Dissecting the impact of complement component 4A in bipolar disorder.

The genetic overlap between schizophrenia (SZ) and bipolar disorder (BD) is substantial. Polygenic risk scores have been shown to dissect different symptom dimensions within and across these two disorders. Here, we focused on the most strongly associated SZ risk locus located in the extended MHC region, which is largely explained by copy numbers of the gene coding for complement component 4A (C4A). First, we utilized existing brain tissue collections (N = 1,202 samples) and observed no altered C4A expression in BD samples. The generated C4A seeded co-expression networks displayed no genetic enrichment for BD. To study if genetically predicted C4A expression discriminates between subphenotypes of BD, we applied C4A expression scores to symptom dimensions in a total of 4,739 BD cases with deep phenotypic data. We identified a significant association between C4A expression and psychotic mood episodes in BD type 1 (BDI). No significant association was observed between C4A expression and the occurrence of non-affective psychotic episodes in BDI, the psychosis dimensions in the total BD sample, or any other subphenotype of BD. Overall, these results points to a distinct role of C4A in BD that is restricted to vulnerability for developing psychotic symptoms during mood episodes in BDI.

Complement C4-A and Plasminogen as Potential Biomarkers for Prediction of Papillary Thyroid Carcinoma.

Background: Early diagnosis and therapy of papillary thyroid carcinoma (PTC) is essential for reducing recurrence and improving the long-term survival. In this study, we aimed to investigate the proteome profile of plasma and screen unique proteins which could be used as a biomarker for predicting PTC. Methods: Serum samples were collected from 29 PTC patients and 29 nodular goiter (NG) patients. Five PTC serum samples and five NG serum samples were selected for proteome profiles by proteomics. Eight proteins in PTC and NG serum samples were selected for confirmation by enzyme-linked immunosorbent assay analysis. Receiver operating characteristic curves was used to evaluate the diagnostic value of potential biomarkers. Results: Complement C4-A (C4A) and plasminogen (PLG) were significantly lower in serum samples of PTC patients compared with NG patients. C4A was observed to have excellent diagnostic accuracy for PTC, with a sensitivity of 91.67% and specificity of 83.33%. The diagnostic value of PLG for PTC was demonstrated by a sensitivity at 87.50% and specificity at 75.00%. The AUC for C4A and PLG was 0.97 ± 0.02 and 0.89 ± 0.05. Conclusion: C4A and PLG appeared to be excellent potential biomarkers for the prediction of PTC.

Variants at the MHC Region Associate With Susceptibility to Clostridioides difficile Infection: A Genome-Wide Association Study Using Comprehensive Electronic Health Records.

Background: Clostridioides difficile is a major cause of healthcare-associated and community-acquired diarrhea. Host genetic susceptibility to Clostridioides difficile infection has not been studied on a large-scale. Methods: A total of 1,160 Clostridioides difficile infection cases and 15,304 controls were identified by applying the eMERGE Clostridioides difficile infection algorithm to electronic health record data. A genome-wide association study was performed using a linear mixed model, adjusted for significant covariates in the full dataset and the antibiotic subgroup. Colocalization and MetaXcan were performed to identify potential target genes in Clostridioides difficile infection - relevant tissue types. Results: No significant genome-wide association was found in the meta-analyses of the full Clostridioides difficile infection dataset. One genome-wide significant variant, rs114751021, was identified (OR = 2.42; 95%CI = 1.84-3.11; p=4.50 x 10-8) at the major histocompatibility complex region associated with Clostridioides difficile infection in the antibiotic group. Colocalization and MetaXcan identified MICA, C4A/C4B, and NOTCH4 as potential target genes. Down-regulation of MICA, upregulation of C4A and NOTCH4 was associated with a higher risk for Clostridioides difficile infection. Conclusions: Leveraging the EHR and genetic data, genome-wide association, and fine-mapping techniques, this study identified variants and genes associated with Clostridioides difficile infection, provided insights into host immune mechanisms, and described the potential for novel treatment strategies for Clostridioides difficile infection. Future replication and functional validation are needed.

