FCN2 c.772G>T polymorphism is associated with chronic adenoiditis and/or tonsillitis, but not -4 A>G and -602 G>A

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.

Association of FCN2 polymorphisms and Ficolin-2 levels with dengue fever in Vietnamese patients

BACKGROUND AND OBJECTIVE

The human ficolin-2, encoded by FCN2, recognizes pathogen-associated acetylated residues on their cell surfaces and activates the lectin complement cascade. This study aimed to investigate the contribution of human ficolin-2 and the functional FCN2 genetic variants in dengue virus (DENV) infection and in clinical progression.

METHODS

FCN2 genetic polymorphisms in the promoter, intron 7 and exon 8 were genotyped in 279 patients with dengue fever and in 200 healthy controls by direct Sanger sequencing. The ficolin-2 levels were measured in serum samples by ELISA and correlated with clinical data.

RESULTS

The frequencies of +6031GG, +6220GG and +6424TT genotypes were significantly higher in dengue patients compared to healthy controls indicating an increased risk of dengue fever. The SNPs rs11103563 (+6031A/G), rs7872508 (+6220 T/G), and rs7851696 (+6424G/T) significantly regulated ficolin-2 levels in dengue patients (P < 0.0001). Ficolin-2 levels were increased in patients with dengue and Dengue with Warning Signs (DWS) compared to healthy controls (P < 0.0001 and P = 0.038, respectively). Ficolin-2 levels were significantly increased after 10-14 days of admission in both dengue and DWS patients and then slightly decreased after three weeks of discharge, indicating that ficolin-2 levels were modulated during the progression of dengue fever. In addition, ficolin-2 levels were negatively correlated with AST levels and positively correlated with platelet counts.

CONCLUSIONS

FCN2 polymorphisms are associated with dengue fever in the Vietnamese population. Ficolin-2 levels are modulated during the progression of dengue fever and correlated with clinical parameters and thus may play a possible role in the pathogenesis of DENV infection.

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.