Mechanism of hematuria: I. Electron microscopic demonstration of the passage of a red blood cell through a glomerular capillary wall in rat masugi nephritis

Ultrastructural Characterization of the Glomerulopathy in Alport Mice by Helium Ion Scanning Microscopy (HIM)

The glomerulus exercises its filtration barrier function by establishing a complex filtration apparatus consisting of podocyte foot processes, glomerular basement membrane and endothelial cells. Disruption of any component of the glomerular filtration barrier leads to glomerular dysfunction, frequently manifested as proteinuria. Ultrastructural studies of the glomerulus by transmission electron microscopy (TEM) and conventional scanning electron microscopy (SEM) have been routinely used to identify and classify various glomerular diseases. Here we report the application of newly developed helium ion scanning microscopy (HIM) to examine the glomerulopathy in a Col4a3 mutant/Alport syndrome mouse model. Our study revealed unprecedented details of glomerular abnormalities in Col4a3 mutants including distorted podocyte cell bodies and disorganized primary processes. Strikingly, we observed abundant filamentous microprojections arising from podocyte cell bodies and processes, and presence of unique bridging processes that connect the primary processes and foot processes in Alport mice. Furthermore, we detected an altered glomerular endothelium with disrupted sub-endothelial integrity. More importantly, we were able to clearly visualize the complex, three-dimensional podocyte and endothelial interface by HIM. Our study demonstrates that HIM provides nanometer resolution to uncover and rediscover critical ultrastructural characteristics of the glomerulopathy in Col4a3 mutant mice.

Urinary sediment suggests lupus nephritis histology

Objectives

The objective of this paper was to evaluate correlations between kidney biopsy indexes (activity and chronicity) and urinary sediment findings; the secondary objective was to find which components of urinary sediment can discriminate proliferative from other classes of lupus nephritis.

Methods

Lupus nephritis patients scheduled for a kidney biopsy were included in our study. The morning before the kidney biopsy, we took urine samples from each patient. Receiver operating characteristic (ROC) curves were plotted to determine the area under the curve (AUC) of each test for detecting proliferative lupus nephritis; a classification tree was calculated to select a set of values that best-predicted lupus nephritis classes.

Results

We included 51 patients, 36 of whom were women (70.6%). Correlations of lupus nephritis activity index with the counts in the urinary sediment of erythrocytes (isomorphic and dysmorphic), acanthocytes, and leukocytes were 0.65 ( p < 0.0001) 0.62 ( p < 0.0001) and 0.22 ( p = 0.1228), respectively. Correlations of lupus nephritis chronicity index with the counts of erythrocytes, acanthocytes, and leukocytes were 0.60 ( p ≤ 0.0001), 0.52 ( p = 0.0001) and 0.17 ( p = 0.2300), respectively. Our classification tree had an accuracy of 84.3%.

Conclusions

Evaluation of urine sediment reflects lupus nephritis histology.

[Extracorporeal shock-wave lithotripsy induced ultrastructural changes to the renal parenchyma under aspirin use. Electron microscopic findings in the rat kidney]

BACKGROUND

The risk of hemorrhagic complications after extracorporeal shock-wave lithotripsy (ESWL) increases in patients with aspirin intake, but the hematoma-inducing mechanism has not been understood completely at the ultrastructural level.

METHODS

The effect off shock-waves on the kidneys of male Wistar-rats (n=24) was investigated in an experimental setting using a special ESWL device. Ultrastructural examination was performed by light-, transmission electron- and scanning electron microscopy.

RESULTS

Shock-wave induced tissue damage appeared in all kidneys independently of aspirin intake. Endothelial detachment, lethal cell injury, gaps and mechanical disruption of the glomerular basement membrane were regularly found. After 1 week, repair processes were completed with evidence of permanent fibrosis in some cases.

CONCLUSIONS

ESWL can induce modest as well as fatal damage to renal tissue cells. Therefore, after an ESWL-induced hematoma a second ESWL should not be performed within 1 week of the first treatment.

Glomerular extracellular matrices in rat diabetic glomerulopathy by scanning electron microscopy

Characteristic pathological changes in the glomeruli in diabetic nephropathy include expansion of the mesangial matrix and thickening of the glomerular basement membrane (GBM). Using an acellular digestion technique combined with scanning electron microscopy, the three-dimensional ultrastructural changes in glomerular extracellular matrices were studied in rats with diabetic glomerulopathy. Diabetes was induced by the intravenous injection of streptozotocin and morphological analyses were performed 3, 6 and 11 months after the injection. Expansion of mesangial area and GBM thickening became evident with time. After treatment with the series of detergents, all cellular components were completely removed leaving the extracellular matrices intact. In normal controls, the mesangial matrix appeared as fenestrated septa with oval or round stomata between the glomerular capillaries. In diabetic glomerulopathy, expansion of mesangial matrix and narrowing of the mesangial fenestrae were observed. These changes in the mesangial matrices seem to play a vital role in the progression of glomerulosclerosis in rat diabetes. A subendothelial thin layer of the GBM was continuous with the mesangial matrix. One cause of GBM thickening in streptozotocin diabetes may be expansion of the mesangial matrix into the peripheral GBM.

Three-dimensional architecture of glomerular extracellular matrices in diabetic glomerulosclerosis

The three-dimensional ultrastructural changes of the glomerular extracellular matrices in diabetic glomerulosclerosis were studied in acellular rat and human diabetic glomeruli by scanning electron microscopy. The mesangial matrix appeared as fenestrated septa with oval stomata between the glomerular capillaries in normal control specimens. In diabetic glomerulosclerosis, both in humans and rats, expansion of mesangial matrix and narrowing of the mesangial fenestrae were observed. A thin layer of the mesangial matrix extended into the peripheral glomerular basement membrane (GBM) subendothelially. Thickening of the GBM in diabetic nephropathy might be due to expansion of the mesangial matrix into the peripheral GBM.

Hematuria of tubular origin

Hematuria (HU) of tubular origin is described on the basis of ultrastructural investigations of two rejected human renal allografts. The red blood cells (RBC) got into the interstitium through the walls of the damaged intertubular capillaries, and, via ruptures of the tubular basement membrane (BM), they may pass from the interstitium into the tubular lumen, causing HU. Rupture of the tubular BM may develop owing to the enzymes released by interstitial inflammatory cells or to the difference in the interstitial and intratubular pressures. Some of the RBC already in the tubular lumen may penetrate between the epithelial cells and even between the epithelium and the BM, probably because of the locally increased intraluminal pressure. If the RBC reach the BM, the epithelial cells produce a new, thin BM above them, with disintegration of the outer older one, and, thus, the RBC may pass into the interstitium again. This phenomenon is called the tubulointerstitialis circulation of RBC.