IgA肾病中足细胞损伤及其与蛋白尿的关系

目的 观察 IgA肾病（IgAN）患者足细胞损伤的各种表现，探讨其与蛋白尿的关系。 方法 收集35例伴有明显蛋白尿[尿蛋白量（24 h）>1.0 g]的IgAN患者肾活检组织作研究；以8例肾错构瘤患者术后切除肾和肾癌患者术后远离癌旁肾组织为正常对照。免疫组化方法观察肾组织细胞周期调节蛋白（p21、p27）、足细胞结构蛋白（nestin）、足细胞数目 （WT1）。用显微切割方法取出肾小球，通过实时定量PCR方法检测整合素（integrin）β1、nephrin和α辅肌动蛋白4（α-actinin 4）水平。电镜观察足细胞超微结构的改变。根据足细胞数目密度(Nv, n×106/μm3)将35例IgAN患者分为足细胞数目减少组（ Nv<52.49×106/μm3，n = 15）和足细胞数目正常组（Nv≥52.49×106/μm3，n = 20）。随访蛋白尿的转归情况，共18个月。 结果 （1）与正常对照组比较，IgAN患者肾小球内个别足细胞重新表达p21，而足细胞p27的表达明显降低（0.71±0.12比0.91±0.07，P < 0.05）。（2）IgAN患者足细胞nestin 蛋白表达比正常对照显著降低（13.40%±0.04%比 17.60%±0.04%，P < 0.05）；肾小球内integrin-β1 mRNA表达显著升高（12.54±5.20比1.02±0.30，P < 0.05），而nephrin及α-actinin4 mRNA无明显改变。（3）电镜下观察到明显的足突融合和足细胞从基底膜脱落。（4）IgAN患者足细胞数目密度比正常对照组显著减少(161.27±225.92比323.22±138.12，P < 0.05)，且与Lee氏分级相关。（5）足细胞数目密度、integrin-β1 mRNA与肾穿刺当时的尿蛋白量（24 h）呈负相关(r = -0.4483、-0.840, 均P < 0.05)。足细胞数目减少组较足细胞数目正常组的蛋白尿下降程度明显减少（P < 0.05）。 结论 伴蛋白尿的IgAN中存在足细胞的损伤，表现为足细胞周期调节蛋白、结构蛋白的改变，足突的融合及足细胞数目的减少，而足细胞损伤及足细胞数目减少会影响蛋白尿的发生和发展。     

IgA肾病患者血清aIgA1对足细胞增殖及nephrin分子表达的影响

目的：观察IgA肾病（IgA nephropathy,IgAN）患者与正常人的血清热聚合IgA1（aggregated IgA1,aIgA1）对足细胞增殖及nephrin分子表达的影响。方法：利用亲和层析联合分子筛层析法分离获得原发性IgAN患者与健康人血清单体IgA1（monomeric IgA1,mIgA1）,将mIgA1热聚合为aIgA1,分别刺激小鼠MPC5足细胞株,利用MTT法检测aIgA1对足细胞增殖的影响,用RT-PCR法检测aIgA1干预后足细胞nephrin分子基因表达水平的改变。结果：不同浓度aIgA1刺激组间足细胞MTT吸光度的差异有统计学意义（P〈0.05）。RT-PCR实验发现正常人及患者的aIgA1刺激足细胞后,均可以时间依赖性及剂量依赖性的方式下调nephrin mRNA的表达,且患者的aIgA1下调nephrin表达的作用更明显（P〈0.01）。结论：IgAN患者与正常人的aIgA1均可以影响足细胞增殖,并下调足细胞nephrin mRNA的表达。患者aIgA1对足细胞nephrin mRNA表达的下调作用较正常人明显,在疾病过程中IgA1可能是加重足细胞损伤的原因之一。     

