巨噬细胞衍生趋化因子在MRL/lpr小鼠肾组织中的异常表达

目的:研究巨噬细胞衍生趋化因子(MDC)在红斑狼疮小鼠狼疮肾炎中的作用。方法:比较MRL/lpr狼疮小鼠和BALB/c小鼠24h尿蛋白,并用逆转录-聚合酶链反应技术(RT-PCR)和免疫组织化学方法检测两组小鼠肾组织MDCmRNA及蛋白表达情况。结果:MRL/lpr小鼠24h尿蛋白高于BALB/c小鼠(P0.05);MRL/lpr小鼠肾组织MDCmRNA表达较BALB/c小鼠明显升高(P0.05);MRL/lpr小鼠肾小球、肾小管及间质均有明显MDC蛋白表达,而BALB/c小鼠肾脏未见MDC表达。结论:MDC在红斑狼疮小鼠肾脏组织中的表达增高,说明MDC可能参与介导了小鼠狼疮性肾炎的病变过程。     

MRL/lpr小鼠肾组织JAK/STAT信号转导途径的表达和雷帕霉素对其表达的影响

目的 探讨JAK／STAT1信号转导途径在MRL／lpr小鼠狼疮肾炎中所起的作用以及雷帕霉素对JAK／STAT1信号转导途径活化的影响。方法采用MRL／lpr转基因鼠，给予雷帕霉素干预治疗后，采用免疫组化方法研究肾脏磷酸化STAT1的组织分布情况，采用Westernblot方法研究磷酸化STAT1蛋白的表达，采用SYBRgreen嵌合荧光法real-time定量PCR研究SOCS-1mRNA的表达，从而研究STAT1的活化水平。结果MRL/lpr狼疮鼠肾脏的磷酸化STAT1蛋白明显活化，SOCS-1基因的表达升高，给予雷帕霉素治疗后肾脏的磷酸化STAT1蛋白表达降低，SOCS-1基因的表达降低。结论JAI（／STAT1信号转导途径的活化与狼疮肾炎的发病相关，雷帕霉素可以降低JAK／STAT1信号转导途径的表达．这可能是雷帕霉素治疗系统性红斑狼疮的机理之一。     

姜黄素对MRL/lpr狼疮鼠肾组织富含脯氨酸的酪氨酸激酶2信号转导途径表达的影响

目的 探讨富含脯氨酸的酪氨酸激酶2(PYK2)信号转导途径在MRL/lpr模型鼠狼疮肾炎中所起的作用以及姜黄素对PYK2信号转导途径活化的影响.方法 选用MRL/lpr转基因狼疮鼠为研究对象,给予姜黄素干预治疗后,采用免疫组化方法研究狼疮鼠肾脏磷酸化PYK2的组织分布情况,采用Western blot方法研究磷酸化PYK2蛋白的定量表达.结果 MRL/lpr狼疮鼠肾脏的磷酸化PYK2蛋白明显活化,给予姜黄素干预治疗后肾脏的磷酸化PYK2蛋白表达降低.结论 狼疮鼠肾脏PYK2信号转导途径的活化与狼疮肾炎的发病密切相关,姜黄素可以降低PYK2信号转导途径的表达.     

雷公藤多苷对单侧输尿管结扎小鼠肾小管间质纤维化和炎性损伤的影响

目的通过雷公藤多苷对UUO小鼠肾组织α-平滑肌肌动蛋白（α-smooth muscle actin,α-SMA）、细胞间黏附分子（Intercellular adhesion molecule1,ICAM-1）、单核细胞趋化因子（Monocyte chem oattractant protein1,MCP-1）表达的影响,探讨其防治肾间质纤维化作用及其机理。方法采用小鼠单侧输尿管结扎（UUO）模型,用雷公藤多苷进行干预,用血管紧张素受体抑制剂蒙诺作为对照。肾脏病理用HE和MASSON染色;肾组织α-SMA表达采用免疫组化;ICAM-1蛋白质表达采用Western blot方法检测;MCP-1基因表达采用逆转录-聚合酶链式反应（RT-PCR）方法。结果UUO模型组小鼠肾间质纤维化程度以及肾组织α-SMA的表达较假手术组显著增高,肾小管间质中炎细胞浸润亦较假手术组明显增加;雷公藤多苷各治疗组肾间质纤维化程度、α-SMA和ICAM-1蛋白、MCP-1基因表达均显著低于模型组;蒙诺治疗亦可显著降低肾间质纤维化程度和肾组织α-SMA的表达,但对于炎细胞浸润和炎症因子的抑制作用不如雷公藤多苷显著,而且未见其抑制ICAM-1表达的作用。结论雷公藤多苷可显著抑制肾间质纤维化和肌成纤维细胞的积聚,其机制可能与其抑制肾组织炎症因子的表达及炎细胞浸润有关。     

