Apoptosis in the repair process of experimental proliferative glomerulonephritis

Apoptosis in the repair process of experimental proliferative glomerulonephritis. The recovery from the proliferative glomerulonephritis (GN) with reduction of hypercellularity is known in various experimental and human GN. To elucidate the participation of apoptosis in GN, we studied the experimental Thy-1.1 GN for six weeks. Apoptosis was recognized by both light and electron microscopy, and the biochemical expression of apoptosis was morphologically confirmed by in situ end-labeling method of fragmented DNA, using terminal deoxy-transferase. Mesangioproliferative GN was induced by a single administration of anti-Thy-1.1 monoclonal antibody in a rat. Mesangial cell proliferation started early in the process and the number of glomerular cells peaked from day 7 to day 10. Subsequently, the degree of proliferative lesion diminished with obvious reconstruction of the capillary structure, as well as decrease in the number of glomerular cells. During this period, proliferated mesangial cells returned to their original level of cellularity and apoptosis apparently increased in number among the glomeruli. Apoptosis was significantly noted from day 7 to week 4 and was in its maximum at day 10 to week 2. Following this period, by week 6 most of the glomeruli reverted to their original structure. The number of infiltrated neutrophils and macrophages in the glomeruli slowly decreased during the course of the disease, and a few apoptosis were also observed. It is concluded that proliferated glomerular cells regress by apoptosis in the repairing process of GN. Apoptosis plays an essential role in the recovery to the original glomerular structure in GN

Glomerular endothelial cell injury and focal segmental glomerulosclerosis lesion in idiopathic membranous nephropathy.

Focal segmental glomerulosclerosis (FSGS) lesions have often been discussed as a negative predictor in idopathic membranous nephropathy (MN). The mechanism of the development of FSGS lesion in MN is still uncertain.From 250 cases of MN, 26 cases contained FSGS lesion. We compared the clinicopathological characteristics between MN cases with FSGS lesion [MN-FSGS(+)] and MN without FSGS lesion [MN-FSGS(-)], matched for gender, age, stage of MN.The glomerular filtration rate (eGFR) was significantly lower in MN-FSGS(+) cases compared to MN-FSGS(-), although nephrotic syndrome, hematuria, and systolic blood pressure levels were not significantly different between the two groups. Pathologically, glomeruli in MN-FSGS(+) cases showed narrowing and loss of glomerular capillaries with separating from GBM or disappearance of CD34+ endothelial cells, and accumulation of extracellular matrix (ECM) in capillary walls, indicating the development of glomerular capillary injury. These findings of endothelial injury were seen even in MN-FSGS(-) cases, but they were more prominent in MN-FSGS(+) than MN-FSGS(-) by computer assessed morphometric analysis. In MN-FSGS(+) cases, 44 out of 534 glomeruli (8.2%) contained FSGS lesions (n = 31, NOS lesion; n = 13, perihilar lesion). Significant thickness of GBM with ECM accumulation was evident in MN-FSGS(+) cases. Podocyte injury with effacement of foot processes was also noted, but the expression of VEGF on podocytes was not different between the two groups, which suggests that the significant thickness of capillary walls may influence the function of VEGF from podocyte resulting in the glomerular capillary injury that contribute to the development of FSGS lesion in MN.Glomerular capillary injury was seen in all MN cases. Furthermore, the prominent injuries of glomerular capillaries may be associated with the deterioration of eGFR and the formation of FSGS lesions in MN

Acute graft-versus-host disease of the kidney in allogeneic rat bone marrow transplantation.

