The first case report of complement component 7 deficiency in Qatar and a 10-year follow-up.

Introduction: Neisseria meningitidis is a significant cause of bacterial meningitis and septicemia worldwide. Recurrent Neisseria meningitidis is frequently associated with terminal complement protein deficiency, including Complement component 7. This report discusses the first case of C7 deficiency in Qatar. Case report: A 30-year-old Qatari man presented with a meningococcal infection, which was verified by a blood culture. He experienced two episodes of meningitis caused by an undetermined organism. His blood tests revealed low levels of CH50 and C7. His C7 gene testing revealed a homozygous mutation in exon 10 (c.1135G>C p.Gly379Arg), a mutation that has not been previously documented in Qatar. However, it has been observed in 1% of Moroccan-origin Israeli Jews who also exhibit C7 deficiency. Regular prophylactic quadrivalent vaccinations against types A, C, Y, and W-135 with azithromycin tabs were administered. Over the last 10 years of follow-up, he remained in good health, with no further meningitis episodes. Conclusion: To our knowledge, this is the first confirmed case of C7 deficiency reported in the Arabian Gulf countries. Such rare diseases should be a public health priority. Awareness among medical practitioners and the community should help with early detection of C7 deficiency and the prevention of its consequences.

Effects of salinity stress on methylation of the liver genome and complement gene in large yellow croaker (Larimichthys crocea).

Salinity is an important environmental factor that affects the yield and quality of large yellow croaker (Larimichthys crocea) during aquaculture. Here, whole-genome bisulfite sequencing (WGBS), RNA-seq, bisulfite sequencing PCR (BSP), quantitative real-time PCR (qPCR), and dual luciferase reporter gene detection technologies were used to analyze the DNA methylation characteristics and patterns of the liver genome, the expression and methylation levels of important immune genes in large yellow croaker in response to salinity stress. The results of WGBS showed that the cytosine methylation of CG type was dominant, CpGIsland and repeat regions were important regions where DNA methylation occurred, and the DNA methylation in upstream 2k (2000bp upstream of the promoter) and repeat regions had different changes in the liver tissue of large yellow croaker in the response to the 12‰, 24‰, 36‰ salinity stress of 4 w (weeks). In the combined analysis of WGBS and transcriptome, the complement and coagulation cascade pathways were significantly enriched, in which the complement-related genes C7, C3, C5, C4, C1R, MASP1, and CD59 were mainly changed in response to salinity stress. In the studied area of MASP1 gene promoter, the methylation levels of many CpG sites as well as total cytosine were strongly negatively correlated with mRNA expression level. Methylation function analysis of MASP1 promoter further proved that DNA methylation could inhibit the activity of MASP1 promoter, indicating that salinity may affect the expressions of complement-related genes by DNA methylation of gene promoter region.

Birth and death in terminal complement pathway.

The cytolytic activity of the membrane attack complex (MAC) is pivotal in the complement-mediated elimination of pathogens. Terminal complement pathway (TCP) genes encode the proteins that form the MAC. Although the TCP genes are well conserved within most vertebrate species, the early evolution of the TCP genes is poorly understood. Based on the comparative genomic analysis of the early evolutionary history of the TCP homologs, we evaluated four possible scenarios that could have given rise to the vertebrate TCP. Currently available genomic data support a scheme of complex sequential protein domain gains that may be responsible for the birth of the vertebrate C6 gene. The subsequent duplication and divergence of this vertebrate C6 gene formed the C7, C8α, C8ß, and C9 genes. Compared to the widespread conservation of TCP components within vertebrates, we discovered that C9 has disintegrated in the genomes of galliform birds. Publicly available genome and transcriptome sequencing datasets of chicken from Illumina short read, PacBio long read, and Optical mapping technologies support the validity of the genome assembly at the C9 locus. In this study, we have generated a > 120X coverage whole-genome Chromium 10x linked-read sequencing dataset for the chicken and used it to verify the loss of the C9 gene in the chicken. We find multiple CR1 (chicken repeat 1) element insertions within and near the remnant exons of C9 in several galliform bird genomes. The reconstructed chronology of events shows that the CR1 insertions occurred after C9 gene loss in an early galliform ancestor. Loss of C9 in galliform birds, in contrast to conservation in other vertebrates, may have implications for host-pathogen interactions. Our study of C6 gene birth in an early vertebrate ancestor and C9 gene death in galliform birds provides insights into the evolution of the TCP.

