Complement C1s as a diagnostic marker and therapeutic target: Progress and propective

Impact of a Heterozygous C1RR301P/WT Mutation on Collagen Metabolism and Inflammatory Response in Human Gingival Fibroblasts

Periodontal Ehlers-Danlos syndrome arising from heterozygous pathogenic mutation in C1R and/or C1S genes is an autosomal-dominant disorder characterized by early-onset periodontitis. Due to the difficulties in obtaining and culturing the patient-derived gingival fibroblasts, we established a model system by introducing a heterozygous C1RR301P/WT mutation into human TERT-immortalized gingival fibroblasts (hGFBs) to investigate its specific effects on collagen metabolism and inflammatory responses. A heterozygous C1RR301P/WT mutation was introduced into hGFBs using engineered prime editing. The functional consequences of this mutation were assessed at cellular, molecular, and enzymatic levels using a variety of techniques, including cell growth analysis, collagen deposition quantification, immunocytochemistry, enzyme-linked immunosorbent assay, and quantitative real-time reverse transcription polymerase chain reaction. The C1RR301P/WT-mutated hGFBs (mhGFBs) exhibited normal morphology and growth rate compared to wild-type hGFBs. However, mhGFBs displayed upregulated procollagen α1(V), MMP-1, and IL-6 mRNA expression while simultaneously downregulating collagen deposition and C1r protein levels. A modest accumulation of unfolded collagens was observed in mhGFBs. The mhGFBs exhibited a heightened inflammatory response, with a more pronounced increase in MMP-1 and IL-6 mRNA expression compared to TNF-α/IL-1β-stimulated hGFBs. Unlike cytokine-stimulated hGFBs, cytokine-stimulated mhGFB did not increase C1R, C1S, procollagen α1(III), and procollagen α1(V) mRNA expression. Our results suggest that the C1RR301P/WT mutation specifically disrupts collagen metabolism and inflammatory pathways in hGFBs, highlighting the mutation's role in these processes. While other cellular functions appear largely unaffected, these findings underscore the potential of targeting collagen metabolism and inflammation for therapeutic interventions in pEDS.

Complement activity and autophagy are dysregulated in the lungs of patients with nonresolvable COVID-19 requiring lung transplantation

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced coronavirus disease 2019 (COVID-19) pandemic has challenged the current understanding of the complement cascade mechanisms of host immune responses during infection-induced nonresolvable lung disease. While the complement system is involved in opsonization and phagocytosis of the invading pathogens, uncontrolled complement activation also leads to aberrant autophagic response and tissue damage. Our recent study revealed unique pathologic and fibrotic signature genes associated with epithelial bronchiolization in the lung tissues of patients with nonresolvable COVID-19 (NR-COVID-19) requiring lung transplantation. However, there is a knowledge gap if complement components are modulated to contribute to tissue damage and the fibrotic phenotype during NR-COVID-19. We, therefore, aimed to study the role of the complement factors and their corresponding regulatory proteins in the pathogenesis of NR-COVID-19. We further examined the association of complement components with mediators of the host autophagic response. We observed significant upregulation of the expression of the classical pathway factor C1qrs and alternative complement factors C3 and C5a, as well as the anaphylatoxin receptor C5aR1, in NR-COVID-19 lung tissues. Of note, complement regulatory protein, decay accelerating factor (DAF; CD55) was significantly downregulated at both transcript and protein levels in the NR-COVID-19 lungs, indicating a dampened host protective response. Furthermore, we observed significantly decreased levels of the autophagy mediators PPARγ and LC3a/b, which was corroborated by decreased expression of factor P and the C3b receptor CR1, indicating impaired clearance of damaged cells that may contribute to the fibrotic phenotype in NR-COVID-19 patients. Thus, our study revealed previously unrecognized complement dysregulation associated with impaired cell death and clearance of damaged cells, which may promote NR-COVID-19 in patients, ultimately necessitating lung transplantation. The identified network of dysregulated complement cascade activity indicates the interplay of regulatory factors and the receptor-mediated modulation of host immune and autophagic responses as potential therapeutic targets for treating NR-COVID-19.

[Berberine ameliorates coronary artery endothelial cell injury in Kawasaki disease through complement and coagulation cascades]

OBJECTIVES

To explore the role of berberine (BBR) in ameliorating coronary endothelial cell injury in Kawasaki disease (KD) by regulating the complement and coagulation cascade.

