Elevated Complement Research Articles

Neuropathological and cerebrospinal fluid correlates of choroid plexus inflammation in progressive multiple sclerosis

AbstractAmong the intrathecal inflammatory niches where compartmentalized inflammation persists and plays a pivotal role in progressive multiple sclerosis (MS), choroid plexus (CP) has recently received renewed attention. To better characterize the neuropathological/molecular correlates of CP in progressive MS and its potential link with other brain inflammatory compartments, such as perivascular spaces and leptomeninges, the levels, composition and phenotype of CP immune infiltration in lateral ventricles of the hippocampus were examined in 40 post‐mortem pathologically confirmed MS and 10 healthy donors, using immunochemistry/immunofluorescence and in‐situ sequencing. Significant inflammation was detected in the CP of 21 out of the 40 MS cases (52%). The degree of CP inflammation was found correlated with: number of CP macrophages (R: 0.878, p = 1.012 x 10‐13) and high frequency of innate immune cells expressing the markers MHC‐class II, CD163, CD209, CD11c, TREM2 and TSPO; perivascular inflammation (R: 0.509, p = 7.921 x 10‐4), and less with meningeal inflammation (R: 0.365, p = 0.021); number of active lesions (R: 0.51, p: 3.524 x 10‐5). However, it did not significantly correlate with any clinical/demographic characteristics of the examined population. In‐situ sequencing analysis of gene expression in the CP of 3 representative MS cases and 3 controls revealed regulation of inflammatory pathways mainly related to ‘type 2 immune response’, ‘defense to infections’, ‘antigen processing/presentation’. Analysis of 78 inflammatory molecules in paired post‐mortem CSF, the levels of fibrinogen (R: 0.640, p = 8.752 x 10‐6), PDGF‐bb (R: 0.470, p = 0.002), CXCL13 (R: 0.428, p = 0.006) and IL15 (R: 0.327, p = 0.040) were correlated with extent of CP inflammation. Elevated fibrinogen and complement deposition were found in CP and in underlying subependymal periventricular areas, according to “surface‐in” gradient associated with concomitant prominent microglia activation. CP inflammation, predominantly characterized by innate immunity, represents another key determinant of intrathecal, compartmentalised inflammation persisting in progressive MS, which may be possibly activated by fibrinogen and influence periventricular pathology, even without substantial association with clinical features.

Protein Network Alterations in G-CSF Treated Severe Congenital Neutropenia Patients and Beneficial Effects of Oral Health Intervention.

Severe congenital neutropenia (SCN) is a raredisorder characterized by diminished neutrophil levels. Despite granulocytecolony-stimulating factor (G-CSF) treatment, SCN patients remain still prone tosevere infections, including periodontal disease-a significant oral healthrisk. This study investigates the host proteome and metaproteome in saliva andgingival crevicular fluid (GCF) of G-CSF-treated patients. We used label-free quantitative proteomics on saliva and GCF samples from SCN patients before (n=10, mean age: 10.7±6.6 years) and after a 6-month oral hygiene intervention (n=9,mean age: 11.6±5.27 years), and from 12 healthy controls. We quantified 894 proteins in saliva (648 human,246 bacterial) and 756 proteins in GCF (493 human, 263 bacterial). Predominant bacterial genera included Streptococcus, Veillonella, Selenomonas, Corynebacterium, Porphyromonas, and Prevotella. SCN patients showed reduced antimicrobial peptides (AMPs) and elevated complement proteins compared tohealthy controls. Oral hygiene intervention improved oral epithelial conditionsand reduced both AMPs and complement proteins. SCN patients have aunique proteomic profile with reduced AMPs and increased complement proteins, contributing to infection susceptibility. Oral hygiene intervention not onlyimproved oral health in SCN patients but also offers potential overall therapeuticbenefits.

Immunotoxicity of legacy and alternative per- and polyfluoroalkyl substances on zebrafish larvae

