A complement C4-derived glycopeptide is a biomarker for PMM2-CDG

BACKGROUNDDiagnosis of PMM2-CDG, the most common congenital disorder of glycosylation (CDG), relies on measuring carbohydrate-deficient transferrin (CDT) and genetic testing. CDT tests have false negatives and may normalize with age. Site-specific changes in protein N-glycosylation have not been reported in sera in PMM2-CDG.METHODSUsing multistep mass spectrometry-based N-glycoproteomics, we analyzed sera from 72 individuals to discover and validate glycopeptide alterations. We performed comprehensive tandem mass tag-based discovery experiments in well-characterized patients and controls. Next, we developed a method for rapid profiling of additional samples. Finally, targeted mass spectrometry was used for validation in an independent set of samples in a blinded fashion.RESULTSOf the 3,342 N-glycopeptides identified, patients exhibited decrease in complex-type N-glycans and increase in truncated, mannose-rich, and hybrid species. We identified a glycopeptide from complement C4 carrying the glycan Man5GlcNAc2, which was not detected in controls, in 5 patients with normal CDT results, including 1 after liver transplant and 2 with a known genetic variant associated with mild disease, indicating greater sensitivity than CDT. It was detected by targeted analysis in 2 individuals with variants of uncertain significance in PMM2.CONCLUSIONComplement C4-derived Man5GlcNAc2 glycopeptide could be a biomarker for accurate diagnosis and therapeutic monitoring of patients with PMM2-CDG and other CDGs.FUNDINGU54NS115198 (Frontiers in Congenital Disorders of Glycosylation: NINDS; NCATS; Eunice Kennedy Shriver NICHD; Rare Disorders Consortium Disease Network); K08NS118119 (NINDS); Minnesota Partnership for Biotechnology and Medical Genomics; Rocket Fund; R01DK099551 (NIDDK); Mayo Clinic DERIVE Office; Mayo Clinic Center for Biomedical Discovery; IA/CRC/20/1/600002 (Center for Rare Disease Diagnosis, Research and Training; DBT/Wellcome Trust India Alliance).

[Magnetic resonance imaging T2 mapping could reflect disease status in patients with dermatomyositis or polymyositis]

This study aimed to explore the value of magnetic resonance imaging (MRI) T2 mapping in the assessment of dermatomyositis (DM) and polymyositis (PM). Thirty-three confirmed cases (myosin group) and eight healthy volunteers (healthy control group) at the Department of Rheumatology and Immunology, the First Affiliated Hospital of Kunming Medical University, from October 2016 to December 2017, were collected and analyzed. Multiple parameters of the myosin group were quantified, including creatine kinase (CK), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), complement C3, and complement C4. Disease status was evaluated using a panel of tools: myositis disease activity assessment tool-muscle (MDAAT-muscle), myositis disease activity assessment tool-whole (MDAAT-all), health assessment questionnaire (HAQ), medical outcomes study health survey short form-36 item (SF-36), hand muscle strength test (MMT-8) score, and MRI T2 mapping of muscle (22 muscles in the pelvis and thighs) T2 values. The results showed that in the myositis group, the measurements for CK, ESR, CRP, complement C3, and complement C4 were 457.2 (165.6, 1 229.2) IU/L, 20 (10, 42) mm/1h, 3.25 (2.38, 10.07) mg/L, 0.90 (0.83, 1.06) g/L, and 0.18 (0.14, 0.23) g/L, respectively. The scores for MMT-8, MDAAT-muscle, MDAAT-all, HAQ, and SF-36 were 57.12±16.23, 5.34 (4.00, 6.00), 34.63±12.62, 1.55 (0.66, 2.59), and 44.66±7.98, respectively. T2 values were significantly higher in all 22 muscles of the pelvis and thighs of patients with DM or PM compared with the healthy controls [(54.99±11.60)ms vs. (36.62±1.66)ms, P<0.001], with the most severe lesions in the satrorius, iliopsoas, piriformis, gluteus minimus, and gluteus medius muscles. The total muscle T2 value in the myositis group was positively correlated with CK, MDAAT-muscle, MDAAT-all, and HAQ (r=0.461, 0.506, 0.347, and 0.510, respectively, all P<0.05). There was a negative correlation between complement C4, SF-36, and MMT-8 scores (r=-0.424, -0.549, and -0.686, respectively, all P<0.05). Collectively, the findings from this study suggest that MRI T2 mapping can objectively reflect the disease status of DM and PM.

Renin-angiotensin-aldosterone-system inhibitors increase the serum level of complement component 4 in patients with immunoglobulin A nephropathy

OBJECTIVE

To investigate the impact of renin-angiotensin-aldosterone-system (RAAS) inhibitors on complement component 4 (C4) serum levels in patients with immunoglobulin A nephropathy (IgAN).

METHODS

A total of 423 patients diagnosed with IgAN at Shanxi Provincial People's Hospital, China, between 1 January 2017 and 31 December 2021 were divided into two groups, a RAAS inhibitor group and a non-RAAS inhibitor group, for comparative analysis.

RESULTS

The RAAS inhibitor group exhibited significantly increased C4 and eGFR levels and had a higher proportion of patients with hypertension compared with the non-RAAS inhibitor group. Serum C4 levels were positively correlated with 24-hour urine protein, serum C3 levels and blood uric acid levels but negatively correlated with eGFR levels. In addition, serum C4 levels were positively correlated with the severity of mesangial hypercellularity and interstitial/tubular injury. Through prognostic analysis, serum C4 was identified as an independent risk factor for the progression of IgAN.

CONCLUSION

Renin-angiotensin-aldosterone-system inhibitors can increase serum C4 levels in patients with IgAN and may represent an independent risk factor for disease progression.

Complement

The role of complement in human autoimmune, inflammatory, and infectious diseases is reviewed, focusing on clinical applicability. A typical case is presented in which serum testing for C3 and C4 is performed to help assess a syndrome with a broad differential diagnosis. The review includes a discussion of complement deficiency states, consumption of complement by diseases characterized by immune-complex formation and deposition, usefulness and interpretation of laboratory tests for complement, and development of drugs targeting specific components of the complement pathway for a growing number of indications.

Elevated Layilin-Positive Monocyte Levels in the Peripheral Blood of Patients with Systemic Lupus Erythematosus Reflect Their Autoimmune Status

OBJECTIVE

To investigate the expression of layilin (LAYN) in human circulating monocytes and lymphocytes and its clinical significance in systemic lupus erythematosus (SLE).

METHODS

Blood samples were collected from 51 SLE patients and 50 healthy controls. Flow cytometry was used to analyze LAYN in lymphocytes and monocyte subsets. Functionally characterized molecules including human HLA, CD74 and CD62L were studied in LAYN+ monocytes. A correlation analysis was conducted between LAYN-related subsets and clinical indicators of SLE such as anti-double-stranded DNA and complements levels. ROC curves were used to explore the potential clinical diagnostic value of LAYN in SLE.

RESULTS

LAYN was significantly higher in monocytes than in lymphocytes and higher in CD14+CD16+ monocytes than in CD14-CD16+ and CD14+CD16- monocytes. CD74 was upregulated and CD62L was downregulated in LAYN+ monocytes compared with LAYN- monocytes. The absolute number of LAYN+ monocytes was increased in SLE patients, and the median fluorescence intensity of HLA was decreased. LAYN+ monocytes were positively correlated with complement C4, while decreased CD62L+ percentages in LAYN+ monocytes were negatively correlated with C4. The ROC analysis revealed that the area under the curve (AUCs) for CD62L+ percentages in LAYN+ monocytes, LAYN+ lymphocyte numbers, and LAYN+ monocyte numbers to distinguish SLE from healthy individuals were 0.6245, 0.6196 and 0.6173, respectively.

CONCLUSION

LAYN is differentially expressed in monocytes and their subpopulations and has corresponding functional differences. Changes in LAYN expression on monocytes are associated with complement C4 levels in SLE patients. These suggest that LAYN may be involved in the pathogenesis of SLE.

ABBREVIATION

ANOVA: analysis of variance; anti-dsDNA: anti-double-stranded DNA; anti-ENA: anti-extractable nuclear antigen; anti-SSA: anti-Sjogren syndrome A; anti-SSB: anti-Sjogren syndrome B; anti-U1RNP: anti-U1 ribonucleoprotein; AUC: area under the ROC curve; CBC: complete blood count; CD62L: L-selectin; CD74/Ii: MHC class II invariant chain; CD44/HCAM: homing cell adhesion molecule; cMos: classical monocytes; CRP: C-reactive protein; CXCR2: C-X-C motif chemokine receptor 2; CXCR4: C-X-C motif chemokine receptor 4; ESR: erythrocyte sedimentation rate; HCs: healthy controls; HA: hyaluronan; HLA: human leukocyte antigen; Ig: immunoglobulin; iMos: intermediate monocytes; LAYN: layilin; MFI: median fluorescence intensity; MIF: migration inhibitory factor; ncMos: nonclassical monocytes; PBMCs: peripheral blood mononuclear cells; ROC: receiver operating characteristic curve; SLE: systemic lupus erythematosus; SLEDAI, SLE disease activity index; Treg: regulatory T cells; WBCs: white blood cells.

