Renal survival rate of IgA nephropathy

IgA nephropathy: common nephritis leading to end-stage renal failure

IgA nephropathy (IgAN) characterized by mesangial proliferative glomerulonephritis with predominant mesangial IgA deposition is the commonest glomerulonephritis worldwide. In contrast to the initial report indicated a favorable prognosis, subsequent reports have shown a highly variable outcome leading to end-stage renal failure (ESRF) in a significant proportion of patients. Many centers report a high incidence (ranging from 10-22%) of patients with idiopathic IgAN amongst the total population of patients on maintenance dialysis. Most of these patients develop ESRF at their middle-age and hence, will pose a significant and important workload in the dialysis and transplantation programme. Because IgAN is a disease with a variable rate of progression leading to chronic renal failure amongst younger patients and with neither effective nor specific treatment, identification of the clinical and pathologic prognostic indicators for these patients is of paramount importance in planning the long-term renal replacement program.

Validation study of oxford classification of IgA nephropathy: the significance of extracapillary proliferation

BACKGROUND AND OBJECTIVES The Oxford classification of IgA nephropathy (IgAN) includes mesangial hypercellularity, endocapillary hypercellularity, segmental glomerulosclerosis (S), and tubular atrophy/interstitial fibrosis (T) as prognosticators. The value of extracapillary proliferation (Ex) was not addressed. Because the Oxford classification excludes patients with urinary protein <0.5 g/d and eGFR <30 ml/min per 1.73 m(2) at biopsy, the significance of Ex should be confirmed by validation cohorts that include more rapidly progressive cases. We present such a study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The significance of pathologic features for development end-stage renal failure (ESRF) was examined by multivariate analysis in 702 patients with IgAN. The association of Ex with kidney survival was examined by univariate analysis in 416 patients who met the Oxford criteria and 286 who did not, separately.

RESULTS

In a multivariate model, S and T were significantly associated with ESRF. With addition of Ex, not S but Ex was significant for ESRF. In univariate analysis, kidney survival was significantly lower in patients with Ex than in those without, in patients who did not meet the Oxford criteria, but such a difference was not found in patients who met it.

CONCLUSIONS

The prognostic significance of Ex was evident in our cohort. It seems that Ex did not emerge from the Oxford classification as a prognosticator because of exclusion of severe cases (eGFR <30 ml/min per 1.73 m(2)). We suggest that extracapillary proliferation be included in the next version of the Oxford classification of IgAN to widen the scope of the classification.

Genetical, histological, and clinical characteristics of IgA-negative mesangioproliferative glomerulopathy

BACKGROUND

Mesangioproliferative glomerulopathy (MesPGN) is a well-defined pathohistological entity. However, the clinical characteristics and prognosis have not been fully established in patients without immunoglobulin (Ig)A (N-IgAN) in contrast to patients with IgA nephropathy (IgAN).

METHODS

A total of 837 consecutive patients underwent renal biopsies. Among them, 465 patients were diagnosed with MesPGN by light microscopy. With immunofluorescent study and electron microscopy (EM), 344 were diagnosed as having IgAN. Among the rest, 84 patients who had no immunofluorescence evidence of IgA and no deposits in EM were defined as N-IgAN. We compared the clinical characteristics, histological findings, and genotypes of the angiotensin-converting enzyme (ACE) gene and plasminogen activator inhibitor-1 gene between IgAN and N-IgAN patients.

RESULTS

Urinary protein excretion and the degree of hematuria were significantly lower in N-IgAN than IgAN patients (0.50 vs. 0.82 g/day; P = 0.01), (1.33 vs. 2.50; P < 0.001, respectively). Creatinine clearance was higher in N-IgAN than IgAN patients (89.4 vs. 74.4 ml/min; P < 0.001). Histopathologically, N-IgAN patients had significantly less advanced glomerular and tubulointerstitial lesions than IgAN patients. Pathological grades in patients with untreated IgAN were more advanced in a time-dependent manner, whereas there was no relationship between histological grades and time of illness in N-IgAN patients. Frequency of the DD genotype of the ACE gene was significantly lower in N-IgAN (DD/ID+II = 8/76) than IgAN (24/90) patients.

