Complement C3 Research Articles

B-098 Clinical comparison of five assays for the detection of anti-dsdna antibodies and their correlation with complement consumption

Abstract Background Anti-dsDNA antibodies are highly specific and part of the classification criteria for systemic lupus erythematosus (SLE). They correlate with disease activity and contribute to the pathogenesis of lupus nephritis (LN). This study aimed to compare five methods for anti-dsDNA antibody detection and to estimate their association with complement consumption. Methods 186 samples were collected at Labcorp and tested on five assays: Crithidia luciliae indirect immunofluorescence test (CLIFT, Euroimmun, Lübeck Germany), BioPlex 2200 dsDNA (BioRad, Hercules, US), QUANTA Lite HA dsDNA ELISA, QUANTA Flash dsDNA chemiluminescent immunoassay (CIA), and Aptiva dsDNA, a particle-based multi-analyte technology (PMAT) immunoassay (all 3 assays, Inova Diagnostics, USA). Complement C3 and C4, measured with Cobas c 502 (Roche Diagnostics, USA), were used as serological surrogates and compared to each assay to assess the correlation with disease activity. Results The quantitative agreement varied between 0.60 (BioPlex vs. CLIFT) and 0.96 (Aptiva vs. QUANTA Flash) (Table 1). The C3 agreement from highest to lowest was: HA dsDNA ELISA, CLIFT, QUANTA Flash, Aptiva, then BioPlex 2200. The findings were compared to qualitative results derived from CLIFT testing, since CLIFT is often used as the confirmation assay for anti-dsDNA. The highest area under the curve (AUC) from the receiver operating characteristic (ROC) curve was found for QUANTA Flash (0.95) followed by Aptiva and HA ELISA (both 0.94) and then BioPlex (0.87). Conclusions Anti-dsDNA antibodies measured using different methods showed varying agreement with CLIFT and complement consumption. Aptiva and QUANTA Flash dsDNA were highly correlated and in strong concordance with low C3 levels.

A-128 Evaluation of the Analytical Performance of Three Inflammation Related Assays on the Atellica CI Analyzer

Abstract Background The Atellica® CI Analyzer is an automated, high-throughput integrated chemistry and immunoassay analyzer utilizing both Atellica® CH and Atellica® IM Assays. This study evaluated the analytical performance of the the Atellica CH Complement C3 (C3), Complement C4 (C4), and Alpha-1-acid Glycoprotein (AAG) Assays on the Atellica CI Analyzer. Methods Precision studies were performed according to CLSI EP05-A3 using native and contrived human serum samples. One aliquot of each sample was tested in duplicate in two runs per day ≥2 hours apart on each analyzer for ≥20 days. Precision was evaluated using three reagent lots on one system. Method comparison (MC) studies were performed using three reagent lots according to CLSI EP09c. Individual native and contrived human serum samples were analyzed using the Atellica CH C3, C4, and AAG Assays on the Atellica CH Analyzer and the Atellica CI Analyzer. LoB and LoD were determined as described in CLSI EP17-A2. Results Representative precision and MC results for each assay are listed in the table. For the three assays tested, repeatability and within-lab %CVs were <1.4% and <3.3%, respectively. Slopes determined by the Deming linear regression model were approximately equal to 1. Detection capability for the Atellica CH C3 Assay on the Atellica CI Analyzer was estimated at 0.2 mg/dL (0.00 g/L) and 0.4 mg/dL (0.00 g/L) for LoB, and LoD. For the Atellica CH C4 Assay, LoB and LoD were determined at 0.1 mg/dL (0.00 g/L) and 0.2 mg/dL (0.00 g/L). For the Atellica CH AAG Assay, LoB and LoD were determined at 0.9 mg/dL (0.01 g/L) and 2.0 mg/dL (0.02 g/L). Conclusions Evaluation of the Atellica CH C3, C4, and AAG Assays using the Atellica CI Analyzer demonstrated good precision and equivalent performance compared to the same assays on the Atellica CH Analyzer.