Allogeneic hematopoietic cell or bone marrow transplantation (BMT) causes graft-versus-host-disease (GVHD). However, the involvement of the kidney in acute GVHD is not well-understood. Acute GVHD was induced in Lewis rats (RT1l) by transplantation of Dark Agouti (DA) rat (RT1(a)) bone marrow cells (6.0 × 10(7) cells) without immunosuppression after lethal irradiation (10 Gy). We examined the impact of acute GVHD on the kidney in allogeneic BMT rats and compared them with those in Lewis-to-Lewis syngeneic BMT control and non-BMT control rats. In syngeneic BMT and non-BMT control rats, acute GVHD did not develop by day 28. In allogeneic BMT rats, severe acute GVHD developed at 21-28 days after BMT in the skin, intestine, and liver with decreased body weight (>20%), skin rush, diarrhea, and liver dysfunction. In the kidney, infiltration of donor-type leukocytes was by day 28. Mild inflammation characterized by infiltration of CD3(+) T-cells, including CD8(+) T-cells and CD4(+) T-cells, and CD68(+) macrophages to the interstitium around the small arteries was noted. During moderate to severe inflammation, these infiltrating cells expanded into the peritubular interstitium with peritubular capillaritis, tubulitis, acute glomerulitis, and endarteritis. Renal dysfunction also developed, and the serum blood urea nitrogen (33.9 ± 4.7 mg/dL) and urinary N-acetyl-β-D-glucosaminidase (NAG: 31.5 ± 15.5 U/L) levels increased. No immunoglobulin and complement deposition was detected in the kidney. In conclusion, the kidney was a primary target organ of acute GVHD after BMT. Acute GVHD of the kidney was characterized by increased levels of urinary NAG and cell-mediated injury to the renal microvasculature and renal tubules

The injury of the glomerular endothelial cells and podocytes in idiopathic membranous nephropathy (MN).

<p>(A) In MN-FSGS(+) cases, an increase in the number of endothelial cells, swelling of the nuclei and cytoplasm, loss of fenestra, and widening of the subendothelial space were noted, suggesting the development of glomerular endothelial cell injury. (B) Narrowing of the capillary lumen was seen with foot process effacement of podocytes, widening of subendothelial space, and mesangial interposition, suggesting the presence of podocyte injury and the findings of reaction of glomerular endothelial cell injury. (C) Infiltration of monocytes and macrophages was noted in glomerular capillary lumens and subendothelial spaces with swelling of the nuclei and cytoplasm and loss of fenestra in glomerular endothelial cells, suggesting the glomerular endothelial cell injury and macrophage infiltration. (D) In MN-FSGS(−) cases, segmental glomerular endothelial cell damage was detected with infiltration of monocyte and macrophages, thickening of glomerular capillary walls, and loss of foot processes of podocytes, suggesting that, although the severity was mild, injuries of glomerular endothelial cells and podocytes were developed in glomeruli even in MN-FSGS(−) cases.</p

Box and Whisker plot of the glomerular tuft area (enlarged glomeruli) (A), the number of glomerular capillaries (B), the glomerular capillary area (C), and the glomerular ECM area (D) in cases of minor glomerular abnormalities (control), MN cases with FSGS lesion (FSGS +) and without FSGS lesion (FSGS −).

<p>(A) The enlargement of glomerular tuft area (glomerular hypertrophy) was evident in both MN cases with and without FSGS lesion compared to control. However, there was no significantly difference in glomerular tuft area in MN cases with and without FSGS lesion. (B) The decreased number of glomerular capillaries was noted in MN-FSGS(+) compared to control and MN-FSGS(−), suggesting the prominent loss and reduced glomerular capillaries in MN-FSGS(+). (C) The reduced area of glomerular capillaries was noted in MN-FSGS(+) cases compared to control and MN-FSGS(−), indicating the narrowing of glomerular capillaries in MN-FSGS(+). There was no significant difference in glomerular capillary area in control and MN-FSGS(−) cases. (D) The increase of glomerular ECM area was observed in MN with or without FSGS lesion compared to control, suggesting the development of enlarged glomeruli and the narrowing glomerular capillaries with ECM accumulation in MN cases.</p

Several glomerular capillary alterations in cases of idiopathic membranous nephropathy without FSGS lesion (CD34 stain, x600).