CONCLUSIONS

IgA-negative MesPGN is a distinct type of glomerulopathy with a benign renal prognosis. Insertion/deletion polymorphisms of the ACE gene may play some role in the genesis and progression of MesPGN.

Accumulation of macrophages expressing myeloid-related protein 8 associated with the progression of sclerotic changes in children with IgA nephropathy

Myeloid-related protein (MRP) 8 is a calcium-binding protein of the S100 family. The renal accumulation of macrophages expressing MRP8 is associated with the inflammatory activity of glomerulonephritis. We evaluated the renal accumulation of macrophages expressing MRP8 in children with IgA nephropathy (IgAN). We collected data on 25 IgAN children who had been treated with prednisolone and divided these patients into two groups: Favorable group, consisting of 11 patients with normal urine and 6 with minor urinary abnormalities at 4.3 +/- 1.3 years after initial treatment; and Unfavorable group, consisting of 8 patients with persistent nephropathy. The pathological renal findings were compared between both groups. The second biopsy was performed at two years after first biopsy at 5.5 +/- 4.9 months from onset. In Favorable group, the glomerular accumulation of macrophages expressing MRP8, and mesangial cells expressing alpha-smooth muscle actin (alpha-SMA) were lower in the second biopsy specimens than those of the first biopsy specimens. In Unfavorable group, the glomerular accumulation of macrophages expressing MRP8 detected in the second biopsy specimens was similar to that of the first biopsy, while the number of mesangial cells expressing alpha-SMA and the index of renal sclerosis were higher in the second biopsy than in the first biopsy. The indexes of renal sclerosis were higher in children with more macrophages expressing MRP8 than in children with less macrophages expressing MRP8. Our results suggest that renal macrophages expressing MRP8 may be involved in the progression of sclerotic changes in children with IgAN.

Idiopathic IgA Nephropathy: Pathogenesis, Histopathology, and Therapeutic Options

IgA nephropathy is one of the most common causes of glomerulonephritis in the world. Proliferative and crescentic forms of IgA are found in up to 30% of cases and are associated with nephrotic-range proteinuria, accelerated hypertension, and accelerated decline toward ESRD. Despite its prevalence and clinical importance, there is no unifying nomenclature or consensus for the treatment of specific histologic subgroups. As a consequence, the development of clinically effective treatment regimens for IgA nephropathy have lagged behind other, less common forms of glomerulonephritis. Herein is reviewed the pathogenesis and histologic subtypes of IgA nephropathy and how conventional and immunosuppressive therapies have an impact on renal survival and recurrence rates. The use of known clinical risk factors for disease progression in conjunction with specific histologic features can be a guide to both induction and consolidation therapies for individual patients with IgA nephropathy.

All-trans-retinoic acid inhibits the development of mesangial proliferative glomerulonephritis in interleukin-6 transgenic mice

All-trans-retinoic acid (ATRA), a vitamin A derivative, was reported to suppress the interleukin-6 (IL-6) production and to downregulate the IL-6 receptor (IL-6R) and/or its signal transducer glycoprotein 130. We investigated the in vivo antinephritic effect of ATRA on IL-6 transgenic mice which had developed mesangial proliferative glomerulonephritis (PGN) as well as its in vitro inhibitory effect on the proliferation of rat mesangial cells. In vivo experiments on IL-6 transgenic mice showed that ATRA administration suppressed proteinuria and hematuria and reduced the IL-6 concentrations; furthermore, histological examination demonstrated that it improved PGN. In vitro experiments using rat mesangial cells demonstrated that ATRA inhibited cell growth in a dose-dependent manner within a range from 10(-4) to 10(-6) M. This inhibition by ATRA was partially counteracted by the addition of IL-6. RT-PCR assay results showed that ATRA also reduced IL-6R, but not the glycoprotein 130 expression in mesangial cells. These findings indicate that, by blocking of the IL-6 function, ATRA may be therapeutically effective in PGN.

Efficacy of multidrug therapy combined with mizoribine in children with diffuse IgA nephropathy in comparison with multidrug therapy without mizoribine and with methylprednisolone pulse therapy

AIM

To evaluate the efficacy of prednisolone, warfarin, and dipyridamole therapy combined with mizoribine (PWDM) in the treatment of diffuse immunoglobulin A (IgA) nephropathy in comparison with prednisolone, warfarin, and dipyridamole therapy without mizoribine (PWD) and with methylprednisolone pulse therapy (PWD pulse).