METHODS

Human coronary artery endothelial cells (HCAEC) were divided into a healthy control group, a KD group, and a BBR treatment group (n=3 for each group). The healthy control group and KD group were supplemented with 15% serum from healthy children and KD patients, respectively, while the BBR treatment group received 15% serum from KD patients followed by the addition of 20 mmol/L BBR. Differential protein expression was analyzed and identified using isobaric tags for relative and absolute quantitation technology and liquid chromatography-tandem mass spectrometry, followed by GO functional enrichment analysis and KEGG signaling pathway enrichment analysis of the differential proteins. Western blot was used to detect differential protein expression.

RESULTS

A total of 518 differential proteins were identified between the KD group and the healthy control group (300 upregulated proteins and 218 downregulated proteins). A total of 422 differential proteins were identified between the BBR treatment group and the KD group (221 upregulated proteins and 201 downregulated proteins). Bioinformatics analysis showed that compared to the healthy control group, the differential proteins in the KD group were enriched in the complement and coagulation cascade and ribosome biogenesis in eukaryotes. Compared to the KD group, the differential proteins in the BBR treatment group were also enriched in the complement and coagulation cascade and ribosome biogenesis in eukaryotes. Western blot results indicated that compared to the healthy control group, the expression of complement C1q subcomponent subunit C (C1QC), kininogen-1 (KNG1), complement C1s subcomponent (C1S), and C4b-binding protein alpha chain (C4BPA) was increased in the KD group (P<0.05). Compared to the KD group, the expression of KNG1, C1S, C1QC, and C4BPA was decreased in the BBR treatment group (P<0.05).

CONCLUSIONS

The complement and coagulation cascade may be involved in the regulation of BBR treatment for coronary injury in KD, and C1QC, KNG1, C1S, and C4BPA may serve as biomarkers for this treatment.

Complement C1S is a potential prognostic biomarker and associated with M2 macrophage infiltration in gliomas: From bioinformatics to comprehensive experimental validation

Glioma is the most common malignant tumor of the central nervous system, and the ability of traditional clinical treatment to prolong the survival of glioma patients is limited. A substantial body of evidence underscores the pivotal role of the immune system in eradicating malignant cells and impeding tumor metastasis. Consequently, tumor immunotherapy has become a promising avenue to address the clinical conundrum faced by glioma patients. The complement system is a natural immune system that is an important line of defense in the immune response. C1S plays a key role in activating the classical complement system. Nevertheless, few studies have focused on the role of C1S in glioma tumorigenesis and progression. In this study, we demonstrated that C1S was upregulated in GBM (Grade IV) and low-grade gliomas (LGG, Grade II-III) by combining glioma cohorts from multiple public databases with our internal independent cohorts and that increased C1S expression levels predict a poor prognosis for gliomas. Cox regression analysis identified C1S as an important prognostic indicator for glioma patients. In addition, gene functional enrichment analysis demonstrated that C1S was involved in cellular immunity, T-cell activation, macrophage differentiation, and cell proliferation. Further experiments demonstrated that C1S facilitates tumor cell proliferation, cell migration and intracranial tumor growth in nude mice. More importantly, we evaluated the role of C1S in immune infiltration. These results suggested that C1S was closely related to a variety of immune cell types in glioma, especially M2 macrophages. Our findings were further validated via glioma tissue microarray immunohistochemical analysis and an M2 macrophage infiltration assay. Together, these findings revealed the underlying critical role of C1S in glioma tumorigenesis, progression, and the tumor immune microenvironment, contributing to further understanding of glioma pathogenesis and guiding immunotherapy.

Pan-cancer analysis identifies venous thromboembolism-related genes F3, PLAT, and C1S as potential prognostic biomarkers for glioblastoma and lower grade glioma

