Ficolin-2 levels and FCN2 haplotypes influence hepatitis B infection outcome in Vietnamese patients

Loss of ficolin-3 expression is associated with poor prognosis in patients with hepatocellular carcinoma

Background: Ficolin-3 (FCN3) is a well-known circulating pattern recognition molecule which plays a role in host immune responses to cancer via activation of the lectin complement pathway. Nevertheless, the clinical significance of FCN3 in patients with hepatocellular carcinoma (HCC) is unclear. Methods: Eighty-seven HCC patients who received hepatectomy at our hospital were included. Immunohistochemical staining was used to assess the FCN3 expression in both tumorous and non-tumorous tissues from the patients, who were classified into high and low expression groups. Differences in clinicopathological characteristics between the two groups were then analyzed. Results: Survival was significantly associated with FCN3 immunohistochemical score (p for trend = 0.048). Kaplan-Meier analysis revealed a higher overall survival rate in the patients with a high FCN3 expression than in those with a low FCN3 expression (p=0.031). A high FCN3 expression in tumor tissue was independently associated with better overall survival (p=0.042). However, multivariate analysis showed that FCN3 expression was not an independent risk factor for overall survival. Conclusion: Our findings suggest that FCN3 is significantly related to the prognosis of HCC. FCN3 may be a prognostic marker in patients with HCC.

Immune response and treatment targets of chronic hepatitis B virus infection: innate and adaptive immunity

Chronic hepatitis B virus (HBV) infection is a major global public health risk that threatens human life and health, although the number of vaccinated people has increased. The clinical outcome of HBV infection depends on the complex interplay between viral replication and the host immune response. Innate immunity plays an important role in the early stages of the disease but retains no long-term immune memory. However, HBV evades detection by the host innate immune system through stealth. Therefore, adaptive immunity involving T and B cells is crucial for controlling and clearing HBV infections that lead to liver inflammation and damage. The persistence of HBV leads to immune tolerance owing to immune cell dysfunction, T cell exhaustion, and an increase in suppressor cells and cytokines. Although significant progress has been made in HBV treatment in recent years, the balance between immune tolerance, immune activation, inflammation, and fibrosis in chronic hepatitis B remains unknown, making a functional cure difficult to achieve. Therefore, this review focuses on the important cells involved in the innate and adaptive immunity of chronic hepatitis B that target the host immune system and identifies treatment strategies.

Selected SNPs of FCN2 Associated with Chronic Tonsillitis in the Polish Adult Population

Chronic tonsillitis is a problem related to bacterial and viral infections. Ficolins play a key role in the defence against various pathogens. In the present study, we investigated the associations between the selected single nucleotide polymorphisms (SNPs) of the FCN2 gene and chronic tonsillitis in the Polish population. The study included 101 patients with chronic tonsillitis and 101 healthy individuals. The selected SNPs of FCN2 (rs3124953, rs17514136 and rs3124954) were genotyped using TaqMan SNP Genotyping Assays (Applied Biosystem, Foster City, CA, USA). The analysis of rs17514136 and rs3124953 showed no significant differences in genotype frequencies between the chronic tonsillitis patients and controls (p > 0.01). The CT genotype of rs3124954 was significantly more frequent, while the CC genotype was less frequent in chronic tonsillitis patients (p = 0.003 and p = 0.001, respectively). The frequency of the A/G/T haplotype (rs17514136/rs3124953/rs3124954) was significantly more common in chronic tonsillitis patients (p = 0.0011). Moreover, the FCN2 CT genotype of rs3124954 was associated with a higher risk of chronic tonsillitis, while the CC genotype of rs3124954 decreased this risk. Our findings demonstrate that FCN2 rs3124954 may be associated with chronic tonsillitis in the Polish adult population.

Methodological Appraisal of Literature Concerning the Analysis of Genetic Variants or Protein Levels of Complement Components on Susceptibility to Infection by Trypanosomatids: A Systematic Review

Background

Trypanosomatids are protozoa responsible for a wide range of diseases, with emphasis on Chagas Disease (CD) and Leishmaniasis, which are in the list of most relevant Neglected Tropical Diseases (NTD) according to World Health Organization (WHO). During the infectious process, immune system is immediately activated, and parasites can invade nucleated cells through a broad diversity of receptors. The complement system − through classical, alternative and lectin pathways − plays a role in the first line of defense against these pathogens, acting in opsonization, phagocytosis and lysis of parasites. Genetic modifications in complement genes, such as Single Nucleotide Polymorphisms (SNPs), can influence host susceptibility to these parasites and modulate protein expression.

Methods

In March and April 2021, a literature search was conducted at the PubMed and Google Scholar databases and the reference lists obtained were verified. After applying the inclusion and exclusion criteria, the selected studies were evaluated and scored according to eleven established criteria regarding their thematic approach and design, aiming at the good quality of publications.

Results

Twelve papers were included in this systematic review: seven investigating CD and five focusing on Leishmaniasis. Most articles presented gene and protein approaches, careful determination of experimental groups, and adequate choice of experimental techniques, although several of them were not up-to-date. Ten studies explored the association of polymorphisms and haplotypes with disease progression, with emphasis on lectin complement pathway genes. Decreased and increased patient serum protein levels were associated with susceptibility to CD and Visceral Leishmaniasis, respectively.

Conclusion

This systematic review shows the influence of genetic alterations in complement genes on the progression of several infectious diseases, with a focus on conditions caused by trypanosomatids, and contributes suggestions and evidence to improve experimental design in future research proposals.

Pattern Recognition Molecules of Lectin Complement Pathway in Ischemic Stroke

Purpose

The current study aimed to investigate in an Armenian population the levels of pattern recognition molecules (PRMs) of lectin complement pathway (LCP), MBL (mannan-binding lectin) and M-ficolin in plasma in ischemic stroke (IS), and the possible association of 11 single nucleotide polymorphisms (SNPs) in MBL2, FCN1 and FCN2 genes.

Patients and Methods

A total of 122 patients with IS and 150 control subjects were included in this study. Immunofluorometric assays (TRIFMAs) and real-time polymerase chain reactions with TaqMan probes were conducted.

Results

According to the results, the levels of M-ficolin in IS patients are significantly higher than in control subjects, and the MBL2 rs11003125 and rs12780112 SNPs, as well as MBL2 rs12780112*T and FCN1 rs10120023*T minor alleles (MAs) are negatively associated with the risk of IS. Further, MBL2 rs11003125 and rs1800450 SNPs and the carriage of their MAs, as well as FCN1 rs2989727 SNP and the carriage of FCN1 rs10120023*T MA significantly alter plasma MBL and M-ficolin levels in IS patients, respectively. Five common haplotypes in MBL2 gene and three common haplotypes in FCN1 and FCN2 genes were revealed, among which CGTC was negatively associated with IS and decreasing MBL plasma levels in IS.

Conclusion

In conclusion, we suggest that LCP PRMs are associated with the risk of developing IS, and may also participate in pathological events leading to post-ischemic brain damage. This study emphasizes the important contribution of alterations of LCP PRMs on genomic and proteomic levels to the pathomechanisms of ischemic stroke, at least in an Armenian population.