METHODS

We collected data on 61 patients diagnosed with diffuse IgA nephropathy, and these patients were retrospectively divided into three groups without randomization. Group A included 21 patients before 1987 who were treated with PWD for 24 months, group B included 20 patients from 1987 to 1989 who were treated with PWD pulse therapy for 24 months, and group C included 20 patients after 1990 who were treated with PWDM for 24 months. Clinical features and pathological findings in each group were analyzed retrospectively.

RESULTS

The time from initiation of therapy in group A, group B, and group C was 8.9 +/- 5.2, 8.1 +/- 3.9, and 7.7 +/- 3.8 years, respectively. At the latest follow-up examination, the mean urinary protein excretion (mg/m2/h) was 17 +/- 10 in group A, 22 +/- 20 in group B, and 6 +/- 6 in group C and had decreased significantly in group C as compared with the other groups. The activity index in all three groups was lower at the second biopsy than that at the first biopsy (5.1 +/- 0.8 vs. 6.5 +/- 2.1 in group A, p < 0.05; 5.6 +/- 0.9 vs. 6.6 +/- 1.7 in group B, p < 0.01, and 4.5 +/- 1.0 vs. 6.8 +/- 1.9 in group C, p < 0.01). The chronicity index in groups A and B at second biopsy was higher than at first biopsy (7.3 +/- 1.4 vs. 4.8 +/- 1.0 in group A, p < 0.01, and 8.1 +/- 2.0 vs. 5.3 +/- 0.9 in group B, p < 0.01), but was unchanged in group C. At the latest follow-up examination, 1 patient (4.8%) in group A, 3 patients (15%) in group B, and none (0%) in group C had renal insufficiency.

CONCLUSION

These results suggest that PWDM appears to be more effective than PWD or PWD pulse in ameliorating proteinuria and histological severity of patients with IgA nephropathy.

Urinary albumin excretion: a predictor of glomerular findings in adults with microscopic haematuria

BACKGROUND

Microscopic haematuria without proteinuria is a common clinical finding. When urological causes are excluded, usual findings on renal biopsy are IgA nephropathy (which can progress to end-stage renal failure) or thin basement membrane nephropathy (which has an excellent prognosis). A non-invasive test to discriminate between the two would be useful.

AIM

To examine the value of measurement of urinary albumin excretion in discriminating glomerular causes of microscopic haematuria in patients without proteinuria on urine dipstick tests.

DESIGN

Single-centre retrospective cross-sectional observational study.

METHODS

Adult patients who underwent renal biopsy for microscopic haematuria over a 6-year period from January 1994 were identified. Study entry required normal renal function, no proteinuria detected by dipstick, and urinary albumin excretion <300 mg/24 h. Patients with IgA nephropathy had follow-up for a mean of 58 months after biopsy.

RESULTS

Of 169 patients fulfilling study criteria, 119 (70%) had normoalbuminuria (<30 mg/24 h); 52 (30%) had microalbuminuria (30-299 mg/24 h). Of those with normoalbuminuria, 106 (89%) had thin basement membrane nephropathy or no glomerular abnormality. Thirteen (11%) had IgA nephropathy, and of 12 of these followed-up for a mean 64 months, none developed overt, dipstick-positive proteinuria. In contrast, 24 (48%) of those with microalbuminuria had IgA nephropathy, and of 22 followed-up for a mean 55 months, five developed overt proteinuria.

DISCUSSION

Urinary albumin excretion is an indicator of likely glomerular findings in microscopic haematuria, and may influence whether a renal biopsy is necessary.

Natural history of idiopathic IgA nephropathy: role of clinical and histological prognostic factors

