A quantitative study of glomerular basement membrane changes in IgA nephropathy

A quantitative study of glomerular basement membrane (GBM) changes in 16 cases of IgA nephropathy was carried out on two whole glomeruli per case using a wide-field electron microscope. We found that GBM changes are observed more frequently than previously reported, although some changes are small and uneven in distribution. Changes include (a) attenuation, (b) lytic attenuation, (c) garland-shaped widening of the GBM, (d) dome-shaped widening of the GBM, and (e) disruption of the GBM. There was some correlation between the severity of light microscopic findings and the percentage of GBM affected by complicated changes ((b)-(e)). The percentage of complicated GBM changes correlated with the amount of proteinuria at biopsy. The frequent occurrence of GBM changes in IgA nephropathy suggests that they might be playing a role in the pathogenesis of IgA nephropathy.     

Immunoelectron microscopic study of childhood IgA nephropathy and Henoch-Schönlein nephritis

Summary Renal biopsy specimens from 11 children with Henoch-Schönlein nephritis and 14 with IgA nephropathy were examined by immunoelectron microscopy. The distribution of IgA reaction product (RP) was found to be similar to that of the electron-dense deposits seen with conventional electron microscopy. Deposits of IgA-RP were present in the mesangium and in the subendothelial region of the peripheral glomerular capillary wall in all patients. Subepithelial deposits of IgA-RP were seen in 12 patients. Deposits of IgG-RP were rare and no deposits of IgM-RP were observed. Deposits of C3-RP were found frequently, although they were smaller and less extensive than deposits of IgA-RP. There was no significant difference between Henoch-Schönlein nephritis and IgA nephropathy with regard to immunoelectron microscopy findings. These observations suggest that Henoch-Schönlein nephritis and IgA nephropathy are both forms of mesangiopathic glomerulonephritis caused by immune complexes, mainly composed of IgA.     

Localization of glomerular 'deposits' in Henoch-Schönlein nephritis

Twenty-five renal biopsies from patients with Henoch-Schönlein nephritis were examined using light microscopy, immunofluorescence, I μm plastic-embedded sections and electron microscopy. The I μm plastic-embedded sections and electron microscopy showed deposits in mesangial, subendothelial and subepithelial sites. Some of the latter were very large and similar to those which have been described as 'humps' in acute proliferative glomerulonephritis. Immunofluorescence showed the mesangial deposition of IgG, IgA and C₃ with extension into a peripheral position in some cases. Fibrin was frequently found associated with crescents. The case for Henoch-Schönlein disease being mediated, in part at least, by immune complex deposition, is presented.     

IgA1在儿童IgA肾病及紫癜性肾炎发病中的作用研究进展

IgA肾病和紫癜性肾炎在免疫荧光下均表现为以IgA为主的免疫复合物在肾小球系膜区的广泛沉积,近年来对这两种疾病发病机制的研究取得了很大进展,许多研究已证明异常糖基化的IgA1易于在系膜区沉积,并通过免疫应答反应对系膜细胞和足细胞造成损伤.对异常糖基化IgA1的深入研究将进一步揭示儿童IgA肾病及紫癜性肾炎的发病机制,为疾病的治疗提供新思路.     

Lymph node pathology in Henoch-Schönlein purpura

This report describes two cases of Henoch-Schönlein purpura with unusual lymph node pathology. The patients presented with severe colicky abdominal pain mimicking acute appendicitis but a normal appendix was removed in each case. Enlarged mesenteric lymph nodes were removed, with a clinical suspicion of Yersinia infection. Cultures and serology were negative. Histological examination of the lymph nodes revealed follicular granulomas, follicular microabscesses and leucocytoclastic vasculitis. Immunohistochemical studies revealed deposition of IgA, IgG and C₃ in the vessel walls, the finding of IgA supporting a diagnosis of Henoch-Schönlein purpura.     

The thin glomerular basement membrane in children with haematuria

To determine the specificity and significance of widespread attenuation of the glomerular basement membrane on electron microscopy, 240 renal biopsies from 218 children were studied retrospectively. Twenty-three patients showed diffuse attenuation and three of them are cases of hereditary nephritis. The other 20 patients are characterized by persistent microscopic haematuria, absence of proteinuria, normal blood pressure and renal function, and minimal glomerular changes. In 10 of these 20 children, microscopic haematuria was also present in the family. We conclude that widespread attenuation of the glomerular basement membrane is a characteristic of benign familial and non-familial haematuria. The thin glomerular basement membrane may be responsible for the haematuria and may result from incomplete glomerular maturation.     