Recurrence of Atypical Hemolytic Uremic Syndrome (HUS) after Kidney Transplantation in Patients with the Complement C3 p.Arg161Trp Variant

Recurrence of Atypical Hemolytic Uremic Syndrome (HUS) after Kidney Transplantation in Patients with the Complement C3 p.Arg161Trp Variant

ACE in Neutrophils Ameliorates Glomerular Damage in Immune Complex-Mediated Crescentic Glomerulonephritis via Complement C3 and C and N Domains of ACE

ACE in Neutrophils Ameliorates Glomerular Damage in Immune Complex-Mediated Crescentic Glomerulonephritis via Complement C3 and C and N Domains of ACE

Glomerular Injury and Differences in Colocalization of Glomerular IgA, IgG, and Complement C3 in Patients with IgA Vasculitis with Nephritis

Glomerular Injury and Differences in Colocalization of Glomerular IgA, IgG, and Complement C3 in Patients with IgA Vasculitis with Nephritis

High expression of CD3+T-lymphocytes in cerebrospinal fluid increases the risk of critical cerebral hemorrhage with systemic inflammatory response syndrome (SIRS) after surgery

ObjectiveTo assess the frequency of lymphocyte subsets and other laboratory indicators in paired cerebrospinal fluid (CSF) and peripheral blood (PB) samples from critically ill patients with intracerebral hemorrhage (ICH) who developed systemic inflammatory response syndrome (SIRS) following surgery. IntroductionNeuroinflammation and systemic inflammatory responses significantly contribute to secondary brain injury following ICH. Post-surgery SIRS is known to worsen clinical outcomes in ICH patients; however, the immune response in the CSF and PB has not been fully characterized. Understanding immunological changes in ICH patients with SIRS could lead to improved clinical management and prognostic outcomes. MethodsThis study involved a retrospective analysis of data from patients with ICH who underwent surgery in the Neurological Intensive Care Unit (NICU) of Baoding No. 1 Hospital, Hebei Province, China, between January and July 2022. Patients were divided into SIRS and non-SIRS groups based on the clinical criteria. Demographic, clinical, and laboratory data, including lymphocyte subsets in CSF and PB, were collected and analyzed. This study compared lymphocyte subsets and other inflammatory markers between the SIRS and non-SIRS groups. ResultsPatients with SIRS demonstrated higher systolic blood pressure (SBP) at admission, worse 90-day prognoses, elevated inflammatory markers, increased levels of complement proteins C3 and C4, and lower levels of immunoglobulin G (IgG) compared to patients without SIRS. Between 3–6 days post-surgery, SIRS patients showed higher percentages of CD3+T cells, CD4+T cells, and CD4+/CD8+ ratios in the CSF than non-SIRS patients. CD3+T cell percentages in the CSF were consistently higher than those in the PB and were independent of PB levels. In contrast, CD3-CD16+CD56+ natural killer (NK) cell percentages were lower in patients with SIRS. No significant differences in PB lymphocyte subsets were found between the two groups. A high CSF CD3+T cell percentage (≥85.68 %) was identified as the strongest predictor of critical ICH with SIRS after surgery, with an appropriate use criterion (AUC) of 0.7742, sensitivity of 77.42 %, specificity of 76.19 %, and 95 % CI of 0.6655–0.8829 (P < 0.0001). ConclusionElevated levels of CD3+T lymphocytes in CSF are strongly associated with an increased risk of severe cerebral hemorrhage and SIRS following surgery. These findings suggest that monitoring CSF immune markers, particularly CD3+T lymphocytes, could serve as valuable predictors for the development of SIRS in critically ill ICH patients and inform post-surgical treatment strategies.

Type 2 Diabetes Mellitus Aggravates Complement Dysregulation and Affects Cortisol Response in Patients with Post-COVID-19.

