[Correlation of anti-C1q antibodies with active systemic lupus erythematosus and lupus nephritis in children]. / 抗C1qæŠ—ä½“ä¸Žå„¿ç«¥æ´»åŠ¨æ€§ç³»ç»Ÿæ€§çº¢æ–‘ç‹¼ç–®å’Œæ´»åŠ¨æ€§ç‹¼ç–®æ€§è‚¾ç‚Žçš„ç›¸å ³æ€§åˆ†æž.

OBJECTIVES: To study the correlation of anti-C1q antibodies with active systemic lupus erythematosus (SLE) and lupus nephritis (LN) in children, as well as their diagnostic value for active SLE and LN. METHODS: A retrospective selection of 90 hospitalized children with SLE at the Children's Medical Center of Second Xiangya Hospital, Central South University from January 2016 to March 2019 as the SLE group, all of whom were tested for anti-C1q antibodies. A control group was formed by collecting 70 hospitalized children with other autoimmune diseases (OAD) during the same period. The differences in anti-C1q antibody levels were compared between two groups.The correlation of anti-C1q antibodies with various indicators of SLE and LN was analyzed, and the diagnostic value of anti-C1q in SLE and LN was evaluated. RESULTS: The serum levels of anti-C1q antibodies in the SLE group were higher than those in the OAD group (P<0.05). The SLE disease activity index score was positively correlated with anti-C1q antibodies (rs=0.371, P<0.001) and positively correlated with anti-double-stranded DNA antibodies (rs=0.370, P<0.001). The sensitivity and specificity of anti-C1q antibodies for diagnosing active SLE were 89.90% and 53.90%, respectively, with an area under the curve of 0.720 (P<0.05) and a critical value of 5.45 U/mL. The sensitivity and specificity of anti-C1q antibody levels for diagnosing active LN were 58.50% and 85.00%, respectively, with an area under the curve of 0.675 (P<0.05) and a critical value of 22.05 U/mL. CONCLUSIONS: Anti-C1q antibodies can serve as non-invasive biomarkers for evaluating the activity of SLE or predicting the activity of LN in children.

Biopsy-proven kidney involvement in hypocomplementemic urticarial vasculitis.

BACKGROUND: Hypocomplementemic urticarial vasculitis (HUV) is a rare systemic vasculitis. We aimed to describe the kidney involvement of HUV in a multicenter national cohort with an extended follow-up. METHODS: All patients with HUV (international Schwartz criteria) with a biopsy-proven kidney involvement, identified through a survey of the French Vasculitis Study Group (FVSG), were included. A systematic literature review on kidney involvement of HUV was performed. RESULTS: Twelve patients were included, among whom 8 had positive anti-C1q antibodies. All presented with proteinuria, from mild to nephrotic, and 8 displayed acute kidney injury (AKI), requiring temporary haemodialysis in 2. Kidney biopsy showed membrano-proliferative glomerulonephritis (MPGN) in 8 patients, pauci-immune crescentic GN or necrotizing vasculitis in 3 patients (with a mild to severe interstitial inflammation), and an isolated interstitial nephritis in 1 patient. C1q deposits were observed in the glomeruli (n = 6), tubules (n = 4) or renal arterioles (n = 3) of 8 patients. All patients received corticosteroids, and 9 were also treated with immunosuppressants or apheresis. After a mean follow-up of 8.9 years, 6 patients had a preserved renal function, but 2 patients had developed stage 3-4 chronic kidney disease (CKD) and 4 patients had reached end-stage kidney disease (ESKD), among whom 1 had received a kidney transplant. CONCLUSION: Renal involvement of HUV can be responsible for severe AKI, CKD and ESRD. It is not always associated with circulating anti-C1q antibodies. Kidney biopsy shows mostly MPGN or crescentic GN, with frequent C1q deposits in the glomeruli, tubules or arterioles.

High frequency of concurrent anti-C1q and anti-dsDNA but not anti-C3b antibodies in patients with Lupus Nephritis.