[Risk factors associated with different types of Henoch-Schönlein purpura in Tibetan patients at high altitude]

OBJECTIVE

To investigate the risk factors of different types of Henoch-Schönlein purpura (HSP) in Tibetan patients at high altitude, as to provide reference for correctly identifying high-risk patients.

METHODS

A retrospective study was used to analyze the 304 HSP patients admitted to Tibet Autonomous Region People's Hospital from April 2014 to March 2022. The gender, age, allergic history, family history, clinical type, laboratory indexes (hemoglobin, platelet count, eosinophil, C-reactive protein (CRP), albumin, immunoglobulin G, immunoglobulin A, complement C3 and C4) were analyzed retrospectively. Univariate and multivariate Logistic regression analysis to screen for risk factors affecting different types of HSP.

RESULTS

Renal HSP patients showed higher IgA [(9.2±1.7) g/L vs. (6.4±2.4) g/L, P=0.015], lower complement C3 [(203.3±21.6) mg/dL vs. (301.1±19.5) mg/dL, P=0.043], and complement C4 [(33.5±2.3) mg/dL vs. (53.0±7.2) mg/dL, P=0.032]. The patients with abdominal HSP showed lower levels of hemoglobin [(119.6±19.6) g/L vs. (146.6±47.3) g/L, P=0.038] and plasma albumin [24.8 (22.1, 33.9) g/L vs. 32.6 (24.6, 35.1) g/L, P=0.045]. The patients with articular HSP exhibited higher CRP [13.5 (0.2, 20.6) g/L vs. 7.5 (0.1, 15.2) g/L, P=0.036] and erythrocyte sedimentation rate (ESR) [24 (5, 40) mm/h vs. 15 (4, 30) mm/h, P=0.049]. Elevated IgA and decreased complement C4 were risk factors for renal HSP, anemia and decreased plasma albumin were risk factors for abdominal HSP, and elevated CRP was a risk factor for articular HSP.

CONCLUSION

The clinical characteristics of different types of HSP in plateau areas were different. Patients with high IgA, low complement C4, anemia, hypoalbuminemia, and significantly elevated CRP should be highly vigilant. Early and effective intervention can improve the clinical efficacy, avoid severe development, and improve the prognosis.

Rare manifestations of cryoglobulinemic vasculitis: a case report

Introduction

Cryoglobulinemic vasculitis is a type of small vessel vasculitis diseases that can cause dysfunction in multiple organs. It is characterized by general symptoms, often accompanied by nonspecific cutaneous, articular, neurological, and renal manifestations. Diagnosing cryoglobulinemia through biological testing can be time-consuming and sometimes yields negative results, making diagnosis challenging. There are also other potentially life-threatening complications that can significantly impact prognosis and delay urgent treatment, including digestive manifestations and heart failure.

Case presentation

We report the case of a 60-year-old male patient with a medical history of rheumatoid arthritis. He was admitted to the Nephrology Department for investigation of necrotic vascular purpura, acute kidney injury, and pancytopenia. Laboratory tests revealed consumption of the C3 and C4 complement fractions and the presence of mixed-type III cryoglobulinemia. Despite the initiation of the treatment, the patient rapidly developed multiple severe organ failures, including renal, cardiac, respiratory, and finally digestive complications. Acute colic ischemia led to emergency surgery and the patient was transferred to the Intensive Care Unit. Despite surgical intervention and hemodynamic support, the patient experienced multi-visceral organ failure and died two hours after admission.

Discussion

Mixed cryoglobulinemia vasculitis may result in rare cases of acute and life-threatening organ damage, such as cardiac or respiratory failure with pulmonary hemorrhage, gastrointestinal ischemia, and neurological disorders. These severe manifestations are associated with a poor prognosis and it is crucial to promptly initiate an aggressive therapeutic strategy.

Serum levels of fibrogenesis biomarkers reveal distinct endotypes predictive of response to weight loss in advanced nonalcoholic fatty liver disease

BACKGROUND

NAFLD is associated with activation of fibroblasts and hepatic fibrosis. Substantial patient heterogeneity exists, so it remains challenging to risk-stratify patients. We hypothesized that the amount of fibroblast activity, as assessed by circulating biomarkers of collagen formation, can define a "high-risk, high-fibrogenesis" patient endotype that exhibits greater fibroblast activity and potentially more progressive disease, and this endotype may be more amendable to dietary intervention.

METHODS

Patients with clinically confirmed advanced NAFLD were prescribed a very low-calorie diet (VLCD) intervention (∼800 kcal/d) to induce weight loss, achieved using total diet replacement. Serum markers of type III (PRO-C3) and IV collagen (PRO-C4) fibrogenesis were assessed at baseline every second week until the end of the VLCD, and 4 weeks post-VLCD and at 9 months follow-up.

RESULTS

Twenty-six subjects had a mean weight loss of 9.7% with VLCD. This was associated with significant improvements in liver biochemistry. When stratified by baseline PRO-C3 and PRO-C4 into distinct fibrosis endotypes, these predicted substantial differences in collagen fibrogenesis marker dynamics in response to VLCD. Patients in the high activity group (PRO-C3 >11.4 ng/mL and/or PRO-C4 >236.5 ng/mL) exhibited a marked reduction of collagen fibrogenesis, ranging from a 40%-55% decrease in PRO-C3 and PRO-C4, while fibrogenesis remained unchanged in the low activity group. The biochemical response to weight loss was substantially greater in patients a priori exhibiting a high fibroblast activity endotype in contrast to patients with low activity.

CONCLUSIONS

Thus, the likelihood of treatment response may be predicted at baseline by quantification of fibrogenesis biomarkers.

A novel model predicted liver cirrhosis constructed by ultrasound and serological in autoimmune liver hepatitis

To establish a noninvasive model based on two-dimensional shear wave elasticity (2D-SWE) technology, ultrasound feature and serological indicators to predict cirrhosis in autoimmune hepatitis (AIH) and verified. Patients with AIH confirmed by liver biopsy with liver ultrasound and serological examination were collected from January 2019 to May 2022. Patients were divided into cirrhosis and non-cirrhosis groups. Basic indexes, ultrasound indexes and serological indexes were collected. Multivariable logistic regression used for screening independent risk factors predicting cirrhosis, construct the AIH cirrhosis prediction model, named autoimmune hepatitis cirrhosis (AIHC). Determine best cutoff score according to the Youden index, verified the model's predictive efficacy. One hundred forty-six patients were collected. The following indicators were independent risk factors for predicting cirrhosis: LS (OR: 1.416, P = .015), splenomegaly (OR: 10.446, P = .006), complement C4 (OR: 0.020, P = .009). The best cutoff score was 65, with a sensitivity 88.9% and specificity 75.6%; the area under curve was 0.901, AIHC possessed a higher net reclassification index (NRI) and integrated discrimination improvement compared with other indexes, and AIHC had the best clinical decision curve. The AIHC constructed in this study has better predictive efficacy than other noninvasive indexes, and we visualized the model for easy application, which was worth further promotion in clinical practice.

Serum Complement C4 Levels Are a Useful Biomarker for Predicting End-Stage Renal Disease in Microscopic Polyangiitis

This study aimed to evaluate the risk factors for end-stage renal disease (ESRD) in microscopic polyangiitis (MPA). In total, 74 patients with MPA were enrolled, and we compared the baseline clinical characteristics and disease activity between MPA patients who have progressed to ESRD and those without ESRD to select predictive factors for ESRD. Out of 74 patients, 12 patients (16.2%) had ESRD during follow-up. Serum C4 levels were significantly higher in MPA patients who have progressed to ESRD than in those without ESRD (p = 0.009). Multivariate analyses revealed that high serum creatinine levels (odds ratio (OR) 4.4, 95% confidence interval (CI) 1.25-15.5) and high serum C4 levels (OR 1.24, 95% CI 1.03-1.49) were risk factors for ESRD. Using receiver operating characteristic analysis, the cut-off value for initial serum C4 levels and serum creatinine levels were 29.6 mg/dL and 3.54 mg/dL, respectively. Patients with MPA with a greater number of risk factors (serum C4 levels > 29.6 mg/dL and serum creatinine levels > 3.54 mg/dL) had a higher ESRD progression rate. Serum C4 levels were significantly positively correlated with serum creatinine levels and kidney Birmingham vasculitis activity score (p = 0.02 and 0.04, respectively). These results suggest that serum C4 levels are useful tools for assessing renal disease activity and prognosis in MPA.

Immunoglobulin A and complement C4 are involved in the progression of liver fibrosis in patients with chronic hepatitis B

OBJECTIVE

To explore the relationship between immunoglobulin A (IgA), complement C4, and liver fibrosis (L.F.) progression (LFP) in patients with chronic hepatitis B (CHB).