Clinico-pathological association of Henoch-Schoenlein purpura nephritis and IgA nephropathy in children

Objective: Henoch-Schonlein purpura nephritis (HSPN) and IgA nephropathy (IgAN) are similar syndromes. We aimed to determine whether the crescent formation/immunocomplex in glomeruli is associated with the differences of the biochemical indexes between HSPN and IgAN. Methods: We investigated the medical records of 137 HSPN cases and 41 IgAN cases from January 2009 to April 2014 in Nanjing Children’s Hospital of Nanjing Medical University. The clinical and pathological data were analyzed and compared between HSPN and IgAN. Results: HSPN patients had markedly higher levels of blood white blood cell (WBC), hemoglobulin (Hb) and platelet (PLT), lower levels of hematuria, blood nitrogen (BUN) and C4 compared with IgAN cases. Crescents formation and C3 deposition in the kidney did not affect these differences. Significantly lower levels of hematuria, blood IgG, IgM and C4 in HSPN compared with IgAN cases were observed among patients with IgG deposition. Markedly higher levels of WBC and Hb, lower levels of hematuria, creatinine (Cr), C4 in HSPN compared with IgAN cases were observed among patients with IgM deposition. No marked differences of the biochemical indexes were noted between HSPN and IgAN cases among patients with C1q deposition. Markedly higher levels of WBC and Hb, lower level of blood C4 in HSPN compared with IgAN cases were observed among patients with fibrogen deposition. Conclusions: The different levels of biochemical indexes at presentation between HSPN and IgAN may be associated with the deposition of IgG, IgM, C1q and fibrogen in the kidney.     

Quantitive changes in the glomerular basement membrane components in human membranous nephropathy

In membranous nephropathy (MN), the glomerular basement membrane (GBM) is thickened due to accumulation of GBM material between and around the subepithelial immune deposits. Alterations in the GBM components in relation to subepithelial deposits and GBM thickening are not clearly defined. The GBM distribution of classical and novel [α4(IV)] chains of type IV collagen, laminin, and fibronectin have been studied in seven patients with MN and in three normal controls by a quantitative immunogold technique. In normal kidneys, the labelling of type IV collagen or fibronectin was distributed predominantly along the endothelial side of the GBM; α4(IV) was found in the lamina densa; and laminin was concentrated in the epithelial zone of the GBM (P<0·01). In MN, there were increased immunogold densities for classical and novel type IV collagen chains, laminin, and fibronectin in the spikes of MN patients compared with controls (P<0·05). Furthermore, gold particle labelling for the α4(IV) collagen chain was increased in the middle zone (P<0·01) and that for fibronectin was increased in the endothelial and middle zones of the GBM (P<0·05) compared with normal controls. These findings suggest that subepithelial immune deposits stimulate glomerular epithelial cells (GEC), resulting in enhanced secretion of classical and novel type IV collagen chains, laminin, and fibronectin, forming spikes in MN; of these newly formed components, only novel type IV collagen appears to migrate towards the middle zone of the GBM, contributing to thickening of this zone. The results also suggest that fibronectin, possibly derived from the circulation, is related to thickening of the endothelial zone of the GBM, which in turn might be related to progressive glomerulosclerosis. © 1997 by John Wiley & Sons, Ltd.     

小儿肾小球薄基膜病的临床病理研究

目的 :探讨小儿肾小球薄基膜病 (TBMN)的临床病理特征。方法 :对 11例TBMN患儿进行了临床、病理及超微结构的系统观察 ,测量了肾小球基膜 (GBM)及致密层的厚度 ,对小儿薄基膜病的临床病理特征进行了分析。结果 :11例小儿TBMN临床主要表现为单纯血尿 ,无其它明显的阳性体征 ,光镜下肾小球无明显改变或轻微异常 ,未见蛋白管型 ,包曼囊内及肾小管腔内可见渗出的红细胞 ,电镜下GBM广泛变薄 ,平均厚度 <2 0 0nm ,致密层厚度 <10 0nm。结论 :小儿肾小球薄基膜病的诊断主要依靠电镜 ,同时必须强调与临床病史、生化检查及病理组织学、免疫组化紧密结合方可确诊。     

