Current distribution pattern of biopsy-proven glomerular disease in Salvador, Brazil, 40 years after an initial assessment

INTRODUCTION

A report on the prevalence of glomerular disease diagnosed via renal biopsy in Salvador, BA, Brazil was published in 1973 and showed a predominance of membranoproliferative glomerulonephritis, which was frequently associated with hepatosplenic schistosomiasis.

OBJECTIVE

In this study, we investigate the potential changes in the distribution of glomerular diseases after a period of important epidemiological transition in Brazil.

METHODS

Pathology reports of all patients subjected to kidney biopsy from 2003 to 2015 in a referral nephrology service were reviewed. Clinical, laboratorial and pathological diagnoses were collected for analysis. Histological slides of the biopsies performed between 2003 and 2006 were reviewed to examine the accuracy of the estimates based on the pathology reports.

RESULTS

Among the biopsies performed during the time period, 1,312 met the inclusion criteria for the study. Focal and segmental glomerulosclerosis was the most prevalent diagnosis, followed by lupus nephritis. However, a trend toward a decrease in the prevalence of focal and segmental glomerulosclerosis was detected (p < 0.05), and an increase in lupus (p < 0.0001) and membranous glomerulonephritis (p < 0.005) was observed.

CONCLUSION

The data presented herein suggest the occurrence of changes in the distribution of nephrological diseases in Salvador, Brazil. The disease that was most prevalent shifted from membranoproliferative glomerulonephritis to focal and segmental glomerulosclerosis from 1975 to 2006 and from focal and segmental glomerulosclerosis to lupus nephritis from 2006 to 2015.

Schistosomal glomerulopathy and changes in the distribution of histological patterns of glomerular diseases in Bahia, Brazil

Distinct patterns of glomerular lesions, including membranoproliferative glomerulonephritis and focal segmental glomerulosclerosis, are associated with infection by Schistosoma mansoni or Schistosoma japonicum. Evidence suggests that immune complex deposition is the main mechanism underlying the different forms of schistosomal glomerulonephritis and that immune complex deposition may be intensified by portal hypertension. The relationship between focal segmental glomerulosclerosis and schistosomiasis remains poorly understood. A clinicopathologic classification of schistosomal glomerulopathies was proposed in 1992 by the African Association of Nephrology. In Brazil, mass treatment with oral medications has led to a decrease in the occurrence of schistosomal glomerulopathy. In a survey of renal biopsies performed in Salvador, Brazil, from 2003-2009, only 24 (4%) patients were identified as positive for S. mansoni infection. Among these patients, only one had the hepatosplenic form of the disease. Focal segmental glomerulosclerosis was found in seven patients and membranoproliferative glomerulonephritis was found in four patients. Although retrospective studies on the prevalence of renal diseases based on kidney biopsies may be influenced by many patient selection biases, a change in the distribution of glomerulopathies associated with nephrotic syndrome was observed along with a decline in the occurrence of severe forms of schistosomiasis.

Interstitial expression of angiotensin II and AT1 receptor are increased in patients with progressive glomerulopathies

In animal models, interstitial angiotensin II (ang II) and AT1 receptor (AT1R) are key mediators of renal inflammation and fibrosis in progressive chronic nephropathies. We hypothesized that these molecules were overexpressed in patients with progressive glomerulopathies. In this observational retrospective study, we described the expression of ang II and AT1R by immunohistochemistry in kidney biopsies of 7 patients with minimal change disease (MCD) and in 25 patients with progressive glomerulopathies (PGPs). Proteinuria, serum albumin, and serum creatinine were not statistically different between MCD and PGP patients. Total expression of ang II and AT1R was not statistically different between MCD (108.7+/-11.5 and 73.2+/-13.6 cells/mm(2), respectively) and PGN patients (100.7+/-9.0 and 157.7+/-13.8 cells/mm(2), respectively; p>0.05). Yet, interstitial expression of ang II and AT1R (91.6+/-16.0 and 45.6+/-5.4 cells/mm(2), respectively) was higher in patients with PGN than in those with MCD (22.0+/-4.1 and 17.9+/-2.9 cells/mm(2), respectively, p<0.05), as was the proportion of interstitial fibrosis (11.0+/-0.7% versus 6.1+/-1.2%, p<005). In patients with MCD, ang II and AT1R expressions predominate in the tubular compartment (52% and 36% of the positive cells, respectively). In those with PGP, the interstitial expression of ang II and AT1R predominates (58% and 45%, respectively). In conclusion, interstitial expression of ang II and AT1R is increased in patients with progressive glomerulopathies. The relationship of these results and interstitial fibrosis and disease progression in humans warrants further investigations.