Venous thromboembolism (VTE) is a prevalent complication among patients with cancer, contributing significantly to morbidity and mortality. However, the relationship between VTE-related genes (VRGs) and their potential impact on prognosis, immune response, and therapeutic targets in various cancer types remains unclear. Based on the coagulation and complement pathways, we identified hub VRGs that play a role in regulating the immune response in cancer. Specifically, coagulation factor III (F3), plasminogen activator (PLAT) and complement C1s (C1S) were identified as genes that exhibit high expression levels, positively correlating with tumor stemness and copy number variations, while inversely correlating with methylation levels, in particular cancer types. Pan-cancer survival analysis revealed detrimental effects of these VRGs in several cancer types, notably in glioblastoma and lower grade glioma (GMBLGG). Further analysis using receiver operating characteristic (ROC) curves demonstrated a high accuracy of F3, PLAT and C1S in predicting outcomes in GBMLGG, with area under the curve (AUC) values ranging from 0.78 to 0.9. Validation of the prognostic value of these three genes in GMBLGG was conducted using an independent Gene Expression Omnibus (GEO) dataset. Additionally, gene-drug association analysis identified ciclosporin, ouabain and 6- mercaptopurine, which all exhibit immunosuppressive properties, as potential therapeutic options for tumor patients exhibiting high F3, PLAT or C1S expression, respectively. In summary, our findings provide a bioinformatics perspective on VRGs in pan-cancer, highlighting the pivotal roles of F3, PLAT and C1S, which could potentially be therapeutically exploited and targeted in several cancers, especially in GBMLGG.

The expression and biological role of complement C1s in esophageal squamous cell carcinoma

The present work focused on investigating the role of the altered expression of complement C1s in proliferation and apoptosis of esophageal squamous cell carcinoma (ESCC) cells and explore its biological functions in ESCC, so as to lay a theoretical foundation and provide certain clinical reference for diagnosing and treating ESCC. Complement C1s expression within ESCC was assessed, and its clinical pathological characteristics in ESCC patients were analyzed. Subsequently, in vitro experiments were performed to further explore the mechanisms by which complement C1s affected ESCC. According to the results, complement C1s expression within ESCC markedly increased relative to adjacent non-cancerous samples. High C1s expression showed positive relation to race, residual lesion, and tumor location of ESCC patients. Complement C1s affected ESCC cell proliferation and apoptosis. Notably, C1s knockdown significantly inhibited ESCC cell proliferation and enhanced their apoptosis. C1s suppressed ESCC cell proliferation via Wnt1/β-catenin pathway and promoted their apoptosis through modulating the expression of Bcl2, Bax, and cleaved-caspase3.

C1s targeting antibodies inhibit the growth of cutaneous squamous carcinoma cells

Cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer. The incidence of cSCC is increasing globally and the prognosis of metastatic disease is poor. Currently there are no specific targeted therapies for advanced or metastatic cSCC. We have previously shown abundant expression of the complement classical pathway C1 complex components, serine proteases C1r and C1s in tumor cells in invasive cSCCs in vivo, whereas the expression of C1r and C1s was lower in cSCCs in situ, actinic keratoses and in normal skin. We have also shown that knockdown of C1s expression results in decreased viability and growth of cSCC cells by promoting apoptosis both in culture and in vivo. Here, we have studied the effect of specific IgG2a mouse monoclonal antibodies TNT003 and TNT005 targeting human C1s in five primary non-metastatic and three metastatic cSCC cell lines that show intracellular expression of C1s and secretion of C1s into the cell culture media. Treatment of cSCC cells with TNT003 and TNT005 significantly inhibited their growth and viability and promoted apoptosis of cSCC cells. These data indicate that TNT003 and TNT005 inhibit cSCC cell growth in culture and warrant further investigation of C1s targeted inhibition in additional in vitro and in vivo models of cSCC.

The role of microglia heterogeneity in synaptic plasticity and brain disorders: Will sequencing shed light on the discovery of new therapeutic targets?

Microglia play a crucial role in interacting with neuronal synapses and modulating synaptic plasticity. This function is particularly significant during postnatal development, as microglia are responsible for removing excessive synapses to prevent neurodevelopmental deficits. Dysregulation of microglial synaptic function has been well-documented in various pathological conditions, notably Alzheimer's disease and multiple sclerosis. The recent application of RNA sequencing has provided a powerful and unbiased means to decipher spatial and temporal microglial heterogeneity. By identifying microglia with varying gene expression profiles, researchers have defined multiple subgroups of microglia associated with specific pathological states, including disease-associated microglia, interferon-responsive microglia, proliferating microglia, and inflamed microglia in multiple sclerosis, among others. However, the functional roles of these distinct subgroups remain inadequately characterized. This review aims to refine our current understanding of the potential roles of heterogeneous microglia in regulating synaptic plasticity and their implications for various brain disorders, drawing from recent sequencing research and functional studies. This knowledge may aid in the identification of pathogenetic biomarkers and potential factors contributing to pathogenesis, shedding new light on the discovery of novel drug targets. The field of sequencing-based data mining is evolving toward a multi-omics approach. With advances in viral tools for precise microglial regulation and the development of brain organoid models, we are poised to elucidate the functional roles of microglial subgroups detected through sequencing analysis, ultimately identifying valuable therapeutic targets.

