Demonstration of secretory IgA in kidneys of patients with IgA nephropathy.

BACKGROUND: Recently we reported a possible role for secretory IgA (SIgA) in IgA nephropathy (IgAN), as suggested by increased serum levels in patients with active disease and accumulation of SIgA in a glomerular eluate. Therefore, we attempted to find support for these findings by analysis of the presence of SIgA in biopsies of IgAN patients. METHODS: Renal biopsies of 26 patients with biopsy-proven IgAN were analysed for the presence of SIgA and complement proteins. RESULTS: In 15% mesangial deposition of SIgA was demonstrated, using a specific staining for secretory component (SC) and colocalization with IgA. The presence of SIgA in these biopsies showed a strong correlation with deposition of mannose-binding lectin (MBL) and C4d. Moreover, we observed a strong colocalization between SIgA and MBL or C4d. This local complement activation has previously been linked to more severe renal disease. CONCLUSIONS: Therefore, these data provide additional evidence for a pathogenic role for SIgA in IgA nephropathy.     

Association of secretory IgA with clinical pathological characteristics and complement activation in IgA nephropathy

Objective To further investigate the association among clinical pathology, complement activation and renal secretory IgA (SIgA) deposition in patients with IgA nephropathy (IgAN). Methods The activation of serum complements were detected by immunoturbidimetry and ELISA. Renal deposition of SIgA and activation of complements were detected by immunofluorescence. Then the association among clinical pathology, complement activation and renal SIgA deposition were analyzed in IgAN patients. Results In all 201 patients with IgAN,59 patients had SIgA deposition with higher incidences of mucosal infection history and hematuria (P＜0.05), lower levels of serum cystatin C, β2 microglobulin and lower tubulointerstitial lesion grades and T?grade in the Oxford classification (P＜0.05), when compared with patients without SIgA deposition. Both alternative and mannose binding lectin (MBL) pathways were activated in patients with or without SIgA deposition. Patients with MBL pathway activation had lower estimate glomerular filtration rate (P＜0.01), higher serum creatinine, higher proportion of glomerulosclerosis and S?grade in the Oxford classification, more severe tubulointerstitial lesion (P＜0.05). Conclusions Compared with patients without SIgA deposition, patients with SIgA deposition have a stronger link to mucosal immune. The deposition of SIgA is associated with different clinical and pathological manifestations; however, the complement activation is similar in both groups of patients. Patients with MBL pathway activation show more severe kidney injury.     

A pathogenic role for secretory IgA in IgA nephropathy

IgA nephropathy (IgAN) is characterized by deposits of IgA in the renal mesangium. It is thought that deposits of IgA mainly involve high molecular weight (HMW) IgA1. However, there is limited information on the exact composition of HMW IgA in these deposits. In this study, we investigated the presence of secretory IgA (SIgA) in human serum and in the glomerular deposits of a patient with IgAN. Furthermore, we analyzed the interaction of SIgA with mesangial cells. With enzyme-linked immunosorbent assay, SIgA concentrations in the serum of IgAN patients and healthy controls were measured. Both patients and controls had circulating SIgA that was restricted to the HMW fractions. Patients tended to have higher levels of SIgA, but this difference was not significant. However, in patients with IgAN, high serum SIgA concentrations were associated with hematuria. Binding of size-fractionated purified serum IgA and SIgA to mesangial cells was investigated with flow cytometry. These studies showed stronger binding of SIgA to primary mesangial cells compared to binding of serum IgA. Importantly, after isolation and elution of glomeruli from a nephrectomized transplanted kidney from a patient with recurrent IgAN, we demonstrated a 120-fold accumulation of SIgA compared to IgA1 in the eluate. In conclusion, we have demonstrated that SIgA strongly binds to human mesangial cells, and is present in significant amounts in serum. Furthermore, we showed that SIgA is accumulated in the glomeruli of an IgAN patient. These data suggest an important role for SIgA in the pathogenesis of IgAN.     

An increased polymeric IgA level is not a prognostic marker for progressive IgA nephropathy.