Lupus Nephritis (LN) in patients with Systemic Lupus Erythematosus (SLE) is one of the most serious and prevalent manifestations. The procedure of renal biopsy is harmful and accompanied by potential hazards. Therefore, introducing reliable biomarkers to predict LN is exceedingly worthwhile. In the present study, we compared the diagnostic values of circulating autoantibodies against dsDNA, C1q, C3b, SSA, SSB, and Sm alone or in combination to predict LN. This study evaluated the abovementioned autoantibodies in 40 healthy controls (HCs) and 95 SLE patients with different kidney involvements, including absent (n = 40), inactive (n = 20), and active (n = 35) LN using EIA method. The frequency and odds ratio of anti-dsDNA (71.4%, OR = 4.2), anti-C1q (62.9%, OR = 5.1), and the simultaneous existence of anti-C1q and anti-dsDNA (51.4%, OR = 6) antibodies were significantly higher in the active LN group compared with both inactive and absent LN groups. Moreover, the levels of anti-C1q and anti-dsDNA antibodies positively correlated with disease activity in patients with SLE. The prevalence of these autoantibodies was associated with the severity of LN biopsies. These data suggest that anti-C1q and anti-dsDNA antibodies and also their simultaneous presence may be valuable diagnostic biomarkers for LN prediction in patients with SLE.

Anti-C1q autoantibodies as markers of renal involvement in childhood-onset systemic lupus erythematosus.

BACKGROUND: Childhood-onset systemic lupus erythematosus (cSLE) is rare, and considered more severe than its adult-onset counterpart. Lupus nephritis (LN) occurs more frequently in children, accounting for higher long-term morbidity and mortality compared with adults. Thus, reliable biological markers are needed to predict disease course. This study aimed to investigate the capacity of anti-C1q autoantibodies (Abs) to predict renal flare and global disease activity in cSLE patients, and association with disease activity and kidney involvement. METHODS: Twenty-eight patients with cSLE including 19 patients (68%) with a history of LN were included retrospectively. Anti-C1q Abs were analysed by ELISA at renal flare-up or in the quiescent phase of disease and compared with Farr dsDNA assay. RESULTS: Thirty-one flares occurred during follow-up: anti-C1q Abs were positive in 26 (84%), strongly associated with active disease status (p < 0.0001), and correlated with global disease activity score (p < 0.0001) and anti-dsDNA Abs presence (p < 0.0001). The specificity of anti-C1q Abs was higher than anti-dsDNA (73% vs 19%) in discriminating LN patients, whereas the receiver operating characteristic curves were not statistically different (0.83 ± 0.06 vs 0.78 ± 0.08 respectively), similar to C3 dosage. The presence of anti-C1q Abs at diagnosis was not predictive for global or renal flare. Introduction of a modified SLEDAI score excluding dsDNA Abs, demonstrated a stronger correlation of anti-C1q Abs titres with SLEDAI score in comparison with the Farr test. CONCLUSION: Anti-C1q Abs seem very specific to flares, including LN in children, and their role in daily practice compared with the Farr dsDNA assay needs to be defined.

Diminished capacity of opsonization and immune complex solubilization, and detection of anti-C1q antibodies in sera from patients with hereditary angioedema.