Complement C4A Regulates Autoreactive B Cells in Murine Lupus.

Systemic lupus erythematosus (SLE) is a severe autoimmune disease mediated by pathogenic autoantibodies. While complement protein C4 is associated with SLE, its isoforms (C4A and C4B) are not equal in their impact. Despite being 99% homologous, genetic studies identified C4A as more protective than C4B. By generating gene-edited mouse strains expressing either human C4A or C4B and crossing these with the 564lgi lupus strain, we show that, overall, C4A-like 564Igi mice develop less humoral autoimmunity than C4B-like 564Igi mice. This includes a decrease in the number of GCs, autoreactive B cells, autoantibodies, and memory B cells. The higher efficiency of C4A in inducing self-antigen clearance is associated with the follicular exclusion of autoreactive B cells. These results explain how the C4A isoform is protective in lupus and suggest C4A as a possible replacement therapy in lupus.

Endothelial Microparticles and Systemic Complement Activation in Patients With Chronic Kidney Disease.

BACKGROUND: Endothelial microparticles are associated with chronic kidney disease (CKD) and complement activation. We hypothesized that the complement pathway is activated in patients with CKD via endothelial microparticles and that complement activation correlates with endothelial dysfunction in CKD. METHODS AND RESULTS: We analyzed complement data of 30 healthy subjects, 30 patients with stage III/IV CKD, and 30 renal transplant recipients with stage III/IV CKD, evaluating the potential correlation of complement fragments with brachial artery flow-mediated dilation, Chronic Kidney Disease Epidemiology Collaboration glomerular filtration rate, and urinary albumin/creatinine ratio. Endothelial microparticles were characterized via proteomic analysis and compared between study groups. Complement fragment Ba was significantly increased in CKD and post-kidney transplant CKD. Plasma Ba levels correlated significantly with lower brachial artery flow-mediated dilation, lower Chronic Kidney Disease Epidemiology Collaboration glomerular filtration rate, and higher urinary albumin/creatinine ratio. Factor D levels were significantly higher in the plasma microparticles of patients with CKD versus healthy controls. Plasma microparticles isolated from patients with CKD and containing factor D activated the alternative pathway in vitro. CONCLUSION: The alternative complement pathway is activated in CKD and correlates with endothelial dysfunction and markers of CKD. Future studies are needed to evaluate whether endothelial microparticles with increased factor D play a pathologic role in CKD-associated vascular disease. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02230202.

Effects of a Carob-Pod-Derived Sweetener on Glucose Metabolism.

BACKGROUND: Patients with type 2 diabetes mellitus (T2DM) have a higher incidence of cardiovascular (CV) events. The ingestion of high-glycemic index (GI) diets, specially sweetened beverage consumption, has been associated with the development of T2DM and CV disease. OBJECTIVE: We investigated the effects of the intake of a sweetened beverage, obtained from natural carbohydrates containing pinitol (PEB) compared to a sucrose-enriched beverage (SEB) in the context of impaired glucose tolerance (IGT) and diabetes. METHODS: The study was divided in three different phases: (1) a discovery phase where the plasma proteomic profile was investigated by 2-DE (two-dimensional electrophoresis) followed by mass spectrometry (matrix-assisted laser desorption/ionization time-of-flight-MALDI-TOF/TOF) in healthy and IGT volunteers; (2) a verification phase where the potential mechanisms behind the observed protein changes were investigated in the discovery cohort and in an additional group of T2DM volunteers; and (3) the results were validated in a proof-of-concept interventional study in an animal model of diabetic rats with complementary methodologies. RESULTS: Six weeks of pinitol-enriched beverage (PEB) intake induced a significant increase in two proteins involved in the insulin secretion pathway, insulin-like growth factor acid labile subunit (IGF1BP-ALS; 1.3-fold increase; P = 0.200) and complement C4A (1.83-fold increase; P = 0.007) in IGT subjects but not in healthy volunteers. Changes in C4A were also found in the serum samples of Zucker diabetic fatty (ZDF) rats after four weeks of PEB intake compared to basal levels (P = 0.042). In addition, an increased expression of the glucose transporter-2 (GLUT2) gene was observed in the jejunum (P = 0.003) of inositol-supplemented rats when compared to sucrose supplementation. This change was correlated with the observed change in C4A (P = 0.002). CONCLUSIONS: Our results suggest that the substitution of a common sugar source, such as sucrose, by a naturally-based, pinitol-enriched beverage induces changes in the insulin secretion pathway that could help to reduce blood glucose levels by protecting ß-cells and by stimulating the insulin secretion pathway. This mechanism of action could have a relevant role in the prevention of insulin resistance and diabetes progression.