Analysis of genomic DNA from medieval plague victims suggests long-term effect of Yersinia pestis on human immunity genes

Pathogens and associated outbreaks of infectious disease exert selective pressure on human populations, and any changes in allele frequencies that result may be especially evident for genes involved in immunity. In this regard, the 1346-1353 Yersinia pestis-caused Black Death pandemic, with continued plague outbreaks spanning several hundred years, is one of the most devastating recorded in human history. To investigate the potential impact of Y. pestis on human immunity genes we extracted DNA from 36 plague victims buried in a mass grave in Ellwangen, Germany in the 16th century. We targeted 488 immune-related genes, including HLA, using a novel in-solution hybridization capture approach. In comparison with 50 modern native inhabitants of Ellwangen, we find differences in allele frequencies for variants of the innate immunity proteins Ficolin-2 and NLRP14 at sites involved in determining specificity. We also observed that HLA-DRB1*13 is more than twice as frequent in the modern population, whereas HLA-B alleles encoding an isoleucine at position 80 (I-80+), HLA C*06:02 and HLA-DPB1 alleles encoding histidine at position 9 are half as frequent in the modern population. Simulations show that natural selection has likely driven these allele frequency changes. Thus, our data suggests that allele frequencies of HLA genes involved in innate and adaptive immunity responsible for extracellular and intracellular responses to pathogenic bacteria, such as Y. pestis, could have been affected by the historical epidemics that occurred in Europe.

Association of ficolin-2 gene polymorphisms and susceptibility to systemic lupus erythematosus in Egyptian children and adolescents: a multicenter study

BACKGROUND

Pediatric-onset SLE (pSLE) is a multisystem autoimmune disease. Recently, the ficolin-2 (FCN2) gene has emerged as a potential candidate gene for susceptibility to SLE.

OBJECTIVES

The objective of this study was to evaluate the association of the FCN2 gene polymorphisms at positions -986 (G/A), -602 (G/A), -4 (A/G) and SNP C/T (rs3124954) located in intron 1, with susceptibility to pSLE in Egyptian children and adolescents.

METHODS

This was a multicenter study of 280 patients diagnosed with pSLE, and 280 well-matched healthy controls. The FCN2 promoter polymorphisms at -986 G/A (rs3124952), -602 G/A (rs3124953), -4 A/G (rs17514136) and SNP C/T (rs3124954) located in intron 1 were genotyped by polymerase chain reaction, while serum ficolin-2 levels were assessed using enzyme-linked immunosorbent assay.

RESULTS

The frequencies of the FCN2 GG genotype and G allele at -986 and -602 positions were significantly more represented in patients with pSLE than in controls (p < 0.001). Conversely, the FCN2 AA genotype and A allele at position -4 were more common in patients than in controls (p < 0.001). Moreover, patients carrying the FCN2 GG genotype in -986 position were more likely to develop lupus nephritis (odds ratio: 2.6 (95% confidence interval: 1.4-4.78); p = 0.006). The FCN2 AA genotype at position -4 was also identified as a possible risk factor for lupus nephritis (odds ratio: 3.12 (95% confidence interval: 1.25-7.84); p = 0.024).

CONCLUSION

The FCN2 promoter polymorphisms may contribute to susceptibility to pSLE in Egyptian children and adolescents. Moreover, the FCN2 GG genotype at position -986 and AA genotype at position -4 were associated with low serum ficolin-2 levels and may constitute risk factors for lupus nephritis in pSLE.

Elevated serum activity of MBL and ficolin-2 as biomarkers for progression to hepatocellular carcinoma in chronic HCV infection

Hepatocellular carcinoma (HCC) is an uncommon but significant outcome of chronic hepatitis C virus (HCV) infection. A serum biomarker for predicting progression to HCC would have a major impact on patient monitoring and clinical management. We explored circulating liver-expressed lectins, ficolin-2, ficolin-3 and mannose binding lectin (MBL), as potential biomarkers for the development of HCC. The activity of these three lectins were analysed in HCV positive patients who developed HCC (n = 31) with comparable HCV-positive HCC-negative patients (n = 106) and healthy controls (n = 79). Serum binding activity of ficolin-2 and MBL were elevated compared to controls. Analysis of pre-HCC onset samples revealed that MBL levels were significantly elevated up to 3 years, and ficolin-2 was elevated up to 1 year, prior to diagnosis of HCC over controls. This preliminary study identifies MBL and ficolin-2 as potential biomarkers for the development of HCC in chronic HCV infection.

A Rare Genetic Defect of MBL2 Increased the Risk for Progression of IgA Nephropathy

The aim of this study was to investigate the association between lectin pathway-related genetic variations and progression in IgA nephropathy. Biopsy-proven IgAN patients with eGFR ≥15 ml/min/1.73 m2 at baseline and a minimum follow-up of 12-months were enrolled. A total of 1,007 patients and 121 healthy controls were enrolled from two Chinese renal centers. The discovery cohort consisted of 606 patients, and the validation cohort consisted of 401 patients. First, promoters, all exons and their boundary regions of MBL2 and FCN2 were sequenced in 50 patients, and then 37 variations were identified. Of these variations, 7 expression-associated variations were selected and genotyped in the whole discovery cohort. We found that rs1800450 in MBL2 and rs7851696 in FCN2 were associated with an increased risk for ESRD as well as serum MBL or L-ficolin levels. However, only rs1800450 was successively validated for its association with ESRD (HR, 15.91; 3.27-77.34; P = 0.001) in the fully adjusted model in the validation cohort. In addition, 2.7% of patients, and 2.5% of healthy controls carried rs1800450-AA. IgAN patients with rs1800450-AA lacked expression of MBL in both serum and renal tissue and had more severe tubulointerstitial damage. Furthermore, a combined effect of rs1800450-AA with a previously reported clinical risk score was observed in which patients with both a high clinical risk score (≥1%) and rs1800450-AA had a strikingly increased 10-years ESRD risk by 37.1-fold (7.17 to 192.13-fold). In summary, IgAN patients carrying MBL2 rs1800450-AA have a high risk for renal function deterioration, probably due to inactivation of the complement MBL pathway.

Serum Proteomic Changes as Candidate Biomarkers of Intermediate Liver Fibrosis in Chronic Hepatitis B Infection

Chronic hepatitis B (CHB) is a major global health burden. Liver fibrosis, an insidious process, is the main histopathological change in CHB that might lead to the end-stage liver disease if left untreated. The intermediate liver fibrosis (S2) is the optimal time to start antiviral therapy. The aim of the present study was to examine the proteomic changes in patients with CHB at different fibrotic stages, with a view to identify future serum biomarkers for S2. Ninety CHB patients were grouped into mild (S0-1), intermediate (S2), and severe liver fibrosis (S3-4) (61 men and 29 women; age 25-63 years). Isobaric tagging for relative and absolute quantitation was applied to screen proteins differentially expressed among the patient groups. Another 46 patients with CHB (age 25-59 years; 31 men and 15 women), and 16 healthy controls (age 26-61 years; 11 men and 5 women) were enrolled in a validation group. Enzyme-linked immunosorbent assay was used to verify the diagnostic value of the candidate biomarkers. We found 139 proteins that were differentially expressed between various fibrotic stage-paired comparisons. Five protein candidates were selected as potential biomarkers of S2 for further verification. Notably, ficolin-2 (FCN2) and carboxypeptidase B2 (CPB2) showed differential expression between patients and healthy controls. In conclusion, serum proteomic changes reported here offer new molecular leads for future research on biomarker candidates to identify liver fibrotic stages in CHB. In particular, FCN2 and CPB2 warrant further research on their possible mechanistic involvement in CHB pathogenesis.