BACKGROUND: Hereditary angioedema (HAE) is an autosomal dominant disease caused by deficiency of C1 esterase inhibitor. Symptoms of HAE include edema, which can potentially cause suffocation. Some patients with HAE exhibit immunological abnormalities, which could prevent an accurate diagnosis. Low levels of complement components are characteristic of HAE and in other settings are thought to reduce elimination of apoptotic cells and immune complex (IC). Thus, we aimed to experimentally clarify the mechanism of immunological abnormalities using sera from HAE patients. METHODS: Serum samples from 18 patients with HAE were collected when free from angioedema attack and compared with normal human pooled sera (NHPS) from 20 healthy volunteers. Opsonization was measured as the rate of phagocytosis of apoptotic Jurkat cells by macrophages differentiated from THP-1 cells incubated with serum. IC solubilization in serum was analyzed by quantifying peroxidase released from a synthetic IC composed of peroxidase and anti-peroxidase antibodies. Anti-C1q antibody levels were detected using an enzyme-linked immunosorbent assay. RESULTS: Serological immunological abnormalities were detected in 12 patients. Opsonization in serum samples from each patient with HAE was lower than that in NHPS (∼20% versus 70%, respectively). The rate of IC solubilization was lower in serum from HAE patients than NHPS. Some patients had high serum anti-C1q antibody levels with increased serum IC levels. CONCLUSIONS: Sera from patients with HAE exhibit anti-C1q antibodies, with a lower capacity for opsonization and IC solubilization. This may be associated with immunological abnormalities and should be investigated further to facilitate accurate diagnosis of HAE.

Complement levels and anti-C1q autoantibodies in patients with neuropsychiatric systemic lupus erythematosus.

OBJECTIVE: The objective of this paper is to analyse serum levels of anti-C1q, C1q circulating immune complexes (CIC), complement activation and complement components in systemic lupus erythematosus (SLE) patients during the first central nervous system neuropsychiatric (NP) event and to define the possible association between these results and clinical and laboratory characteristics. METHODS: A total of 280 patients suspected of having NP involvement due to SLE were recruited in the Leiden NPSLE-clinic. All SLE patients were classified according to the ACR 1982 revised criteria for the classification of SLE. The clinical disease activity was measured by the SLE Disease Activity Index 2000 (SLEDAI-2K) and NP diagnoses were classified according to the 1999 ACR case definitions for NPSLE. We measured in serum of all patients anti-C1q and C1q CIC levels, the activation capacity of complement (CH50 and AP50) and different complement components (C1q, C3, C4). RESULTS: In 92 patients the symptoms were attributed to SLE. NPSLE patients consisted of 63 patients with focal NPSLE and 34 patients with diffuse NPSLE. Anti-C1q antibodies were significantly higher and CH50, AP50 and C3 were significantly lower in NPSLE patients compared with SLE patients without NPSLE. This association was specially marked for diffuse NPSLE while no differences were found for focal NPSLE. After using potential predictors, decreased C4 remained significantly associated with focal NPSLE, but only when antiphospholipid antibodies (aPL) were included in the model. C3 and AP50 were independently associated with diffuse NPSLE. When SLEDAI-2K was included in the model these two associations were lost. When individual NPSLE syndromes were analysed, psychosis and cognitive dysfunction showed significantly lower values of complement activation capacity and all complement components. No significant associations were seen for other individual NPSLE syndromes. CONCLUSION: The associations between diffuse NPSLE and anti-C1q, C3/AP50 and focal NPSLE and C4 may be explained by disease activity and the presence of aPL, respectively. The role of complement activation and complement components in lupus psychosis and cognitive dysfunction merits further research.

Evaluation of Endothelial Cell Adhesion Molecules and Anti-C1q Antibody in Discriminating between Active and Non-Active Systemic Lupus Erythematosus.

BACKGROUND: Detecting the active state of systemic lupus erythematosus (SLE) is important but challenging. This study aimed to determine the diagnostic accuracy of serum endothelial cell adhesion molecules (ICAM-1 and VCAM-1) and anti-C1q antibody in discriminating between active and non-active SLE. METHODS: Using SELENA-SLE disease activity index (SLEDAI), 95 SLE patients (45 active and 50 non-active) were assessed. A score above five was considered indicative of active SLE. The blood samples were tested for serum ICAM-1, VCAM-1 and anti-C1q antibody using enzyme-linked immunosorbent assay (ELISA). RESULTS: The levels of serum VCAM-1 and anti-C1q antibody were significantly higher in active SLE patients. Both VCAM-1 and anti-C1q were able to discriminate between active and non-active SLE (p-value < 0.001 and 0.005, respectively). From the receiver operating characteristic curves (ROCs) constructed, the optimal cut-off values for VCAM-1 and anti-C1q antibody in discriminating between active and non-active SLE were 30.5 ng/mL (69.0% sensitivity, 60.0% specificity, PPV 58.5%, NPV 66.7%) and 7.86 U/mL (75.6% sensitivity, 80% specificity, PPV 77.3%, NPV 78.4%), respectively. However, serum ICAM-1 level was unable to discriminate between the two groups (p-value = 0.193). CONCLUSION: Anti-C1q antibody demonstrated the best diagnostic accuracy in discriminating between active and non-active SLE patients.