调节性及辅助性T细胞在人类IgA肾病中的表达及意义

目的 探讨CD4+CD25high调节性T细胞（Treg）及辅助性T细胞亚群（Th1、Th2）比例失衡在IgA肾病（IgAN）免疫发病机制中的作用。 方法 用流式细胞仪检测IgAN患者外周血Treg及Th1、Th2的比例。以胞内染色技术检测叉头框蛋白3（FOXP3）的表达。Treg及Th1、Th2的比例与IgAN各项临床病理指标的相关性分析采用Spearman或Pearson相关分析法。 结果 IgAN患者外周血中Treg比例明显高于健康人[（2.14±0.82）％比（1.59±0.53）％，P ＜ 0.05]，与血IgA水平呈正相关（r = 0.397，P ＜ 0.05），与eGFR呈负相关（r = -0.376，P ＜ 0.05）。IgAN患者外周血中Th2细胞比例显著高于健康对照组[（2.57±0.72）％比（1.81±1.10）％，P ＜ 0.05]，与血IgA水平呈正相关（r = 0.468，P ＜ 0.05）。IgAN患者Th1/Th2比值显著低于健康对照组（5.75±1.89比12.73±9.79，P ＜ 0.05），但与临床各指标间没有相关性。 结论 IgAN患者体内存在T细胞亚群表达紊乱。Treg在外周血中的增多以及以Th2为优势的Th1/Th2失衡可能在IgAN的发病中起重要作用。     

敲低CD2相关蛋白的表达对足细胞黏附和胞质伸展功能的影响

目的 观察敲低足细胞CD2相关蛋白（CD2AP）表达对细胞黏附和胞质伸展功能的影响，并探讨其机制。 方法 用RPMI 1640培养基33℃下培养小鼠未分化足细胞系，转染针对CD2AP的小分子干扰RNA（siRNA），设无特异靶位点的scrambing 序列即control siRNA转染组作对照。48 h后将转染的足细胞制备成单细胞悬液，接种于预铺有Ⅳ型胶原蛋白的96孔板内，33℃下培养90 min后检测足细胞的贴壁率和细胞的伸展面积；流式细胞仪检测抑制CD2AP后足细胞的凋亡率以及在不同氨基核苷嘌呤霉素（PAN）刺激下足细胞的凋亡率；激光共聚焦显微镜下检测F肌动蛋白（F-actin）的分布变化；Western印迹和免疫共沉淀检测nephrin蛋白的表达及其磷酸化水平。 结果 转染CD2AP siRNA足细胞的黏附率为41.72%±6.07%，显著低于对照组64.46%±8.53%（P < 0.05）；细胞伸展的面积>200 μm2的比例（55.86％）亦显著低于对照组（73.61％）。转染CD2AP siRNA后48 h足细胞的凋亡率高于对照组[（5.73±0.61）％比（3.26±0.45）％，P < 0.05]。100 mg/L的PAN能明显诱导足细胞的凋亡，减少足细胞的黏附率（P < 0.05）。敲低CD2AP的表达后足细胞F-actin的分布发生明显的变化，nephrin蛋白表达和磷酸化水平下降（P < 0.05）。 结论 敲低CD2AP的表达使足细胞易于凋亡，影响细胞的黏附功能。足细胞骨架蛋白的紊乱和nephrin信号通路的抑制可能是足细胞黏附和伸展功能下降的机制。     