<p>In the glomeruli with minimal glomerular abnormalities by light microscopy (A), nearly normal glomerular capillary network was identified without ECM accumulation. During the development of capillary narrowing in small glomerular area (B), segmental glomerular area (C), and global glomerular area (D and E), ECM accumulated in mesangium and capillary walls in glomeruli. In global sclerotic glomeruli (F), marked and complete loss of glomerular capillaries was noted with massive accumulation of ECM in glomeruli.</p

Several histological parameters in MN cases with or without FSGS lesion.

<p>* Student’s t-test</p><p>** Mann-Whitney U test</p><p>Staining intensity of VEGF based on immunohistochemical study was scored semiquantitatively (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116700#sec006" target="_blank">Materials and Methods</a>).</p><p>Interstitial fibrosis and arteriosclerosis were also graded semiquantitatively (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116700#sec006" target="_blank">Materials and Methods</a>).</p><p>Several histological parameters in MN cases with or without FSGS lesion.</p

The relationship between the areas of glomerular capillaries and glomerular ECM in glomerular cross section in idiopathic membranous nephropathy (MN) by computer-assessed morphometric analysis.

<p>(A) The areas (μm²) of glomerular capillaries (X-axis) and ECM (Y-axis) were measured in MN-FSGS(+) cases (blue rhombus), MN-FSGS(−) cases (red square), and minor glomerular abnormalities in control (yellow x). In MN cases with or without FSGS lesion, increase of glomerular capillary area and/or glomerular ECM area was evident, suggesting the development of glomerular hypertrophy. In MN-FSGS(−) cases, the area of capillaries was positively correlated with the area of ECM in glomeruli. In contrast, there was no correlation between the areas of capillaries and ECM in glomeruli in MN-FSGS(+), suggesting the development of decrease of glomerular capillary area with increase of ECM area in enlarged glomeruli. (B) To avoid the effects of the variation in the size of glomeruli, the areas of glomerular capillaries and ECM in glomeruli were adjusted by using the area of glomerular capillaries / the area of glomerular tuft, and the area of glomerular ECM / the area of glomerular tuft. Regardless of the presence or absence of FSGS lesion, the areas of glomerular capillaries and ECM were negatively correlated, indicating that the narrowing and decrease of glomerular capillaries was associated with the accumulation of ECM. (C, D) We examined the areas of glomerular capillaries and ECM in glomeruli in each stage of MN (stage I to IV) in cases without FSGS lesion (C, FSGS −) and with FSGS lesion (D, FSGS +). The horizontal boundary is set at the average of glomerular capillary area of all glomeruli in control and MN cases with and without FSGS lesion. The longitudinal boundary is set at the average of glomerular ECM area of all glomeruli in control and MN cases with and without FSGS lesion. In accordance with the setting the boundary for the average of the areas of glomerular capillaries and glomerular ECM, all glomeruli were divided into 4 categories; a: large capillary area with minimal accumulation of ECM, b: large capillary area with marked accumulation of ECM, c: decrease of glomerular capillary area with minimal accumulation of ECM, and d: decrease of glomerular capillary area with marked accumulation of ECM. (n = number) is the number of cases of MN with and without FSGS lesion in each category. In MN-FSGS(−) cases (C), many cases, especially stage I and stage II, were present in category a (36/86: 41.9%). In contrast, the most common category in MN-FSGS(+) cases (D), was d (57/95: 60.0%), and many cases of stage III (18/24: 75.0%) and IV (11/17:64.7%) fell into this category. These findings indicate that the decrease of glomerular capillaries with increase of glomerular ECM area was more prominent in MN-FSGS(+) than those in MN-FSGS(−) cases.</p

The areas of glomerular capillaries and glomerular ECM in computer-assessed morphometric analysis.

<p>The area of glomerular tuft (dotted line in A and D), the area and number of glomerular capillaries (green areas in B and E), and the area of glomerular ECM (green areas in C and F) in each glomerulus were assessed by computer-assisted image analyzer. In the nearly normal glomeruli in light microscopic findings (A-C), large glomerular capillary area was noted with minimal ECM accumulation. In contrast, the area of glomerular capillaries decreased with narrowing glomerular capillaries and the accumulation of glomerular ECM in glomerulus in the development of glomerular sclerosis (D-F).</p