MBL2 gene polymorphisms related to HIV-1 infection susceptibility and treatment response

Human Mannose-binding lectin (MBL) is a protein encoded by MBL2 gene involved in the activation of the lectin-complement pathway. Several studies emphasized the role of MBL2 gene in several infectious diseases' susceptibility, including HIV-1 infection. We aim to investigate the impact of 10 MBL2 gene polymorphisms located in the promoter, 5'UTR and exon 1 regions on HIV-1 physiopathology. The polymorphisms genotyping of 400 individuals, which 200 were HIV-1 positive patients and 200 were controls, was performed by PCR-sequencing. Our results showed that rs503037 and rs1800451 polymorphisms are associated with a high risk of HIV-1 infection susceptibility while rs7096206 and rs11003123 showed a protective effect. A significant association between haplotype CGA and HIV-1 infection susceptibility was also found in the exon 1 region. Moreover, rs11003124, rs7084554, rs36014597 and rs11003123 polymorphisms revealed an association with treatment response outcome as measured by RNA viral load. This study highlights the importance of MBL2 polymorphisms in the modulation of HIV-1 infection susceptibility and the contribution to treatment response outcomes among Moroccan subjects.

Mannose-binding lectin (MBL) in adult patients with inflammatory bowel disease

Inflammatory bowel disease (IBD) refers to disorders associated with progressive inflammatory processes in the gastrointestinal system. IBD consists of two major forms, Crohn's disease (CD), and ulcerative colitis (UC). IBD became a global disease in the 21^st century. Its pathogenesis is still not fully understood. Mannose-binding lectin (MBL) is a pattern-recognising molecule, involved in anti-microbial and anti-cancer immunity. It is able to opsonize microorganisms and abnormal host cells, and to initiate complement activation. The aim of this study was to investigate possible involvement of MBL in inflammatory bowel disease in adults. Forty persons diagnosed with CD and 28 with ulcerative colitis were recruited. The control group consisted of 136 healthy persons. Single nucleotide polymorphisms of the MBL2 gene (localised to both promoter and exon 1) were determined as were serum MBL concentrations. The exon 1 variant alleles and MBL deficiency-associated genotypes were more frequent among patients compared with controls, although this difference was not statistically significant. No differences of MBL levels were found between the major groups. However in MBL2 A/A homozygous IBD patients, the median was significantly higher than in corresponding healthy subjects. That was particularly evident in the case of active Crohn's disease (1493 ng/ml vs. 800 ng/ml, p = 0.021). It may suggest that MBL and MBL-dependent complement activation contributes to excessive inflammation and its adverse effects in the course of CD. It cannot also be excluded that high MBL activity constitutes in some cases part of a multifactorial network conducing to development of CD.

MBL2 gene polymorphisms in HHV-8 infection in people living with HIV/AIDS

Background

Host genetic factors such as MBL2 gene polymorphisms cause defects in the polymerization of MBL protein and result in a functional deficiency and/or in low serum levels that can influence susceptibility to various viral infections. The aim of this study was to estimate the frequency of alleles, genotypes and haplotypes related to -550, -221 and exon 1 polymorphisms of the MBL2 gene and investigate their association with HHV-8 in people living with HIV/AIDS (PLWHA), as well as the impacts on CD4 cell count and HIV viral load in HIV/HHV-8 coinfected and HIV monoinfected patients.

Results

A cross sectional study in PLWHA, with and without HHV-8 infection, exploring associations between different factors, was performed in the outpatient infectious and parasitic diseases clinic at a referral hospital. Genomic DNA extractions from leukocytes were performed using a commercial Wizard^®Genomic DNA Purification kit (Promega, Madison, WI). The promoter region (-550 and -221) was genotyped with the TaqMan system (Applied TaqMan Biosystems^® genotyping Assays), and the structural region (exon1) was genotyped with Express Sybr Greener Supermix kit (Invitrogen, USA). In total, 124 HIV/HHV-8 coinfected and 213 HIV monoinfected patients were analysed. Median TCD4 counts were significantly lower in HIV/HHV-8 coinfected patients, whereas the mean of the first and last viral load of HIV did not present significant difference. There was no difference in frequency between the LL, YY and AA genotypes between the HIV/HHV-8 coinfected or HIV monoinfected patients. However, in a multivariate analysis, coinfected patients with the intermediate expression haplotype of the MBL2 gene had an odds ratio of 3.1-fold (CI = 1.2–7.6) of their last CD4 cell count being below 350 cells/mm³. Among the coinfected individuals, four developed KS and presented the intermediate expression MBL haplotype, with three being HYA/LXA and one being LYA/LYO.

Conclusions

Host genetic factors, such as -550, -221 and exon 1 polymorphisms, can be related to the may modify coinfections and/or to the development clinical manifestations caused by HHV-8, especially in HIV/HHV-8 coinfected patients who present the intermediate expression haplotypes of MBL.

Lack of Association between Mannose-binding Lectin 2 Codons 54 and 57 Gene Polymorphisms and Cervicovaginal Infections in Mexican Women

The mannose-binding lectin (MBL) 2 gene has an important function in the innate immune response and activation of the third pathway of the complement system. Some studies have assessed the association of the MBL2 gene polymorphisms with cervicovaginal infections (CVI); however, there is no information about this association in Mexican women. This study aimed to determine the association between the MBL2 codons 54 and 57 gene polymorphisms with CVI in a sample of Mexican women. Through a cross-sectional study, blood samples and cervicovaginal cultures were obtain from 354 women. MBL2 genotyping was performed by real-time polymerase chain reaction with Taqman probes. Of the 354 women studied, 128 (36.2%) had CVI and 226 (63.8%) were healthy. The frequencies of the C and T variants in codon 54 in women with CVI were 83% and 17%, respectively; whereas the frequencies of these variants in healthy women were 82% and 18%, respectively. The frequencies of variants C/C, C/T, and T/T in women with CVI were 68%, 31%, and 1%, respectively; whereas the frequencies of these variants in healthy women were 68%, 29%, and 3%, respectively. With respect to codon 57, the frequencies of variants C and T were identical in women with CVI and in healthy women (97% and 3%, respectively). The frequencies of variants C/C, C/T, and T/T were identical in women with CVI and in healthy women (94%, 6%, and 0%, respectively). We conclude that MBL2 codons 54 and 57 gene polymorphisms do not associate with CVI in Mexican women.

Mannose-binding lectin: laying the stepping stones from clinical research to personalized medicine

As a key component of the complement system, mannose-binding lectin (MBL) is one of the linchpins of innate immunity. It is, therefore, not surprising that MBL2 genetic variants affecting the quantity and activity of the MBL protein in serum have been associated with increased susceptibility to infection and autoimmune diseases, and with poorer prognostic outcomes. This enhanced risk is particularly the case for children and immunosuppressed patients, especially when immunity is further compromised by coexistent primary or secondary immune deficiencies. In several disease areas, such as sepsis, cystic fibrosis, and recurrent childhood infections, the association between low MBL-producing allelic variants and disease risk and/or severity is particularly strong. It is here that the use of MBL testing and replacement therapy has reached the threshold of personalized medicine. The role of MBL in health and disease, advances in MBL testing methodologies and key areas for possible applications of MBL replacement therapy are reviewed.