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Alzheimer's disease (AD) is characterized by abnormal inflammatory responses, and complement C5a (C5a) is known to initiate inflammation. This study aimed to investigate the associations between serum C5a, inflammatory responses, and cognitive function in AD patients. A total of 242 AD patients and 132 age-matched controls were included. Enzyme-linked immunosorbent assay revealed increased levels of C5a, interleukin (IL)-4, IL-6, IL-10, IL-1β, and tumor necrosis factor (TNF)-α with advancing stages of AD. Pearson correlation coefficient and receiver operating characteristic curve revealed positive correlations between serum C5a levels, inflammatory cytokine levels, Neuropsychiatric Inventory (NPI) and Activities of Daily Living (ADL) scores, and negative correlations with Mini-mental State Examination (MMSE) and Montreal cognitive assessment (MoCA) scores. Serum C5a above 68.68 pg/mL could aid in the diagnosis of AD. Multivariable logistic analysis revealed that serum C5a was an independent risk factor for IL-1β/IL-6/IL-10/TNF-α and an independent protective factor for IL-4. Higher serum C5a levels were associated with lower MMSE and MoCA scores. In conclusion, elevated serum C5a levels were beneficial for AD diagnosis and predictive of inflammation and cognitive dysfunction., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: Invasive candidiasis poses a life-threatening risk, and early prognosis assessment is vital for timely interventions to reduce mortality. Serum C5a levels have recently been linked to prognosis, but confirmation in cancer patients is pending., Methods: We detected the concentrations of serum C5a in hospitalized cancer patients with invasive candidiasis from 2020 to 2023, and retrospectively analyzed the clinical data., Results: 372 cases were included in this study, with a 90-day mortality rate of 21.8%. Candida albicans (48.7%) remained the predominant pathogen, followed by Candida glabrata (25.5%), Candida tropicalis (12.4%), and Candida parapsilosis (8.3%). Gastrointestinal cancer was the most diagnosed pathology type (37.6%). Serum C5a demonstrated a noteworthy correlation with 90-day mortality, and employing a cutoff value of 36.7 ng/ml revealed significantly higher 90-day mortality in low-C5a patients (41.2%) compared to high-C5a patients (6.3%) (p < 0.001). We also identified no source control, no surgery, metastasis, or chronic renal failure independently correlated with the 90-day mortality. Based on this, a prognostic model combining C5a and clinical parameters was constructed, which performed better than models built solely on C5a or clinical parameters. Furthermore, we weighted scores to each parameter in the model and presented diagnostic sensitivity and specificity corresponding to different score points calculated by the model., Conclusion: We constructed a prognostic scoring model including serum C5a and clinical parameters, which would contribute to precise prognosis assessment and benefit the outcome among cancer patients., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Alzheimer's disease (AD) is a common cause of dementia. Serum complement factor 5a (C5a) is exceedingly implicated in AD. We explored the role of C5a levels in AD patients of different severity., Methods: Mild, moderate, and severe AD patients, and healthy controls were included. C5a and pro-inflammatory factor (TNF-α, IL-1β, IL-6, CRP) levels were assessed by ELISA, and cognitive function was evaluated by Mini-Mental state examination (MMSE) score. The correlations between C5a, inflammatory factor levels, MMSE score, and plasma Aβ42/Aβ40 ratio were analyzed by Pearson tests. Independent risk factors for AD aggravation were assessed by logistic multivariate regression analysis. According to the cut-off value of receiver operating characteristic (ROC) curve analysis of C5a level, AD patients were assigned into low/high expression groups, and severe AD incidence was compared. Severe AD cumulative incidence was analyzed by Kaplan-Meier curve., Results: Serum C5a, TNF-α, IL-1β, IL-6 and CRP levels were raised, and MMSE score was lowered in AD. Serum C5a, TNF-α, IL-1β, IL-6 and CRP levels in severe AD patients were higher than those in mild/moderate AD patients, but there were no significant differences in these cytokines between moderate and mild AD groups. The MMSE score of severe AD patients was lower than that of mild/moderate AD patients. Serum C5a level was positively correlated with serum TNF-α, IL-1β, IL-6, and CRP levels, and negatively correlated with MMSE score, with no obvious correlation with plasma Aβ42/Aβ40 ratio. Serum C5a level was one of the independent risk factors for AD aggravation. The occurrence of severe AD might be related to an increase in serum C5a level., Conclusion: Serum C5a level increased with AD severity, and its expression was positively correlated with serum pro-inflammatory factor levels, and negatively correlated with cognitive function., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Cystic fibrosis (CF) disease is characterized by an intense airway inflammatory response mediated by neutrophils and chronic respiratory infections caused by P. aeruginosa . High levels of the complement component C5a, the strongest neutrophil chemoattractant molecule, are commonly found in the CF lung and have been associated with a worsening of the disease. In this study, we investigated how the isolates from CF patients modulate the levels of C5a and identified the bacterial factors involved. We demonstrated that most isolates from airway chronic infections induce the production and accumulation of C5a, an effect attributable to the loss of C5a cleavage by the exoproteases alkaline protease (AprA) and elastase B (LasB). Furthermore, we found that lack of the bacterial protease-dependent C5a degradation is due to mutations in the master regulator LasR. Thus, complementation of a non-C5a-cleaving CF isolate with a functional wild-type LasR restored its ability to express both proteases, cleave C5a and reduce neutrophil recruitment in vitro. These findings suggest that the non-cleaving C5a phenotype acquired by the LasR variants frequently isolated in CF patients may account for the strong neutrophilia and general neutrophil dysfunction predisposing toward increased inflammation and reduced bacterial clearance described in CF patients.

Numerous publications have underlined the link between complement C5a and the clinical course of COVID-19. We previously reported that levels of C5a remain high in the group of severely ill patients up to 90 days after hospital discharge. We have now evaluated which complement pathway fuels the elevated levels of C5a during hospitalization and follow-up. The alternative pathway (AP) activation marker C3bBbP and the soluble fraction of C4d, a footprint of the classical/lectin (CP/LP) pathway, were assessed by immunoenzymatic assay in a total of 188 serial samples from 49 patients infected with SARS-CoV-2. Unlike C5a, neither C3bBbP nor C4d readouts rose proportionally to the severity of the disease. Detailed correlation analyses in hospitalization and follow-up samples collected from patients of different disease severity showed significant positive correlations of AP and CP/LP markers with C5a in certain groups, except for the follow-up samples of the patients who suffered from highly severe COVID-19 and presented the highest C5a readouts. In conclusion, there is not a clear link between persistently high levels of C5a after hospital discharge and markers of upstream complement activation, suggesting the existence of a non-canonical source of C5a in patients with a severe course of COVID-19., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Kowalska, Kuźniewska, Senent, Tavira, Inogés, López-Díaz de Cerio, Pio, Okrój and Yuste.)

Coronavirus disease-2019 (COVID-19) was declared as a pandemic by WHO in March 2020. SARS-CoV-2 causes a wide range of illness from asymptomatic to life-threatening. There is an essential need to identify biomarkers to predict disease severity and mortality during the earlier stages of the disease, aiding treatment and allocation of resources to improve survival. The aim of this study was to identify at the time of SARS-COV-2 infection patients at high risk of developing severe disease associated with low survival using blood parameters, including inflammation and coagulation mediators, vital signs, and pre-existing comorbidities. This cohort included 89 multi-ethnic COVID-19 patients recruited between July 14 th and October 20 th 2020 in Doha, Qatar. According to clinical severity, patients were grouped into severe (n=33), mild (n=33) and asymptomatic (n=23). Common routine tests such as complete blood count (CBC), glucose, electrolytes, liver and kidney function parameters and markers of inflammation, thrombosis and endothelial dysfunction including complement component split product C5a, Interleukin-6, ferritin and C-reactive protein were measured at the time COVID-19 infection was confirmed. Correlation tests suggest that C5a is a predictive marker of disease severity and mortality, in addition to 40 biological and physiological parameters that were found statistically significant between survivors and non-survivors. Survival analysis showed that high C5a levels, hypoalbuminemia, lymphopenia, elevated procalcitonin, neutrophilic leukocytosis, acute anemia along with increased acute kidney and hepatocellular injury markers were associated with a higher risk of death in COVID-19 patients. Altogether, we created a prognostic classification model, the CAL model (C5a, Albumin, and Lymphocyte count) to predict severity with significant accuracy. Stratification of patients using the CAL model could help in the identification of patients likely to develop severe symptoms in advance so that treatments can be targeted accordingly., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Cyprian, Suleman, Abdelhafez, Doudin, Masud Danjuma, Mir, Parray, Yousaf, Siddiqui, Abdelmajid, Mulhim, Al-Shokri, Abukhattab, Shaheen, Elkord, Al-khal, Elzouki and Girardi.)