1,25(OH)2D3抑制嘌呤霉素氨基核苷酸肾病大鼠足细胞凋亡

目的 观察1，25（OH）2D3对嘌呤霉素氨基核苷酸（PAN）肾病大鼠足细胞凋亡的影响。 方法 72只雄性SD大鼠随机分为健康对照组（NC）、PAN组和1，25（OH）2D3治疗组 [1，25（OH）2D3 0.2 μg·kg-1·d-1灌胃]。一次性尾静脉注射PAN 100 mg/kg体质量建立足细胞损伤的PAN肾病动物模型。于3、7、14、21 d分批处死动物，分别检测不同时间点尿蛋白量（24 h）和肾功能。光镜和透射电镜观察肾组织学改变。TUNEL法检测足细胞凋亡。RT-PCR、免疫荧光、免疫组化分别检测nephrin、TGF-β1 mRNA和蛋白的表达。Western印迹检测磷酸化（p）-Smad2/3的表达。 结果 （1）PAN组各时间点BUN、Scr、尿蛋白量（24 h）[7 d时，（20.26±4.87） mg比（1.01±0.41） mg，P < 0.01]均高于同期的NC组，而肾小球足细胞显著减少[14 d时，(10.9±4.2) 个/肾小球切面比(31.9±6.2)个/肾小球切面，P ＜ 0.01]，且足突增宽融合。1，25（OH）2D3治疗组各时间点尿蛋白量（24 h）[7 d时（9.95±3.82） mg]和BUN、Scr显著低于PAN组（P < 0.05），且肾脏病理改变减轻。（2）PAN组7 d时nephrin mRNA和蛋白的表达显著降低，nephrin由正常的沿毛细血管襻线状分布向颗粒状、团快状改变，足细胞凋亡数显著增加[14 d时，（37.4±7.9）个/肾小球切面]。与PAN组相比，1，25（OH）2D3治疗组各时间段nephrin mRNA和蛋白的表达显著增加，且保持着正常的沿毛细血管襻线状分布，足细胞凋亡数显著减少[14 d时，(21.9±6.2) 个/肾小球切面，P < 0.01]。（3）PAN组TGF-β1 mRNA和蛋白的表达以及p-Smad2/3蛋白的表达均高于NC组（P < 0.01），1，25（OH）2D3治疗组TGF-β1 mRNA和蛋白的表达以及p-Smad2/3蛋白的表达低于PAN组（P < 0.01）。 结论 1，25（OH）2D3能有效地抑制PAN诱导的足细胞凋亡，减少尿蛋白，其对足细胞损伤的保护作用可能与抑制TGF-β1信号通路有关。     

伴足细胞尿的IgA肾病的临床病理特征

目的 探讨伴足细胞尿的IgA肾病（IgAN）患者的临床病理特点。方法 入选IgAN患者36例,其中男性20例,女性16例,平均年龄（34．1±12．2）岁。10例健康志愿者为健康对照。足细胞排泄的定量检测采用尿沉渣涂片免疫组化染色直接计数。进行尿液足细胞排泄与肾脏病理的相关分析。结果 （1）IgAN患者尿细胞podocalyxin阳性率为61%,健康对照组为0（P＜0．05）。（2）与非大量蛋白尿（＜3．0 g/24 h）IgAN患者比较,大量蛋白尿（≥3．0 g/24 h）IgAN患者的尿液足细胞检测阳性率、尿液足细胞排泄数、足细胞与尿肌酐的比值以及足细胞占尿液小管上皮细胞的百分数均显著增高（P＜0．05）。IgAN患者足细胞排泄水平与蛋白尿水平呈正相关（r=0．446,P=0．007）。（3）与无足细胞尿的患者比较,伴足细胞尿的IgAN患者的蛋白尿水平显著增高,血浆白蛋白水平显著降低,肾小管上皮细胞与尿肌酐的比值亦显著增高（P＜0．05）。但伴与不伴足细胞尿的2组IgAN患者在年龄、性别、血压、Scr、血红蛋白水平以及血浆脂质代谢等方面差异均无统计学意义（P＞0．05）。（4）尿足细胞的排泄与细胞新月体或细胞纤维性新月体、小球血管襻腔狭窄和足突广泛融合病变有关,而与系膜、内皮细胞病变及局灶基底膜增厚无关。伴足细胞尿的患者肾小球和肾小管间质纤维化更明显（P＜0．05）。伴有新月体的患者其尿液足细胞排泄水平、尿液上皮细胞和管型的排泄均增加（P＜0．05）。结论 足细胞尿不仅是IgAN患者肾小球损伤的结果,也是IgAN患者活动性损伤的指标。足细胞尿排泄的水平与蛋门尿水平呈正相关,与肾脏病理类型也有一定的关系。     