Hexafluoropropylene oxide dimer acid (HFPO-DA) and perfluoroethylcyclohexane sulfonate (PFECHS) are increasingly used as alternatives for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). However, their immunotoxicity and underlying molecular mechanisms remain poorly understood. Here, to assess immunotoxic effects, zebrafish embryos were exposed to environmentally relevant concentrations of PFOA, PFOS, HFPO-DA, and PFECHS for four days. Results revealed that all four per- and polyfluoroalkyl substances (PFAS) resulted in decreased heart rate and spontaneous movement, and induced oxidative stress in zebrafish larvae. Notably, HFPO-DA exhibited more severe oxidative stress than PFOA. Immune dysfunction was observed, characterized by elevated cytokine, complement factor, nitric oxide, and neutrophil content, along with a significant decrease in lysozyme content. Transcriptomic analysis revealed the activation of Toll-like receptor (TLR)/NOD-like receptor (NLR)/RIG-I-like receptor (RLR) and associated downstream genes, indicating their pivotal role in PFAS-induced immunomodulation. Molecular docking simulations demonstrated stable interactions between PFAS and key receptors (TLR2, NOD2 and RIG-I). Overall, HFPO-DA and PFECHS exhibited immunotoxic effects in zebrafish larvae similar to legacy PFAS, providing important information for understanding the toxic mode of action of these emerging alternatives.

Elevated Complement Activation Fragments and C1q-Binding Circulating Immune Complexes in Varied Phases of Chikungunya Virus Infection.

Chikungunya virus (CHIKV) is a causative agent of a disease continuum, ranging from an acute transient chikungunya fever to chronic incapacitating viral arthralgia. The interaction between anti-CHIKV antibodies and the complement system has recently received attention. However, the contribution of complement activation in CHIKV-induced pathologies has not been fully elucidated. The present study was undertaken to delineate the possible contribution of complement activation in CHIKV-induced disease progression. In this study, using plasma specimens of chikungunya patients in the acute, chronic, and recovered phases of infection, we explicated the involvement of complement activation in CHIKV disease progression by ELISAs and Bio-Plex assays. Correlation analysis was carried out to demonstrate interrelation among C1q-binding IgG-containing circulating immune complexes (CIC-C1q), complement activation fragments (C3a, C5a, sC5b-9), and complement-modulated pro-inflammatory cytokines (IL-1β, IL-18,IL-6, andTNF-α). We detected elevated complement activation fragments, CIC-C1q, and complement-modulated cytokines in the varied patient groups compared with the healthy controls, indicating persistent activation of the complement system. Furthermore, we observed statistically significant correlations among CIC-C1q with complement activation fragments and C3a with complement modulatory cytokines IL-1β, IL-6, and IL-18 during the CHIKV disease progression. Taken together, the current data provide insight into the plausible association between CICs, complement activation, subsequent complement modulatory cytokine expression, and CHIKV etiopathology.

#2382 Renal tubule-derived EVs carrying complement 3 aggravate CKD vascular calcification by downregulating autophagy in vascular smooth muscle cells

Abstract Background and Aims Vascular calcification (VC) is a serious complication of chronic kidney disease (CKD) patients, recognized in KDIGO guidelines as a leading risk factor for cardiovascular diseases. Despite acknowledgment, the mechanisms of VC in CKD remain unclear. The kidneys intricately regulate blood vessel pathophysiology. Clinical studies suggest a correlation between elevated blood complement levels in CKD and arterial calcification, hinting at complement involvement in CKD-associated VC. Renal-origin complement, a significant source of circulating complement, activates in CKD. Extracellular vesicles (EVs), mediating intercellular communication, transport complement-related proteins in various physiological and pathological processes. Studies suggest that plasma EV rather than EV-depleted plasma causes pathogenic calcium salt deposition in smooth muscle cells. This study explores how renal-origin EVs carrying complement mediate CKD-associated VC. Method From October 2021 to August 2023, data from 110 clinical patients were gathered, encompassing both blood C3 levels and CT images of the thoracic aorta. Subsequently, we conducted a scoring analysis of the CT images and carried out correlation analyses. A CKD-associated VC model was induced by feeding C57BL/6j mice an adenine and high-phosphate diet for 16 weeks. Techniques, including WB, PCR, and immunofluorescence, detected complement activation and localization in renal tissues. EVs were isolated from kidney tissue and plasma and identified by NTA, electron microscopy, WB, etc. WB examined C3 and tubular markers of EVs. At the same time, the Elisa method was used to detect C3 in plasma, plasma EV, and EV-depleted plasma. Immunofluorescence investigated tubular-derived EVs uptake in calcified arteries. Tubular-derived EVs, C3a, C3aR receptor inhibitors (SB290157), and autophagy inhibitors (3-MA) intervened in high-phosphate-induced vascular smooth muscle cells (VSMCs). PCR and WB assessed calcification indicators, complement receptors, and autophagy-related indicators. Alizarin Red staining observed calcification nodules. Transcriptome sequencing was performed on control, high-phosphate, and renal tubular-derived EV intervention groups of VSMCs. An in vivo model infused renal tubular-derived EVs and injected C3aR inhibitors and autophagy inhibitors, measuring complement activation and VC indicators. Results There is a correlation between C3 and thoracic aorta calcium score in CKD patients, with a correlation coefficient of 0.3750 (P < 0.01). The CKD-associated VC mice model revealed complement C3 activation in renal tubules, secreted into the blood through EVs. The C3 proportion of plasma EV in CKD patients was significantly higher than that in the control group, but there was no statistical difference between the EV-depleted plasma control group and the CKD group. Immunofluorescence indicated tubular-derived EV uptake by the calcified vascular wall. In vitro, tubular-derived EVs enhanced VSMC osteogenic differentiation and upregulated C3aR, mimicking C3a intervention effects. C3aR receptor inhibitors produced opposing effects. Transcriptome sequencing suggested renal tubular-derived EVs downregulated VSMC autophagy-related pathways; in vitro autophagy inhibition reversed osteogenic differentiation. In vivo, reinfusing renal tubular-derived EVs exacerbated complement activation and VC, while injecting C3aR inhibitors and autophagy inhibitors alleviated CKD-associated VC. Conclusion This study confirms that tubular-derived EVs carrying C3 downregulate autophagy in VSMCs, mediating CKD-associated VC. These findings provide insights into understanding CKD-associated VC initiation and progression, revealing potential therapeutic targets.

