Total Complement Activity Research Articles

Immunodeficiency: Complement disorders.

The complement system is an important component of innate and adaptive immunity that consists of three activation pathways. The classic complement pathway plays a role in humoral immunity, whereas the alternative and lectin pathways augment the innate response. Impairment, deficiency, or overactivation of any of the known 50 complement proteins may lead to increased susceptibility to infection with encapsulated organisms, autoimmunity, hereditary angioedema, or thrombosis, depending on the affected protein. Classic pathway defects result from deficiencies of complement proteins C1q, C1r, C1s, C2, and C4, and typically manifest with features of systemic lupus erythematosus and infections with encapsulated organisms. Alternative pathway defects due to deficiencies of factor B, factor D, and properdin may present with increased susceptibility to Neisseria infections. Lectin pathway defects, including Mannose-binding protein-associated serine protease 2 (MASP2) and ficolin 3, may be asymptomatic or lead to pyogenic infections and autoimmunity. Complement protein C3 is common to all pathways, deficiency of which predisposes patients to severe frequent infections and glomerulonephritis. Deficiencies in factor H and factor I, which regulate the alternative pathway, may lead to hemolytic uremic syndrome. Disseminated Neisseria infections result from terminal pathway defects (i.e., C5, C6, C7, C8, and C9). Diagnosis of complement deficiencies involves screening with functional assays (i.e., total complement activity [CH50], alternative complement pathway activity [AH50], enzyme-linked immunosorbent assay [ELISA]) followed by measurement of individual complement factors by immunoassay. Management of complement deficiencies requires a comprehensive and individualized approach with special attention to vaccination against encapsulated bacteria, consideration of prophylactic antibiotics, treatment of comorbid autoimmunity, and close surveillance.

Real-world safety profile of eculizumab: an analysis of FDA adverse event reporting system and systematic review of case reports

ABSTRACT Background Most of the safety data regarding eculizumab came from clinical trials, while its safety information in the real world is still limited. Research design and methods The data of eculizumab in the FDA Adverse Event Reporting System (FAERS) database (from the first quarter of 2007 to the first quarter of 2023) was collected and analyzed. The case reports of adverse drug reactions (ADRs) related to eculizumab in PubMed, Embase and Web of Science before May 2023 were systematically reviewed. Results A total of 464 ADRs of eculizumab were identified in the FAERS database. The top five ADRs with the highest proportional reporting ratio (PRR) are total complement activity decreased, extravascular hemolysis, hemoglobinuria, total complement activity increased and breakthrough hemolysis. Fifty-one cases of ADR related to eculizumab were identified from 44 publications. The number of reported cases of eculizumab associated Neisseria gonorrhoeae infection in case reports was observed to be comparable to the number of cases of Neisseria meningitidis infection. Conclusions Clinicians must pay close attention to the risk of infections in patients receiving eculizumab, including severe N. meningitidis infection and other potentially fatal infections such as N. gonorrhoeae infection. In addition, The possible emergence of new ADRs should be vigilant during clinical medication.

#2314 Circulating immune complexes concentration and complement activation in sensitized kidney transplant recipients