雷公藤甲素对IgA肾病患者外周血单个核细胞炎性反应及凋亡的影响

目的 探讨IgA肾病(IgAN)患者外周血单个核细胞（PBMC）炎性因子分泌及自身凋亡状态,以及雷公藤甲素(TP) 对其调节的相关机制。 方法 取IgAN患者（n=29）及健康人（n=16）外周血,分别通过酶联免疫吸附试验（ELISA）和硝酸还原酶法（Griess法）检测血浆肿瘤坏死因子α（TNF-α）、白细胞介素6（IL-6）和一氧化氮(NO)表达情况。体外培养IgAN患者PBMC,以不同浓度TP刺激PMBC,四唑盐比色间接法（MTT）检测TP对细胞生长的抑制效应。根据MTT结果,分别分为IgAN患者PBMC组、植物血球凝集素（PHA,10 mg/L,促细胞分裂原）模型组和PHA（10 mg/L）+TP（12.5 μg/L、25 μg/L）处理组。ELISA法检测上清液中TNF-α、IL-6的分泌情况;Griess法检测上清液中NO含量;流式细胞仪分析细胞凋亡率;RT-PCR法、Western印迹法检测PBMC中B细胞淋巴瘤/白血病-2（Bcl-2）、Bcl-2相关X蛋白（Bax）、半胱天冬蛋白酶（caspase）-9、caspase-3基因和蛋白表达变化。 结果 IgAN患者血浆TNF-α[（131.57±50.61） ng/L比（30.24±18.93） ng/L,P < 0.01],IL-6[（76.36±25.21） ng/L比（35.08±16.59） ng/L,P < 0.01]和NO[（46.36±12.93） μmol/L比（26.61±10.87） μmol/L,P < 0.01]均显著高于健康人,PBMC凋亡率亦显著高于健康人[（16.88±5.66）%比（8.67±3.87）%,P < 0.01]。TP可抑制IgAN患者PBMC分泌 TNF-α、IL-6 和NO,诱导其凋亡;也可抑制Bcl-2表达,增加Bax、caspase-9、caspase-3表达。 结论 IgAN患者体内PBMC处于高度活化状态,并且凋亡率增高。TP能有效抑制IgAN患者PBMC的炎性活化状态,并可能通过线粒体途径改变Bcl-2蛋白家族抗凋亡因子和促凋亡因子平衡而诱导IgAN患者PBMC凋亡。     

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。     

IgA肾病患者IgA1对足细胞nephrin mRNA表达的影响

近年研究发现IgA肾病患者的血清IgA1与正常人相比具有明显的异质性,其中起致病作用的主要是聚合型IgA1（polymeric IgA1,pIgA1）。新近研究也发现IgA肾病（IgAN）不仅是系膜细胞受累的疾病,而且在疾病的发生发展过程中也存在着足细胞的破坏。目前关于患者血清IgA1分子异常和足细胞损伤之间有何关系尚不清楚,我们亦未检索到相关报道。本研究拟观察IgAN患者血清IgA1对足细胞分子nephrin表达的影响。     

