Complement Cascade Research Articles

The Plasma Proteome and Risk of Future Venous Thromboembolism-Results from the HUNT Study.

This study aimed to identify novel plasma proteins associated with first-lifetime venous thromboembolism (VTE) and molecular pathways involved in VTE pathogenesis. A case-cohort comprising incident VTE cases (n = 294) and a randomly sampled age- and sex-weighted subcohort (n = 1,066) was derived from the Trøndelag Health Study (HUNT3, n = 50,800). Blood samples were collected and stored at cohort inclusion (2006-2008), and participants were followed up to 5 years. Proteome-wide analyses was performed using the 7k SomaScan® proteomics platform, and weighted Cox-regression models adjusted for age, sex, and sample batch were conducted, with the Bonferroni method applied to account for multiple testing. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were applied on the top-ranked 200 proteins associated with VTE. Out of 7,288 human proteins, 7 proteins were significantly associated with higher VTE risk with p-value <6.9 × 10-6 (hazard ratios per 1 standard deviation increase in protein levels ranging from 1.39 to 1.86). Except for coagulation factor VIII and tumor necrosis factor soluble receptor II, these proteins were novel associations and included collagen alpha-3(VI):BPTI/Kunitz inhibitor, histo-blood group ABO system transferase, peroxidasin, human epididymis protein 4, and regulator of G protein signaling 3. KEGG analyses of the top-ranked 200 proteins revealed significant pathway enrichment of nine proteins in the complement (mainly lectin pathway) and coagulation (mainly intrinsic pathway) cascades. Our proteome-wide analysis led to discovery of five novel protein candidates associated with 5-year risk of future VTE. KEGG analyses supported an interplay between the complement and coagulation pathways in the pathogenesis of VTE.

Complement activation drives the phagocytosis of necrotic cell debris and resolution of liver injury

Cells die by necrosis due to excessive chemical or thermal stress, leading to plasma membrane rupture, release of intracellular components and severe inflammation. The clearance of necrotic cell debris is crucial for tissue recovery and injury resolution, however, the underlying mechanisms are still poorly understood, especially in vivo. This study examined the role of complement proteins in promoting clearance of necrotic cell debris by leukocytes and their influence on liver regeneration. We found that independently of the type of necrotic liver injury, either acetaminophen (APAP) overdose or thermal injury, complement proteins C1q and (i)C3b were deposited specifically on necrotic lesions via the activation of the classical pathway. Importantly, C3 deficiency led to a significant accumulation of necrotic debris and impairment of liver recovery in mice, which was attributed to decreased phagocytosis of debris by recruited neutrophils in vivo. Monocytes and macrophages also took part in debris clearance, although the necessity of C3 and CD11b was dependent on the specific type of necrotic liver injury. Using human neutrophils, we showed that absence of C3 or C1q caused a reduction in the volume of necrotic debris that is phagocytosed, indicating that complement promotes effective debris uptake in mice and humans. Moreover, internalization of opsonized debris induced the expression of pro-resolving genes in a C3-dependent manner, supporting the notion that debris clearance favors the resolution of inflammation. In summary, complement activation at injury sites is a pivotal event for necrotic debris clearance by phagocytes and determinant for efficient recovery from tissue injury.

Paclitaxel-induced Hypersensitivity Reaction

Abstract An immunological response that results in an adverse reaction due to a certain drug is known as a hypersensitivity reaction (HSR). Such type of reactions is seen with antineoplastic agents. HSR is commonly seen with one of the chemotherapeutic agents, namely, paclitaxel. Occurrence of such reactions can be suppressed with the administration of premedications (dexamethasone 20 mg intravenous [IV], diphenhydramine 50 mg IV, and famotidine 20 mg IV). Mainly, the paclitaxel consists of paclitaxel IP, polyoxyl 35, castor oil IP (Cremophor ELP), and dehydrated alcohol IP. The mechanism of this reaction is not known exactly, but it is believed that the reaction may be occurring due to paclitaxel itself or its vehicle castor oil IP (Cremophor ELP). Molecules present in Cremophor ELP are found to be similar in structure to certain nonionic block copolymers that activate complement proteins (the proteins involved in various immune processes).