Abstract Background and Aims Chronic antibody mediated rejection of the kidney transplant is the most common cause of graft loss in the late posttransplant period. Crucial in this process seems to be the role of classical pathway complement activation due to the formation of immune complexes. The formation of immune complexes is a benign process of a normally functioning immune system. In kidney transplant recipients (KTRs), the production of donor specific IgG/IgM antibodies (DSAs) against donor antigens (MHC molecules, ABO blood group antigens) leads to the attachment of immune complexes to cell membranes and subsequent tissue damage through complement activation. The attachment of C1q complement fragment to the immune complexes holds an important part in this process. This study aims to determine the levels of immune complexes as well as classical pathway complement activation in sensitized kidney transplant recipients. Method In this cross-sectional study 3 groups of KTRs were compared as to the levels of immunocomplexes concentration and classical pathway complement activation. Fourteen KTRs with preformed or de novo donor specific antibodies were compared to 28 kidney transplant recipients with no DSAs and to 22 subjects with no history of chronic kidney disease (controls). We used MicroVue Complement CIC-C1q EIA that is designed to detect immunocomplexes that bind to C1q in human serum or plasma. In order to estimate total classical pathway complement activation in serum, we used MicroVue Complement CH50 Eq EIA. Results Kidney function (eGFR) of KTRs with and without DSAs was similar (53.1 ± vs. 60.8 ± ml/min/1.73 m2, p = 0.54) but lower in comparison to controls (106.4 ml/min/1.73 m2, p < 0.001). We found a significantly higher concentration of C1q-immunocomplexes in the serum of KTRs with donor specific antibodies, in comparison to controls, as well as to the group of kidney transplant recipients with no DSAs (6.78 ± 2.7 vs. 4.83 ± 1.9 vs. 5.04 ± 1.2 μgEq/ml respectively, p = 0.0078). Furthermore, there was no significant difference of C1q-immunocomplexes between kidney transplant recipients with no DSAs and controls. Finally, a significant reduction of CH50 levels was observed in KTRs with DSAs as compared to controls and KTRs with no DSAs (39.2 ± 14.9 vs. 70.6 ± 34.3 vs. 67.9 ± 39.9 U/ml respectively, p = 0.003), which suggests higher levels of classical pathway complement activation. CH50 levels in KTRs with DSAs, who were further subcategorized in those with preformed and those with de novo DSAs were similar (39.68 ± 15.6 vs 39.08 ± 16.04 U/ml). Conclusion Kidney transplant recipients with donor specific antibodies have increased serum levels of immune complexes and increased classical pathway complement activation.

Transient Binding Dynamics of Complement System Pattern Recognition Molecules on Pathogens.

Previous studies of pattern recognition molecules (PRMs) of the complement system have revealed difficulties in observing binding on pathogens such as Aspergillus fumigatus and Escherichia coli, despite complement deposition indicative of classical and lectin pathway activation. Thus, we investigated the binding dynamics of PRMs of the complement system, specifically C1q of the classical pathway and mannose-binding lectin (MBL) of the lectin pathway. We observed consistently increasing deposition of essential complement components such as C4b, C3b, and the terminal complement complex on A. fumigatus and E. coli. However, C1q and MBL binding to the surface rapidly declined during incubation after just 2-4 min in 10% plasma. The detachment of C1q and MBL can be linked to complement cascade activation, as the PRMs remain bound in the absence of plasma. The dissociation and the fate of C1q and MBL seem to have different mechanistic functions. Notably, C1q dynamics were associated with local C1 complex activation. When C1s was inhibited in plasma, C1q binding not only remained high but further increased over time. In contrast, MBL binding was inversely correlated with total and early complement activation due to MBL binding being partially retained by complement inhibition. Results indicate that detached MBL might be able to functionally rebind to A. fumigatus. In conclusion, these results reveal a (to our knowledge) novel "hit-and-run" complement-dependent PRM dynamic mechanism on pathogens. These dynamics may have profound implications for host defense and may help increase the functionality and longevity of complement-dependent PRMs in circulation.

Dissociation Phenomenon of Erythrocyte Agglutination and Its Application to Assay of Functional Activity of the Complement System in Clinical Laboratory.