Ficolins and the Recognition of Pathogenic Microorganisms: An Overview of the Innate Immune Response and Contribution of Single Nucleotide Polymorphisms

Ficolins are innate pattern recognition receptors (PRR) and play integral roles within the innate immune response to numerous pathogens throughout the circulation, as well as within organs. Pathogens are primarily removed by direct opsonisation following the recognition of cell surface carbohydrates and other immunostimulatory molecules or via the activation of the lectin complement pathway, which results in the deposition of C3b and the recruitment of phagocytes. In recent years, there have been a number of studies implicating ficolins in the recognition and removal of numerous bacterial, viral, fungal, and parasitic pathogens. Moreover, there has been expanding evidence highlighting that mutations within these key immune proteins, or the possession of particular haplotypes, enhance susceptibility to colonization by pathogens and dysfunctional immune responses. This review will therefore encompass previous knowledge on the role of ficolins in the recognition of bacterial and viral pathogens, while acknowledging the recent advances in the immune response to fungal and parasitic infections. Additionally, we will explore the various genetic susceptibility factors that predispose individuals to infection.

Ficolin-1 and Ficolin-3 Plasma Levels Are Altered in HIV and HIV/HCV Coinfected Patients From Southern Brazil

The complement system is a key component of the innate immune system, participating in the surveillance against infectious agents. Once activated by one of the three different pathways, complement mediates cell lysis, opsonization, signalizes pathogens for phagocytosis and induces the adaptive immune response. The lectin pathway is constituted by several soluble and membrane bound proteins, called pattern recognition molecules (PRM), including mannose binding lectin (MBL), Ficolins-1, -2, and -3, and Collectin 11. These PRMs act on complement activation as recognition molecules of pathogen-associated molecular patterns (PAMPs) such as N-acetylated, found in glycoproteins of viral envelopes. In this study, Ficolin-1 and Ficolin-3 plasma levels were evaluated in 178 HIV patients (93 HIV; 85 HIV/HCV) and 85 controls from southern Brazil. Demographic and clinical-laboratory findings were obtained during medical interview and from medical records. All parameters were assessed by logistic regression, adjusted for age, ancestry, and sex. Significantly lower levels of Ficolin-1 were observed in HIV/HCV coinfected when compared to HIV patients (p = 0.005, median = 516 vs. 667 ng/ul, respectively) and to controls (p < 0.0001, 1186 ng/ul). Ficolin-1 levels were lower in males than in females among HIV patients (p = 0.03) and controls (p = 0.0003), but no association of Ficolin-1 levels with AIDS was observed. On the other hand, Ficolin-3 levels were significantly lower in controls when compared to HIV (p < 0.0001, medians 18,240 vs. 44,030 ng/ml, respectively) and HIV/HCV coinfected (p < 0.0001, 40,351 ng/ml) patients. There was no correlation between Ficolin-1 and Ficolin-3 levels and age, HIV viral load or opportunistic infections. However, Ficolin-3 showed a positive correlation with T CD4 cell counts in HIV monoinfected patients (p = 0.007). We provide here the first assessment of Ficolin-1 and-3 levels in HIV and HIV/HCV coinfected patients, which indicates a distinct role for these pattern recognition molecules in both viral infections.

Common and rare genetic variants of complement components in human disease

Genetic variability in the complement system and its association with disease has been known for more than 50 years, but only during the last decade have we begun to understand how this complement genetic variability contributes to the development of diseases. A number of reports have described important genotype-phenotype correlations that associate particular diseases with genetic variants altering specific aspects of the activation and regulation of the complement system. The detailed functional characterization of some of these genetic variants provided key insights into the pathogenic mechanisms underlying these pathologies, which is facilitating the design of specific anti-complement therapies. Importantly, these analyses have sometimes revealed unknown features of the complement proteins. As a whole, these advances have delineated the functional implications of genetic variability in the complement system, which supports the implementation of a precision medicine approach based on the complement genetic makeup of the patients. Here we provide an overview of rare complement variants and common polymorphisms associated with disease and discuss what we have learned from them.

Lectin-complement pathway molecules are decreased in patients with cirrhosis and constitute the risk of bacterial infections

BACKGROUND & AIMS

Lectin pathway molecules of the complement system are synthesized by hepatocytes and have pivotal role in innate host defence against infectious organisms. Ficolins (FCNs) act as soluble pattern recognition molecules, while mannan-binding lectin serine proteases(MASPs) do as effector molecules in elimination of pathogens. We aimed to study the significance of low level of these molecules in the development of cirrhosis-associated bacterial infections, which has not been elucidated so far.

METHODS

Sera of 266 stable outpatients with cirrhosis and 160 healthy subjects were assayed for a panel of lectin molecules (FCN-2, FCN-3 and MASP-2) by ELISA. In cirrhosis, a 5-year follow-up observational study was conducted to assess a possible association between lectin levels and development of clinically significant bacterial infections(CSI).

RESULTS

FCN-2, FCN-3 and MASP-2 levels were significantly lower in cirrhosis compared to healthy subjects and decreased according to disease severity (P<.001 for all molecules). In Kaplan-Meier analysis, development of CSI was associated with low level of FCN-2 (<427 ng/mL, pLogRank=0.047) and FCN-3 (<4857 ng/mL, pLogRank=0.029), but not with MASP-2 deficiency (<100 ng/mL, pLogRank=0.306). Combined FCN deficiency was associated with increased risk of development of bacterial infections in a step-wise manner. Patients with low level of both FCNs had higher cumulative probability of CSI (63.8%) compared to those with low level of one or normal FCN (52.7% and 45.7%, pLogRank=0.016). Neither FCN serum profile, nor MASP-2 deficiency were associated with infection-related mortality.

CONCLUSIONS

Low level of FCNs associated with hepatic insufficiency might be considered as an additional constituent of cirrhosis-associated immune dysfunction.

The Lack of Association between FCN2 Gene Promoter Region Polymorphisms and Dental Caries in Polish Children

The aim of this study was to examine the association of single-nucleotide polymorphisms (SNPs) in the gene encoding ficolin-2 protein (FCN2 gene) at positions -986 (rs17514136), -602 (rs3124953), and -4 (rs3124952) with dental caries in Polish children. Two hundred and sixty Polish Caucasian children aged 15 years were enrolled in this study: 82 with "higher" caries experience (DMFT >5) and 178 with "lower" caries experience (DMFT ≤5). In addition, subjects with caries experience (DMFT ≥1) and caries-free subjects (DMFT = 0) were compared. FCN2 SNPs were genotyped with PCR-RFLP methods. There were no significant differences in the genotype, allele, or haplotype distributions in 3 analyzed SNPs of the FCN2 gene between children with "higher" and those with "lower" caries experience as well as between children with caries experience and caries-free children. In conclusion, we did not find any association of FCN2 promoter polymorphisms at positions -986, -602, and -4 with dental caries in Polish children.

Microarray-based identification of genes associated with cancer progression and prognosis in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths. The average survival and 5-year survival rates of HCC patients still remains poor. Thus, there is an urgent need to better understand the mechanisms of cancer progression in HCC and to identify useful biomarkers to predict prognosis.

METHODS

Public data portals including Oncomine, The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) profiles were used to retrieve the HCC-related microarrays and to identify potential genes contributed to cancer progression. Bioinformatics analyses including pathway enrichment, protein/gene interaction and text mining were used to explain the potential roles of the identified genes in HCC. Quantitative real-time polymerase chain reaction analysis and Western blotting were used to measure the expression of the targets. The data were analysed by SPSS 20.0 software.

RESULTS

We identified 80 genes that were significantly dysregulated in HCC according to four independent microarrays covering 386 cases of HCC and 327 normal liver tissues. Twenty genes were consistently and stably dysregulated in the four microarrays by at least 2-fold and detection of gene expression by RT-qPCR and western blotting showed consistent expression profiles in 11 HCC tissues compared with corresponding paracancerous tissues. Eleven of these 20 genes were associated with disease-free survival (DFS) or overall survival (OS) in a cohort of 157 HCC patients, and eight genes were associated with tumour pathologic PT, tumour stage or vital status. Potential roles of those 20 genes in regulation of HCC progression were predicted, primarily in association with metastasis. INTS8 was specifically correlated with most clinical characteristics including DFS, OS, stage, metastasis, invasiveness, diagnosis, and age.