Clinicopathologic comparisons of IgA nephropathy and IgA vasculitis nephropathy in children: a ten-year single-center experience

Background/aim To investigate the similarities and differences of renal clinical and renal pathology between IgA nephropathy (IgAN) and IgA vasculitis nephritis (IgAVN) in children. Materials and methodsA total of 237 children with IgAN and 190 children with IgAVN were included. The general conditions, clinical characteristics, final diagnosis, clinical and pathological classification of the children were intercepted at the time of admission, and the retrospective comparative analysis was carried out. ResultsThe results showed that the median course of disease in IgAN group was longer than that in IgAVN group (p = 0.02). Patients with IgAN had a significantly higher duration of infection than the patients with IgAVN (p = 0.03). The white blood cell count (WBC), hemoglobin (HGB) in IgAN group were significantly lower than that in IgAVN group (p = 0.02). The serum creatinine in IgAN group was higher than that in IgAVN group (p = 0.02). Patients with IgAN and IgAVN had statistically significant differences in pathological typing between clinical types: hematuria and proteinuria, nephrotic syndrome and chronic nephritis (p = 0.004). ConclusionThe clinical manifestations of IgAN and IgAVN were similar, but the onset of IgAN was hidden and the clinical manifestations were relatively serious. Renal pathology was mainly glomerulosclerosis and renal tubular atrophy. IgAVN was characterized by acute onset and good renal function. Renal pathology was dominated by endothelial hyperplasia and crescent formation. These differences did not support the hypothesis that the two diseases are the same.     

Ultrastructural localization of anionic and cationic ferritin in the rat glomerular basement membrane in protein-overload proteinuria

The penetration into the glomerular basement membrane of anionic and cationic ferritin has been studied in rats made proteinuric by intraperitoneal administration of bovine serum albumin. In comparison with control animals anionic ferritin penetrated the glomerular basement membrane to a much greater extent in proteinuric rats. Some ferritin particles were observed in small invaginations of the epithelial cell membrane adjacent to the glomerular basement membrane and incorporated in pinocytotic vesicles within the epithelial cell cytoplasm. This was not seen in control animals. Cationic ferritin distribution in the glomerular basement membrane was similar in control and proteinuric rats suggesting that the increased anionic ferritin penetration observed occurs without any reduction in fixed anionic charge.     

Immunoelectron microscopic studies of immune complex deposits and basement membrane components in IgA nephropathy

The relationship between the immune complex deposits of mesangial IgA nephropathy and the basement membrane components, type IV collagen and fibronectin, has been investigated by an indirect immunogold technique in four cases of mesangial IgA disease. Using paraformaldehyde-fixed, Lowicryl K4M resin-embedded kidney, IgA, IgM and C3 were localized in the mesangial electron-dense deposits with 10 and 20 nm gold-labelled secondary antibodies. In the same glomeruli, type IV collagen and fibronectin were rarely present within the electron-dense deposits, although both were distributed throughout the remainder of the mesangial matrix with the exception of the subepithelial regions. These two components were also present within the glomerular basement membrane and localized mainly on the endothelial aspect. A similar distribution of the basement membrane components was seen in a control kidney processed in the same way. This technique gives reproducible results and has demonstrated for the first time the relationship between the mesangial immune complex deposits of mesangial IgA nephropathy and the basement membrane components of the matrix in which they are found.     

Isolation and characterization of the tubular basement membrane antigen associated with human tubulo-interstitial nephritis.

