ANTI-C1q IN SYSTEMIC LUPUS ERYTHEMATOSUS: RELATIONSHIP WITH CLINICAL MANIFESTATIONS AND DISEASE ACTIVITY

Abstract

Objective: Lupus nephritis (LN) is a detrimental consequence of systemic lupus erythematosus (SLE). The anti-C1q antibody was shown to be related to LN, or global disease activity, in various studies. Our purpose was to determine its prevalence and association with LN or disease activity in Turkish patients with SLE. Material and Method: We conducted a cross-sectional single-centre study to investigate the clinical and laboratory findings, disease activity, and anti-C1q levels in 150 patients with SLE. The anti-C1q antibody was analyzed using an enzyme-linked immunosorbent assay and compared with 150 healthy-control patients. Result: Lupus nephritis was present in 72 patients. The frequency of anti-C1q positivity was 17% (26/150) in patients with SLE and 3% (5/150) in control group (p<0.001). Patients with anti-C1q also had anti-Sm, direct Coombs’ test, and thrombocytopenia more commonly (p=0.001, p=0.007, p=0.009 respectively). Anti-C1q was positively correlated with proteinuria, haematuria, systemic lupus erythematosus disease activity index (SLEDAI) (p<0.001), anti-dsDNA (p=0.03), and negatively correlated with C3 (p<0.001) and C4 (p=0.015). Patients with active LN had higher anti-C1q (p=0.01) and anti-dsDNA (p<0.001) titres than inactive LN patients, although in multivariate logistic regression analysis, anti-C1q was not significant for LN history. It was significant for SLEDAI severity (p=0.036). Conclusion: Our study demonstrated a significant association of anti-C1q with SLE, proteinuria, haematuria, thrombocytopenia, general disease activity, and active LN, but not with inactive renal disease. This is the first study investigating the clinical significance of this antibody in Turkish patients. Further studies are needed to clarify the pathogenesis of lupus nephritis.

Keywords

• Anti-C1q
• systemic lupus erythematosus
• lupus nephritis
• systemic lupus erythematosus disease activity index

SİSTEMİK LUPUS ERİTEMATOZUSTA ANTİ-C1q: KLİNİK BULGULAR VE HASTALIK AKTİVİTESİ İLE İLİŞKİSİ

Abstract

Amaç: Lupus nefriti (LN), sistemik lupus eritematozus'un (SLE) tehlikeli bir sonucudur. Çeşitli çalışmalarda anti-C1q antikorunun LN veya global hastalık aktivitesi ile ilişkili olduğu gösterilmiştir. Bu çalışmada amacımız, Türk SLE’li hastalarda anti-C1q prevalansını, LN veya hastalık aktivitesi ile ilişkisini belirlemekti. Gereç ve Yöntem: Kesitsel tek merkezli bir çalışma ile 150 SLE’li hastada klinik ve laboratuvar bulguları, hastalık aktivitesi ve anti-C1q düzeyleri değerlendirildi. Anti-C1q antikoru, ELISA (enzyme-linked immunosorbent assay) ile analiz edildi, toplam 150 kişiden oluşan hasta ve sağlıklı kontrol grubu ile karşılaştırıldı. Bulgular: Yetmiş iki hastada LN’i saptandı. Anti-C1q pozitiflik oranı SLE hastalarında %17 (26/150), kontrol grubunda ise %3 (5/150) idi (p<0,001). Anti-C1q antikoru pozitif olan hastalarda aynı zamanda pozitif anti-Sm antikoru, direkt Coombs testi ve trombositopeni de daha sık görüldü (sırasıyla p=0,001, p=0,007, p=0,009). Anti-C1q antikoru proteinüri, hematüri, sistemik lupus eritematoz hastalık aktivite indeksi (SLEDAI) (p<0,001), anti-dsDNA (p=0,03) ile pozitif, C3 (p<0,001) ve C4 (p=0,015) ile negatif korelasyon gösterdi. Aktif LN'li hastalarda anti-C1q (p=0,01) ve anti-dsDNA (p<0,001) titreleri inaktif LN hastalarına göre daha yüksekti, ancak çok değişkenli lojistik regresyon analizinde anti-C1q LN öyküsü için anlamlı değildi. SLEDAI şiddeti açısından anlamlılık saptandı (p=0,036). Sonuç: Çalışmamız anti-C1q antikorunun SLE, proteinüri, hematüri, trombositopeni, genel hastalık aktivitesi ve aktif LN ile anlamlı bir ilişkisi olduğunu, ancak inaktif böbrek hastalığı ile ilişkili olmadığını kanıtladı. Çalışmamız, bu antikorun Türk SLE’li hastalarda klinik önemini araştıran ilk araştırmadır. Lupus nefritinin patogenezini açıklığa kavuşturmak için daha ileri çalışmalara ihtiyaç vardır.

Keywords

• Anti-C1q
• lupus nefriti
• sistemik lupus eritematozus
• sistemik lupus eritematozus hastalık aktivite indeksi

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