Astrocytes contribute to toll-like receptor 2-mediated neurodegeneration and alpha-synuclein pathology in a human midbrain Parkinson’s model

BackgroundParkinson’s disease (PD) is characterised by degeneration of ventral midbrain dopaminergic (DA) neurons and abnormal deposition of α-synuclein (α-syn) in neurons. Activation of the innate immune pathogen recognition receptor toll-like receptor 2 (TLR2) is associated with exacerbation of α-syn pathology. TLR2 is increased on neurons in the PD brain, and its activation results in the accumulation and propagation of α-syn through autophagy inhibition in neurons. In addition to the aggregation and propagation of pathological α-syn, dysfunction of astrocytes may contribute to DA neuronal death and subsequent clinical progression of PD. However, the role of astrocytes in TLR2-mediated PD pathology is less explored but important to address, given that TLR2 is a potential therapeutic target for PD.MethodsInduced pluripotent stem cells from three controls and three PD patients were differentiated into a midbrain model comprised of neurons (including DA neurons) and astrocytes. Cells were treated with or without the TLR2 agonist Pam3CSK4, and α-syn pathology was seeded using pre-formed fibrils. Confocal imaging was used to assess lysosomal function and α-syn pathology in the different cell types, as well as DA neuron health and astrocyte activation.ResultsTLR2 activation acutely impaired the autophagy lysosomal pathway, and potentiated α-syn pathology seeded by pre-formed fibrils in PD neurons and astrocytes, leading to degeneration and loss of DA neurons. The astrocytes displayed impaired chaperone-mediated autophagy reducing their ability to clear accumulated α-syn, and increases of A1 neurotoxic phenotypic proteins SerpinG1, complement C3, PSMB8 and GBP2. Moreover, the phenotypic changes in astrocytes correlated with a specific loss of DA neurons.ConclusionsTaken together, these results support a role for astrocyte dysfunction in α-syn accumulation and DA neuronal loss following TLR2 activation in PD.

Integrated analysis of proteome and transcriptome revealed changes in multiple signaling pathways involved in immunity in the northern snakehead (Channa argus) during Nocardia seriolae infection

The northern snakehead (Channa argus) is a valuable aquaculture species across certain Asian countries, contributing significantly to economic prosperity and dietary needs. However, its productivity faces significant challenges, particularly from diseases such as nocardiosis, caused by Nocardia seriolae. To date, the majority of research efforts have focused on describing the observed phenomena related to N. seriolae infection. However, there remains a notable gap in knowledge concerning the infectivity of N. seriolae and the immune response it elicits. To better understand the modulation of the immune responses to N. seriolae infection in snakeheads, we investigated the splenic proteome profiles. Specifically, we compared the profiles between uninfected northern snakehead specimens and those infected with N. seriolae at 96 h using the label-free data-independent acquisition methodology. A total of 700 differentially expressed proteins (DEPs) were obtained. Of these, 353 proteins exhibited upregulation, whereas 347 proteins displayed downregulation after the infection. The DEPs were mapped to the reference canonical pathways in Kyoto Encyclopedia of Genes and Genomes database, revealing several crucial pathways that were activated following N. seriolae infection. Noteworthy, among these were pathways such as ferroptosis, complement and coagulation cascades, chemokine signaling, tuberculosis, natural killer cell-mediated cytotoxicity, and Th17 cell differentiation. Furthermore, protein–protein interaction networks were constructed to elucidate the interplay between immune-related DEPs. These results revealed expression changes in multiple signaling pathways during the initial colonization phase of N. seriolae. This discovery offers novel insights into the infection mechanisms and host interaction dynamics associated with N. seriolae.

Long-term dysregulation of plasma peptidome in mild and multiple COVID-19 recovered patients revealed by a novel efficient peptidomics workflow.

After recovering from COVID-19, many patients experience "long COVID" symptoms. Existing research has predominantly focused on moderate to severe cases, with limited studies examining mild cases and recurrent infections. The circulating low-molecular-weight (LMW) peptidome, involving lipid metabolism, coagulation, and immune pathways, is crucial for understanding COVID-19's long-term effects. We developed a peptidomics workflow utilizing solid-phase extraction with highly wrinkled GO-Fe3O4 composite materials (HWGO-F) and nanoLC-MS/MS detection. By altering the pH, HWGO-F enhances plasma peptide adsorption and purification. Compared to traditional methods, our workflow offers improved detection depth and reproducibility for over 70% of peptide signals with CV < 20%. We investigated plasma peptide profiles in mild COVID-19 patients post-recovery from single or second infections. The findings indicate persistent abnormalities in initial COVID-19 infections' plasma peptide profiles, gradually diminishing over time. Secondary infections prolong recovery. Disrupted functions include lipid metabolism, coagulation and complement cascades, and infection-related pathways. Lipid metabolism may normalize within 3 months, while coagulation and immune abnormalities can last 3-6 months. After secondary infections, lipid metabolism irregularities may last at least 1 month, with extended coagulation and immune imbalances. These results provide a theoretical foundation for understanding the widespread occurrence of long COVID and guide recovery care for mild cases.