In this observational case-control study, circulating levels of complement factors C3a and C5a and leukotriene B4 (LTB4) were analysed in abdominal aortic aneurysm (AAA) patients regarding their association with diagnosis and prognosis. Serum C5a was significantly raised in AAA patients compared to healthy controls-median 84.5 ng/ml (IQR = 37.5 ng/ml) vs. 67.7 ng/ml (IQR = 26.2 ng/ml), p = 0.007-but was not elevated in patients with athero-occlusive disease. Serum C5a levels correlated significantly with the increase in maximum AAA diameter over the following 6 months (r = 0.319, p = 0.021). The median growth in the lowest quartile of C5a (< 70 ng/ml) was 50% less compared to the highest C5a quartile (> 101 ng/ml): 1.0 mm/6 months (IQR = 0.8 mm) vs. 2.0 mm/6 months (IQR = 1.5 mm), p = 0.014. A log-linear mixed model predicted AAA expansion based on current diameter and C5a level. To our knowledge, this is the first study linking complement activation, in particular C5a serum level, with AAA progression., (© 2020. The Author(s).)

Neutrophil infiltration to ischemic tissues following reperfusion worsens injury. A key driver of neutrophil recruitment and activation is the complement factor C5a, which signals through two receptors, C5aR1 and C5aR2. In this study, we used a neutrophil-dependent mouse model of intestinal ischemia-reperfusion (IR) injury to investigate the underexplored role of C5aR2 in neutrophil mobilization, recruitment, and disease outcomes. We show that intestinal IR induces rapid neutrophil mobilization along with a concomitant reduction in plasma C5a levels that is driven by both C5aR1 and C5aR2. Intestinal IR in C5aR2 -/- mice led to worsened intestinal damage and increased neutrophil infiltration. Inhibition of C5aR1 signaling in C5aR2 -/- mice with PMX53 prevented neutrophil accumulation and reduced IR pathology, suggesting a key requirement for enhanced neutrophil C5aR1 activation in the absence of C5aR2 signaling. Interestingly, C5aR2 deficiency also reduced circulating neutrophil numbers after IR, as well as following G-CSF-mediated bone marrow mobilization, which was independent of C5aR1, demonstrating that C5aR2 has unique and distinct functions from C5aR1 in neutrophil egress. Despite enhanced tissue injury in C5aR2 -/- IR mice, there were significant reductions in intestinal proinflammatory cytokines, highlighting complicated dual protective/pathogenic roles for C5aR2 in pathophysiology. Collectively, we show that C5aR2 is protective in intestinal IR by inhibiting C5aR1-mediated neutrophil recruitment to the ischemic tissue. This is despite the potentially local pathogenic effects of C5aR2 in increasing intestinal proinflammatory cytokines and enhancing circulating neutrophil numbers in response to mobilizing signals. Our data therefore suggest that this balance between the dual pro- and anti-inflammatory roles of C5aR2 ultimately dictates disease outcomes., (Copyright © 2020 by The American Association of Immunologists, Inc.)

Immune responses to nitrogen gas bubbles, particularly activation of inflammation via the complement cascade, have been linked to the development of symptoms and damage associated with decompression sickness (DCS) in humans. Marine mammals were long thought not to be susceptible to such dive-related injury, yet evidence of DCS-like injury and new models of tissue nitrogen super-saturation suggest that bubbles may routinely form. As such, it is possible that marine mammals have protective adaptations that allow them to deal with a certain level of bubble formation during normal dives, without acute adverse effects. This work evaluated the complement response, indicative of inflammation, to in vitro nitrogen bubble exposures in several marine mammal species to assess whether a less-responsive immune system serves a protective role against DCS-like injury in these animals. Serum samples from beluga (Delphinapterus leucas), and harbor seals (Phoca vitulina) (relatively shallow divers) and deep diving narwhal (Monodon monoceros), and Weddell seals (Leptonychotes weddellii) were exposed to nitrogen bubbles in vitro. Complement activity was evaluated by measuring changes in the terminal protein C5a in serum, and results suggest marine mammal complement is less sensitive to gas bubbles than human complement, but the response varies between species. Species-specific differences may be related to dive ability, and suggest moderate or shallow divers may be more susceptible to DCS-like injury. This information is an important consideration in assessing the impact of changing dive behaviors in response to anthropogenic stressors, startle responses, or changing environmental conditions that affect prey depth distributions.

The complement system may be crucial during dengue virus infection and progression to severe dengue. This study investigates the role of MBL2 genetic variants and levels of MBL in serum and complement proteins in Vietnamese dengue patients. MBL2 genotypes (- 550L/H, MBL2 codon 54), MBL2 diplotypes (XA/XO, YA/XO) and MBL2 haplotypes (LXPB, HXPA, XO) were associated with dengue in the study population. The levels of complement factors C2, C5, and C5a were higher in dengue and dengue with warning signs (DWS) patients compared to those in healthy controls, while factor D levels were decreased in dengue and DWS patients compared to the levels determined in healthy controls. C2 and C5a levels were associated with the levels of AST and ALT and with WBC counts. C9 levels were negatively correlated with ALT levels and WBC counts, and factor D levels were associated with AST and ALT levels and with platelet counts. In conclusions, MBL2 polymorphisms are associated with dengue in the Vietnamese study population. The levels of the complement proteins C2, C4b, C5, C5a, C9, factor D and factor I are modulated in dengue patients during the clinical course of dengue.

Complement (C) system is a double edge sword acting as the first line of defense on the one hand and causing aggravation of disease on the other. C activation when unregulated affects different organs including muscle regeneration. However, the effect of factor H (FH), a critical regulator of the alternative C pathway in muscle remains to be studied. FH deficiency results in excessive C activation and generates proinflammatory fragments C5a and C3a as byproducts. C3a and C5a signal through their respective receptors, C5aR and C3aR. In this study, we investigated the role of FH and downstream C5a/C5aR signaling in muscle architecture and function. Using the FH knockout (fh-/-) and fh-/-/C5aR-/double knockout mice we explored the role of C, specifically the alternative C pathway in muscle dysfunction. Substantial C3 and C9 deposits occur along the walls of the fh-/- muscle fibers indicative of unrestricted C activation. Physical performance assessments of the fh-/- mice show reduced grip endurance (76 %), grip strength (14 %) and rotarod balance (36 %) compared to controls. Histological analysis revealed a shift in muscle fiber populations indicated by an increase in glycolytic MHC IIB fibers and reduction in oxidative MHC IIA fibers. Consistent with this finding, mitochondrial DNA (mtDNA) and citrate synthase (CS) expression were both reduced indicating possible reduction in mitochondrial biomass. In addition, our results showed a significant increase in TGFβ expression and altered TGFβ localization in this setting. The architecture of cytoskeletal proteins actin and vimentin in the fh-/- muscle was changed that could lead to contractile weakness and loss of skeletal muscle elasticity. The muscle pathology in fh-/- mice was reduced in fh-/-/C5aR-/- double knockout (DKO) mice, highlighting partial C5aR dependence. Our results for the first time demonstrate an important role of FH in physical performance and skeletal muscle health., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Background: We aimed to investigate whether various immune-related plasma proteins, alone or in combination with conventional clinical risk factors, can predict spontaneous preterm delivery (SPTD) and intra-amniotic infection in women with premature cervical dilation or a short cervix (≤ 25 mm)., Methods: This retrospective study included 80 asymptomatic women with premature cervical dilation (n = 50) or a short cervix (n = 30), who underwent amniocentesis at 17-29 weeks. Amniotic fluid (AF) was cultured, and maternal plasma was assayed for interleukin (IL)-6, matrix metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinases (TIMP)-1, and complements C3a and C5a, using enzyme-linked immunosorbent assay (ELISA) kits. The primary outcome measures were SPTD at < 32 weeks and positive AF cultures., Results: The plasma levels of IL-6, C3a, and C5a, but not of MMP-9 and TIMP-1, were significantly higher in women with SPTD at < 32 weeks than in those who delivered at ≥ 32 weeks. The women who delivered at < 32 weeks had more advanced cervical dilatation, and higher rates of antibiotic and tocolytic administration and were less likely to be given vaginal progesterone than those who delivered at ≥ 32 weeks. Using a stepwise regression analysis, a combined prediction model was developed, which included the plasma IL-6 and C3a levels, and cervical dilatation (area under the curve [AUC], 0.901). The AUC for this model was significantly greater than that for any single variable included in the predictive model. In the univariate analysis, plasma IL-6 level was the only significant predictor of intra-amniotic infection., Conclusion: In women with premature cervical dilation or a short cervix, maternal plasma IL-6, C3a, and C5a levels could be useful non-invasive predictors of SPTD at < 32 weeks. A combination of these biomarkers and conventional clinical factors may clearly improve the predictability for SPTD, as compared with the biomarkers alone. An increased plasma level of IL-6 predicted intra-amniotic infection., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2020 The Korean Academy of Medical Sciences.)