COVID-19 viral infection results in dysregulation of the complement system and a decrease in cortisol and adrenocorticotropin hormone (ACTH) levels. This study aimed to explore the complement system, as well as cortisol and ACTH responses in patients with post-COVID-19 conditions (PCC) and type 2 diabetes mellitus (T2DM). This study recruited 31 patients with PCC and T2DM (PCC-T2DM), 19 patients with PCC (PCC), 10 patients with T2DM (T2DM), and 10healthy participants (control). Cortisol and ACTH in the PCC and PCC-T2DM groups were assessed using the insulin tolerance test. In the fasting state, serum samples were collected for proteomic analyses. Spearman correlation analysis was performed between proteins and cortisol, as well as between proteins and ACTH. Cortisol and ACTH levels were consistently decreased in the PCC and PCC-T2DM groups. Proteomic analyses revealed that most of the differentially abundant proteins (DAPs) in the PCC vs control and PCC-T2DM vs T2DM were involved in the coagulation and complement cascade, and the essential complement C3 was significantly upregulated in the PCC and PCC-T2DM groups when compared to their controls. Additionally, complement-related DAPs in the PCC vs control and PCC-T2DM vs T2DM were significantly correlated with cortisol and ACTH levels. In comparing PCC-T2DM samples with PCC samples, we found that upregulated DAPs were linked to the complement system and other immune system, and most DAPs were negatively correlated with cortisol and ACTH. Our study revealed that T2DM exacerbated dysregulation of the complement system in patients with PCC, and significant correlations were present between complement protein levels and those of cortisol and ACTH. These results provide novel insights into the dysregulation of complement and endocrine hormones in patients with PCC and T2DM.

Urinary Complement C3 and Vitamin D-Binding Protein Predict Adverse Outcomes in Patients with Acute Kidney Injury after Cardiac Surgery

Introduction: Acute kidney injury (AKI) is associated with adverse outcomes, including death and dialysis. The goal of this study was to identify prognostic biomarkers of AKI that could be used across multiple phenotypes of AKI and across different species. Methods: Liquid chromatography/tandem mass spectrometry analysis of urine samples from three species (human, rat, and mouse) and four etiologies of AKI identified five potential biomarkers, of which two were validated, complement C3 and vitamin D-binding protein, in a cohort of 157 patients that developed AKI following cardiothoracic surgery. We studied the relationship between the biomarker’s concentration in the urine and the development of a composite primary endpoint (stage 3 AKI within 10 days or death within 30 days). Results: Of the 153 patients who developed AKI following cardiovascular surgery, 17 met the combined primary outcome. The median concentration of urine complement C3 adjusted to urine creatinine had the best predictive value and was significantly higher in the primary outcome group than in the controls. Similarly, the median concentration of vitamin D-binding protein was higher in the primary outcome group. Conclusions: The studies provide proof in principle that cross-species discovery analyses could be a valuable tool for identifying novel prognostic biomarkers in AKI. Urine complement C3 and vitamin D-binding protein could be promising early predictors of adverse outcomes in patients who develop AKI after cardiac surgery.

Effect of the injection of protoscolex antigens for hydatid cysts on some immunological parameters and the protection of injury

This study aimed to that capability of preparation of antigens from protoscolex found inside the hydatid cyst and likewise possibility of preparing antigen providing protection of the injury of this cysts. Cystic echinococcosis is the more important parasitic disease caused by a cestode tapeworm of species Echinococcus granulosus, spreading a lot in Iraq and the Eastern Mediterranean Countries in addition to its world distribution. The protoscolex found inside hydatid cysts results from the germinal layer of hydatid cyst isolated from people by the surgery section at the Fallujah teaching hospital to find out the extent of its influence on both of the cellular and humeral immunity. 20 white mice (Balb/c) were divided into two groups, the first group of white mice (Balb/ c) was injected subcutaneously with a concentration of 0.1ml of antigen and it measured antibodies IgG, IgA, IgM, IgE as well as injected with complement C3, C4 and the insulation of neutrophil cells and measuring percentage of phagocytosis, reduction of a dye NBT and viability of neutrophil cells and in the second group, the protoscolex was injected in the liver with a concentration 0.1ml to find out the extent of prevention provided by the antigen to prevent or to reduce injury. The results showed a significant increase for all types of antibodies and complements C3 , C4 and reduction of a dye NBT and phagocytosis especially at the time 60 minute and the results were not showing significant differences on viability of neutrophil cells. As for prevention of injury, the results have shown a significant difference at the level &lt; 0.05 and reached the percentage of prevention 56.4 % compared to the subordinate control. The results showed small size of the hydatid cyst in the experience parameters compared to the subordinate control.

Iptacopan (Fabhalta) for Paroxysmal Nocturnal Hemoglobinuria

The FDA has approved the complement factor B inhibitor iptacopan (Fabhalta – Novartis) for treatment of paroxysmal nocturnal hemoglobinuria (PNH) in adults. Iptacopan is the first oral drug to be approved in the US for this indication. Three parenterally administered drugs, the complement C5 inhibitors eculizumab (Soliris) and ravulizumab (Ultomiris) and the complement C3 inhibitor pegcetacoplan (Empaveli), are also approved for treatment of PNH.