The objective of the study was to validate the dissociation phenomenon of erythrocyte agglutination which is based on erythrocyte fragments and to apply it in the functional activity assay of the complement system. The dissociation-agglutination effect of erythrocyte fragments was validated by detecting the number of free erythrocytes after the action of erythrocyte fragments on agglutinated erythrocytes. The number of free erythrocytes produced after hemolysis of agglutinated erythrocytes caused by complements and complement activators(CAs) was detected by auto hematology analyzer and the results were indicated by mean hemoglobin concentration of erythrocytes (MCHC). We optimized the test conditions and validated the inter-batch stability, explored the resolution of the assay method, and assayed for the total complement activity (AC) and the CAs activated complement activity (ACA) in serum from patients and healthy individual groups. Erythrocyte fragments have a dissociative effect on agglutinated erythrocytes. The auto hematology analyzer was able to detect AC and ACA, where AC showed an inverse correlation with MCHC, and ACA demonstrated a positive correlation with MCHC. The inter-batch CV of AC, ACA, and ACA/AC was found to be 5%, 9%, and 11.7%, respectively, with good stability. The study found that serum samples from acute phase reaction patients showed significant differences in ACA compared with healthy individuals, with a p value of 0.018; serum samples from patients with nephrotic syndrome showed significant differences in AC, ACA, and ACA/AC compared with healthy individuals, with p values of 0.014, 0.002, and 0.041, respectively. Erythrocyte fragments have dissociation-agglutination effect. The complement system immunological functional detection method, based on this effect, has potential clinical application value due to its sensitivity and accuracy.

Initial investigation on the feasibility of porcine red blood cells from genetically modified pigs as an alternative to human red blood cells for transfusion.

The decline in blood donation rates and the ongoing shortage of blood products pose significant challenges to medical societies. One potential solution is to use porcine red blood cells (pRBCs) from genetically modified pigs as an alternative to human red blood cells (hRBCs). However, adverse immunological reactions remain a significant obstacle to their use. This study aimed to evaluate the compatibility of diverse genetically modified pRBCs with human serum. We acquired human complement-competent serum, complement 7 (C7)-deficient serum, and hRBCs from all ABO blood types. Additionally, we used leftover clinical samples from health checkups for further evaluation. pRBCs were collected from wild-type (WT) and genetically modified pigs: triple knockout (TKO), quadruple KO (QKO), and TKO/hCD55.hCD39 knockin (hCD55.hCD39KI). The extent of C3 deposition on RBCs was measured using flow cytometry after incubation in C7-deficient serum diluted in Ca++-enriched or Ca++-depleted and Mg++-enriched buffers. The binding of immunoglobulin (Ig) M/IgG antibody to RBCs after incubation in ABO-type human serum was evaluated using flow cytometry. Naïve human serum- or sensitized monkey serum-mediated hemolysis was also evaluated. Phagocytosis was assessed by incubating labeled RBCs with the human monocytic cell line THP-1 and measurement by flow cytometry. All three genetic modifications significantly improved the compatibility of pRBCs with human serum relative to that of WT pRBCs. The extent of IgM/IgG binding to genetically modified pRBCs was lower than that of WT pRBCs and similar to that of O-type hRBCs. Total and alternative pathway complement activation in all three genetically modified pRBCs was significantly weaker than that in WT pRBCs and did not differ from that in O-type hRBCs. The extent of serum-mediated hemolysis and phagocytosis of these genetically modified pRBCs was low and similar to that of O-type hRBCs. Sensitized monkey serum-mediated hemolysis in QKO and TKO/hCD55.hCD39KI pRBCs was higher than in O-type hRBCs but lower than in TKO pRBCs. The elimination of porcine carbohydrate antigens in genetically modified pigs significantly enhanced pRBC compatibility with naïve human sera, which was comparable to that of O-type hRBCs. These findings provide valuable insights into the development of pRBCs as potential alternatives to hRBCs.

Alternative Complement Pathway Inhibition by Lampalizumab: Analysis of Data From Chroma and Spectri Phase III Clinical Trials.