The target antigen, a 54-kD glycoprotein (gp54), reactive with sera from patients with anti-tubular basement membrane (anti-TBM) nephritis, was isolated from collagenase-digested (CD) bovine TBM. The purified gp54 was shown to be non-collagenous by amino acid analysis, and to be a unique basement membrane component by amino-terminal sequencing. The nephritogenicity of gp54 was demonstrated by immunizing strain XIII guineapigs with purified gp54, and producing anti-gp54 antibody and tubulo-interstitial nephritis. Anti-gp54 antibody, affinity-purified from sera of patients with anti-TBM nephritis, bound by immunoblotting to 54-kD and, to a lesser extent, 48-kD components of partially purified human CD-TBM. Indirect immunofluorescence showed that gp54 was present in the basement membrane of proximal tubules of the kidneys of normal human, cow, rabbit, guineapig and Brown-Norway rat but not in Lewis rat. Immunoelectron microscopy revealed localization of gp54 along the interstitial side of the TBM and its association with interstitial collagen fibres. These results indicate that gp54 is the nephritogenic antigen involved in tubulo-interstitial nephritis, and is unique in chemical characteristics and localization in the kidney.     

New rat model induced by anti-glomerular basement membrane antibody shows severe glomerular adhesion in early stage and quickly progresses to end-stage renal failure

The aim of the present study was to introduce a new anti-glomerular basement membrane nephritis model in which plasma creatinine levels dramatically increased only 4 weeks after a single administration of rabbit antirat glomerular basement membrane antibody in Sprague–Dawley rats. According to renal morphology, glomerular lesions characterized by mesangial expansion and adhesion of the glomerular tuft to Bowman's capsule were observed in the early stage at day 7 after disease induction; adhesion was detected in approximately 90% of glomeruli 14 days after antibody injection. After 21 days the rats exhibited pronounced glomerulosclerosis/hyalinosis and severe tubulointerstitial lesions characterized by interstitial fibrosis. Urinary podocytes excreted in nephritis rats were studied and it was found that urinary podocyte loss might be closely related to progression of renal injury. Because this new model simply and reproducibly demonstrates development of end-stage renal disease, it will be beneficial for elucidating mechanisms by which chronic renal injury irreversibly progresses, as well as for developing therapeutic agents for chronic renal failure.     

Imbalances in serum proinflammatory cytokines and their soluble receptors: a putative role in the progression of idiopathic IgA nephropathy (IgAN) and Henoch–Schönlein purpura nephritis,and a potential target of immunoglobulin therapy?

Following recent experimental data suggesting an aggravating effect of circulating proinflammatory cytokines on the histological lesions of IgAN, we studied changes in serum proinflammatory cytokines and their soluble receptors and antagonists in patients treated with polyvalent immunoglobulins (15 with severe nephropathy who had indicators of poor prognosis: heavy proteinuria, hypertension, altered renal function and Lee's histological grade III or IV; and 14 with moderate forms of IgAN who had permanent albuminuria > 300 mg/day and < 2000 mg/day, Lee's histological grade II and a glomerular filtration rate > 70 ml/min) in comparison with healthy controls (n = 20) and patients with non-IgA nephritides (n = 50). These were measured by means of specific immunometric assays before and after 9 months of immunoglobulin therapy. Total tumour necrosis factor (TNF) serum and IL-6 levels were elevated in IgAN patients before therapy, relative to controls, and normalized after immunoglobulin therapy. Levels of soluble TNF receptor of type I (sR55) and type II (sR75) increased on immunoglobulin therapy. TNF index α-55,75 used to assess biologically available TNF-α (ratio of total TNF-α divided by levels of soluble TNF receptors sR55 and sR75) was elevated before therapy and was below healthy control values after 9 months of immunoglobulin administration. Levels of serum IL-1 receptor antagonist were low prior to immunoglobulin administration in patients with severe forms of IgAN, and normalized on therapy. Serum interferon-gamma was unmodified. The histological activity index correlated with serum total TNF-α, TNF index α-55,75 and serum IL-6 levels, whereas proteinuria correlated with serum total TNF-α and TNF index α-55,75 but not with serum IL-6. These data suggest that the overproduction of proinflammatory cytokine is unbalanced by their natural antagonists in IgAN and Henoch–Schönlein syndrome. This process may play a role in the progression of the disease and be one of the targets of immunoglobulin therapy.     