METHODS

This is a retrospective cohort study of CHB patients who received liver biopsies. Relevant data, including demographics, clinical serum markers, and immunological results obtained during liver biopsies, were collected and analyzed to assess and verify the relationship between IgA, C4, and LFP.

RESULTS

This study included 1,938 CHB patients, of whom 132 received two liver biopsies (group 1). Thirty (22.7%) of these patients were diagnosed with LFP (increase in L.F. stage (Scheuer score F ≥ 1)). IgA (C-IgA) and C4 (C-C4) change values between the first and second biopsies were independent risk factors for LFP. IgA levels increased, and C4 levels decreased during the second liver puncture. The remaining 1,806 patients received one liver puncture (group 2). They were divided into the following subgroups: A (F ≤ 1), B (1 < F ≤ 3), and C (F > 3) to verify whether the same trend was observed by cross-sectional study. IgA levels were highest, and C4 levels were lowest in group C (IgA: C > B > A, p < 0.05; C4: C < B < A, p < 0.05).

CONCLUSIONS

The findings of this study suggest that serum IgA and C4 levels are independent risk factors for LFP that could serve as future targets for L.F. management and treatment.

Extracellular matrix turnover biomarkers reflect pharmacodynamic effects and treatment response of adalimumab in patients with axial spondyloarthritis-results from two randomized controlled trials

OBJECTIVE

To investigate if extracellular matrix (ECM) blood-based biomarkers reflect the pharmacodynamic effect and response to TNF-α inhibitor therapy (adalimumab, ADA), in patients with axial spondyloarthritis (axSpA).

METHODS

We investigated ECM biomarkers in two randomized, double-blind, placebo-controlled trials of axSpA patients (DANISH and ASIM, n = 52 and n = 49, respectively) receiving ADA 40 mg or placebo every other week for 12 and 6 weeks, respectively, and thereafter ADA to week 48. Serum concentrations of degraded type I (C1M), II (C2M, T2CM), III (C3M), IV (C4M), VI (C6M), type X (C10C) collagen; metabolite of C-reactive protein (CRPM), prolargin (PROM), citrullinated vimentin (VICM), calprotectin (CPa9-HNE); and formation of type II (PRO‑C2), III (PRO‑C3), and VI (PRO‑C6) turnover of type IV collagen (PRO-C4) were measured at baseline and weeks 6 or 12, 24, and 48. The pharmacodynamic effect and treatment response to ADA was evaluated by linear mixed models, and correlations between biomarkers and clinical scores were assessed by Spearman's correlation.

RESULTS

C1M, C3M, C4M, C6M, CRP, PRO-C4, and CPa9-HNE levels declined after 6 or 12 weeks in patients receiving ADA compared to placebo (all p < 0.05). Patients with AS Disease Activity Score C-reactive protein (ASDAS CRP) major improvement and/or clinically important improvement had significantly higher C1M, C3M, C4M, C6M, and PRO-C4 levels than patients with no/low improvement at baseline (all p < 0.05). Baseline levels of biomarkers showed weak to moderate correlations with ASDAS and structural damage scores.

CONCLUSION

ECM metabolites showed a pharmacodynamic effect and were associated with ASDAS response during TNF-α inhibitor treatment in patients with axSpA.

Ethnic differences in complement system biomarkers and their association with metabolic health in men of Black African and White European ethnicity

Inflammation plays a fundamental role in the development of several metabolic diseases, including obesity and type 2 diabetes (T2D); the complement system has been implicated in their development. People of Black African (BA) ethnicity are disproportionately affected by T2D and other metabolic diseases but the impact of ethnicity on the complement system has not been explored. We investigated ethnic differences in complement biomarkers and activation status between men of BA and White European (WE) ethnicity and explored their association with parameters of metabolic health. We measured a panel of 15 complement components, regulators, and activation products in fasting plasma from 89 BA and 96 WE men. Ethnic differences were statistically validated. Association of complement biomarkers with metabolic health indices (BMI, waist circumference, insulin resistance, and HbA1c) were assessed in the groups. Plasma levels of the key complement components C3 and C4, the regulators clusterin and properdin and the activation marker iC3b were significantly higher in BA compared to WE men after age adjustment, while FD levels were significantly lower. C3 and C4 levels positively correlated with some or all markers of metabolic dysfunction in both ethnic groups while FD was inversely associated with HbA1c in both groups, and clusterin and properdin were inversely associated with some markers of metabolic dysfunction only in the WE group. Our findings of increased levels of complement components and activation products in BA compared to WE men suggest differences in complement regulation that may impact susceptibility to poor metabolic health.

Comparative analysis of complement C3 and C4 serum levels for outcome prediction in ANCA-associated renal vasculitis

BACKGROUND

The activation of the complement system contributes essentially to the pathogenesis of anti-neutrophil cytoplasmic antibody (ANCA)-associated renal vasculitis. We here aimed to directly compare levels of C3 and C4 for outcome prediction in ANCA-associated renal vasculitis.

METHODS

Serum levels of complement components C3 and C4 were directly compared in association with clinical and outcome data in a retrospective cohort of ANCA-associated renal vasculitis.

RESULTS

As compared to poor outcome prediction by low levels of complement C3 (p = 0.0093), low levels of complement C4 did not associate with early requirement of kidney replacement therapy (KRT) or death (p = 0.2396). In the subgroup that experienced KRT or death, low C3 levels identified 11/14 (78.6%, p = 0.0071) and C4 levels 9/14 (64.3%, p = 0.1786) cases. Interestingly, 2/14 (14.3%) patients that experienced KRT or death had isolated C4 lowering, and combining low C3 and/or C4 levels identified 13/14 (92.3%, p < 0.0001) cases in this subgroup. Non-superiority to predict poor outcome by low C3 and/or C4 as compared to C3 alone in the total cohort was attributed to 4/24 (16.7%) patients with isolated C4 lowering in the subgroup that did not experience KRT or death.

CONCLUSION

While low levels of complement C3 were superior in predicting poor outcome in ANCA-associated renal vasculitis, a minor fraction with poor outcome had isolated C4 lowering not captured by serum C3 measurements. Therefore, detailed knowledge of distinct complement components contributing to kidney injury could be of relevance to improve current strategies targeting the complement system in ANCA-associated renal vasculitis.

Cerebrospinal Fluid Complement 4 Levels Were Associated with Alzheimer's Disease Pathology and Cognition in Non-Demented Elderly

BACKGROUND

Numerous studies have shown that the complement system plays an important role in Alzheimer's disease (AD). However, whether complement 4 (C4) protein in cerebrospinal fluid (CSF) was associated with AD pathology, especially in the early stage of AD, is still unclear.

OBJECTIVE

We aimed to explore the association of CSF C4 with AD pathology and cognition in the preclinical AD.

METHODS

The study included a total of 287 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Based on the A/T scheme, they were divided into four groups to access the changes of CSF C4 in the preclinical AD. Linear regression models were used to test the associations between CSF C4 and AD core biomarkers, namely Aβ42, P-tau, and T-tau.

RESULTS

The level of CSF C4 decreased in the A + T- group compared with the A-T- group (p = 0.04) and it increased in the A-T+ group compared to the A + T- group (p = 0.01). In pooled samples, C4 was significantly associated with AD core biomarkers (all p < 0.05), but only in the A + group after stratification according to the A/T scheme. Furthermore, CSF C4 levels at baseline were associated with longitudinal cognitive changes.

CONCLUSIONS

Our results showed that CSF C4 levels changed dynamically in the preclinical AD, and that the responses of CSF C4 to brain Aβ pathology, tau pathology and neurodegeneration were found only in the presence of amyloid plaques, both of which indicates the complex link between C4 and AD.

Postinjury complement C4 activation is associated with adverse outcomes and is potentially influenced by plasma resuscitation

BACKGROUND

Complement activation after trauma promotes hemostasis but is associated with increased morbidity and mortality. However, the specific pathways and downstream mediators remain unclear. Recently, the anaphylatoxin C4a has been shown to bind to thrombin receptors. While plasma-based resuscitation has been shown to modify the endotheliopathy of trauma, it may provide complement zymogens that fuel ongoing inflammatory cascades. We sought to characterize the activation of complement after injury and the effect of fresh frozen plasma (FFP) on this inflammatory response. We hypothesized that trauma induces C4 activation, which is associated with worse outcomes and influenced by FFP resuscitation.

METHODS

Blood was collected from injured patients at a single level I trauma center enrolled in the Control of Major Bleeding after Trauma (COMBAT) randomized clinical trial. Proteomic analyses were performed through targeted liquid chromatography coupled with mass spectrometry. For the present observational study, concentrations of complement proteins were analyzed at multiple time points, compared between treatment groups, and correlated with outcomes.