The Complement System– An Important New Therapeutic Target in IgA Nephropathy

Background: IgA nephropathy is the most common primary glomerular disease worldwide. Until recently, there were not any treatments of proven benefit, and care of patients with IgAN primarily involved supportive measures. Within the past few years, however, multiple new drugs have shown promise in clinical trials. Summary: Several complement inhibitory drugs have demonstrated efficacy at reducing proteinuria, and there is a strong rationale for expecting that these agents will be effective at slowing progression of the disease. Furthermore, anti-complement drugs target a part of the immune system that is not directly blocked by other classes of immunosuppressive agents. One of the new drugs, iptacopan, is a selective inhibitor of the alternative pathway. Preliminary results from a phase 3 study of iptacopan in IgA nephropathy demonstrated that treatment is associated with a rapid reduction in proteinuria, and the drug recently received accelerated approved from the Food and Drug Administration. Additional drugs that have been tested in IgA nephropathy include agents that block the complement cascade at the levels of C3 and C5. Complement activation in the kidneys of IgA nephropathy patients generates biomarkers that can be detected in the blood, urine, and kidney biopsies. If multiple complement inhibitory drugs receive approval for IgA nephropathy, these biomarkers may be useful for selecting the most appropriate drug for an individual patient. Complement biomarkers may also be useful for monitoring a patient’s response to treatment. Key Messages: Several complement inhibitors are currently in clinical trials for IgAN. Iptacopan recently received accelerated approval for the indication and complement inhibitory drugs will likely become an integral part of the treatment for this disease in the near future. As these drugs become available in the clinic, it will be important to develop biomarkers that can guide clinicians to the best drug for an individual patient.

A Comprehensive Proteomic and Bioinformatic Analysis of Human Spinal Cord Injury Plasma Identifies Proteins Associated with the Complement Cascade and Liver Function as Potential Prognostic Indicators of Neurological Outcome.

Spinal cord injury (SCI) is a major cause of disability, with complications postinjury often leading to lifelong health issues with the need for extensive treatment. Neurological outcome post-SCI can be variable and difficult to predict, particularly in incompletely injured patients. The identification of specific SCI biomarkers in blood may be able to improve prognostics in the field. This study has utilized proteomic and bioinformatic methodologies to investigate differentially expressed proteins in plasma samples across human SCI cohorts with the aim of identifying candidate prognostic biomarkers and biological pathway alterations that relate to neurological outcome. Blood samples were taken, following informed consent, from American Spinal Injury Association impairment scale (AIS) grade C "improvers" (those who experienced an AIS grade improvement) and "nonimprovers" (no AIS change) and AIS grade A and D at <2 weeks ("acute") and ∼3 months ("subacute") postinjury. The total protein concentration from each sample was extracted, with pooled samples being labeled and nonpooled samples treated with ProteoMiner™ beads. Samples were then analyzed using two 4-plex isobaric tag for relative and absolute quantification (iTRAQ) analyses and a label-free experiment for comparison before quantifying with mass spectrometry. Data are available via ProteomeXchange with identifiers PXD035025 and PXD035072 for the iTRAQ and label-free experiments, respectively. Proteomic datasets were analyzed using OpenMS (version 2.6.0). R (version 4.1.4) and, in particular, the R packages MSstats (version 4.0.1) and pathview (version 1.32.0) were used for downstream analysis. Proteins of interest identified from this analysis were further validated by enzyme-linked immunosorbent assay. The data demonstrated proteomic differences between the cohorts, with the results from the iTRAQ approach supporting those of the label-free analysis. A total of 79 and 87 differentially abundant proteins across AIS and longitudinal groups were identified from the iTRAQ and label-free analyses, respectively. Alpha-2-macroglobulin, retinol-binding protein 4 (RBP4), serum amyloid A1, peroxiredoxin 2 (PRX-2), apolipoprotein A1, and several immunoglobulins were identified as biologically relevant and differentially abundant, with potential as individual candidate prognostic biomarkers of neurological outcome. Bioinformatics analyses revealed that the majority of differentially abundant proteins were components of the complement cascade and most interacted directly with the liver. Many of the proteins of interest identified using proteomics were detected only in a single group and therefore have potential as binary (present or absent) biomarkers, RBP4 and PRX-2 in particular. Additional investigations into the chronology of these proteins and their levels in other tissues (cerebrospinal fluid in particular) are needed to better understand the underlying pathophysiology, including any potentially modifiable targets. Pathway analysis highlighted the complement cascade as being significant across groups of differential functional recovery.

