Association between the presence of anti-C1q antibodies and active nephritis in patients with systemic lupus erythematosus

Lupus nephritis (LN) is a severe complication of systemic lupus erythematosus (SLE). A retrospective analysis was carried out on a group of 24 patients with SLE to evaluate whether the presence of anti-C1q antibodies (anti-C1q) is related to renal involvement and to explore the behaviour of anti-C1q with respect to LN during a four-year follow-up period. A first serum sample stored at the serum bank, taken not more than three years after SLE diagnosis and one serum sample per year for the subsequent four years were used to detect anti-C1q. Lupus clinical manifestations and serological markers of activity corresponding to the date of each serum sample selected were collected from medical records. In the first serum sample, anti-C1q were found in 8 active SLE. LN was confirmed by histology in 5/8 patients who were positive for anti-C1q and in 1/16 patients who were negative for these autoantibodies (p = 0.0069). Three patients (3/8) had anti-C1q without renal involvement but with lupus skin manifestation. Anti-C1q levels decreased in 3/5 patients with LN who responded to treatment and remained higher in 2/5 patients who needed a new renal biopsy which showed severe renal disease. The 15 patients without severe kidney disease and anti-C1q negative at diagnosis did not develop LN and anti-C1q remained negative in the 4 years of follow up. Anti-C1q were found in SLE patients with active renal involvement or with lupus skin disease. The absence of anti-C1q seemed to be linked to low probabilities of renal involvement.

[Elevated levels of circulating immune complexes -C3d and-C1q as a criterion for acute extraintestinal manifestations of ulcerative colitis]

During ulcerative colitis in the exacerbation phase the high level of circulating immune complexes -C1q and -C3d (CIC-C1q and -C3d) was detected in 35.4% and 28.9% of patients respectively. This raise of CIC-C1q and -C3d level was accompanied by increase of clinical and endoscopic activity of ulcerative colitis (AC). In 45.4% of AC patients with extraintestinal onsets CIC-C3d was detected and only in 11.7% of patients CIC-C1q was found. These data confirm that activation of the humoral immunity accompanied by increase in formation of immune complexes is characteristic for AC patients with extraintestinal onsets. CIC emergence in serum of AC patients is considered as a prognostically unfavorable sign indicating that the disease may be accompanied by extraintestinal onsets.

[Expressions of complement C1q and C3c in rat brain tissues with cerebral ischemia/reperfusion injury]

OBJECTIVE

To observe the expression levels of the complement fragment C1q and C3c in rat brain tissues with cerebral ischemia-reperfusion (I/R) injury, and explore the correlation, roles and mechanism of complement reaction and microglia in the brain I/R injury.

METHODS

A total of 48 male Sprague-Dawley rats were randomly divided into normal control group, sham group, I/R 24 h, 72 h, 7 d, 15 d model groups. Suture occlusion method was operated to establish focal middle cerebral artery occlusion (MCAO) and reperfusion models. The Nissl staining was applied to observe the structure of neurons, and immunohistochemistry was applied to detect CD11b, C1q and C3c expression.

RESULTS

Compared with the sham group, Nissl staining reaction in brain tissues was stronger in the I/R 24 h group, and then became weaker, and the reduction was the most significant in the I/R 72 h group. The expression of CD11b protein increased in the I/R 24 h group and reached the peak value in the I/R 72 h group, followed by gradually reducing. Compared with the sham group, all the model groups were significantly stronger in CD11b expression (P<0.05). C1q and C3c sharply increased in the brain tissue of I/R 24 h group and peaked in the I/R 7 d group, and then presented a downward trend; the differences between the sham group and all the model groups were of statistical significance (P<0.05).

CONCLUSION

The expression levels of C1q and C3c are positively correlated with CD11b protein in rat brain tissues with cerebral I/R injury, suggesting that cerebral I/R injury inintiate the brain innate immune response, activates complement C1q and C3c as well as microglia, thus playing the role of protection or damage in cerebral I/R injury.