Fractalkine/CX3CR1在Ⅳ型狼疮肾炎患者肾组织中的表达

目的： 研究Ⅳ型弥漫增殖型狼疮肾炎、轻微性肾小球病变及正常肾组织中趋化因子fractalkine及其受体CX3CR1的表达，以及与CD68阳性巨噬细胞表达之间的相互关系，探讨fractalkine/CX3CR1在Ⅳ型狼疮肾炎发病中的作用。方法： Ⅳ型狼疮肾炎患者的肾活检组织21例，轻微性肾小球病变患者的肾活检组织18例，光镜下正常的肾组织标本8例。采用免疫组织化学技术检测肾组织中fractalkine、CX3CR1及CD68的表达。结果： （1）正常肾组织和轻微性肾小球病变肾组织中fractalkine基本未见阳性表达；其受体CX3CR1阳性细胞和CD68阳性巨噬细胞仅偶见于肾小球及肾皮质间质中。（2）Ⅳ型狼疮肾炎肾小球和肾皮质间质中CX3CR1阳性细胞和巨噬细胞显著增多，且两者的表达显示高度的相关性（分别为r=0.956，P＜0.01和r=0.965，P＜0.01）。（3）Ⅳ型狼疮肾炎肾组织中fractalkine高表达于皮质肾小管上，fractalkine 阳性皮质肾小管的百分比分别与肾皮质间质CX3CR1阳性细胞数和巨噬细胞数之间高度相关（分别为r=0.720，P＜0.01和r=0.770，P＜0.01）。结论： 提示fractalkine/CX3CR1在Ⅳ型狼疮肾炎的发病机制中可能占有重要地位。     

LTβR在MRL/lpr小鼠狼疮性肾炎病理发生中的作用及其机制初探

目的研究淋巴毒素β受体(lymphotoxinβreceptor,LTβR)在狼疮性肾炎病理发生中的作用及其机制。方法选取12周龄、雌性的MRL/lpr小鼠作为狼疮性肾炎小鼠模型,将其随机分为3组:生理盐水处理组、Human-Ig处理组和LTβR-Ig处理组,分别腹腔注射生理盐水(100μl),Human-Ig(100μg/只,100μl)和LTβR-Ig(100μg/只,100μl),每周1次,连续8周。同周龄和性别的C57BL/6小鼠为狼疮性肾炎模型小鼠的正常对照,每周腹腔注射生理盐水1次(100μl),连续8周。Human-Ig和LTβR-Ig处理组小鼠在首次处理后第2、4、6、8周称体质量。最后一次处理1周后,处死以上4组小鼠,收集肾组织。qRTPCR,IHC和Western blot比较C57BL/6小鼠和MRL/lpr小鼠肾组织中LTβR的表达情况。然后通过HE染色肾组织,qRT-PCR检测肾组织中LTβR、IL-6、MCP-1、TNF-α的表达水平;Western blot检测肾组织核转录因子κB(nuclear factor-kappa B,NF-κB)的活化情况,以C57BL/6小鼠肾组织作为正常对照,比较Human-Ig处理组和LTβR-Ig处理组小鼠(MRL/lpr小鼠)以上指标的变化。结果与C57BL/6小鼠相比,MRL/lpr小鼠肾组织中LTβR表达显著升高;与Human-Ig处理组相比,用LTβR阻断肽(LTβRIg)处理的MRL/lpr小鼠肾组织受损明显减轻,肾组织中炎症相关分子IL-6、MCP-1和TNF-α等的表达显著下降,NF-κB的活化明显下调。结论 LTβR可能通过促进狼疮性肾炎相关炎症因子的表达和NF-κB的活化,在狼疮性肾炎的病理发生中发挥重要作用。     