The effect of taraxerol acetate extracted from dandelion on alleviating oxidative stress responses in vitro

Oxidative stress can be alleviated by antioxidants intakes. Taraxerol acetate (TA), a natural triterpenoid extracted from dandelions, may reduce the risk of metabolic disorders by regulating oxidative stress. In the study, we investigated the effects of TA in relieving oxidative stress in murine intestinal epithelial cells using multiomics techniques. Here, we found that TA activated the antioxidant defense system. Total antioxidant capacity (T-AOC) and Catalase (CAT) activity notably increased after TA treatment. Additionally, TA treatment effectively reduced the levels of lactate dehydrogenase (LDH) and malonaldehyde (MDA) and alleviated H2O2-induced oxidative stress. Furthermore, TA induced significant changes in the levels of 30 important metabolites. Specifically, it activated the complement and coagulation cascades, NF-κB and MAPK and glycerophospholipid pathways, resulting in altered transcript levels of related genes, such as Serpinb9e, SCD2, Hspa1b, and Hspa1a. Thus, the results demonstrated that TA potentially could promote health by alleviating H2O2-induced oxidative damage and provide valuable insights for its further development.

Epigenetic regulation of complement C1Q gene expression.

Human C1q is a multifaceted complement protein whose functions range from activating the complement classical pathway to immunomodulation and promoting placental development and tumorigenesis. It is encoded by the C1QA, C1QB, and C1QC genes located on chromosome 1. C1q, unlike most complement components, has extrahepatic expression by a range of cells including macrophages, monocytes and immature dendritic cells. Its local synthesis under the conditions of inflammation and for the purpose of removal of altered self requires its strict transcriptional regulation. To delve into C1Q transcriptional regulation and unravel potential epigenetic influences, we conducted an in silico analysis utilizing a range of online tools and datasets. Co-expression analysis revealed tight coordination between C1QA, C1QB, and C1QC genes. Strikingly, distinct epigenetic patterns emerged across various cell types expressing or lacking these genes, with unique histone marks and DNA methylation status characterizing their regulatory landscape. Notably, the investigation extended to tumor contexts, unveiled potential epigenetic roles in malignancies. The cell type and tumor-specific histone modifications and chromatin accessibility patterns underscore the dynamic nature of epigenetic regulation of C1Q, providing crucial insights into the intricate mechanisms governing the expression of these immunologically significant genes. The findings provide a foundation for future investigations into targeted epigenetic modulation, offering insights into potential therapeutic avenues for immune-related disorders and cancer mediated via C1q.

Impact of Microcystin-LR exposure on biochemical responses, transcriptomic profiles, gut microbiota, and growth performance in grass carp (Ctenopharyngodon idella)

In recent years, Microcystin-LR (MC-LR) has been frequently detected in aquatic environments, exerting detrimental effects on the health of aquatic organisms. The grass carp (Ctenopharyngodon idella), an economically important fish, inhabits environments prone to MC-LR contamination. To investigate the toxicological mechanisms of MC-LR on grass carp, the fish were exposed to water containing 35.8 μg/L MC-LR. The physiological, biochemical, gut microbiota, and transcriptomic responses of the grass carp were evaluated at various time points (days 0, 1, 3, 7, and 21). The results showed that total superoxide dismutase activity in the liver and intestine was significantly increased after 21 days of exposure. Additionally, pathological damage was observed, including impaired intestinal epithelial barrier and nuclear pyknosis in the liver cell. MC-LR exposure also altered the diversity and composition of the gut microbiota and reshaped the microbiota interaction network, increasing the abundance of Cetobacterium and Vibrio by 32.43% and 25.7%, respectively. The intestinal microbiota functions were enriched in carbohydrate metabolism (10.45%) and amino acid metabolism (9.89%). RNA sequencing identified 504 shared differentially expressed genes (DEGs). The expression of the immune genes ITGB1 and GART was significantly upregulated in the D21 group. The upregulated DEGs were enriched in the complement and coagulation cascade pathways. MC-LR exposure induced metabolic disorders in grass carp, with upregulated genes significantly enriched in amino acid and carbohydrate metabolism pathways, while downregulated genes were enriched in lipid metabolism. This study provides valuable insights into the effects and toxicological mechanisms of MC-LR on aquatic organisms.