Sepsis is a major cause of death in hospitalised patients accounting for mortality rates as high as 60% and, hence, is called 'a hidden public health disaster'. Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis is not a disease but is a clinical syndrome, where the initial features are nonspecific resulting in delayed diagnosis. Lack of specific laboratory tests to diagnose the syndrome adds to the diagnostic confusion. Failure to identify sepsis in the early stages itself delays effective treatment resulting in high morbidity and mortality. Various biomarkers and newer laboratory tests help to address these issues. However, to date there is no ideal test to diagnose sepsis. The most commonly used markers are C-reactive protein (CRP) and procalcitonin (PCT). There are around 180 biomarkers reported to be useful in sepsis. In addition to CRP and PCT, various emerging laboratory markers, such as like serum amyloid A, soluble triggering receptor expressed on myeloid cell-1, mannan and antimannan antibodies, and interferon γ inducible protein-10 etc., have been reviewed and their clinical usefulness discussed in this paper., Competing Interests: No conflict of interests declared

Background: Complement activation plays a substantial role in the pathogenesis of primary membranous nephropathy (pMN). C5b-9, C3c, MBL, and factor B have been documented in the subepithelial immune deposits. However, the changing of complement activation products in circulation and urine is not clear., Methods: We measured the circulating and urinary levels of C1q, MBL, C4d, Bb, properdin, C3a, C5a, and sC5b-9, in 134 patients with biopsy-proven pMN, by enzyme-linked immunosorbent assay. All the plasma values were corrected by eGFR and all the urinary values were corrected by urinary creatinine and urinary protein excretion. Anti-PLA2R antibodies were measured in all patients., Results: The plasma complement activation products were elevated both in the patients with and without anti-PLA2R antibodies. C3a levels were remarkably increased in the circulation and urine, much higher than the elevated levels of C5a. C5b-9 was in normal range in plasma, but significantly higher in urine. The urinary C5a had a positive correlation with anti-PLA2R antibody levels and urinary protein. The plasma level of C4d was elevated, but C1q and MBL were comparable to healthy controls. Positive correlations were observed between plasma C4d/MBL and urinary protein, only in the patients with positive anti-PLA2R antibodies but not in those without. The plasma level of Bb was elevated and had positive correlation with urinary protein only in the patients without anti-PLA2R antibodies., Conclusion: Complement activation products were remarkable increased in pMN and may serve as sensitive biomarkers of disease activity. The complement may be activated through lectin pathway with the existence of anti-PLA2R antibodies, while through alternative pathway in the absence of antibody.

Background: Cardiopulmonary bypass can result in lung injury. This prospective, double-blinded, randomized trial aimed to evaluate the protective effect of inhaled budesonide on lung injury after cardiopulmonary bypass., Methods: Sixty patients, aged 25 to 65 years, requiring cardiopulmonary bypass were randomized to groups treated with saline or budesonide inhalation preoperatively. The respiratory mechanics were recorded. Bronchoalveolar lavage fluid was collected before cardiopulmonary bypass and after sternal closure. Serum and bronchoalveolar lavage fluid levels of proinflammatory and anti-inflammatory factors were analyzed. The primary end point was the lowest ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen after cardiopulmonary bypass. The durations of ventilation and postoperative recovery time were noted., Results: Budesonide significantly improved respiratory mechanics after cardiopulmonary bypass. Budesonide improved the partial pressure of arterial oxygen to the fraction of inspired oxygen ratio from 8 to 48 hours after the operation. Budesonide shortened the durations of mechanical ventilation and postoperative recovery time. Budesonide decreased the levels of proinflammatory factors while increasing the levels of anti-inflammatory factors in bronchoalveolar lavage fluid and serum (all P < .05). The macrophage and neutrophil counts, and protein and elastase concentrations were decreased by budesonide treatment., Conclusions: Budesonide treatment shortened the durations of mechanical ventilation, inhibited local and systemic inflammation, and improved respiratory function after cardiopulmonary bypass., (Copyright © 2018 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Complement protein C5a is recognized as an important component of the alternative complement pathway. Its role is prominent enough to garner interest not only as a biomarker, but also as a potential therapeutic target. Bioanalytical challenges have been posed in proper quantitation of free C5a due to interference from its precursor, C5. Additionally, free therapeutic target quantitation can be difficult due to effects of sample dilution and prolonged sample incubation when therapeutic is used as capture reagent. Gyrolab technology enables quantitation of free target analyte with minimal sample dilution and rapid sample incubations, thus enabling in vitro results that are more representative of in vivo pharmacodynamics. When coupled with strategic sample pretreatment, Gyrolab offers an opportunity to quantitate free C5a in human plasma with an assay that vastly diminishes C5 interference. A Gyrolab assay for the quantitation of free C5a in human plasma was developed and validated. Validation results confirmed that proper sample pretreatment and use of the Gyrolab platform yield accurate and reliable results. Due to the advantages that it provides, Gyrolab has become our default technology of choice for quantitation of free target.

Background: Despite the heavy purulence observed in hidradenitis suppurativa (HS), the kinetics of complement anaphylatoxins acting to prime chemotaxis of neutrophils has not been studied., Objectives: To explore complement activation in HS., Methods: Circulating concentrations of complement factor C5a, as well as of membrane attack complex C5b-9, were determined in the plasma of 54 treatment-naïve patients and of 14 healthy controls, as well as in the pus of seven patients. Results were correlated with Hurley stage and International Hidradenitis Suppurativa Severity Score. Peripheral blood mononuclear cells (PBMCs) were isolated from seven patients with Hurley stage III HS and seven healthy volunteers and stimulated in the presence of 25% of plasma for the production of tumour necrosis factor-α (TNF-α)., Results: Circulating C5a and C5b-9 were significantly greater in patient than in control plasma; however, concentrations in pus were very low. Circulating C5a levels exceeding 28 ng mL -1 were associated with a specificity > 90% with the occurrence of HS. Circulating levels of C5a and C5b-9 were greater in patients with more severe HS. PBMCs of patients produced high concentrations of TNF-α only when growth medium was enriched with patient plasma; this was reversed with the addition of the C5a blocker IFX-1., Conclusions: Systemic complement activation occurs in HS and may be used as a surrogate biomarker of HS. C5a stimulates overproduction of TNF-α and may be a future therapeutic target., (© 2018 The Authors. British Journal of Dermatology published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.)