肾小管间质α-SMA表达与大鼠肾炎预后的关系

目的:了解肾毒血清肾炎大鼠肾小管间质α-平滑肌肌动蛋白(α-SMA)的表达与肾炎预后的关系及强的松治疗对其影响。方法:复制大鼠加速型肾毒血清肾炎(NTN)模型,随机分为非治疗和强的松治疗组,在肾炎第7、30、60和90d分别测定血清肌酐(Scr),尿蛋白(UP),肾小管间质形态和α-SMA的表达及分析相互关系。结果:肾小管间质α-SMA的表达与Scr,UP和肾小管间质病变相一致,强的松可抑制α-SMA的表达。结论:α-SMA的表达与肾炎病变的发展有密切关系,强的松影响α-SMA的表达,减少间质细胞的异化,在一定程度上改善肾炎的预后。     

三氧化二砷对MRL/lpr狼疮鼠T-bet/GATA3信号通路的影响

目的:本文旨在探讨三氧化二砷(arsenic trioxide,ATO)对MRL/lpr狼疮鼠T-bet/GATA3信号通路的影响及其作用机制。方法:将20周龄MRL/lpr狼疮鼠和正常C57BL/6J小鼠随机分组,分别接受ATO(0.4mg·kg~(-1)·d~(-1))和同体积生理盐水(NS)治疗2个月,分离脾脏淋巴细胞,然后用实时荧光定量PCR法检测T-bet、GATA3、IFN-γ、IL-4的mRNA水平及T-bet/GATA3 mRNA的比值,Western blot法检测T-bet和GATA3的蛋白表达,ELISA法检测血清中IFN-γ和IL-4的浓度。结果:(1)MRL/lpr狼疮鼠NS组T-bet、IFN-γ的mRNA及蛋白表达、Tbet/GATA3 mRNA比值均高于C57BL/6J小鼠NS组(P0.05),而GATA3、IL-4的mRNA及其蛋白表达均低于C57BL/6J小鼠NS组(P0.05);(2)在MRL/lpr狼疮鼠中,与NS组相比,ATO组T-bet、IFN-γ的mRNA及蛋白表达、T-bet/GATA3 mRNA比值均下降(P0.05),而2组中GATA3、IL-4的mRNA及蛋白表达无明显差异;(3)在C57BL/6J小鼠中,NS组和ATO组之间以上指标均无显著性差异。结论:ATO可能通过影响MRL/lpr狼疮鼠Tbet/GATA3信号通路,降低T-bet表达,从而减少Th1型细胞因子IFN-γ的表达和分泌。     

双氢青蒿素对狼疮模型MRL/lpr小鼠肾皮质Fractalkine表达的调节作用研究

目的通过研究双氢青蒿素(dihydroartemisinin,DHA)对狼疮模型MRL/lpr小鼠肾脏病变和肾皮质Fractalkine(FKN)、NF-κB表达的作用,并与泼尼松的作用进行比较,以探讨青蒿素治疗狼疮性肾炎的可能作用机制,试图明了双氢青蒿素对狼疮性肾炎FKN表达的调节作用。方法选取32只12周龄的雌性MRL/lpr小鼠,随机分为4组:DHA组,每天给予DHA灌胃;泼尼松组,每天给予泼尼松(prednisone,P)灌胃;DHA+泼尼松组,每天给予DHA和泼尼松灌胃;正常对照组,每天给予生理盐水灌胃;共8周。通过光镜观察肾组织病理改变,通过RT-PCR检测肾皮质FKN和NF-κB p65 mRNA的表达,免疫组织化学染色法检测肾皮质FKN及NF-κB p65蛋白的表达。结果 MRL/lpr小鼠肾皮质中检测到FKN、NF-κB p65 mRNA和蛋白的表达,DHA可减少MRL/lpr小鼠的蛋白尿、改善肾功能、减轻肾脏病变。DHA下调MRL/lpr小鼠肾皮质中FKN、NF-κB p65 mRNA和蛋白的表达。结论双氢青蒿素可通过调节FKN和NF-κB的表达实现其对狼疮性肾炎的治疗作用,与泼尼松联用效果更佳。     