Idiopathic immunoglobulin A nephropathy is characterized by an extreme variability in clinical course and sometimes by the unpredictability of the ultimate outcome. Among the numerous studies published in the last 15 years that have calculated the actuarial renal survival and tried to individuate the prognostic role of the clinical and histological features present at the onset of the disease or the time of biopsy, we chose to analyze critically the results of the most valid (30 studies). Actuarial renal survival at 10 years in adults was between 80% and 85% in most of the European and Asian studies, but it was less in studies from the United States and exceeded 90% in the few studies of children. Concordance existed in this selected literature that impairment of renal function, severe proteinuria, and arterial hypertension are the strongest and more reliable clinical predictors of an unfavorable outcome. However, analysis of the prognostic value of morphological lesions was more difficult because they have been characterized in some studies using an overall score or histological classes of progressively more severe involvement and, in others, using a semiquantitative grading of individual glomerular, tubular, interstitial, and vascular changes. In adult patients, a high score of glomerular and tubulointerstitial lesions, corresponding to classes IV and V of the Lee or Haas classifications, predicted a more rapid progression. When single lesions were analyzed separately, glomerulosclerosis and interstitial fibrosis appeared to be the strongest, most reliable predictors of unfavorable prognosis. More controversial was the role of crescents and capsular adhesions. None of the immunohistological features was found to be a risk factor for progression in the more accurate statistical analyses. The same histological features predicted outcome in children, although the severity of lesions at the time of biopsy was usually less than that in adults. However, in the single patient, even the evaluation of these prognostic markers sometimes fails to correctly predict outcome, probably because of the heterogeneity of the disease and the discontinuous activity of some injuring mechanisms during its course.

Effect of gender on the progression of nondiabetic renal disease: a meta-analysis

There is previously published evidence that male gender is associated with a more rapid rate of progression of nondiabetic chronic renal disease. However, some investigators have concluded that no such association exists. To help resolve this issue, a meta-analysis was performed using 68 studies that met defined criteria and contained a total of 11,345 patients to evaluate the effect of gender on the progression of nondiabetic chronic renal disease. The results indicate that men with chronic renal disease of various etiologies show a more rapid decline in renal function with time than do women.

Corticosteroids in IgA nephropathy: a randomised controlled trial

BACKGROUND

IgA nephropathy is progressive in most cases and has no established therapy. In this randomised trial, we assessed the efficacy and safety of a 6-month course of steroids in this disorder.

METHODS

Between July, 1987, and September, 1995, we enrolled 86 consecutive patients from seven renal units in Italy. Eligible patients had biopsy-proven IgA nephropathy, urine protein excretion of 1.0-3.5 g daily, and plasma creatinine concentrations of 133 micromol/L (1.5 mg/dL) or less. Patients were randomly assigned either supportive therapy alone or steroid treatment (intravenous methylprednisolone 1 g per day for 3 consecutive days at the beginning of months 1, 3, and 5, plus oral prednisone 0.5 mg/kg on alternate days for 6 months). The primary endpoint was deterioration in renal function defined as a 50% or 100% increase in plasma creatinine concentration from baseline. Analyses were by intention to treat.

FINDINGS

Nine of 43 patients in the steroid group and 14 of 43 in the control group reached the primary endpoint (a 50% increase in plasma creatinine) by year 5 of follow-up (p<0.048). Factors influencing renal survival were vascular sclerosis (relative risk for 1-point increase in score 1.53, p=0.0347), female sex (0.22, p=0.0163), and steroid therapy (0.41, p=0.0439). All 43 patients assigned steroids completed the treatment without experiencing any important side-effects.

INTERPRETATION

A 6-month course of steroid treatment protected against deterioration in renal function in IgA nephropathy with no notable adverse effects during follow-up. An increase in urinary protein excretion could be a marker indicating the need for a second course of steroid therapy.

The impact of gender on the progression of chronic renal disease

Observations in experimental animals and in humans have shown that the rate of progression of renal disease is influenced by gender. Deterioration of renal function in patients with chronic renal disease is more rapid in men than in women, independent of differences in blood pressure or serum cholesterol levels. In addition to genetically determined differences between the sexes in renal structure and function, sex hormones may directly influence many of the processes implicated in the pathogenesis of renal disease progression. Potential mechanisms include receptor-mediated effects of sex hormones on glomerular hemodynamics and mesangial cell proliferation and matrix accumulation as well as effects on the synthesis and release of cytokines, vasoactive agents, and growth factors. In addition, estrogens may exert potent antioxidant actions in the mesangial microenvironment, which may contribute to the protective effect of female gender.

Significance of the evaluation of asymptomatic microscopic haematuria in young men

OBJECTIVE

To evaluate the extent of diagnostic evaluation that is necessary in young men with asymptomatic microscopic haematuria.

