Volume 65, Issue 11 pp. 2963-2970
Behçet's Syndrome

Copy Number Variations of Complement Component C4 Are Associated With Behçet's Disease but Not With Ankylosing Spondylitis Associated With Acute Anterior Uveitis

Shengping Hou

Shengping Hou

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

Search for more papers by this author
Jian Qi

Jian Qi

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

Search for more papers by this author
Dan Liao

Dan Liao

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

Search for more papers by this author
Qi Zhang

Qi Zhang

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

Search for more papers by this author
Jing Fang

Jing Fang

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

Search for more papers by this author
Yan Zhou

Yan Zhou

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

Search for more papers by this author
Yunjia Liu

Yunjia Liu

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

Search for more papers by this author
Lin Bai

Lin Bai

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

Search for more papers by this author
Meifen Zhang

Meifen Zhang

Peking Union Medical College Hospital and Chinese Academy of Medical Sciences, Beijing, China

Search for more papers by this author
Aize Kijlstra

Aize Kijlstra

University Eye Clinic Maastricht, Maastricht, Limburg, The Netherlands

Search for more papers by this author
Peizeng Yang

Corresponding Author

Peizeng Yang

The First Affiliated Hospital of Chongqing Medical University, Chongqing Eye Institute, and Chongqing Key Laboratory of Ophthalmology, Chongqing, China

The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing 400016, China. E-mail: [email protected]Search for more papers by this author
First published: 05 August 2013
Citations: 32

Abstract

Objective

Complement component C4 copy number variations are associated with various inflammatory diseases. This study was undertaken to investigate whether copy number variations of C4 are also involved in the pathogenesis of Behçet's disease (BD).

Methods

Gene expression was examined by enzyme-linked immunosorbent assay (ELISA) or real-time polymerase chain reaction (PCR). Copy number variations of C4 isotypes (C4A and C4B) were detected by real-time PCR in 905 patients with BD, 205 patients with ankylosing spondylitis (AS) and acute anterior uveitis, and 1,238 controls. The activation of CD4+ T cells was analyzed by flow cytometry, and cytokine production was detected by ELISA.

Results

Protein expression of total C4 in serum was significantly increased in patients with active BD compared with those with inactive BD or controls (Bonferroni corrected P [Pcorr] = 1.64 × 10−4 and Pcorr = 0.037, respectively), but not in patients with AS and acute anterior uveitis. Copy number variation analysis identified a significantly increased frequency of more than 2 copies of C4A in BD patients (P = 1.65 × 10−7, odds ratio [OR] 2.84). HLA–B51, which is located on the same chromosome as C4, showed a strong association with BD in the Han Chinese population (P = 8.90 × 10−65, OR 5.05), but logistic regression showed that C4A copy number variation was an independent risk factor for BD. A significantly increased expression of C4A was observed in the high copy number groups (>2 copies or 2 copies) versus the low copy number group (Pcorr = 0.019 and Pcorr = 0.044, respectively). Increased production of interleukin-6 (IL-6) was also observed in the high C4A copy number group (Pcorr = 0.037). No effect of C4 copy number variation on the expression of T cell activation markers was detected.

Conclusion

Our findings indicate that a high copy number of C4A confers risk for BD by modulating the expression of C4A and enhancing IL-6 production.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.

click me