Comprehensive Update and Revision of Nomenclature on Complement C6 and C7 Variants.

Complement genes encompass a wide array of variants, giving rise to numerous protein isoforms that have often been shown to exhibit clinical significance. Given that these variants have been discovered over a span of 50 y, one challenging consequence is the inconsistency in the terminology used to classify them. This issue is prominently evident in the nomenclature used for complement C6 and C7 variants, for which we observed a great discrepancy between previously published works and variants described in current genome browsers. This report discusses the causes for the discrepancies in C6 and C7 nomenclature and seeks to establish a classification system that would unify existing and future variants. The inconsistency in the methods used to annotate amino acids and the modifications pinpointed in the C6 and C7 primers are some of the factors that contribute greatly to the discrepancy in the nomenclature. Several variants that were classified incorrectly are highlighted in this report, and we showcase first-hand how a unified classification system is important to match previous with current genetic information. Ultimately, we hope that the proposed classification system of nomenclature becomes an incentive for studies on complement variants and their physiological and/or pathological effects.

Functional genetic variants in complement component 7 confer susceptibility to gastric cancer.

BACKGROUND: Complement system plays an important role in innate immunity which involved in the changes tumor immune microenvironment by mediating the inflammatory response. This study aims to explore the relationship between complement component 7 (C7) polymorphisms and the risk of gastric cancer (GC). MATERIALS AND METHODS: All selected SNPs of C7 were genotyped in 471 patients and 471 controls using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by unconditional Logistic regression to analyze the relationship between each genotype and the genetic susceptibility to gastric cancer. The level of C7 expression in GC was analyzed by Gene Expression Profiling Interactive Analysis (GEPIA) and detected by Enzyme Linked Immunosorbent Assay. Kaplan-Meier plotter were used to reveal C7 of prognostic value in GC. We examined SNPs associated with the expression of C7 using the GTEx database. The effect of C7 polymorphisms on the regulatory activity of C7 was detected by luciferase reporter assay. RESULTS: Unconditional logistic regression showed that individuals with C7 rs1376178 AA or CA genotype had a higher risk of GC with OR (95% CI) of 2.09 (1.43-3.03) and 1.88 (1.35-2.63), respectively. For C7 rs1061429 C > A polymorphism, AA genotype was associated with the elevated risk for developing gastric cancer (OR = 2.16, 95% CI [1.37-3.38]). In stratified analysis, C7 rs1376178 AA genotype increased the risk of GC among males (OR = 2.88, 95% CI [1.81-4.58]), but not among females (OR = 1.06, 95% CI [0.55-2.06]). Individuals carrying rs1061429 AA significantly increased the risk of gastric cancer among youngers (OR = 2.84, 95% CI [1.39-5.80]) and non-smokers (OR = 2.79, 95% CI [1.63-4.77]). C7 was overexpressed in gastric cancer tissues and serum of cancer patients and was significantly associated with the prognosis. C7 rs1061429 C > A variant contributed to reduced protein level of C7 (P = 0.029), but rs1376178 didn't. Luciferase reporter assay showed that rs1376178C-containing plasmid exhibited 2.86-fold higher luciferase activity than rs1376178 A-containing plasmid (P < 0.001). We also found that rs1061429A allele contributed 1.34-fold increased luciferase activity than rs1061429C allele when co-transfected with miR-591 (P = 0.0012). CONCLUSIONS: These findings highlight the role of C7 in the development of gastric cancer.

A Distinct Innate Immune Signature of Early Onset Colorectal Cancer.