Leishmania donovani Inhibitor of Serine Peptidases 2 Mediated Inhibition of Lectin Pathway and Upregulation of C5aR Signaling Promote Parasite Survival inside Host.

Leishmania donovani, the causative agent of Indian visceral leishmaniasis has to face several barriers of the immune system inside the mammalian host for its survival. The complement system is one of the first barriers and consists of a well-balanced network of proteases including S1A family serine proteases (SPs). Inhibitor of serine peptidases (ISPs) is considered as inhibitor of S1A family serine peptidases and is reported to be present in trypanosomes, including Leishmania. In our previous study, we have deciphered the role of ISPs [LdISP1 and L. donovani inhibitor of serine peptidases 2 (LdISP2)] in the survival of L. donovani inside the sandfly midgut. However, the role of theses ISPs in the survival of L. donovani inside mammalian host still remains elusive. In the present study, we have deciphered the inhibitory effect of LdISPs on the host complement S1A serine peptidases, such as C1r/C1s and MASP1/MASP2. Our study suggested that although both rLdISP1 and rLdISP2 inferred strong interaction with C1complex and MBL-associated serine proteases (MASPs) but rLdISP2 showed the stronger inhibitory effect on MASP2 than rLdISP1. Moreover, we found that rLdISP2 significantly reduces the formation of C3, C5 convertase, and membrane attacking complex (MAC) by lectin pathway (LP) resulting in significant reduction in serum mediated lysis of the parasites. The role of LdISP2 on neutrophil elastase-mediated C5aR signaling was also evaluated. Notably, our results showed that infection of macrophages with ISP2-overexpressed Leishmania parasites significantly induces the expression of C5aR both at the transcript and translational level. Simultaneously, infection with ISP2KD parasites results in downregulation of host PI3K/AKT phosphorylation and increased in IL-12 production. Taken together, our findings clearly suggest that LdISP2 promotes parasite survival inside host by inhibiting MAC formation and complement-mediated lysis via LP and by upregulation of C5aR signaling.

Genetically predicted complement component 4A expression: effects on memory function and middle temporal lobe activation.

BACKGROUND: The longstanding association between the major histocompatibility complex (MHC) locus and schizophrenia (SZ) risk has recently been accounted for, partially, by structural variation at the complement component 4 (C4) gene. This structural variation generates varying levels of C4 RNA expression, and genetic information from the MHC region can now be used to predict C4 RNA expression in the brain. Increased predicted C4A RNA expression is associated with the risk of SZ, and C4 is reported to influence synaptic pruning in animal models. METHODS: Based on our previous studies associating MHC SZ risk variants with poorer memory performance, we tested whether increased predicted C4A RNA expression was associated with reduced memory function in a large (n = 1238) dataset of psychosis cases and healthy participants, and with altered task-dependent cortical activation in a subset of these samples. RESULTS: We observed that increased predicted C4A RNA expression predicted poorer performance on measures of memory recall (p = 0.016, corrected). Furthermore, in healthy participants, we found that increased predicted C4A RNA expression was associated with a pattern of reduced cortical activity in middle temporal cortex during a measure of visual processing (p < 0.05, corrected). CONCLUSIONS: These data suggest that the effects of C4 on cognition were observable at both a cortical and behavioural level, and may represent one mechanism by which illness risk is mediated. As such, deficits in learning and memory may represent a therapeutic target for new molecular developments aimed at altering C4's developmental role.