骨髓间充质干细胞促进大鼠IgA肾病修复

目的 观察骨髓间充质干细胞（MSC）对大鼠IgA肾病有无修复作用，并探讨其可能的机制。 方法 SD大鼠随机分为MSC注射组、生理盐水（NS）组及健康对照组。前两组以牛血清白蛋白(BSA)+葡萄球菌肠毒素B（SEB）＋皮下注射四氯化碳（CCl4）的改良法建立IgA肾病模型。体外连续培养SD大鼠MSC并通过流式细胞仪和成骨成脂细胞诱导分化鉴定MSC，用5-溴脱氧尿嘧啶核苷（BrdU）体外标记培养的MSC。移植后1周及4周分别观察3组的体质量、尿蛋白量（24 h）、肾功能、肾脏病理变化、IgA荧光沉积变化；ELISA法检测尿中的MCP-1、TGF-β1量；RT-PCR法检测肾组织中MCP-1、TGF-β1 mRNA的表达情况；免疫组化观察细胞因子及BrdU标记的MSC在肾组织中的分布情况。 结果 移植后1周，MSC组尿蛋白量（24 h）（36.86±4.78） mg，Scr（53.50± 6.28） μmol/L；NS组尿蛋白量（24 h）(66.98±5.86) mg，Scr (82.50±8.36) μmol/L，两组差异有统计学意义（均P < 0.05）；同时，MSC组MCP-1、TGF-β1在尿中的含量及肾脏中表达均显著低于NS组（均P < 0.05）。移植后4周，MSC组体质量、肾脏病理变化、IgA荧光沉积与NS组差异有统计学意义；MCP-1、TGF-β1在尿中的含量及肾脏中的表达与健康对照组差异无统计学意义。随时间延长，BrdU标记的MSC在肾组织中分布却逐渐减少。 结论 MSC输注可促进大鼠IgA肾病的修复，其作用机制可能并不完全是依赖于MSC的直接分化，而是通过调节肾组织中细胞因子的分泌和（或）其他的功能进行修复。     

Over-expression of suppressor of cytokine signaling 3 inhibits the proliferation of human mesangial cells stimulated by aggregated IgA1 from IgA nephropathy patients

Objective To investigate the effect of suppressor of cytokine signaling 3 (SOCS3) on the proliferation of human mesangial cells stimulated by aggregated IgA1 (aIgA1) from patients with IgA nephropathy(IgAN), and explore its possible mechanism. Methods Serum monomeric IgA1 was isolated with jacalin affinity and Sephacryl S-200 HR chromatography from IgAN patients, and then heated to aggregated form (aIgA1). Human glomerular mesangial cells(HMC) were transfected with Adv-SOCS3-IRES2-EGFP for 48 hours, and incubated with aIgA1 for 12-48 h. The cells were divided into blank control group, IgA1 group, IgA1+Adv-EGFP group and IgA1+Adv-SOCS3-IRES2-EGFP group. The mesangial cell proliferation was observed through MTT, and the levels of SOCS3, TLR4, TGF-β1 protein and mRNA were detected through Western blotting and real-time PCR. Results HMC proliferation was promoted significantly after IgA1 stimulated at 24 h. Compared with control group, the protein and mRNA expression of SOCS3, TLR4, TGF-β1 were significantly increased in IgA1 group (P＜0.05). Compared with IgA1 group and IgA1+Adv-EGFP group, MTT absorbency was obviously reduced after incubation with aIgA1 for 24 h and 48 h in IgA+Adv-SOCS3-IRES2-EGFP group, and the protein and mRNA expression of TLR4 and TGF-β1 were significantly decreased in IgA1+Adv-SOCS3-EGFP group (P＜0.05). Conclusion Over-expression of SOCS3 may inhibit the proliferation of HMC stimulated by aIgA1, partly through down-regulating the expression of TLR4 and TGF-β1.     

Effect of aggregated immunoglobulin A1 from immunoglobulin A nephropathy patients on nephrin expression in podocytes