BACKGROUND: Elution of IgA from renal biopsies of patients with primary IgA nephropathy (IgAN) has suggested that mesangial IgA deposits are mainly multimeric in nature. This macromolecular IgA consists of dimeric and polymeric IgA and may be derived from the circulation. In children with IgAN, circulating macromolecular IgA levels correlate with bouts of macroscopic haematuria, but in adults a correlation with disease activity is less clear. Therefore, we have designed a novel method to assess the levels of polymeric IgA (pIgA) in sera from patients and controls. METHODS: A novel precipitation assay using recombinant CD89 was developed to measure pIgA. Polymeric IgA levels were measured in serum samples obtained from healthy volunteers (n = 21) and patients with IgAN (n = 51). Subsequently, serum pIgA levels were correlated with clinical parameters of disease. RESULTS: Serum pIgA levels were significantly increased in patients with IgAN. However, pIgA concentrations relative to total IgA were significantly lower in sera of patients with IgAN. No correlation was found between serum pIgA levels and clinical parameters of IgAN, such as decline of glomerular filtration rate, haematuria or proteinuria. CONCLUSIONS: Although absolute levels of serum pIgA are increased in patients with IgAN as compared with controls, levels of pIgA relative to total serum IgA are lower. No significant correlation was found between serum concentrations of pIgA and clinical parameters of disease. These data support the notion that it is not the size alone, but the physicochemical composition of the macromolecular IgA that is the key factor leading to mesangial deposition.     

Pathogenic role of the IgA molecule in IgA nephropathy

SUMMARY: Deposits of IgA together with complement in different body tissues support the hypothesis that IgA can trigger inflammatory mechanisms. IgA nephropathy (IgAN) is characterized by predominant mesangial IgA₁ deposits of a polymeric nature. So far, the mechanism of polymeric IgA₁ deposition in the kidney mesangium is poorly understood in IgAN. the exact pathophysiological sequel preceding renal fibrosis following the mesangial deposition of IgA immune complexes remains speculative. Recent in vitro studies revealed that binding of IgA to mesangial cells led to increased expression of growth factors, cytokines, and integrins. the release of these proinflammatory factors is likely to enhance inflammatory injury. In addition, the local renin-angiotensin system present in renal tissues also contributes to renal fibrosis through the activation of transforming growth factor-β. the question of whether polymeric IgA isolated from patients with IgAN exerted any upregulatory effect on the synthesis of macrophage migration inhibitory factor (MIF) and components of the renin-angiotensin system in human mesangial cells was explored. the in vitro studies revealed that polymeric IgA from IgAN patients upregulated the gene expression of renin and MIF in human mesangial cells in a dose-dependent manner. These findings further support the notion that glomerular deposition of IgA is not only a pathological epiphenomenon of IgAN, but that polymeric IgA exerts a pathophysiologic effect on the mesangial cells leading to renal fibrosis.     

Aberrantly glycosylated serum IgA1 are closely associated with pathologic phenotypes of IgA nephropathy

