Association between early onset and organ manifestations of systemic lupus erythematosus (SLE) and a down-regulating promoter polymorphism in the MBL2 gene

Clinical Features of ANCA-Associated Vasculitis in African American Patients in the United States: A Single-Center Medical Records Review Study

BACKGROUND/PURPOSE

The aim of this study was to compare the clinical features at presentation of ANCA-associated vasculitis (AAV) between African American (AA) and White patients.

METHODS

This is a chart review of cases between January 2003 and December 2018. African American patients with AAV were identified and matched in a 1:2 ratio with White comparators based on the year of diagnosis (±4 years). Data on demographics, clinical, and laboratory features and outcomes at presentation were collected. Descriptive statistics were used to compare the characteristics between groups.

RESULTS

Thirty-two of 56 AA patients with AAV had complete data and were included for analysis. When compared with 64 matched White patients with AAV, AA patients were younger (47.5 vs 61.0 years, p = 0.001). Compared with White patients, AA patients with granulomatosis with polyangiitis (GPA) (35 vs 55 years, p = 0.0006) and microscopic polyangiitis (MPA) (55.5 vs 65.0 years, p = 0.05) were younger. African American patients with GPA were more frequently female (p = 0.008), whereas AA patients with MPA were more frequently male (p = 0.03). No differences in disease manifestations, disease activity, and outcomes were observed between AA and White patients with AAV.

CONCLUSIONS

In this single-center study, AA patients with AAV were diagnosed at a younger age than Whites; this was found in both the GPA and MPA disease phenotypes. No other significant differences were observed. Future studies are needed to confirm our findings and better describe differences of AAV in racial/ethnic minorities.

Association between complement gene polymorphisms and systemic lupus erythematosus: a systematic review and meta-analysis

Complement dysfunction results in impaired ability in clearing apoptotic cell debris that may stimulate autoantibody production in systemic lupus erythematosus (SLE). Herein, we provided a comprehensive search to find and meta-analyze any complement gene polymorphisms associated with SLE. The ITGAM, C1q, and MBL gene polymorphisms were included in this meta-analysis to reveal the exact association with SLE risk. Electronic databases, including Scopus, PubMed, and Google Scholar, were searched to find studies investigating the ITGAM, C1q, and MBL gene polymorphisms and SLE risk in different populations. The pooled odds ratio (OR) and its corresponding 95% confidence interval (CI) were used to analyze the association between ITGAM, C1q, and MBL gene polymorphisms and susceptibility to SLE. According to inclusion criteria, a total of 24 studies, comprising 4 studies for C1QA rs292001, 5 studies for C1QA rs172378, 9 studies for ITGAM rs1143679, 8 studies for MBL rs1800450, 3 studies for MBL2 rs1800451, and 3 studies for MBL2 rs5030737, were included in the final meta-analysis. A significant positive association was found between rs1143679 and SLE risk, while rs1800451 significantly associated with decreased SLE susceptibility. In summary, ITGAM gene rs1143679 SNP and MBL gene rs1800451 SNP were positively and negatively associated with SLE risk, respectively.

Systemic Lupus Erythematosus in Children and Young People

PURPOSE OF REVIEW

Juvenile-onset systemic lupus erythematosus ((j)SLE) is an autoimmune/inflammatory disease that results in significant damage and disability. When compared to patients with disease onset in adulthood, jSLE patients exhibit increased disease activity, damage and require more aggressive treatments. This manuscript summarises age-specific pathogenic mechanisms and underscores the need for age group-specific research, classification and treatment.

RECENT FINDINGS

Genetic factors play a significant role in the pathophysiology of jSLE, as > 7% of patients develop disease as a result of single gene mutations. Remaining patients carry genetic variants that are necessary for disease development, but require additional factors. Increased 'genetic impact' likely contributes to earlier disease onset and more severe phenotypes. Epigenetic events have only recently started to be addressed in jSLE, and add to the list of pathogenic mechanisms that may serve as biomarkers and/or treatment targets. To allow meaningful and patient-oriented paediatric research, age-specific classification criteria and treatment targets require to be defined as currently available tools established for adult-onset SLE have limitations in the paediatric cohort. Significant progress has been made in understanding the pathophysiology of jSLE. Meaningful laboratory and clinical research can only be performed using age group-specific tools, classification criteria and treatment targets.