Clinical and immunopathological features of patients with lupus hepatitis

BACKGROUND

Lupus hepatitis is yet to be characterized based on its clinical features and is often difficult to differentially diagnose from other liver diseases. We aimed to elucidate clinical, histopathological and immunopathological features of lupus hepatitis and to evaluate primarily the effectiveness of liver immunopathological manifestations on differential diagnosis of lupus hepatitis from other liver diseases.

METHODS

A retrospective study was performed to analyze clinical features of lupus hepatitis in 47 patients out of 504 inpatients with systemic lupus erythematosus (SLE) in First Affiliated Hospital of Sun Yat-sen University, China from May 2006 to July 2009, and to evaluate the association between lupus hepatitis and SLE activity. Additionally, liver histopathological changes by hematoxylin and eosin (HE) staining and immunopathological changes by direct immunofluorescence test in 10 lupus hepatitis cases were analyzed and compared to those in 16 patients with other liver diseases in a prospective study.

RESULTS

Of 504 SLE patients, 47 patients (9.3%) were diagnosed to have lupus hepatitis. The prevalence of lupus hepatitis in patients with active SLE was higher than that in those with inactive SLE (11.8% vs. 3.2%, P < 0.05). The incidence of hematological abnormalities in patients with lupus hepatitis was higher than that in those without lupus hepatitis (40.4% vs. 21.7%, P < 0.05), such as leucocytes count (2.92×10(9)/L vs. 5.48×10(9)/L), platelets count (151×10(9)/L vs. 190×10(9)/L), serum C3 and C4 (0.34 g/L vs. 0.53 g/L; 0.06 g/L vs. 0.09 g/L) (P < 0.05); 45 of 47 (95.7%) lupus hepatitis patients showed 1 upper limit of normal (ULN) < serum ALT level < 5 ULN. The liver histopathological features in patients with lupus hepatitis were miscellaneous and non-specific, similar to those in other liver diseases, but liver immunopathological features showed positive intense deposits of complement 1q in 7/10 patients with lupus hepatitis and negative complement 1q deposits in all patients with other liver diseases (Fisher's exact test, P = 0.011).

CONCLUSIONS

Lupus hepatitis was not infrequent in active SLE patients which would be one of the indices indicating SLE activity. Positive intense deposit of complement 1q in liver may be a characteristic immunopathological feature of lupus hepatitis, which provides a new way to differentially diagnose lupus hepatitis from other liver diseases.

Three-month treatment with pioglitazone reduces circulating C1q-binding adiponectin complex to total-adiponectin ratio, without changes in body mass index, in people with type 2 diabetes

We measured circulating C1q-binding adiponectin (C1q-APN) levels before and after 3-month treatment with pioglitazone in people with type 2 diabetes. The results indicate 3-month treatment with pioglitazone reduces circulating levels of C1q-APN/total-adiponectin ratio without changes in body mass index.

C1q nephropathy with acute hemolytic uremic syndrome

C1q nephropathy with hemolytic uremic syndrome (HUS) is an uncommon combination associated with rapidly progressive renal failure. We report a case of C1q nephropathy with HUS in an 18-year-old man associated with rapidly progressive renal failure. The patient did not respond to treatment with steroids and was started on maintenance hemodialysis. C1q nephropathy with HUS is rare and can lead to rapidly progressive renal failure.

Significance of complement components C1q and C4 bound to circulating immune complexes in juvenile idiopathic arthritis: support for classical complement pathway activation

OBJECTIVES

Immune complexes (ICs) from sera of juvenile idiopathic arthritis (JIA) patients show increased complement opsonisation; however, a definitive role for involvement of the classical or alternative pathway is not entirely clear. To delineate the role of these pathways, we measured activated complement products bound to circulating IC (CICs) in the sera of JIA patients.

METHODS

Sera from 100 JIA patients and 22 healthy children were collected. C1q, C4, C3, C3d, and membrane attack complex (MAC) bound to CICs were measured by enzyme-linked immunosorbent assay. Data was compared to IgM rheumatoid factor (RF), IgG anti-cyclic citrullinated peptide (CCP) antibodies, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) levels.