Association of complement components with risk of colorectal cancer: A systematic review and meta-analysis.

Complement components could contribute to the tumor microenvironment and the systemic immune response. Nevertheless, their role in colorectal cancer (CRC) remains a contentious subject. To elucidate the relationship between complement components and CRC risk and clinical characteristics. Searches were conducted in PubMed, the Cochrane Library, and the China National Knowledge Infrastructure database until June 1, 2023. We included cohort studies encompassing participants aged ≥ 18 years, investigating the association between complement components and CRC. The studies were of moderate quality or above, as determined by the Agency for Healthcare Research and Quality. The meta-analysis employed fixed-effects or random-effects models based on the I² test, utilizing risk ratio (RR) and their corresponding 95% confidence interval (CI) for outcomes. Sensitivity and subgroup analyses were performed to validate the robustness of the collective estimates and identify the source of heterogeneity. Data from 15 studies, comprising 1631 participants that met the inclusion criteria, were included in the meta-analysis. Our findings indicated that protein levels of cluster of differentiation 46 (CD46) (RR = 3.66, 95%CI: 1.75-7.64, P < 0.001), CD59 (RR = 2.86, 95%CI: 1.36-6.01, P = 0.005), and component 1 (C1) (RR = 5.88, 95%CI: 1.75-19.73, P = 0.004) and serum levels of C3 (standardized mean difference = 1.82, 95%CI: 0.06-3.58, P = 0.040) were significantly elevated in patients with CRC compared to healthy controls. Strong expression of CD55 or CD59 was associated with a higher incidence of lymph node metastasis, whereas strong CD46 expression correlated with a higher incidence of tumor differentiation compared to low CD46 expression (P < 0.05 for all). Although specific pooled results demonstrated notable heterogeneity, subgroup analyses pointed to regional differences as the primary source of inconsistency among the studies. Our analysis underscores that increased levels of specific complement components are associated with a heightened risk of CRC, emphasizing the potential significance of monitoring elevated complement component levels.

Increased Complement Activation and Decreased ADAMTS13 Activity Are Associated with Genetic Susceptibility in Patients with Preeclampsia/HELLP Syndrome Compared to Healthy Pregnancies: An Observational Case-Controlled Study.

Preeclampsia is a progressive multi-systemic disorder characterized by proteinuria, critical organ damage, and new-onset hypertension. It can be further complicated by HELLP syndrome (hemolysis, elevated liver enzymes, low platelets), resulting in critical liver or renal damage, disseminated coagulation, and grand mal seizures. This study aimed to examine the involvement of ADAMTS13, von Willebrand, and the complement system in the pathogenesis of preeclampsia/HELLP syndrome. We studied 30 Caucasian preeclamptic pregnant women and a control group of 15 healthy pregnancies. Genetic sequencing of ADAMTS13 and complement regulatory genes (MiniSeq System, Illumina) was performed. The modified Ham test was used to check for complement activation, ADAMTS13 activity, von Willebrand antigen (vWFAg) levels, and soluble C5b-9 levels were measured. Patients with preeclampsia had a decreased ADAMTS13 activity and increased C5b-9 levels. The vWFAg was significantly correlated with ADAMTS13 activity (r = 0.497, p = 0.003). Risk-factor variants were found in the genes of ADAMTS13, C3, thrombomodulin, CFB, CFH, MBL2, and, finally, MASP2. A portion of pregnant women with preeclampsia showed a decline in ADAMTS13 activity, correlated with vWFAg levels. These patients also exhibited an elevated complement activation and high-risk genetic variants in regulatory genes. Further research is needed to determine if these factors can serve as reliable biomarkers.

