Abstract
Autoantibodies against C1q are strongly linked to immune-complex disorders like systemic lupus erythematosus (SLE). Although anti-C1q antibodies have received much interest in the recent years, their biological functions remain unclear. Anti-C1q antibodies are strongly associated with lupus nephritis. The aim of this study was to determine the prevalence of anti-C1q antibodies in Egyptian lupus patients as well as to evaluate the associations between anti C1q antibodies and clinical and serologic parameters of patients with cutaneous and systemic lupus erythematosus.Fifty-eight patients of lupus erythematosus were recruited in the study, and they were divided into 3 groups according to their clinical presentations and laboratory investigations; group (1) consists of 20 patients with musculoskeletal manifestations, mainly arthritis (34.5%), group (2) consists of 12 patients with lupus nephritis (20%), and group (3) consists of 26 patients with cutaneous lupus (44.8%). Fourteen age and sex matched healthy subjects served as controls. Complete blood picture, kidney function tests, liver function tests and anti-double stranded DNA were done for all the studied patients. Anti-C1q antibodies were determined by immunometric enzyme immunoassay for all the studied subjects.Anti-C1q antibodies were positive in (63.8%) of lupus erythematosus (LE) patients and (0%) of controls. Moreover, the serum anti-C1q antibodies titers were significantly higher (P<0.001) in all lupus erythematosus patients (both systemic and cutaneous) when compared to healthy controls. Surprisingly, serum anti-C1q antibodies were significantly higher in patients with cutaneous lupus than those with lupus nephritis (P<0.001). Anti-C1q titers were significantly correlated with levels of anti–double stranded DNA (P<0.001), as well as with proteinuria (<0.05) in lupus nephritis patients.It was concluded that anti C1q antibodies might play a pathogenic role in the pathogenesis of cutaneous lupus and could positively be associated with evolution to SLE. Moreover, it could predict patients who subsequently develop nephritis, thus early use of immune modulators in cutaneous lupus could improve patients’ prognosis by decreasing the possibility of evolution to systemic lupus complications, mainly nephritis.
Highlights
Systemic Lupus erythematosus (SLE) is an autoimmune disease characterized by a broad clinical spectrum from cutaneous lesions to severe systemic manifestation
Anti-C1q antibodies were significantly correlated with proteinuria in lupus nephritis patients, but not with serum creatinine, serum albumin, erythrocyte sedimentation rate (ESR), hemoglobin, leucocytes or platelets (Table 3)
In the present study it was observed that there was significant relation between serum anti-C1q antibodies and proteinuria in lupus nephritis patients, on the other hand there was no correlation between anti-C1q antibodies and serum creatinine, serum albumin, complete blood picture parameters as well as ESR
Summary
Systemic Lupus erythematosus (SLE) is an autoimmune disease characterized by a broad clinical spectrum from cutaneous lesions to severe systemic manifestation. Anti-C1q antibodies were observed in 100% of patients with hypocomplementemic urticarial vasculitis and in 30–48% of patients with SLE [5,6] They were strongly linked to other immune-complex disorders such as rheumatoid vasculitis and rheumatoid arthritis [1]. The SLE, as an autoimmune disease, is certainly related to disorders caused by the activation of a complement system that leads to tissue damage [7]. The hereditary deficiency (complement genes mutations) of this component; C1q; is a known risk factor for the development of SLE [3]. Anti-C1q antibodies have received much interest in the recent years, their biological functions remain unclear Their high negative predictive value for active lupus nephritis suggests a pathogenic role in SLE patients. Clearance of anti C1q antibodies by repeated plasmapheresis or C1q immunoabsorption improved the clinical status of SLE patients [9,10]
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