Despite a decrease in the prevalence of colorectal cancer (CRC) over the last 40 y, the prevalence of CRC in people under 50 y old is increasing around the globe. Early onset (≤50 y old) and late onset (≥65 y old) CRC appear to have differences in their clinicopathological and genetic features, but it is unclear if there are differences in the tumor microenvironment. We hypothesized that the immune microenvironment of early onset CRC is distinct from late onset CRC and promotes tumor progression. We used NanoString immune profiling to analyze mRNA expression of immune genes in formalin-fixed paraffin-embedded surgical specimens from patients with early (n = 40) and late onset (n = 39) CRC. We found three genes, SAA1, C7, and CFD, have increased expression in early onset CRC and distinct immune signatures based on the tumor location. After adjusting for clinicopathological features, increased expression of CFD and SAA1 were associated with worse progression-free survival, and increased expression of C7 was associated with worse overall survival. We also performed gain-of-function experiments with CFD and SAA1 in s.c. tumor models and found that CFD is associated with higher tumor volumes, impacted several immune genes, and impacted three genes in mice that were also found to be differentially expressed in early onset CRC (EGR1, PSMB9, and CXCL9). Our data demonstrate that the immune microenvironment, characterized by a distinct innate immune response signature in early onset CRC, is unique, location dependent, and might contribute to worse outcomes.

Recipient C7 rs9292795 genotype and the risk of hepatocellular carcinoma recurrence after orthotopic liver transplantation in a Han Chinese population.

BACKGROUND: Complement component(C7) gene has been shown to influence the prognosis in Hepatocellular carcinoma (HCC) patients. The association between C7 and HCC recurrence after orthotopic liver transplantation (OLT), however, is still unknown. The purpose of this study was to evaluate whether the donor and recipient C7 gene polymorphisms are related to HCC recurrence after OLT in the Han Chinese population. METHODS: A total of 73 consecutive patients with HCC who had undergone OLT, both donors and recipients, were involved in this research. A single nucleotide polymorphism of C7, rs9292795, was genotyped using Sequenom MassARRAY in the cohort. The expression of C7 and the association between C7 gene polymorphisms and HCC recurrence following OLT were analyzed by bioinformatics and statistical analysis, respectively. RESULTS: As shown in database, the expression of C7 was higher in HCC tissues than that in normal tissues, and represented a worse prognosis. We also found that recipient C7 rs9292795 polymorphism, rather than the donor, was significantly associated with HCC recurrence after OLT. Multivariate logistic regression analysis confirmed that TNM stage (P = 0.001), Milan criteria (P = 0.000) and recipient rs9292795 genotype (TT vs AA/AT, P = 0.008) were independent risk factors for HCC recurrence. Furthermore, the recipient carrying AA/AT showed higher recurrence-free survival (RFS) and overall survival (OS) than that carrying TT (P < 0.05). In Cox proportional hazards model, TNM stage, recipient rs9292795 genotype, and Milan criteria were identified as independent factors for RFS and OS (P < 0.05) as well as pre-OLT serum alpha fetoprotein (AFP) level was associated with OS (P < 0.05). CONCLUSIONS: Recipient C7 rs9292795 gene polymorphism is related to the recurrence of HCC after OLT, which may be a helpful prognostic marker for HCC patients who receive OLT.

Disseminated gonococcal infection in a Japanese man with complement 7 deficiency with compound heterozygous variants: A case report.

RATIONALE: Complement deficiency are known to be predisposed to disseminated gonococcal infection (DGI). We herein present a case of DGI involving a Japanese man who latently had a complement 7 deficiency with compound heterozygous variants. PATIENT CONCERNS: A previously healthy 51-year-old Japanese man complained of sudden-onset high fever. Physical examination revealed various skin lesions including red papules on his trunk and extremities, an impetigo-like pustule on left forearm, and tendinitis of his right forefinger. DIAGNOSIS: Blood culture testing detected gram-negative cocci, which was confirmed to be Neisseria gonorrhoeae based on mass spectrometry and a pathogen-specific PCR test. INTERVENTIONS: Screening tests for underlying immunocompromised factors uncovered that complement activities (CH50) was undetectable. With a suspicion of a congenital complement deficiency, genetic analysis revealed rare single nucleotide variants in complement 7 (C7), including c.281-1G>T and a novel variant c.1454C>T (p.A485V). CH50 was normally recovered by adding purified human C7 to the patient's serum, supporting that the patient has C7 deficiency with compound heterozygous variants. OUTCOMES: Under a diagnosis of DGI, the patient underwent an antibiotic treatment with cefotaxime for a week and was discharged without any sequela. LESSONS: DGI is a rare sexually-transmitted infection that potentially induces systemic complications. Complement immunity usually defeats N. gonorrhoeae and prevents the organism from causing DGI. This case highlighted the importance of suspecting a complement deficiency when a person develops DGI.

