Yoshiharu Nishitani

Plasma and Urinary Levels of Adrenomedullin in Chronic Glomerulonephritis Patients with Proteinuria

In this study, we measured levels of plasma and urinary adrenomedullin (AM) in 37 patients with chronic glomerulonephritis including minimal change nephrotic syndrome, focal segmental glomerulosclerosis or membranous nephropathy that can induce severe proteinuria. Thirty-nine healthy volunteers were enrolled as controls. Plasma and urinary AM levels were measured by an AM-specific radioimmunoassay. Plasma AM concentrations were higher and urinary AM levels were lower in patients with chronic glomerulonephritis than in healthy volunteers. Patients were divided into two groups according to urinary excretion of protein for 24 h (UPro, g/day) which reflects the disease activity or glomerular damage of the glomerulonephritis (group I: Upro < 1, group II: Upro ≥ 1). Plasma AM levels positively and urinary AM-levels negatively correlated with the degree of proteinuria. These results suggest that plasma and urinary AM levels in patients with chronic glomerulonephritis reflect the disease activity or glomerular damage represented by the degree of proteinuria.

Adrenomedullin Gene Transcription Is Decreased in Peripheral Blood Mononuclear Cells of Patients with IgA Nephropathy

We measured mRNA levels of adrenomedullin (AM), C-type natriuretic peptide (CNP), vascular endothelial growth factor (VEGF), interleukin 1β (IL-1β) and interleukin 6 (IL-6) in peripheral blood mononuclear cells (PBMC) of patients with IgA nephropathy. To evaluate these mRNA levels, we employed a real-time quantitative PCR method which was performed using a hybridization probe labeled with two fluorescence dyes. This strategy was found to afford the standard curves with a high correlation, suggesting that this method is useful for evaluations of mRNA levels. By this method, levels of AM, CNP, VEGF, IL-1β and IL-6 mRNA in PBMC of 49 IgA nephropathy patients and 35 healthy volunteers were evaluated. Among the mRNAs examined, AM mRNA levels were significantly lower in severe-grade than in mild-grade IgA nephropathy patients. Furthermore, AM mRNA levels correlated with CNP mRNA levels in PBMC of patients with IgA nephropathy, and each peptide generated from these mRNAs has antiproliferative effects on mesangial cells. These data indicate that gene expression of AM in PBMC is regulated according to the pathophysiological states of IgA nephropathy and that decreased AM production may contribute to the progression of IgA nephropathy.

Imbalance between interleukin-6 and adrenomedullin mRNA levels in peripheral blood mononuclear cells of patients with lupus nephritis

In this study, we measured the mRNA levels of adrenomedullin (AM), C‐type natriuretic peptide, vascular endothelial growth factor, interleukin‐1β (IL‐1β) and interleukin‐6 (IL‐6) in peripheral blood mononuclear cells (PBMC) of 34 patients with lupus nephritis (LN) (15 active and 19 inactive) and 30 healthy volunteers. mRNA levels were measured using a real‐time quantitative PCR method. Compared with healthy volunteers, IL‐6 mRNA levels were elevated in LN patients (P < 0·005), while AM mRNA levels were decreased (P < 0·05). Also, IL‐6 mRNA levels were higher and AM mRNA levels lower in active LN patients compared with inactive LN patients. In addition, IL‐6 mRNA levels positively correlated and AM mRNA levels negatively correlated with SLE disease activity index and laboratory findings, such as blood urea nitrogen, serum creatinine, 50% haemolytic unit of complement and urinary excretion of protein over 24 h. Furthermore, IL‐6 mRNA levels were negatively correlated with AM mRNA levels within the same LN patients. With regard to pathological findings, our results showed that IL‐6 mRNA levels were higher, and AM mRNA levels significantly lower in patients with a high activity index compared to those with a low activity index. Following treatment with prednisolone, IL‐6 mRNA levels in active LN patients decreased and AM mRNA levels increased to levels comparable to those in inactive LN and healthy volunteers. In vitro studies further demonstrated that elevated IL‐6 mRNA levels in active LN patient PBMC were suppressed by the addition of adrenomedullin. Our results suggest that an imbalance between IL‐6 and AM levels may play an important role in the progression of SLE, and that the mRNA levels of these genes in PBMC may be used as a disease activity index for SLE.