Targeted Regulation of Osteoblasts and Osteoclasts in Osteosarcoma Patients by CSF3R Receptor Inhibition of Osteolysis Caused by Tumor Inflammation Based on Transcriptional Spectrum Analysis and Drug Library Screening.

Osteosarcoma (OS) is a common primary malignant bone tumor that mainly occurs in children and adolescents. The use of IL-8 inhibitor compounds has been reported in patents, which can be used to treat and/or prevent osteosarcoma, but the pathogenesis of osteosarcoma remains to be investigated. At present, osteoblasts and osteoclasts play an important role in the occurrence and development of OS. However, the relationship between osteoblasts and osteoclasts in the specific participation mechanism and inflammatory response of OS patients has not been further studied. The transcriptome, clinical data, and other data related to OS were downloaded from the GEO database to analyze them with 200 known inflammatory response genes. We set the screening conditions as p < 0.05 and | log2FC| > 0.50, screened the differentially expressed genes (DEGs) related to OS, tested the correlation coefficient between the OS INF gene and clinical risk, and analyzed the survival prognosis. We further enriched and analyzed the DEGs and inflammatory response genes of OS with GO/KEGG to explore the potential biological function and signal pathway mechanism of OS inflammatory response genes. Moreover, the virtual screening of drug sensitivity of OS based on the FDA drug library was also carried out to explore potential therapeutic drugs targeted to regulate OS osteogenesis and osteoclast inflammation, and finally, the molecular dynamics simulation verification of OS core protein and potential drugs was carried out to explore the binding stability and mechanism between potential drugs and core protein. Through differential analysis of GSE39058, GSE36001, GSE87624, and three other data sets closely related to OS osteoblasts and osteoclasts, we found that there was one upregulated gene (CADM1) and one down-regulated gene (PHF15) related to OS. In addition, GSEA enrichment analysis of the DEGs of OS showed that it was mainly involved in the progress of OS through biological functions, such as oxidative photosynthesis, acute junction, and epithelial-mesenchymal transition. The enrichment analysis of OS DEGs revealed that they mainly affect the occurrence and progress of OS by participating in the regulation of the actin skeleton, PI3K Akt signal pathway, complement and coagulation cascade. According to the expression of CSF3R in OS patients, a risk coefficient model and a diagnostic model were established. It was found that the more significant the difference in the CSF3R gene in OS patients, the greater the risk coefficient of disease (p < 0.05). The AUC under the curve of the CSF3R gene was greater than 0.65, which had a good diagnostic significance for OS. The above results showed that the prognosis risk gene CSF3R related to OS inflammation was closely related to the survival status of OS patients. Finally, through the virtual screening of the ZINC drug library and molecular dynamics simulation, it was found that the docking model formed by the core protein CSF3R and the compounds, Leucovorin and Methotrexate, were the most stable, which revealed that the compounds Leucovorin and Methotrexate might play a role in the treatment of OS by combining with the inflammatory response related factor CSF3R of OS. CSF3R participates in the occurrence and development of OS bone destruction by regulating the inflammatory response of osteoblasts and osteoclasts and can affect the survival prognosis of OS patients.

The Role of the Complement System in Autoimmune Diseases and Therapeutic Targeting

The complement system, a critical component of the innate immune system, plays a dual role in immune defense and pathogenesis, particularly in autoimmune diseases. Comprising over 30 proteins, the complement system facilitates pathogen clearance, inflammation, and immune modulation. However, its dysregulation can lead to uncontrolled activation and contribute to the development and progression of various autoimmune disorders, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), antiphospholipid syndrome (APS), and vasculitis. In these diseases, excessive complement activation triggers inflammation, immune cell recruitment, and tissue damage, exacerbating the autoimmune response. This review provides an in-depth analysis of the complement system’s role in autoimmune diseases, exploring how its three activation pathways—classical, lectin, and alternative—contribute to disease pathogenesis. It also discusses key complement proteins such as C3, C5, and the membrane attack complex (MAC) in promoting inflammatory responses in these conditions. Moreover, the review highlights recent advances in therapeutic strategies targeting the complement system, including the development of C5 inhibitors like eculizumab and C3 inhibitors, which show promise in treating complement-mediated autoimmune diseases. These therapies aim to reduce inflammation and tissue destruction, offering new approaches for managing autoimmune disorders. Understanding complement dysregulation is crucial for the development of more effective treatments in the future. Keywords: Complement system, Autoimmune diseases, Complement activation, Inflammation, Therapeutic targeting

