RESUMO
Deficiency of mannan-binding lectin-associated serine protease 2 (MASP-2) has been associated with infections, whereas high levels appear to increase the risk of inflammatory disorders. Nevertheless, MASP2 haplotypes have been poorly investigated. To overcome haplotyping cost and time consumption, we developed multiplex polymerase chain reactions with sequence-specific primers (PCR-SSP) for 8 single nucleotide polymorphisms (SNPs), reducing the number of necessary reactions from 18 to 7. SNPs were distributed from the promoter to the last exon, and a single PCR-SSP was used for p.D120G. We evaluated the phylogenetic relationships and global distribution of 10 identified haplotypes in 338 Danish individuals with known MASP-2 and MAp19 levels and 309 South Brazilians. Four haplotypes were associated with reduced MASP-2 levels in plasma (lower than 200 ng/mL). Simultaneous association with the highest MASP-2 (over 600 ng/mL) and lowest MAp19 levels (lower than 200 ng/mL) was demonstrated with the intron 9 mutation (Kruskal-Wallis p < 0.0001). Cumulative genotype frequencies predict approximately 0.4% severely deficient and 25% overproducing individuals in both populations. Rapid and low-cost screening of patients with multiplex MASP2 PCR-SSP could be used to identify clinical conditions where MASP-2 (or MAp19) levels may be disease modifying, possibly improving disease outcome through early therapeutic and preventive measures.
Assuntos
Doenças Autoimunes/genética , Etnicidade , Infecções/genética , Serina Proteases Associadas a Proteína de Ligação a Manose/metabolismo , Processamento Alternativo/genética , Biomarcadores/metabolismo , Brasil/etnologia , Dinamarca/epidemiologia , Frequência do Gene , Predisposição Genética para Doença , Haplótipos , Ensaios de Triagem em Larga Escala , Humanos , Serina Proteases Associadas a Proteína de Ligação a Manose/genética , Reação em Cadeia da Polimerase Multiplex , Filogenia , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Hepatitis C virus (HCV) is a major cause of hepatic disease and of liver transplantation worldwide. Mannan-binding lectin (MBL), encoded by the MBL2 gene, can have an important role as an opsonin and complement activating molecule in HCV persistence and liver injury. We assessed the MBL2 polymorphism in 102 Euro-Brazilian patients with moderate and severe chronic hepatitis C, paired for gender and age with 102 HCV seronegative healthy individuals. Six common single nucleotide polymorphisms in the MBL2 gene, three in the promoter (H/L, X/Y and P/Q) and three in exon 1 (A, the wild-type, and B, C or D also known as O) were evaluated using real-time polymerase chain reaction with fluorescent hybridization probes. The concentration of MBL in plasma was measured by enzyme-linked immunosorbent assay. The frequency of the YA/YO genotype was significantly higher in the HCV patients compared with the controls (P = 0.022). On the other hand, the genotypes associated with low levels of MBL (XA/XA, XA/YO and YO/YO) were decreased significantly in the patients with severe fibrosis (stage F4), when compared with the patients with moderate fibrosis (stage F2) (P = 0.04) and to the control group (P = 0.011). Furthermore, MBL2 genotypes containing X or O mutations were found to be associated with non-responsiveness to pginterferon and ribavirin treatment (P = 0.023). MBL2 polymorphisms may therefore be associated not only with the development of chronic hepatitis C, but also with its clinical evolution and response to treatment.
Assuntos
Antivirais/uso terapêutico , Hepatite C Crônica/genética , Interferon-alfa/uso terapêutico , Cirrose Hepática/virologia , Lectina de Ligação a Manose/genética , Adulto , Feminino , Predisposição Genética para Doença , Genótipo , Hepatite C Crônica/sangue , Hepatite C Crônica/tratamento farmacológico , Humanos , Cirrose Hepática/genética , Masculino , Lectina de Ligação a Manose/sangue , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Índice de Gravidade de Doença , Resultado do TratamentoRESUMO
Mannan-binding lectin (MBL) and ficolins distinguish between self, non-self and altered-self by recognizing patterns of ligands on the surface of microorganisms or aberrant cells. When this happens MBL-associated serine protease-2 (MASP-2) is activated and cleaves complement factors to start inflammatory actions. We examined human populations for MASP-2 levels, MASP-2 function and for the presence of mutations in coding exons of MASP2. The MASP-2 levels were lowest in Africans from Zambia (median, 196 ng/ml) followed by Hong Kong Chinese (262 ng/ml), Brazilian Amerindians (290 ng/ml) and Danish Caucasians (416 ng/ml). In the Chinese population, we uncovered a novel four amino-acid tandem duplication (p.156_159dupCHNH) associated with low levels of MASP-2. The frequency of this mutation as well as the SNPs p.R99C, p.R118C, p.D120G, p.P126L and p.V377A were analyzed. The p.156_159dupCHNH was only found in Chinese (gene frequency 0.26%) and p.D120G was found only in Caucasians and Inuits from West-Greenland. The p.P126L and p.R99Q were present in Africans and Amerindians only, except for p.R99Q in one Caucasian. The MASP-2 levels were reduced in individuals with p.V377A present. The MASP-2 present in individuals homozygous for p.377A or p.99Q had a normal enzyme activity whereas MASP-2 in individuals homozygous for p.126L was non-functional.