Integrating single-cell and bulk transcriptomic analyses to develop a cancer-associated fibroblast-derived biomarker for predicting prognosis and therapeutic response in breast cancer

Background

Cancer-associated fibroblasts (CAFs) contribute to the progression and treatment of breast cancer (BRCA); however, risk signatures and molecular targets based on CAFs are limited. This study aims to identify novel CAF-related biomarkers to develop a risk signature for predicting the prognosis and therapeutic response of patients with BRCA.

Methods

CAF-related genes (CAFRGs) and a risk signature based on these genes were comprehensively analyzed using publicly available bulk and single-cell transcriptomic datasets. Modular genes identified from bulk sequencing data were intersected with CAF marker genes identified from single-cell analysis to obtain reliable CAFRGs. Signature CAFRGs were screened via Cox regression and least absolute shrinkage and selection operator (LASSO) analyses. Multiple patient cohorts were used to validate the prognosis and therapeutic responsiveness of high-risk patients stratified based on the CAFRG-based signature. In addition, the relationship between the CAFRG-based signature and clinicopathological factors, tumor immune landscape, functional pathways, chemotherapy sensitivity and immunotherapy sensitivity was examined. External datasets were used and sample experiments were performed to examine the expression pattern of MFAP4, a key CAFRG, in BRCA.

Results

Integrated analyses of single-cell and bulk transcriptomic data as well as prognostic screening revealed a total of 43 prognostic CAFRGs; of which, 14 genes (TLN2, SGCE, SDC1, SAV1, RUNX1, PDLIM4, OSMR, NT5E, MFAP4, IGFBP6, CTSO, COL12A1, CCDC8 and C1S) were identified as signature CAFRGs. The CAFRG-based risk signature exhibited favorable efficiency and accuracy in predicting survival outcomes and clinicopathological progression in multiple BRCA cohorts. Functional enrichment analysis suggested the involvement of the immune system, and the immune infiltration landscape significantly differed between the risk groups. Patients with high CAF-related risk scores (CAFRSs) exhibited tumor immunosuppression, enhanced cancer hallmarks and hyposensitivity to chemotherapy and immunotherapy. Five compounds were identified as promising therapeutic agents for high-CAFRS BRCA. External datasets and sample experiments validated the downregulation of MFAP4 and its strong correlation with CAFs in BRCA.

Conclusions

A novel CAF-derived gene signature with favorable predictive performance was developed in this study. This signature may be used to assess prognosis and guide individualized treatment for patients with BRCA.

Comprehensive analysis of subtypes and risk model based on complement system associated genes in ccRCC

BACKGROUND

Immune therapy is widely used in treating clear cell renal cell carcinoma (ccRCC), yet identifying patient subgroups that are expected to response remains challenging. As complement system can mediate immune effects, including the progression of tumors, a correlation between complement system and immune therapy may exist.

METHODS

Based on 11 complement system associated genes (CSAGs) identified from The Cancer Genome Atlas (TCGA), we performed unsupervised clustering and classified the tumors into two different complement system (CS) patterns. The clinical significance, tumor microenvironment (TME), functional enrichment, and immune infiltration were further analyzed. A novel scoring system named CSscore was developed based on the expression levels of the 11 CSAGs.

RESULTS

Two distinct CS patterns were identified, classified as Cluster1 and Cluster2, and Cluster1 showed poor clinical outcome. Further analysis of functional enrichment, immune cell infiltration, and genetic variation revealed that Cluster1 had high infiltration of TME immune cells, but also exhibited high immune escape. The novel prognostic model, CSscore could act as an independent prognostic factor and effectively predict patients' prognosis and distinguish the therapeutic efficacy of different immune treatment strategies. The pan-cancer analysis of the CSscore indicates its potential to be further generalized to other types of cancer.