Noninvasive diagnostic value of urinary mir-663a in pediatric lupus nephritis

Abstract Background and objectives Lupus nephritis (LN) is a severe clinical manifestation seen in individuals with systemic lupus erythematous (SLE). It has a poor long-term prognosis in pediatric patients with high morbidity and mortality rates. MicroRNAs (miRNAs) are noncoding small RNAs that act as epigenetic modulators, regulating gene expression, and modulating the understanding of mechanisms and pathogenesis of human diseases. Depending on bioinformatics analysis, we aimed to investigate urinary expression of miR-663a in LN among SLE children and discriminate between proteinuria of LN versus chronic renal disease without SLE. Methods The urinary miR-663a expression levels were estimated in cellular pellets from 15 SLE patients, 15 SLE and biopsy-proven active LN patients, 15 chronic kidney disease (CKD) patients rather than LN and 15 healthy controls. Results LN patients had significantly higher urinary miR-663a expression levels compared to other groups (p &lt; 0.0001). Urinary miR-663a at a cutoff of 8.61 had a diagnostic value of 93.3% for LN among pediatric SLE with 100% specificity (p &lt; 0.0001). Moreover, miR-663a was upregulated in advanced grades and LN classes V, IV, and III compared to class II. Furthermore, miR-663a was positively correlated with the duration of SLE, activity index, chronicity index, urinary protein, anti-dsDNA, and SLEDAI score, and negatively correlated with serum complement C3 (p &lt; 0.05). Conclusion miR-663a could be related to the pathogenesis of kidney damage in LN; that could provide a specific noninvasive diagnostic and follow -up tool for LN patients.

Low Levels of Complement Factor H in the First Trimester of Pregnancy Are Associated with Spontaneous Preterm Birth.

Preterm birth (PTB) remains a significant public health concern, and prediction is an important objective, particularly in the early stages of pregnancy. Many studies have relied on cervical characteristics in the mid-trimester, with limited results. It is therefore crucial to identify novel biomarkers to enhance the ability to identify women at risk. The complement pathway is implicated in the process of placentation, and recent proteomics studies have highlighted the potential roles of some complement proteins in the pathophysiology of PTB. To determine the association between the occurrence of spontaneous preterm birth (sPTB) and the concentration of complement C3, factor B, and factor H in the blood of pregnant women during the first trimester. This prospective cohort study included women with singleton pregnancies, both with and without a history of sPTB, from two health institutions in Bucaramanga, Colombia. The outcome was sPTB before 37 weeks. A blood sample was obtained between 11 + 0 to 13 + 6 weeks. ELISA immunoassay was performed to quantify the levels of C3, factor B, and factor H. A total of 355 patients were analyzed, with a rate of sPTB of 7.6% (27/355). The median plasma concentration for C3, factor B, and factor H were 488.3 μg/mL, 352.6 μg/mL, and 413.2 μg/mL, respectively. The median concentration of factor H was found to be significantly lower in patients who delivered preterm compared to patients who delivered at term (382 μg/mL vs. 415 μg/mL; p = 0.034). This study identified a significant association between low first-trimester levels of factor H and sPTB before 37 weeks. These results provide relevant information about a new possible early biomarker for sPTB. However, the results must be confirmed in different settings, and the predictive value must be examined.

Mediating role of inflammatory indicators in the association between sleep status and blood pressure in centenarians: evidence from China Hainan Centenarian Cohort Study.