Rare Genetic Variants in Immune Genes and Neonatal Herpes Simplex Viral Infections.

Neonatal herpes simplex virus (HSV) infection is a devastating disease with high mortality, particularly when disseminated. Studies in adults and children suggest that susceptibility to herpes simplex encephalitis (HSE) may represent phenotypes for inborn errors in toll-like receptor 3 (TLR3) signaling. However, the genetic basis of susceptibility to neonatal HSV including disseminated disease remains unknown. To test the hypothesis that variants in known HSE-susceptible genes as well as genes mediating HSV immunity will be identified in neonatal HSV, we performed an unbiased exome sequencing study in 10 newborns with disseminated, HSE, and skin, eyes, and mouth disease. Determination of potential impact on function was determined by following American College of Medical Genetics and Genomics guidelines. We identified deleterious and potentially deleterious, rare variants in known HSE-related genes including a stop IRF3 variant (disseminated), nonsynonymous variants in TLR3 and TRAF3 (HSE), STAT1 (skin, eyes, and mouth), and DBR1 (disseminated) in our cohort. Novel and rare variants in other immunodeficiency genes or HSV-related immune genes GRB2, RAG2, PRF1, C6, C7, and MSR1 were found in 4 infants. The variant in GRB2, essential for T-lymphocyte cell responses to HSV, is a novel stop variant not found in public databases. In this pilot study, we identified deleterious or potentially deleterious variants in TLR3 pathway and genes that regulate anti-HSV immunity in neonates with HSV including disseminated disease. Larger, definitive studies incorporating functional analysis of genetic variants are required to validate these data and determine the role of immune genetic variants in neonatal HSV susceptibility.

The complement C7 variant rs3792646 is associated with amyotrophic lateral sclerosis in a Han Chinese population.

The complement system has been shown to have a critical pathogenetic role in amyotrophic lateral sclerosis (ALS). Recently a C7 variant in rs3792646 was linked to neurodegenerative diseases in a Chinese population. We used whole exome sequencing to evaluate the role of C7 (rs3792646) in ALS in a Chinese cohort with 1970 individuals. The minor allele frequency in cases was 0.032 while 0.016 in controls, suggesting this variant was associated with ALS. Further analyses showed the prevalence of the variant was significantly higher in Chinese than Caucasian, suggesting its importance in Han individuals. rs3792646-C was significantly associated with a lower onset age in both genders, and a survival analysis revealed a significant relationship between the variant and decreased survival. There was no significant association between the variant and other common ALS-related variants. Our study further elucidated the relationship between the complement system and ALS from a genetic perspective. In addition, the results suggested C7 (rs3792646) could be a potential predictive factor for poor prognosis in ALS.

The utility of complement assays in clinical immunology: A comprehensive review.

The multi-tasking organ liver, which is the major synthesis site of most serum proteins, supplies humoral components of the innate, - including proteins of the complement system; and, less intensely, also of the acquired immune system. In addition to hepatocyte origins, C1q, factor D, C3, C7 and other protein components of the complement system are produced at various body locations by monocytes/macrophages, lymphocytes, adipocytes, endometrium, enterocytes, keratinocytes and epithelial cells; but the contribution of these alternate sites to the total serum concentrations is slight. The two major exceptions are factor D, which cleaves factor B of the alternative pathway derived largely from adipocytes, and C7, derived largely from polymorphonuclear leukocytes and monocytes/macrophages. Whereas the functional meaning of the extrahepatic synthesis of factor D remains to be elucidated, the local contribution of C7 may up- or downregulate the complement attack. The liver, however, is not classified as part of the immune system but is rather seen as victim of autoimmune diseases, a point that needs apology. Recent histological and cell marker technologies now turn the hands to also conceive the liver as proactive autoimmune disease catalyst. Hosting non-hepatocytic cells, e.g. NK cells, macrophages, dendritic cells as well as T and B lymphocytes, the liver outreaches multiple sites of the immune system. Immunopharmacological follow up of liver transplant recipients teaches us on liver-based presence of ABH-glycan HLA phenotypes and complement mediated ischemia/regeneration processes. In clinical context, the adverse reactions of the complement system can now be curbed by specific drug therapy. This review extends on the involvement of the complement system in liver autoimmune diseases and should allow to direct therapeutic opportunities.