Background: We investigated whether various inflammatory and immune proteins in plasma predict intra-amniotic infection and imminent preterm delivery in women with preterm labor and compared their predictive ability with that of amniotic fluid (AF) interleukin (IL)-6 and serum C-reactive protein (CRP)., Methods: This retrospective cohort study included 173 consecutive women with preterm labor who underwent amniocentesis for diagnosis of infection and/or inflammation in the AF. The AF was cultured, and assayed for IL-6. CRP levels and cervical length by transvaginal ultrasound were measured at the time of amniocentesis. The stored maternal plasma was assayed for IL-6, matrix metalloproteinase (MMP)-9, and complements C3a and C5a using ELISA kits. The primary and secondary outcome criteria were positive AF cultures and spontaneous preterm delivery (SPTD) within 48 h, respectively. Univariate, multivariate, and receiver operating characteristic analysis were used for the statistical analysis., Results: In bivariate analyses, elevated plasma IL-6 level was significantly associated with intra-amniotic infection and imminent preterm delivery, whereas elevated plasma levels of MMP-9, C3a, and C5a were not associated with these two outcomes. On multivariate analyses, an elevated plasma IL-6 level was significantly associated with intra-amniotic infection and imminent preterm delivery after adjusting for confounders, including high serum CRP levels and short cervical length. In predicting intra-amniotic infection, the area under the curve (AUC) was significantly lower for plasma IL-6 than for AF IL-6 but was similar to that for serum CRP. Differences in the AUCs between plasma IL-6, AF IL-6, and serum CRP were not statistically significant in predicting imminent preterm delivery., Conclusions: Maternal plasma IL-6 independently predicts intra-amniotic infection in women with preterm labor; however, it has worse diagnostic performance than that of AF IL-6 and similar performance to that of serum CRP. To predict imminent preterm delivery, plasma IL-6 had an overall diagnostic performance similar to that of AF IL-6 and serum CRP. Plasma MMP-9, C3a, and C5a levels could not predict intra-amniotic infection or imminent preterm delivery.

Aim: Nonalcoholic fatty liver disease (NAFLD) is a leading cause of progressive and chronic liver injury. Complement factor 5a (C5a) may be involved in many inflammation disorders. This study investigated levels of systemic C5a in patients with and without NAFLD and lean controls., Methods: A cross-sectional study was conducted from July 2012 to June 2013 among 96 Chinese children, aged 6-17 years, recruited from the Pediatric Department of the Second Affiliated Hospital of Xi'an Jiao Tong University: 40 obese children with NAFLD, 31 obese children without NAFLD and 25 lean controls. Anthropometric parameters, clinical data and circulating C5a levels were measured., Results: Obese children had higher serum concentrations of complement factor C5a compared with lean controls, especially in obese children with NAFLD. C5a was positively correlated with body mass index (BMI), waist circumference, diastolic blood pressure (BP), triglycerides and homoeostasis model of insulin resistance, independent of their body mass index standard deviations score and age. Of the well-known risk factors, C5a was a significant predictor of NAFLD in obese children., Conclusion: Serum C5a was elevated in obese children, especially in those with NAFLD and it may be proposed as a novel marker to predict advanced disease., (©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.)

Background: Elizabethkingia miricola is a rare Gram-negative bacterium found in water and clinical specimens. Typical culturing methods often misidentify Elizabethkingia spp. as Flavobacterium or Chryseobacterium. Although diagnosis is based on culturing samples taken from sterile sites, such as blood, a proper identification of this bacterium requires an expertise that goes beyond the capabilities of a typical clinical laboratory., Case Presentation: A 35-year-old woman diagnosed with common variable immunodeficiency was admitted to our center. Previous treatment with antibiotics (amoxicillin plus clavulanate, first and third generation of cephalosporins, macrolides) and systemic corticosteroids (up to 120 mg/day of prednisolone) failed to arrest the spread of inflammation. Gingival recession was observed in her oral cavity, resulting in an apparent lengthening of her teeth. In addition to typical commensal bacteria, including streptococci and neisseriae, strains of Rothia mucilaginosa and Elizabethkingia miricola were identified upon a detailed microbiological examination using a MALDI-TOF MS Biotyper system. The presence of the latter strain correlated with severe periodontitis, lack of IgA in her saliva and serum, a very low IgG concentration (< 50 mg/dl), IgM-paraproteinemia, decreases in C3a and C5a and microvascular abnormality. High-dose immunoglobulin (to maintain IgG > 500 mg/dl) and targeted levofloxacin treatment resulted in immune system reconstitution, oral healing, and eradication of the Elizabethkingia infection., Conclusions: E. miricola rarely causes disease in healthy individuals. However, the overgrowth of commensal bacteria, lack of IgG/IgA, microvasculopathy and complement cascade activation in patients with humoral immunodeficiency may facilitate Elizabethkingia invasion. Overuse of antibiotics, particularly beta-lactams, may cause mucosal colonization by E. miricola, followed by its multiplication combined with periodontitis that prompts bacterial translocation. MALDI-TOF Biotyper analysis may become a method of choice for identification of Elizabethkingia infections.

Background: Therapeutic hypothermia (HT) is the only intervention that improves outcomes in neonatal hypoxic-ischemic encephalopathy (HIE). However, the multifactorial mechanisms by which HT impacts HIE are incompletely understood. The complement system plays a major role in the pathogenesis of ischemia-reperfusion injuries such as HIE. We have previously demonstrated that HT modulates complement activity in vitro., Methods: Term equivalent rat pups were subjected to unilateral carotid ligation followed by hypoxia (8% O2) for 45 min to simulate HIE. A subset of animals was subjected to HT (31-32°C for 6 h). Plasma and brain levels of C3a and C5a were measured. Receptors for C3a (C3aR) and C5a (C5aR) along with C1q, C3, and C9 were characterized in neurons, astrocytes, and microglia., Results: We found that HT increased systemic expression of C3a and decreased expression of C5a after HIE. In the brain, C3aR and C5aR are predominantly expressed on microglia after HIE. HT increased local expression of C3aR and decreased expression on C5aR after HIE. Furthermore, HT decreased local expression of C1q, C3-products, and C9 in the brain., Conclusion: HT is associated with significant alteration of complement effectors and their cognate receptors. Complement modulation may improve outcomes in neonatal HIE.

Objective: The aim of this study was to detect the spectrum of complement activation pathways in circulation and to assess their correlations with clinical and pathologic features in a large lupus nephritis cohort from China., Materials and Methods: Plasma levels of C1q, mannose-binding lectin, C4d, Bb, C3, C3a, C5a and soluble C5b-9 were detected by enzyme-linked immunosorbent assay in 222 patients with active biopsy-proven lupus nephritis, 34 patients with lupus nephritis at remission, 82 patients with active systemic lupus erythematosus without renal involvement and 39 normal controls. The correlations between levels of complement components and clinicopathological features of these patients were further analyzed., Results: Plasma levels of C1q and C3 significantly decreased, and the levels of Bb, C3a, C5a and soluble C5b-9 were significantly elevated in patients with active lupus nephritis compared with those in remission, active systemic lupus erythematosus without renal involvement group and normal controls. In the lupus nephritis group, soluble C5b-9 levels were inversely correlated with C1q and C4d levels (r = -0.412, P < 0.001 and r = -0.221, P = 0.002, respectively), but more strongly correlated with the level of Bb (r = 0.546, P < 0.001). C3b, Bb and C5b-9 could colocalize on glomeruli in lupus nephritis. Plasma Bb level was significantly correlated with some renal disease activity indices and was a risk factor for renal outcomes (hazard ratio = 1.745; 95% CI: 1.106-2.754; P = 0.017) in the lupus nephritis group., Conclusions: Our findings suggested that the activation of the complement alternative pathway might play a more important role in the pathogenesis of lupus nephritis, and factor Bb might be a useful marker for evaluating renal disease activity and outcomes., (Copyright © 2017 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.)

Purpose: To investigate the association between serum complement 5a (C5a) concentration and liver fibrosis and cirrhosis in a large cohort of patients chronically infected with hepatitis B virus (HBV)., Methods: Five hundred and eight patients with chronic HBV infection undergoing liver biopsy were included. Serum concentrations of C5a was measured by Luminex screening system. Ishak histological system was obtained., Results: C5a levels were negatively associated with liver fibrosis stages and significantly declined in patients with severe fibrosis and cirrhosis (P < 0.001). Multiple analysis showed C5a, AST, laminin, Co-IV, platelet count, albumin, HBsAg associated with liver fibrosis independently. Based on the markers above, we created two scores, Fib-model for significant fibrosis and Cirrh-model for earlier cirrhosis. Fib-model was performing better to differentiate from significant fibrosis, with an AUROC of 0.82 (95 % CI 0.78, 0.86), in comparison to existed models APRI, FIB-4 and Forns' index with AUROCs of 0.71 (95 % CI 0.66, 0.76), 0.72 (95 % CI 0.67, 0.77), 0.77 (95 % CI 0.72, 0.81), respectively. Although, Cirrh-model showed AUROC of 0.85 (95 % CI 0.80, 0.91) for evaluation of earlier cirrhosis, superior to APRI, and Forns' index, C5a + FIB-4 performed best with an AUROC of 0.94 (95 % CI 0.90, 0.97)., Conclusion: In patients with chronic HBV infection, serum C5a concentration significantly decreased in severe fibrosis stages and earlier cirrhosis. Fib-model and C5a + FIB-4 performed better than existed models for assessment of significant fibrosis and earlier cirrhosis, respectively., Competing Interests: Compliance with ethical standardsConflict of interestNone.FundingThis study was supported by China Mega-Project for Infectious Diseases (Grant Numbers 2013ZX10002005, 2012ZX10002006, 2013ZX10002004, 2012ZX10005005), Project of Beijing Science and Technology Committee (Grant Number D121100003912002).

