BACKGROUND C3 hypocomplementemia and the presence of C3 nephritic factor (C3NeF), an autoantibody causing complement system over-activation, are common features among most patients affected by Barraquer-Simons syndrome (BSS), an acquired form of partial lipodystrophy. Moreover, BSS is frequently associated with autoimmune diseases. However, the relationship between complement system dysregulation and BSS remains to be fully elucidated. The aim of this study was to provide a comprehensive immunological analysis of the complement system status, autoantibody signatures and HLA profile in BSS. Thirteen subjects with BSS were recruited for the study. The circulating levels of complement components, C3, C4, Factor B (FB) and Properdin (P), as well as an extended autoantibody profile including autoantibodies targeting complement components and regulators were assessed in serum. Additionally, HLA genotyping was carried out using DNA extracted from peripheral blood mononuclear cells. RESULTS C3, C4 and FB levels were significantly reduced in patients with BSS as compared with healthy subjects. C3NeF was the most frequently found autoantibody (69.2% of cases), followed by anti-C3 (38.5%), and anti-P and anti-FB (30.8% each). Clinical data showed high prevalence of autoimmune diseases (38.5%), the majority of patients (61.5%) being positive for at least one of the autoantibodies tested. The HLA allele DRB1*11 was present in 54% of BSS patients, and the majority of them (31%) were positive for *11:03 (vs 1.3% in the general population). CONCLUSIONS Our results confirmed the association between BSS, autoimmunity and C3 hypocomplementemia. Moreover, the finding of autoantibodies targeting complement system proteins points to complement dysregulation as a central pathological event in the development of BSS.

中文翻译：

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受Barraquer-Simons综合征影响的患者的免疫学特征。

背景C3补体不足和C3肾炎因子（C3NeF）（一种导致补体系统过度激活的自身抗体）的存在是受Barraquer-Simons综合征（BSS）（一种部分性脂肪营养不良的获得形式）影响的大多数患者的共同特征。此外，BSS通常与自身免疫性疾病相关。然而，补体系统失调与BSS之间的关系仍有待充分阐明。这项研究的目的是提供对BSS中补体系统状态，自身抗体特征和HLA谱的全面免疫学分析。招募了13名BSS受试者进行研究。补体成分C3，C4，因子B（FB）和备解素（P）的循环水平 以及在血清中评估了扩展的自身抗体谱，包括针对补体成分和调节剂的自身抗体。另外，使用从外周血单核细胞提取的DNA进行HLA基因分型。结果与健康受试者相比，BSS患者的C3，C4和FB水平显着降低。C3NeF是最常见的自身抗体（占病例的69.2％），其次是抗C3（占38.5％），抗P和抗FB（各占30.8％）。临床数据显示，自身免疫性疾病的患病率很高（38.5％），大多数患者（61.5％）的至少一种自身抗体呈阳性。HLA等位基因DRB1 * 11存在于54％的BSS患者中，其中大多数（31％）的* 11：03呈阳性（与普通人群的1.3％相比）。结论我们的结果证实了BSS，自身免疫和C3低补体血症之间的关联。此外，针对补体系统蛋白的自身抗体的发现表明补体失调是BSS发生中的主要病理事件。