Toll-Like Receptor mRNA Levels in Schizophrenia: Association With Complement Factors and Cingulate Gyrus Cortical Thinning.

Previous studies revealed innate immune system activation in people with schizophrenia (SZ), potentially mediated by endogenous pathogen recognition receptors, notably Toll-like receptors (TLR). TLRs are activated by pathogenic molecules like bacterial lipopolysaccharides (TLR1 and TLR4), viral RNA (TLR3), or both (TLR8). Furthermore, the complement system, another key component of innate immunity, has previously been linked to SZ. Peripheral mRNA levels of TLR1, TLR3, TLR4, and TLR8 were compared between SZ and healthy controls (HC). We investigated their relationship with immune activation through complement expression and cortical thickness of the cingulate gyrus, a region susceptible to immunological hits. TLR mRNA levels and peripheral complement receptor mRNA were extracted from 86 SZ and 77 HC white blood cells; structural MRI scans were conducted on a subset. We found significantly higher TLR4 and TLR8 mRNA levels and lower TLR3 mRNA levels in SZ compared to HC. TLRs and complemental factors were significantly associated in SZ and HC, with the strongest deviations of TLR mRNA levels in the SZ subgroup having elevated complement expression. Cortical thickness of the cingulate gyrus was inversely associated with TLR8 mRNA levels in SZ, and with TLR4 and TLR8 levels in HC. The study underscores the role of innate immune activation in schizophrenia, indicating a coordinated immune response of TLRs and the complement system. Our results suggest there could be more bacterial influence (based on TLR 4 levels) as opposed to viral influence (based on TLR3 levels) in schizophrenia. Specific TLRs were associated with brain cortical thickness reductions of limbic brain structures.

Locus coeruleus MRI contrast is associated with Complement factor C3b in cerebrospinal fluid

AbstractBackgroundDegeneration of the Locus coeruleus (LC) is associated with Alzheimer’s disease (AD) pathology and cognitive decline. Recent evidence from animal models indicates that this relationship may be mediated by neuroinflammation. Here we examined how LC MRI contrast is related to CSF biomarkers of neuroinflammation in humans.MethodThe LC as well as the Substantia nigra (SN) were visualized and segmented using neuromelanin‐sensitive T1‐weighted FLASH‐MRI images acquired at 3T and MRI contrast values were calculated as previously described (Betts et al., 2019b). A cohort of 65 participants with MRI contrast and CSF data from the DZNE longitudinal cognitive impairment and dementia (DELCODE) study (20 HC, 22 SCD, 16 MCI, 7 AD dementia; 53.8% female) were included in the analyses. We performed correlational analyses to test for associations between LC and SN contrast with a panel of 4 Principal Components (PC) created from a Principial Component Analysis on 16 individual inflammation‐related CSF biomarkers (Fig. 1). Both bivariate and partial correlation analyses were performed between PCs and MRI contrast values using sex, age, site and CSF levels of AD pathology, namely Aß42/40‐ratio and phosphorylated tau, as covariates (see Fig. 2).ResultWe found a significant positive association between LC MRI contrast and the inflammatory component PC4 including the proinflammatory complement factors C3 and C3b across the entire sample (r = 0.365, p = 0.003). Additional post‐hoc correlational analyses showed this association with LC MRI contrast was mainly due to a correlation with C3b (r = 0.349, p = 0.004). A significant positive association was still observed (r = 0.347, p = 0.008) in a subgroup of individuals comprising healthy older adults and individuals with a risk of AD dementia (HC, SCD and MCI) as shown in Fig. 2. In contrast, no significant associations between SN MRI contrast and any neurodegenerative or inflammatory measure were observed indicating effects were specific to the LC.ConclusionThe results demonstrate LC MRI contrast is associated with complement factors in CSF, in particular complement factor C3b in healthy older adults and individuals with a risk of AD dementia. Further analyses are required to determine if elevated complement factors may predict degeneration of the LC and subsequent cognitive decline.