To conduct a comprehensive analysis in Hainan centenarians on the link between sleep status and their blood pressure status. Furthermore, the study also aims to explore how inflammatory indicators may mediate the relationship. The China Hainan Centenarians Cohort Study (CHCCS) collected baseline data on sleep status, inflammatory indicators, and blood pressure data. The study used a mediation model to investigate how inflammatory indicators mediate the relationship between sleep status and blood pressure status. In this study, a total of 967 centenarians were included. The prevalence of hypertension among the centenarians was 71.4%. The analysis showed that centenarians with poor sleep quality had a 43% higher risk of hypertension compared to those with normal sleep quality (OR = 1.43, 95% CI: 1.03-1.97). Additionally, centenarians with nighttime sleep durations of ≤ 6 h or > 9 h had higher proportions of high pulse pressure (PP), with OR values of 1.76 (95% CI: 1.18-2.63) and 2.07 (95% CI: 1.34-3.19), respectively. Mediation analysis illustrated that complement C3 played a mediating role in the relationship between sleep quality and hypertension, with an effect ratio of 2.4%. Similarly, lymphocyte count, the neutrophil-to-lymphocyte ratio (NLR), and the systemic immune-inflammation index (SII) were identified as mediating factors in the association between nighttime sleep duration and high PP, with effect ratios of 91.22%, 36.93%, and 0.20%, respectively. In centenarians, poor sleep quality raises the risk of hypertension, with complement C3 as a mediator. Additionally, nighttime sleep durations of ≤ 6 h or > 9 h increases the risk of high PP, mediated by lymphocyte count, NLR, and SII.

Assessment of immune status markers during occupational lead exposure

The immune system is sensitive to the effects of environmental factors, and according to numerous studies, lead has an immunotoxic effect. At the same time, there is evidence of the multidirectional nature of the impact of lead on the immune system, determined by the degree of exposure to this heavy metal, which makes it current to study changes in immunological markers in workers of a modern lead recycling plant, taking into account levels and complexity of exposure. In the era of personalized medicine, monitoring the potential influence of occupational factors exposure on the immune system can facilitate a personalized approach to the prevention of work-related health conditions. The aim of the study: to evaluate changes in immune status markers among employees of lead recycling plant. The main group – 62 men working at a lead recycling plant, the control group – 47 men not exposed to occupational factors. Laboratory examination included a determination of the lead blood level, a clinical blood test, the serum levels of IL- 1â, IL- 10, IL- 8, MCP-1, C3 and C4 complement components, IgA, IgM, IgG. In the main group, compared to the control group, a higher number of neutrophils, lymphocytes, monocytes, higher levels of IL-8, C3 and C4 components of the complement system, and lower levels of IgM were detected. In the main group, the following changes in markers were significantly more often detected in comparison with reference values: an increase in the C3 component of complement (51.6% in the main group compared to 12.5% in the control group), decreased IgG (24.2% compared to 6.2%) and increased IgA (22.6% compared to 6.2%). Associations were identified between the lead blood level and the number of lymphocytes, the level of IgG, between work experience in contact with lead and the level of MCP-1 and C3 complement components. The results of the studies revealed the presence of changes in the immune status markers of workers at a lead recycling plant, which demonstrate a proinflammatory effect of lead and an influence on the humoral immune status. The identified changes in immunological parameters may underlie the mechanisms of formation of pathological conditions associated with lead exposure, which determines the relevance of continuing research to assess dynamic changes in immunological parameters and develop a system for monitoring the immune status of workers exposed to lead and its compounds to optimize preventive measures.