蛋白酶体抑制剂MG132减轻糖尿病大鼠肾小管间质纤维化

目的探讨蛋白酶体抑制剂MG132是否减轻或延缓糖尿病肾病(DN)大鼠肾小管间质纤维化及其可能机制。方法用链脲菌素复制糖尿病大鼠模型(DM),实验分为对照组(NC)及DM组,每组n=10。24周处死大鼠,检测相应生化指标,观察肾组织病理改变;体外培养NRK-52E细胞,予以不同剂量MG132预处理后高糖培养。免疫组化、免疫荧光染色、Western blot检测肾组织和NRK-52E细胞中Smad7、Smurf2、E钙黏蛋白(E-cadherin)和α-平滑肌肌动蛋白(α-SMA)、纤维连接蛋白(FN)及胶原蛋白(Col-Ⅰ)的表达。结果与NC组相比,DM组大鼠肾组织E-cadherin减少(P0.05)、α-SMA增多(P0.05),FN及Col-Ⅰ蛋白在间质沉积增多(P0.05),而Smad7蛋白减少(P0.05),Smurf2表达增加(P0.05)。MG132抑制了高糖诱导的NRK-52E细胞α-SMA和Col-Ⅰ蛋白的表达(P0.05),并呈量效依赖性,但对Smurf2的蛋白表达无影响;相反,MG132上调了Smad7蛋白及E-cadherin的表达(P0.05)。结论 MG132减缓糖尿病大鼠肾小管间质纤维化。     

STAT1的SUMO4修饰在高糖诱导的肾小管上皮细胞上皮-间叶性转化中的作用

目的探讨STAT1的SUMO4修饰与人近端肾小管上皮细胞(HK-2)表型转化的关系。方法将HK-2细胞分为空白对照组(NG,5.5 mmol/L葡萄糖)、高糖组(HG,30 mmol/L葡萄糖)、SUMO4-siRNA(转染SUMO4 siRNA)组、NC-siRNA(转染scrimble siRNA)组、UBC9-siRNA(转染UBC9 siRNA)组。采用免疫细胞化学、Western blot法检测E-cadherin、α-SMA、vimentin等的表达;双荧光素酶报告基因分析检测STAT1的转录活性;免疫共沉淀检测STAT1的SUMO4修饰。结果高糖刺激后,HK-2细胞中E-cadherin表达降低,而vimentin与α-SMA表达增高(P<0.05);高糖上调STAT1的SUMO4修饰;不论是SUMO4 siRNA转染还是UBC9 siRNA转染,均能显著提升STAT1的活性(P<0.01);同时SUMO4 siRNA转染可部分逆转高糖导致的E-cadherin和α-SMA表达变化(P<0.05)。结论抑制STAT1的SUMO4修饰增加STAT1的活性,缓解了高糖诱导的HK-2细胞的上皮-间叶性转化。     

黄芪多糖对糖尿病肾病肾小管上皮细胞凋亡、转分化及ROS 含量的影响研究

目的:探讨黄芪多糖对糖尿病肾病肾小管上皮细胞凋亡、转分化及ROS 含量的影响。方法:HK-2 细胞分为低糖组、高糖组和黄芪多糖+高糖组,处理细胞48 h 后,CCK-8 实验检测细胞增殖;流式细胞仪检测细胞凋亡及ROS 含量;Western blot 检测E-cadherin、α-SMA、STAT1、STAT3、p-STAT1、p-STAT3 蛋白表达。结果:高糖组细胞存活率显著低于低糖组(P<0.01),细胞凋亡率、ROS 含量及E-cadherin、α-SMA、p-STAT1、p-STAT3 蛋白表达均显著高于低糖组(P<0.01),高糖+黄芪多糖组细胞存活率显著高于高糖组,细胞凋亡率、ROS 含量及E-cadherin、α-SMA、p-STAT1、p-STAT3 蛋白表达均显著低于高糖组(P<0.01)。结论:黄芪多糖可促进高糖诱导的肾小管上皮细胞增殖,抑制细胞凋亡及转分化,其机制与下调JAK/ STAT 信号通路有关。     