CONCLUSION

The significantly dysregulated genes identified in this study were associated with cancer progression and prognosis in HCC, and might be potential therapeutic targets for HCC treatment or potential biomarkers for diagnosis and prognosis.

FCN2 inhibits epithelial-mesenchymal transition-induced metastasis of hepatocellular carcinoma via TGF-β/Smad signaling

Hepatocellular carcinoma (HCC) is currently still a major cause of cancer-related deaths. Identifying early metastatic biomarkers and therapeutic targets for HCC is of great importance. Emerging evidence suggest that epithelial-mesenchymal transitions (EMTs) play important roles in tumor metastasis and recurrence. Understanding molecular mechanisms that regulate the EMT process is crucial for improving HCC. In this study, we find Ficolin-2 (FCN2) plays an essential role in metastasis and EMT of HCC. FCN2 expression is downregulated in HCC cells and tissues. Low level of FCN2 in HCCs is correlated with aggressive metastatic features, and would be a prognostic factor for overall disease-free survival of HCC patients. Ectopic expression of FCN2 markedly inhibits HCC cells migration, invasion as well as EMT in vitro and in vivo. Moreover, TGF-β is found contribute to the function of FCN2 in suppressing metastasis and EMT of HCC. Collectively, our data suggest that FCN2 may have prognostic value in HCC metastasis. Additionally, the FCN2/ TGF-β/EMT axis identified in this study provides novel insight into the mechanisms of HCC metastasis, which may facilitate the development of new therapeutics against HCC.

Association of the FCN2 Gene Single Nucleotide Polymorphisms with Susceptibility to Pulmonary Tuberculosis

Ficolin-2 (FCN2) is an innate immune pattern recognition molecule that can activate the complement pathway, opsonophagocytosis, and elimination of the pathogens. The present study aimed to investigate the association of the FCN2 gene single nucleotide polymorphisms (SNPs) with susceptibility to pulmonary tuberculosis (TB). A total of seven SNPs in exon 8 (+6359 C>T and +6424 G>T) and in the promoter region (-986 G>A, -602 G>A, -557 A>G, -64 A>C and -4 A>G) of the FCN2 gene were genotyped using the PCR amplification and DNA sequencing methods in the healthy controls group (n = 254) and the pulmonary TB group (n = 282). The correlation between SNPs and pulmonary TB was analyzed using the logistic regression method. The results showed that there were no significant differences in the distribution of allelic frequencies of seven SNPs between the pulmonary TB group and the healthy controls group. However, the frequency of the variant homozygous genotype (P = 0.037, -557 A>G; P = 0.038, -64 A>C; P = 0.024, +6424 G>T) in the TB group was significantly lower than the control group. After adjustment for age and gender, these variant homozygous genotypes were found to be recessive models in association with pulmonary TB. In addition, -64 A>C (P = 0.047) and +6424 G>T (P = 0.03) were found to be codominant models in association with pulmonary TB. There was strong linkage disequilibrium (r2 > 0.80, P < 0.0001) between 7 SNPs except the -602 G>A site. Therefore, -557 A>G, -64 A>C and +6424 G>T SNPs of the FCN2 gene were correlated with pulmonary TB, and may be protective factors for TB. This study provides a novel idea for the prevention and control of TB transmission from a genetics perspective.

Serum ficolin-2 concentrations are significantly changed in patients with hepatitis B virus infection and liver diseases

Human ficolin-2 is an important lectin complement pathway activator that is secreted from liver cells and has been implicated as an anti-infection innate immune molecule. However, the role of ficolin-2 protein and its dynamic changes over the course of and in the prognosis of chronic hepatitis B (CHB) and hepatocellular carcinoma (HCC) remain unclear. In this study, we analyzed ficolin-2 protein expression in a cohort of individuals with CHB infection, HCC and cirrhosis. A sandwich enzyme-linked immunosorbent assay (ELISA) method was used to measure serum ficolin-2 concentrations. Ficolin-2 expression in liver tissues was detected by immunohistochemical staining. Serum ficolin-2 concentrations in CHB patients were significantly higher than in healthy controls and HBV carriers. After 48 weeks of routine amelioration liver function treatment, serum ficolin-2 concentrations decreased and were positively correlated with favorable alanine aminotransferase (ALT), HBV DNA and HBeAg-seroconversion outcomes. Interestingly, we observed much lower expression of serum and intrahepatic ficolin-2 in HCC and cirrhosis compared with healthy controls. Our findings suggest that serum and intrahepatic ficolin-2 levels may be considered one of the indicators for the response of chronic HBV infection, HCC and cirrhosis.

Low MBL-associated serine protease 2 (MASP-2) levels correlate with urogenital schistosomiasis in Nigerian children

OBJECTIVES

The human mannose-binding lectin (MBL) and ficolins (FCN) are involved in pathogen recognition in the first line of defence. They support activation of the complement lectin cascade in the presence of MBL-associated serine protease 2 (MASP-2), a protein that cleaves the C4 and C2 complement components. Recent studies found that distinct MBL2 and FCN2 promoter variants and their corresponding serum levels are associated with relative protection from urogenital schistosomiasis.

METHODS

We investigated the contribution of MASP-2 levels and MASP2 polymorphisms in a Nigerian study group, of 163 individuals infected with Schistosoma haematobium and 183 healthy subjects.

RESULTS

MASP-2 serum levels varied between younger children (≤12 years) and older children (>12 years) and adults (P = 0.0001). Younger children with a patent infection had significantly lower MASP-2 serum levels than uninfected children (P = 0.0074). Older children and adults (>12 years) with a current infection had higher serum MASP-2 levels than controls (P = 0.032). MBL serum levels correlated positively with MASP-2 serum levels (P = 0.01). MASP2 secretor haplotypes were associated with MASP-2 serum levels in healthy subjects. The heterozygous MASP2 p.P126L variant was associated with reduced serum MASP-2 levels (P = 0.01).

CONCLUSIONS

The findings indicate that higher MASP-2 serum levels are associated with relative protection from urogenital schistosomiasis in Nigerian children.

Association of Ficolin-2 Serum Levels and FCN2 Genetic Variants with Indian Visceral Leishmaniasis

BACKGROUND

Visceral leishmaniasis (VL), one of the neglected tropical diseases, is endemic in the Indian subcontinent. Ficolins are circulating serum proteins of the lectin complement system and involved in innate immunity.

METHODS

We have estimated ficolin-2 serum levels and analyzed the functional variants of the encoding gene FCN2 in 218 cases of VL and in 225 controls from an endemic region of India.

RESULTS

Elevated levels of serum ficolin-2 were observed in VL cases compared to the controls (adjusted P<0.0001). The genetic analysis revealed that the FCN2 structural variant +6359 C>T (p.T236M) was associated with VL (OR=2.2, 95% CI=1.23-7.25, P=0.008) and with high ficolin-2 serum levels. We also found that the FCN2*AAAC haplotype occurred more frequently among healthy controls when compared to cases (OR=0.59, 95%CI=0.37-0.94, P=0.023).

CONCLUSIONS

Our findings indicate that the FCN2 variant +6359C>T is associated with the occurrence of VL and that ficolin-2 serum levels are elevated in Leishmania infections.