RESULTS

C4 activation occurred over the first 6 hours postinjury with peak activation 6 to 24 hours. Tissue hypoperfusion, defined as base deficit >10 mEq/L, and requirement for massive transfusion were associated with greater C4 activation. C4 activation was associated with mortality, multiple organ failure, and longer ventilator requirement. In addition, temporal trends of C1q, factor B, and C3 by outcome groups support the prevailing theory of primary classical pathway activation with alternative pathway amplification. Resuscitation with FFP over the first 6 hours was associated with increased C4 activation at 12 and 24 hours.

CONCLUSION

C4 activation has an important inflammatory role postinjury, and FFP has the potential to augment this complement activation during resuscitation.

LEVEL OF EVIDENCE

Prognostic/epidemiological, level III.

[Diagnostic difficulties of IgG4-related disease - a case report]

IgG4-related disease belongs to the group of immune-mediated diseases. It is a relatively new condition, classified in 2003. It is characterized by involvement of multiple organs, over time causing organ failure. The observed radiological changes are slow growing. As a rule, the course of the disease is subclinical, which means that the diagnosis is often made incidentally, retrospectively and many years after the onset of symptoms. In the initial stage of diagnosis, it is often confused with Sjögren's syndrome, systemic vasculitis, or neoplastic disorders.

A CASE REPORT

We report the case of a female patient who was diagnosed with glomerulonephritis at the age of 34. The patient was qualified for renal replacement therapy with chronic hemodialyses in 2020 due to end-stage renal disease. In the same year, the patient was hospitalized for pneumonia of unknown etiology. After discharge from the hospital, the patient developed fever up to 39oC, chills, and pleural fluid. A suspicion of systemic disease was raised. Computed tomography of the chest showed enlargement of the anterior and middle mediastinum with increased densitization of adipose tissue and enlargement of mediastinal lymph nodes. Antibiotic therapy was introduced, followed by systemic corticosteroids, resulting in clinical improvement and remission of infiltrative lesions in radiological studies. The differential diagnosis excluded neoplastic lesions of the left lung, systemic connective tissue diseases, e.g. systemic lupus erythematosus and systemic vasculitis. Taking into account the whole clinical picture the suspicion of IgG4-related disease was raised. After the treatment, serum IgG4 level was found to be normal at 36.6 mg/ dl, anti-nuclear antibodies (ANA) were negative, rheumatoid factor was not elevated, complement component 4 (C4) was normal, complement component 3 (C3) decreased to 71 mg/dl (n: 90-180 mg/dl). Treatment with prednisone 10 mg/day was maintained. Histopathologic reanalysis of the renal biopsy (from a biopsy performed in 2012) was performed, which showed lymphocytic infiltration in the renal interstitium with segmental vascular loop sclerosis in the glomeruli and the presence of abundant granular IgG4 deposits in the glomerular mesangium by immunofluorescence.

CONCLUSIONS

IgG4-related disease poses great diagnostic difficulty due to its non-specific and long-term course. Patients usually seek help with various specialists many years before the full picture of the disease is presented. It is poorly understood as it is a recently described condition (two decades ago). The classification criteria of IgG4 disease developed in 2019, the growing number of publications and recommendations being developed give hope for better understanding and more efficient diagnosis of the disease.

Changes in physiological responses and immunity of blunt snout bream Megalobrama amblycephala from transport stress

This study aimed to investigate the effects of transport stress on the physiological responses and immunity of Megalobrama amblycephala (blunt snout bream). Fish (109.67 ± 1.51 g) were sampled at nine time points: before transport (control), at 0 h, 1 h, 3 h, 6 h, 12 h, 24 h, 3 days, and 7 days after 4 h of medium-distance transportation, and four fish were sampled in each time point. The results showed that plasma cortisol, triiodothyronine (T₃), complement component 3 (C3), complement component 4 (C4), immunoglobulin M (IgM) and nitrogen monoxide (NO) concentrations, and alternative complement pathway (ACH50), acid phosphatase (ACP), and myeloperoxidase (MPO) activities all reached the peak at 0 h after transportation; C4 and NO concentrations as well as ACP and MPO activities returned to the control level after 1 h, ACH50 activity as well as cortisol, T_3, and IgM concentration returned to the control level after 12 h, and C3 concentration returned to the control level after 24 h respectively. Plasma glucose and total protein concentrations as well as lysozyme activity all reached the peak at 1 h after transportation, total protein concentration and lysozyme activity returned to the control level after 3 h, and glucose concentration returned to the control level after 6 h (P < 0.05). Liver heat shock protein 70 expression reached the peak at 1 h after transportation, and returned to the control level after 24 h; liver heat shock protein 90 expression reached the peak at 0 h after transportation and returned to the control level after 12 h (P < 0.05). Overall, these findings suggested that 4 h of medium-distance transportation caused stress response of blunt snout bream, and transport stress had a significant effect on plasma indicators. But the recovery of 24 h after transport could return the physiological response, immune indexes, and the expression of heat shock protein to the normal level. This also provided data support for the medium-distance transportation of blunt snout bream in the future.

The Association Between Serum Complement 4 and Kidney Disease Progression in Idiopathic Membranous Nephropathy: A Multicenter Retrospective Cohort Study

Introduction

Complement system plays an important role in the pathogenesis of idiopathic membranous nephropathy (IMN), however, the relationship between serum complement 4 (C4) and kidney disease progression in IMN is unclear. This study aims to investigate the association of serum C4 level with the risk of kidney disease progression among patients with IMN.

Methods

The retrospective cohort assessed 1,254 participants with biopsy-proven IMN from three centers in Xi ‘an, Shaanxi Province, China. Baseline serum C4 levels were measured at renal biopsy. The association between baseline serum C4 and the risk of renal function progression, defined as a 30% decline in renal function or end stage renal disease, was evaluated in Cox proportional hazards models.

Results

A total of 328 patients with IMN and nephrotic proteinuria were eligible, and 11.3% (37/328) of them attained the renal function progression events after a median follow-up of 51 months (37-59 months). After adjustment for other confounders, a higher value of serum C4 was independently associated with a higher risk of renal function progression event with a hazard ratio (HR) of 4.76 (95% confidence interval [95% CI], 1.77-12.79) per natural log-transformed C4. In reference to the low level of C4, the adjusted HRs were 2.72 (95% CI, 1.02-7.24) and 3.65 (95% CI, 1.39-9.60), respectively, for the median and high levels of C4 (P for trend=0.008). Additionally, the results were robust and reliable in the sensitivity and subgroup analyses.

Conclusion

Among patients with IMN and nephrotic proteinuria, serum C4 at renal biopsy is an independent predictor for kidney disease progression regardless of other confounders.

Clinical impact of complement deposition findings on biopsies in acute rejection episodes of pediatric renal transplant patients

INTRODUCTION

Rejection is the most important problem for renal graft function and survival. Complement system plays a key role in immune responses from host to graft. It was demonstrated that complement system activation is related with renal fibrosis. We evaluate clinical impact of complement deposition findings on biopsies in acute rejection episodes of pediatric renal transplant patients.

METHOD

Demographics of the patients, graft functions, acute rejection episodes and graft loss were recorded from data files of 165 pediatric renal transplant patients. Findings of 98 renal biopsies were retrospectively evaluated.

RESULTS

Thirty three patients with kidney transplant had 44 acute rejection episodes (32 pure cellular acute rejection episodes / 1 pure humoral acute rejection episode / 11 combined acute cellular and acute humoral rejection episodes) proven by biopsy. C1q staining was positive in 7 biopsies, C3 staining in 15 biopsies and, C4d staining in 15 biopsies. 26 patients had graft fibrosis. All patients with a rejection history had a significant decrease in GFR value during follow-up. Patients who did not have fibrotic changes in first biopsy had same level of deterioration of GFR when compared with patients who had fibrotic changes in first biopsy.

CONCLUSION

We could not demonstrate a significant relation between complement deposition and renal fibrosis, and between complement deposition and GFR values. Our data demonstrated that graft outcomes and graft loss after acute rejection episodes cannot be predicted only with complement deposition on graft or only with graft fibrosis.

Complement C4 associations with altered microbial biomarkers exemplify gene-by-environment interactions in schizophrenia

Schizophrenia is a complex brain disorder with genetic and environmental factors contributing to its etiology. Complement C4 genes are schizophrenia susceptibility loci and are activated in response to infections and gut microbiome imbalances. We hypothesize that C4 genetic susceptibility predisposes individuals to neuropathological effects from pathogen exposures or a microbiome in dysbiosis. In 214 individuals with schizophrenia and 123 non-psychiatric controls, we examined C4 gene copy number and haplotype groups for associations with schizophrenia and microbial plasma biomarkers. C4A copy number and haplotypes containing HERV-K insertions (C4A-long; C4AL-C4AL) conferred elevated odds ratios for schizophrenia diagnoses (OR 1.58-2.56, p < 0.0001), while C4B-short (C4BS) haplogroups conferred decreased odds (OR 0.43, p < 0.0001). Haplogroup-microbe combinations showed extensive associations with schizophrenia including C4AL with Candida albicans IgG (OR 2.16, p < 0.0005), C4AL-C4BL with cytomegalovirus (CMV) IgG (OR 1.79, p < 0.008), C4BS with lipopolysaccharide-binding protein (LBP) (OR 1.18, p < 0.0001), and C4AL-C4AL with Toxoplasma gondii IgG (OR = 17.67, p < 0.0001). In controls, only one haplogroup-microbe combination was significant: C4BS with CMV IgG (OR 0.52, p < 0.02). In schizophrenia only, LBP and CMV IgG levels were inversely correlated with C4A and C4S copy numbers, respectively (R2 = 0.13-0.16, p < 0.0001). C4 haplogroups were associated with altered scores of cognitive functioning in both cases and controls and with psychiatric symptom scores in schizophrenia. Our findings link complement C4 genes with a susceptibility to infections and a dysbiotic microbiome in schizophrenia. These results support immune system mechanisms by which gene-environmental interactions may be operative in schizophrenia.