Lampalizumab, an antigen-binding fragment of a humanized monoclonal antibody directed against complement factor D (CFD), is designed to treat geographic atrophy (GA) secondary to age-related macular degeneration. Given the lack of clinical efficacy observed in patients with GA in the phase III Chroma/Spectri trials, we investigated the impact of lampalizumab on the complement system invivo. We developed 6 novel assays to measure changes in complement pathway activities in aqueous humor samples collected from patients enrolled in these trials. Chroma/Spectri were double-masked, sham-controlled, 96-week trials. Aqueous humor samples from 97 patients with bilateral GA across all groups (i.e., intravitreous lampalizumab 10 mg every 6 weeks, every 4 weeks, or corresponding sham procedures) were tested. Novel antibody capture assays were developed on the Simoa platform for complement factor B (CFB), the Bb fragment of CFB, intact complement component 3 (C3), processed C3, intact complement component 4 (C4), and processed C4. The ratio of processed vs. intact complement factors (i.e., complement activity) in aqueous humor were assessed. Patients treated with either of the lampalizumab regimens demonstrated an increase in CFD level at week 24 compared with baseline, along with a corresponding median reduction in the Bb:CFB ratio of 41% to 43%. There were no strong correlations between lampalizumab concentrations in aqueous humor and change in CFD levels or Bb:CFB ratio over time. No change in downstream C3 processing was observed with lampalizumab treatment. Additionally, there was no change in C4 processing. The collection of aqueous humor samples from patients in Chroma and Spectri trials provided key insights on the effects of lampalizumab, a novel complement inhibitor, on local ocular complement activation. Lampalizumab inhibited the alternative complement pathway in the eyes of patients with GA; however, this did not translate into a measurable reduction in either classical or total complement activity, based on absence of changes in C4 and C3 processing, respectively. Proprietary or commercial disclosure may be found after the references.

Differential expression of IFN-α, IL-12 and BAFF on renal immune cells and its relevance to disease activity and treatment responsiveness in patients with proliferative lupus nephritis

ObjectiveSince molecularly targeted therapies are emerging for treating lupus nephritis (LN), this study aimed to assess the immunohistochemical findings of the cytokines in renal tissue and their pathological and clinical...

Complement Heat Tolerance as a Marker of Protein Fragility and Its Clinical Significance.

This study aimed to establish a complement tolerance test (CTT) as a marker of protein fragility and discuss its clinical significance. Total complement activity (TCA) of serum was measured using a self-hemolysis colorimetric method. Human O-erythrocytes and rabbit anti-human O-erythrocyte antibodies were used to replace sheep erythrocytes and the corresponding hemolysin for the hemolysis test, respectively. The antigen-antibody specific binding activated the classical pathway of complement, generating a membrane attack complex, and the red blood cells rupture. A CTT was established to measure complement heat tolerance according to the sensitivity of complement proteins to temperature, which was calculated according to differences in TCA at different temperatures. The smaller the CTT the stronger the complement resistance to heat. The method was applied to the detection of diabetic patients and healthy controls. The mean value of CTT (mean) = 0.063 ± 0.003 with a coefficient of variation of 4.8% for the same specimen tested for complementary thermal resistance on 5 consecutive days, which is a good stability of the assay. Application of CTT on samples from patients with different ages revealed significantly higher mean CTT values for elderly patients (≥60-years old) relative to those for younger patients (20-40-years old) (p < 0.05). In addition, the mean CTT values for diabetic patients were significantly higher than those for healthy patients (p < 0.001). We successfully established a method that uses complement thermal resistance as a marker of protein fragility, with the results demonstrating the ability of the CTT identify age- and disease-related variations in patient samples and its potential efficacy for clinical application.

Complement as a Biomarker for Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a disease of immune complex deposition; therefore, complement plays a vital role in the pathogenesis of SLE. In general, complement levels in blood and complement deposition in histological tests are used for the management of SLE. Thus, the evaluation of complement status can be useful in the diagnosis of SLE, assessment of disease activity, and prediction of treatment response and prognosis. In addition, novel complement biomarkers, such as split products and cell-bound complement activation products, are considered to be more sensitive than traditional complement markers, such as serum C3 and C4 levels and total complement activity (CH50), which become more widely used. In this review, we report the complement testing in the management of SLE over the last decade and summarize their utility.