Lectin complement protein Collectin 11 (CL-K1) and susceptibility to urinary schistosomiasis

BACKGROUND

Urinary Schistosomiasis is a neglected tropical disease endemic in many sub Saharan -African countries. Collectin Kidney 1 (CL-K1, encoded by COLEC11 on chromosome 2p25.3), a member of the vertebrate C-type lectin super family, has recently been identified as pattern-recognition molecule (PRR) of the lectin complement pathway. CL-K1 is preferentially expressed in the kidneys, but also in other organs and it is considered to play a role in host defense to some infectious agents. Schistosome teguments are fucosylated and CL-K1 has, through its collagen-like domain, a high binding affinity to fucose.

METHODOLOGY/PRINCIPAL FINDINGS

We utilized a Nigerian study group consisting of 167 Schistosoma haematobium infected individuals and 186 matched healthy subjects, and investigated the contribution of CL-K1 deficiency and of COLEC11 polymorphisms to infection phenotype. Higher CL-K1 serum levels were associated with decreased risk of schistosome infection (P corr = 0.0004). CL-K1 serum levels were differentially distributed between the COLEC11 genotypes and haplotypes observed. The non-synonymous variant p.R216H was associated with the occurrence of schistosomiasis (OR = 0.44, 95%CI = 0.22-0.72, P corr = 0.0004). The reconstructed COLEC11*TCCA haplotypes were associated with higher CL-K1 serum levels (P = 0.002) and with decreased schistosomiasis (OR = 0.38, 95%CI = 0.23-0.63, P corr = 0.0001).

CONCLUSIONS

In agreement with findings from our earlier published study, our findings support the observation that CL-K1 and their functional variants may be host factors associated with protection in schistosomiasis and may be a useful marker for further investigations.

New insights into the role of ficolins in the lectin pathway of innate immunity

In the innate immune system, a variety of recognition molecules provide the first-line host defense to prevent infection and maintain endogenous homeostasis. Ficolin is a soluble recognition molecule, which senses pathogen-associated molecular patterns on microbes and aberrant sugar structures on self-cells. It consists of a collagen-like stalk and a globular fibrinogen-like domain, the latter binding to carbohydrates such as N-acetylglucosamine. Ficolins have been widely identified in animals from higher invertebrates to mammals. In mammals, ficolins form complexes with mannose-binding lectin-associated serine proteases (MASPs), and ficolin-MASP complexes trigger complement activation via the lectin pathway. Once activated, complement mediates many immune responses including opsonization, phagocytosis, and cytokine production. Although the precise function of each ficolin is still under investigation, accumulating information suggests that ficolins have a crucial role in host defense by recognizing a variety of microorganisms and interacting with effector proteins.

MBL2 polymorphisms in women with atypical squamous cells of undetermined significance

Infection with high risk Human papillomavirus (HPV) is the main known cause of cervical cancer. HPV induces different grades of lesions: among them, Atypical squamous cells of undetermined significance are abnormal lesions that could evolve in pre-cancer lesions or spontaneously regress. The mannose binding lectin (MBL) is an innate immunity serum protein also found in cervico-vaginal mucosa, whose expression is known to be affected by polymorphisms in exon 1 and promoter of the MBL2 gene. In the present study the possible association between MBL2 functional polymorphisms and susceptibility to develop atypical squamous cells of undetermined significance was investigated in a group of women from North-East of Italy, stratified for HPV infection status. The MBL2 D and O alleles and the deficient producer combined genotypes, responsible for low MBL production, were more represented among atypical squamous cells of undetermined significance positive women than healthy controls and the results were confirmed when only HPV negative samples were considered. These results suggest a possible involvement of MBL2 functional polymorphisms in atypical squamous cells of undetermined significance susceptibility.

Human lectins and their roles in viral infections

Innate recognition of virus proteins is an important component of the immune response to viral pathogens. A component of this immune recognition is the family of lectins; pattern recognition receptors (PRRs) that recognise viral pathogen-associated molecular patterns (PAMPs) including viral glycoproteins. In this review we discuss the contribution of soluble and membrane-associated PRRs to immunity against virus pathogens, and the potential role of these molecules in facilitating virus replication. These processes are illustrated with examples of viruses including human immunodeficiency virus (HIV), hepatitis C virus (HCV) and Ebola virus (EBOV). We focus on the structure, function and genetics of the well-characterised C-type lectin mannose-binding lectin, the ficolins, and the membrane-bound CD209 proteins expressed on dendritic cells. The potential for lectin-based antiviral therapies is also discussed.

Regulation of gene expression in HBV- and HCV-related hepatocellular carcinoma: integrated GWRS and GWGS analyses

OBJECTIVES

To explore the molecular mechanism of hepatitis B virus-related and hepatitis C virus-related hepatocellular carcinoma, samples from hepatitis B virus and hepatitis C virus infected patients and the normal were compared, respectively.

METHODS

In both experiments, genes with high value were selected based on a genome-wide relative significance and genome-wide global significance model. Co-expression network of the selected genes was constructed, and transcription factors in the network were identified. Molecular complex detection algorithm was used to obtain sub-networks.

RESULTS

Based on the new model, the top 300 genes were selected. Co-expression network was constructed and transcription factors were identified. We obtained two common genes FCN2 and CXCL14, and two common transcription factors RFX5 and EZH2. In hepatitis B virus experiment, cluster 1 and 3 had the higher value. In cluster 1, ten of the 17 genes and one transcription factor were all reported associated with hepatocellular carcinoma. In cluster 3, transcription factor ESR1 was reported related with hepatocellular carcinoma. In hepatitis C virus experiment, the value of cluster 3 and 4 was higher. In cluster 3, nine genes were reported to play a key role in hepatocellular carcinoma. In cluster 4, there were 5 genes in the 34 genes. To compare the relevance of a node in holding together communicating nodes, centralities based analysis was performed and we obtained some genes with high stress value.

CONCLUSION

The analysis above helped us to understand the pathogenesis of hepatitis B virus and hepatitis C virus associated hepatocellular carcinoma.

A genome-wide detection of copy number variation using SNP genotyping arrays in Beijing-You chickens

Copy number variation (CNV) has been recently examined in many species and is recognized as being a source of genetic variability, especially for disease-related phenotypes. In this study, the PennCNV software, a genome-wide CNV detection system based on the 60 K SNP BeadChip was used on a total sample size of 1,310 Beijing-You chickens (a Chinese local breed). After quality control, 137 high confidence CNVRs covering 27.31 Mb of the chicken genome and corresponding to 2.61 % of the whole chicken genome. Within these regions, 131 known genes or coding sequences were involved. Q-PCR was applied to verify some of the genes related to disease development. Results showed that copy number of genes such as, phosphatidylinositol-5-phosphate 4-kinase II alpha, PHD finger protein 14, RHACD8 (a CD8α- like messenger RNA), MHC B-G, zinc finger protein, sarcosine dehydrogenase and ficolin 2 varied between individual chickens, which also supports the reliability of chip-detection of the CNVs. As one source of genomic variation, CNVs may provide new insight into the relationship between the genome and phenotypic characteristics.

Mannose-binding lectin and ficolin-2 do not influence humoral immune response to hepatitis B vaccine

BACKGROUND

Host genetics appear to be an important factor in the failure to generate a protective immune response after hepatitis B (HBV) vaccination. Mannose-binding lectin (MBL) and ficolin-2 (FCN2), two pattern recognition receptors of the lectin pathway of complement, influence the clinical outcome of HBV, and MBL deficiency has been shown to augment the humoral response to HBV vaccination in several experimental models. Here, we investigated the association of MBL and FCN2 with the humoral response to HBV vaccination in a candidate gene and functional study.