PATIENTS AND METHODS

A group of 157 men (mean age 24.8 years [range 18-53]) who presented with asymptomatic haematuria were investigated with repeated urine analysis. Addis count, urinary cultures, blood tests, ultrasonography, pyelography, cystourethroscopy and finally renal biopsy.

RESULTS

The results showed pathological findings in 31.2% of patients. Of the 157 individuals, 33.1% did not complete the study. In 14.6% urological disease was found, including two patients with urothelial cancer. Renal biopsy detected glomerulopathy in 16.5% of all patients. IgA nephritis being the most common diagnosis (42% of all biopsies).

CONCLUSION

Even in young patients, microscopic haematuria should be investigated and followed thoroughly. Renal biopsy seems to be optional: once a diagnosis is established repeated and unnecessary examinations can be avoided.

Development of renal failure in IgA nephropathy: the importance of interstitial infiltration and deposition of fibrinogen

We analyzed renal biopsy specimens of 60 patients with IgA nephropathy, 34 male and 26 female, aged 32, 8 +/- 9, 1. Patients were divided into 5 classes according to the morphological classification proposed on the basis of WHO criteria: 1, minimal lesions; 2, minor changes; 3, focal and segmental glomerulonephritis; 4, diffuse mesangial proliferation; and 5, sclerotic changes. Interstitial infiltration on optical microscopy and fibrinogen deposition on immunofluorescent microscopy were graded using a semiquantitative score. Clinical features (hypertension, proteinuria, erythruria/hematuria, renal function) were taken into consideration. The Mann-Whitney test was used for comparison of results between different classes. Classes 1 and 2 were younger (p < 0.01) and had significantly better renal function than classes 3 and 4. Proteinuria was significantly higher in classes 2 and 3 (p < 0.001) than the others. Macroscopic hematuria was more frequent in classes 1 and 2. Hypertension was absent in class 1 and correlated with the severity of histologic changes. Interstitial infiltration was absent in class 1 and also correlated with the degree of histological changes, but in contrast, fibrinogen deposits were more severe in earlier histological classes.

Quantitative study of mesangial injury with proteinuria induced by monoclonal antibody 1-22-3

Murine MoAb 1-22-3 has already been reported to bind to the mesangial cell surface and to cause transient proteinuria and mesangial morphological changes characterized by mesangiolysis, subsequent mesangial cell proliferation and mesangial matrix increase by a single i.v. injection. In this study, MoAb-induced glomerulopathy was quantitatively analysed. No correlation between the severity of mesangial morphological changes and the degree of proteinuria was detected (r = 0.190). The minimum dose injected to induce abnormal proteinuria was 25 micrograms. This dose corresponded to 1.79 micrograms/2 kidneys 30 min after MoAb injection. The highest average level of proteinuria was observed in rats injected with 500 micrograms of MoAb, and less proteinuria was observed in rats injected with 10.0, 5.0 and 2.0 mg. Although the amounts of kidney-fixing MoAb and the subsequent deposition of rat C3 in the high-dose-injected group were larger than in the 500 micrograms injected group, the numbers of infiltrating inflammatory cells were the same in both groups. No correlations between the degrees of such mediators and proteinuria were observed.

Follow-up of renal function and urinary protein excretion in childhood IgA nephropathy

Renal haemodynamics and urinary protein excretion (UPE) were investigated in 36 patients with IgA nephropathy more than 3 years after renal biopsy (mean interval 6.3 +/- 0.5 years). At follow-up, 39% of patients had a reduced glomerular filtration rate (GFR) and 11% endstage renal failure. Twenty-five percent had albuminuria, and a further 25% microalbuminuria. All albuminuric patients had GFRs below the mean, and 78% of the albuminurics had a reduced GFR. However, non-albuminurics also had decreased GFRs and GFR tended to fall with the duration of the disease in this group of patients. On comparing the histological changes in the biopsies with haemodynamic and UPE studies performed 6 years later, we found significant correlations between the extent of segmental glomerular sclerosis and GFR, effective renal plasma flow, urinary albumin and IgG excretion, respectively. Histological grading correlated with the same variables. Of the 4 uraemic patients, 2 were nephrotic at presentation, while the other 2 had a nephritic onset of disease and later developed heavy proteinuria. Three of their biopsies showed > or = 10% segmental glomerulosclerosis. Juvenile IgA nephropathy is not a harmless disease. Our results indicate that these children should be carefully monitored with adequate GFR measurements and urine protein analyses.