Associations between serum levels of C3, C4, and total classical complement activity in COVID-19 patients at the time of admission and clinical outcome

In the present study, we investigated the association between complement system status at the time of admission and clinical outcomes in COVID-19 patients. This single-center study was carried out with sixty-one adult patients with COVID-19 who were hospitalized at Imam Hassan Hospital of North Khorasan University of Medical Sciences (Bojnurd, Iran) with less than three days passage since onset of COVID-19 symptoms. Twenty-three healthy volunteers with demographic features similar to the patient group (matched by age and gender) were included in the study as a control group. Patient information including demographic information, demographic data, clinical characteristics, and clinical outcomes were obtained from electronic medical records. Of 61 hospitalized patients with COVID-19, 28 (47.54%) were female, and the average age was 48.78.8 years. The healthy control group included 23 cases (11 (47.8%) female, 12 (52.1%) males, mean age 46.44.4 years). Twenty-one of the 61 patients (34.4%) were admitted to the ICU, and sixteen of them (26.2%) died. Thirty-three (54.10%) patients with COVID-19 were hospitalized for less than 7 days, and 28 (45.90%) of them were hospitalized for 7 days. Our results show that length of hospital stay in the no-ICU group was significantly lower than the ICU admission or death groups (6.490.24 vs. 8.851.59 and 10.531.80, p = 0.0002). The levels of C3, C4, and CH50 were determined through the immunoturbidimetric method and single-radial-haemolysis plates, respectively, on serum samples obtained from patients at the time of admission or those in the control group. Our results indicate that C3, C4 and CH50 levels were markedly lower in COVID-19 patients than in the control group. We also found that complement parameter levels in COVID-19 patients who died or were admitted to ICU were significantly lower than in non-ICU COVID-19 patients. In general, it seems that serum level of C3, C4, and CH50 at admission may predict disease progression or adverse clinical outcome in COVID-19 patients.

Measurement of Complement Activation via Plasma-Soluble C5b-9 Comparison with Terminal Complement Complex Staining in a Series of Kidney Biopsies

Introduction: With the emergence of therapeutic complement inhibitors, there is a need to identify patients with complement-driven inflammation. C5b-9 is the terminal product of the three complement pathways and therefore a marker of total complement activation. We present a pilot study which aims to assess whether plasma soluble C5b-9 (sC5b-9) correlates with terminal complement complex (TCC) staining in kidney tissue. The secondary aim was to assess the utility of plasma sC5b-9 as part of routine workup in kidney patients undergoing kidney biopsy. Methods: Thirty-seven patients undergoing kidney biopsy had plasma sC5b-9 and TCC staining on kidney tissue performed. Additional blood markers including creatinine, haemoglobin, CRP, factor H, factor I, and midkine levels were also taken. These parameters were correlated with the histological diagnoses. Patients were divided into a diseased group (n = 31) and a control group (n = 6) consisting of transplanted kidneys with minor or no changes. Of the biopsies in the control group, 50% were performed as per protocol, and the other 50% were performed due to clinical need. Results: There was no correlation found between plasma sC5b-9 and TCC kidney staining. Elevated sC5b-9 levels were found in a heterogeneous group of patients but were associated with higher CRP and lower haemoglobin levels. Overall, there was more TCC kidney staining in the diseased group compared with the control group, and a trend was observed of diabetic, primary membranous nephropathy, and amyloidosis patients having more intense glomerular and peritubular/interstitial staining. Conclusion: Plasma sC5b-9 as a marker of total complement activation does not correlate with TCC kidney staining. This discordance suggests that plasma sC5b-9 and TCC staining are distinct markers of disease. TCC staining reflects chronicity and tissue deposition of complement over time. Conversely, plasma sC5b-9 concentrations change rapidly and reflect systemic complement activation. Complement activation was present in a heterogeneous group of kidney disease, indicating the underlying role of complement in many disorders.