Complement 7 Is Up-Regulated in Human Early Diabetic Kidney Disease.

There is a temporal window from the time diabetes is diagnosed to the appearance of overt kidney disease during which time the disease progresses quietly without detection. Currently, there is no way to detect early diabetic nephropathy (EDN). Herein, we performed an unbiased assessment of gene-expression analysis of postmortem human kidneys to identify candidate genes that may contribute to EDN. We then studied one of the most promising differentially expressed genes in both kidney tissue and blood samples. Differential transcriptome analysis of EDN kidneys and matched nondiabetic controls showed alterations in five canonical pathways, and among them the complement pathway was the most significantly altered. One specific complement pathway gene, complement 7 (C7), was significantly elevated in EDN kidney. Real-time PCR confirmed more than a twofold increase of C7 expression in EDN kidneys compared with controls. Changes in C7 gene product level were confirmed by immunohistochemistry. C7 protein levels were elevated in proximal tubules of EDN kidneys. Serum C7 protein levels were also measured in EDN and control donors. C7 levels were significantly higher in EDN serum than control serum. This latter finding was independently confirmed in a second set of blood samples from a previously collected data set. Together, our data suggest that C7 is associated with EDN, and can be used as a molecular target for detection and/or treatment of EDN.

Two sides of a coin: GG genotype of C7 provides protection against fibrosis severity while showing a higher risk for hepatocellular carcinoma in patients with hepatitis C.

The complement system (CS) is a key element of immunity against pathogens but also seems to influence other events, such as tumorigenesis and tissue repair. Complement component 7 (C7) is a key component of the lytic pathway of CS, leading to the formation of the membrane attack complex (MAC). This study aimed to investigate the existence of the association of a polymorphism in the C7 gene, rs1063499, with hepatic fibrosis and the occurrence of hepatocellular carcinoma (HCC) in patients with hepatitis C. We analyzed 456 samples from patients with chronic hepatitis C. Real-time PCR was used for allelic discrimination. Patients were classified by their METAVIR score as F1 (n = 100), F2 (n = 83), F3 (n = 101) or F4 (n = 66); 106 patients were diagnosed with HCC. Patients carrying the G/G genotype of C7 had a lower chance of developing severe fibrosis in the recessive model (p = 0.042; OR: 0.65 95% CI 0.41-1.02). However, the G/G genotype frequency was higher in patients with HCC (P = 0.01; OR: 2.07 95% CI 1.20-3.53) and in those with larger tumors (p = 0.04). The G/G C7 genotype seems to be a protective factor against advanced fibrosis; however, it was associated with a higher risk of HCC and the occurrence of larger hepatic nodules, suggesting the involvement of C7 in the physiopathogenesis of HCC and fibrosis in patients with hepatitis C virus (HCV).

Membrane attack complex-associated molecules from redlip mullet (Liza haematocheila): Molecular characterization and transcriptional evidence of C6, C7, C8ß, and C9 in innate immunity.

The redlip mullet (Liza haematocheila) is one of the most economically important fish in Korea and other East Asian countries; it is susceptible to infections by pathogens such as Lactococcus garvieae, Argulus spp., Trichodina spp., and Vibrio spp. Learning about the mechanisms of the complement system of the innate immunity of redlip mullet is important for efforts towards eradicating pathogens. Here, we report a comprehensive study of the terminal complement complex (TCC) components that form the membrane attack complex (MAC) through in-silico characterization and comparative spatial and temporal expression profiling. Five conserved domains (TSP1, LDLa, MACPF, CCP, and FIMAC) were detected in the TCC components, but the CCP and FIMAC domains were absent in MuC8ß and MuC9. Expression analysis of four TCC genes from healthy redlip mullets showed the highest expression levels in the liver, whereas limited expression was observed in other tissues; immune-induced expression in the head kidney and spleen revealed significant responses against Lactococcus garvieae and poly I:C injection, suggesting their involvement in MAC formation in response to harmful pathogenic infections. Furthermore, the response to poly I:C may suggest the role of TCC components in the breakdown of the membrane of enveloped viruses. These findings may help to elucidate the mechanisms behind the complement system of the teleosts innate immunity.