Imbalance of circulating CTLA4+ follicular helper and follicular regulatory T cells in obstetric antiphospholipid syndrome

Obstetric antiphospholipid syndrome (OAPS) is a systemic autoimmune disease that is characterized clinically by a variety of obstetric manifestations (fetal death and recurrent abortions) and serologically by the presence of antiphospholipid antibodies (aPLs). Whether dysregulation of Follicular helper T (Tfh) and Follicular regulatory T (Tfr) cells contribute to the immunopathogenesis in OAPS is still unknown. We analyzed phenotypic characterizations of circulating Tfh cells and Tfr cells in OAPS patients and healthy individuals. CTLA4(Cytotoxic T lymphocyte antigen 4)⁺ Tfh cells and CTLA4⁺ Tfr cells were declined and CTLA4⁺ Tfr/Tfh ratio and IL-21 were increased in OAPS patients compared with healthy controls. Percentages of CTLA4⁺ Tfh cells and CTLA4⁺ Tfr cells were the lowest in OAPS patients whose antiphospholipid antibodies (aPL) were triple positive. Increased CTLA4⁺ Tfr/Tfh ratio was positively correlated with anti-β2 glycoprotein I (anti-β2GPI) IgM, Complement 4(C4) or IL-21 in OAPS. Increased Th17 subtype and decreased Th1, Th2 subtypes in Tfh cells and Tfr cells, increased effector memory subtype and decreased central memory subtype of Tfh cells and Tfr cells were also observed in OAPS compared with healthy individuals. Our data demonstrated that an imbalance of circulating CTLA4⁺ Tfh cells, and Tfr cells correlates with the immunopathogenesis of OAPS.

Impact of Autoantibodies to Complement Components on the Disease Activity in SLE

INTRODUCTION

Systemic Lupus Erythematosus (SLE) is a chronic multi-system autoimmune disease with varied clinical presentations. Complement components are the major players in disease pathogenesis. This retrospective cross-sectional study was aimed at assessing the role of autoantibodies to these complement components and their association disease activity in newly diagnosed SLE patients from India.

METHOD

Clinically diagnosed SLE patients (n=57) classified as per 2015 ACR/SLICC revised criteria were enrolled between November 2016 to April 2017. Patients' sera were tested for C3 and C4 by nephelometry, while serum levels of factor H, factor P (properdin) as well as autoantibodies to C3, C4, factor H and factor P were detected by ELISA. GraphPad Prism Version 6.01 was used for statistical analysis. Mean, SD, SEM were calculated. Mann Whittney U-test, ANOVA, Chi-square test, Odd's Ratio were calculated. Pearson's correlation was used to study relativeness of the study parameters.

RESULTS

Among the 57 SLE patients, low C3 were seen in 51% patients, low C4 in 49%, low factor H in 19% and low factor P in 49% patients. Positivity for autoantibodies against complement components, anti-C3 were seen in 42% patients, anti-C4 in 7%, anti-factor H in 19% and anti-factor P in 28% patients. Serum levels of C3 (p=0.0009), C4 (p=0.0031) and anti-C3 autoantibodies (p=0.0029) were significantly associated with ACR/SLICC 2015 scores.

CONCLUSION

Hypocomplementemia was found to be associated with higher disease damage score in newly diagnosed SLE patients. This study adds novel arguments for the importance of the anti-C3 autoantibodies as a marker of SLE.

[Expression and diagnostic value of plasma miR-145 and miR-183 in children with lupus nephritis]

OBJECTIVE

To study the expression and diagnostic value of plasma miR-145 and miR-183 in children with lupus nephritis (LN).

METHODS

A total of 92 children with LN who were admitted from January 2016 to May 2019 were enrolled as the LN group, among whom 17 had type II LN, 15 had type III LN, 36 had type IV LN, 18 had type V LN, and 6 had type VI LN. Forty healthy children who underwent physical examination were enrolled as the healthy control group. According to Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), the 92 children with LN were further divided into a stable LN group with 34 children (SLEDAI score <10) and an active LN group with 58 children (SLEDAI score ≥10). RT-PCR was used to measure the expression of miR-145 and miR-183 in plasma. The receiver operating characteristic (ROC) curve was used to analyze the value of plasma miR-145, miR-183, and anti-dsDNA antibody in the diagnosis of LN. Pearson correlation analysis was used to investigate the correlation of the expression levels of miR-145 and miR-183 in plasma with laboratory markers.

RESULTS

The LN, active LN, and stable LN groups had significantly higher levels of anti-dsDNA antibody, C-reactive protein, serum creatinine (Scr), and blood urea nitrogen (BUN) than the control group (P<0.05). The active LN group had significantly higher SLEDAI score, anti-dsDNA antibody, Scr, and BUN than the stable LN group (P<0.05). The LN, active LN, and stable LN groups had significantly lower levels of complement C3, complement C4, and serum albumin (Alb) than the control group (P<0.05). The active LN group had a significantly lower level of Alb than the stable LN group (P<0.05). The LN, active LN, and stable LN groups had significantly lower plasma levels of miR-145 and miR-183 than the control group (P<0.01). The active LN group had significantly lower plasma levels of miR-145 and miR-183 than the stable LN group (P<0.01). The children with difference types of LN had significantly lower plasma levels of miR-145 and miR-183 than the control group (P<0.01), and the type V-VI group and the type IV group had significantly lower plasma levels of miR-145 and miR-183 than the type II-III group (P<0.01). The ROC curve analysis showed that the optimal cut-off values of plasma miR-145, miR-183, and anti-dsDNA antibody were 1.05, 0.62, and 186.30 IU/mL respectively, in the diagnosis of LN, and the combination of these three indices had the largest area under the ROC curve of 0.896 (95%CI: 0.835-0.955), with a sensitivity of 90.5% and a specificity of 84.2%. In the children with LN, the plasma levels of miR-145 and miR-183 were negatively correlated with SLEDAI score, anti-dsDNA antibody, Scr, and BUN (P<0.05) and were positively correlated with complement C3, complement C4, and Alb (P<0.05).

CONCLUSIONS

There are significant reductions in the expression levels of miR-145 and miR-183 in plasma in children with LN, which are correlated with the activity level and pathological typing of LN. Combined measurement of miR-145, miR-183, and anti-dsDNA antibody has a high value in the diagnosis of LN.

In vivo monitoring of rashes caused by systemic lupus erythematosus disease using snapshot spectral imaging

Monitoring the activity of systemic lupus erythematosus (SLE) is important to patient management. Blood biochemical indexes are commonly assessed but are both time demanding and traumatizing. In this study, a noninvasive and real-time spatial-spectral data tool was used to monitor SLE patients through rash spectral data. To build the relationship between the rash spectrum changes and changes in the patients' status, a snapshot hyperspectral Fourier transform imaging spectrometer was built to monitor the rash reflectance changes of hospitalized SLE patients. A simple rash activity index (RAI) which was normally distributed with the doctor's visual rating of rash severity was calculated from hyperspectral images. The sensitivity of the change in RAI is higher than complement 3/4 levels. RAI and anti-dsDNA antibodies both decreased as the patients recovered. Anti-dsDNA and complement 3/4 were important indicators of SLE activity suggesting that the RAI directly correlated with patient status. The snapshot spectrometer therefore provides an auxiliary method to monitor SLE disease.

[Levels of lymphocyte subsets, immunoglobulins, and complement C3 and C4 in children with hand-foot-mouth disease]

OBJECTIVE

To study the clinical value of lymphocyte subsets, immunoglobulins, and complement C3 and C4 in the evaluation of immune status in children with hand-foot-mouth disease (HFMD).

METHODS

A total of 282 children with HFMD were enrolled as the HFMD group, and 130 healthy children were enrolled as the healthy control group. The percentages of peripheral CD3⁺, CD4⁺, and CD8⁺ T lymphocytes, CD19⁺ B lymphocytes, and CD56⁺ natural killer cells were measured. The CD4⁺/CD8⁺ ratio was calculated. The levels of immunoglobulin A (IgA), immunoglobulin M (IgM), immunoglobulin G (IgG), and complement C3 and C4 were measured.