Pleuropulmonary Manifestations in Patients with Systemic Lupus Erythematosus

Objective — to assess the prevalence of non-infectious pleuropulmonary manifestations in patients with systemic lupus erythematosus (SLE), as well as the demographic, clinical and laboratory characteristics of such patients. Materials and methods. A total of 435 patients with SLE (87.5 % female; median age 37 (26—49) years) were enrolled in a cross-sectional study, including 200 with pleuropulmonary manifestations and 235 without them. Patients were evaluated for demographic details, clinical SLE manifestations, SLE Disease Activity Index 2000 (SLEDAI-2K), SLICC/ACR Damage Index (DI). Laboratory evaluations included complete blood count with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), high-sensitivity CRP (hs-CRP), interleukin-6 (IL-6), IL-10, complement C3 and C4 levels, specific autoantibodies. Procalcitonin and presepsin serum levels were measured to exclude infections. Results and discussion. At least one pleuropulmonary manifestation occurred in 46 % of patients, with pleurisy being the most frequent (24 %). Respiratory involvement was associated with male sex, longer disease duration, and older age at disease onset. Patients with respiratory complications had higher SLEDAI-2K and SLICC/ACR DI scores than those without pleuropulmonary involvement. Patients with pleuropulmonary manifestations more frequently exhibited lymphadenopathy, nephritis, pericarditis, other cardiac manifestations, fever, weight loss, anemia, and thrombocytopenia; conversely, cutaneous manifestations occurred less frequently in patients with pleuropulmonary involvement. Patients with respiratory involvement were found to have higher levels of ESR, CRP, hs-CRP, and IL-6. A higher frequency of positive anti-La/SSB, antiphospholipid, and anti-chromatin antibodies was observed in patients with pleuropulmonary manifestations compared to those without them.In multivariate logistic analysis, respiratory involvement was positively associated with older age (odds ratio (OR) 1.03 (95 % confidence interval (CI) 1.01—1.05), p = 0.004), higher SLEDAI-2K (OR 1.05 (95 % CI 1.01— 1.09), p = 0.030) and SLICC/ACR DI scores (OR 11.34 (95 % CI 1.03—1.74), p = 0.027), presence of lymphadenopathy (OR 2.27 (95 % CI 1.33—3.88), p = 0.003), pericarditis (OR 4.40 (95 % CI 2.29—8.46), p &lt; 0.001), other cardiac manifestations (OR 10.1 (95 % CI 5.65—17.9), p &lt; 0.001), and systemic symptoms (OR 2.14 (95 % CI 1.24—3.70), p = 0.007). Cutaneous manifestations were, on the other hand, negatively associated with the occurrence of pleuropulmonary symptoms (OR 0.27 (95 % CI 0.15—0.50), p &lt; 0.001). Conclusions. Pleuropulmonary manifestations are frequent in SLE, particularly pleuritis. Respiratory involvement is associated with male sex, older age, longer disease duration, and occurs mainly in patients with active and severe lupus, often with previous or concomitant major organ involvement other than lungs. Patients with pleuropulmonary involvement have higher levels of inflammatory markers and higher frequency of positive anti-La/SSB, antiphospholipid, and anti-chromatin antibodies.

Microglia mediate memory dysfunction via excitatory synaptic elimination in a fracture surgery mouse model

Cognitive impairment is a common issue among human patients undergoing surgery, yet the neural mechanism causing this impairment remains unidentified. Surgical procedures often lead to glial cell activation and neuronal hypoexcitability, both of which are known to contribute to postoperative cognitive dysfunction (POCD). However, the role of neuron-glia crosstalk in the pathology of POCD is still unclear. Through integrated transcriptomics and proteomics analyses, we found that the complement cascades and microglial phagocytotic signaling pathways are activated in a mouse model of POCD. Following surgery, there is a significant increase in the presence of complement C3, but not C1q, in conjunction with presynaptic elements. This triggers a reduction in excitatory synapses, a decline in excitatory synaptic transmission, and subsequent memory deficits in the mouse model. By genetically knockout out C3ar1 or inhibiting p-STAT3 signaling, we successfully prevented neuronal hypoexcitability and alleviated cognitive impairment in the mouse model. Therefore, targeting the C3aR and downstream p-STAT3 signaling pathways could serve as potential therapeutic approaches for mitigating POCD.

Astrocyte-neuron communication through the complement C3-C3aR pathway in Parkinson’s disease

Neuroinflammation and autoimmunity are pivotal in the pathogenesis of neurodegenerative diseases. Complement activation and involvement of astrocyte-neuron C3/C3aR pathway have been observed, yet the mechanisms influencing α-synuclein (α-syn) pathology and neurodegeneration remain unclear. In this study, elevated levels of complement C3 were detected in the plasma of α-syn PFF-induced mice and the substantia nigra of A53T transgenic mice. Colocalization of complement C3 with astrocytes was also observed. Overexpression of complement C3 exacerbated motor dysfunction, dopaminergic neuron loss, and phosphorylated α-syn expression in mice injected with α-syn preformed fibrils (α-syn PFFs). Conversely, downregulation of complement C3 protected α-syn PFF-induced mice. Molecular investigations revealed that inhibition of Toll-like receptor 2 (TLR2) or NF-κB reduced complement C3 expression in primary astrocytes following α-syn PFF treatment. Astrocyte-neuron communication via the C3/C3aR pathway influenced α-syn PFF-induced neuronal apoptosis and α-syn pathology, potentially through modulation of GSK3β. These findings underscore the critical role of astrocyte-neuron communication via the C3/C3aR pathway in PD pathogenesis, highlighting its potential as a therapeutic target.