Complement-activation fragment C4a mediates effector functions by binding as untethered agonist to protease-activated receptors 1 and 4.

C4a is a small protein released from complement component C4 upon activation of the complement system's classical and lectin pathways, which are important constituents of innate immune surveillance. Despite the structural similarity between C4a and well-described anaphylatoxins C3a and C5a, the binding partner and biological function of C4a have remained elusive. Using a cell-based reporter assay, we screened C4a against a panel of both known and orphan G protein-coupled receptors and now provide evidence that C4a is a ligand for protease-activated receptor (PAR)1 and PAR4. Whereas C4a showed no activity toward known anaphylatoxin receptors, it acted as an agonist for both PAR1 and PAR4 with nanomolar activity. In human endothelial cells, ERK activation by C4a was mediated through both PAR1 and PAR4 in a Gαi-independent signaling pathway. Like other PAR1 activators, C4a induced calcium mobilization through the PAR1/Gαq/PLCß signaling axis. Moreover, C4a increased stress fiber formation and enhanced endothelial permeability, both of which were reduced by PAR1 antagonists. In sum, our study identifies C4a as an untethered agonist for PAR1 and PAR4 with effects on cellular activation and endothelial permeability, thereby revealing another instance of cross-talk between the complement system and other host defense pathways.

The complement system: a gateway to gene-environment interactions in schizophrenia pathogenesis.

The pathogenesis of schizophrenia is considered to be multi-factorial, with likely gene-environment interactions (GEI). Genetic and environmental risk factors are being identified with increasing frequency, yet their very number vastly increases the scope of possible GEI, making it difficult to identify them with certainty. Accumulating evidence suggests a dysregulated complement pathway among the pathogenic processes of schizophrenia. The complement pathway mediates innate and acquired immunity, and its activation drives the removal of damaged cells, autoantigens and environmentally derived antigens. Abnormalities in complement functions occur in many infectious and autoimmune disorders that have been linked to schizophrenia. Many older reports indicate altered serum complement activity in schizophrenia, though the data are inconclusive. Compellingly, recent genome-wide association studies suggest repeat polymorphisms incorporating the complement 4A (C4A) and 4B (C4B) genes as risk factors for schizophrenia. The C4A/C4B genetic associations have re-ignited interest not only in inflammation-related models for schizophrenia pathogenesis, but also in neurodevelopmental theories, because rodent models indicate a role for complement proteins in synaptic pruning and neurodevelopment. Thus, the complement system could be used as one of the 'staging posts' for a variety of focused studies of schizophrenia pathogenesis. They include GEI studies of the C4A/C4B repeat polymorphisms in relation to inflammation-related or infectious processes, animal model studies and tests of hypotheses linked to autoimmune diseases that can co-segregate with schizophrenia. If they can be replicated, such studies would vastly improve our understanding of pathogenic processes in schizophrenia through GEI analyses and open new avenues for therapy.

Comparative proteome analysis for identification of differentially abundant proteins in SIDS.

Sudden infant death syndrome (SIDS) remains one of the most common causes of post-neonatal infant mortality in developed countries. Its pathogenesis is still poorly understood. The goal of the present study was to characterize changes in the proteome of SIDS compared to age-matched controls in heart and medulla tissues as well as in blood samples using two complementary quantitative proteomic techniques: 2D-DIGE and iTRAQ aiming to provide new insights into the mechanism of SIDS and to find diagnostic protein patterns. Our results revealed collectively 122 modulated proteins in SIDS of which 83 proteins were up-regulated. They are involved in metabolic processes, cellular processes, and localization. Gene expression patterns of selected proteins were further validated by reverse transcription quantitative real-time PCR (RT-qPCR). The role of hypoxia, inflammation, and apoptosis in SIDS was demonstrated by exploring some candidate proteins especially APOA1, GAPDH, S100B, zyxin, and complement component C4A. According to the results of this study, these proteins might be used as diagnostic biomarkers for SIDS. All of them were up-regulated in SIDS except for C4A that was down-regulated.

Presence of retinal pericyte-reactive autoantibodies in diabetic retinopathy patients.