Two routes of infection with Photobacterium damselae subsp. piscicida are effective in the modulation of the transcription of immune related genes in Solea senegalensis.

The marine fish pathogen Photobacterium damselae subsp. piscicida (Phdp) is responsible for important disease outbreaks affecting cultured fish species including the flatfish Solea senegalensis. In the present work, transcription of iron metabolism related genes (TF, FERR-M, HP-1 and HAMP-1) as well as innate immune system components such as complement proteins (C3 and C7), lysozyme (LYS-G), TNF family (TNFα, TRAF-3), NCCRP-1 and heat shock protein encoding genes (HSP70, HSP90AA, HSP90AB and GP96) has been determined in the liver and kidney of S. senegalensis specimens after Phdp infection. Intraperitoneal injection (IP) and immersion (IM) routes have been used for infection. Fish developed specific antibodies in both cases, higher levels being detected in IP infected specimens. Both infection routes resulted in increased relative transcript levels of FERR-M, HP-1 and HAMP-1 genes and TF decreased relative transcription, conducting to lower iron availability for the pathogen. This response can be considered as a strategy to limit iron availability for Phdp, a pathogen capable to obtain iron from transferrin. Relative transcription of genes encoding lysozyme and complement factors C3 and C7 were also increased regardless the infection route; the liver was the main organ involved in the initial stages and the kidney in later stages of the infection. TNFα and TRAF-3 relative gene transcription increased 24h post-infection. TRAF-3 gene induction was detected 30 d post-infection, whilst no changes in TNFα were observed 72h or 30 d post-infection. NCCRP-1 changes were observed after IP infection in the liver and kidney; however, IM infection resulted only in slight changes in the kidney of infected fish. This different response observed maybe related to a lower number of invaded cells by the pathogen. Finally, changes in HSP90AB and GP96 have been detected after infection by both routes. Different late modulation has been observed in assayed genes depending on the route of infection. Thus, only LYS-G, TF, NCCRP-1, GP96 and HSP90AB gene transcription was modulated 30 d post-infection in the kidney of IM infected specimens; however, IP infected fish showed modulation in a higher number of genes both in liver and kidney tissues. The implications of these responses in resistance to infection by Phdp need to be elucidated.

C7 genotype of the donor may predict early bacterial infection after liver transplantation.

Post-transplantation infection causes high mortality and remains a significant challenge. High clinical risk factors for bacterial infection in recipients are often found in critically ill patients. However, for some recipients, bacterial infections are inevitable. It is conceivable that this susceptibility may be related to the genetics of the donor and recipient. Using expression quantitative trait loci (eQTL) analysis, we found that the C7 rs6876739 CC genotypes and mannan-binding lectin (MBL2) gene polymorphisms of liver donors were significantly associated with bacterial infection in recipients. In an extended validation group of 113 patients, donor C7 rs6876739 genetic variation was an independent risk factor for bacterial infection. The donor C7 rs6876739 CC genotype was associated with lower levels of recipient C7 protein, soluble membrane attack complex (MAC), and IL-1ß expression compared with the donor C7 rs6876739 TT genotype. In vitro, the MAC significantly triggered NLRP3 inflammasome activation and IL-1ß release, suggesting that the mechanism by which C7 defends against bacteria may involve MAC formation, leading to NLRP3 inflammasome activation and IL-1ß release. Our findings may be helpful in identifying transplantation recipients at risk of bacterial infection prior to surgery and may contribute to novel infection prevention strategies and the improvement of postoperative outcomes.

A 425 T>C polymorphism in complement C7 association with resistance to Aeromonas hydrophila in grass carp.

