Assessment of the effect of mesangial hypercellularity in childhood nephropatihies to the clinical and laboratory findings

Introduction: Mesangial cells develop from the mesenchyime and have characteristics of fibroblast and smooth muscle cells. These cells are responsible from modulation of glomerular hemodynamic factors, structural reinforcement, and phagocytosis. ?Mesangial hypercellularity?, which is a nonspecific sign indicated by presence of more than three mesangial cells in a mesangial area, might be observed in systemic diseases affecting kidneys (e.g. Henoch-Schonlein purpura) and renal glomerulonephritides (e.g. IgA and IgM nephropathies). On the other hand, the mesangial hypercellularity without any accompanying known glomerulonephritidis has been defined as ?mesangial proliferative glomerulonephritis?Purpose: The relationship between the mesangial hypercellularity in various childhood nephropathies [IgA nephropathies (isolated IgA nephropathy and Henoch-Schonlein nephritis), IgM nephropathy, and isolated mezangial proliferative glomerulonephritis] and clinical and laboratory parameters is aimed to be assessed.Method: The reports of the renal biopsies, which had been performed in the Department of Pediatric Nephrology, Dokuz Eylul University between 1993 and 2007, were evaluated retrospectively. The patients with the diagnosis of IgA nephropathy (isolated and Henoch-Schonlein nephritis), IgM nephropathies, or isolated mezangial proliferative glomerulonephritis were included. Afterwards, each nephropathy group was divided into two subgroups according to the severity of mesangial hypercellularity as ?mild? (4-6 mesangial cells in one mesangial area) and ?severe? (more than 6 mesangial cells in one mesangial area). The biochemical data (blood urea nitrogen, creatinine, albumin level, glomerular filtration rate, and proteinuria and presence of hematuria) and histopathologic findings of the patients (mesangial hypercellularity, the severity of increment of the matrix and the aggregation of immunoglobulins) were recorded. Cases with glomerulosclerosis and/or glomerular necrosis findings were excluded. The patients with Henoch-Schonlein nephritis were compared only with those having isolated IgA nephropathy since Henoch-Schonlein nephritis is a systemic disease and share similar biopsy findings with IgA nephropathy.Results: Among the evaluated 160 renal biopsy reports, 75 patients (15 IgA nephropathies, 17 Henoch-Schonlein nephritides, 17 IgM nephropathies and 26 isolated mezangial proliferative glomerulonephritides), who met the inclusion criteria of the study, were enrolled. No difference was detected between the groups regarding the severity of mesangial hypercellularity (IgA nephropathies, 10 mild and 5 severe; IgM nephropathies, 10 mild and 7 severe; and isolated mezangial proliferative glomerulonephritis, 22 mild and 4 severe; p=0.159). When the groups are compared, it was found that the patients with IgA nephropathy had hematuria (p=0.043) and the patients with IgM nephropathies had nephrotic syndrome more frequently than the other patients (p=0.01). On the other hand, when the groups were evaluated within themselves, no significant association was detected between the severity of mesangial hypercellularity and clinical and laboratory parametersIt was determined that the renal biopsy was performed earlier in the patients with Henoch-Schonlein nephritis compared to the other cases (p=0.004). Compared to the isolated IgA nephropathy group, it was found that the number of cases with severe mesangial hypercellularity was higher (p=0.002) in Henoch-Schonlein nephritis group and the level of proteinuria was more prominent in those cases (p=0.013). Additionally, when the Henoch-Schonlein nephritis patients were evaluated, the degree of proteinuria was found to be higher in patients with severe mesangial hypercellularity compared to those of showing mild mesangial hypercellularity (p=0.002). There was no difference regarding clinical and laboratory data between the patients with mild mesangial hypercellularity associated with isolated IgA nephropathy and Henoch-Schonlein nephritis. Similarly, no difference was detected regarding clinical and laboratory data between the cases with severe mesangial hypercellularity from these two groups.Conclusion: It was observed that there is no direct relation between the severity of mesangial hypercellularity and clinical and laboratory findings in pediatric cases with IgA nephropathy, IgM nephropathy, or isolated mezangial proliferative glomerulonephritis. However, when Henoch-Schonlein nephritis is compared with IgA nephropathy, it was found that the number of patients with severe mesangial hypercellularity was higher in cases with Henoch-Schonlein nephritis and the level of proteinuria was more prominent in those cases. However, no difference was detected in glomerular filtration rates and biochemical data when the levels of the mesangial hypercellularity were adjusted.Key words: Mesangial hypercellularity, IgA nephropathy, Isolated mesangial proliferative glomerulonephritis, Henoch-Schonlein nephritis