Prediction of corticosteroid responsiveness based on fibroblast-specific protein 1 (FSP1) in patients with IgA nephropathy

BACKGROUND Corticosteroids are frequently used to treat patients with active IgA nephropathy (IgAN); however, there have been few reports describing factors that are predictive of the response to corticosteroid treatment. The purpose of this study is to determine the extent to which fibroblast-specific protein 1-positive (FSP1(+)) cells are predictive of corticosteroid responsiveness in patients with IgAN. METHODS Fifty biopsy-proven IgAN patients who received corticosteroid therapy were enrolled and followed for 7.1 +/- 3.0 years. FSP1(+) cells were identified using an anti-FSP1 antibody. RESULTS Twelve patients showed progression of renal impairment or no reduction of urinary protein (non-responders) after steroid therapy. In the remaining 38 patients, renal function was stable during follow-up, and their urinary protein declined to <1.0 g/day (responders). Serum creatinine, estimated GFR, severity of mesangial proliferation, percent glomerulosclerosis/total glomeruli, extent of interstitial damage and FSP1(+) cell number were all significantly higher in non-responders than in responders. Cox regression analysis using two covariates with every possible combination of factors indicated that FSP1(+) cell number was the strongest and most significant predictor of corticosteroid responsiveness. When IgAN patients had >32.6 FSP1(+) cells/HPF at diagnosis, they were the more likely to show steroid resistance. CONCLUSION FSP1(+) cell number can serve as an excellent predictor of corticosteroid responsiveness in patients with IgAN.

Association of Interleukin-1 Receptor Antagonist Gene Polymorphism with IgA Nephropathy

It is evident that cytokines play an important role in the pathogenesis as well as disease progression of IgA nephropathy (IgAN). Several gene polymorphisms of the pertinent cytokines have an influence on the level of cytokine production. Interleukin-1 receptor antagonist (IL-1ra) gene polymorphism has been found to affect disease susceptibility and activity in several inflammatory diseases. In the present study, we analyzed polymorphism of the variable number tandem repeat (VNTR) of IL-1ra in patients diagnosed as having IgAN (n = 106) and normal controls (n = 74). The allele frequency of IL-1ra polymorphism in IgAN patients was not statistically different from that of the control group. There was no significant difference in the carriage rate of the two-repeat allele (IL1RN*2) between IgAN patients and the control group (8.5 vs. 6.8%). The carriage rate of IL1RN*2 was significantly higher in IgAN patients with severe proteinuria (≧1.6 g/day) or increased serum creatinine level (≧2.0 mg/dl; p < 0.05). Furthermore, the carriage rate of IL1RN*2 was significantly higher in patients with severe mesangial cell proliferation (p < 0.01). Our results suggest that IL-1ra polymorphisms are not associated with the development of IgAN in Japanese patients but the presence of IL1RN*2 may be associated with increased disease activity.

Increased urinary levels of adrenomedullin in patients with cystitis

In this study, we examined urinary levels of adrenomedullin (AM) in 18 healthy volunteers and 18 patients with cystitis. We also compared urinary levels of AM in 11 patients with cystitis before and after antibiotic treatment. Urinary AM concentrations were measured by a radioimmunoassay specific for human AM. Urinary AM levels in patients with cystitis were significantly elevated compared with those of healthy volunteers and correlated positively with the number of urine leukocytes. By antibiotic treatment, urinary AM levels significantly decreased as compared with before the treatment. By RNA blot analysis of AM transcript, we detected significant levels of AM mRNA in canine urinary bladder and ureter. Intravenous administration of lipopolysaccharide elevated the AM mRNA level in the urinary bladder. These data suggest that infection and inflammation stimulate AM production in the urinary tract, which results in increased urinary AM levels in patients with cystitis. Based on these results, it is deduced that AM participates in the pathophysiology of cystitis, and its urinary level could be used as an index of the degree of cystitis.