RESULTS

Mean levels of C1q, C4, and MAC bound to CICs were significantly elevated in JIA patients compared to healthy children. C1q correlated significantly with C4 and MAC bound to CICs and C4 and MAC also demonstrated significant correlation. No significant differences were noted in complement components bound to CICs when evaluating IgM RF, anti-CCP antibody, and CRP positivity. A significant correlation was noted between MAC bound to CICs and ESR. C1q and MAC bound to CICs mean levels were significantly higher in patients with an elevated ESR compared to those with a normal ESR level.

CONCLUSIONS

JIA patients have elevated levels of complement components bound to CICs, particularly from the classical pathway. Moreover, classical pathway components were associated with ESR, a marker of disease activity. MAC bound to CICs also correlated significantly with ESR, further supporting the notion of complement-mediated tissue injury that is triggered by IC-mediated classical pathway activation.

Proteomic analyses of aortic wall in patients with abdominal aortic aneurysm

AIM

The mechanisms underlying the formation of abdominal aortic aneurysms have yet to be fully clarified. To identify key proteins generally involved in aneurysmal formation, proteomic profiles were compared between aneurysmal and non-aneurysmal regions of aortic walls from patients with abdominal aortic aneurysm.

METHODS

Aortic wall specimens were obtained from three patients with abdominal aortic aneurysm. Protein profiles of aortic wall samples including vascular media and adventitia were compared between aneurysmal and non-aneurysmal regions in each patient using two-dimensional fluorescence difference gel electrophoresis (2D-DIGE). Protein spots expressed differently between the two regions were identified by tandem mass spectrometry and verified by immunohistochemical investigations.

RESULTS

Image analysis of 2D-DIGE gels revealed 22 proteins spots expressed differently between aneurysmal and non-aneurysmal regions in all three patients. Among these, five protein spots that were up-regulated in the AA regions were successfully identified as complement component C4, fragments of the fibrinogen alpha or beta subunits, and actin. Immunohistochemical studies showed massive deposition of fibrin/fibrinogen or its fragments in the media, and complement C1q component, the molecule starting the classical complement pathway, in all three layers of the aneurysmal region.

CONCLUSION

Our proteomic and subsequent immunohistochemical studies revealed significant fibrinogenesis and fibrinolysis in the media, and activation of the classical complement pathway in all three layers of the aneurysmal region. These data promote understanding of mechanisms behind the formation of abdominal aortic aneurysms.

Clinical management of patients with systemic lupus erythematosus (SLE) with different C1q-CIC and C3 concentrations

Over the third of SLE (Systemic Lupus Erythematosus) patients have a high level auto-antibodies-antigen complex that contains some complement proteins, especially C1q as the trigger protein in the classical complement activation pathway. So, the SLE, as an autoimmune disease, is certainly related to disorders caused by activation of complement system, that finally leads to tissue damage. It may also be caused by hereditary deficiency (complement genes mutations). In such case, some components of the complement system might be inactivated. There are mutations that cause disorders in each of three complement system activation pathways (classical, alternative and lectin).The serum samples of SLE patients show the presence of specific autoantibodies for some complement components. Today, for clinical management of SLE patients, determination of level of C1q-CIC and C3 complement component in serum specimens have great diagnostic and therapeutic importance. During the year 2000, we analyzed a numerous serum samples from patients suspected to autoimmune diseases (SLE especially). The samples were collected from several clinics in the Clinical Center of University of Sarajevo, mostly from Clinic of Infectious Diseases, Pediatrics, Internal Medicine and Gastroenterohepatology Clinic. Primary samples went through screening for the presence of ANA using ANA-IFA method and further characterization of ANA positive samples was carried out using IFA-ANA titration, ELISA and nephelometry.