Aeromonas hydrophila, a widespread bacterium in the aquatic environment, causes hemorrhagic septicemia in fish. In the last decade, the disease has caused mass mortalities and tremendous economic loss in cultured fish. The complement component C7 is a terminal component of complement that interacts in a sequence of polymerization reactions with other terminal complement components to form a membrane attack complex. The formation of the membrane attack complex creates a pore in the membranes of certain pathogen that can lead to their death. The objective of this study was to identify single nucleotide polymorphisms (SNPs) in the C7 gene and to assess their association with A. hydrophila resistance in grass carp. A resource population consisting of 186 susceptible and 191 resistant grass carp was constructed. We sequenced a total of 7826 bp of the C7 gene and identified 6 SNPs that were genotyped in the resource population. The SNP -1575 A>C was positioned in the promoter region of the gene. The SNP 425 C>T identified in the coding exon was a synonymous substitution in the fourth exon. Statistical analysis showed that SNP 425 C>T was associated with the incidence of hemorrhagic septicemia. The SNPs -1575 A>C, -688 T>C, and -266 A>C were highly linked together (r(2) > 0.85). No haplotypes generated with these 3 SNPs were associated with resistance to A. hydrophila in grass carp. These findings suggest that the 425 C>T polymorphism in C7 gene may be a significant molecular marker for resistance to A. hydrophila in grass carp.

Characterisation and expression analysis of two terminal complement components: C7 and C9 from large yellow croaker, Larimichthys crocea.

The large yellow croaker Larimichthys crocea, as one of the most economically important marine fish in China and East Asian countries, are facing the fatal attraction of various pathogens in recent years. Elucidation of the organism immunomodulatory mechanism of croaker response to pathogen infection is essential for the disease control. In present study, we reported for the first time the molecular characterization and expression analysis of two terminal complement components (TCCs) of croaker, Lc-C7 and Lc-C9. These two structural conserved TCCs were detected in many tissues in adult healthy fish, with highest levels detected in liver. The transcriptional expression analysis of Lc-C7 and Lc-C9 at different developmental stages showed a continuous increase towards hatch, however the two TCCs mRNA were not detected at the unfertilized stage, hinting the origination of these two TCCs after fertilization. Rapid and drastic responses to Vibrio alginolyticus challenge were observed for Lc-C7 and Lc-C9, suggesting the involvement of component C7 and C9 in innate immune responses to pathogenic invasion in teleost fish. These findings could deepen our understanding about immunomodulatory mechanisms of croaker and shed a new light to the role of component system in teleostean immunomodulation.

Complement proteins C7 and CFH control the stemness of liver cancer cells via LSF-1.

Tumor-initiating cells are important for the formation and maintenance of tumor bulks in various tumors. To identify surface markers of liver tumor-initiating cells, we performed primary tumorsphere culture and analyzed the expression of cluster of differentiation (CD) antigen genes using NanoString. Interestingly, we found significant upregulation of the complement proteins (p = 1.60 × 10(-18)), including C7 and CFH. Further studies revealed that C7 and CFH are required to maintain stemness in liver cancer cells. Knockdown of C7 and CFH expression abrogated tumorsphere formation and induced differentiation, whereas overexpression stimulated stemness factor expression as well as in vivo cell growth. Mechanistically, by studying C7 and CFH-dependent LSF-1 expression and its direct role on stemness factor transcription, we found that LSF-1 is involved in this regulation. Taken together, our data demonstrate the unprecedented role of complement proteins on the maintenance of stemness in liver tumor-initiating cells.

[Recurrent meningitis and inherited complement deficiency]. / Recidivující meningitidy a vrozený deficit komplementového systému.

Complement deficiency represents 5% of primary immunodeficiencies worldwide. A total of seven patients with deficiencies of the classical complement pathway were reported in the Czech Republic by the end of 2015. Typical manifestations of complement deficiency are recurrent meningitis, other bacterial infections, autoimmunity and kidney disease.Two case reports are presented of patients with molecularly confirmed C7 (compound heterozygote, c.663_644del in exon 6 and c.2350+2T:>C in intron 16) and C8 (homozygous c.1282C>T in exon 9) deficiency. The first patient had four attacks of meningococcal meningitis and an episode of pneumonia of unknown aetiology in childhood. The second had six attacks of meningitis. He also suffered from recurrent infections (otitis media, tonsillitis, chronic mucopurulent rhinitis and subsequent pansinusitis complicated by nasal polyposis) since childhood. No autoimmune disease was documented in either patient. They both received meningococcal and pneumococcal vaccines. Antibiotic prophylaxis was used only in the second patient, leading to a decline in the number of ENT infections.Complement deficiency should be suspected in patients with recurrent meningococcal infections, especially if combined with other infections caused by encapsulated bacteria or autoimmunity diseases. Prophylaxis with conjugate polysaccharide vaccines is recommended and antibiotic prophylaxis should be considered in individual cases.