CONCLUSIONS

Two distinct CS patterns were identified and were further analyzed in terms of infiltration of TME immune cells and immune escape, providing potential explanations for the impact on prognosis of ccRCC. Our CSscore prognostic model may offer a novel perspective in the management of ccRCC patients, and potentially other types of cancer as well.

Exploring the Functional Basis of Epigenetic Aging in Relation to Body Fat Phenotypes in the Norfolk Island Cohort

DNA methylation is an epigenetic factor that is modifiable and can change over a lifespan. While many studies have identified methylation sites (CpGs) related to aging, the relationship of these to gene function and age-related disease phenotypes remains unclear. This research explores this question by testing for the conjoint association of age-related CpGs with gene expression and the relation of these to body fat phenotypes. The study included blood-based gene transcripts and intragenic CpG methylation data from Illumina 450 K arrays in 74 healthy adults from the Norfolk Island population. First, a series of regression analyses were performed to detect associations between gene transcript level and intragenic CpGs and their conjoint relationship with age. Second, we explored how these age-related expression CpGs (eCpGs) correlated with obesity-related phenotypes, including body fat percentage, body mass index, and waist-to-hip ratio. We identified 35 age-related eCpGs associated with age. Of these, ten eCpGs were associated with at least one body fat phenotype. Collagen Type XI Alpha 2 Chain (COL11A2), Complement C1s (C1s), and four and a half LIM domains 2 (FHL2) genes were among the most significant genes with multiple eCpGs associated with both age and multiple body fat phenotypes. The COL11A2 gene contributes to the correct assembly of the extracellular matrix in maintaining the healthy structural arrangement of various components, with the C1s gene part of complement systems functioning in inflammation. Moreover, FHL2 expression was upregulated under hypermethylation in both blood and adipose tissue with aging. These results suggest new targets for future studies and require further validation to confirm the specific function of these genes on body fat regulation.

Complement in Human Brain Health: Potential of Dietary Food in Relation to Neurodegenerative Diseases

The complement pathway is a major component of the innate immune system, which is critical for recognizing and clearing pathogens that rapidly react to defend the body against external pathogens. Many components of this pathway are expressed throughout the brain and play a beneficial role in synaptic pruning in the developing central nervous system (CNS). However, excessive complement-mediated synaptic pruning in the aging or injured brain may play a contributing role in a wide range of neurodegenerative diseases. Complement Component 1q (C1q), an initiating recognition molecule of the classical complement pathway, can interact with a variety of ligands and perform a range of functions in physiological and pathophysiological conditions of the CNS. This review considers the function and immunomodulatory mechanisms of C1q; the emerging role of C1q on synaptic pruning in developing, aging, or pathological CNS; the relevance of C1q; the complement pathway to neurodegenerative diseases; and, finally, it summarizes the foods with beneficial effects in neurodegenerative diseases via C1q and complement pathway and highlights the need for further research to clarify these roles. This paper aims to provide references for the subsequent study of food functions related to C1q, complement, neurodegenerative diseases, and human health.

A nanobody-based complement inhibitor targeting complement component 2 reduces hemolysis in a complement humanized mouse model of autoimmune hemolytic anemia

C2 is an attractive therapeutic target for many complement-mediated diseases. We developed Nab1B10, a new anti-C2 nanobody that potently and selectively inhibits both the classical and lectin pathways of complement activation. Mechanistically, Nab1B10 binds to the C2a portion of C2 and inhibits the assembly of C3 convertase C4b2a. Nab1B10 cross-reacts with monkey but not rodent C2 and inhibits classical pathway-mediated hemolysis. Using a new complement humanized mouse model of autoimmune hemolytic anemia (AIHA), we demonstrated that Nab1B10 abolished classical pathway complement activation-mediated hemolysis in vivo. We also developed C2-neutralizing bi- and tetra-valent antibodies based on Nab1B10 and found these antibodies significantly more potent than the other anti-C2 monoclonal antibody that is already in clinical trials. These data suggest that these novel C2-neutralizing nanobodies could be further developed as new therapeutics for many complement-mediated diseases, in which pathogenesis is dependent on the classical and/or lectin pathway of complement activation.