Influence of clinical and histological features on actuarial renal survival in adult patients with idiopathic IgA nephropathy, membranous nephropathy, and membranoproliferative glomerulonephritis: survey of the recent literature

The most recent studies, using the actuarial life-table technique, of the problem of long-term renal outcome and the factors that influence it in adult patients with one of the three most common types of chronic idiopathic immune complexes-mediated glomerulonephritis (IgA nephropathy [IgAN], membranous nephropathy [MN], and type I membranoproliferative glomerulonephritis [MPGN]) are reviewed. In the last decade, renal survival 10 years after onset has become similar to adult patients with idiopathic IgAN (80% to 87%) and idiopathic MN (75% to 83%), because of improvement of the renal survival of patients with MN. Renal survival at 10 years is worse for adult patients with idiopathic type I MPGN (60% to 64%). There is no substantial difference in the average renal survival times between different geographical regions, with the exception of a better prognosis for idiopathic MN in Japan. The presenting clinical factors that most strongly predict subsequent poor outcome are similar for the three types of glomerulonephritis and are rather nonspecific: (1) severe proteinuria, (2) impairment of renal function, and (3) arterial hypertension. As for the histological features, the most powerful predictor of subsequent progression in all three types of glomerulonephritis is tubulointerstitial damage, suggesting that a cell-mediated immune process believed to occur there may independently influence outcome in glomerular diseases.

Extrarenal cytokines modulate the glomerular response to IgA immune complexes

Clinical episodes of IgA nephropathy coincide recurrently with microbial infections. Cytokines produced during such infections may play a role in the pathogenesis of IgA-associated glomerulonephritis. To test this hypothesis, we examined the influence of passively administered proinflammatory cytokines (IL-1, IFN-gamma and IL-6) on the development of glomerulonephritis in an experimental model of IgA nephropathy. Glomerular IgA immune deposits were induced in mice by administration of IgA anti-phosphorylcholine (PC) with either a PC-containing carbohydrate antigen of Pneumococcal C polysaccharide (PnC) or a protein antigen of PC-conjugated bovine serum albumin (PC-BSA). The effect of IL-1 on the IgA-PC-BSA induced glomerular changes resulted in an increase of mesangial hypercellularity that was associated with mild proteinuria and hematuria. Mice treated with IL-1 and IgA-PnC developed diffuse proliferative glomerulonephritis with proteinuria and hematuria. In contrast, IL-6 treatment with IgA-PC-BSA of IgA-PnC failed to exert any significant renal effect. The combination of IL-6 and IL-1, however, intensified the mesangial hypercellularity of the IgA-PC-BSA, and induced severe proliferative glomerulonephritis with inflammatory monocytes and neutrophils infiltrates in the IgA-PnC treated mice. These glomerular changes were also accompanied by increased proteinuria and hematuria. Similarly, the combination of IFN with IL-1 produced histologic changes and compromised renal function more than IFN or IL-1 exerted independently. These results suggest that extrarenal cytokines influence the renal response to IgA immune deposits. We also conclude that a synergy of multiple cytokines and nephritogenic antigens immobilized in glomerular IgA immune deposits may lead to rapid progression of IgA-associated glomerulonephritis.

Renal histological changes in relation to renal function and urinary protein excretion in IgA nephropathy

Renal function and urinary protein excretion (UPE) were investigated at the time of kidney biopsy in 24 children with IgA nephropathy. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by clearances of inulin and para-aminohippuric acid. For UPE albumin, IgG, beta 2 microglobulin, and creatinine were analysed. Glomerular global/segmental sclerosis and crescents in the biopsy specimens were assessed, and glomerular and tubulointerstitial changes classified on a five degree scale. The patients with tubulointerstitial or mesangial biopsy changes or glomerular sclerosis had significantly lower GFR than those without corresponding lesions. Patients with segmental sclerosis also had higher excretion rates of IgG, which increased with increasing segmental sclerosis. Six patients had GFRs below 2SD of the controls. Within the group of patients with reduced GFR overt albuminuria, a raised excretion rate of IgG, interstitial fibrosis, and advanced mesangial lesions were more frequent. A rising excretion rate of IgG seems to indicate both reduced GFR and increasing segmental glomerulosclerosis and may be a marker of progressive disease.