Divergent changes in complement pathway gene expression in schizophrenia and bipolar disorder: Links to inflammation and neurogenesis in the subependymal zone

Deficits in neurogenesis markers in the subependymal zone (SEZ) are associated with elevated inflammation in schizophrenia and bipolar disorder. However, the extent to which complement factors are also changed in the SEZ of these major psychiatric disorders and their impact on neurogenesis remains poorly understood. We extracted RNA from the SEZ of 93 brains, including controls (n = 32), schizophrenia (n = 32), and bipolar disorder (n = 29) cases. Quantitative RT-PCR measured 13 complement transcripts encoding initiators, convertases, effectors or inhibitors. Differences in abundance were analysed by diagnosis and inflammatory subgroups (high- or low-inflammation), which were previously defined by SEZ cytokine and inflammation marker expression.Complement mRNAs C1QA (p = 0.011), C1QB (p < 0.001), C1R (p = 0.027), and Factor B (p = 0.025) were increased in high-inflammation schizophrenia versus low-inflammation controls. Conversely, high-inflammation bipolar cases had decreased C1QC (p = 0.011) and C3 (p = 0.003). Complement mRNAs C1R (SCZ, p = 0.010; BD, p = 0.047), C1S (SCZ, p = 0.026; BD, p = 0.017), and Factor B (BD, p = 0.025) were decreased in low-inflammation schizophrenia and bipolar subgroups versus low-inflammation controls. Complement inhibitors varied by subgroup: Factor H was increased in high-inflammation schizophrenia (p < 0.001), and CD59 in high-inflammation bipolar disorder (p = 0.020). Complement activator and inhibitor mRNAs were positively correlated with quiescent neural stem cell marker GFAPD (q < 0.05) but negatively with immature neuron markers DLX6-AS1 (q < 0.05) and DCX (q < 0.05).These findings suggest altered complement cascade expression in the SEZ in high- and low-inflammation schizophrenia and bipolar disorder, with opposite directional changes suggesting distinct molecular pathology. Complement activation may promote stem cell quiescence and reduce differentiation or survival of newborn neurons.

Comprehensive transcriptomic, proteomic, and intestinal microbiota analyses of largemouth bass (Micropterus salmoides) intestines reveal new insights into immune responses to Aeromonas hydrophila infection

This study investigates the immune responses of largemouth bass (Micropterus salmoides) to infection by Aeromonas hydrophila, a pathogen responsible for significant economic losses in freshwater aquaculture due to bacterial enteritis. We employed transcriptomic sequencing, label-free LC-MS/MS quantitative proteomics, and 16S RNA sequencing to evaluate the transcriptomic, proteomic, and intestinal microbiota changes in infected fish compared to healthycontrols. Each fish (approximately 60 g) in the infection group was injected with 0.5 ml of an A. hydrophila suspension (1.0 × 108 CFU/mL), while the control group received 0.5 ml of phosphate buffer. Samples were collected 72 h post-injection, with three biological replicates made from an equal mix of tissue samples from six fish each. A total of 1666 differentially expressed genes (DEGs) and 2477 differentially expressed proteins (DEPs) were identified. Integrated analysis revealed that the up-regulated DEGs/DEPs in the intestines of infected largemouth bass were primarily associated with immune-related pathways including "antigen processing and presentation", "MAPK signaling pathway", "ECM-receptor interaction", and "leukocyte transendothelial migration". Notable upregulated immune-related proteins included complement or antigen-presenting proteins like complement C1, complement C3, complement C6, ɑ-2-macroglobulin, laminin, serotransferrin, leukocyte cell-derived chemotaxin-2, immunoglobulin C1-set domain-containing protein, and the MHC class I alpha antigen. 16S RNA sequencing indicated a significant increase in Proteobacteria and a decrease in Fusobacteria in the intestines of infected fish compared to controls. Collectively, these findings demonstrate that A. hydrophila infection significantly alters gene and protein expression as well as intestinal microbiota in largemouth bass, providing insights into their immune defense mechanisms against infection.