Profile of antiphospholipid antibodies and complement system in COVID-19 patients of different severity

COVID-19, a severe acute respiratory syndrome caused by SARS-CoV-2, may predispose to thrombotic events, especially when combined with antiphospholipid antibodies (aPL). However, there are limited data on prevalence and antigenic specificity of aPL in COVID-19. Complement activation is assumed to play an important role in pathogenesis of COVID-19-associated coagulopathy. During the SARS-CoV-2 pandemic, it is necessary to identify important biomarkers for predicting severe course of COVID-19 and risk of thrombotic complications. Our objective was to evaluate the aPL profile, quantitative content and activity of complement and its components in COVID-19 patients graded by severity in the course of time. IgM and IgG antibodies to cardiolipin (CL), phosphatidylserine (PS), β2-glycoprotein-I (β2-GP-I), prothrombin (PT), annexin V (An V), as well as C1q complement component, content of its C3 and C4 components and total complement activity were determined in blood serum using ELISA approach. 141 patients with COVID-19 were included in the study. Group 1 consisted of 39 patients with mild form, group 2 (65 patients) presented with moderate form, and group 3 included 37 patients with severe form of COVID-19. Blood samples were obtained on day 3-7 of the disease (1st point) and after 14-28 days (2nd point). The results were as follows: aPL were detected in 29.1% of the total COVID-19 cohort, frequency of aPL detection by the severity grade did not differ (33.3%, 24.6% and 32.4%). In 8.5% of the patients, aPL were detected only at the 1st time point; in 14.2%, only at the 2nd point; and in 6.4% of the cases, at the both time points. Antibodies to PT (16.3%) and An V (11.3%) were revealed more frequently. The detection frequency of antibodies to PT was significantly higher than antibodies to CL and PS (7.1%), β2-GP-I (7.8%). The prevalence of aPL in groups 1 and 3 did not differ. At the 1st point in group 3, increased levels of C4 (89.2%) and C3 (24.3%) in blood, and a decrease in complement activity (35.1%) were more often observed than in group 1. At the 2nd time point in group 3, a decrease in complement activity was often detected (59.5%). The C3 levels exceeding 720 μg/ml were found to predict a 2.6-fold increased risk of severe COVID-19, and this risk became 3.3 times higher at C4 levels of &gt; 740 μg/ml. The antibodies to PT and An V are often detected in COVID-19 patients, along with low prevalence of antibodies to CL and β2-GP-I. These antibodies can be involved in pathogenesis of COVID-19-associated coagulopathy, being detectable at the late stage of the disease, and they may trigger APS in predisposed patients and reconvalescents. Although presence of aPL antibodies is not associated with COVID-19 severity, their persistence over the period of convalescence may be an additional risk factor for thromboembolic complications. The COVID-19 patients are characterized by activation of the complement system, which increases in severe cases, and manifests with increased or decreased levels of C3 complement component, increased levels of C4 component in blood, and a decreased total complement activity. Quantitative determination of C3 and C4 complement components over the period of COVID-19 progression is of prognostic value, with respect to severity of the disease.

A Flow Cytometry-Based Assay for the Measurement of Total Complement Activity in the Serum and Clinical Practice.

Objective To develop a novel sensitive and accurate assay suitable for high-volume testing of the total complement activity in the serum for clinical laboratories. Methods The total complement activity (TCA) to be measured was quantified by detecting the number of fragments produced by erythrocyte lysis and the erythrocyte fragmentation index (EFI), indicating TCA. EFI = M × M2/(M1 + M2), where M is the number of erythrocyte fragments (removed from the background), M1 is the number of unagglutinated red cells, M2 is the number of agglutinated red cell groups, and M2/(M1 + M2) is the agglutination coefficient indicating the degree of erythrocyte agglutination. Mild changes in hemolysin and erythrocyte concentrations were made to optimize the testing conditions. The same serum samples were tested for 10 consecutive days to determine the stability of the experimental results. Serum EFI was detected in both nephrotic syndrome patients and healthy subjects. Results There was a linear relationship between hemolysin and erythrocyte agglutination (r = 0.999, P < 0.001). A good linear relationship existed between EFI and TCA (r = 0.991, P < 0.001). The results were not affected by slight fluctuations in the concentrations of hemolysin or erythrocytes. The interbatch CV = 8.6% of the test results showed good stability. There was a significant difference in the EFI between nephrotic syndrome patients and healthy individuals, P < 0.001, and EFI was reduced in nephrotic syndrome patients compared to healthy individuals. Conclusion The flow cytometry-based assay for TCA was sensitive and accurate and had potential value for clinical application.

