Akiko Mii

Inhibition of matrix metalloproteinases reduces ischemia-reperfusion acute kidney injury.

Matrix metalloproteinases (MMPs) are endopeptidases that degrade extracellular matrix and involved in ischemic organ injuries. The present study was designed to determine the role of MMP-2 in the development of ischemic acute kidney injury (AKI). AKI was induced in MMP-2 wild-type (MMP-2+/+) mice by 30, 60, 90, and 120 min renal ischemia and reperfusion. Renal histology, expression and activity of MMP-2 and MMP-9, and renal function were examined during the development of AKI. AKI was also induced in MMP-2-deficient (MMP-2−/−) mice and MMP-2+/+ mice treated with inhibitor of MMPs (minocycline and synthetic peptide MMP inhibitor). In MMP-2+/+ mice, MMP-2 and MMP-9 activities increased significantly at 2 to 24 h, peaked at 6 h, after reperfusion. Immunohistochemical analysis identified MMP-2 in the interstitium around tubules and peritubular capillaries in the outer medulla. Acute tubular injury (ATI), including apoptosis and necrosis, was evident in the outer medulla at 24 h, along with renal dysfunction. As ischemia period increases, MMP-2 and MMP-9 activities at 6 h and severity of AKI at 24 h increased depending on the duration of ischemia between 30 and 120 min. However, the kidneys of MMP-2−/− mice showed minimal ATI; serum creatinine 24 h after reperfusion was significantly low in these mice. Inhibitors of MMPs reduced ATI and improved renal dysfunction at 24 h. We conclude that MMPs, especially MMP-2 have a pathogenic role in ischemia-reperfusion AKI, and that inhibitors of MMPs can protect against ischemic AKI.

ANG II receptor blockade enhances anti-inflammatory macrophages in anti-glomerular basement membrane glomerulonephritis

Macrophages are heterogeneous immune cell populations that include classically activated and alternatively activated (M2) macrophages. We examined the anti-inflammatory effect of ANG II type 1 receptor (AT(1)R) blocker (ARB) on glomerular inflammation in a rat model of anti-glomerular basement membrane (GBM) glomerulonephritis (GN). The study focused on infiltrating CD8(+) and CD4(+) cells and macrophages, as well as the heterogeneity of intraglomerular macrophages. Wistar-Kyoto rats were treated with high-dose olmesartan (3 mg.kg(-1).day(-1)), low-dose olmesartan (0.3 mg.kg(-1).day(-1)), or vehicle (control) 7 days before induction of anti-GBM GN. Control rats showed mainly CD8(+) cells and ED1(+) macrophages, with a few CD4(+) cells infiltrating the glomeruli. Necrotizing and crescentic glomerular lesions developed by day 7 with the increase of proteinuria. AT(1)R was expressed on CD8(+) and CD4(+) cells and on ED1(+) macrophages. Low-dose ARB had no anti-inflammatory effects in anti-GBM GN. However, high-dose ARB reduced glomerular infiltration of CD8(+) cells and ED1(+) macrophages and suppressed necrotizing and crescentic lesions by days 5 to 7 (P < 0.05). In addition, high-dose ARB reduced the numbers of ED3(+)-activated macrophages, suppressed glomerular TNF-alpha and IFN-gamma production, and downregulated M1-related chemokine and cytokines (monocyte chemoattractant protein type 1, IL-6, and IL-12). High-dose ARB also enhanced ED2(+) M2 macrophages by day 7 with upregulation of glomerular IL-4 and IL-13 and augmented CCL17, IL-1 receptor antagonist, and IL-10. We concluded that high-dose ARB inhibits glomerular inflammation by increasing the numbers of M2 macrophages and upregulation of anti-inflammatory cytokines and by suppressing M1 macrophage development with downregulation of M1-related proinflammatory cytokines.

Statin Attenuates Experimental Anti-Glomerular Basement Membrane Glomerulonephritis Together with the Augmentation of Alternatively Activated Macrophages

Macrophages are heterogeneous and include classically activated M1 and alternatively activated M2 macrophages, characterized by pro- and anti-inflammatory functions, respectively. Macrophages that express heme oxygenase-1 also exhibit anti-inflammatory effects. We assessed the anti-inflammatory effects of statin in experimental anti-glomerular basement membrane glomerulonephritis and in vitro, focusing on the macrophage heterogeneity. Rats were induced anti-glomerular basement membrane glomerulonephritis and treated with atorvastatin (20 mg/kg/day) or vehicle (control). Control rats showed infiltration of macrophages in the glomeruli at day 3 and developed crescentic glomerulonephritis by day 7, together with increased mRNA levels of the M1 macrophage-associated cytokines, interferon-gamma, tumor necrosis factor-alpha, and interleukin-12. In contrast, statin reduced the level of proteinuria, reduced infiltration of macrophages in glomeruli with suppression of monocyte chemotactic protein-1 expression, and inhibited the formation of necrotizing and crescentic lesions. The number of glomerular ED3-positive macrophages decreased with down-regulation of M1 macrophage-associated cytokines. Furthermore, statin augmented ED2-positive M2 macrophages with up-regulation of the M2 macrophage-associated chemokines and cytokines, chemokine (C-C motif) Iigand-17 and interleukin-10. Statin also increased the glomerular interleukin-10-expressing heme oxygenase-1-positive macrophages. Statin inhibited macrophage development, and suppressed ED3-positive macrophages, but augmented ED2-positive macrophages in M2-associated cytokine environment in vitro. We conclude that the anti-inflammatory effects of statin in glomerulonephritis are mediated through inhibition of macrophage infiltration as well as augmentation of anti-inflammatory macrophages.