Association of MBL2 gene polymorphisms and systemic lupus erythematosus susceptibility: A meta-analysis

OBJECTIVES

Mannose binding lectin (MBL) gene single nucleotide polymorphisms have been associated with systemic lupus erythematosus (SLE) risk with inconsistent results. This study aimed to explore whether MBL2 A\B, A\C, A\D, A\O, L\H and Y\X polymorphisms affected SLE susceptibility.

METHODS

A meta-analysis was performed on 20 studies, containing allelic contrast, additive, dominant and recessive models. Odds ratio (OR) was calculated to reflect the effect of association.

RESULTS

A total of 64 pooled comparisons were conducted, including 7194 SLE patients and 7401 healthy controls. The meta-analysis inducted a significant association between allele B and SLE (OR = 0.766, 95% CI = 0.681-0.862, P < .001). The genotype BB in the additive model and AB + BB in the recessive model both reduced the risk of SLE (OR = 0.611, 95% CI = 0.422-0.882, P = .009; OR = 0.806, 95% CI = 0.688-0.944, P = .008). Regarding A\O polymorphisms, results revealed statistical differences in allelic contrast, additive model and recessive models (OR = 0.826, 95% CI = 0.732-0.931, P = .002; OR = 0.737, 95% CI = 0.557-0.977, P = .034 and OR = 0.793, 95% CI = 0.683-0.921, P = .002, respectively). As for L\H, meta-analysis revealed that allele H and genotype HH both decreased SLE susceptibility in allelic contrast and dominant models (OR = 1.463, 95% CI = 1.097-2.007, P = .018; OR = 1.383, 95% CI = 1.124-1.701, P = .002). Stratification by ethnicity indicated that allele H related to SLE in European populations (OR = 0.736, 95% CI = 0.617-0.879, P = .001), and the recessive model correlated with SLE in Asians (OR = 0.808, 95% CI = 0.667-0.979, P = .03).

CONCLUSION

The present study suggests that A\B and A\O polymorphisms were associated with SLE susceptibility, and the allele H may be a protective factor in SLE.

The association of mannose binding lectin genotype and immune response to Chlamydia pneumoniae: The Strong Heart Study

Cardiovascular disease (CVD) is an important contributor to morbidity and mortality in American Indian communities. The Strong Heart Study (SHS) was initiated in response to the need for population based estimates of cardiovascular disease in American Indians. Previous studies within SHS have identified correlations between heart disease and deficiencies in mannose binding lectin (MBL), a motif recognition molecule of the innate immune system. MBL mediates the immune response to invading pathogens including Chlamydia pneumoniae (Cp), which has also been associated with the development and progression of CVD. However, a link between MBL2 genotype and Cp in contributing to heart disease has not been established. To address this, SHS collected baseline Cp antibody titers (IgA and IgG) and MBL2 genotypes for common functional variants from 553 individuals among twelve participating tribes. A single nucleotide polymorphism (SNP) in the promoter, designated X/Y, correlated significantly with increased Cp IgG titer levels, whereas another promoter SNP (H/L) did not significantly influence antibody levels to Cp. Two variants within exon 1 of MBL2, the A and B alleles, also displayed significant association with Cp antibody titers. Some MBL2 genotypes were absent from the population, suggesting linkage disequilibrium may be operating within the SHS cohort. Additional factors, such as increasing age and socioeconomic status, were also associated with increased Cp IgG antibody titers. This study demonstrates that MBL2 genotype associates with immune reactivity to C. pneumoniae in the SHS cohort. Thus, MBL2 may contribute to the progression of cardiovascular disease (CVD) among American Indians indirectly through pathogen interactions in addition to its previously defined roles.