Transcriptomic and proteomic analysis of the jejunum revealed the effects and mechanism of protocatechuic acid on alleviating Salmonella typhimurium infection in chickens

Salmonella typhimurium is a common cause of gastroenteritis, which infects animals and human. Protocatechuic acid has anti-inflammatory, immunoregulatory and anti-pathogenic effects, and is expected to be an effective choice for alleviating Salmonella infection and intestinal injury. A total of 180 1-d female, yellow-feathered chickens were randomly allocated into 3 treatment groups, the controls (Ctr), the Salmonella-challenged treatment (Sal) and the protocatechuic acid treatment (PA). Birds were fed a basal diet for 18 d, with birds in PA supplemented with 600 mg/kg protocatechuic acid. On 14 and 16 d, birds in Sal and PA were orally challenged with 109 CFU S. typhimurium, while birds in Ctr received an equal amount of PBS. The results showed that protocatechuic acid improved growth performance and jejunal structure in Salmonella-infected chickens (P < 0.05). In addition, protocatechuic acid suppressed (P < 0.05) the secretion of plasmal IgG, IL-1β, and IFN-β, and jejunal mucosal IL-6, IFN-β, complement protein 3 and 4. Mechanistically, the transcriptomic results showed that dietary protocatechuic acid inhibited acute inflammatory response and activated the signaling pathways of cytokine-cytokine receptor interaction, complement and coagulation cascades. Results of proteomic showed that protocatechuic acid inhibited the positive regulation of dendritic cell cytokine production and I-κB kinase/NF-κB signaling, as well as cytokine-cytokine receptor interaction and MAPK signaling pathways, and activated the mTOR signaling pathways. These results were critical to both suppressing the secretion of inflammatory cytokines and restoring the intestinal function. Dietary protocatechuic acid (600 mg/kg) was effective to alleviate Salmonella infection, as it suppressed the levels of cytokines and complement protein by inhibiting MAPK, I-κB kinase/NF-κB and enhancing the mTOR signaling pathway, thus offset the decline in weight loss and intestinal injury caused by infection.

Identification of Novel Proteins Mediating Causal Association Between Smoking and Essential Hypertension: A Mendelian Randomization Study.

Smoking is a factor for hypertension. We aim to reveal novel plasma proteins mediating the relationship of smoking with hypertension and identify potential drug targets for hypertension on the basis of Mendelian randomization design. Data for smoking were selected from the largest genome-wide association study meta-analysis performed by the Genome-Wide Association Study and Sequencing Consortium of Alcohol and Nicotine Use. Data for plasma proteins were selected from the deCODE Health study and the UK Biobank Pharma Proteomics Project. Data for hypertension were extracted from the FinnGen Study. Moreover, proteome-wide Mendelian randomization and colocalization analyses, 2-step Mendelian randomization, and gene function and network prediction, as well as druggability assessment were performed. We finally identified 8 proteins (ANXA4 [annexin A4], DLK1 [protein delta homolog 1], KLB [β-klotho], MMP8 [matrix metallopeptidase 8], PLAT [tissue-type plasminogen activator], POSTN [periostin], SAT2 [thialysine N-ε-acetyltransferase], and IFNLR1 [interferon λ receptor 1]) mediating association of smoking with hypertension. PLAT and IFNLR1 were identified to be involved in the complement and coagulation cascades and the Janus kinase/signal transducer and activator of transcription signaling pathway. ANXA4, KLB, MMP8, PLAT, and IFNLR1 had druggability. Moreover, IFNLR1 had strong evidence of genetic colocalization, because the posterior probability for H4 of IFNLR1 was 91.3%. This study identified the 8 proteins that mediate causal association between smoking and essential hypertension. Interferon λ receptor agonist targeting IFNLR1 may open a new avenue for treating hypertension. Our discoveries provide new insights into protein pathogenesis of hypertension and to better guide hypertension prevention and treatment among smokers.

Adult Onset Foveomacular Vitelliform Dystrophy Shows Genetic Overlap With Age-Related Macular Degeneration.