HMGB1 cleavage by complement C1s and its potent anti-inflammatory product

Complement C1s association with the pathogenesis of several diseases cannot be simply explained only by considering its main role in activating the classical complement pathway. This suggests that non-canonical functions are to be deciphered for this protease. Here the focus is on C1s cleavage of HMGB1 as an auxiliary target. HMGB1 is a chromatin non-histone nuclear protein, which exerts in fact multiple functions depending on its location and its post-translational modifications. In the extracellular compartment, HMGB1 can amplify immune and inflammatory responses to danger associated molecular patterns, in health and disease. Among possible regulatory mechanisms, proteolytic processing could be highly relevant for HMGB1 functional modulation. The unique properties of HMGB1 cleavage by C1s are analyzed in details. For example, C1s cannot cleave the HMGB1 A-box fragment, which has been described in the literature as an inhibitor/antagonist of HMGB1. By mass spectrometry, C1s cleavage was experimentally identified to occur after lysine on position 65, 128 and 172 in HMGB1. Compared to previously identified C1s cleavage sites, the ones identified here are uncommon, and their analysis suggests that local conformational changes are required before cleavage at certain positions. This is in line with the observation that HMGB1 cleavage by C1s is far slower when compared to human neutrophil elastase. Recombinant expression of cleavage fragments and site-directed mutagenesis were used to confirm these results and to explore how the output of C1s cleavage on HMGB1 is finely modulated by the molecular environment. Furthermore, knowing the antagonist effect of the isolated recombinant A-box subdomain in several pathophysiological contexts, we wondered if C1s cleavage could generate natural antagonist fragments. As a functional readout, IL-6 secretion following moderate LPS activation of RAW264.7 macrophage was investigated, using LPS alone or in complex with HMGB1 or some recombinant fragments. This study revealed that a N-terminal fragment released by C1s cleavage bears stronger antagonist properties as compared to the A-box, which was not expected. We discuss how this fragment could provide a potent brake for the inflammatory process, opening the way to dampen inflammation.

Integrated analysis to identify the prognostic and immunotherapeutic roles of coagulation-associated gene signature in clear cell renal cell carcinoma

The coagulation system is closely related to the physiological status and immune response of the body. Recent years, studies focusing on the association between coagulation system abnormalities and tumor progression have been widely reported. In clear cell renal cell carcinoma (ccRCC), poor prognosis often occurs in patients with venous tumor thrombosis and coagulation system abnormalities, and there is a lack of research in related fields. Significant differences in coagulation function were also demonstrated in our clinical sample of patients with high ccRCC stage or grade. Therefore, in this study, we analyzed the biological functions of coagulation-related genes (CRGs) in ccRCC patients using single-cell sequencing and TCGA data to establish the 5-CRGs based diagnostic signature and predictive signature for ccRCC. Univariate and multivariate Cox analyses suggested that prognostic signature could be an independent risk factor. Meanwhile, we applied CRGs for consistent clustering of ccRCC patients, and the two classes showed significant survival and genotype differences. The differences in individualized treatment between the two different subtypes were revealed by pathway enrichment analysis and immune cell infiltration analysis. In summary, we present the first systematic analysis of the significance of CRGs in the diagnosis, prognosis, and individualized treatment of ccRCC patients.

Degradation of collagen I by activated C1s in periodontal Ehlers-Danlos Syndrome

Periodontal Ehlers-Danlos syndrome (pEDS) is an autosomal dominant disorder characterized by early-onset periodontitis leading to premature loss of teeth, lack of attached gingiva and thin and fragile gums leading to gingival recession. Connective tissue abnormalities of pEDS typically include easy bruising, pretibial plaques, distal joint hypermobility, hoarse voice, and less commonly manifestations such as organ or vessel rupture. pEDS is caused by heterozygous missense mutations in C1R and C1S genes of the classical complement C1 complex. Previously we showed that pEDS pathogenic variants trigger intracellular activation of C1r and/or C1s, leading to extracellular presence of activated C1s. However, the molecular link relating activated C1r and C1s proteases to the dysregulated connective tissue homeostasis in pEDS is unknown. Using cell- and molecular-biological assays, we identified activated C1s (aC1s) as an enzyme which degrades collagen I in cell culture and in in vitro assays. Matrix collagen turnover in cell culture was assessed using labelled hybridizing peptides, which revealed fast and comprehensive collagen protein remodeling in patient fibroblasts. Furthermore, collagen I was completely degraded by aC1s when assays were performed at 40°C, indicating that even moderate elevated temperature has a tremendous impact on collagen I integrity. This high turnover is expected to interfere with the formation of a stable ECM and result in tissues with loose compaction a hallmark of the EDS phenotype. Our results indicate that pathogenesis in pEDS is not solely mediated by activation of the complement cascade but by inadequate C1s-mediated degradation of matrix proteins, confirming pEDS as a primary connective tissue disorder.