Anaphylatoxin C5a and its receptor C5aR on cancer cells constitute a vital axis to cancer progression. In this study, we measured C5aR level by immunohistochemistry in the same cohort of our previous C5a research, and C5a-C5aR axis status was determined by synthesizing C5a and C5aR data. C5aR was an adverse independent prognostic factor for ccRCC patients. Kaplan-Meier analyses revealed the unique position of both C5a and C5aR high population in postoperative survival, based on which patients were then shunted into C5a-C5aR enriched and non-enriched groups. Obviously, C5a-C5aR enriched patients significantly had a poorer overall survival (OS) and recurrence free survival (RFS) compared with non-enriched ones, and the independence of C5a-C5aR axis was verified by multivariable analyses (HR 2.118, P = 0.001 for OS, HR 1.715, P = 0.035 for RFS). Established nomograms based on our findings reflected much better predicting accuracy in contrast with most common used TNM and Fuhrman systems. Meanwhile, consistent with HR, C5a-C5aR axis in this study held its advantages over C5a and C5aR for OS prediction by c-index analyses, rather than RFS prediction.

Placental ischemic disease and adverse pregnancy outcomes are frequently observed in patients with antiphospholipid syndrome (APS). Despite the administration of conventional antithrombotic treatment a significant number of women continue to experience adverse pregnancy outcomes, with uncertain prevention and management. Efforts to develop effective pharmacological strategies for refractory obstetric APS cases will be of significant clinical benefit for both mothers and fetuses. Although the antimalarial drug, hydroxychloroquine (HCQ) is increasingly used to treat pregnant women with APS, little is known about its efficacy and mechanism of action of HCQ. Because complement activation plays a crucial and causative role in placental ischemia and abnormal fetal brain development in APS we hypothesised that HCQ prevents these pregnancy complications through inhibition of complement activation. Using a mouse model of obstetric APS that closely resembles the clinical condition, we found that HCQ prevented fetal death and the placental metabolic changes -measured by proton magnetic resonance spectroscopy in APS-mice. Using 111 In labelled antiphospholipid antibodies (aPL) we identified the placenta and the fetal brain as the main organ targets in APS-mice. Using this same method, we found that HCQ does not inhibit aPL binding to tissues as was previously suggested from in vitro studies. While HCQ did not affect aPL binding to fetal brain it prevented fetal brain abnormal cortical development. HCQ prevented complement activation in vivo and in vitro. Complement C5a levels in serum samples from APS patients and APS-mice were lower after treatment with HCQ while the antibodies titres remained unchanged. HCQ prevented not only placental insufficiency but also abnormal fetal brain development in APS. By inhibiting complement activation, HCQ might also be an effective antithrombotic therapy., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objective: To investigate the expression of complement system's activation factors in plasma of patients with severe preeclampsia and their correlations with anti-angiogenesis factors., Methods: A case-control study was performed. The study group consisted of 30 cases of early-onset severe preeclampsia (EOSPE) and 30 cases of late-onset severe preeclampsia (LOSPE). Thirty cases were selected as the early-onset control group (E-control) and 30 as the late-onset control group (L-control), with the weeks of gestation matched. Enzyme-linked immunosorbent assay (ELISA) was used to test C3a, C5a, MAC, sEng, and sflt-1 in the maternal peripheral circulation., Results: The complement system's activation factors C3a, C5a, and MAC were increased significantly in EOSPE and LOSPE (all P < 0.01) compared with E/L-control. Plasma levels of C3a correlated inversely with plasma sEng (r = -0.454, P < 0.001) and sflt-1 (r = -0.326, P = 0.011) in preeclampsia patients, while MAC correlated with soluble endoglin (sEng; r = 0.343, P = 0.007) and soluble fms-like tyrosine kinase-1 (sflt-1; r = 0.318, P = 0.013). There were no significant correlations between complement system's activation-related factors and the anti-angiogenesis factors in healthy control group., Conclusions: Abnormal activation of the complement system exists in the maternal circulation of patients with E/L-onset severe preeclampsia. There were correlations between the abnormal activation of the complement system and the abnormal expression of anti-angiogenesis factors in patients with severe preeclampsia, but the correlation was not strong.

Background: Recent studies were able to demonstrate involvement of the complement cascade in bone biology. Further studies analyzed the role of complement in traumatic injuries and demonstrated negative effects after excessive systemic activation of the inflammatory response with early abrogation of complement activation after application of a C5aR-antagonist exerting beneficial effects upon bone regeneration. In contrast, own fracture healing experiments with complement-deficient animals implied a crucial role of the complement cascade for sufficient fracture healing., Methods: To analyze the effect of a short abrogation of the complement system in the local process of fracture healing, a fracture healing experiment with wild-type mice (C57BL6), femoral osteotomy, consecutive external fixation for 21 days and blockade of the early complement activation (C5aRA) directly after trauma and after 12 h was performed. Control animals received a peptide without any biological effects. After 1-3 days, the inflammatory response was monitored with IL-6 immunostaining, serum analyses of C5a and after 3 days with histological evaluation of PMN. Fracture healing was examined with biomechanical, radiological and histological methods after 21 days., Results: While a decrease of the early inflammatory response was seen on day 1 of the C5aRA-treated group regarding immunostaining for IL-6 and after 3 days in the histological evaluation of PMN, no significant differences were demonstrated between both experimental groups after 21 days in the biomechanical, radiological and histological evaluation., Conclusions: The present results demonstrate that the short-term inhibition of complement activation immediately after fracture does not significantly affect bone regeneration in an experimental model of regular fracture healing. Whereas other studies demonstrated that the early posttraumatic blockade of the C5aR improves fracture healing in a scenario of combined trauma, the present findings implicate that the same treatment has no effect in uneventful bone healing.

Enhanced levels of platelet/granulocyte aggregates (PGAs) are found in patients suffering from many different inflammatory vascular diseases, and their formation in animal models of vascular disease is associated with increased thromboinflammation and worsened outcomes. The complement system, a part of the innate immune system, influences PGA formation, but the mechanisms for its effects are unknown. In this study, we have defined complement-mediated mechanisms that enhance PGA formation in human whole blood stimulated with thrombin receptor-activating peptide (TRAP) using ex vivo flow cytometry assays. We demonstrate that physiological properdin, a positive regulator of complement alternative pathway activity, increases PGA formation when added to TRAP-stimulated blood. All physiological properdin forms increase PGA formation, but properdin tetramers are the most efficient at increasing complement activity and PGA formation. Inhibition of endogenous properdin, either circulating in the blood or produced locally by leukocytes, impairs TRAP-mediated PGA formation to the same level as specific inhibition of either the alternative or classical pathway. Additionally, blocking the interaction of C5a with its cellular receptor prevents properdin-mediated increases in PGA formation. Adding either properdin tetramers or C5a to whole blood increases CD11b expression on granulocytes, and this increase is prevented by blockade of the C5a-C5a receptor axis. Finally, we demonstrate that the effects of properdin on PGA formation are tightly regulated by Factor H. Cumulatively, our data indicate that properdin enhances PGA formation via increased production of C5a, and that inhibition of properdin function has therapeutic potential to limit thromboinflammation in diseases characterized by increased PGA formation., (Copyright © 2016 by The American Association of Immunologists, Inc.)