Aim: Abnormal immunoglobulin (Ig)A1 is considered to play a pivotal role in IgA nephropathy. We used mouse podocytes as the experimental model to investigate the effect of aggregated IgA1 (aIgA1) isolated from IgA nephropathy (IgAN) patients on nephrin expression in podocytes through direct and indirect pathways. Methods: Jacalin affinity chromatography and Sephacryl S‐200 molecular sieve chromatography were used to isolate IgA1 from blood of IgAN patients which was therefore became aIgA1. Podocytes were incubated with aIgA1 or special mesangial medium. Nephrin expression in podocytes was measured by real‐time polymerase chain reaction and western blot analysis. Results: Aggregated IgA1 from IgAN patients and healthy controls reduced nephrin expression in podocytes at mRNA and protein levels when compared with podocytes incubated with control medium (RPMI‐1640 with 0.5% foetal bovine serum) (P < 0.05). While medium from mesangial cells incubated with aIgA1 from IgAN inhibited nephrin expression in podocytes at mRNA and protein levels when compared with podocytes incubated with medium from mesangial cells with aIgA1 from healthy controls (P < 0.05). Conclusion: Our findings implicate that aIgA1 from IgAN patients could inhibit nephrin expression through direct and indirect pathways, although these mechanisms remain to be clarified.     

肾小管肝型脂肪酸结合蛋白对小鼠IgA肾病的肾脏保护作用

Objective To investigate the renoprotection of tubular L-FABP in murine IgA nephropathy (IgAN） induced by bone marrow transplantation(BMT). Methods IgAN models were reconstituted by BMT from IgAN-prone mice into mice (Tg) transgenically tubular overexpressing human L-FABP (hL-FABP) and wild type (WT) mice. These recipients were sacrificed at 6 and 12 weeks after BMT and their kidneys were collected. The expressions of hL-FABP, fibronectin (FN) and monocyte chemoattractant protein-1(MCP-1) mRNA were detected by real-time PCR. hL-FABP, FN, type Ⅳ collagen (Col Ⅳ), hemeoxygenase-1(HO-1) and 4-hydroxy-2-nonenal (4-HNE) modified proteins were detected by Western blotting. The distribution of hL-FABP and FN protein in kidney was detected by immunohistochemistry. The level of serum IgA, urinary albumin and urinary hL-FABP was detected by ELISA. Results (1) IgAN was reconstituted in both Tg and WT mice by BMT: mesangial IgA deposition and up-regulation of serum IgA. The levels were not significantly different between two groups (Tg-ddY and WT-ddY). (2) hL-FABP was expressed in proximal tubular cells of normal Tg mice. The mRNA (1.62±0.32 vs 0.46±0.09, P<0.01) and protein expression (1.74±0.76 vs 1.14±0.31, P<0.01) of hL-FABP was up-regulated in Tg-ddY kidney and urinary hL-FABP level (?滋g/g creatinine) was significantly increased (59.87±26.75 vs 31.01±14.86, P<0.05) at the 6th week after BMT. (3) WT-ddY mice showed a significantly higher urinary albumin level (mg/L) (828±656 vs 82±22, P<0.01), severer mesangial matrix expansion (P<0.01),more glomerular FN and Col Ⅳ deposition at the 12th week. (4) Up-regulation of renal hL-FABP was associated with significant suppression of renal HO-1 expression (P<0.05), accumulation of 4-HNE modified proteins (P<0.05) and MCP-1 mRNA expression (P<0.01) in Tg-ddY mice. Conclusion Tubular L-FABP may lessen the progression of glomerular damage at early stages of IgAN by reducing oxidative stress and inflammatory mediators.     

Differential effects of circulating IgA isolated from patients with IgA nephropathy on superoxide and fibronectin production of mesangial cells.