Cell death in the pathogenesis of systemic lupus erythematosus and lupus nephritis

Nephritis is one of the most severe complications of systemic lupus erythematosus (SLE). One key characteristic of lupus nephritis (LN) is the deposition of immune complexes containing nucleic acids and/or proteins binding to nucleic acids and autoantibodies recognizing these molecules. A variety of cell death processes are implicated in the generation and externalization of modified nuclear autoantigens and in the development of LN. Among these processes, apoptosis, primary and secondary necrosis, NETosis, necroptosis, pyroptosis, and autophagy have been proposed to play roles in tissue damage and immune dysregulation. Cell death occurs in healthy individuals during conditions of homeostasis yet autoimmunity does not develop, at least in part, because of rapid clearance of dying cells. In SLE, accelerated cell death combined with a clearance deficiency may lead to the accumulation and externalization of nuclear autoantigens and to autoantibody production. In addition, specific types of cell death may modify autoantigens and alter their immunogenicity. These modified molecules may then become novel targets of the immune system and promote autoimmune responses in predisposed hosts. In this review, we examine various cell death pathways and discuss how enhanced cell death, impaired clearance, and post-translational modifications of proteins could contribute to the development of lupus nephritis.

Mannose binding lectin polymorphisms in systemic lupus erythematosus in Spain

Low mannose binding lectin (MBL) producer genotypes have been considered as a systemic lupus erythematosus (SLE) risk factor. The aim of this study was to explore whether polymorphisms in the MBL gene are associated with susceptibility to SLE and disease-specific clinical manifestations or with disease severity in SLE patients in Son Llàtzer Hospital. MBL2 exon 1 and promoter polymorphisms were genotyped and MBL plasma levels were quantified by ELISA in 39 SLE cases and in 96 healthy controls. High MBL producer genotypes HYPA and LXPA were the most frequent haplotypes (65 and 62 participants, respectively). LYQC/HYPD, LXPA/LYQC and LYPB/HYPD were only found in SLE, and all of them were related to severe MBL deficiency. SLE patients showed a trend towards more severe MBL deficiency (MBL <100 ng/mL) compared to controls (10 [25.6%] and 11 [11.46%] respectively, P = 0.07). The wild-type genotype was more frequent in controls compared to SLE. The trend towards more severe MBL deficiency in SLE and the fact that some of the low-MBL producer genotypes were only found in SLE patients, suggest that low MBL levels or MBL2 variant could be a risk factor for the development of SLE.

Genetic Variants That Are Associated with Neuropsychiatric Systemic Lupus Erythematosus

OBJECTIVE

While genetic risks have been implicated in systemic lupus erythematosus (SLE), the involvement of various genotypes in neuropsychiatric SLE (NPSLE) remains uncertain. The present metaanalysis aimed to combine data from different studies and evaluate the association between each genotype and the risk of developing NPSLE.

METHODS

Studies were searched and retrieved from online databases (PubMed, EMBASE, BIOSIS, and ScienceDirect). Case-control studies were chosen if they reported genotype frequencies of the γ Fc region (FCγR) receptors II-A, III-A, and III-B; tumor necrosis factor-α (TNF-α); mannan-binding lectin (MBL); integrin alpha M (ITGAM); interleukin (IL) 1, IL-1β, and IL-6; IL-10 promoter; and vitamin D genes. The OR were used to assess the strength of this association between patients with NPSLE and SLE.

RESULTS

A total of 33 studies were considered in this metaanalysis. The results suggest that these genotypes demonstrated a significant association with NPSLE: the homozygous FCγR IIIa 158 FF genotype (OR 1.89, p = 0.03 for FF vs VV + FV), heterozygous FCγR IIIb NA1/2 genotype (OR 2.14, p = 0.03 for NA1/2 vs NA1/1; OR 1.81, p = 0.04 for NA1/2 vs NA1/1 + NA2/2), and homozygous ITGAM rs1143679 HH genotype (OR 3.39, p = 0.04 for HH vs RH; OR 3.11, p = 0.048 for HH vs RR + RH). Polymorphisms of the TNF-α, MBL2, IL-1, IL-1β, IL-6, IL-10 promoter, and vitamin D receptor genes did not show a statistically significant association with the risk of developing NPSLE (p > 0.05).

CONCLUSION

This metaanalysis indicates that polymorphisms in the pathways of immune complex clearance, such as the FcγRIIIa, FcγRIIIb, and ITGAM genotypes, are potential susceptibility genes for NPSLE.