The role of Stim1 in the progression of lupus nephritis in mice

Objective: To investigate the expression of Stim1 in the kidneys of mice with lupus, and the effect of Stim1 on the progression of renal interstitial fibrosis. Methods: Mice (MRL/lpr) with spontaneous lupus nephritis (LN) and normal control mice (C57/BL) were selected. Immunohistochemistry and Masson staining were used to determine the degree of renal interstitial fibrosis in kidney tissues. The expression of Stim1 and fibronectin in tissues was measured by qRT-PCR, western blotting, and immunohistochemistry. Urine protein, blood urea nitrogen, and serum creatinine levels in the mice were analyzed, and Spearman analysis was conducted to determine the correlation with Stim1 expression levels. Mouse renal tubular epithelial cells (mRTECs) were chosen as the experimental objects. After various treatments, the cells were divided into the blank control group, lipopolysaccharide (LPS) treatment group, LPS+siRNA-NC group and LPS+siRNA-Stim1 group. Western blotting and immunofluorescence were used to measure epithelial-mesenchymal transition (EMT)-related protein levels. Results: There was significant interstitial fibrosis in the kidneys of LN mice. Compared with that in normal mice, the expression of Stim1 in the kidney tissues of LN mice was significantly increased, and Stim1 expression was positively correlated with fibronectin, urine protein, blood urea nitrogen and serum creatinine levels. LPS induced the expression of Stim1, fibronectin, and α-SMA in mRTECs and decreased the protein level of E-CA, while silencing Stim1 effectively alleviated the effects of LPS. Conclusion: Stim1 is significantly increased in the kidneys of lupus mice, and it is possible to promote EMT in renal tubular epithelial cells and renal interstitial fibrosis by elevating fibronectin, which ultimately contributes to renal damage.     

Differential roles of ICAM-1 and VCAM-1 in leukocyte-endothelial cell interactions in skin and brain of MRL/faslpr mice

MRL/fas(lpr) mice, which undergo a systemic autoimmune disease with similarities to systemic lupus erythematosus (SLE), display reduced pathology and prolonged survival if rendered deficient in ICAM-1. However, it remains unclear whether this is a result of the ability of ICAM-1 to promote the immune response or mediate leukocyte recruitment. Therefore, the aim of these studies was to compare the role of ICAM-1 in the elevated leukocyte-endothelial interactions, which affect MRL/fas(lpr) mice. Intravital microscopy was used to compare leukocyte rolling and adhesion in postcapillary venules in the dermal and cerebral (pial) microcirculations of wild-type (ICAM+/+) and ICAM-1-deficient (ICAM-1-/-) MRL/fas(lpr) mice. In the dermal microcirculation of 16-week MRL/fas(lpr) mice, leukocyte adhesion was increased relative to nondiseased MRL+/+ mice. However, this increase was abolished in ICAM-1-/- MRL/fas(lpr) mice. ICAM-1 deficiency was also associated with reduced dermal pathology. In contrast, in the pial microcirculation, the elevation in leukocyte adhesion observed in ICAM+/+ MRL/fas(lpr) mice also occurred in ICAM-1-/- MRL/fas(lpr) mice. VCAM-1 expression was detectable in both vascular beds, but higher levels were detected in the pial vasculature. Furthermore, VCAM-1 blockade significantly reduced leukocyte adhesion and rolling in the cerebral microcirculation of ICAM-1-/- MRL/fas(lpr) mice. Therefore, ICAM-1 was critical for leukocyte adhesion in the skin but not the brain, where VCAM-1 assumed the major function. Given the ongoing development of anti-adhesion molecule therapies and their potential in inflammatory diseases such as SLE, these data indicate that implementation of these therapies in SLE should take into account the potential for tissue-specific functions of adhesion molecules.     

High expression of interleukin-1beta in the corneal epithelium of MRL/lpr mice is under the control of their genetic background

MRL/Mp mice bearing the Fas deletion mutant gene, lpr (MRL/lpr), spontaneously develop polyarthritis, sialoadenitis and dacryoadenitis, resembling rheumatoid arthritis (RA), and also corneal involvement such as keratopathy and scleritis, which is a major complication in RA patients. In this study, we found that the expression levels of IL-1beta and MMP-1 mRNAs in cornea were high in both MRL/lpr and MRL/Mp-+/+ strains of mice at an age younger than when they develop any inflammatory lesions. This was not true of other inbred strains, even those bearing the lpr gene, and also not of (NZB x NZW) F1 lupus mice. There was no significant difference in the expression of IL-1alpha and TGFbeta in cornea in these strains. Using crosses between MRL/lpr and C3H/HeJ-lpr/lpr (C3H/lpr) mice, at least the expression of IL-1beta was found to be under the control of the MRL genetic background, likely with a recessive mode of inheritance. Considering that IL-1beta in cornea was detected particularly in the epithelial layer, the high expression of IL-1beta in cornea is most likely involved in the genetic predisposition for corneal involvement and possibly also for arthritis in an MRL strain of mice.     

