Heterogeneous fibroblasts underlie age-dependent tertiary lymphoid tissues in the kidney

Acute kidney injury (AKI) is a common clinical condition defined as a rapid decline in kidney function. AKI is a global health burden, estimated to cause 2 million deaths annually worldwide. Unlike AKI in the young, which is reversible, AKI in the elderly often leads to end-stage renal disease, and the mechanism that prevents kidney repair in the elderly is unclear. Here we demonstrate that aged but not young mice developed multiple tertiary lymphoid tissues (TLTs) in the kidney after AKI. TLT size was associated with impaired renal function and increased expression of proinflammatory cytokines and homeostatic chemokines, indicating a possible contribution of TLTs to sustained inflammation after injury. Notably, resident fibroblasts from a single lineage diversified into p75 neurotrophin receptor(+) (p75NTR(+)) fibroblasts and homeostatic chemokine-producing fibroblasts inside TLTs, and retinoic acid-producing fibroblasts around TLTs. Deletion of CD4(+) cells as well as late administration of dexamethasone abolished TLTs and improved renal outcomes. Importantly, aged but not young human kidneys also formed TLTs that had cellular and molecular components similar to those of mouse TLTs. Therefore, the inhibition of TLT formation may offer a novel therapeutic strategy for AKI in the elderly.</p

The severity of glomerular endothelial cell injury is associated with infiltrating macrophage heterogeneity in endocapillary proliferative glomerulonephritis

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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 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