The loss of retinal pericytes (RPCs) is a hallmark of early stage diabetic retinopathy (DR), but the mechanism underlying RPC death is unclear. Although it was postulated in previous studies using bovine RPCs that autoantibodies against RPCs might develop and induce RPC death, it is unknown whether autoantibodies against cell-surface antigens on human RPCs exist in DR patients, whether such autoantibodies contribute to RPC damage/loss, and if they do, through which mechanism. We screened serum samples from DR patients and controls using primary human RPCs and found that that levels of IgGs reactive to RPCs were significantly higher in the DR group than the control group. Serum samples with higher RPC-reactive IgG levels induced more severe complement-mediated RPC damage than those with lower RPC-reactive IgG levels. We also assessed levels of the complement-activation products C3a, C4a and C5a in these serum samples, and found that serum levels of C3a and C5a, but not C4a, were higher in the DR group than control group. These data provide evidence the first time showing that autoantibodies against RPCs can develop in DR patients, and that these autoantibodies could contribute to pericyte damage through complement activation.

Protective effect of C4a against hyperoxic lung injury via a macrophage-dependent but not a neutrophil/lymphocyte-dependent signaling pathway.

Complement anaphylatoxins have been investigated extensively; however, the role of complement anaphylatoxin C4a in hyperoxic lung injury has yet to be investigated. To the best of our knowledge, the present study is the first to demonstrate the role of C4a in hyperoxic lung injury in vitro and in vivo. BALB/c mice were ventilated with 100% oxygen with or without C4a treatment for 36 h. The body weight and the relative lung weight of the mice were determined, along with any morphological changes in the lung. The expression levels of interleukin (IL)-1, IL-6 and tumor necrosis factor-α (TNF-α) were quantified in the lung tissue and bronchoalveolar lavage fluid (BALF) samples by enzyme-linked immunosorbent assay (ELISA) and western blot analysis. The total cell count and the number of macrophages, neutrophils and lymphocytes in the BALF were determined using cytocentrifuge slides and a hemocytometer. Histamine release from total cells in the BALF was also analyzed. The relative mRNA expression levels of CD68, F4/80, CD64, CD19 and CD3 in the murine lung tissue were assessed by reverse transcription-quantitative polymerase chain reaction. The results revealed that hyperoxia induced lung injury and morphological changes, and increased the expression levels of IL-1, IL-6 and TNF-α, histamine release, the number of inflammatory cells, and the expression levels of CD68, F4/80, CD64, CD19 and CD3. The hyperoxia-induced morphological changes and inflammatory reaction were significantly attenuated in mice treated with C4a. Treatment with C4a also attenuated the increase in the total cell count, decreased the number of macrophages in the BALF, and suppressed the elevated mRNA expression levels of CD68 and F4/80 in the lung tissue samples. Conversely, treatment with C4a did not affect the number of neutrophils or lymphocytes in the BALF or the mRNA expression of CD64, CD19 and CD3 in lung tissue. In conclusion, C4a attenuated hyperoxic lung injury via a macrophage-dependent but not a neutrophil/lymphocyte-dependent pathway.

Activation of the lectin pathway of complement by cardiopulmonary bypass contributes to the development of systemic inflammatory response syndrome after paediatric cardiac surgery.

The systemic inflammatory response is a challenge in the management of paediatric patients undergoing cardiac surgery. Although multi-factorial, a contribution by the lectin pathway of complement activation has been postulated. We therefore investigated the changes in serum levels of mannose binding lectin (MBL) and activities of MBL-MBL-associated serine protease (MASP)-1 and MBL-MASP-2 complexes immediately before and during surgery, throughout the first postoperative day and at discharge from the hospital. These changes were analysed in relation to postoperative complications. Blood samples were obtained from 185 children with congenital heart disease undergoing surgical correction with the use of cardiopulmonary bypass: preoperatively (MBL-1), 15 min after initiation of cardiopulmonary bypass (CPB) (MBL-E), 30 min (MBL-2), 4 h (MBL-3), 12 h (MBL-4) and 24 h (MBL-5) post-CPB and at discharge from hospital (MBL-K). Alterations in serum MBL levels were calculated as a ratio of its serum level at subsequent time-points (MBL-2, -3, -4, -5) to the preoperative (MBL-1) value. Decreases in MBL and MBL-MASP complexes were observed in all samples, correlating with a decrease in C4 and increase in C4a, confirming activation of the lectin pathway. Changes in MBL levels between children with an uncomplicated postoperative course and those suffering from infection or low cardiac output syndrome did not differ significantly, but significant differences were observed between the SIRS and non-SIRS groups. Paediatric cardiac surgery with the use of cardiopulmonary bypass activates the complement system via the lectin pathway and the latter contributes to the development of the post-bypass systemic inflammatory response.