Vasculitis secondary to anti-C1q antibodies induced by Toxocariasis.

INTRODUCTION: Vasculitides occurring during parasitic infection are rare and may imply different mechanisms. METHODS: A case report of cutaneous vasculitis and visceral damage during a larva migrans syndrome. RESULTS: We report the case of a 64-year-old man who developed a purpura along with fever, respiratory failure, abdominal pain and myalgia. Immunological screening showed a high titer of both antinuclear antibodies and anti-double-stranded DNA antibodies along with anti-C1q antibodies. Toxocara canis serology returned highly positive with a positive western-blot. The use of antiparasitic drugs in combination with corticosteroids resulted in a dramatic improvement in the patient's condition. CONCLUSIONS: Clinicians should be aware of the systemic complications that may occur during Toxocara canis infection, including vasculitis and immunological disorder.

Acquired Non-histaminergic Angioedema With C1q Autoantibody and Urticaria: A Case Report.

Acquired angioedema (AAE) is a rare disease with life-threatening complications. This pathology has classically been associated with medication use and B cell lymphoproliferative disorders. In this report, we describe a 61-year-old man with a six-year history of angioedema, unrelated to any known triggers or malignancy. Extensive workup has led to a diagnosis of idiopathic nonhistaminergic AAE with normal C1 inhibitor. The patient is currently being treated with lanadelumab, which has resolved the patient's symptoms. This case provides insight into the onset, exploration, treatment, and outcomes of an extremely rare disease process.

Hypocomplementemic urticarial vasculitis syndrome with gastrointestinal vasculitis and crescentic membranoproliferative glomerulonephritis without immune complex deposits.

Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a small vessel vasculitis characterized by hypocomplementemia and urticaria-like exanthema. Some cases also display abdominal pain and membranoproliferative glomerulonephritis (MPGN) with immune complex deposits. We treated a case of HUVS with biopsy-proven gastrointestinal vasculitis and atypical histological findings in a kidney biopsy. The 36-year-old Japanese man, who was previously diagnosed with diffuse panbronchiolitis, visited our hospital due to transient urticaria-like exanthema and rapid deterioration of kidney function. On admission, the skin lesion was found to be only pigmentation, showing no vasculitis by skin biopsy. In laboratory findings, renal dysfunction with hematuria and proteinuria and hypocomplementemia were observed. Gastrointestinal vasculitis was proven by endoscopy and biopsy of the mucosa. Kidney biopsy revealed MPGN with crescents. No immune complex deposits were observed by immunofluorescence or electron microscopy. Additional examination revealed high titers of anti-C1q antibody. The patient was diagnosed with HUVS and treated with corticosteroids and plasma exchange. Although renal function and gastrointestinal vasculitis partially improved, infectious pneumonia frequently recurred. His renal dysfunction began to progress again and reached end-stage kidney disease. This is the first case of HUVS with biopsy-proven gastrointestinal vasculitis and MPGN without immune complex deposits. Notably, in some case of HUVS, anti-C1q antibody may activate the alternative complement pathway without immune complex deposits, resulting in renal injury.

Association of anti-nuclesome and anti C1q antibodies with lupus nephritis in an Egyptian cohort of patients with systemic lupus erythematosus.