RESULTS

The multivariate analysis showed that compared with the healthy control group, the HFMD group had significantly lower percentages of CD3⁺, CD4⁺, and CD8⁺ T lymphocytes and levels of complement C3 and C4 (P<0.05), as well as significantly higher percentage of CD56⁺ natural killer cells and level of IgG (P<0.05). The individual effect analysis showed that the children aged 0-3 years in the HFMD group had a significantly higher CD4⁺/CD8⁺ ratio than the healthy control group (P<0.05); boys aged 0-3 and ≥3 years in the HFMD group had a significantly higher level of IgM than the healthy control group (P<0.05); boys aged ≥3 years and girls aged 0-3 years in the HFMD group had a significantly lower level of IgA than the healthy control group (P<0.05).

CONCLUSIONS

Cellular and humoral immunity disorders are observed in children with HFMD. The monitoring of lymphocyte subsets and immunoglobulin levels can provide a laboratory basis for immune status assessment in children with HFMD.

An update on the Chido/Rodgers blood group system

This update of the Chido/Rodgers blood group system (Mougey R. A review of the Chido/Rodgers blood group. Immunohematology 2010;26:30-8) summarizes the current understanding of the genetics and serology of this blood group (of which little has changed since the publication of the first review) in a table format as well as summarizes the gene frequencies and disease association with low copy number of C4A or C4B genes. The International Society of Blood Transfusion (ISBT) has designated the ISBT number 017 to this system and the abbreviation CH/RG for the antigen or antibody notation. There are currently nine antigens in the CH/RG system. A brief discussion on the serologic challenges of detecting the antibodies and of newer information on the disease associations is provided. This review concludes with some speculation on how our understanding of C4 genes may be illuminated by current investigation into complexities of autoimmunity and the role of C4 and its progression to a disease state.

Investigation of peripheral complement factors across stages of psychosis

The complement cascade has been proposed to contribute to the pathogenesis of schizophrenia. However, it remains unclear whether peripheral complement levels differ in cases compared to controls, change over the course of illness and whether they are associated with current symptomatology. This study aimed to: i) investigate whether peripheral complement protein levels are altered at different stages of illness, and ii) identify patterns among complement protein levels that predict clinical symptoms. Complement factors C1q, C3 and C4 were quantified in 183 participants [n = 83 Healthy Controls (HC), n = 10 Ultra-High Risk (UHR) for psychosis, n = 40 First Episode Psychosis (FEP), n = 50 Chronic schizophrenia] using Multiplex ELISA. Permutation-based t-tests were used to assess between-group differences in complement protein levels at each of the three illness stages, relative to age- and gender-matched healthy controls. Canonical correlation analysis was used to identify patterns of complement protein levels that correlated with clinical symptoms. C4 was significantly increased in chronic schizophrenia patients, while C3 and C4 were significantly increased in UHR patients. There were no differences in C1q, C3 and C4 in FEP patients when adjusting for BMI. A molecular pattern of increased C4 and decreased C3 was associated with positive and negative symptom severity in the pooled patient sample. Our findings indicate that peripheral complement concentration is increased across specific stages of psychosis and its imbalance may be associated with symptom severity. Given the small sample size of the UHR group, these findings should be regarded as exploratory, requiring replication.

Deposition of mannose-binding lectin and ficolins and activation of the lectin pathway of complement on the surface of polyurethane tubing used for cardiopulmonary bypass

The artificial surface used for cardiopulmonary bypass (CPB) is a crucial factor activating the complement system and thus contributing to the generation of a systemic inflammatory response. The activation of classical and alternative pathways on this artificial surface is well known. In contrast, lectin pathway (LP) activation has not been fully investigated, although noted during CPB in several studies. Moreover, we have recently proved the contribution of the LP to the generation of the systemic inflammatory response syndrome after pediatric cardiac surgery. The aim of this study was to assess LP-mediated complement activation on the surface of polyurethane CPB circuit tubing (noncoated Chalice ® ), used for CPB procedures in children with congenital heart disease. We found deposition of mannose-binding lectin, ficolin-1, -2, and -3 on the surface of unused tubing and on tubing used for CPB from a small minority of patients. Furthermore, we observed deposition of complement C4 activation products on tubing used for CPB and previously unused tubing after incubation with normal serum. The latter finding indicates LP activation in vitro on the polyurethane surface. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1202-1208, 2018.

[Correlation of occupational stress with serum levels of immunoglobulins and complement in police]

OBJECTIVE

To investigate the correlation of occupational stress with the serum levels of immunoglobulins(IgG, IgM, and IgA) and complement(C3 and C4).

METHODS

In May 2011, convenience sampling and cluster sampling were used to select 225 policemen from a local police station as study subjects. A questionnaire was used to investigate demographic features and occupational stress, and the immunoturbidimetric assay was applied to measure the serum levels of IgG, IgM, IgA, and complement C3 and C4.

RESULTS

Positive affectivity was positively correlated with the concentration of IgG(r=0.084, P<0.01); positive affectivity, coping strategy, and sleep quality were positively correlated with the concentration of IgM(r= 0.146, 0.155, and 0.203, all P<0.05); negative affectivity was negatively correlated with the concentration of IgM(r=-0.185, P<0.05). Reward and sleep quality were positively correlated with the concentration of C3(r= 0.172 and 0.285, both P<0.05), and negative affectivity was negatively correlated with the concentration of C3 (r=-0.174, P<0.05); sleep quality was positively correlated with the concentration of C4(r= 0.173, P<0.05), and negative affectivity was negatively correlated with the concentration of C4(r=-0.164, P<0.05). The logistic regression analysis revealed that the risks for a reduced concentration of IgG in the groups with high scores of social support and positive affectivity were 0.460 and 0.495 times those in the groups with low scores, while the risk for a reduced concentration of IgM in the group with a high score of coping strategy was 0.482 times that in the group with a low score.

CONCLUSION

Occupational stress is correlated with the serum levels of immunoglobulins and complement.

Placental C4d deposition is a feature of defective placentation: observations in cases of preeclampsia and miscarriage

Placental C4d deposition is frequent in preeclampsia, and shallow placentation is a characteristic of both preeclampsia and miscarriage. This study was conducted to determine the relationship among placental C4d, maternal human leukocyte antigen (HLA) antibodies, and placental pathology in preeclampsia and miscarriage cases. The patient population (N = 104) included those with (1) preterm preeclampsia with fetal growth restriction (PE-FGR; n = 21), (2) preterm preeclampsia (PE; n = 20), (3) spontaneous preterm delivery (sPTD; n = 39), and (4) miscarriage (n = 24). C4d immunohistochemistry was performed, and the presence of maternal plasma HLA antibodies was examined. C4d staining of the syncytiotrophoblast was more frequent in PE-FGR patients (76.2 %) than in PE (10.0 %; p < 0.001) and sPTD (2.6 %; p < 0.001) patients. Maternal HLA antibody-positive rate was not different among the study groups. There was a significant correlation between C4d immunoreactivity and placental pathology consistent with maternal vascular underperfusion (p < 0.001) but not with maternal HLA antibody status. In miscarriages, the positive rates of C4d, HLA class I, and HLA class II antibodies were 58.3, 25.0, and 12.5 %, respectively. There was no correlation between the presence of maternal HLA class I or II antibodies and placental C4d immunoreactivity. This study confirms frequent placental C4d deposition in preeclampsia with fetal growth restriction and miscarriage. The association between placental C4d deposition and pathological findings of maternal vascular underperfusion suggests that C4d staining of the syncytiotrophoblast is a consequence of defective placentation rather than of a specific maternal immune response against fetal HLA. The study also demonstrates the usefulness of C4d as a biomarker of placentas at risk.

Clinical and laboratory characteristics that differentiate hereditary angioedema in 72 patients with angioedema

BACKGROUND

Hereditary angioedema (HAE) is a rare but life-threatening condition that results from mutations in C1-inhibitor (C1-INH). Since distinguishing HAE from other causes of angioedema (AE) is a critical problem in emergencies, the objective of the present study was to clarify the differences between HAE and other forms of AE.

METHODS

Seventy-two patients with AE were enrolled in this study. The medical history and laboratory data of patients with HAE at the first visit were compared to those with other types of AE.

RESULTS

Subjects included 23 patients with HAE, 33 with mast cell-mediated AE, 5 with drug-induced AE and 11 with idiopathic AE. The average age of HAE onset (19.5 ± 8.0 years old) was significantly lower than in other groups. A family history of AE was noted in 82.6% of HAE patients, which was significantly higher than other groups. Swelling affecting the extremities and gastrointestinal (GI) tract was observed in the majority (60 to 80%) of HAE patients. Life threatening laryngeal edema was observed in 30.4% of HAE patients. In 95.6% of HAE patients serum levels of C4 were less than the lower limit of the normal range. In our subjects, the sensitivity and specificity of low C4 for HAE were 95.6% and 93.8%, respectively.