Severe thiamine deficiency resulted in Wernicke's encephalopathy in a chronic dialysis patient

A 64-year-old male patient with diabetic nephropathy had been treated with maintenance hemodialysis therapy for 4 years, and had developed disturbed consciousness. The disturbance was firstly noticed by a primary care doctor who recognized slow responses in conversation. Prior to developing this symptom, the patient had noticed a loss of appetite for about 2 weeks. During a period of observation at an outpatient clinic, the symptoms became worse. He was admitted to a primary care hospital for 10 days, but his consciousness level deteriorated and he became unconscious (JCS 200). About 1 month after the onset of symptoms, the patient was transferred to our hospital. A brain computed tomography (CT) scan and magnetic resonance imaging (MRI) showed typical abnormal lesions in the aquaduct of the midbrain and thalamus, and a diagnosis of Wernickes encephalopathy was made. In addition, the patients serum thiamine level was extremely low (7 ng/ml). He received immediate treatment with intravenous thiamine administration (150 mg/day), and this significantly improved his symptoms (JCS 2). Dialysis patients may develop water-soluble vitamin deficiency as a result of the combination of reduced oral intake and increased loss of vitamins into the dialysate. Wernickes encephalopathy should be considered as one of many causes of disturbed consciousness in hemodialysis patients. A rapid diagnosis and adequate treatment are essential in order to minimize long-term neurological sequelae.

Renal thrombotic microangiopathy associated with chronic graft‐versus‐host disease after allogeneic hematopoietic stem cell transplantation

Thrombotic microangiopathy (TMA) is a major complication after hematopoietic stem cell transplantation (HSCT). In this study, we examined the clinical and pathologic features of 2 patients and 5 autopsy cases with HSCT‐associated renal TMA to clarify the association between graft‐versus‐host disease (GVHD) and renal TMA. The median interval between HSCT and renal biopsy or autopsy was 7 months (range 3–42 months). Clinically, acute and chronic GVHD occurred in 7 and 4 patients, respectively. Clinical evidence for TMA was detected in 2 patients, while chronic kidney disease developed in all patients. The main histopathological findings were diffuse endothelial injury in glomeruli, peritubular capillaries (PTCs), and small arteries. In addition, all cases showed glomerulitis, renal tubulitis, and peritubular capillaritis with infiltration of CD3+ T cells and TIA‐1+ cytotoxic cells, suggesting that GVHD occurred during the development of TMA. Diffuse and patchy C4d deposition was noted in glomerular capillaries and PTCs, respectively, in 2 biopsy and 2 autopsy cases, suggesting the involvement of antibody‐mediated renal endothelial injury in more than 50% of renal TMA cases. In conclusion, the kidney is a potential target of chronic GVHD that may induce the development of HSCT‐associated TMA. Importantly, some cases are associated with chronic humoral GVHD.

Focal segmental glomerulosclerosis after renal transplantation

Shimizu A, Higo S, Fujita E, Mii A, Kaneko T. Focal segmental glomerulosclerosis after renal transplantation.
Clin Transplant 2011: 25 (Suppl. 23): 6–14.
© 2011 John Wiley & Sons A/S.

Angiotensin II receptor blockade inhibits acute glomerular injuries with the alteration of receptor expression

Angiotensin II receptor blockade (ARB) suppresses the progression of chronic kidney disease. However, the renoprotective effect of ARB in the active phase of glomerulonephritis (GN) has not been evaluated in detail. We examined the alteration of angiotensin II receptors’ expression and the action of ARB on acute glomerular injuries in GN. Thy-1 GN was induced in rats that were divided into three groups (n=7, in each group); high dose (3 mg/kg/day) or low dose (0.3 mg/kg/day) olmesartan (Thy-1 GN+HD- or LD-ARB group), and vehicle (Thy-1 GN group). Renal function and histopathology were assessed by week 2. In the Thy-1 GN group, diffuse mesangiolysis and focal aneurysmal ballooning developed by day 3. Marked mesangial proliferation and activation progressed with glomerular epithelial injury. We confirmed that both angiotensin II type 1 receptor (AT1R) and type 2 receptor (AT2R) were expressed on glomerular endothelial, mesangial, epithelial cells, and macrophages, and increased 7 days after disease induction. However, ARB treatment caused a decrease in AT1R and a further increase in AT2R expression in glomeruli. ARB prevented capillary destruction and preserved eNOS expression after diffuse mesangiolysis. Mesangial proliferation and activation was suppressed markedly with low levels of PDGF-B expression. Glomerular desmin expression, which is a marker for injured glomerular epithelial cells, was diminished significantly with retained expression of nephrin and podoplanin. Glomerular macrophage infiltration was also inhibited. Proteinuria was suppressed significantly. Furthermore, these effects of ARB showed dose dependency. These results provide insights that ARB affects individual glomerular cells and macrophages through angiotensin II receptors, with the alteration of both AT1R and AT2R expressions, and leads to inhibition of the acute destructive and proliferative glomerular lesions in GN.