Network‐based Genetic Subtyping for Target Prioritization and Drug Repositioning: The Artificial Intelligence for Alzheimer’s Disease (AI4AD) Consortium

AbstractBackgroundAlzheimer disease (AD) is a progressive neurodegenerative disease with complicated underlying disease mechanisms. The clinical and neuropathological heterogeneity of AD may be explained by specific disease mechanisms at a brain cell‐level. We postulate that the path to effective treatment of AD depends on identifying distinctive subtypes linking to specific disease mechanisms at brain cellular level.MethodWe developed a novel precision medicine framework using polygenic risk scores defined by co‐regulated cellular networks to stratify individuals into low and high‐risk groups (genetic subtypes) for brain cell‐type specific networks. We prioritized genes from the cell‐based networks using a graph‐based ranking (PageRank) algorithm. We investigated molecular signatures of the prioritized genes for the subtypes using autopsied brains from the Framingham Heart Study (FHS). We validated the signatures using isogenic APOE lines of human pluripotent stem cell (hiPSC)‐derived astrocytes. Existing drugs targeting for the genetic subtypes were identified using drug perturbation database and clustering algorithms using compound structures from the PubChem databaseResultWe identified six preserved and AD associated co‐expressed gene networks for astrocytes, oligodendrocytes, and oligodendrocyte progenitor cells. The top‐ranked astrocyte network was enriched with Parkinson’s disease, Alzheimer’s disease, mineral absorption, and ribosome pathways. The most important gene in the astrocyte network was the APOE gene, which its expression was increased in AD compared in control brains with elevated complement C4A level. We confirmed elevated expression of both APOE and C4A levels in APOE4 compared in APOE3 hiPSC‐derived astrocytes. We identified three drugs targeting the astrocyte subtype, all of them previously modulated expression of the prioritized genes in the drug perturbation database. Clustering algorithm identified multiple compounds targeting the prioritized genes in the astrocyte network with at least 80% similarity in structure.ConclusionThe newly established framework provided the potential implication in genetic subtype driven drug repositioning in AD. In future, we will develop novel graph neural network approaches to identify comprehensive genetic subtypes and drugs targeting the subtypes in collaboration with internal and external members from the AI4AD consortium.

A prospective multi-institutional study of eculizumab to treat high-risk stem cell transplantation–associated TMA

AbstractHigh-risk, complement mediated, untreated transplant-associated thrombotic microangiopathy (hrTMA) has dismal outcomes due to multi-organ dysfunction syndrome (MODS). The complement C5 blocker eculizumab shows promising results in hrTMA, but has not been prospectively studied in hematopoietic stem cell transplant (HCT) recipients. We performed the first multi-institutional prospective study in children and young adults to evaluate eculizumab as an early targeted intervention for hrTMA/MODS. We hypothesized that eculizumab would more than double survival in HCT recipients with hrTMA, compared to our prior study of prospectively screened, untreated hrTMAs serving as historical controls. HrTMA features (elevated terminal complement (sC5b-9) and proteinuria measured by random urine protein/creatinine ratio (≥1mg/mg)) were required for inclusion. The primary endpoint was survival at 6 six-months from hrTMA diagnosis. Secondary endpoints were cumulative incidence of MODS 6 months after hrTMA diagnosis and 1-year posttransplant survival. Eculizumab dosing included intensive loading, induction, and maintenance phases for up to 24 weeks of therapy. All 21 evaluated study subjects had MODS. Primary and secondary study endpoints were met by demonstrating survival of 71% (P < .0001) 6 months after hrTMA diagnosis and 62% 1 year after transplant. Of fifteen survivors, 11 (73%) fully recovered organ function and are well. Our study demonstrates significant improvement in survival and recovery of organ function in hrTMA using an intensified eculizumab dosing and real time biomarker monitoring. This study serves as a benchmark for planning future studies that should focus on preventative measures or targeted therapy to be initiated prior to organ injury. This trial was registered at www.clinicaltrials.gov as #NCT03518203.