INTRODUCTION: Anti-nucleosome and anti-C1q antibodies demonstrated an association with the development of glomerulonephritis in systemic lupus erythematosus (SLE). Some investigators have proposed that monitoring anti-C1q and anti-nucleosome antibodies might be valuable for making predictions about lupus nephritis (LN) and assessment of disease activity as a non-invasive biological marker of renal disease. OBJECTIVES: The current study was proposed to investigate the presence of anti-C1q and anti-nucleosome antibodies in the sera of Egyptian patients with SLE and their association with LN. METHODS: Eighty patients with SLE were included. Patients were classified into, a LN group including 40 cases with active LN (based on the results of renal biopsy and renal SLEDAI≥4) and a non renal SLE group including 40 patients (with no clinical or laboratory evidence of renal involvement that were attributed in the past or present to SLE). They were subjected to full medical history taking, clinical examination, routine laboratory investigations, measurement of antinuclear antibody (ANA), anti-ds DNA, anti-C1q & anti-nucleosome antibodies. RESULTS: Anti-C1q antibody showed a statistically significant association with the presence of vasculitis and nephritis while anti-nucleosome antibody didn't show a significant association with the presence of any clinical features. Double positivity of anti-nucleosome and anti-C1q antibodies showed a statistically significant association with the presence of vasculitis and photosensitivity, high ECLAM score, elevated ESR, low serum albumin and low C3 levels. CONCLUSION: Serum anti-C1q antibody has a significant association with LN while double positive antibodies have a significant association with vasculitis and low C3 levels in Egyptian patients with SLE.

Anti-C1q Antibodies as Occurring in Systemic Lupus Erythematosus Could Be Induced by an Epstein-Barr Virus-Derived Antigenic Site.

Previous infection with Epstein-Barr virus (EBV) is believed to trigger autoimmunity and to drive autoantibody generation as occurring in patients with systemic lupus erythematosus (SLE). Complement C1q and autoantibodies targeting it (anti-C1q) are also considered to be involved in the pathogenesis of SLE, independently of the impact of environmental insults. Still, the circumstances under which these autoantibodies arise remain elusive. By studying a major antigenic site of C1q targeted by anti-C1q (A08), we aimed to determine environmental factors and possible mechanisms leading to the development of anti-C1q. First, we determined antigenic residues of A08 that were critical for the binding of anti-C1q; importantly, we found the binding to depend on amino-acid-identity. Anti-C1q of SLE patients targeting these critical antigenic residues specifically cross-reacted with the EBV-related EBNA-1 (Epstein-Barr virus nuclear antigen 1)-derived peptide EBNA348. In a cohort of 180 SLE patients we confirmed that patients that were seropositive for EBV and recognized the EBNA348 peptide had increased levels of anti-A08 and anti-C1q, respectively. The correlation of anti-EBNA348 with anti-A08 levels was stronger in SLE patients than in matched healthy controls. Finally, EBNA348 peptide-immunization of C1q-/- mice induced the generation of cross-reactive antibodies which recognized both the A08 epitope of C1q and intact C1q. These findings suggest that anti-C1q in SLE patients could be induced by an EBV-derived epitope through molecular mimicry, thereby further supporting the pathogenic role of EBV in the development of SLE. Considering the role of C1q and anti-C1q, modifying the anti-EBV response might be a promising strategy to improve the course of the disease.

Hypocomplementemic Urticarial Vasculitis Syndrome With Crescentic Glomerulonephritis.

Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a rare autoimmune disease characterized by multiple organ system involvement, including renal disease, with low complement levels. We report the case of a 31-year-old woman who presented with nonspecific symptoms including fatigue, diarrhea, macular rash and abdominal pain with acute renal failure leading to end-stage kidney disease. Laboratory results showed hematuria, nephrotic range proteinuria, worsening creatinine and low C1q levels. Left kidney biopsy showed proliferative glomerulonephritis with crescent formation. She was treated with 6 months of intravenous cyclophosphamide, followed by 2 doses of intravenous rituximab (1g each), thereafter maintained on mycophenolate mofetil and glucocorticoid-based therapy. She experienced a full recovery of renal function after 12 months of dialysis dependence. Hypocomplementemic urticarial vasculitis syndrome with crescentic glomerulonephritis is a rare disease with only 5 other reported cases in literature. In our case, we document a delayed but excellent renal recovery during a 2-year follow-up.