Complement is increased in treatment resistant rectal cancer and modulates radioresistance

Resistance to neoadjuvant chemoradiation therapy (neo-CRT) is a significant clinical problem in the treatment of locally advanced rectal cancer. Identification of novel therapeutic targets and biomarkers predicting therapeutic response is required to improve patient outcomes. Increasing evidence supports a role for the complement system in resistance to anti-cancer therapy. In this study, increased expression of complement effectors C3 and C5 and increased production of anaphylatoxins, C3a and C5a, was observed in radioresistant rectal cancer cells. Modulation of the central complement effector, C3, was demonstrated to functionally alter the radioresponse, with C3 overexpression significantly enhancing radioresistance, whilst C3 inhibition significantly increased sensitivity to a clinically-relevant dose of radiation. Inhibition of C3 was demonstrated to increase DNA damage and alter cell cycle distribution, mediating a shift towards a radiosensitive cell cycle phenotype suggesting a role for C3 in reprogramming of the tumoural radioresponse. Expression of the complement effectors C3 and C5 was significantly increased in human rectal tumour tissue, as was expression of CFB, a component of the alternative pathway of activation. Elevated levels of C3a and C5b-9 in pre-treatment sera from rectal cancer patients was associated with subsequent poor responses to neo-CRT and poorer survival. Together these data demonstrate a role for complement in the radioresistance of rectal cancer and identify key complement components as potential biomarkers predicting response to neo-CRT and outcome in rectal cancer.

Impact of Preanalytical Procedures on Complement Biomarkers in Cerebrospinal Fluid and Plasma from Controls and Alzheimer's Disease Patients.

Studies comparing cerebrospinal fluid (CSF) and plasma complement proteins in Alzheimer's disease (AD) patients versus healthy controls (HC) have yielded inconsistent results. Discrepancies in the preanalytical sample handling could contribute to the heterogeneity in the reported findings. Using qualified immunoassays, we aimed at assessing the impact of preanalytical procedures on complement proteins in blood and CSF from AD patients and HCs. We supplemented HC and AD CSF/plasma with complement stabilizers and measured the complement proteins C4a, C4, C3a, C3, Factor Bb and Factor B by immunoassay. We tested the impact of freeze-thaw (FT) cycles on fluid complement proteins. Most complement proteins were mildly impacted by FT cycles in plasma but not CSF, except for C3a which displayed greater sensitivity to FTs in CSF than in plasma. In CSF, the effect of FTs on C3a was reduced but not prevented by the supplementation with EDTA (±Futhan). Our findings provide recommendations for CSF/plasma sample handling to ensure robust and reproducible complement biomarker analyses in AD.

Genetic, transcriptomic, histological, and biochemical analysis of progressive supranuclear palsy implicates glial activation and novel risk genes

Progressive supranuclear palsy (PSP), a rare Parkinsonian disorder, is characterized by problems with movement, balance, and cognition. PSP differs from Alzheimer’s disease (AD) and other diseases, displaying abnormal microtubule-associated protein tau by both neuronal and glial cell pathologies. Genetic contributors may mediate these differences; however, the genetics of PSP remain underexplored. Here we conduct the largest genome-wide association study (GWAS) of PSP which includes 2779 cases (2595 neuropathologically-confirmed) and 5584 controls and identify six independent PSP susceptibility loci with genome-wide significant (P < 5 × 10−8) associations, including five known (MAPT, MOBP, STX6, RUNX2, SLCO1A2) and one novel locus (C4A). Integration with cell type-specific epigenomic annotations reveal an oligodendrocytic signature that might distinguish PSP from AD and Parkinson’s disease in subsequent studies. Candidate PSP risk gene prioritization using expression quantitative trait loci (eQTLs) identifies oligodendrocyte-specific effects on gene expression in half of the genome-wide significant loci, and an association with C4A expression in brain tissue, which may be driven by increased C4A copy number. Finally, histological studies demonstrate tau aggregates in oligodendrocytes that colocalize with C4 (complement) deposition. Integrating GWAS with functional studies, epigenomic and eQTL analyses, we identify potential causal roles for variation in MOBP, STX6, RUNX2, SLCO1A2, and C4A in PSP pathogenesis.