Adult-onset foveomacular vitelliform dystrophy (AFVD) shares phenotypic similarities with age-related macular degeneration (AMD). The genetic factors associated with AFVD are unknown in >80% of cases. This study evaluated the association of known AMD genetic risk variants with AFVD and compared systemic complement activation in these conditions. Clinical, imaging, and genetic data were collected from 50 patients with AFVD (men/women = 25/25, mean age ± SD 73 ± 10 years), 917 patients with AMD (men/women = 377/540, mean age ± SD 77 ± 9 years), and 432 unaffected healthy controls (men/women = 202/230, mean age ± SD 71 ± 8 years). Genotyping focused on 52 single nucleotide polymorphisms (SNPs) linked to AMD. Weighted genetic risk scores (GRS) for 19 complement system associated variants, 7 lipid metabolism associated variants, the remaining 26 variants (other pathways GRS), and for all 52 variants (global score) were derived and correlated with phenotype. Of the 52 SNPs evaluated, CFH (rs570618) and C2/CFB/SKIV2L (rs116503776 and rs114254831) were associated with AFVD compared with healthy controls (odds ratio [OR] = 2.73, 95% confidence interval [CI] = 1.32-5.73, P = 0.01; OR = 0.31, 95% CI = 0.14-0.71, P = 0.0036; and OR = 0.41, 95% CI = 0.22-0.74, P = 0.0025, respectively). MIR6130/RORB (rs10781182) was negatively associated with AFVD compared with the healthy controls (OR = 0.13, CI = 0.06-0.25, P < 0.0001) and AMD (OR = 0.19, CI = 0.10-0.34, P < 0.0001). Regression analysis showed complement GRS was positively associated with AFVD compared with controls (OR = 1.42, 95% CI = 1.04-1.95, P = 0.03), whereas the other pathways' GRS was negatively associated (OR = 0.46, 95% CI = 0.21-0.98, P = 0.04). AMD was positively associated with the complement score, global score, and ARMS2/HTRA1 compared with controls. Non-monogenic AFVD is associated with AMD risk alleles in the complement cascade, but not in other pathways. Further research is needed to explore complement inhibition for AFVD.

Atypical hemolytic uremic syndrome: diagnosis, management, and discontinuation of therapy.

Atypical hemolytic uremic syndrome (aHUS) is a thrombotic microangiopathy typically characterized by anemia, thrombocytopenia, and end-organ injury. aHUS occurs due to endothelial injury resulting from overactivation of the alternative pathway of the complement system. The etiology of the dysregulated complement system is either a genetic mutation in 1 or more complement proteins or an acquired deficiency due to autoantibodies. Over the past decade, advancements in our understanding of the role of complement in the pathophysiology of aHUS as well as the availability of anticomplement drugs has been a game-changer for our patients. These drugs have revolutionized the clinical course, outcome, and prognosis of this disease. Therefore, all patients in whom aHUS is suspected should undergo testing for complement genetic variants and autoantibodies. In approximately 30% to 40% of patients, a genetic variant of uncertain significance (VUS) may be identified. Such patients should undergo further testing to define the significance of the VUS. A combination of antigenic, functional, and biomarker analyses can assist in establishing the significance of the variants and thereby define the etiology in most patients. These analyses will also help to determine the duration of treatment based on the individual's genetic alteration. This review aims to shed light on the diagnosis and management of aHUS and discusses how to stratify patients to determine who can safely discontinue anticomplement therapy.

Intraocular complement activation is independent of systemic complement activation and is related to macular vascular remodelling in retinal vein occlusion

BackgroundRetinal vein occlusion (RVO) is a major cause of vision loss. The pathogenesis remains poorly defined although inflammation is known to play a critical role. In this study, we investigated the levels of complement proteins in the aqueous humour and plasma of RVO participants and the relationship between complement levels and retinal pathologies.MethodsThe plasma and aqueous humour were collected from 20 treatment-naive RVO and 20 cataract patients. Retinal lesions were examined by fundus stereoscopy and optical coherence tomography angiography. The levels of C1q, C2, C4, C4b, C3, C3b/iC3b, C5, C5a, CFB, CFD, CFI, CFH, and MBL in the plasma and aqueous humour were measured using the Luminex® x MAP® multiplex assay.ResultsRVO patients had significantly higher levels of C4, C4b, C3b/iC3b, CFB, and CFH in the plasma and aqueous humour compared to controls. The aqueous levels of C1q, C2, C5, C5a, and MBL were also significantly higher in RVO patients than in controls. CRVO patients had higher intraocular levels of C1q, C4, C5, CFI, CFH, and MBL than BRVO patients. C5a was below the detectable limit in the plasma in 18 cataracts and 16 RVO participants. The intraocular levels of C5a positively correlated with C1q, C2, C4, C3, C5, CFB, CFH, and MBL. The intraocular levels of CFD, CFI and MBL positively correlated with CRT, and the levels of C2, C3, C5, CFB, and MBL negatively correlated with the size of the foveal avascular zone. The plasma levels of C4b, C3b/iC3b, and CFD positively correlated with their counterparts in the aqueous humour in cataracts but not in RVO patients. The ratios of aqueous humour/plasma of C1q, C4, C4b, C3b/iC3b, C5, CFB, CFD, CFI, and CFH in the RVO patients were significantly higher than those in the cataract patients.Discussion and conclusionsThe intraocular complement activation in RVO is mediated by the classical and the alternative pathways and is largely independent of systemic complement activation. Intraocular complement activation may be related to retinal oedema and vascular remodeling in RVO patients.