Correlation between anti-C1q antibody and disease activity and cellular immune function in patients with systemic lupus erythematosus / 中国医师杂志

Objective:To evaluate the correlation between anti-C1q antibody and disease activity and cellular immune function in patients with systemic lupus erythematosus (SLE).Methods:The clinical data and test indexes of 134 patients with SLE and 90 healthy people who were admitted to Henan Provincial People′s Hospital from June 2017 to February 2018 were collected. The level of anti-C1q antibody was measured by enzyme-linked immunosorbent assay (ELISA), and lymphocyte subsets were measured by flow cytometry. According to the score of Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)-2K, SLE patients were divided into active and inactive groups, and SLE patients were divided into LN group and non-LN group according to the presence or absence of kidney involvement. The levels of anti-C1q antibodies and lymphocyte subsets were compared among the three groups, and correlations between anti-C1q antibodies and disease activity and lymphocytes were analyzed. The predictive value of anti-C1q antibodies and anti double stranded DNA (dsDNA) antibodies for SLE disease activity was evaluated.Results:The anti-C1q antibody level, percentage of T cells and Ts cells in SLE group were higher than those in control group, while the percentage of Th cells, percentage of NK cells, T cell count, Th cell count, B cell count and NK cell count in SLE group were lower than those in control group (all P<0.05); The anti-C1q antibody level in the active group was higher than that in the inactive group, and the counts of T cells, Ts cells, Th cells, B cells and NK cells were lower than those in the inactive group (all P<0.05); The anti-C1q antibody level in LN group was higher than that in non-LN group, and the T cell count, Ts cell count, Th cell count, B cell count, NK cell count were lower than that in non-LN group, with statistically significant difference (all P<0.05). Correlation analysis showed that age, hemoglobin (HB), C3, C4, T cell count, Th cell count, B cell count and NK cell count were negatively correlated with anti-C1q antibody, while SLEDAI-2K, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and anti-dsDNA antibody were positively correlated with anti-C1q antibody (all P<0.05). Receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) of anti-C1q antibody alone in predicting SLE disease activity was 0.702, with a sensitivity of 0.547 and a specificity of 0.827. The combination of anti-C1q and anti ds-DNA antibodies resulted in an AUC of 0.761, a sensitivity of 0.756, and a specificity of 0.691. The combined detection value of the two antibodies predicting SLE disease activity was better than the single detection. Conclusions:Anti-C1q antibody is closely related to disease activity and cellular immune dysfunction, and has certain predictive value in SLE disease activity.

Association Between C1q, TRAIL, and Tim-1 Gene Polymorphisms and Systemic Lupus Erythematosus.