A Case of a Serum Sickness-Like Reaction After Postexposure Rabies Prophylaxis

BackgroundSerum sickness secondary to rabies postexposure prophylaxis is not well documented in the medical literature. Our case describes serum sickness after exposure to human-derived rabies immunoglobulin (HRIG) and three human diploid rabies vaccines (HDCV) in a young adult male. Case ReportA 30-year-old previously healthy male patient presented to the Emergency Department with complaints of fever, rash, and jaundice, and had a hospital course complicated by biliary stenosis likely secondary to reactive periportal lymphadenopathy. His initial laboratory values demonstrated obstructive jaundice and slightly elevated complement component 4 levels. These symptoms likely are due to the course of HRIG and HDCV vaccines the patient completed after being exposed to a rabies-positive bat in his home. The patient was hospitalized for 8 days, during which he underwent an endoscopic retrograde cholangiopancreatography with sphincterotomy and biliary stenting. He had one repeat hospitalization for acute blood loss anemia attributed to sphincterotomy, which did not require transfusion or further intervention. Liver biopsy showed cholestatic hepatitis. Why Should an Emergency Physician Be Aware of This?Medical literature describing serum sickness or a serum sickness-like reaction occurring from exposure to HRIG or HDCV is sparse despite the commonality of postexposure rabies prophylaxis in health care. It is important to educate practitioners on this potential complication and highlight next potential consultations and treatments.

Elevated complement C3 and increased CD8 and type 1 helper lymphocyte T populations in patients with post-COVID-19 condition

BackgroundBiological markers associated to post-COVID-19 condition (PCC) have not been clearly identified. MethodsEighty-two patients attending our post-COVID-19 outpatient clinic were recruited and classified as fully recovered (40.2%) or presenting with PCC (59.8%). Clinical and radiological data, laboratory markers, cytokines, and lymphocyte populations were analyzed. ResultsMedian number of days after hospitalization was 78.5 [p25-p75: 60–93] days. PCC was significantly more frequent in women, in patients with a previously critical COVID-19, and in those with two or more comorbidities. No differences were found in lymphocyte counts, ferritin, C-reactive protein, D-dimer or sCD25, IL-1β, IL-1Ra, IL-6, CXCL8, IL-17A, IL-18, IL-22, IFN-γ, TNF-α, and IL-10 cytokines levels. PCC patients showed significantly higher levels of complement factor C3 than fully recovered patients: median C3 128 mg/dL [p25-p75:107–135] vs 111 mg/dL [p25-p75: 100–125] (p =.005), respectively. In the flow cytometry assessment of peripheral blood lymphocyte subpopulations, PCC patients showed significantly increased CD8 populations compared to fully recovered patients: median CD8: 529 [p25-p75: 384–683] vs 370/mm3 [p25-p75:280–523], p =.007. When type 1, 2, 17/22, and 17.1 helper and follicular T lymphocyte subpopulations were analyzed, the frequency of Th1 was significantly higher in PCC patients compared to fully recovered patients (30% vs 38.5%, p =.028). ConclusionPatients with a post-COVID-19 condition showed significantly increased immunological parameters of inflammation (complement factor C3 and CD8 and Th1 T lymphocyte populations) compared to fully recovered patients. These parameters could be used as biological markers of this condition.

Investigating the potential associated factors and developing a risk model for interstitial lung disease in Chinese patients with systemic lupus erythematosus.

This study aimed to explore the risk factors for interstitial lung disease (ILD) in Chinese patients with systemic lupus erythematosus (SLE). This study recruited 40 SLE patients with ILD (SLE-ILD) and 40 SLE patients without ILD (SLE-non-ILD). Clinical data were collected from all patients, including basic clinical characteristics, affected organ systems, biochemical indexes, autoantibodies, and immunocytes. Compared with the SLE-non-ILD patients, SLE-ILD patients presented older age (p < 0.001), dry cough (p = 0.006), "velcro-like" crackles (p = 0.021), Raynaud's phenomenon (p = 0.040), elevated complement 3 (C3) level (p = 0.044), and lower SLE disease activity index score (p = 0.013) and cluster of difference-3cell count (p = 0.043). Multivariate logistic regression analysis showed that older age (p < 0.001, odds ratio [OR]: 1.212), female sex (p = 0.022, OR: 37.075), renal involvement (p = 0.011, OR: 20.039), C3 level (p = 0.037, OR: 63.126), immunoglobulin (Ig) M level (p = 0.005, OR: 5.082), and positive anti-U1 small ribonucleoprotein antibody (anti-nRNP) result (p = 0.003, OR: 19.886) were independent ILD risk factors in SLE patients. Consequently, the ILD risk model in patients with SLE was constructed based on statistically significant variables from the multivariate logistic regression analysis, which significantly correlated with ILD risk, with an area under the curve of 0.887 (95% confidence interval: 0.815-0.960) using receiver operating characteristic curve analysis. Age, female sex, renal involvement, C3 level, IgM level, and a positive anti-nRNP result are independent risk factors for ILD. Furthermore, their combination model is closely associated with an increased ILD risk in Chinese patients with SLE.