CD66b Overexpression and Loss of C5a Receptors as Surface Markers for Staphylococcus aureus-Induced Neutrophil Dysfunction.

Neutrophil granulocytes constitute the main component of innate immunity in the clearance of bacterial infections. However, during systemic inflammation, immunoparalysis may occur resulting in neutrophil dysfunction. This study presents a new in vitro model for analyzing the dysfunction of human peripheral blood neutrophils resulting from the interaction with Staphylococcus aureus components in whole blood. After induction of a massive complement activation by S. aureus supernatant, the neutrophils exhibit a reduced phagocytic capacity resulting in a dramatic reduction of the antibacterial activity similar to that of neutrophils isolated from septic patients. The number of phagocytozing neutrophils is drastically reduced as well as the phagocytic capacity designated by a significantly lower number of ingested microbes. This dysfunction correlates with the loss of complement component 5a receptor 1 from the neutrophil cell surface and can be further characterized by a C5a-induced CD66b overexpression. The presented in vitro model offers a new platform for preclinical testing of immunosuppressive drugs and delivers new information for the understanding of neutrophil dysfunctions under the conditions described.

Complement C4a inhibits the secretion of hepatitis B virus screened by surface-enhanced laser desorption ionization time-flight mass spectrometry-based ProteinChip analysis.

PURPOSE: Chronic hepatitis B (CHB) is a kind of chronic liver disease caused by persistent hepatitis B virus (HBV) infection. The study aims to seek the factors of host resistance to HBV and investigate their roles. EXPERIMENTAL DESIGN: Protein profiles of 58 healthy controls and 121 CHB patients were obtained by SELDI-TOF/MS. Predicted protein was validated by ELISA. Protein expression was evaluated by Western blot in the persistently HBV expressing cell line HepG2.2.15 and non-HBV expressing cell line HepG2. The level of HBV DNA was subsequently detected by quantitative real-time PCR in HepG2.2.15 cells with complement C4a treatment. RESULTS: Significantly altered protein peaks were found through statistical analysis, and m/z 4300 was predicted by databases and successfully matched with the fragment of complement C4a. According to ELISA, serum complement C4a was found to be significantly lower in CHB patients compared with healthy controls (p < 0.001) and the area under receiver operating characteristics curve is 0.78. Furthermore, complement C4a showed lower expression in HepG2.2.5 cells and the secretion of HBV DNA was inhibited by complement C4a. CONCLUSIONS AND CLINICAL RELEVANCE: The present study implied the important role of complement C4a in inhibiting the HBV DNA secretion in CHB.

Complement anaphylatoxin C4a inhibits C5a-induced neointima formation following arterial injury.

Interactions between complement anaphylatoxins have been investigated in numerous fields; however, their functions during arterial remodeling following injury have not been studied. The inhibitory effect of complement anaphylatoxin C4a on neointima formation induced by C5a following arterial injury was investigated. Mice were subjected to wire-induced endothelial denudation of the femoral artery and treated with C5a alone or C5a + C4a for two weeks. C4a significantly inhibited C5a-induced neointima formation and the expression of CD68, F4/80, tumor necrosis factor-α (TNF­α), interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1). In vitro, although C4a did not directly inhibit the migration, proliferation or the expression of vascular cell adhesion molecule-1 (VCAM-1) of C5a-induced vascular smooth muscle cells (VSMCs), C5a-pretreated conditioned medium­induced migration, proliferation and VCAM-1 expression of VSMCs were suppressed when VSMCs were exposed to conditioned medium from C4a-pretreated macrophages. In addition, C5a-induced TNF-α, IL-6 and MCP-1 expression, Ca2+ influx and extracellular signal-regulated kinase (ERK) activation in macrophages were suppressed by C4a. C4a inhibits C5a-induced neointima formation, not by acting directly on VSMCs, but via a macrophage-mediated reaction by inhibiting the Ca2+-dependent ERK pathway in macrophages.