白细胞介素17 在狼疮性肾炎小鼠中的表达及抗白细胞介素17抗体的干预作用

 目的:探讨白细胞介素17（IL-17）在狼疮性肾炎(LN）小鼠中的表达及抗IL-17抗体的干预作用。方法:11周龄的雌性MRL/lpr小鼠36只随机分为实验组和干预组,另有同龄雌性昆明小鼠18只为对照组。干预组每只小鼠腹腔注射抗小鼠IL-17多克隆抗体20 μg,每2周1次,至实验观察点结束。各组分别于第1次给药后的24 h、14 d及28 d处死6只小鼠。光镜下观察肾脏病理情况,ELISA法检测小鼠血清IL-17的含量,免疫组化法检测肾组织IL-17的表达水平。结果:MRL/lpr小鼠肾小球系膜细胞及基质弥漫增生,肾小管上皮细胞颗粒及空泡变性,灶状萎缩,肾间质淋巴及单核细胞浸润伴纤维化;而干预组肾脏病理改变较实验组为轻。MRL/lpr小鼠的血清IL-17含量在实验组各时点均显著高于对照组（P<0.05）,而在干预组各时点均显著低于实验组（P<0.05）。IL-17在实验组小鼠肾小管上皮细胞中的表达明显增强,在各时点均显著高于对照组（P<0.05）;在干预组,IL-17在各时点的表达均显著低于实验组（P<0.05）。结论:IL-17在MRL/lpr小鼠血清与肾组织中的表达显著增加,而抗IL-17抗体可通过抑制IL-17的表达而抑制LN的炎症免疫反应,减轻肾脏病理损害。     

糖尿病大鼠肾组织中miR-21和SnoN表达的变化

目的探讨糖尿病(DM)大鼠肾组织中微小核糖核酸-21(miR-21)和核转录共抑制因子(SnoN)在肾纤维化过程中的表达变化及其可能机制。方法用链脲佐菌素复制DM大鼠模型,并设对照组(NC),每组n=8。10周后处死大鼠,观察肾组织形态变化;免疫组织化学染色、Western blot及RT-q PCR检测miR-21、SnoN、转化生长因子-β1(TGF-β1)、Smad3、p-Smad3(Ser423/425)、E钙黏蛋白(E-cadherin)、α-平滑肌肌动蛋白(α-SMA)、纤维连接蛋白(FN)、胶原蛋白Ⅰ(collagenⅠ)和胶原蛋白Ⅲ(collagenⅢ)的表达。结果与对照组相比,DM组肾组织p-Smad3(Ser423/425)、TGF-β1和α-SMA蛋白表达增加(P0.05),SnoN、E-cadherin蛋白表达减少(P0.05),但SnoN mRNA和miR-21表达明显上调(P0.05),并伴有collagenⅠ、collagenⅢ和FN在间质沉积增多。结论 TGF-β1可能上调miR-21表达,抑制SnoN翻译水平的表达,促进DN的纤维化病变。     

Enhanced MHC class II expression in renal proximal tubules precedes loss of renal function in MRL/lpr mice with lupus nephritis

Enhanced MHC class II (Ia) antigen expression is a common feature of autoimmunity. The authors investigated the occurrence of renal Ia expression in MRL/MpJ-lpr/lpr (MRL/lpr) mice with lupus nephritis. By immunoperoxidase staining, normal C3H/FeJ and the congenic strain MRL/MpJ-+/+ express Ia in mononuclear cells in the interstitium only, whereas MRL/lpr with nephritis have abundant Ia expression in proximal tubules (PT), mainly towards the basolateral membrane, and in the characteristic perivascular infiltrates. To a lesser extent, enhanced Ia expression is also observed in the interstitium and in the glomerular mesangium. By Northern blot analysis, the increase in Ia surface determinants correlates with an increased steady-state level of class II mRNA for both I-A and I-E. Ia expression on PT starts focally at around 2-months of age, often in proximity to vascular infiltrates, and precedes overt glomerulo-nephritis and proteinuria. Enhanced class II expression is not restricted to the kidney. MRL/lpr have also increased interstitial class II antigen expression in liver, lung, and spleen compared with normal C3H/FeJ mice. Thus, MRL/lpr mice have enhanced systemic Ia expression, but Ia antigen expression is particularly prominent in PT and may play a key role in the initiation and progression of lupus nephritis.