BACKGROUND: IgA nephropathy (IgAN) is the most common glomerulonephritis with various histologic and clinical phenotypes. The mechanisms underlying the pathogenesis of IgAN remained unclear. But now altered O-glycosylation of serum IgA1 observed in these patients was considered to be a key contributory factor. The aim of the current study is to investigate whether aberrantly glycosylated IgA1 was associated with pathologic phenotypes of IgAN. METHODS: Sera from 107 patients with IgAN recently diagnosed were collected. Fifty patients were with mild mesangial proliferative IgAN, the others were with focal proliferative and sclerosing IgAN. Sera from 22 normal blood donors were used as normal controls. Biotinylated lectins were used in enzyme-linked immunosorbent assay (ELISA) to examine different glycans on IgA1 molecules. The alpha2,6 sialic acid was detected by elderberry bark lectin (SNA), the exposure of terminal galactose (Gal) and N-acetylgalactosamine (GalNAc) were detected by arachis hypogaea [peanut agglutinin (PNA)] and vilsa villosa lectin (VVL), respectively. The serum IgA1 glycans levels corrected by serum IgA1 concentrations were compared between patients and controls. RESULTS: Reduced terminal alpha2,6 sialic acid (1.16 +/- 0.21 vs. 0.98 +/- 0.31) (P= 0.008) and galactosylation (0.30 +/- 0.29 vs. 0.16 +/- 0.19) (P= 0.029) increased exposure of (GalNAc) (0.00 vs. 0.03) (P= 0.024) were demonstrated in serum IgA1 from patients with IgAN as compared with those in controls. More important, the exposures of 2,6 sialic acid and Gal were significantly decreased, especially in patients with focal proliferative and sclerosing IgAN compared with that in patients with mild mesangial proliferative IgAN (0.91 +/- 0.34 vs. 1.05 +/- 0.25) (P= 0.014) (0.108 +/- 0.137 vs. 0.221 +/- 0.219) (P= 0.018). However, no significant difference was found between patients with mild mesangial proliferative IgAN and normal controls (P > 0.05). The exposure of GalNAc of serum IgA1 from patients with focal proliferative and sclerosing IgAN was significantly higher than that of controls (P= 0.017), but had no statistical difference with that of patients with mild mesangial proliferative IgAN. CONCLUSION: The desialylation and degalactosylation of IgA1 in sera of patients with IgAN were closely associated with pathologic phenotypes.     

Glomerular activation of the lectin pathway of complement in IgA nephropathy is associated with more severe renal disease

IgA nephropathy (IgAN) is characterized by glomerular co-deposition of IgA and complement components. Earlier studies showed that IgA activates the alternative pathway of complement, whereas more recent data also indicate activation of the lectin pathway. The lectin pathway can be activated by binding of mannose-binding lectin (MBL) and ficolins to carbohydrate ligands, followed by activation of MBL-associated serine proteases and C4. This study examined the potential role of the lectin pathway in IgAN. Renal biopsies of patients with IgAN (n=60) showed mesangial deposition of IgA1 but not IgA2. Glomerular deposition of MBL was observed in 15 (25%) of 60 cases with IgAN and showed a mesangial pattern. All MBL-positive case, but none of the MBL-negative cases showed glomerular co-deposition of L-ficolin, MBL-associated serine proteases, and C4d. Glomerular deposition of MBL and L-ficolin was associated with more pronounced histologic damage, as evidenced by increased mesangial proliferation, extracapillary proliferation, glomerular sclerosis, and interstitial infiltration, as well as with significantly more proteinuria. Patients who had IgAN with or without glomerular MBL deposition did not show significant differences in serum levels of MBL, L-ficolin, or IgA or in the size distribution of circulating IgA. Furthermore, in vitro experiments showed clear binding of MBL to polymeric but not monomeric patient IgA, without a significant difference between both groups. Together, these findings strongly point to a role for the lectin pathway of complement in glomerular complement activation in IgAN and suggest a contribution for both MBL and L-ficolin in the progression of the disease.     