Complement system component dysregulation is a distinctive feature of COVID-19 disease: a prospective and comparative analysis of patients admitted to the emergency department for suspected COVID-19 disease

The complement system (CS) plays a pivotal role in Coronavirus disease 2019 (COVID-19) pathophysiology. The objective of this study was to provide a comparative, prospective data analysis of CS components in an all-comers cohort and COVID-19 patients. Patients with suspected COVID-19 infection admitted to the Emergency department were grouped for definite diagnosis of COVID-19 and no COVID-19 accordingly. Clinical presentation, routine laboratory and von Willebrand factor (vWF) antigen as well as CS components 3, 4 and activated 5 (C5a) were assessed. Also, total complement activity via the classical pathway (CH50) was determined. Levels of calprotectin in serum were measured using an automated quantitative lateral flow assay. We included 80 patients in this prospective trial. Of those 19 (23.7%) were tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients with COVID-19 had higher levels of CS components 5a and 4 (54.79 [24.14–88.79] ng/ml vs. 35 [23.15–46.1] ng/ml; p = 0.0433 and 0.3772 [± 0.1056] g/L vs. 0.286 [0.2375–0.3748] g/L; p = 0.0168). COVID-19 patients had significantly higher levels of vWF antigen when compared to the control group (288.3 [± 80.26] % vs. 212 [151–320] %; p = 0.0469). There was a significant correlation between CS C3 and 5a with vWF antigen (rs = 0.5957 [p = 0.0131] and rs = 0.5015 [p = 0.042]) in COVID-19 patients. There was no difference in calprotectin plasma levels (4.786 [± 2.397] µg/ml vs. 4.233 [± 2.142] µg/ml; p = 0.4175) between both groups. This prospective data from a single centre all-comers cohort accentuates altered levels of CS components as a distinct feature of COVID-19 disease. Deregulation of CS component 3 and C5a are associated with increased vWF antigen possibly linking vascular damage to alternative CS activation in COVID-19.

Whole Genome Sequencing Identifies a Recurrent Mutation in Complement Factor I (CFI) in Primary Myelofibrosis (PMF)

Whole Genome Sequencing Identifies a Recurrent Mutation in Complement Factor I (CFI) in Primary Myelofibrosis (PMF)

Physiological and transcriptional analysis of Chinese soft-shelled turtle (Pelodiscus sinensis) in response to acute nitrite stress

Nitrite is a harmful substance in aquaculture, and has a serious impact on the survival of the Chinese soft-shelled turtle, Pelodiscus sinensis. However, the cellular responses of P. sinensis to nitrite stress have not yet been investigated. The present study showed that nitrite led to a decrease in hemoglobin content and an increase in methemoglobin content in the blood, thus reducing the oxygen-carrying capacity of blood in P. sinensis. Nitrite also affects the antioxidant system of the liver and leads to lipid peroxidation. In addition, nitrite caused immune responses, including a decrease in lysozyme content and an increase in total complement activity, interleukin-6, and heme oxygenase concentrations in the serum. Additionally, the terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay showed that apoptosis occurred in liver cells. Finally, a comparative transcriptome analysis was conducted. A total of 573 differentially expressed genes and 15 significantly enriched KEGG pathways were identified. Among them, the glutathione S-transferase omega 1 (GSTO1) gene may relieve nitrite-induced oxidative damage in P. sinensis by participating in a variety of redox-related pathways, while the PPAR signaling pathway has been proposed to play an important regulatory role in lipid metabolism and immune responses. The present study comprehensively explored the cellular responses of P. sinensis to nitrite stress and provided guidance for future studies.

Pathophysiology of streptokinase-induced hypotension in acute myocardial infarction: a systematic review of clinical evidence.