The evolution of crescentic nephritis and alveolar haemorrhage following induction of autoimmunity to glomerular basement membrane in an experimental model of Goodpasture's disease

Goodpasture's, or anti-glomerular basement membrane (GBM), disease presents with rapidly progressive glomerulonephritis and lung haemorrhage, and is caused by autoimmunity to the NC1 domain of the alpha3 chain of type IV collagen (alpha3(IV)NC1). This study examines the development of crescentic nephritis and alveolar haemorrhage in a model of Goodpasture's disease, experimental autoimmune glomerulonephritis (EAG), induced in WKY rats by immunization with rat GBM in adjuvant. An increase in circulating anti-GBM antibodies and albuminuria was observed by week 2, which increased further by weeks 3 and 4, while a decrease in creatinine clearance was observed by week 2, which decreased further by weeks 3 and 4. The kidneys of animals with EAG showed linear deposits of IgG on the GBM and a transient glomerular infiltration by CD4+ T cells at week 2. By week 3 there were large deposits of fibrin in Bowman's space, and glomerular infiltration by CD8+ T cells and macrophages, accompanied by focal necrotizing glomerulonephritis with crescent formation. Ultrastructural studies showed glomerular endothelial cell swelling and epithelial cell foot process effacement at week 2. As the lesion progressed, capillary loops became occluded and the mesangium became expanded by mononuclear cells. By week 3 there was detachment of the endothelium from the GBM, and accumulation of fibrin beneath the disrupted endothelial cells and in Bowman's space. Occasional breaks were observed in the continuity of the basement membrane, and cytoplasmic projections from infiltrating mononuclear cells could be seen crossing the capillary wall between the lumen and the crescent. The lungs of animals with EAG showed patchy binding of IgG to the alveolar basement membrane (ABM) at week 2, and infiltration of the interstitium by CD8+ T cells and macrophages by weeks 3 and 4, accompanied by both interstitial and alveolar haemorrhage. Ultrastructural studies showed focal mononuclear cell infiltrates in alveolar walls at week 2. Occasional breaks were observed in the basement membrane and adjacent endothelium by weeks 3 and 4, together with accumulation of surfactant and erythrocytes within the alveolar spaces. This study defines for the first time the relationship between the immunological and pathological events during the evolution of EAG, and provides the basis for further work on the pathogenesis of Goodpasture's disease.     

Segmental glomerular necrosis as an active index of IgA nephropathy: A study with 100 serial sections of 128 cases

One hundred serial sections from each of 128 cases with immunoglobulin A (IgA) nephropathy were examined by light microscopy to clarify the relationship between segmental glomerular necrosis (SGN) and progression of glomerular injury. The cases were divided into five groups according to the percentage of glomeruli with cellular/fibrocellular (C/F) crescents, fibrous adhesion and/or sclerosis: grade I, 0%; grade II, 20%; grade III, 20-50%; grade IV, 50-80%; and grade V, 80% or more. The serial sections revealed unequivocally focal occurrence of SGN in 39 cases (30%). Segmental glomerular necrosis was never found in the cases of grade I (0%, 0/28), while it appeared in those of grade II (33%, 12/36), grade III (46%, 13/28), grade IV (48%, 13/27) and grade V (11%, 1/9). The incidence of the cases with C/F crescents showed a similar tendency among the groups. In addition, focal C/F crescents were more frequent in cases with SGN (82%) than in those without SGN (24%). In particular, cellular crescents in 26 cases were formed in close proximity to SGN. These results suggested that SGN in IgA nephropathy was a more common finding than formerly evaluated and that it potentially participated in the progression of glomerular injuries closely associated with crescent formation. Unequivocally, focal occurrence of SGN corresponded well with the slowly progressive course of the glomerular disease.     

Thin basement membrane nephropathy as a cause of recurrent haematuria in childhood

A survey of 69 children presenting with recurrent or persistent haematuria and submitted to percutaneous renal biopsy at this hospital over a 17-year period, was performed to establish the incidence of thin basement membrane nephropathy (TBMN). A diagnosis of primary glomerular disease was established in 44 (IgA nephropathy in 16, Alport's syndrome in 13 and other varieties of glomerulonephritis in 15). Of the remaining 25 patients in whom light microscopical and immunochemical examination revealed no abnormalities, material for electron microscopy was available in 11. In eight of these (five of whom had a family history), TBMN was diagnosed on the basis of ultrastructural morphometric evaluation of glomerular basement membrane thickness. Assuming a similar proportion of the remaining 14 patients with renal biopsy specimens normal by light microscopy had TBMN, the probable frequency of this abnormality in the whole series would be 26%, very similar to that of IgA nephropathy. In the eight TBMN patients the mean glomerular basement membrane thickness ranged between 181 and 236 nm, whilst in 'control' biopsies from children with 'minimal change' nephrotic syndrome or IgA nephropathy, the mean thickness ranged between 242 and 333 nm.     