AIM: The present study was designed to examine the relationship between gene polymorphisms of C1q, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), T cell immunoglobulin mucin (Tim-1), and systemic lupus erythematosus (SLE). MATERIALS AND METHODS: A total of 245 SLE patients were selected from February 2012 to August 2016, along with 245 healthy donors as the control group. Genomic DNA was extracted from peripheral blood samples from all subjects followed by mutational analyses. Gene polymorphisms of the C1q gene (rs292001, rs631090, rs294223 loci); the TRAIL gene (1525A/G, 1588A/G, 1595T/C locus); and the Tim-1 gene were detected by sequencing after polymerase chain reaction amplification. The concentration of anti-C1q antibody and the protein levels of sTRAIL/Tim-1 in serum of all subjects were measured by enzyme-linked immunosorbent assay. RESULTS: As for the C1q gene, the frequency of the T allele at the rs631090 locus in the study group was lower than that in the controls, and the frequency of the C allele was higher in the study group than in the healthy donors. The frequency of the G allele at the 1525A/G locus of TRAIL gene in the study group was significantly higher than those in the control group. The frequency of the G allele at -1454G/A of Tim-1 was dramatically higher in the study group than in the control group. Anti-C1q antibody concentrations of subjects carrying CC and CT genotype at the rs631090 locus were statistically higher than TT genotype carriers. The sTRAIL protein level of the TRAIL 1525A/G GG genotype carriers was significantly higher than that of GA and AA genotype carriers, as well as CC genotype carriers at 1595T/C site compared with CT/TT genotype carriers. GG genotype carriers at -1454G/A had higher Tim-1 expression levels than GA/AA genotype carriers. CONCLUSION: The C allele at the rs631090 locus of C1q, the G allele at 1525A/G site of TRAIL, and the G allele of Tim-1 at -1454G/A site are susceptibility variants associated with SLE.

Clinical utility of anti-C1q antibody in primary and secondary vasculitic conditions.

OBJECTIVE: Anti-C1q antibodies (Anti-C1q Ab) are seen in hypocomplementemic urticarial vasculitis syndrome (HUVS), infection-associated vasculitis such as hepatitis C virus-related vasculitis and in autoimmune diseases such as rheumatoid vasculitis, polyarteritis nodosa, giant cell arteritis, vascular Behcet's disease, and cryoglobulin associated vasculitis. Aim of this study is to evaluate the presence of Anti-C1q Ab in vasculitis and to determine if any difference exists between primary and secondary vasculitis in relation to this antibody. PATIENTS AND METHODS: Consecutive patients with diagnosis of either a primary or secondary vasculitis were recruited. Primary vasculitis were diagnosed by the American College of Rheumatology 1990 criteria. Clinical features and serological markers were noted. Anti-C1q Ab was assayed by commercially available ELISA kit (Demeditec Diagnostics GmbH, Germany). RESULTS: Sixty-four patients were recruited for the study comprising of 41 primary vasculitis and 23 secondary vasculitis cases. No difference in Anti-C1q Ab levels between primary and secondary vasculitis was noted. Four patients were positive for Anti-C1q Ab out of the 64 patients. Of the four, one patient was diagnosed as HUVS, 2 patients as systemic lupus erythermatosus with vasculitis (16.7%) and another patient was diagnosed as rheumatoid arthritis with vasculitis (14.28%). Anti-C1q Ab negatively correlated with age and C3, but it correlated positively with erythrocyte sedimentation rate (ESR) in vascultic patients. CONCLUSION: Presence of anti-C1q Ab did not differ between the patients with primary and secondary vasculitis. Anti-C1q Ab titers correlated with younger age, high ESR, and low C3 in patients with vasculitis in our study.

Complement and thrombosis in the antiphospholipid syndrome.

The involvement of complement activation in the pathophysiology of antiphospholipid syndrome (APS) was first reported in murine models of antiphospholipid antibody (aPL)-related pregnancy morbidities. We previously reported that complement activation is prevalent and may function as a source of procoagulant cell activation in the sera of APS patients. Recently, autoantibodies against C1q, a component of complement 1, were reported to be correlated with complement activation in systemic lupus erythematosus. These antibodies target neoepitopes of deformed C1q bound to various molecules (i.e., anionic phospholipids) and induce accelerated complement activation. We found that anti-C1q antibodies are more frequently detected in primary APS patients than in control patients and in refractory APS patients with repeated thrombotic events. The titer of anti-C1q antibodies was significantly higher in refractory APS patients than in APS patients without flare. The binding of C1q to anionic phospholipids may be associated with the surge in complement activation in patients with anti-C1q antibodies when triggered by 'second-hit' biological stressors such as infection. Such stressors will induce overexpression of anionic phospholipids, with subsequent increases in deformed C1q that is targeted by anti-C1q antibodies.