IntroductionDespite the common occurrence of streptokinase-induced hypotension among patients with acute myocardial infarction, the underlying pathophysiology remains obscure and poorly understood. Our study aimed to pool clinical evidence on the potential mechanism of streptokinase-induced hypotension through a systematic review of the literature.Material and methodsWe conducted literature search from Medline, Scopus and Web of Science on clinical studies related to streptokinase-induced hypotension.ResultsOur search yielded 972 citations. After removal of duplicates, 878 articles were screened for eligibility, of which 856 papers were excluded due to various reasons. Of the remaining 22 articles retrieved with full texts, eight relevant articles were selected for final analysis. Three themes emerged as the proposed mechanisms of streptokinase-induced hypotension, including (i) reduction in total peripheral resistance, (ii) complement activation, and (iii) dismissal of hypotheses involving other intermediaries.ConclusionsOur findings suggest that the underlying mechanism of streptokinase-induced hypotension lies primarily in the reduction in total peripheral resistance.

Effects of dietary marjoram, Origanum majorana extract on growth performance, hematological, antioxidant, humoral and mucosal immune responses, and resistance of common carp, Cyprinus carpio against Aeromonas hydrophila

The present study aimed to investigate the potential effects of dietary marjoram extract on growth performance, health, and disease resistance in common carp, Cyprinus carpio. To this purpose, the fish were assigned into four treatments and fed by diets supplemented with 0 (control), 100, 200, and 400 mg marjoram extract kg−1 over eight weeks and then challenged with Aeromonas hydrophila. According to the results, 200 mg kg−1 dietary marjoram extract inclusion showed the highest final weight, weight gain, and specific growth rate, and lowest feed conversion ratio (FCR). White blood cell number, Red blood cells, hematocrit, hemoglobin, mean corpuscular volume and mean corpuscular hemoglobin were markedly increased particularly at 200 mg kg−1 treatment. Marjoram extract significantly increased plasma superoxide dismutase activity and decreased malondialdehyde level compared to the control treatment. Plasma complement and lysozyme activities and total immunoglobulin levels, mucosal complement, lysozyme and alkaline phosphatase activities and immunoglobulin levels were significantly increased compared to the control group. The lowest post-challenge survival rate was observed in the control treatment, whereas the highest value was related to the 200 mg kg−1 marjoram treatment. In conclusion, the present study demonstrated that, marjoram extract is a suitable feed supplements for common carp, as it stimulates the fish growth, antioxidant, and immune systems, which suppress the fish mortality during Aeromonas septicemia. According to the results, 200 mg marjoram extract kg−1 is recommended for carp feed formulation.

Bacterial infections in a pediatric cohort of primary and acquired complement deficiencies

BackgroundAcquired complement deficiency can occur in the setting of autoimmune syndromes, such as systemic lupus erythematosus (SLE), with very low or, occasionally, undetectable C3 levels. Based on inherited complement defects, patients with transiently low complement may be at similar risk for serious bacterial infection, but the degree of risk related to C3 level and temporal association is unknown.MethodsWe performed a retrospective study including pediatric patients with undetectable total complement activity or absent individual complement components measured at our institution from 2002 to 2018. We assessed annual rate of serious bacterial infection (SBI) defined as requiring hospitalization and/or parenteral antibiotics by manual chart review. Among included SLE patients, we assessed the 30-day probability of SBI for given C3 measurements using a logistic regression model to determine risk. Primary complement deficiency was analyzed for SBI rate as comparison. Covariates included age, level of immune suppression and history of lupus nephritis.ResultsAcquired complement deficiency secondary to SLE-related disease [n = 44] was the most common underlying diagnosis associated with depressed complement levels and were compared to a cohort of primary complement deficient patients [n = 18]. SBI per 100 person-years and cohort demographics were described in parallel. Our logistic regression analysis of pediatric patients with SLE showed low C3 level was temporally associated with having an SBI event. Given equivalent immunosuppression, patients with an SBI had lower C3 levels at the beginning of the observation period relative to patients without SBI.ConclusionPediatric patients with the diagnosis of SLE can develop very low C3 levels that associate with risk of serious bacterial infection comparable to that of patients with primary complement deficiency. Patients prone to severe complement consumption may particularly be at risk.