Mannose binding lectin: a biomarker of systemic lupus erythematosus disease activity

Introduction

A role for mannose binding lectin (MBL) in autoimmune diseases has been demonstrated earlier and elevated level of MBL has been shown in systemic lupus erythematosus (SLE) patients. In the current study, we investigated MBL as a potential biomarker for disease activity in SLE.

Methods

In a case control study SLE patients (93 females) and 67 age, sex, ethnicity matched healthy controls were enrolled. Plasma MBL levels were quantified by enzyme linked immunosorbent assay (ELISA). Clinical, serological and other markers of disease activity (C3, C4 and anti-dsDNA) were measured by standard laboratory procedures.

Results

Plasma MBL levels were significantly high in SLE patients compared to healthy controls (P < 0.0001). MBL levels were variable in different clinical categories of SLE. Lower levels were associated with musculoskeletal and cutaneous manifestations (P = 0.002), while higher and intermediate MBL levels were significantly associated with nephritis in combination with other systemic manifestations (P = 0.01 and P = 0.04 respectively). Plasma MBL correlated with systemic lupus erythematosus disease activity index (SLEDAI) (P = 0.0003, r = 0.36), anti-dsDNA (P < 0.0001, r = 0.54), proteinuria (P < 0.0001, r = 0.42) and negatively correlated with C3 (P = 0.007, r = -0.27) and C4 (P = 0.01, r = -0.29).

Conclusions

Plasma MBL is a promising marker in the assessment of SLE disease activity.

Association of RANTES and MBL gene polymorphisms with systemic lupus erythematosus: a meta-analysis

The RANTES (regulated on activation normal T cell expressed and secreted) and MBL (mannose binding lectin) single-nucleotide polymorphisms have been repeatedly associated with systemic lupus erythematosus (SLE), but the findings are not consistent across studies. The aim of this study was to determine whether the functional RANTES-28, -403 and MBL2 A/O polymorphisms confer susceptibility to SLE in multiple ethnic populations. A meta-analysis was conducted (allelic contrast, the additive model, the dominant model and the recessive model) on RANTES with seven studies (four studies for RANTES-28: three Asian and one American studies; three studies for RANTES-403: two Asian and one European studies), MBL with eight studies (five European and three American studies). OR is used as a measure of the effect of the association in a fixed/random effects model. The meta-analysis indicated that none of the two polymorphisms in gene of the RANTES showed any significant association with SLE risk, respectively, except for the recessive model (OR = 1.24, 95 % CI: 1.01-1.52, P = 0.04) in all study subjects combined with the two polymorphisms. According to the MBL2 A/O polymorphism, the results indicated a significant association between the polymorphism and SLE in allelic contrast (OR = 0.83, 95 % CI: 0.73-0.93, P = 0.002). While stratified by ethnicity in European, no significant association was found. In summary, the present study suggests that the RANTES-28, -403 polymorphisms do not associate with SLE, but the MBL2 A/O polymorphism might associate with SLE.

Low producer MBL genotypes are associated with susceptibility to systemic lupus erythematosus in Odisha, India

Variants of MBL gene have been associated with autoimmune disorders. The aim of this study was to explore whether common polymorphisms in MBL gene are associated with susceptibility to systemic lupus erythematosus (SLE) and its clinical manifestations in a cohort from eastern India. A total of 108 female SLE patients and 105 age, sex, and ethnically matched healthy controls were enrolled in the study. MBL2 codon and promoter polymorphisms were genotyped by AS-PCR and dARMS PCR, respectively. Plasma level of MBL was quantified by ELISA. Higher frequency of BB genotype and minor allele (B) was observed in patients of SLE compared to healthy controls (BB genotype: P = 0.0002; OR = 5.75, 95% CI = 2.09-15.76, B allele: P < 0.0001; OR = 2.78, 95% CI = 1.66-4.64). MBL codon 54, H-550L, Y-221X polymorphisms and combined MBL genotypes contributed to plasma MBL levels. Prevalence of MBL low producer genotype (LXA/LYB, LYB/LYB and LXB/LXB) was significantly higher in SLE patients compared to healthy control. (P = 0.005; OR = 3.09, 95% CI = 1.38-6.91). On analysis of clinical manifestations, MBL low producer genotype was significantly associated with autoimmune haemolytic anaemia (P = 0.006; OR = 13.06). Results of the present study indicate MBL2 variants as possible risk factors for development of SLE and clinical manifestation in eastern India.