Copy number variations of complement component C4 are associated with Behçet's disease but not with ankylosing spondylitis associated with acute anterior uveitis.

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.

Predicting metachronous liver metastasis from colorectal cancer using serum proteomic fingerprinting.

BACKGROUND: There are currently no accurate predictive markers of metachronous liver metastasis (MLM) from colorectal cancer. METHODS: Magnetic bead-based fractionation coupled with mass spectrometry analysis was used to compare serum samples from 64 patients with MLM and 64 without recurrence or metastasis for at least 3 y after radical colorectal surgery (NM). A total of 40 MLM and 40 NM serum samples were randomly selected to build a decision tree, and the remainder were tested as blinded samples. Selected peptides were identified. RESULTS: The patients in the two groups were matched for gender, age, tumor location, TNM staging, and histologic differentiation grade. Preoperative serum carcinoembryonic antigen retained no independent power to predict MLM. The decision tree model with eight proteomic features (m/z 3315, 6637, 1207, 1466, 4167, 4210, 2660, and 4186) correctly classified 33 of 40 NM sera (82.5%) and 32 of 40 MLM sera (80%) in the training set and 19 of 24 NM sera (79.2%) and 17 of 24 MLM sera (70.8%) in the test set. The peptides were identified as fragments of alpha-fetoprotein, complement C4-A, fibrinogen alpha, eukaryotic peptide chain release factor GTP-binding subunit ERF3B, and angiotensinogen. CONCLUSIONS: In patients matched for gender, age, tumor location, TNM staging, and histologic differentiation grade, preoperative carcinoembryonic antigen retained no independent power to predict MLM. The decision tree model of eight proteomic features demonstrated promising value for predicting MLM in patients who underwent radical resection of colorectal cancer.

Correlation of serum levels of complement C4a desArg with pathologically estimated severity of glomerular lesions and mesangial hypercellularity scores in patients with IgA nephropathy.

The aim of the present study was to explore serum biomarkers for the pathology of IgA nephropathy using serum proteomics. The subjects were 57 patients with IgA nephropathy who were divided into two groups (group 1, n=25; group 2, n=32) and 14 healthy controls. Serum protein profiles were analyzed using the ProteinChip surface-enhanced laser desorption ionization (SELDI) system. Associations between signal intensities of proteins and histological findings in patients with IgA nephropathy were studied in group 1. Serum levels of a candidate biomarker protein (complement component C4a desArg) for IgA nephropathy were determined by enzyme linked-immunosorbent assay (ELISA) in group 2 and the relationships of these levels with histological findings were evaluated. There were significant differences in 93 protein signals between patients in group 1 and controls. Among these signals, 3 proteins at 8592, 8757 and 8806 m/z were significantly correlated with the severity of glomerular lesions. The protein at 8592 m/z was identified as C4a desArg and the signal intensity of 8592 m/z was strongly correlated with serum C4a levels, including C4a desArg, determined by ELISA. In addition, the serum levels of C4a (mainly C4a desArg) were significantly higher in patients in group 2 compared to controls and were correlated with the severity of glomerular lesions and with mesangial hypercellularity scores. In conclusion, the serum levels of complement C4a desArg are significantly higher in patients with IgA nephropathy compared to healthy controls and are significantly correlated with the severity of glomerular lesions and mesangial hypercellularity scores. Thus, serum C4a desArg is a potential biomarker for the severity of histological findings in patients with IgA nephropathy.