Objective: To investigate the effect of Liuwei Wuling tablets on the cytoplasmic translocation and release of high-mobility group box-1 (HMGB1) in hepatocytes in mice with acute live injury induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS)., Methods: A Balb/c mouse model of acute liver injury was established by intraperitoneal injection of D-GalN (400 mg/kg) and LPS (5 ug/kg). A total of 24 healthy mice were randomly and equally divided into acute liver injury control group and Liuwei Wuling tablet treatment group. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured in both groups at each time point within one week. Liver tissues were collected at 36 hours to perform pathological examination. The serum levels of HMGB1, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), complement 3a (C3a), and complement 5a (C5a) were measured. Immunohistochemistry was used to determine the expression and cytoplasmic translocation of HMGB1 in hepatocytes., Results: At 6, 12, and 24 hours, the Liuwei Wuling tablet treatment group had significantly lower serum levels of ALT than the control group (225.33±181.64 U/L vs 471.17±174.72 U/L, t = 3.38, P < 0.01; 1509.53±182.51 U/L vs 7149.52±734.25 U/L, t = 25.82, P < 0.01; 162.89±86.51 U/L vs 1318.16±557.71 U/L, t = 7.09, P < 0.01), as well as significantly lower serum levels of AST than the control group (179.22±94.57 U/L vs 561.91±209.6 U/L, t = 5.76, P < 0.01; 590.92±190.92 U/L vs 2266.48±705.64 U/L, t = 7.94, P < 0.01; 231.24±87.7 U/L vs 444.32±117.01 U/L, t = 5.05, P < 0.01). The treatment group had significantly lower levels of HMGB1 than the control group at 6 and 12 hours (54.21±11.89 ng/ml vs 72.07±13.65 ng/ml, t = 3.41, P < 0.01; 49.23±5.97 ng/ml vs 68.71±13.07 ng/ml, t = 4.70, P < 0.01). The treatment group had significantly lower levels of TNF-α, IL-1β, and IL-6 than the control group at 12 hours (163.62±9.12 pg/ml vs 237.09±51.47 pg/ml, t = 4.86, P < 0.01; 15.66±13.13 pg/ml vs 37.43±18.68 pg/ml, t = 3.30, P < 0.01; 7.10±3.06 pg/ml vs 21.42±8.23 pg/ml, t = 5.65, P < 0.01). The treatment group had significantly lower levels of C3a and C5a than the control group at 12 hours (2.52±1.27 pg/ml vs 9.83±2.96 ng/ml, t = 7.86, P < 0.01; 2.16±1.03 ng/ml vs 7.23±1.55 ng/ml, t = 9.67, P < 0.01). Compared with the control group, the treatment group had significantly reduced liver inflammation and necrosis, and a significantly lower cytoplasmic translocation rate of HMGB1 in hepatocytes (38.76%±7.37% vs 8.15%±2.11%, P < 0.01)., Conclusion: Liuwei Wuling tablets can reduce the cytoplasmic translocation of HMGB1 in hepatocytes and relieve liver inflammation in mice with acute liver injury.

Objective: Inhibition of components of the complement system or of its receptors has been postulated as a concept for primary and secondary prevention in atherosclerosis and was applied in clinical trials. Although the anaphylatoxin-receptors C3aR and C5aR are commonly associated with inflammatory cells, in vitro studies suggested their expression also on platelets., Methods and Results: Expression levels of C3aR and C5aR were measured by flow cytometry in a collective of 302 patients with documented coronary artery disease (CAD) including patients with stable CAD (n = 152), unstable angina (n = 54), acute myocardial infarction (AMI; Non-ST elevation myocardial infarction, n = 70, ST elevation MI, n = 26) or healthy controls (n = 21). Patients with stable CAD, unstable angina or AMI had significantly higher expression of C5aR on platelets in comparison to healthy controls (MFI 14.68 (5.2), 14.56 (5.18) and 13.34 (4.52) versus 10.68 (3.1)); p < 0.001). In contrast, the expression of C3aR on platelets was significantly enhanced in patients with stable and unstable CAD but not in patients with AMI compared to controls. While there was a strong correlation between the soluble ligands of these receptors C3a and C5a, we observed only a weak correlation with their receptors on platelets. Similarly, agonist induced aggregation (MEA, ADP, and TRAP) showed only a weak correlation with the expression level of anaphylatoxin - receptors on platelets. Of note, the expression of both anaphylatoxin-receptors on platelets strongly correlated with platelet activation as assessed with the surface activation marker P-selectin (r = 0.47, p > 0.001 for C3aR, r = 0.76 for C5aR, p < 0.001). Likewise, we observed a positive correlation of C3aR with other molecules associated with platelet activation such as SDF-1., Conclusion: In summary, we observed a positive correlation between the expression of anaphylatoxin-receptors C3aR and C5aR with platelet activation in patients with CAD. Further investigations are needed to study the clinical and mechanistic relevance of these findings., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Background: Antimicrobial peptides (AMP) are an important defense mechanism of the innate immune system and can modulate the course of various diseases. However, their significance during liver pathogenesis is currently not well defined., Methods: Patients with liver diseases were analyzed for LL-37/CRAMP, human beta-defensin-2 (hBD2), and complement 5a (C5a) serum levels. Mice deficient in CRAMP (Cathelicidin-related Antimicrobial Peptide), the mouse homolog for human LL-37, were fed with a methionine- and choline-deficient diet (MCD) and underwent bile-duct ligation (BDL)., Results: First, serum samples from patients with chronic liver diseases were investigated. Therefore, significantly enhanced levels for LL-37, hBD2, and complement C5a were detected, all of which comprise antimicrobial properties. Next, CRAMP-knockout (CRAMP-KO) mice were investigated, to better define a functional role of LL-37/CRAMP in animal models of liver diseases. MCD feeding and bile-duct ligation of CRAMP-KO mice resulted in an enhanced degree of liver injury during the early treatment phase. MCD feeding in CRAMP-KO mice led to stronger intrahepatic fat accumulation and significantly enhanced matrix remodeling, whereas BDL caused more extensive liver necrosis. At the late 28 days time point, MCD-fed CRAMP-KO mice displayed a higher intrahepatic fat load. Long-term changes in bile-duct-ligated mice included higher collagen content as a sign of enhanced fibrosis progression if CRAMP was absent., Conclusion: The study shows a clear correlation of antimicrobial peptide serum levels in patients with chronic liver diseases. Furthermore, we were able to demonstrate protective functions of LL-37/CRAMP in two independent mouse models of chronic liver injury.

A role for NKT cells has been implicated in sepsis, but the mechanism by which NKT cells contribute to sepsis remains unclear. Here, we examined WT and NKT-cell-deficient mice of C57BL/6 background during cecal ligation and puncture-induced sepsis. The levels of C5a, IFN-γ, and IL-10 were higher in the serum and peritoneal fluid of WT mice than in those of CD1d(-/-) mice, while the mortality rate was lower in CD1d(-/-) mice than in WT mice. C5a blockade decreased mortality of WT mice during sepsis, whereas it did not alter that of CD1d(-/-) mice. As assessed by intracellular staining, NKT cells expressed IFN-γ, while neutrophils expressed IL-10. Upon coculture, IL-10-deficient NKT cells enhanced IL-10 production by WT, but not IFN-γR-deficient, neutrophils. Meanwhile, CD1d(-/-) mice exhibited high CD55 expression on neutrophils during sepsis, whereas those cells from WT mice expressed minimal levels of CD55. Recombinant IL-10 administration into CD1d(-/-) mice reduced CD55 expression on neutrophils. Furthermore, adoptive transfer of sorted WT, but not IFN-γ-deficient, NKT cells into CD1d(-/-) mice suppressed CD55 expression on neutrophils, but increased IL-10 and C5a levels. Taken together, IFN-γ-producing NKT cells enhance C5a generation via IL-10-mediated inhibition of CD55 expression on neutrophils, thereby exacerbating sepsis., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Atypical hemolytic uremic syndrome (aHUS) is characterized by dysregulated complement activity, the development of a thrombotic microangiopathy (TMA), and widespread end organ injury. aHUS remains a clinical diagnosis without an objective laboratory test to confirm the diagnosis. We performed a retrospective analysis of 103 patients enrolled in the Ohio State University TTP/aHUS Registry presenting with an acute TMA. Nineteen patients were clinically categorized as aHUS based on the following criteria: (1) platelet count <100 × 10(9)/L, (2) serum creatinine >2.25 mg/dL, and (3) a disintegrin and metalloprotease with thrombospondin type 1 motif, 13 (ADAMTS13) activity >10%. Sixteen of 19 patients were treated with plasma exchange (PEX) therapy, with 6/16 (38%) responding to PEX. Nine patients were treated with eculizumab with 7/9 (78%) responding to therapy. In contrast to thrombotic thrombocytopenic purpura (TTP) patients, no aHUS patients demonstrated ultralarge von Willebrand factor multimers at presentation. Median markers of generalized complement activation (C3a), alternative pathway (Bb), classical/lectin pathway (C4d), and terminal complement activation (C5a and C5b-9) were increased in the plasma of these 19 patients. Compared with a cohort of ADAMTS13-deficient TTP patients (n = 38), C5a and C5-9 were significantly higher in the 19 patients clinically characterized as aHUS, suggesting that pretreatment measurements of complement biomarkers C5a and C5b-9 may confirm the diagnosis of aHUS and differentiate it from TTP., (© 2014 by The American Society of Hematology.)