PATIENTS AND METHODS

A post hoc analysis of a prospective, interventional HBV vaccination study among human immunodeficiency virus type 1 (HIV-1) uninfected individuals in Kenya was conducted. Serum levels and polymorphisms of MBL and FCN2 were analysed in relation to the immune response to HBV vaccination.

RESULTS

Protective hepatitis B surface antibody levels (≥ 10 mI U/mL) were evident in 251/293 (85.7%) individuals. Median MBL and FCN2 levels were similar in responders vs. non-responders with a weak trend towards lower median MBL levels in non-responders (1.0 vs. 1.6μg/mL, p=0.1). Similarly, there was no difference in four MBL and six FCN2 polymorphisms analysed in the two groups with the exception of an increased frequency of a homozygous MBL codon 57 mutation in non-responders (4 (9.5%) vs. 8 (3.2%), p=0.05) corresponding to lower MBL levels. Results were similar after adjusting for age and sex.

CONCLUSIONS

Our study does not support a prominent role of the lectin pathway of complement in general and MBL and FCN2 in particular in the humoral immune response to HBV vaccination in African adults.

The lectin pathway of complement: advantage or disadvantage in HIV pathogenesis?

The pattern recognition molecules of the lectin complement pathway are important components of the innate immune system with known functions in host-virus interactions. This paper summarizes current knowledge of how these intriguing molecules, including mannose-binding lectin (MBL), Ficolin-1, -2 and -3, and collectin-11 (CL-11) may influence HIV-pathogenesis. It has been demonstrated that MBL is capable of binding and neutralizing HIV and may affect host susceptibility to HIV infection and disease progression. In addition, MBL may cause variations in the host immune response against HIV. Ficolin-1, -2 and -3 and CL-11 could have similar functions in HIV infection as the ficolins have been shown to play a role in other viral infections, and CL-11 resembles MBL and the ficolins in structure and binding capacity.

Mannose binding lectin and ficolin-2 polymorphisms are associated with increased risk for bacterial infections in children with B acute lymphoblastic leukemia

BACKGROUND

We aimed to investigate whether the presence of mannose binding lectin (MBL2), ficolin 2 (FCN2) polymorphisms or the combined deficiency significantly influence the risk and subsequently the frequency of chemotherapy-induced bacterial infections in children with B acute lymphoblastic leukemia (B-ALL).

PROCEDURE

MBL2 polymorphisms for exon 1 and FCN2 polymorphisms for promoter regions -986, -602, -557, -64, -4 and exon 8 regions +6,359, +6,424 were determined in children with B-ALL. FCN2 haplotype was determined by gene sequencing. Number and duration of FN episodes as well as number of bacterial infections were recorded during induction chemotherapy.

RESULTS

Forty-four children with B-ALL (median age 4.3 years, 65.9% males) suffered from 142 FN episodes and 92 bacterial infections (40.2% Gram positive and 59.8% Gram negative). MBL2 low-risk genotype was found in 59.1%, medium-risk in 31.8% and high-risk in 9%. FCN2 low-risk haplotypes were detected in 38.2%, medium-risk in 44.1% and high-risk in 17.6%. MBL2 genotype and FCN2 haplotype were not associated with increased frequency of FN episodes. MBL2 medium/high-risk genotype and FCN2 medium/high-risk haplotype were associated with prolonged duration of FN (P = 0.007 and P = 0.001, respectively) and increased number of bacterial infections (P = 0.001 and P = 0.002, respectively). The combined MBL2/FCN2 medium/high-risk genotype was associated with an increased number of bacterial infections (P = 0.001).

CONCLUSIONS

MBL2 and FCN2 single or combined deficiencies are associated with increased duration of FN episodes as well as increased number of bacterial infections in children with B-ALL suggesting a prognostic role of these genes.

Mannose binding lectin and susceptibility to rheumatoid arthritis in Brazilian patients and their relatives

Introduction

Rheumatoid arthritis (RA) is a commonly occurring systemic inflammatory auto immune disease and is believed to be associated with genetic factors. The innate immune complement protein Mannose binding lectin (MBL) and their MBL2 genetic variants are associated with different infectious and autoimmune diseases.

Methods

In a Brazilian cohort, we aim to associate the functional role of circulating MBL serum levels and MBL2 variants in clinically classified patients (n = 196) with rheumatoid arthritis including their relatives (n = 200) and ethnicity matched healthy controls (n = 200). MBL serum levels were measured by ELISA and functional MBL2 variants were genotyped by direct sequencing.

Results

The exon1+54 MBL2*B variant was significantly associated with an increased risk and the reconstructed haplotype MBL2*LYPB was associated with RA susceptibility. Circulating serum MBL levels were observed significantly lower in RA patients compared to their relatives and controls. No significant contribution of MBL levels were observed with respect to functional class, age at disease onset, disease duration and/or other clinical parameters such as nodules, secondary Sjögren syndrome, anti-CCP and rheumatoid factor. Differential distribution of serum MBL levels with functional MBL2 variants was observed in respective RA patients and their relatives.

Conclusions

Our results suggest MBL levels as a possible marker for RA susceptibility in a Brazilian population.

Ficolins and infectious diseases

Ficolins are serum complement lectins, with a structure similar to mannose-binding lectin (MBL) and lung surfactant protein (SP)-A and SP-D. Ficolins activate the lectin complement system and play important roles in host innate immunity. Ficolins are members of the collectin family of proteins, which act as pattern recognition receptors (PRRs). They are soluble oligomeric defense proteins with lectin-like activity, and are able to recognize pathogen-associated molecular patterns (PAMPs), which are carbohydrate molecules on the surface of pathogens, and of apoptotic, necrotic, and malignant cells. Upon binding to their specific PAMPs, ficolins may trigger activation of the immune system either (1) by initiating activation of complement via the lectin pathway, (2) by a primitive type of opsonophagocytosis, or (3) by stimulating secretion of the inflammatory cytokines interferon (IFN)-Γ, interleukin (IL)-17, IL-6, and tumor necrosis factor (TNF)-α, and production of nitric oxide (NO) by macrophages, thus limiting the infection and concurrently orchestrating the subsequent adaptive immune response. Recently, a number of reports have shown that dysfunction or abnormal expression of ficolins may play crucial roles in viral and bacterial diseases and in inflammation. This review summarizes the reports on the roles of ficolins in the infectious diseases, and provides insight into ficolins as novel innate immune therapeutic options to treat these diseases.

Hepatitis B virus-induced hepatocellular carcinoma: functional roles of MICA variants

Hepatitis B virus infection is a high-risk factor for hepatocellular carcinoma. The human major histocompatibility complex class I chain-related gene A (MICA) is a ligand of the NKG2D receptor that modulates the NK and T-cell-mediated immune responses and is associated with several diseases. This study determined the effects of MICA polymorphisms during HBV infection and HBV-induced HCC. We conducted a case-controlled study in a Vietnamese cohort and genotyped ten functional MICA polymorphisms including the microsatellite motif in 552 clinically classified hepatitis B virus patients and 418 healthy controls. The serum soluble MICA levels (sMICA) were correlated with MICA variants and liver enzyme levels. We demonstrated a significant contribution of MICA rs2596542G/A promoter variant and nonsynonymous substitutions MICA-129Met/Val, MICA-251Gln/Arg, MICA-175Gly/Ser, triplet repeat polymorphism and respective haplotypes with HBV-induced HCC and HBV persistence. The circulating sMICA levels in HBV patient groups were elevated significantly compared with healthy controls. A significant contribution of studied MICA variants to sMICA levels was also observed. The liver enzymes alanine amino transferase (ALT), aspartate transaminase (AST), total bilirubin and direct bilirubin were positively correlated with sMICA levels suggesting sMICA as a biomarker for liver injury. We conclude that MICA polymorphisms play a crucial role in modulating innate immune responses, tumour surveillance and regulate disease susceptibility during HBV infection.

