vitro lymphocyte dysfunction in lipoid nephrosis mediated by suppressor cells

Urinary cytokines and steroid responsiveness in idiopathic nephrotic syndrome of childhood

BACKGROUND/AIM

Steroid-resistant nephrotic syndrome (SRNS) has been associated with activation of TGF-beta(1) and progression to chronic kidney disease. Steroid-sensitive nephrotic syndrome (SSNS) has been associated with activation of T-cells and favorable outcome. Our objective was to distinguish SRNS from SSNS and focal segmental glomerulosclerosis (FSGS) from minimal change disease (MCD) on the basis of urinary cytokine profile.

METHOD

We used a high-throughput cytokine array. ICAM-1 and TGF-beta(1) in urine and kidney tissue were evaluated by ELISA and immunohistochemistry (IHC), respectively.

RESULTS

Age, gender, race, body mass index, and glomerular filtration rate were similar among groups. There were no statistically significant differences between SRNS (n = 12) and SSNS (n = 12) in regard to the presence of hypertension, treatment with ACE inhibitors, and renal histology. Arrays detected a 1- to 5.5-fold increase in urinary cytokine expression in subjects with idiopathic nephrotic syndrome (INS) as compared to controls. Using ELISA, urinary excretion of ICAM-1 was significantly higher in INS subjects than in controls (control group, n = 12; p = 0.005), but it did not differentiate SRNS from SSNS, or FSGS from MCD. IHC failed to reveal differences in renal tissue expression of ICAM-1 among controls, SRNS and SSNS. There were no significant differences among controls, and patients with SRNS and SSNS in the urinary excretion of TGF-beta(1) (p = 0.21). However, urinary TGF-beta(1) levels were significantly higher in FSGS than in MCD (p = 0.03), and IHC showed increased immunoreactivity in FSGS.

CONCLUSION

Our data indicate that urinary TGF-beta(1) was able to differentiate between FSGS and MCD but was not a biomarker of steroid responsiveness.

Nephrotic syndrome associated with chronic lymphocytic leukaemia

The simultaneous presentation of B-cell chronic lymphocytic leukaemia and nephrotic syndrome is described. The leukaemia responded to cytotoxic therapy but prednisolone was required to achieve remission of the nephrotic syndrome. The nephrotic syndrome relapsed when the leukaemia again became active and the white cell count rose above 20x10(9)/l, and it remitted again with treatment. The relationship between the two diseases is discussed.

Th1 and Th2 cytokine mRNA profiles in childhood nephrotic syndrome: evidence for increased IL-13 mRNA expression in relapse

Idiopathic nephrotic syndrome of childhood is thought to be associated with T lymphocyte dysfunction often triggered by viral infections, with the production of circulating factor(s) resulting in proteinuria. In view of the conflicting evidence of T cell activation and Th1 or Th2 pattern of cytokine synthesis in this disease, this study examined the mRNA expression of interleukin-2 (IL-2), interferon-gamma, IL-4, and IL-13 from CD4+ and CD8+ T cells in steroid-responsive nephrotic patients in relapse and remission. Fifty-five children with steroid-responsive nephrotic syndrome were included in this study, together with 34 normal controls and 24 patient controls with viral infections. RNA was isolated from purified CD4+ or CD8+ cells from peripheral blood and subjected to reverse transcription-PCR. Cytokine mRNA expression was measured semiquantitatively, and a cytokine index was derived from densitometric readings, with cyclophilin as the housekeeping gene. Both cross-sectional and paired data showed an increased CD4+ and CD8+ IL-13 mRNA expression in patients with nephrotic relapse as compared to remission, normal, and patient controls (P < 0.008). This was also associated with increased cytoplasmic IL-13 expression in phorbol myristate acetate/ionomycin-activated CD3+ cells (6.66+/-3.39%) from patients with nephrotic relapse compared to remission (2.59+/-1.35%) (P < 0.0001). However, there was no significant difference in CD4+ or CD8+ IL-2, interferon-gamma and IL-4 mRNA expression. IL-13 is an important T cell cytokine with anti-inflammatory and immunomodulatory functions on B cells and monocytes. It is conceivable that IL-13 may act on monocytes to produce vascular permeability factor(s) involved in the pathogenesis of proteinuria in patients with relapse nephrotic syndrome.

The immune system in minimal change nephrotic syndrome

Numerous examples of abnormal immune responsiveness have been described in minimal change nephrotic syndrome (MCNS). The of MCNS with allergy and with certain genetic markers of immune responsiveness, as well as the excellent response of proteinuria to immunomodulatory agents, has suggested a causal relationship between the immunological and renal abnormalities. However, the nature of this relationship is uncertain. Before it can be clarified, the basic mechanism(s) involved in disturbed immunity in patients with MCNS must be better characterized. Studies of humoral and cellular immune function support the hypothesis that immune regulation is abnormal. However, conclusive evidence of participation by a defined immunoregulatory system in the events leading to immune dysfunction has not been obtained. Thus, considerable work remains to be done in determining the nature and cause of abnormal immunity in MCNS prior to investigating its potential role in the pathogenesis of proteinuria.

Steroid-sensitive mechanism of soluble immune response suppressor production in steroid-responsive nephrotic syndrome

Soluble immune response suppressor (SIRS), a lymphokine that suppresses antibody production and delayed type hypersensitivity in vivo, has been detected in urine and serum from certain patients with nephrotic syndrome. In the present paper, the relationship between SIRS production and nephrotic syndrome is further characterized. A striking correlation was found between detection of SIRS and the presence of steroid-responsive nephrotic syndrome (SRNS). A potential mechanism of SIRS production in SRNS patients was identified, in that lymphocytes from patients produced SIRS without requiring activation by exogenous agents, and incubation of normal lymphocytes with serum from patients activated the cells to secrete SIRS in culture. Although SIRS disappears rapidly from urine or serum after initiation of corticosteroid therapy, hydrocortisone (10(-6)-10(-7) M) did not block secretion of SIRS by activated suppressor cells. It did, however, inhibit in vitro activation of lymphocytes to produce SIRS by concanavalin A, interferon, or SRNS patient serum. The association of suppressor cell activation with SRNS and the sensitivity of both to steroids suggest that the pathogeneses of albuminuria and SIRS production are related.