Elevated plasma complement factor H related 5 protein is associated with venous thromboembolism

Venous thromboembolism (VTE) is a common, multi-causal disease with potentially serious short- and long-term complications. In clinical practice, there is a need for improved plasma biomarker-based tools for VTE diagnosis and risk prediction. Here we show, using proteomics profiling to screen plasma from patients with suspected acute VTE, and several case-control studies for VTE, how Complement Factor H Related 5 protein (CFHR5), a regulator of the alternative pathway of complement activation, is a VTE-associated plasma biomarker. In plasma, higher CFHR5 levels are associated with increased thrombin generation potential and recombinant CFHR5 enhanced platelet activation in vitro. GWAS analysis of ~52,000 participants identifies six loci associated with CFHR5 plasma levels, but Mendelian randomization do not demonstrate causality between CFHR5 and VTE. Our results indicate an important role for the regulation of the alternative pathway of complement activation in VTE and that CFHR5 represents a potential diagnostic and/or risk predictive plasma biomarker.

The Role of NETosis and Complement Activation in COVID-19-Associated Coagulopathies.

Inflammation-induced coagulopathy is a common complication associated with coronavirus disease 2019 (COVID-19). We aim to evaluate the association of NETosis and complement markers with each other as well as their association with thrombogenicity and disease severity in COVID-19. The study included hospitalized patients with an acute respiratory infection: patients with SARS-CoV2 infection (COVpos, n = 47) or either pneumonia or infection-triggered acute exacerbated COPD (COVneg, n = 36). Our results show that NETosis, coagulation, and platelets, as well as complement markers, were significantly increased in COVpos patients, especially in severely ill COVpos patients. NETosis marker MPO/DNA complexes correlated with coagulation, platelet, and complement markers only in COVpos. Severely ill COVpos patients showed an association between complement C3 and SOFA (R = 0.48; p ≤ 0.028), C5 and SOFA (R = 0.46; p ≤ 0.038), and C5b-9 and SOFA (R = 0.44; p ≤ 0.046). This study provides further evidence that NETosis and the complement system are key players in COVID-19 inflammation and clinical severity. Unlike previous studies that found NETosis and complement markers to be elevated in COVID-19 patients compared to healthy controls, our findings show that this characteristic distinguishes COVID-19 from other pulmonary infectious diseases. Based on our results, we propose that COVID-19 patients at high risk for immunothrombosis could be identified via elevated complement markers such as C5.

Microglia-dependent excessive synaptic pruning leads to cortical underconnectivity and behavioral abnormality following chronic social defeat stress in mice

Synapse loss in medial prefrontal cortex (mPFC) has been implicated in stress-related mood disorders, such as depression. However, the exact effect of synapse elimination in the depression and how it is triggered are largely unknown. Through repeated longitudinal imaging of mPFC in the living brain, we found both presynaptic and postsynaptic components were declined, together with the impairment of synapse remodeling and cross-synaptic signal transmission in the mPFC during chronic stress. Meanwhile, chronic stress also induced excessive microglia phagocytosis, leading to engulfment of excitatory synapses. Further investigation revealed that the elevated complement C3 during the stress acted as the tag of synapses to be eliminated by microglia. Besides, chronic stress induced a reduction of the connectivity between the mPFC and neighbor regions. C3 knockout mice displayed significant reduction of synaptic pruning and alleviation of disrupted functional connectivity in mPFC, resulting in more resilience to chronic stress. These results indicate that complement-mediated excessive microglia phagocytosis in adulthood induces synaptic dysfunction and cortical hypo-connectivity, leading to stress-related behavioral abnormality.

Efficacy and safety of belimumab for the treatment of refractory childhood-onset systemic lupus erythematosus: A single-center, real-world, retrospective study.