Binding capacity and pathophysiological effects of IgA1 from patients with IgA nephropathy on human glomerular mesangial cells

IgA deposition in glomerular mesangium and the interaction with mesangial cells may well be the final common pathway to IgA nephropathy (IgAN). Altered hinge-region O-glycosylation of IgA1 from patients with IgAN may predispose to mesangial deposition and activation of the mesangial cell (MC) by IgA1, via a novel IgA1 receptor, and may be a key event in the pathogensis of IgAN. The aim of this study was to investigate the binding capacity and biological effects of IgA1, from both patients with IgAN and healthy controls, on human mesangial cells (HMC). Serum IgA1 was isolated with jacalin affinity chromatography, heated to aggregated form (aIgA1) and labelled with (125)I. Binding capacity of aIgA1 in vitro to cultured primary HMC was evaluated by a radioligand binding assay and the specificity of binding was determined by a competitive inhibition assay. Intracellular calcium release was studied by confocal analysis and phosphorylation of extracellular signal-regulated kinase (ERK) was determined by Western blot analysis. Change of cell cycles was demonstrated by flow cytometry and HMC proliferation was evaluated by direct cell count. Expression of TGF-beta mRNA and production of supernatant fibronectin were tested by RT-PCR and indirect competitive ELISA, respectively. aIgA1 from both the patients with IgAN and normal controls bound to HMC in a dose-dependent, saturable manner, and was saturated at approximately 500 pmoles per 0.5 ml of aIgA1. aIgA1 from patients with IgAN, however, bound to HMC at a higher speed and Scatchard analysis revealed a Kd of (8.89 +/- 2.1) x 10(-8)m versus (4.3 +/- 1.2) x 10(-7)m for aIgA1 from healthy controls (P = 0.026).The binding was specific because it was only inhibited by unlabelled Mono-IgA1 (mIgA1) and not by serum albumin or IgG. aIgA1 from patients with IgAN could induce release of intracellular calcium, phosphorylation of ERK, DNA synthesis, proliferation of HMC, expression of TGF-betamRNA and secretion of fibronectin in HMC in a similar time-dependent manner as aIgA1 from healthy controls, but the effects were much stronger and the durations were much longer (P < 0.05, respectively). We conclude that aIgA1 from patients with IgAN has a higher binding capacity to HMC and stronger biological effects than aIgA1 from healthy controls. This suggests that direct interaction between IgA1 and HMC and subsequential pathophysiological responses may play an important role in the pathogenesis for IgAN.     

Immunohistochemical study of the membrane attack complex of complement in IgA nephropathy

Summary The localization of the membrane attack complex of complement (MAC) was examined in the normal human kidneys and in biopsy specimens from patients with primary IgA nephropathy by immunofluorescent and immunoelectron microscopies. Immunofluorescent staining for MAC was significantly more intense than in the normal kidneys, and was observed in the mesangium and occasionally along the glomerular capillary walls of 22 of 30 patients with IgA nephropathy. By dualstaining, the MAC deposits were generally concordant with the deposits of IgA, C3, C5 and C9, or of IgG, when present. C1_q or C4 was infrequently observed in the glomeruli. Immunoelectron microscopy revealed various staining patterns of glomerular MAC deposition; homogeneous fine-granular staining beneath the glomerular basement membrane (GBM) in the paramesangial zone, patchy staining within the mesangial electron dense deposits (EDD), and ring-shaped or ribbon-like staining, associated with the striated membrane structures (SMS), in the matrix of the mesangium, GBM and tubular basement membrane (TBM). This study suggests that the terminal complement system is activated, mainly by an alternative complement pathway mechanism, in the mesangium of IgA nephropathy, and is associated with the paramesangial lesion and EDD. MAC deposition in glomerular SMS may also result from in situ activation rather than trapping from the circulation. There was little correlation between glomerular MAC deposition and proteinuria or renal histology of patients with IgA nephropathy.