LRRK2 and RIPK2 variants in the NOD 2-mediated signaling pathway are associated with susceptibility to Mycobacterium leprae in Indian populations

In recent years, genome wide association studies have discovered a large number of gene loci that play a functional role in innate and adaptive immune pathways associated with leprosy susceptibility. The immunological control of intracellular bacteria M. leprae is modulated by NOD2-mediated signaling of Th1 responses. In this study, we investigated 211 clinically classified leprosy patients and 230 ethnically matched controls in Indian population by genotyping four variants in NOD2 (rs9302752A/G), LRRK2 (rs1873613A/G), RIPK2 (rs40457A/G and rs42490G/A). The LRRK2 locus is associated with leprosy outcome. The LRRK2 rs1873613A minor allele and respective rs1873613AA genotypes were significantly associated with an increased risk whereas the LRRK2 rs1873613G major allele and rs1873613GG genotypes confer protection in paucibacillary and leprosy patients. The reconstructed GA haplotypes from RIPK2 rs40457A/G and rs42490G/A variants was observed to contribute towards increased risk whereas haplotypes AA was observed to confer protective role. Our results indicate that a possible shared mechanisms underlying the development of these two clinical forms of the disease as hypothesized. Our findings confirm and validates the role of gene variants involved in NOD2-mediated signalling pathways that play a role in immunological control of intracellular bacteria M. leprae.

Ficolin-2 and ficolin-3 in women with malignant and benign ovarian tumours

Ficolins are serum pattern recognition molecules. They have opsonic properties and are able to activate complement via the lectin pathway. This paper reports investigations concerning ficolin-2 and ficolin-3 in ovarian cancer (OC). Their serum levels, single nucleotide polymorphisms of the corresponding FCN2 and FCN3 genes and specific mRNA expression in ovarian sections were investigated in 128 patients suffering from primary OC and 197 controls operated on for reasons other than malignancies. The latter consisted of two reference groups: those with benign tumours (n = 123) and those with normal ovaries (NO) (n = 74). Serum ficolin-2 and ficolin-3 concentrations were higher among patients with malignant disease when compared with either of the reference groups. A significant correlation between ficolin-2 and ficolin-3 concentrations was found, while no correlations with CA125 antigen or CRP were observed. No differences in the frequency of single nucleotide polymorphisms at sites -64, -4 (promoter), +6359, or +6424 (exon 8) (FCN2 gene) nor in the frame-shift mutation 1637delC (FCN3 gene) were found between investigated groups. In contrast to serum concentrations, the expression of FCN2 gene (reported for the first time in ovarian sections) was significantly lower in women with OC in comparison with patients with NO but not with benign ovarian tumours. In case of FCN3 gene, its expression levels in OC group inversely correlated with serum ficolin-3 and were lower in comparison with controls.

A trivial role of STAT4 variant in chronic hepatitis B induced hepatocellular carcinoma

Two polymorphisms in the STAT4 and HLA-DQ loci were more recently reported to associate with chronic hepatitis B (CHB) induced hepatocellular carcinoma (HCC). We utilised an independent Vietnamese cohort of clinically classified HBV patients of chronic hepatitis B carriers (n=206), liver cirrhosis (n=222) and hepatocellular carcinoma (n=239) and assessed the influence of the reported variants. The STAT4 variant (rs7574865) was marginally associated with HCC susceptibility in CHB carriers in allelic and recessive genetic models (OR=0.84, 95%CI=0.7-0.99, P=0.048 and OR=0.7, 95%CI=0.5-0.99, P=0.047). No significant association between the studied variant with several clinical parameters such as liver enzymes (ALT, AST), total and direct bilirubin, AFP, HBV genotype and viral loads were observed. Our study highlights the reported variant to be a trivial factor and possibly other confounding factors may regulate STAT4 expression during HCC development.

Swierzko A, Cedzynski M. Cost-effective procedures for genotyping of human FCN2 gene single nucleotide polymorphisms

L-ficolin (ficolin-2) is a complement-activating pattern-recognition lectin taking part in the innate immune response. Both its serum concentration and sugar binding capacity are influenced by single nucleotide polymorphisms (SNP) of the corresponding FCN2 gene. Cost-effective and simple procedures, based on polymerase chain reaction (PCR) or PCR-restriction fragment length polymorphism for an investigation of four FCN2 SNPs are proposed: -64 A > C (rs7865453), -4 A > G (rs17514136; both located in the promoter region), +6359 C > T (rs17549193), +6424 G > T (rs7851696; both in exon 8). Variant alleles of -64 and +6424 (in strong linkage disequlibrium) are known to be associated with low L-ficolin level or activity. In contrast, variant alleles at positions -4 and +6359 (also in strong linkage disequlibrium) correspond to higher values. Since several L-ficolin clinical associations have been reported, FCN2 genotyping seems to be a valuable tool for disease association studies.

Association of L-ficolin levels and FCN2 genotypes with chronic Chagas disease

BACKGROUND

L-ficolin (encoded by FCN2) binds to acetylated sugar moieties of many pathogens, including Trypanosoma cruzi, promoting their phagocytosis and lysis by the complement system.

METHODS

We investigated L-ficolin levels in 160 T. cruzi infected patients with chronic Chagas disease and 71 healthy individuals, and FCN2 polymorphisms (-986 G>A, -602 G>A, and -4 A>G in the promoter and A258S in exon 8) in 243 patients, being 88 indeterminate (asymptomatic), 96 with cardiac, 23 with digestive and 33 with cardiodigestive manifestations (two were unspecified) and 305 controls (135 for A258S).

RESULTS

Patients presented lower L-ficolin plasma levels than controls (p<0.0001). Among the different groups of cardiac commitment, individuals with moderate forms had higher L-ficolin levels than the severe forms (P = 0.039). Lower L-ficolin levels were found associated with the 258S variant in the patients (P = 0.034). We found less -4A/G heterozygotes in the cardiac patients, than in the controls (OR = 0.56 [95% CI = 0.33-0.94], P = 0.034). Heterozygote -4A/G genotypes with the 258S variant and 258SS homozygotes were nevertheless more frequent among cardiodigestive patients than in controls (OR = 14.1 [95% CI = 3.5-56.8], P = 0.0001) and in indeterminate patients (OR = 3.2 [95% CI = 1.1-9.4], P = 0.037). We also found an association of the allelic frequency of the 258S variant with cardiodigestive Chagas disease compared to controls (OR = 2.24 [95% CI = 1.1-4.5], P = 0.037). Thus, decreased patient levels of L-ficolin reflect not only protein consumption due to the disease process, but also the higher frequency of the 258S variant in patients with cardiodigestive symptoms.

CONCLUSION

The very first study on Brazilian cohort associates both L-ficolin plasma levels and FCN2 variants to Chagas disease and subsequent disease progression. The prognostic value of L-ficolin levels and the FCN2*A258S polymorphism should be further evaluated in other settings.