[C1q nephropathy. Report of one case]

Clq nephropathy (Clq N) is an infrequent disease and only about 100 cases have been reported. It is defined by a pattern of immunofluorescence (IF) with dominant or co-dominant complement Clq with electron-dense deposits in the mesangium, without clinical or serological features of Lupus Nephritis. The most common histopathological findings of ClqN are focal segmental glomerulosclerosis and Minimal Change Disease. We report a 17 year-old male patient with an isolated selective proteinuria found in a routine study. He had normal renal function and urine culture was negative. Serum lipids, liver enzymes an complement were all normal. Serum antinuclear and anti-DNA antibodies, antineutrophil cytoplasmic antibodies (ANCA), HIV, Hepatitis B and C serology, were negative. Renal and abdominal ultrasonography was normal. The histopathological study revealed segmental glomerular sclerosis, moderate increase of mesangial matrix, Bowmann capsule adhesions and fucsinophil deposits in mesangium. The IF was positive (dominant) for Clq (+++) and IgA, IgG, IgM, C3++, all of them with a granular mesangial distribution. Ultrastructural findings were pedicelar effacement and paramesangial electron-dense deposits. Tubular reticular inclusions (TRI) were not found. Remission of proteinuria was reached after 18 months of treatment with enalapril and losartan. The patient remains with normal renal function. Clinical findings, negative serology for Lupus, light microscopy IF with dominant positivity for Clq, absence of TRI and paramesangial electron-dense deposits in electron microscopy lead us to the diagnosis of ClqN. A poor response to steroid therapy was described in ClqN. Thus it was worthwhile to differentiate it from lupus nephritis, that is responsive to steroids.

[Establishment and optimization of detection of the hepatitis B immune complexes]

OBJECTIVE

To establish and optimize methods to detect the immune complexes (IC) of hepatitis B virus directly.

METHODS

A C1q solid phase ELISA, mouse anti-HBs MAb solid phase ELISA and the complement consumption assay were established to detect the IC and these methods were optimized.

RESULTS

All the three methods were highly sensitive, specific and reproducible. The C1q used for coating tended to lose its activity easily at room temperature. Although strict requirements are needed for the raw and processed materials for complement consumption assay and the process of manipulation is complex, it can quantitatively detect IC. Comparing to the C1q solid ELISA and complement consumption assay, the mouse anti-HBs MAb solid phase ELISA has its own merits: convenience and stability.

CONCLUSION

Mouse anti-HBs MAb solid phase ELISA is the best way to detect IC directly.

Urticarial vasculitis

Urticarial vasculitis can present in a variety of ways, ranging from a primarily cutaneous disease consisting of chronic urticaria to a lupus-like disease with severe cardiopulmonary disease. Low complement levels and positive anti-C1q antibodies are markers of more severe disease. Care must be taken to look for an underlying condition. The mainstay of therapy is treatment of any underlying condition. Therapies most often employed include corticosteroids, antihistamine, and dapsone, but many others have been utilized.

Activated complement components and complement activator molecules on the surface of cell-derived microparticles in patients with rheumatoid arthritis and healthy individuals

OBJECTIVES

In vitro, microparticles can activate complement via the classical pathway. If demonstrable ex vivo, this mechanism may contribute to the pathogenesis of rheumatoid arthritis (RA). We therefore investigated the presence of activated complement components and complement activator molecules on the surface of cell-derived microparticles of RA patients and healthy individuals.

METHODS

Microparticles from synovial fluid (n = 8) and plasma (n = 9) of 10 RA patients and plasma of sex- and age-matched healthy individuals (n = 10) were analysed by flow cytometry for bound complement components (C1q, C4, C3) and complement activator molecules (C-reactive protein (CRP), serum amyloid P component (SAP), immunoglobulin (Ig) M, IgG).

RESULTS

Microparticles with bound C1q, C4, and/or C3 were abundant in RA synovial fluid, while in RA and control plasma much lower levels were present. Microparticles with bound C1q correlated with those with bound C3 in synovial fluid (r = 0.961, p = 0.0001), and with those with bound C4 in plasma (RA: r = 0.908, p = 0.0007; control: r = 0.632, p = 0.0498), indicating classical pathway activation. In synovial fluid, microparticles with IgM and IgG correlated with those with C1q (r = 0.728, p = 0.0408; r = 0.952, p = 0.0003, respectively), and in plasma, microparticles with CRP correlated with those with C1q (RA: r = 0.903, p = 0.0021; control: r = 0.683, p = 0.0296), implicating IgG and IgM in the classical pathway activation in RA synovial fluid, and CRP in the low level classical pathway activation in plasma.

