THE MECHANISM OF NEPHRITOGENIC ANTI-DNA ANTIBODY PRODUCTION IN LUPUS NEPHRITIS

本研究的目的是阐明人类肾炎性抗DNA抗体产生的抗原触发因素。我们发现人的单抗O-81抗DNA抗体可与内质网应激诱导蛋白Herp1结合。分别用DNA固定化琼脂糖凝胶和Herp固定化琼脂糖凝胶从活动期狼疮性肾炎患者体内获得抗DNA抗体和抗Herp抗体。与疱疹病毒结合的狼疮抗DNA抗体。此外，抗疱疹病毒抗体与DNA具有特异性结合。每只6周龄BALB/c雌性小鼠分别用疱疹病毒或鸡蛋溶菌酶(HEL)进行免疫。用Herp免疫BALB/c小鼠，而不用HEL免疫，可诱导BALB/c小鼠产生抗dsDNA和抗ssDNA抗体，并在肾小球形成免疫球蛋白。用抗疱疹病毒的单抗对SLE患者和正常人的PBL进行染色。HERP在活动期SLE患者的PBL中自发表达，而在正常人的PBL中表达。体外培养72小时后，观察HELP在SLE PBL中的表达。正常外周血中未见HELP的表达。为评价Herp的抗原性，将PBL与Herp共同培养6d，用ELISPOT法检测产生抗DNA抗体的克隆数。活动期SLE患者PBL经Herp刺激后，体外产生抗DNA抗体的克隆数增加，而HEL或dsDNA刺激后无明显变化。来自非活动期SLE患者或健康受试者的PBL对Herer的刺激没有反应。这些结果表明，一种可诱导的细胞内自身蛋白可能是人类肾炎性抗DNA自身抗体的触发因素，其中可能存在内质网应激。

The aim of the present study is to elucidate the antigenic trigger for the production of human nephritogenic anti-DNA antibodies. We found that a human monoclonal nephritogenic O-81 anti-DNA antibody bound to an endoplasmic reticulum stress-inducible protein, Herp.1. The anti-DNA or anti-Herp antibodies were obtained from the patients with active lupus nephritis by using a DNA-immobilized or a Herp-immobilized agarose, respectively. Lupus anti-DNA antibodies bound to Herp. Moreover, the anti-Herp antibodies showed specific binding to DNA.2. Each 6-week-old BALB/c female mouse was immunized intraperitoneally with Herp or Hen Egg Lysozyme (HEL). immunization with Herp, but not HEL, elicited anti-dsDNA as well as anti-ssDNA antibodies in BALB/c mice and formed the deposits of IgG in the renal glomeruli.3. The PBLs from SLE patients or healthy subjects were stained with a monoclonal anti-Herp antibody. Herp was spontaneously expressed in the PBLs of patients with active SLE, but in the PBLs of healthy subjects. The expression of Herp in the SLE PBLs was observed during the 72 hours in vitro culture without any stimulation. No expression of Herp was observed in healthy PBLs.4. To assess the antigenicity of Herp, the PBLs were cultured with Herp for 6 days, and the number of anti-DNA antibody producing clones was measured by ELISPOT assay. The number of anti-DNA antibody producing clones in the PBLs from active SLE patients increased in vitro after stimulation with Herp, but not with HEL or dsDNA. The PBLs form inactive SLE patients or healthy subjects did not respond to the stimulation with Herp.These results imply that an inducible intracellular self protein could be a trigger for human nephritogenic anti-DNA autoantibodies, where ER stress may be noted.