雷公藤内酯醇对IgA肾病大鼠的治疗作用及对肾系膜区CD71表达的影响

目的：观察雷公藤内酯醇（triptolide,TP）对IgA肾病（IgAN）大鼠肾系膜区CD71表达的影响及其对IgAN的治疗作用。方法：将雄性SD大鼠随机分为正常组、IgAN模型组（模型组）、IgAN＋TP干预组（TP组）、IgAN＋泼尼松干预组（Pred组）,每组8只。采用牛血清白蛋白（BSA）＋葡萄球菌肠毒素（SEB）＋四氯化碳（CCl4）的方法建立IgAN大鼠模型,TP组给予TP100μg·kg^-1·d^-1,Pred组给予Pred5.0mg·kg^-1·d^-1灌胃。分别于0、7、11周测24h尿蛋白定量及尿红细胞计数。12周处死大鼠取血测血肌酐（Scr）、尿素氮（BUN）;肾组织行光镜、荧光、电镜观察病理学改变。并对系膜区IgA沉积及CD71表达水平作半定量分析。RT-PCR法检测CD71mRNA在肾组织中的表达水平。结果：造模7周后模型组、TP组、Pred组大鼠尿蛋白及红细胞均较正常组显著增多,第11周时TP组及Pred组尿蛋白及红细胞较模型组显著减少,TP组尿红细胞下降尤为明显。模型组大鼠光镜下肾系膜基质增生,系膜细胞增多,部分毛细血管攀闭塞;荧光下IgA呈团块状在系膜区沉积;电镜下足突融合,系膜增生,有块状电子致密物沉积,TP组及Pred组病理较模型组显著改善,正常组未见病理改变。CD71的蛋白及mRNA水平在模型组大鼠肾组织高表达,TP组及Pred组表达显著减弱,正常组微弱表达。CD71在肾系膜区的表达与IgA的沉积呈正相关。结论：IgAN大鼠肾系膜区CD71高表达,与IgA的沉积呈正相关,TP能显著减少CD71在肾系膜区的表达,减少IgA沉积,改善临床及病理损伤指标。可见TP通过下调系膜区中CD71的表达,进而减少IgA的沉积是TP治疗IgAN的机制之一。     

不同类型血脂异常对IgA肾病临床及病理特征的影响

目的探讨不同类型血脂异常对IgA肾病临床及病理特征的影响。 方法共纳入283例原发性IgA肾病患者,收集临床资料及病理资料进行回顾性分析。将患者分为：高胆固醇(H－TC)组48例( TC≥ 6.22 mmol/L,TG<1.7 mmol/L);高甘油三脂(H－TG)组48例(TG≥2.26 mmol/L,TC<5.18 mmol/L);低高密度脂蛋白(L－HDL)组34例(HDL－C<1.04 mmol/L,TC<5.18 mmol/L,TG<1.7 mmol/L],同时收集IgAN血脂正常者(153例,TG<1.7 mmol/L、TC<5.18 mmol/L、HDL－C>1.04 mmol/L)作为对照组。对各组患者的一般情况、临床指标及病理分型(牛津分型)进行比较,并采用逐步回归分析方法进行多重线性回归分析探讨影响患者肾小球滤过率(eGFR)的因素。 结果H-TC组24 h尿蛋白量高于血脂正常组(Z＝－2.979, P＝0.003),血清白蛋白低于血脂正常组(t＝2.606,P<0.001)。H-TG组,身体质量指数(BMI)、血清尿酸高于血脂正常组(t＝3.982,t＝5.056;P<0.001), eGFR低于血脂正常组(t＝2.011,P＝0.045)。L-HDL组BMI高于血脂正常组(t＝2.946,P＝0.004),eGFR低于血脂正常组(t＝2.498,P＝0.013),肾小管萎缩/间质纤维化程度高于血脂正常组(χ²＝8.284,P<0.017)。回归方程结果显示年龄、收缩压、尿酸与eGFR呈负相关关系(P<0.05),血清TC与eGFR亦呈负相关关系(95%CI：－5.228～－0.312,t＝－2.220,P＝0.027)。血清HDL与eGFR呈正相关关系( 95%CI：1.469～7.468,t＝2.935,P＝0.004),该模型经检验有统计学意义(F＝11.838,P<0.001)。 结论H-TC、H-TG、L-HDL血症均可能加重IgA肾病的临床损害,且L-HDL血症者肾小管间质受损更严重。降低血清TC,提高血清HDL可能有助于IgA肾病患者改善预后。     

IgA serology in recurrent and non-recurrent IgA nephropathy after renal transplantation

