Polymorphisms of the FCN2 Gene 3'UTR Region and Their Clinical Associations in Preterm Newborns.

Katarzyna Sobczuk,Maciej Cedzyński,Mateusz Michalski,Iwona Domżalska-Popadiuk,Hideharu Sekine,Dariusz Jarych,Gabriela Gajek,Maja Kufelnicka-Babout,Karolina Chojnacka,Agnieszka Szala-Poździej,Misao Matsushita,David C Kilpatrick,Anna S Świerzko,Paulina Kobiela,Jarosław Kalinka,Jan Mazela

doi:10.3389/fimmu.2021.741140

Abstract

Ficolin-2 is regarded as an important innate immunity factor endowed with both lectin (carbohydrate recognition) qualities and ability to induce complement activation. The aim of this study was to investigate the association of the FCN2 3’-untranslated region (3’UTR) polymorphisms with ficolin-2 expression and perinatal complications in preterm neonates. The sequencing analysis allowed us to identify six 3’UTR polymorphisms with minor allele frequency (MAF) >1%: rs4521835, rs73664188, rs11103564, rs11103565, rs6537958 and rs6537959. Except for rs4521835, all adhered to Hardy-Weinberg expectations. Moreover, rs6537958 and rs6537959 were shown to be in perfect linkage disequilibrium (LD) with nine other genetic polymorphisms: rs7040372, rs7046516, rs747422, rs7847431, rs6537957, rs6537960, rs6537962, rs11462298 and rs7860507 together stretched on a distance of 1242 bp and very high LD with rs11103565. The 3’UTR region was shown to bind nuclear extract proteins. The polymorphisms at rs4521835 and rs73664188 were found to influence serum ficolin-2 concentration significantly. All polymorphisms identified create (together with exon 8 polymorphism, rs7851696) two haplotype blocks. Among 49 diplotypes (D1-D49) created from rs7851696 (G>T), rs4521835 (T>G), rs73664188 (T>C), rs11103564 (T>C), rs11103565 (G>A) and rs6537959 (T>A), twenty two occurred with frequency >1%. Two diplotypes: D13 (GTTTGT/GGTCGT) and D10 (GTTTGT/GGTCGA), were significantly more frequent among preterm neonates with early onset of infection and pneumonia, compared with newborns with no infectious complications (OR 2.69 and 2.81, respectively; both p<0.05). The minor (C) allele at rs73664188 was associated with an increased risk of very low (≤1500 g) birthweight (OR=1.95, p=0.042) but was associated with the opposite effect at rs11103564 (OR=0.11, p=0.005).

Highlights

Ficolin-2 (L-ficolin) is a serum pattern-recognition molecule, which is able to accelerate clearance of microorganisms directly as an opsonin and indirectly by complement activation via the lectin pathway.Ficolin-2 has been shown to recognise numerous clinically relevant isolates like enteroaggregative Escherichia coli, Aspergillus fumigatus, Mycobacterium tuberculosis, Streptococcus pneumoniae, Staphylococcus aureus and Trypanosma cruzi [1,2,3,4,5]
To identify the polymorphic sites in FCN2 3’-untranslated region (3’UTR) region, in the preliminary experiment the 3183 bp fragment in 75 consecutive DNA samples was analyzed via Sanger sequencing
Ficolin-2 has been associated with a variety of disorders [3, 32, 34, 37,38,39,40,41,42] and proposed as a potential biomarker of certain clinical conditions

Summary

Introduction

Ficolin-2 (L-ficolin) is a serum pattern-recognition molecule, which is able to accelerate clearance of microorganisms directly as an opsonin and indirectly by complement activation via the lectin pathway.Ficolin-2 has been shown to recognise numerous clinically relevant isolates like enteroaggregative Escherichia coli, Aspergillus fumigatus, Mycobacterium tuberculosis, Streptococcus pneumoniae, Staphylococcus aureus and Trypanosma cruzi [1,2,3,4,5]. Ficolin-2 was shown to interact with endogenous factors like elastin, complement CR1 receptor, C-reactive protein (CRP) and long pentraxin 3 [9,10,11,12] and may be involved in the clearance of late apoptotic/necrotic cells [13]. The CRP-ficolin-2 complex, formed under inflammatory conditions, enables a cross-talk between lectin and classical pathways of complement activation that results in enhancement of serum antimicrobial activity [11]. Three splicing variants have been identified: the first variant lacks the second exon sequence and has an additional 76 bp sequence extending from 3’UTR; the second variant is generated by the insertion of the fifth intron and has an additional 3’UTR sequence of 1060 bp; and the third variant is generated by the insertion of both third and fifth introns [14]

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