This study aimed to investigate the efficacy and safety of belimumab for treating children with refractory childhood-onset systemic lupus erythematosus (cSLE). Twenty-six cSLE patients who received belimumab treatment in our hospital from January 2020 to September 2021 (23 of them for more than 52 weeks) were enrolled in this study. Their clinical and laboratory data, assessment of disease activity, glucocorticoid dosage, and treatment-emergent adverse events (TEAEs) were retrieved for analysis. The paired samples t-test and the nonparametric test were used to compare the baseline and post-treatment data. The mean age of onset was 10.3 ± 2.4 years old; the mean disease duration was 41.6 ± 37.4 months; the median Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score was 10 (P 25, P 75: 3, 17); and the mean Physician's Global Assessment (PGA) score at baseline was 1.9 ± 1.0. Compared with the baseline values, there was a significant decrease in the 24-h urine protein quantifications at 24 and 52 weeks of treatment (P<0.05) as well as an elevated complement (C) 3 and C4 levels at 4, 12, 24, and 52 weeks of treatment. In addition, the SLEDAI-2K and PGA scores as well as the percentage of CD19+ B cells were significantly decreased at 12, 24, and 52 weeks of treatment compared with the baseline values (P<0.05). The dosage of glucocorticoid at 4, 12, 24, and 52 weeks of treatment was significantly less than that at baseline or the previous follow-up (P<0.05). At 52 weeks, 14 subjects (53.8%) achieved Lupus Low Disease Activity State (LLDAS), and 4 subjects (15.4%) reached clinical remission (CR). At the last follow-up, 16 subjects (61.5%) achieved LLDAS, and 10 subjects (38.5%) reached CR. Belimumab treatment can significantly improve laboratory indicators, reduce disease activity, and decrease the dosage of glucocorticoid required in children with cSLE. Moreover, it has a good safety profile.

Elevated complement component 8 gamma levels in astrocyte-derived exosomes are associated with cognitive impairment in obstructive sleep apnea patients without dementia

The complement system plays a crucial role in cognitive impairment in obstructive sleep apnea (OSA). The present study aimed to investigate the connections between complement component 8 gamma (C8G) levels in astrocyte-derived exosomes (ADEs) and cognitive impairment in OSA patients without dementia. This cross-sectional cohort study recruited 274 participants without dementia, including 124 OSA patients with mild cognitive impairment (MCI), 100 OSA patients without MCI, and 50 healthy control subjects. Enrolled participants underwent polysomnography (PSG) evaluation, neuropsychological scale assessment, magnetic resonance imaging scanning, and collection of peripheral blood samples for quantification of complement proteins in ADEs. The findings showed higher C8G concentrations in ADEs from OSA patients with MCI than in the controls and OSA without MCI group. Logistic regression analysis suggested that C8G levels in ADEs were independently associated with MCI in OSA patients. Multivariable linear regression analysis demonstrated that C8G levels in ADEs were significantly correlated with global cognitive scores and all cognitive subdomain scores after adjusting for demographic factors (age, sex, education), vascular risk factors (Body mass index, history of hypertension, diabetes, dyslipidemia), depressive symptoms measures, and apnea-hypopnea index (AHI) values. The levels of C8G were linearly positively related to the white matter hyperintensity (WMH) volumes in Pearson's correlation analysis. Our research confirmed that C8G levels are significantly associated with cognitive impairment in OSA patients, which paves the way for novel therapeutic targets for neurocognitive dysfunction progression in OSA patients in the future.

Quantitative Proteomic Analysis Reveals Yeast Cell Wall Products Influence the Serum Proteome Composition of Broiler Chickens.

With an ever-growing market and continual financial pressures associated with the prohibition of antibiotic growth promoters, the poultry industry has had to rapidly develop non-antibiotic alternatives to increase production yields. A possible alternative is yeast and its derivatives, such as the yeast cell wall (YCW), which have been proposed to confer selected beneficial effects on the host animal. Here, the effect of YCW supplementation on the broiler chicken was investigated using a quantitative proteomic strategy, whereby serum was obtained from three groups of broilers fed with distinct YCW-based Gut Health Products (GHP) or a control basal diet. Development of a novel reagent enabled application of ProteoMiner™ technology for sample preparation and subsequent comparative quantitative proteomic analysis revealed proteins which showed a significant change in abundance (n = 167 individual proteins; p < 0.05); as well as proteins which were uniquely identified (n = 52) in, or absent (n = 37) from, GHP-fed treatment groups versus controls. An average of 7.1% of proteins showed changes in abundance with GHP supplementation. Several effects of these GHPs including immunostimulation (via elevated complement protein detection), potential alterations in the oxidative status of the animal (e.g., glutathione peroxidase and catalase), stimulation of metabolic processes (e.g., differential abundance of glyceraldehyde-3-phosphate dehydrogenase), as well as evidence of a possible hepatoprotective effect (attenuated levels of serum α-glutathione s-transferase) by one GHP feed supplement, were observed. It is proposed that specific protein detection may be indicative of GHP efficacy to stimulate broiler immune status, i.e., may be biomarkers of GHP efficacy. In summary, this work has developed a novel technology for the preparation of high dynamic range proteomic samples for LC-MS/MS analysis, is part of the growing area of livestock proteomics and, importantly, provides evidential support for beneficial effects that GHP supplementation has on the broiler chicken.