Quantitative fluorescence resonance energy transfer-based immunoassay for activated complement C1s

Objectives

C1s activation is associated with the pathogenesis of various diseases, indicating the potential value of C1s activation detection in clinic. Here we aimed to establish fluorescence resonance energy transfer (FRET)-based immunoassay for the quantitative detection of activated C1s in serum.

Methods

FRET-based fluorogenic peptides, sensitive to the enzymatic activity of activated C1s, were prepared and labeled with the fluorophore ortho-aminobenzoic acid (Abz) and quencher 2,4-dinitrophenyl (Dnp), and then were further selected depending on its Kcat/Km value. C1s in the samples was captured and separated using anti-C1s-conjugated magnetic microbeads. Next, enzymatic activity of activated C1s in samples and standards was examined using fluorescent quenched substrate assays. Limit of detection (LOD), accuracy, precision, and specificity of FRET-based immunoassay were also investigated.

Results

This method presented a linear quantification range for the enzymatic activity of activated C1s up to 10 μmol min^-1 mL^-1 and LOD of 0.096 μmol·min^-1·mL^-1 for serum samples. The recovery of the method was in the range of 90% ~ 110%. All CV values of the intra-analysis and inter-analysis of three levels in samples were less than 10%. The cross-reaction rates with C1r enzyme, MASP1, and MASP2 were less than 0.5%. No significant interferences were found with bilirubin (0.2 mg mL^-1), Chyle (2000 FTU), and haemoglobin (5 mg mL^-1), but anticoagulants (EDTA, citrate and heparin) inhibited the enzymatic ability of activated C1s. Thus, this established method can be used for the determination of active C1s in human serum samples in the concentration interval of 0.096-10.000 μmol min^-1 mL^-1.

Conclusions

One anti-C1s-based FRET immunoassay for activated C1s detection in serum samples were established, and it will be useful to explore the role of C1s activation in the pathogenesis, diagnosis and treatment in complement-related diseases.

Comprehensive Analysis of lncRNA and mRNA Expression Profile of Macrophage RAW264.7 Stimulated by Antimicrobial Peptide BSN-37

BACKGROUND

BSN-37, a novel antimicrobial peptide (AMP) containing 37 amino acid residues isolated from the bovine spleen, has not only antibacterial activity but also immunomodulatory activity. Recent evidence shows that long non-coding RNAs (lncRNAs) play an important role in regulating the activation and function of immune cells. The purpose of this experiment was to investigate the lncRNA and mRNA expression profile of mouse macrophages RAW264.7 stimulated by bovine antimicrobial peptide BSN-37.

METHODS

The whole gene expression microarray was used to detect the differentially expressed lncRNA and mRNA between antimicrobial peptide BSN-37 activated RAW264.7 cells and normal RAW264.7 cells. KEGG pathway analysis and GO function annotation analysis of differentially expressed lncRNAs and mRNA were carried out. Eight kinds of lncRNAs and nine kinds of mRNA with large differences were selected for qRT-PCR verification, respectively.

RESULTS

In the current study, we found that 1294 lncRNAs and 260 mRNAs were differentially expressed between antibacterial peptide BSN-37 treatment and control groups. Among them, Bcl2l12, Rab44, C1s, Cd101 and other genes were associated with immune responses and were all significantly up-regulated. Mest and Prkcz are related to cell growth, and other genes are related to glucose metabolism and lipid metabolism. In addition, some immune-related terms were also found in the GO and KEGG analyses. At the same time, real-time quantitative PCR was used to verify selected lncRNA and mRNA with differential expression. The results of qRT-PCR verification were consistent with the sequencing results, indicating that our data were reliable.

CONCLUSION

This study provides the lncRNA and mRNA expression profiles of RAW264.7 macrophages stimulated by antimicrobial peptide BSN-37 and helps to provide a reference value for subsequent studies on lncRNA regulation of antimicrobial peptide BSN-37 immune function.