Background: Pulmonary contusion (PC) is a common, potentially lethal injury that results in the priming for exaggerated responses to subsequent immune challenge such as an infection (second hit). We hypothesize a PC-induced complement (C) activation participates in the priming effect for a second hit., Methods: Male, 8 weeks to 9 weeks, C57BL/6 mice (wild-type, C5) underwent blunt chest trauma resulting in PC. At 3 hours/24 hours after injury, the inflammatory response was measured in tissue, serum, and bronchoalveolar lavage (BAL). The thrombin inhibitor, hirudin, was used to determine if injury-induced thrombin participated in the activation of C. Injury-primed responses were tested by challenging injured mice with bacterial endotoxin (lipopolysaccharide, LPS) as a second hit. Inflammatory responses were assessed at 4 hours after LPS challenge. Data were analyzed using one-way analysis of variance with Bonferroni multiple comparison posttest (significance, p ≤ 0.05). Protocols were approved by the Institutional Animal Care and Use Committee., Results: We found significantly increased levels of C5a in the BAL of injured animals as early as 24 hours, persisting for up to 72 hours after injury. Hirudin-treated injured mice had significantly decreased levels of thrombin in the BAL that correlated with reduced C5a levels. Injured mice challenged with intratracheal (IT) LPS had increased C5a and inflammatory response. Conversely, inhibition of C5a or its receptor, C5aR, before LPS challenge correlated with decreased inflammatory responses; C5a-deficient mice showed a similar loss of primed response to LPS challenge., Conclusion: Complement C5a levels in the BAL are increased over several days after PC. Premorbid inhibition of thrombin markedly decreases C5a levels after PC, suggesting that thrombin-induced C activation is the major pathway of activation after PC. Similarly, inhibition of C5a after PC will decrease injury-primed responses to LPS stimulation. Our findings suggest cross-talk between the coagulation and complement systems that induce immune priming after PC.

Sulfur mustard (SM) is a strong toxic agent that causes acute and chronic health effects on a myriad of organs following exposure. Although the primary targets of inhaled mustard gas are the epithelia of the upper respiratory tract, the lower respiratory tract is the focus of the current study, and upper tract complications remain obscure. To our knowledge there is no study addressing the secretory IgA (S-IgA), C5a, alpha 1 antitrypsin (A1AT) in the saliva of SM-exposed victims. In this study, as many as 500 volunteers, including 372 SM-exposed cases and 128 control volunteers were recruited. A 3 ml sample of saliva was collected from each volunteer, and the level of secretory IgA, C5a, and alpha 1 antitrypsin in the samples were compared between the two groups. The SM-exposed group showed a significantly higher amount of salivary alpha 1 antitrypsin and secretary IgA compared to the control group (p<.006 and p<.018 respectively). The two groups showed no significant difference (p=0.192) in the level of C5a. The results also showed that the level of salivary A1AT is more than that of IgA in severely injured cases. The findings presented here provide valuable insight for both researchers and practitioners dealing with victims of the chemical warfare agent, sulfur mustard. This research indicates that certain branches of the inflammatory processes mandate serious attention in therapeutic interventions., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Preeclampsia is a leading cause of morbidity and mortality worldwide, encompassing significant short- and long-term health sequelae. Recently, there has been accumulating evidence for a role of the complement system in the pathogenesis of numerous complications of pregnancy, including preeclampsia. The present cross-sectional study compared the plasma concentrations of complement factors C3a and C5a between normotensive pregnancies and pregnancies complicated with either preeclampsia or gestational hypertension alone. We found that maternal plasma C5a concentration was significantly higher in preeclamptic pregnancy than in pregnancy affected by gestational hypertension alone or normotensive pregnancy. Umbilical cord plasma C5a concentrations were also higher in pregnancies complicated by preeclampsia compared to gestational hypertension or normotensive pregnancy. Maternal and cord plasma C5a concentrations were significantly correlated, suggesting that C5a can freely diffuse between maternal and fetal circulation. There were no significant differences in C3a concentrations in maternal or cord plasma between any groups. These results support the hypothesis that C5a may play a role in preeclampsia, but not in gestational hypertension., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

The complement anaphylatoxins C3a, C5a, and desarginated C5a (C5a(desArg)) play critical roles in the induction of inflammation and the modulation of innate and acquired immune responses after binding to their G protein-coupled receptors, C3a receptor and C5a receptor (C5aR). The role of C5a(desArg) in inducing cell activation has been often neglected, because the affinity of C5a(desArg) for C5aR has been reported to be much lower than that of C5a. We have used a novel label-free cellular assay to reassess the potential of C5a(desArg) to induce activation of transfected and primary immune cells. Our results indicate that physiological levels of C5a(desArg) induce significant levels of cell activation that are even higher than those achieved by stimulating cells with analogous concentrations of C5a. Such activation was strictly dependent on C5aR, because it was completely abrogated by PMX-53, a C5aR antagonist. Pharmacological inhibition of specific G proteins located downstream of C5aR indicated differential involvement of G(α) proteins upon C5aR engagement by C5a or C5a(desArg). Further, mass spectrometric characterization of plasma-derived C5a and C5a(desArg) provided important insight into the posttranslational modification pattern of these anaphylatoxins, which includes glycosylation at Asn(64) and partial cysteinylation at Cys(27). Although the context-specific physiological contribution of C5a(desArg) has to be further explored, our data suggest that C5a(desArg) acts as a key molecule in the triggering of local inflammation as well as the maintenance of blood surveillance and homeostatic status.

Background and Objectives: The complement cascade seems to be an important mediator modulating renal ischemia/reperfusion injury. This study analyzed whether significant changes occur in the levels of a terminal panel of complement molecules (C3a, C5a, and C5b-9/membrane attack complex) during the early phase of human kidney allograft reperfusion and evaluated the potential association of these changes with clinical post-transplant graft function in kidney transplant recipients., Design, Setting, Participants, & Measurements: Seventy-five renal transplant recipients undergoing transplantation between 2004 and 2006 were enrolled in the study and divided into early, slow, and delayed graft function groups. Blood samples were collected perioperatively during consecutive minutes of allograft reperfusion from the renal vein. Levels of complement molecules were measured using ELISA., Results: Analysis revealed no significant changes in C3a and C5a levels throughout reperfusion. The main complement molecule that was significantly associated with post-transplant graft function was C5b-9/membrane attack complex; throughout the reperfusion period, perioperative levels of C5b-9/membrane attack complex were around two to three times higher in delayed graft function patients than early and slow graft function individuals (P<0.005). In addition, C5b-9/membrane attack complex levels had a relatively high clinical sensitivity and specificity (70%-87.5%) for the prediction of early and long-term (1 year) post-transplant allograft function., Conclusions: This clinical study supports a role for the complement cascade in delayed graft function development. However, additional studies are needed to elucidate the exact mechanisms responsible for this phenomenon. In addition, perioperative measurements of C5b-9/membrane attack complex are highlighted as promising potential clinical markers of post-transplant renal allograft function.