Renal thrombotic microangiopathy associated with chronic humoral graft versus host disease after hematopoietic stem cell transplantation

Thrombotic microangiopathy (TMA) is a known complication of hematopoietic stem cell transplantation (HSCT). The pathogenesis of TMA is controversial but considered to involve various factors such as total body irradiation, use of calcineurin inhibitors for prophylaxis against graft versus host disease (GVHD), viral infection, and GVHD. Herein we describe a case with renal TMA after HSCT, which was probably associated with antibody‐mediated endothelial cell injury from chronic GVHD (termed here ‘chronic humoral GVHD’). A 49‐year‐old man presented two years after HSCT with renal dysfunction and proteinuria but without the clinical features of TMA. Histopathological examination of renal biopsy showed chronic glomerular endothelial cell injury with double contour of the glomerular basement membrane, microthrombi and the deposition of complement split product C4d along the glomerular capillaries. Renal tubulitis and peritubular capillaritis were also noted with a multilayered basement membrane and patchy C4d deposition on peritubular capillaries. These findings resemble those of chronic antibody‐mediated rejection after kidney transplantation. Furthermore, C4d deposition suggests complement activation. Although circulating anti‐blood type and anti‐human leukocyte antigen antibodies were not detected, the renal TMA in this case was probably associated with chronic humoral GVHD.

Inhibition of capillary repair in proliferative glomerulonephritis results in persistent glomerular inflammation with glomerular sclerosis

The pathological process of glomerulonephritis (GN) includes glomerular capillary damage, and vascular endothelial growth factor (VEGF) has an important role in glomerular capillary repair in GN. We examined the effect of inhibition of glomerular capillary repair after capillary injury in GN. Experimental Thy-1 GN was induced in rats that were divided into two groups: rats that received anti-VEGF neutralizing antibody (50 μg per 100 g body weight per day) and those treated with the vehicle from day 2 to day 9. We assessed the renal function and histopathology serially until week 6. Rats of the Thy-1 GN group showed diffuse glomerular mesangiolysis with ballooning destruction of the capillary network by day 3. VEGF164 protein levels increased in the damaged glomeruli during days 5 to 10, and endothelial-cell proliferation increased with capillary repair in the vehicle-injected group. Proliferative GN resolved subsequently with decreased mesangial hypercellularity, and recovery of most of the glomeruli to the normal structure was evident by week 6. In contrast, administration of anti-VEGF antibody significantly decreased endothelial-cell proliferation and capillary repair in glomeruli by week 2. Thereafter, glomerular mesangial-cell proliferation and activation continued with persistent infiltration of macrophages. At week 6, segmental glomerular sclerosis developed with mesangial matrix accumulation and proteinuria. Deposition of type I collagen was also noted in sclerotic lesions. We conclude that impaired capillary repair was the underlying mechanism in the prolongation of glomerular inflammation in proliferative GN and in the development of glomerular sclerosis. Capillary repair has an important role in the recovery of glomerular damage and in the resolution of proliferative GN.

Proliferative glomerulonephritis with monoclonal immunoglobulin G3κ deposits in association with parvovirus B19 infection

Proliferative glomerulonephritis with monoclonal immunoglobulin G deposits is a recently described disease entity, characterized by nonorganized electron-dense deposits in glomeruli and immunofluorescence findings indicating monoclonal immunoglobulin G deposits. The pathogenesis of many cases of proliferative glomerulonephritis with monoclonal immunoglobulin G deposits remains unknown. We herein report 2 patients with parvovirus B19 infection who developed acute nephritic syndrome with hypocomplementemia (patient 1) or persistent proteinuria and congestive heart failure (patient 2); however, neither patient had detectable levels of serum monoclonal immunoglobulin G. Renal biopsy in both patients showed diffuse endocapillary proliferative glomerulonephritis with monoclonal immunoglobulin G3κ deposits, and electron microscopy showed nonorganized electron-dense deposits mainly in the subendothelial and mesangial areas. Clinical symptoms, abnormal laboratory findings, and urinary abnormalities recovered spontaneously in both cases within 4 weeks. Our 2 cases may be the first reported patients with proliferative glomerulonephritis with monoclonal immunoglobulin G deposits possibly associated with parvovirus B19 infection. Virus infection-associated immune disorders could be implicated in the pathogenesis of proliferative glomerulonephritis with monoclonal immunoglobulin G deposits.