Primary glomerular diseases in Brazil (1979-1999): is the frequency of focal and segmental glomerulosclerosis increasing?

AIMS

Different patterns of glomerulonephritis (GN) are reported from all over the world and the occurrence of primary GN is changing in the course of time. We report the frequencies of primary GN in a major teaching hospital in Brazil, from 1979-1999.

METHODS

The case files of renal biopsies of primary GN were reviewed. The included patients were > 14 years of age, with native kidneys, and the specimens were examined with at least light and immunofluorescence microscopy. We excluded biopsy results of patients with any kind of known secondary glomerular involvement. Differences in proportions of diagnoses between the periods over time were evaluated using Chi-square test for trend.

RESULTS

We considered 943 patients for the analysis. Focal and segmental glomerulosclerosis (FSGS) was the most common lesion (n = 279), followed by membranous GN (n = 140), membranoproliferative type I GN (n = 109) and IgA nephropathy (n = 109). FSGS (32.1%) was the most frequent diagnosis among nephrotic patients whereas IgAN (29.4%) predominated in non-nephrotic ones. The occurrence of FSGS increased from the earlier to the later periods: 22.3% (1979-1983), 23.7% (1984-1988), 35.7% (1989-1993), 33.9% (1994-1999), p < 0.05. The increase in frequency of FSGS was proportionally higher in non-nephrotic patients and FSGS became as common as IgA nephropathy in this group (31.6% and 28.0%, respectively) from 1994-1999.

CONCLUSIONS

FSGS was the most common pattern of primary glomerulonephritis and its relative frequency seems to be increasing in biopsied patients over time. The reasons for this behavior are unclear and warrant further investigations.

Comparative study of IgA nephropathy with and without crescents

Glomerular crescents were analyzed as a prognostic factor in retrospectively reviewed data from 144 patients with biopsy-proven IgA nephropathy. Crescents were found in 26 (18%) patients, and detected in 2 to 100% of glomeruli in each specimen. In 5% of the patients more than 50% of the glomeruli were affected. Thirty patients with IgA nephropathy without crescents were studied as a control group. Mean age was 30.3 +/- 9.4 and 30.2 +/- 12.0 years for the patients with and without crescents, respectively, and males prevailed in both groups. The length of follow-up was 23.2 +/- 41.6 months for patients with crescents and 29.3 +/- 35.3 months for patients without crescents. Eighty percent of the patients with crescents were hypertensive, compared to 27% of the non-crescent control group (P < 0.05). Mean serum creatinine at the time of diagnosis was 3.9 +/- 2.9 and 1.9 +/- 2.1 mg/dl for the patients with and without crescents, respectively. Initial urinary protein excretion was higher in patients with crescents (4.6 +/- 3.5 vs 1.2 +/- 0.9 g/day; P < 0.05). At the end of follow-up 17 patients (77.3%) from the crescent group and 3 (11.1%) from the non-crescent group had end-stage renal disease (P < 0.0001). The presence of crescents was associated with higher levels of initial serum creatinine and urinary protein excretion, and a higher frequency of hypertension and progression to end-stage renal disease.