Background: Neutrophils are one of the predominant immune cells initially migrating to surgical wound edges. They produce mediators both associated with supporting (interleukin [IL]-1β, C5a) and reducing (opioid peptides) pain. Studies demonstrate neutrophil depletion/blockade reduces nociceptive sensitization after nerve injury and carrageenan administration, but enhance sensitization in complete Freund's adjuvant inflammation. This research identifies the contribution of infiltrating neutrophils to incisional pain and inflammation., Methods: Antibody-mediated Gr1 neutrophil depletion preceded hind paw incisions. Sensitization to mechanical and thermal stimuli, effects on edema and local levels of IL-1β and C5a were measured. Local effects of C5a or IL-1 receptor antagonists PMX-53 and anakinra on sensitization after neutrophil depletion were examined. Groups of 4-8 mice were used., Results: Anti-Gr1 antibody depleted more than 90% of circulating and infiltrating skin neutrophils after incision. Neutrophil depletion did not change magnitude or duration of mechanical hypersensitivity in incised mice. However, paw edema was significantly reduced and heat hypersensitivity was slightly increased in depleted animals. In depleted animals IL-1β levels were half of controls 24 h after incision, whereas C5a levels were increased in both. Prominent IL-1β immunohistochemical staining of epidermis was seen in both groups. PMX-53 and anakinra reduced incisional mechanical and heat nociceptive sensitization to the same extent, regardless of neutrophil depletion., Conclusions: Neutrophil-derived IL-1β and C5a do not appear to contribute critically to peri-incisional nociceptive signaling. Other sources of mediators, such as epidermal cells, may need to be considered. Controlling inflammatory activation of resident cells in epidermis/deeper structures may show therapeutic efficacy in reducing pain from surgical incisions.

Introduction: The complement system is crucial for the development of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). In particular, C5a plays a central role. In this study, plasma and urinary levels of C5a as well as renal C5a receptors (CD88 and C5L2) expression were investigated in patients with AAV., Methods: Twenty-four patients with AAV in the active phase, 19 patients with AAV in the remission phase, and 20 patients with lupus nephritis (LN) were included. Plasma and urinary levels of C5a were measured with enzyme-linked immunosorbent assay (ELISA). The staining of CD88 and C5L2 in renal specimens was detected with immunohistochemistry., Results: The level of plasma C5a was significantly higher in patients with AAV in the active phase than that in patients in remission, that in patients with LN, and that in normal controls. The urinary C5a level was significantly higher in patients with AAV in the active phase than that in patients in remission and that in normal controls, but not significantly different between patients with active AAV and patients with LN. The mean optical density of CD88 staining in the tubulointerstitium was significantly lower in AAV patients than that in normal controls (0.0052 ± 0.0011 versus 0.029 ± 0.0042; P = 0.005). The mean optical density of C5L2 in glomeruli was significantly higher in AAV patients than that in normal controls (0.013 ± 0.0027 versus 0.0032 ± 0.0006; P < 0.001). The mean optical density of CD88 staining closely correlated with the initial eGFR (r = 0.835; P < 0.001) in AAV patients. Double-labeling immunofluorescence assay suggested that CD88 did not express on neutrophils, monocytes, or macrophages, but C5L2 expressed on neutrophils (or monocytes) and macrophages., Conclusion: The elevated plasma and urinary C5a levels indicated complement activation in human AAV. The level of renal CD88 expression could reflect the disease severity of ANCA-associated glomerulonephritis. CD88 expression was downregulated, and C5L2 was upregulated in ANCA-associated glomerulonephritis.

The complement component C5a is a potent inflammatory peptide, which may be involved in the pathogenesis of Chronic Obstructive Pulmonary Disease (COPD). We analysed the induced sputum and plasma of 28 patients with stable COPD, 12 healthy smokers and 7 non-smokers. In 13 of the patients with COPD, we also observed paired samples during acute exacerbation. The concentrations of C5a/C5a desArg and C3a/C3a desArg were measured using cytometric bead array. Both C5a and C3a concentrations in induced sputum of stable patients with COPD were significantly increased compared to the control groups of healthy smokers and non-smokers. In addition, there was a significant elevation in C5a values in exacerbation of COPD that was independent from the airway C3a levels. Airway C5a levels were negatively correlated with forced expiratory volume in first second (FEV1)% predicted and diffusing capacity of the lung (TLCO). Plasma C5a concentrations in patients with COPD were significantly higher than in healthy smokers, but no further significant systemic C5a elevation was detected with acute exacerbation of COPD. There was no important difference in local or systemic C5a concentrations between healthy smokers and non-smokers. These in vivo results clearly show that local and systemic C5a concentrations in COPD are elevated, and that the local, in contrast to systemic, C5a concentrations additionally increase in the acute exacerbation of COPD. It seems that the cigarette smoke is not related to C5a increase. The elevated local and systemic C5a levels, and additional individual local C5a increase during the exacerbation support the importance of C5a in COPD.

Objectives: This study assessed the extent and mechanism of complement activation in community-acquired sepsis at presentation to the emergency department (ED) and following 24 hours of quantitative resuscitation., Methods: A prospective pilot study of patients with severe sepsis and healthy controls was conducted among individuals presenting to a tertiary care ED. Resuscitation, including antibiotics and therapies to normalize central venous and mean arterial pressure (MAP) and central venous oxygenation, was performed on all patients. Serum levels of Factor Bb (alternative pathway), C4d (classical and mannose-binding lectin [MBL] pathway), C3, C3a, and C5a were determined at presentation and 24 hours later among patients., Results: Twenty patients and 10 healthy volunteer controls were enrolled. Compared to volunteers, all proteins measured were abnormally higher among septic patients (C4d 3.5-fold; Factor Bb 6.1-fold; C3 0.8-fold; C3a 11.6-fold; C5a 1.8-fold). Elevations in C5a were most strongly correlated with alternative pathway activation. Surprisingly, a slight but significant inverse relationship between illness severity (by sequential organ failure assessment [SOFA] score) and C5a levels at presentation was noted. Twenty-four hours of structured resuscitation did not, on average, affect any of the mediators studied., Conclusions: Patients with community-acquired sepsis have extensive complement activation, particularly of the alternative pathway, at the time of presentation that was not significantly reversed by 24 hours of aggressive resuscitation.

Objective: Drug eluting stents (DES) reduce recurrent luminal narrowing through anti-migratory and anti-proliferative effects. However, recent concerns arose that DES may also induce significant chronic inflammatory responses that may impair vascular healing and lead to in-stent restenosis (ISR). As the complement components C3a and C5a exert particularly strong chemotactic and proinflammatory effects, we examined the association of serum levels of C3a and C5a and ISR after implantation of DES., Methods: We included 82 patients that were treated with 151 DES. Blood samples were taken directly before and 24h after PCI. Serum levels of C3a and C5a were measured by specific ELISA and restenosis was evaluated at 6-8 months by coronary angiography., Results: C5a but not C3a increased after implantation of DES (p<0.05). During the follow-up period, two patients (2.4%) died of cardiovascular causes and 12 patients (7.9% of stents, 15% of patients) developed ISR. Serum levels of C3a before and 24h after PCI as well as C5a levels at baseline were significantly higher in patients that developed ISR at follow-up. C3a and C5a at baseline were significantly associated to angiographic late lumen loss independent from clinical and procedural risk factors., Conclusion: Increased complement activation as measured by higher levels of C3a and C5a before PCI is significantly associated with late lumen loss. Inhibition of the complement cascade to prevent ISR warrants further investigation., (Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.)

Background and Objectives: Complement inhibition is considered important in the mechanism of action of intravenous immunoglobulin (IVIG) in a number of inflammatory and autoimmune disorders. The capacity of different IVIG preparations to 'scavenge' activated C3 and thereby inhibit complement activation was assessed by a new in vitro assay., Materials and Methods: Diluted human serum as a complement source, with or without addition of different concentrations of IVIG, was incubated in microtitre plates coated with heat-aggregated human IgG. Complement scavenging was measured by detecting reduced C3 binding and determining fluid phase C3b-IgG complex formation. Complement activation induced by the IVIG preparations was measured as C5a formation., Results: All IVIG preparations exhibited a dose-dependent inhibition of C3b deposition, correlating strongly with binding of C3b to fluid-phase IgG, but the extent of complement scavenging varied considerably between different IVIG preparations. At an IVIG concentration of 0.9 mg/ml, the inhibition of C3b deposition ranged from 72 +/- 16% to 22 +/- 4.1%. The reduction of C3b deposition on the complement-activating surface was not due to IVIG-induced complement activation in the fluid phase, as shown by the low C5a formation in the presence of serum., Conclusion: In vitro analysis allows comparison of the complement-inhibitory properties of IVIG preparations. The extent of complement scavenging varies between the products.