BACKGROUND: This study investigated whether abnormal circulation of macromolecularIgA and IgA with altered glycosylation or electrical chargeplays a role in the recurrence of IgA nephropathy (IgAN) aftertransplantation. STUDY DESIGN: A total of 92 renal transplant patients were enrolled; 52 IgANpatients and 40 with other non-IgAN. The IgAN group included10 patients showing IgA mesangial deposits in the grafted kidneys(recurrent group) and 10 who did not (immunohistochemicallyproven non-recurrent group). In addition another 22 IgAN transplantpatients were clinically free of recurrent disease. METHODS: The analyses included macromolecular IgA (IgAIC) detected bythe conglutinin assay (K), heavy IgA precipitated in 2.5% polyethyleneglycol (PEG), IgA-fibronectin aggregates (IgA/F Aggr), mixedIgA/IgGIC, IgA binding to mesangial matrix components (fibronectin,laminin, type IV collagen) or polycations (poly-L-lysine) andIgA with altered glycosylation (Jacalin-binding assay). RESULTS: After transplantation, IgAN patients displayed significantlyhigher mean levels for each variable measured than non-IgAN(ANOVA, P <0.05). By stepwise regression analysis, the bindingof IgA to fibronectin had the highest coefficient. By comparingdata in recurrent and clinically non-recurrent IgAN, we observedthat two groups could be distinguished by the results of thetwo assays for macromolecular IgA (conglutinin IgAIC and IgA-fibronectinaggregates) and IgA with increased affinity for type IV collagen(P <0.05). When the selected group of immunohistochemicallyproven non-recurrent IgAN was compared to the recurrent one,a statistically significant difference was found only for thebinding of IgA to type IV collagen (P<0.05). Data from thistest were significantly related with proteinuria (P<0.05)and microscopic haematuria (P <0.04). CONCLUSION: Even though the IgA serology of renal transplant IgAN patientsshows peculiar features and recurrent and non-recurrent IgANdiffer in many aspects, the prevalence of positive data in thetwo groups had no predictive value. This suggests that the recurrenceof IgAN is modulated by factors affecting the interaction betweencirculating abnormal IgA and mesangial cells and/or matrix.     

血清低半乳糖化IgA1测定对鉴别IgA肾病的临床价值

目的 确定血清低半乳糖化IgA1对鉴别诊断IgA肾病的临床价值。 方法 以原发性肾小球疾病患者91例为研究对象，接受肾活检并留取血清；以健康体检者20例血清作为对照。血清标本先用装有耦联蚕豆凝集素的微球进行微量离心柱法分离并洗脱，获得低半乳糖化IgA1。再以凝集素HAA（Helix aspersa）用ELISA法定量检测异常糖基化IgA1（HAA-IgA1）。分析血清低半乳糖IgA1升高在鉴别诊断IgA肾病方面的临床价值。 结果 48例IgA肾病患者HAA-IgA1水平[（83.7±41.0） U]高于健康对照组[（52.6±22.9） U]及43例其他原发性肾小球疾病患者组[（49.2±27.3） U]（均P < 0.01）。而该43例中，非IgA系膜增殖性肾炎患者22例（51%）的HAA-IgA1水平[（47.6±21.5） U]亦显著低于IgA肾病患者。以肾穿刺病理诊断为金标准，所绘制ROC曲线面积为0.797，面积的标准误为0.047（P < 0.01）；鉴别诊断IgA肾病的灵敏度为72.9%，特异度为72.1%，准确度为72.5%。 结论 应用微量离心柱法联合ELISA法检测IgA肾病患者血清低半乳糖IgA1对于鉴别诊断IgA肾病具有一定临床价值。     

Clinicopathological features and outcomes of primary IgA nephropathy patients with chronic tonsillitis

Objective To explore the clinicopathological features and renal outcomes of primary IgA nephropathy (IgAN) patients with chronic tonsillitis. Methods Patients with biopsy-proven primary IgAN admitted to The First Affiliated Hospital, Sun Yat-sen University from January 2006 to December 2011 were enrolled. The clinicopathological features and renal outcomes of patients with and without chronic tonsillitis were retrospectively compared. The primary outcome was progression to end stage renal diseases and/or doubling of serum creatinine. Results A total of 981 primary IgAN patients were enrolled and 98 patients (9.99%) had a history of chronic tonsillitis. Compared with patients without chronic tonsillitis, IgAN patients with chronic tonsillitis exhibited significantly higher prevalence of acute episodes of tonsillitis as a predisposition (P＜0.001), higher serum IgA levels (P=0.012), and higher prevalence of macrohematuria (P=0.006). No significant difference in renal pathological features was observed in patients with and without chronic tonsillitis. Moreover, the renal outcomes were similar as regards IgAN patients with and without chronic tonsillitis. Conclusion IgAN patients with chronic tonsillitis had higher prevalence of acute episodes of tonsillitis and macrohematuria as well as higher serum IgA levels. However, IgAN patients with and without chronic tonsillitis showed no significant difference in renal pathological features and renal outcomes.     