CONCLUSIONS

This study demonstrates the presence of bound complement components and activator molecules on microparticles ex vivo, and supports their role in low grade complement activation in plasma and increased complement activation in RA synovial fluid.

[Two cases of C1INH deficiency with paroxysmal abdominal pain]

We encountered two cases of C1 inhibitor deficiency (26-year-old man and 29-year-old woman). They had been suffering from paroxysmal abdominal pain for many years. Imaging studies showed wall thickening of the intestine and ascites and diagnosis was difficult. Decreased serum levels of C4 and C1INH activity indicated a diagnosis of C1INH deficiency. Although C1INH deficiency is rare, it should be considered as a differential diagnosis in young patients with paroxysmal abdominal pain.

Acquired angioedema in non-Hodgkin’s lymphoma

This paper describes a middle-aged patient who developed repeated episodes of swelling of the orofacial tissues after dental treatment. On investigation, C1 inhibitor, C1q, C2, and C4 levels were all markedly reduced, and a diagnosis of acquired C1 inhibitor deficiency was made. The patient had been diagnosed with non-Hodgkin's lymphoma (NHL) 2 years previously and had undergone a successful course of chemotherapy. The development of her episodes of angioedema prompted thorough reinvestigation and a recurrence of NHL was identified. Therefore, acquired C1 inhibitor deficiency heralded a recurrence, although this had not been a manifestation when NHL was first diagnosed. The patient underwent a further course of chemotherapy and remains well, although C1 inhibitor, C1q, C2, and C4 levels remain reduced.

Application of complement 1q for the site-selective recognition of immune complex in protein chip

Complement 1q (C1q) was applied for the specific recognition of antibody-antigen complex in antibody-based protein chip. The specific binding of C1q to antibody-antigen complex was investigated by surface plasmon resonance (SPR) with respect to Yersinia entericolitica, Salmonella typimurium, insulin, and bovine serum albumin. The protein chip was fabricated with two different kinds of antibodies a zigzag configuration. When one of antigens and fluorescein-isothiocyanate (FITC)-labeled C1q was applied on the protein chip, the specific binding event of C1q to immune complexes formed on protein chip was observed by fluorescence microscopy. These results implicate that the C1q can be used as an alternative to many antibodies that may be utilized individually on each spot of the protein chip.

Presence of plasma complement regulatory proteins clusterin (Apo J) and vitronectin (S40) on circulating immune complexes (CIC)

The complement regulatory (CR) proteins clusterin and vitronectin bind to the membrane attack complex (MAC) and thus prevent cytolysis. In this report, we demonstrate the presence of both of these CR proteins on MAC bound to circulating immune complexes (CIC). We measured the amount of clusterin and vitronectin on MAC in plasma, also referred to as soluble MAC (SMAC), as well as on MAC bound to CIC (MAC-CIC), using antibody directed to polymerized C9 in systemic lupus erythematosus (SLE) patients. We observed a strong correlation among the quantities of SMAC and MAC-CIC. The amount of both clusterin and vitronectin associated with MAC-CIC was two- to threefold higher in comparison to the SMAC. Patients with high levels of clusterin and vitronectin demonstrated renal involvement. We hypothesize that these complement regulatory proteins besides regulating the insertion of MAC play other critical roles, in disease pathogenesis.

Preclinical evaluation of the neuroprotective effect of soluble complement receptor Type 1 in a nonhuman primate model of reperfused stroke

Object

Postischemic cerebral inflammatory injury has been extensively investigated in an effort to develop effective neuroprotective agents. The complement cascade has emerged as an important contributor to postischemic neuronal injury. Soluble complement receptor Type 1 (sCR1), a potent inhibitor of complement activation, has been shown to reduce infarct volume and improve functional outcome after murine stroke. Given numerous high-profile failures to translate promising antiinflammatory strategies from the laboratory to the clinic and given the known species-specificity of the complement cascade, the authors sought to evaluate the neuroprotective effect of sCR1 in a nonhuman primate model of stroke.