Association of MIF-173G/C and MBL2 codon 54 gene polymorphisms with rheumatoid arthritis: a meta-analysis

The aim of this study was to evaluate the association between macrophage migration inhibitory factor (MIF) -173G/C (rs755622), mannose-binding lectin (MBL2) exon 1 codon 54 (rs1800450) gene polymorphisms and rheumatoid arthritis (RA) susceptibility in ethnically different populations. A meta-analysis was conducted (allelic contrast, the additive model, the dominant model and the recessive model) on the MIF-173G/C polymorphism across five studies (four European and one Asian studies), and the MBL2 codon 54 polymorphism with five studies (four Asian and one European studies), respectively. Meta-analysis indicated an association between the MIF-173G/C in all study subjects in allelic contrast (OR=1.19, 95%CI: 1.05-1.35, P=0.001), the additive model (OR=1.68, 95CI: 1.13-2.49, P=0.001), the dominant model (OR=1.17, 95CI: 1.01-1.35, P=0.003), the recessive model (OR=1.63, 95CI: 1.10-2.42, P=0.001). While stratified by ethnicity with European populations, an association was found in allelic contrast (OR=1.20, 95CI: 1.04-1.38, P=0.002), the additive model (OR=1.85, 95CI: 1.19-2.88, P=0.001), the dominant model (OR=1.20, 95CI: 1.02-1.41, P=0.003). With respect to MBL2 codon 54 polymorphism and RA, no association was found in all study subjects in all comparisons, but there was an association while stratified by ethnicity with Asian populations in the dominant model (OR=1.50, 95CI: 1.01-2.23, P=0.007). In conclusion, the present study suggests that the MIF-173G/C polymorphism is associated with RA susceptibility, but the MBL2 codon 54 polymorphism is not associated with RA.

Relevance of the lectin pathway of complement in rheumatic diseases

Due to its importance both in the clearance of pathogens that contribute as rheumatic etiological agents and in the disposal of apoptotic bodies and potential autoimmune initiators, deficiencies of the components of the lectin pathway of complement have been found to increase susceptibility and modulate the severity of most rheumatic disorders. This chapter introduces the general aspects of the structure, function, and genetics of lectin pathway components and summarizes current knowledge of the field regarding rheumatic diseases predisposition and modulation.

How does age at onset influence the outcome of autoimmune diseases?

The age at onset refers to the time period at which an individual experiences the first symptoms of a disease. In autoimmune diseases (ADs), these symptoms can be subtle but are very relevant for diagnosis. They can appear during childhood, adulthood or late in life and may vary depending on the age at onset. Variables like mortality and morbidity and the role of genes will be reviewed with a focus on the major autoimmune disorders, namely, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), type 1 diabetes mellitus (T1D), Sjögren's syndrome, and autoimmune thyroiditis (AITD). Early age at onset is a worst prognostic factor for some ADs (i.e., SLE and T1D), while for others it does not have a significant influence on the course of disease (i.e., SS) or no unanimous consensus exists (i.e., RA and MS).

Association of PPP2CA polymorphisms with systemic lupus erythematosus susceptibility in multiple ethnic groups

OBJECTIVE

T cells from patients with systemic lupus erythematosus (SLE) express increased amounts of PP2Ac, which contributes to decreased production of interleukin-2 (IL-2). Because IL-2 is important in the regulation of several aspects of the immune response, it has been proposed that PP2Ac contributes to the expression of SLE. This study was designed to determine whether genetic variants of PPP2AC are linked to the expression of SLE and specific clinical manifestations and account for the increased expression of PP2Ac.

METHODS

We conducted a trans-ethnic study of 8,695 SLE cases and 7,308 controls of 4 different ancestries. Eighteen single-nucleotide polymorphisms (SNPs) across PPP2CA were genotyped using an Illumina custom array. PPP2CA expression in SLE and control T cells was analyzed by real-time polymerase chain reaction.