Clinical-pathologic features and outcomes of IgA nephropathy patients with IgM deposition

Objective To determine the correlation of IgM deposition with clinic-pathological features and outcomes of IgA nephropathy patients. Methods A total of 1060 patients, who were diagnosed as IgA nephropathy by renal biopsies between 2001 and 2007 in Guangxing Hospital were enrolled. According to immunofluorescent test, patients were divided into patients with mesangial IgM deposition and patients without IgM deposition. Renal survival curves were assessed by Kaplan-Meier method. The effect of IgM deposition on outcomes of IgA nephropathy patients was examined by univariate and multivariable Cox proportional-hazards regression. Results Among 1060 IgA nephropathy patients, there were 750 patients with IgM deposition and 310 patients without IgM deposition. (1) Urinary protein and uric acid in patients with IgM deposition were significantly higher than those in patients without IgM deposition (all P＜0.05). Other clinical indicators shown no statistical difference (all P＞0.05). Moreover, IgM deposition patients had higher serum IgA, serum IgG and serum IgM (all P＜0.05). (2) In pathological indicators, IgM deposition patients had more segmented sclerosis or adhesions (S1 of Oxford classification), activity lesions as inflammatory cell infiltration and mesangial proliferation, and chronic pathological changes as tubular atrophy, segmented glomerular damage than patients without IgM deposition (all P＜0.05). (3) All patients were followed-up for a median of 89.7(61.8, 113.4) months, Kaplan-Meier analysis revealed that kidney survival rate was significantly lower in IgM deposition patients compared with patients without IgM deposition (Log-rank χ2=4.95, P=0.026). In a univariate Cox hazards regression mode, IgM deposition was a risk factor for poor prognosis of IgA nephropathy patients (HR=1.597, 95%CI 1.053-2.422, P=0.027). However, in a multivariable Cox analysis, IgM deposition shown no influence on outcomes of IgA nephropathy patients (HR=1.409, 95%CI 0.921-2.156, P=0.114). Conclusions IgA nephropathy patients with IgM deposition have higher urinary protein, and more serious pathological damage and immune fluorescence deposition. IgM deposition affects renal survival of IgA nephropathy, while IgM deposition is not an independent risk factor for prognosis of IgA nephropathy.     

移植肾IgA肾病临床病理及预后分析

目的探讨移植肾IgA肾病(IgAN)复发或新发的诱因及移植肾生存的危险因素。方法选取2012年11月至2018年12月浙江大学医学院附属第一医院经肾活检确诊为移植肾IgAN的患者,按照血肌酐(Scr)增高水平、估算肾小球滤过率(eGFR)下降率分为稳定组(Scr升高值<20μmol/L,eGFR下降率<10%)和进展组(Scr增高但未达翻倍值,30%相似文献   

Mesangial IgA1 in IgA nephropathy exhibits aberrant O-glycosylation: observations in three patients