Methods

A total of 48 adult male baboons (Papio anubis) were randomly assigned to receive 15 mg/kg of sCR1 or vehicle. The animals were subjected to 75 minutes of middle cerebral artery occlusion/reperfusion. Perioperative blood samples were analyzed for total complement activity by using a CH50 assay. Infarct volume and neurological scores were assessed at the time the animals were killed, and immunohistochemistry was used to determine cerebral drug penetration and C1q deposition. An interim futility analysis led to termination of the trial after study of 12 animals. Total serum complement activity was significantly depressed in the sCR1-treated animals compared with the controls. Immunostaining also demonstrated sCR1 deposition in the ischemic hemispheres of treated animals. Despite these findings, there were no significant differences in infarct volume or neurological score between the sCR1- and vehicle-treated cohorts.

Conclusions

A preischemic bolus infusion of sCR1, the most effective means of administration in mice, was not neuroprotective in a primate model. This study illustrates the utility of a translational primate model of stroke in the assessment of promising antiischemic agents prior to implementation of large-scale clinical trials.

Anti-C1q antibodies in hepatitis C virus infection

Autoantibodies against C1q have been described in many immune-complex diseases including hypocomplementaemic urticarial vasculitis and systemic lupus erythematosus (SLE). No study has focused on the role of anti-C1q antibodies in hepatitis C virus (HCV) infection. The aim of this study was (i) to evaluate the prevalence of anti-C1q antibodies in HCV infection; and (ii) to analyse the association of anti-C1q antibodies with clinical and biological features of HCV-mixed cryoglobulinaemia (MC) vasculitis. We searched for anti-C1q antibodies using an enzyme-linked immunosorbent assay (ELISA) test in 111 HCV patients (75 had cryoglobulin and 23 systemic vasculitis), 60 SLE patients and 109 blood donors. Anti-C1q antibodies were detected in 26% of HCV patients compared to 10% of healthy donors (P < 0.01), and 38% in patients with SLE. Although there was a higher prevalence of anti-C1q antibodies among HCV patients with type III cryoglobulin (50%, P < 0.01), the overall prevalence of anti-C1q antibodies was similar in HCV patients being cryoglobulin-positive or cryoglobulin-negative (26%versus 25%, P = 0.98). A significant association was found between anti-C1q antibodies and low C4 fraction of complement (P < 0.05). No association was found between anti-C1q antibodies and HCV genotype, severity of liver disease or with specific clinical signs of HCV-MC vasculitis. This study shows an increased prevalence of anti-C1q antibodies in HCV-infected patients. Anti-C1q antibodies were associated with low C4 levels. No association was found between anti-C1q antibodies and HCV-MC vasculitis, nor between anti-C1q antibodies and cryoglobulinaemia.

Retinal synthesis and deposition of complement components induced by ocular hypertension

Inappropriate activity of the complement cascade contributes to the pathophysiology of several neurodegenerative conditions. This study sought to determine if components of the complement cascade are synthesized in the retina following the development of ocular hypertension (OHT) and if complement accumulates in association with retinal ganglion cells. Toward this goal the gene expression levels of complement components 1qb (C1qb) and 3 (C3) were determined in the retina by quantitative polymerase chain reaction in human eyes with elevated intraocular pressure (IOP) and healthy retinal tissue as well as in a rat model of OHT induced by laser cauterization of the trabecular meshwork and episcleral veins. Immunohistochemical methods were employed to determine the sites of complement deposition in the retina and optic nerve head. Our data demonstrate that transcript levels for C1q and C3 are significantly elevated in retinae subjected to OHT, both in the animal model as well as in human eyes. Immunohistochemical analyses indicate that C1q and C3 accumulate specifically in the retinal ganglion cell layer and the nerve fiber layer. In addition, we demonstrate that the terminal complement complex, or membrane attack complex, is formed both in the human and rat model as a consequence of OHT. Complement activation, particularly formation of membrane attack complexes, has the potential to exacerbate ganglion cell death through bystander lysis or glial cell activation. The results show that complement activation occurs in the retina that has been subjected to elevated IOP, and may have implications in pathophysiology of glaucoma.