CONCLUSIONS

Early onset of AE, positive family history, recurrent AE in the extremities and GI tract, and suffocation are distinctive characteristics of HAE. A low serum level of C4 is a useful marker for making a differential diagnosis of HAE.

Diagnosis and management of hereditary angioedema

Hereditary angioedema (HAE) is characterized by sudden attacks of deep tissue swelling caused by C1 inhibitor deficiency. Swelling severity can vary from mild to severe, and some patients are at risk for disability and death from either asphyxiation or hypovolemic shock. Many HAE attacks are precipitated by trauma or stress. The extremities, genitalia, trunk, bowels, face, and larynx are commonly affected areas, but swelling can affect any single part of the body or multiple sites. Symptoms typically worsen over 24 to 36 hours and resolve within 48 hours. Because many symptoms of HAE overlap with those of other medical conditions, diagnosis may be delayed. A thorough family history can identify the signature symptoms of HAE, which include a family history of HAE, recurrent edema without urticaria, and symptomatic worsening during puberty. The author presents two hypothetical cases of HAE and reviews the clinical hallmarks of this condition, diagnostic tests, and available treatments.

Immunosuppression in patients with severe acute pancreatitis

BACKGROUND

In severe acute pancreatitis (SAP), immunologic impairment in the early phase may be linked to subsequent infectious complications. In this study, immunologic alterations in patients with SAP were analyzed, and immunologic parameters related to infectious complications were clarified.

METHODS

A total of 101 patients with SAP were analyzed retrospectively. Various immunologic parameters on admission were analyzed and compared between the infection group and noninfection group during SAP. Furthermore, chronologic change in the lymphocyte count was investigated, and its utility for predicting infection was compared with conventional scoring systems.

RESULTS

Serum immunoglobulin G (IgG), serum IgM, lymphokine-activated killer cell activity, and natural killer cell activity were low, and the incidence of abnormally low values was 50.0%, 65.0%, 45.5%, and 42.4%, respectively. Serum complement factor 3 was significantly negatively correlated with the APACHE II score. The lymphocyte count was decreased below the normal range, and was significantly negatively correlated with the APACHE II score. CD4-, CD8-, and CD20-positive lymphocyte counts were below the normal range, and CD4- and CD8-positive lymphocyte counts were significantly lower in the infection group. The lymphocyte count on day 14 after admission was significantly lower in the infection group and was more useful for predicting infection than conventional scoring systems.

CONCLUSIONS

Immunosuppression occurs from the early phase in SAP, and quantitative impairment of lymphocytes, mainly T lymphocytes, may be closely related to infectious complications during SAP. CD4- and CD8-positive lymphocyte counts on admission and the lymphocyte count on day 14 after admission may be useful for predicting infection.

Leishmania (Viannia) braziliensis: interaction of mannose-binding lectin with surface glycoconjugates and complement activation. An antibody-independent defence mechanism

The activation of complement on the surface of Leishmania promastigotes appears to be an important factor for parasite infectivity in the mammalian host, allowing their attachment and the invasion of macrophages via complement receptors. Mannose-binding lectin (MBL) is a well-known complement activator and an efficient opsonine. We have investigated here whether serum and purified MBL bind to and promote lysis of live promastigotes of L. braziliensis; and evaluated the deposition of MBL, C1q, C4 and C3 on the parasite surface after interaction with non-immune normal human serum (NHS). We observed that both serum MBL and the purified MBL-MASP complex bind to the surface of L. braziliensis and that this binding occurred via the carbohydrate recognition domains of MBL. The binding of MBL, however, did not affect the lytic effect of complement on the parasites. The deposition of C1q, C4, C3 and parasite lysis was observed after incubation with NHS. EDTA but not EGTA abolished C3 deposition on the parasite surface, indicating the involvement of the alternative pathway in this process. Our results indicate that MBL binds to L. braziliensis and that this is mediated by a specific carbohydrate on the surface of parasites and provides evidence for antibody-independent mechanisms that complement activation on the parasite surface.

Androgen receptor and molecular mechanisms of male-specific gene expression

Androgen's central role in male differentiation, fertility and aggression is evident from human pathologies and animal behaviour studies. Androgens directly regulate gene expression via the androgen receptor (AR), a member of the nuclear receptor superfamily. Nuclear receptors share a modular structure, with specialized domains for DNA binding, ligand binding, and transcriptional activation. Ligand-induced conformational changes in receptor trigger coregulators to modify chromatin structure. This in turn controls access of the transcriptional machinery to targeted genes. Given a common receptor structure and mode of action, AR must rely on several mechanisms for transcriptional specificity. As we have shown for the mouse sex-limited protein gene, these include use of divergent DNA binding sites, cooperativity between sites enhanced by intra- and intermolecular interaction of AR's N- and C-termini, and coactivator interactions. Although individual mechanisms lack sufficient specificity or strength, the summed interplay of response elements and accessory factor binding achieves precise gene activation. In addition to direct gene activation, AR elicits male-specific expression by modulating other hormonal pathways. For example, androgen control of growth hormone secretion induces male-specific genes in the liver. This sex-specific expression is further enforced by a novel class of KRAB zinc finger repressors. Their variation between species evidences diverging mechanisms of sexual differentiation, echoing AR's own recent origin.

Drawing lines in the sand: even skipped et al. and parasegment boundaries

The pair-rule segmentation gene even skipped (eve) is required to activate engrailed stripes and to organize odd-numbered parasegments (PSs). The protein product Eve has been shown to be an active repressor of transcription, and recent models for Eve function suggest that activation of engrailed is indirect, but these models have not been fully tested. Here we identify the forkhead domain transcription factor Sloppy-paired as the key intermediate in the initial activation of engrailed by Eve in odd-numbered parasegments. We also analyze the roles of the transcription factors Runt and Odd-skipped in this process. Detailed analysis of engrailed and pair-rule gene expression in various mutant combinations shows how eve activates engrailed by repressing these engrailed repressors, and further indicates that mutual repression among pair-rule genes plays an important role in establishing parasegment boundaries. We present a new model of pair-rule gene function that explains the response of these boundaries to the relative levels of Eve and Fushi Tarazu.

The topology of the regulatory interactions predicts the expression pattern of the segment polarity genes in Drosophila melanogaster

Expression of the Drosophila segment polarity genes is initiated by a pre-pattern of pair-rule gene products and maintained by a network of regulatory interactions throughout several stages of embryonic development. Analysis of a model of gene interactions based on differential equations showed that wild-type expression patterns of these genes can be obtained for a wide range of kinetic parameters, which suggests that the steady states are determined by the topology of the network and the type of regulatory interactions between components, not the detailed form of the rate laws. To investigate this, we propose and analyse a Boolean model of this network which is based on a binary ON/OFF representation of mRNA and protein levels, and in which the interactions are formulated as logical functions. In this model the spatial and temporal patterns of gene expression are determined by the topology of the network and whether components are present or absent, rather than the absolute levels of the mRNAs and proteins and the functional details of their interactions. The model is able to reproduce the wild-type gene expression patterns, as well as the ectopic expression patterns observed in overexpression experiments and various mutants. Furthermore, we compute explicitly all steady states of the network and identify the basin of attraction of each steady state. The model gives important insights into the functioning of the segment polarity gene network, such as the crucial role of the wingless and sloppy paired genes, and the network's ability to correct errors in the pre-pattern.

The regulator of sex-limitation gene, rsl, enforces male-specific liver gene expression by negative regulation

Expression of a broad array of proteins is sexually dimorphic in rodent liver, dependent on sex-specific patterns of GH secretion. Mice carrying rsl (regulator of sex limitation) alleles, discovered as trans-acting loci affecting the mouse sex-limited protein (Slp) gene, reveal an additional axis in male-specific gene regulation. Slp expresses in adult males, but in rsl homozygous mice, Slp is also expressed in females. In this study, we examined congenic rsl strains to determine rsl's site of action, breadth of targets, and interaction with hormonal induction. We show that rsl affects Slp in liver, but not kidney, and that Rsl acts on a spectrum of male-specific liver genes, including mouse urinary proteins and a cytochrome P450 expressed predominantly by males, Cyp 2d-9, but does not act on the female-prominent P450, Cyp 2a-4. Slp expression in hypophysectomized or Tfm/Y rsl mice reveals that Rsl action is independent of GH or androgen signaling. Further, parabiosis of Rsl and rsl mice does not alter expression patterns, consistent with rsl action being liver intrinsic. Finally, Slp expression initiates earlier in rsl mice, suggesting that Rsl operates before, as well as independently of, hormonal induction. This characterization suggests Rsl functions to repress transcription of a set of genes that have in common their hormonal induction in male liver, and thus accentuates sexual dimorphism of liver gene expression.

Activation of the complement system by different autologous transfusion devices: an in vitro study

BACKGROUND

The aim of the present investigation was to study whether autologous transfusion devices activate the complement system and whether complement-activated blood is more vulnerable to further activation during processing.