BACKGROUND: In IgA nephropathy (IgAN), circulating IgA1 molecules display an abnormal pattern of O-glycosylation. This abnormality may potentially contribute to mesangial IgA1 deposition, but this is unproven because the O-glycosylation of mesangial IgA1 has not been analyzed. METHODS: IgA1 was eluted from glomeruli isolated from the kidneys of three IgAN patients obtained after nephrectomy or at postmortem. Serum from these patients, other patients with IgAN, and controls was subjected to the same treatment as the glomerular eluates. The O-glycosylation of eluted and serum IgA1 was measured by lectin binding using an enzyme-linked immunosorbent assay-based system. RESULTS: In all three cases, the lectin binding of IgA1 eluted from the glomeruli of IgAN patients was markedly higher than that of the serum IgA1 of the same individual, and also all but one of a series of serum IgA1 samples from other patients and controls. CONCLUSIONS: The higher lectin binding of glomerular compared with serum IgA1 suggests that O-glycosylated IgA1 molecules abnormally and selectively deposit in the kidney. These results provide the first evidence that mesangial IgA1 is abnormally O-glycosylated, and support a direct role for abnormal IgA1 O-glycosylation in the mechanism of mesangial IgA deposition in IgAN.     

IgA肾病患者血清IgA1与系膜细胞共培养上清诱导足细胞凋亡

目的 探讨IgA肾病(IgAN)患者血清IgA1与系膜细胞共培养上清对足细胞凋亡的影响。 方法 用Jacalin 亲和层析柱和Sephacryl S-200 分子筛纯化蛋白。单体IgA1（mIgA1）热聚合为聚合体IgA1（aIgA1）。实验分为患者上清组、健康上清组和对照组，系膜细胞分别与IgAN患者的aIgA1、健康对照的aIgA1和5%胎牛血清共培养，收集上清，与同步化的足细胞作用。流式细胞仪检测细胞凋亡情况。实时定量PCR 检测凋亡相关基因Bcl-2、Bax、Fas和Fas-L表达情况。 结果 患者上清可诱导足细胞凋亡，其凋亡率显著高于健康上清组和对照组[（28.5±5.9）%比（22.5±5.8）%、（20.5±4.5）%， 均P < 0.05]。患者上清可诱导足细胞Fas mRNA 升高，为对照组的1.89倍（P < 0.05）， 而Bcl-2 mRNA下调为对照组的72%（P < 0.05）。患者上清组的AngⅡ和TGF-β1水平均高于健康上清组[（13.2±3.4） ng/L比（8.2±2.3） ng/L，P < 0.05；（15.4±3.4） ng/L比（10.8±3.2） ng/L，P < 0.05]。 结论 IgAN患者血清IgA1与系膜细胞共培养上清可诱导足细胞凋亡，可能参与IgAN的进展。     

Clinical and pathological features of IgA nephropathy with macrohematuria in history

Objective To investigate the clinical and pathological characteristics of IgA nephropathy (IgAN) with macrohematuria (MH). Method 1512 consecutive patients with biopsy-proven IgAN diagnosed from January 2006 to December 2011 were enrolled, and divided into MH group and control group respectively, according to whether there existed episodes of MH before renal biopsy. The clinical and pathological characteristics were compared between two groups. Patients in MH group were then divided into three groups according to the interval from the last episode of MH to renal biopsy to clarify the concomitant clinicopathological changes associated with occurrence of MH. Results The rate of MH in history was 22.1%. MH group patients had significantly lower serum creatinine, slighter proteinuria, lower prevalence of hypertension and heavier microhematuria than control group (all P＜0.001). The prebiopsy durations were similar in two groups (P=0.627). In MH group, chronic pathological indicators, including global/segmental sclerosis, tubule atrophy/interstitial fibrosis were all slighter (all P＜0.001), whereas activity indicators, including necrosis lesions, crescents and mesangial proliferation were all more severe compared with control group (all P＜0.05). Those who underwent renal biopsy within 30 days of the last episode of MH had more severe proteinuria and microhematuria, higher prevalence of necrosis lesions, more severe crescents formation, and endothelial proliferation (all P＜0.05). Conclusions IgAN patients with MH in history have relatively milder clinical and chronic pathological manifestations, however more active pathological changes especially in those who suffer episode of MH recently.     