Long-term follow up of renal function in IgA nephropathy

Fifty one children with IgA nephropathy verified at biopsy have been followed up clinically and functionally for 0.4-16.8 years from the onset of symptoms. Renal function was evaluated by determining the glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) from the clearances of inulin and para-aminohippuric acid. Fifteen (29%) of the children had raised serum creatinine concentrations at the onset. Mean GFR was significantly lower than that of controls at the first investigation. During the follow up GFR and ERPF decreased and were significantly lower than in the controls after eight years of disease. The significant fall in renal function was found in children with proteinuria and especially in boys, in whom GFR and ERPF decreased from a mean (SEM) of 117 (5) and 616 (31) at 2.8 years to 97 (6) and 509 (36) ml/min/1.73 m2 at 7.5 years. Patients with raised serum creatinine concentrations at the onset had significantly lower GFRs, and patients with macroscopic haematuria at this time did not show decreased renal function at follow up. In conclusion, children with IgA nephropathy do not seem to have a benign clinical course. Boys with proteinuria show a significant decrease in renal function during follow up.

Urinary protein excretion and renal function in children with IgA nephropathy

Renal haemodynamics and the pattern of urinary protein excretion were studied in 38 children (21 boys, 17 girls) with biopsy-proven IgA nephropathy (IgAN), 0.4-16.8 (median 5.3) years after onset of the disease. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were evaluated by clearances of inulin and para-aminohippuric acid. Serum and urinary albumin, IgG and beta 2-microglobulin (beta 2 mu) were determined and the excretion rates, clearances, and fractional clearances were calculated. The patients were grouped according to the type and the amount of proteinuria. Mean GFR and ERPF were significantly decreased (107 +/- 3 and 580 +/- 17 ml/min per 1.73 m2, respectively) versus controls (119 +/- 2 and 627 +/- 14 ml/min per 1.73 m2, respectively). Grouped according to albumin excretion rates, non-albuminuric patients had normal GFR, while mean GFR was reduced in patients with micro-albuminuria (106 +/- 3 ml/min per 1.73 m2) and albuminuric patients (92 +/- 7 ml/min per 1.73 m2). IgG excretion increased with increasing albuminuria, but the selectivity index was lower in albuminuric patients than in patients with micro-albuminuria. Albuminuric patients had also higher blood pressure than those with micro-albuminuria. beta 2 mu excretion did not discriminate between patients with impaired renal function. The results suggest that childhood IgAN is not a benign kidney disease. After a median duration of 5 years of the disease a number of children had impaired renal function. Mean GFR was reduced most in the albuminuric patients but was also decreased in micro-albuminuric patients, indicating that micro-albuminuria may be a predictor of more severe disease.

A retrospective analysis of the natural history of primary IgA nephropathy worldwide

The worldwide medical literature was reviewed to determine whether the prevalence, clinical presentation, and immunohistologic findings of primary IgA nephropathy were related to geographic areas. A total of 68 reports containing detailed clinical histories and laboratory findings were analyzed. The selected articles were grouped according to their geographic origin: Asia, Australia, Europe, and North America (Canada and the United States). Analysis of the data showed that IgA nephropathy is more frequent in the Asian area than in Australia, Europe, and North America. The male/female ratio indicates that males are more likely to be affected by the disease, particularly in the second and third decade of life. The appearance of the disease is characterized by microscopic hematuria and mild proteinuria in Asians, whereas gross hematuria is more frequent in American and European patients. At the time of renal biopsy, fixed microscopic hematuria is detected in a high percentage of patients in Asia and Europe, whereas macroscopic hematuria is more frequent in American patients. Mild renal lesions occur more frequently in Asian patients, while severe renal lesions and a high frequency of immunoglobulin and complement deposits are present in American and European patients. Differences encountered in this retrospective analysis may be influenced by two important factors: (1) the absence of urinalysis screening programs in the schools of Europe and North America, and (2) the different approaches to renal biopsy in the eastern and western parts of the world. Due to the high rate of renal insufficiency and end-stage kidney disease in European and North American patients with IgA nephropathy, it is recommended that a program of urinalysis screening in schools and an appropriate renal biopsy policy be adopted in the western areas of the world.