BACKGROUND: IgA nephropathy (IgAN) is characterized by predominant deposition of IgA in the glomerular mesangium. Serum IgA is often elevated in patients with IgAN, and it has been postulated that it is responsible for the mesangial lesions. However, the direct effect of circulating IgA on mesangial cells is not clear. METHODS: We investigated the effects of sera and IgA which were isolated from patients with IgAN on thymidine uptake, superoxide and fibronectin production and fibronectin mRNA expression of cultured rat mesangial cells, and we compared the findings to the effects of IgA isolated from patients with non-IgA mesangial proliferative glomerulonephritis (MsPGN) and normal controls. IgA was isolated with affinity chromatography using cyanogen bromide activated Sepharose 4B coupled to sheep antihuman IgA antiserum. RESULTS: Our results demonstrated that both sera and IgA from patients with IgAN dose-dependently increased mitogenesis of mesangial cells as measured by (3)H-labeled thymidine uptake. The thymidine uptake by sera and IgA isolated from patients with IgAN was significantly higher than that of sera and IgA isolated from patients with MsPGN and normal controls. Sera and IgA from patients with IgAN significantly enhanced superoxide and fibronectin production and fibronectin mRNA expression of mesangial cells. The superoxide and fibronectin production was also significantly higher as compared with patients with MsPGN and normal controls. CONCLUSIONS: Our results indicate that circulating IgA isolated from patients with IgAN is different from that of patients with MsPGN and normal controls and may potentially induce oxidative injury and production of extracellular matrix of glomerular mesangial cells in IgAN.     

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.     

胡桃夹综合征并发IgA肾病临床分析

目的 了解胡桃夹综合征并发IgA肾病的临床特点及提高其相应诊治水平。 方法 回顾分析14例胡桃夹综合征并发IgA肾病患者（病例组）及同期36例单纯胡桃夹综合征患者（对照组）的临床资料。所有胡桃夹综合征病例均由彩色多普勒超声和磁共振血管成像（MRA）诊断;IgA肾病均由病理证实。记录两组实验室、影像学资料并进行t检验分析。 结果 两组患者性别、年龄、血压差异无统计学意义。病例组Scr值高于对照组[（81.2±21.3） μmol/L比（61.2±11.8） μmol/L,P < 0.01],尿蛋白量较多[（1.1±0.6） g/d比（0.3±0.2） g/d,P < 0.01],血尿更明显（尿红细胞计分2.3±0.9比1.5±1.3,P < 0.05）。彩色多普勒超声显示两组左肾静脉狭窄处及近肾门处血流速度和内径差异无统计学意义;磁共振血管成像提示两组患者肠系膜上动脉与腹主动脉之间的夹角差异无统计学意义。 结论 对持续存在血尿和蛋白尿、异常红细胞比例较高的胡桃夹综合征患者应考虑存在并发慢性肾炎特别是IgA肾病的可能,应及早行肾活检明确诊断。     

Reduced binding of immunoglobulin A (IgA) from patients with primary IgA nephropathy to the myeloid IgA Fc-receptor, CD89

Background. Primary IgA nephropathy (IgAN) is associated with elevated levels of circulating IgA and is characterized by deposition of primarily IgA1 in the renal mesangium. It has not yet been clarified which mechanisms govern the deposition of IgA1 in the mesangium. One of the factors which may play a role in trapping of IgA in the mesangial area is the interaction of IgA with specific IgA receptors (Fc&agr;R, CD89) on the mesangial cells. Methods. In the present study IgA derived from patients with IgAN and controls was investigated for its interaction with human CD89, expressed on the surface of the murine B cell line IIA1.6. Results. IgA binding to Cd89 expressing cells was specific, concentration dependent and binding of dIgA and pIgA occurred in a more efficient fashion than that of mIgA. IgA binding to CD89 directly from serum of patients compared to controls showed no significant difference. However these experiments are affected by differences in IgA concentration and combinations of different sizes of IgA. Using purified fractions of mIgA, dIgA, and pIgA isolated from serum, a significantly reduced binding of mIgA to CD89 from patients compared to controls was observed. Finally, the binding of aIgA2 to CD89 was less inhibited using mIgA from patients with IgAN compared to controls. Conclusions. The reduced binding of mIgA to CD89 seems to contradict a direct role for CD89 in deposition of IgA. However reduced binding of mIgA to CD89 may affect IgA clearance, leading to higher serum IgA. Furthermore, since it has been demonstrated that mIgA can interfere with binding of di- and pIgA deposition in the mesangial area.