Soluble fibrin formation in the mesangial area of IgA nephropathy

Background Fibrin monomer and its derivatives in blood are found in an early stage of thrombosis. When they are produced in blood, they form complexes with fibrinogen, and they exist as soluble complexes named soluble fibrin (SF). As final insoluble products, cross-linked fibrin (XFb) is often observed in mesangial areas in active types of human glomerulonephritis. To clarify the mechanisms of mesangial SF production and its relationship to XFb deposition in IgA nephropathy (IgAN), an immunohistochemical study was conducted. Methods Nineteen patients with IgAN were studied. XFb was detected in renal biopsy specimens using anti-d-dimer antibody combined with plasmin exposure. SF was detected with a monoclonal antibody (IF-43), and factor V was detected with a specific rabbit antibody. The relationships of SF staining to the disease activity index, XFb deposition, and factor V staining was evaluated. Results XFb, factor V, and SF were observed in the mesangium in 14, 11, and 8, respectively, of a total of 19 specimens. SF had frequent staining in the proliferating areas, showing a significant relationship to XFb or factor V (P < 0.05). Furthermore, XFb, factor V, and SF depositions were markedly correlated with disease activity (P < 0.001 in each case). Conclusions These findings suggest that SF is formed in the mesangial area in active IgA nephropathy accompanied by mesangial proliferation, in particular, in its early stage.     

The pathogenic role of IgA1 O-linked glycosylation in the pathogenesis of IgA nephropathy

Numerous abnormalities of the IgA immune system have been reported in IgAN but the most consistent finding remains aberrant IgA1 O-linked glycosylation of the IgA1 hinge region. The defect comprises reduced galactosylation of O-linked N-acetylgalactosamine residues with or without changes in the terminal sialylation of the O-linked sugars. Aberrant O-galactosylation has been found in serum IgA1, in IgA1 isolated from tonsillar lymphocytes, and in IgA1 eluted from mesangial deposits. There is evidence that changes in IgA1 O-galactosylation lead to IgA immune complex formation and mesangial IgA deposition. Mesangial cells exposed to these IgA immune complexes proliferate and adopt a pro-inflammatory phenotype; they secrete cytokines, chemokines, growth factors and extracellular matrix components promoting glomerular inflammation and glomerulosclerosis. Recent evidence suggests that the control of IgA1 O-glycosylation is linked to class switching from IgD to IgA1 synthesis and that the pattern of IgA1 O-glycosylation may be programmed at the time of initial antigen encounter. IgA1 glycosylation varies between systemic and mucosal sites and the association of aberrant IgA1 galactosylation with low affinity, polymeric IgA1 antibodies against mucosal antigens suggests undergalactosylated IgA1 may in fact be a mucosal glycoform of IgA1. Although suited to the mucosal compartment, when these IgA1 glycoforms enter the systemic circulation in appreciable quantities they deposit in the mesangium and trigger glomerular inflammation. This review will discuss the evidence for the role of IgA1 O-glycosylation in the pathogenesis of IgAN and propose an explanation for the presence of aberrantly O-glycosylated IgA1 in the circulation of patients with IgAN.     

Low-antigen-content diet in the treatment of patients with IgA nephropathy

Since dietary macromolecular antigens can be involved in thepathogenesis of IgA nephropathy (IgAN), the effect of a low-antigen-contentdiet was evaluated in 21 patients (10 women, 11 men, mean age27.7±10 years) with immunohistochemical findings of activeIgAN. The diet was followed for a 14–24-week period (mean18.8±6); in all cases the effects of the treatment wereevaluated by clinical and serological parameters, and in 11patients also by repeat renal biopsy. After dietetic therapy a significant reduction of urinary proteinswas recorded (P< 0.001); in particular, heavy proteinuria(>1 g/day), present in 12 cases during the 6 months precedingthe treatment, was markedly reduced or disappeared in 11. Atposttreatment control biopsy mesangial and parietal depositsof immunoglobulins, complement C₅, fraction and fibrinogen weresignificantly reduced. The improvement of the objective parameterssuch as heavy proteinuria, a strong predictor of a poor prognosis,and of immunohistochemical alterations indicate that a low-antigendiet can positively affect patients with IgAN. These resultscould be ascribed to a reduction of nephritogenic food antigeninput and to a putative functional restoration of the mononuclearphagocytic system.