The value of anti-C1q antibody test in lupus nephritis patients / 中华风湿病学杂志

Objective@#To assess the association between lupus nephritis disease activity and anti-C1q antibodies.@*Methods@#The study analyzed the medical records of 98 patients with lupus nephritis (LN), 35 patients without lupus nephritis. LN disease activity was measured by the systemic lupus international collaborating clinics (SLICC) renal activity score of 2008. All biopsied tissues were scored based on the International society of nephrology/Renal pathology society (ISN/RPS) 2003 LN pathological typing standards, acute and chronic index scores were used to evaluate the activities of lupus. All patients were test for the levels of anti-dsDNA and anti-C1q antibodies using the enzyme-linked immuno sorbent assay (ELISA), C3, C4, 24-hour urinary protein performed in parallel. For normally distributed quantitative parameters, the differences between groups were assessed by t test. Mann-Whitney U test was performed for non-normally distributed data. The cut-off values were evaluated by using receiver operating characteristic (ROC). The Spearman methods were used to test correlations.@*Results@#Patients with LN had a higher levels of anti-C1q antibodies than patients without lupus nephritis [3.94 (10.2, 91.3) AU/ml与6.9 (2.0, 15.4) AU/ml; Z=-4.299, P<0.01]. Patients with inactive lupus nephritis had higher levels of C1q, C3, C4 than active LN (t=2.393, 3.777, 2.557; P<0.05). Patients with active lupus nephritis had higher levels of anti-C1q antibodies than inactive LN (Z=-4.632, P<0.01). Anti-C1q antibody levels were positively correlated with levels of 24-hour urinary protein, AI score (r=0.327, P<0.01) and SLICC score (r=0.493, P<0.01), and were negatively correlated with serum C1q (r=-0.373, P<0.01), C3 (r=-0.532, P<0.01) and C4 (r=-0.463, P<0.01). The optimal cutoff value of Anti-C1q for a diagnosis of active LN was 48.9 RU/ml, and the sensitivity and specificity were 62.5% and 80%, respectively. The area under the curve (AUC) was 0.771.@*Conclusion@#Anti-C1q antibodies are more closely correlated with renal disease activity, and anti-C1q antibody is an important serum marker for monitoring LN activity, but its pathological mechanism in the pathogenesis of LN still needs to be further explored.

Association of anti-nuclesome and anti C1q antibodies with lupus nephritis in an Egyptian cohort of patients with systemic lupus erythematosus

Abstract Introduction: Anti-nucleosome and anti-C1q antibodies demonstrated an association with the development of glomerulonephritis in systemic lupus erythematosus (SLE). Some investigators have proposed that monitoring anti- C1q and anti-nucleosome antibodies might be valuable for making predictions about lupus nephritis (LN) and assessment of disease activity as a non-invasive biological marker of renal disease. Objectives: The current study was proposed to investigate the presence of anti-C1q and anti-nucleosome antibodies in the sera of Egyptian patients with SLE and their association with LN. Methods: Eighty patients with SLE were included. Patients were classified into, a LN group including 40 cases with active LN (based on the results of renal biopsy and renal SLEDAI≥4) and a non renal SLE group including 40 patients (with no clinical or laboratory evidence of renal involvement that were attributed in the past or present to SLE). They were subjected to full medical history taking, clinical examination, routine laboratory investigations, measurement of antinuclear antibody (ANA), anti-ds DNA, anti-C1q & anti-nucleosome antibodies. Results: Anti-C1q antibody showed a statistically significant association with the presence of vasculitis and nephritis while anti-nucleosome antibody didn't show a significant association with the presence of any clinical features. Double positivity of anti-nucleosome and anti-C1q antibodies showed a statistically significant association with the presence of vasculitis and photosensitivity, high ECLAM score, elevated ESR, low serum albumin and low C3 levels. Conclusion: Serum anti-C1q antibody has a significant association with LN while double positive antibodies have a significant association with vasculitis and low C3 levels in Egyptian patients with SLE.