Early increased ficolin-2 concentrations are associated with severity of liver inflammation and efficacy of anti-viral therapy in chronic hepatitis C patients

Ficolin-2 is a kind of human serum complement lectin with a structure similar to mannan-binding lectin (MBL), and it has been implicated in innate immunity. Recent studies have shown that complement pathway activation may contribute to hepatitis. However, the relationship between ficolin-2 and viral hepatitis remains largely elusive. The aim of this study was to determine the dynamics of ficolin-2 in patients with chronic hepatitis C. Forty nine patients who had not yet received therapy [24 patients with abnormal alanine aminotransferase (ALT) levels (>40 U/L) and 25 patients with normal ALT levels (≤ 40 U/L)], 28 patients with hepatitis C who received therapy for 2 weeks and 16 patients received therapy for a full month or longer were included in the study. A sandwich enzyme-linked immunosorbent assay (ELISA) was used to measure the ficolin-2 concentrations in all serum samples of patients and 42 healthy donors. We found the concentrations of ficolin-2 were significantly higher in chronic hepatitis C patients with abnormal ALT values than in chronic hepatitis C patients with normal ALT values and healthy controls. Ficolin-2 concentrations in chronic hepatitis C patients with abnormal ALT values were positively correlated with ALT levels (P < 0.05). After therapy, the concentrations of ficolin-2 decreased and accompany with ALT and Hepatitis C virus (HCV) RNA levels. Then, we found ficolin-2 concentrations in rapid viral response (RVR) group decreased significantly (P < 0.05), while in non-RVR group, ficolin-2 decreased slightly (P > 0.05). Our findings suggest that early increased ficolin-2 is highly correlated with hepatic inflammation and rapid viral response.

Mice deficient in ficolin, a lectin complement pathway recognition molecule, are susceptible to Streptococcus pneumoniae infection

Mannose-binding lectin (MBL) and ficolin are complexed with MBL-associated serine proteases, key enzymes of complement activation via the lectin pathway, and act as soluble pattern recognition molecules in the innate immune system. Although numerous reports have revealed the importance of MBL in infectious diseases and autoimmune disorders, the role of ficolin is still unclear. To define the specific role of ficolin in vivo, we generated model mice deficient in ficolins. The ficolin A (FcnA)-deficient (Fcna(-/-)) and FcnA/ficolin B double-deficient (Fcna(-/-)b(-/-)) mice lacked FcnA-mediated complement activation in the sera, because of the absence of complexes comprising FcnA and MBL-associated serine proteases. When the host defense was evaluated by transnasal infection with a Streptococcus pneumoniae strain, which was recognized by ficolins, but not by MBLs, the survival rate was significantly reduced in all three ficolin-deficient (Fcna(-/-), Fcnb(-/-), and Fcna(-/-)b(-/-)) mice compared with wild-type mice. Reconstitution of the FcnA-mediated lectin pathway in vivo improved survival rate in Fcna(-/-) but not in Fcna(-/-)b(-/-) mice, suggesting that both FcnA and ficolin B are essential in defense against S. pneumoniae. These results suggest that ficolins play a crucial role in innate immunity against pneumococcal infection through the lectin complement pathway.

Ficolin-2 levels and FCN2 genetic polymorphisms as a susceptibility factor in schistosomiasis

BACKGROUND

Human ficolin-2 (L-ficolins) encoded by the FCN2 gene are pattern-recognition proteins involved in innate immunity and are associated with several infectious diseases.

METHODS

A Nigerian cohort of 168 Schistosoma haematobium-infected individuals and 192 healthy controls were examined for functional single-nucleotide polymorphisms in the promoter region (-986G>A, -602G>A, -4A>G) and in exon 8 (+6424G>T) using real-time polymerase chain reaction.

RESULTS

The FCN2 -986A and -4G alleles were significantly associated with the occurrence of schistosomiasis (P = .0004 for -986G>A; P = .0001 for -4A>G). The heterozygous genotypes (P = .0006 for -986G>A; P = .0002 for -4A>G) were observed to be a risk factor for susceptibility to schistosomiasis, whereas the homozygous genotypes of major alleles (P = .0002 for -986G>A; P = .0001 for -4A>G) were observed to shield against schistosomiasis. The haplotype AGGG (P = .0002) was observed to be a risk factor for susceptibility to schistosomiasis compared with controls, and the haplotype GGAG (P = .04) was observed to confer protection compared with patients. Ficolin-2 serum level was significantly higher in controls (P < .005) and in controls with GGAG haplotypes (P < .0001).

CONCLUSIONS

Our findings demonstrate that FCN2 promoter variants (-986G>A and -4A>G) influence ficolin-2 serum levels and susceptibility to schistosomiasis.

Reliable and rapid characterization of functional FCN2 gene variants reveals diverse geographical patterns

BACKGROUND

Ficolin-2 coded by FCN2 gene is a soluble serum protein and an innate immune recognition element of the complement system. FCN2 gene polymorphisms reveal distinct geographical patterns and are documented to alter serum ficolin levels and modulate disease susceptibility.

METHODS

We employed a real-time PCR based on Fluorescence Resonance Energy Transfer (FRET) method to genotype four functional SNPs including -986 G > A (#rs3124952), -602 G > A (#rs3124953), -4A > G (#rs17514136) and +6424 G > T (#rs7851696) in the ficolin-2 (FCN2) gene. We characterized the FCN2 variants in individuals representing Brazilian (n = 176), Nigerian (n = 180), Vietnamese (n = 172) and European Caucasian ethnicity (n = 165).

RESULTS

We observed that the genotype distribution of three functional SNP variants (-986 G > A, -602 G > A and -4A > G) differ significantly between the populations investigated (p < 0.0001). The SNP variants were highly linked to each other and revealed significant population patterns. Also the distribution of haplotypes revealed distinct geographical patterns (p < 0.0001).

CONCLUSIONS

The observed distribution of the FCN2 functional SNP variants may likely contribute to altered serum ficolin levels and this may depend on the different disease settings in world populations. To conclude, the use of FRET based real-time PCR especially for FCN2 gene will benefit a larger scientific community who extensively depend on rapid, reliable method for FCN2 genotyping.

Genetic evidence of functional ficolin-2 haplotype as susceptibility factor in cutaneous leishmaniasis

BACKGROUND

Ficolin-2 coded by FCN2 gene is a soluble serum protein that plays an important role in innate immunity. In this study, we analyzed five functional polymorphisms of the FCN2 gene for their possible association with cutaneous leishmaniasis.

METHODS

Initially we screened 40 Syrian Arabs for the entire FCN2 gene. We investigated the contribution of FCN2 functional variants in 226 patients with cutaneous leishmaniasis and 286 healthy controls from Syria. Polymorphisms in the promoter regions (-986G/A, -602G/A, -4A/G) of the FCN2 gene were assessed by TaqMan real time PCR, whereas polymorphisms in exon8 (+6359C/T and +6424G/T) were assessed by DNA sequencing. We also measured serum ficolin-2 levels in 70 control Syrian Arabs and correlated the serum concentrations to FCN2 genotypes and haplotypes respectively.

RESULTS

Nine new FCN2 variants including two with non synonymous substitutions in exon6 and exon8 were observed. The homozygous genotypes +6424T/T were distributed more in controls and none in patients (P = 0.04). The AGACG haplotype were observed more in patients than in controls (OR = 2.0, 95%CI 1.2-3.4, P = 0.006). The serum ficolin-2 levels were significantly distributed among the reconstructed ficolin-2 haplotypes (P<0.008) and the haplotype AGACG was observed with higher ficolin-2 levels in 70 control individuals.

CONCLUSION

Our results demonstrate a significant association of FCN2 AGACG haplotype with cutaneous leishmaniasis in a Syrian Arab population. These first results provide a basis for a future study that could confirm or disprove possible relationships between FCN2 gene polymorphisms with cutaneous leishmaniasis.