STUDY DESIGN AND METHODS

Forty-eight blood units were randomized to be processed by one of three different salvage systems: Group 1 underwent whole blood filtration (hemofiltration) (n=16); Group 2 underwent continuous processing, saline washing, and centrifugation (CATS, Fresenius AG ) (n=16); and Group 3 underwent saline washing and centrifugation (Cell-Saver, Haemonetics Corp.) (n=16). Eight blood units for each system were activated with cobra venom factor (CVF) at a concentration of 0.2 U per mL whole blood before processing. C activation was studied by determinations of C4d, Bb, C3a, and SC5b-9. Samples were drawn from whole blood, processed blood, and the waste bags.

RESULTS

The concentrations of Bb, C3a, and SC5b-9 in whole blood after activation with CVF were significantly elevated compared to blood that was not activated (p < 0.01). Processed blood from hemofiltration contained significantly higher levels of complement-split products than techniques that use washing and centrifugation. The concentrations of SC5b-9 in blood processed by hemofiltration were higher in the experiments with CVF activation (p < 0.05).

CONCLUSION

The tested autologous transfusion systems did not themselves activate the complement system, and complement-activated blood was not more vulnerable to further activation during processing. A blood-salvaging technique that used washing and centrifugation reduced elevated concentrations of complement-split products, whereas hemofiltration did not.

A case of severe C4d-positive kidney allograft dysfunction in the absence of histomorphologic features of rejection

Acute antibody-mediated (humoral) renal allograft rejection has emerged as a clinicopathological entity that carries a poor prognosis. Its diagnosis is based on typical pathohistologic features, serologic detection of donor-specific alloantibodies and the immunohistochemical finding of endothelial deposits of the complement split product C4d. We herein report a case of severe antibody-mediated graft injury after spousal-donor kidney transplantation. Despite an increased risk for humoral presensitization in the female recipient (three previous pregnancies), donor-specific alloantibodies were not detectable before transplantation. After initial graft function, severe graft dysfunction occurred one week after transplantation. A renal biopsy revealed no histomorphologic features of rejection. However, immunohistochemical detection of diffuse C4d deposits along peritubular capillaries suggested acute humoral rejection. The diagnosis of antibody-mediated rejection was confirmed by the detection of de-novo production of anti-donor alloantibodies. Graft dysfunction was resistant to high dose steroids or antilymphocyte antibody therapy. However, a recovery of graft function could be achieved by antibody elimination using immunoadsorption therapy. This case reinforces the high diagnostic value of C4d staining. In severe graft dysfunction humoral immune mechanisms should be considered, even when histopathologic features of humoral rejection are completely absent.

Continuous 48-h C1-inhibitor treatment, following reperfusion therapy, in patients with acute myocardial infarction

AIMS

Complement inhibition by C1-inhibitor has been shown to reduce myocardial ischaemia-reperfusion injury in animal models. We therefore studied the effects of intravenous C1-inhibitor, following reperfusion therapy, in patients with acute myocardial infarction.

METHODS AND RESULTS

C1-inhibitor therapy was started not earlier than 6h after acute myocardial infarction, in order to prevent interference with thrombolytic therapy. A loading dose of C1-inhibitor was followed by a continuous infusion for 48 h, using three escalating dosage schemes. Efficacy of complement inhibition was estimated from C4 activation fragments. Plasma concentrations of myocardial proteins were compared to values measured in matched control patients. In 22 patients, C1-inhibitor was well tolerated and drug-related adverse events were not observed. Target plasma levels of C1-inhibitor were reached, with values of 48.2 ml.kg(-1) for distribution space and 35.5h for the half-life time of C1-inhibitor. A dose-dependent reduction of C4 fragments was found P=0.005). In 13 patients who received early thrombolytic therapy, release of troponin T and creatine kinase-MB(mass) was reduced by 36% and 57%P =0.001), compared to 18 controls.

CONCLUSION

Continuous 48-h treatment with C1-inhibitor provides safe and effective inhibition of complement activation after reperfused acute myocardial infarction and may reduce myocardial injury.

Serum concentration of Hakata antigen, a member of the ficolins, is linked with inhibition of Aerococcus viridans growth

BACKGROUND

Hakata antigen (Hakata) is a novel serum glycoprotein that consists of collagen- and fibrinogen-like domains, similar to ficolin/p35. Our research suggested that serum Hakata may be a target of a polysaccharide (PSA) produced by Aerococcus viridans.

METHODS

A. viridans was incubated with human plasma and Hakata-depleted plasma to examine Hakata binding and growth inhibition of A. viridans through binding with PSA.

RESULTS

When A. viridans was mixed with human acid citrate dextrose-one (ACD-A) plasma, it pulled down Hakata complexed with mannose-binding lectin (MBL)-associated serine proteases 1 and 2 (MASP-1 and MASP-2). This complex had the potential for C4 deposition. Serum Hakata circulates as Hakata-MASPs complex in the blood and is proteolytically active. By mixing A. viridans with human plasma, we prepared a Hakata-depleted plasma, deficient in Hakata-MASPs complex. This plasma failed to inhibit A. viridans growth plasma, but does not inhibit Staphylococcus aureus, Yersinia enterocolitica and Escherichia coli. However, a decrease of growth inhibition of A. viridans in Hakata-depleted plasma could be restored by adding a Hakata-MASPs complex preparation in a dose-dependent manner. On the other hand, the Hakata-MASPs complex exhibited strong binding to A. viridans, but not to S. aureus, Y. enterocolitica and E. coli.

CONCLUSIONS

The serum concentration of Hakata is linked with growth inhibition of A. viridans upon binding of Hakata via PSA.

Functional interplay between two response elements with distinct binding characteristics dictates androgen specificity of the mouse sex-limited protein enhancer

Many of the aspects involved in steroid-specific transcriptional regulation are still unsolved to date. We describe here the detailed characterization of the mouse sex-limited protein enhancer as a paradigm for androgen-specific control of gene expression. By deletion analysis, we delineate the minimal enhancer region displaying androgen sensitivity and specificity. We also show that each of the three hormone response elements (HRE), which constitute this minimal enhancer region, is essential but not sufficient for its functionality. When investigated as isolated elements, HRE1 is inactive and HRE3 is a potent androgen response element as well as GRE. Only the non-canonical HRE2 (5-TGGTCAgccAGTTCT-3') is capable of conferring an androgen-specific transcriptional response to a heterologous promoter. This finding is correlated with the fact that HRE2 is recognized in binding assays in vitro by the DNA-binding domain (DBD) of the androgen but not the glucocorticoid receptor, while HRE3 is recognized by both DBDs. Differential binding of the androgen receptor to HRE2 in the context of the enhancer was analyzed in more detail in footprinting assays in vitro. In transient transfection experiments using chimeric receptors, the inability of the glucocorticoid receptor to transactivate via the slp-ARU as well as the isolated slp-HRE2 was rescued by the replacement of its DNA-binding domain with that of the androgen receptor. Our data suggest that the functional interplay between the weak, but highly androgen-specific HRE2 and the adjacent strong, but non-selective HRE3 is the major determinant in the generation of androgen specificity of transcriptional response via the sex-limited protein enhancer.

Androgen receptor interactions with Oct-1 and Brn-1 are physically and functionally distinct

POU domain proteins interact positively or negatively with steroid hormone receptors, depending on the precise array of these and other factors assembled on target gene promoters. Octamer transcription factor 1 (Oct-1), a ubiquitous POU factor, is implicated in androgen induction of the mouse sex-limited protein (Slp) gene based on protein-DNA interaction studies. However, direct evidence for a role of Oct-1 in the hormone response has been difficult to obtain. Brain 1 (Brn-1), another POU factor, is more tissue-specific, expressing in brain and also in kidney, which is a major site of Slp synthesis. We compared the interaction of the androgen receptor (AR) with Oct-1 and Brn-1 to reveal the more likely candidate for regulation of Slp. In transfection, addition of either Oct-1 or Brn-1 reduced AR activation, regardless of the presence of an octamer-like sequence in the enhancer, suggesting interference was indirect. However, when the octamer-like element was changed to a consensus octamer site, Brn-1, but not Oct-1, strongly enhanced androgen activation. This correlated with Brn-l's preference for the consensus octamer sequence in DNA binding assays. Direct interaction of AR with glutathione-S-transferase-(GST)-fused Oct-1 was DNA-dependent, while Brn-l-AR association was not. Chimeric Brn-1 and Oct-1 POU domains demonstrated that the DNA-dependent AR interaction relied on the origin of the POU homeodomain. However, in the context of full-length Brn-1 and Oct-1 chimeric proteins, the POU homedomain was not sufficient to confer the distinct behaviors of these factors in vivo, but instead revealed the importance of an N-terminal transactivation domain in Brn-1. These results demonstrate that functional interaction of Oct-1 and Brn-1 with AR is determined by the precise sequence of the octamer binding site, and by differential interaction of the POU factors with AR and other components of the transcriptional machinery.