Alternate-day prednisone therapy in children with IgA-associated nephritis

IgA nephropathy (IgAN) leads to renal failure in up to 30% of affected children and adults. There is currently no consensus on therapy in IgAN. Six patients with risk factors for disease progression were identified based on clinical or histologic findings. These patients were treated with alternate-day prednisone for 12 to 60 (mean, 36) months and followed for 28 to 60 (mean, 54) months. Follow-up biopsies were available in four patients. At last examination all treated patients had normal urinalysis and serum creatinine level. Follow-up biopsies showed stable or improved glomerular histology in three of four patients. One patient had a slight worsening of the interstitial disease. No steroid toxicity was observed. The outcome of these treated patients was compared with that of 15 comparable patients from another center who received no treatment and with patients from two published clinical pathology series. A normal urinalysis was found at follow-up in all treated patients, compared with one of 15 untreated patients (P = 0.003). None of the patients in the published series with comparable disease had normal urinalysis at follow-up. End-stage renal disease or renal insufficiency occurred in seven of 15 untreated and no treated patients (P = 0.19). The data strongly support the need for a prospective control trial of prednisone therapy in IgAN.

Proteinuria in IgA nephropathy

Clinicopathological data in 74 patients with IgA nephropathy were analyzed with special attention to level of proteinuria and its prognostic significance in this disease. Excretion rates exceeding 3 g per day (heavy), in the range of 1 to 2.9 g (moderate) and under 1 g per day (mild) each occurred in approximately equal proportions of patients. One-sixth of those with more than 1 g developed end-stage renal failure, while serum creatinine never exceeded 2 mg/dl in any with mild proteinuria. "Renal survival" (serum creatinine of 2 mg/dl or less) at five years after presentation was 100% in patients with persistently mild proteinuria, 87% in those whose protein excretion reached the moderate range, and 69% when heavy or nephrotic range proteinuria developed. Of significance, only rarely did mild proteinuria at presentation increase to higher levels. A correlation existed between level of protein excretion and severity of mesangial, segmental or global proliferation, glomerulosclerosis, podocyte effacement, interstitial infiltration, tubular atrophy and vascular sclerosis, even in patients with unimpaired renal function. Moderate or heavy proteinuria typically preceded the onset of hypertension and occurred prior to the development of renal insufficiency. Our results underscore magnitude of proteinuria as an early marker of glomerular damage in the prognosis of IgA nephropathy.

Anti-alpha-galactosyl antibodies and immune complexes in children with Henoch-Schönlein purpura or IgA nephropathy

Episodes of hematuria in IgA nephropathy or Henoch-Schönlein purpura are frequently associated with microbial infections. Some of those infectious agents bear alpha-galactosyl residues on their cell surface. These observations prompted us to determine, by passive hemagglutination, the titers of natural anti-galactosyl antibodies in the serum of children presenting with Henoch-Schönlein purpura (10 cases) or IgA nephropathy (7 cases). Antibody titers of normal subjects (103 cases), children with a pharyngitis of unknown etiology (7 cases), and children exhibiting mesangial IgA deposits but no hematuria at the time of testing (6 cases) ranged from 1:20 to 1:80. Elevated titers (greater than 1:80) were observed in nine of 11 patients with mesangial IgA deposits and micro- or macroscopic hematuria, in nine of 19 children with other evolutive glomerular diseases (5 cases of acute glomerulonephritis and 4 cases of minimal change disease), and in most subjects presenting with a M. pneumoniae (4/5 cases) or a E. Coli (4/5 cases) infection. Antibody titers decreased after incubation of normal and pathological sera with D-galactose (10 mM) or with alpha-galactosyl-glucoside (10 mM), but not with D-glucose (10 mM). The anti-alpha-galactosyl antibodies purified, by affinity chromatography, from sera of 10 normal children, 10 pathological controls and four children with mesangial IgA deposits without hematuria belonged to IgG class. In contrast, both IgG and IgA anti-alpha-galactosyl antibodies were detected in six of six patients with mesangial IgA deposits and hematuria. The IgA content of immune complexes detected in those patients decreased after incubation of sera with alpha-galactosyl-glucoside, but not with D-glucose.(ABSTRACT TRUNCATED AT 250 WORDS)