RESULTS

A 32-kb haplotype comprising multiple SNPs of PPP2CA showed significant association with SLE in Hispanic Americans, European Americans, and Asians, but not in African Americans. Conditional analyses revealed that SNP rs7704116 in intron 1 showed consistently strong association with SLE across Asian, European American, and Hispanic American populations (odds ratio 1.3 [95% confidence interval 1.14-1.31], meta-analysis P=3.8×10(-7)). In European Americans, the largest ethnic data set studied, the risk A allele of rs7704116 was associated with the presence of renal disease, anti-double-stranded DNA, and anti-RNP antibodies. PPP2CA expression was ∼2-fold higher in SLE patients carrying the rs7704116 AG genotype than those carrying the GG genotype (P=0.007).

CONCLUSION

Our data provide the first evidence of an association between PPP2CA polymorphisms and elevated PP2Ac transcript levels in T cells, which implicates a new molecular pathway for SLE susceptibility in European Americans, Hispanic Americans, and Asians.

Mannose binding lectin gene (MBL2) functional polymorphisms are associated with systemic lupus erythematosus in southern Brazilians

Susceptibility to systemic lupus erythematosus (SLE) has been associated with immunologic, environmental, and genetic factors. To uncover a possible association between MBL2 gene polymorphisms and SLE, we analyzed functional polymorphisms in the promoter and first exon of the MBL2 gene in 134 Brazilian SLE patients and 101 healthy controls. Genotype and allele frequencies of MBL2 A/O polymorphism were significantly different between patients and controls, and the O allele was associated with an increased risk of SLE. An association between low mannose binding lectin (MBL) producer combined genotypes and increased risk for SLE was also reported. Furthermore, when stratifying SLE patients according to clinical and laboratory data, an association between the A/O genotype and nephritic disorders and between the X/Y genotype and antiphospholipid syndrome was evident. Combined genotypes responsible for low MBL production were more frequently observed in SLE patients with nephritis. Our results indicate MBL2 polymorphisms as possible risk factors for SLE development and disease-related clinical manifestations.

Mannose-binding lectin gene polymorphisms in Brazilian patients with systemic lupus erythematosus

The mannose-binding lectin gene (MBL-2) has emerged as a candidate for systemic lupus erythematosus susceptibility, but studies in Brazilian population have not been conducted. To examine potential associations of mannose-binding lectin alleles G57E, G54D, IVSnt5, R52C and R52H with susceptibility to and clinical expression of systemic lupus erythematosus in southern Brazilian patients, we conducted a case—control study with 327 consecutive patients with diagnosis of systemic lupus erythematosus and 345 healthy controls. Genotyping was performed by restriction fragment length polymorphism—polymerase chain reaction assay. A statistically significant difference in the frequencies of allele R52C was observed in European-derived systemic lupus erythematosus patients when compared with controls (9.6% vs. 3.3%, p < 0.001, odds ratio: 3.15, 95% confidence interval: 1.76—5.62, p < 0.05). The frequencies of alleles G54D and G57E were not different between European-derived systemic lupus erythematosus patients and controls. There were no differences between clinical and laboratory features in systemic lupus erythematosus patients according to the presence or absence of mannose-binding lectin allelic variants. These results support an increased risk of systemic lupus erythematosus in European-derived individuals carrying allele R52C. Patients carrying this allele have an approximately three-fold higher odds ratio of developing systemic lupus erythematosus when compared with controls. Our data do not support associations between the mannose-binding lectin allelic variants studied and clinical expression of systemic lupus erythematosus. Lupus (2010) 19, 280—287.

Structural polymorphisms in the mannose-binding lectin gene are associated with juvenile idiopathic arthritis

OBJECTIVE

To investigate the possible association between polymorphisms of the mannose-binding lectin gene (MBL2) and susceptibility to juvenile idiopathic arthritis (JIA).

METHODS

We performed a case-control association study including 118 Hungarian patients with JIA and 118 sex-matched healthy controls. MBL genotyping for the 3 mutant structural alleles at codons 54 (B), 57 (C), and 52 (D) in exon 1 and the promoter polymorphisms at position -550 (HL) and -221 (YX) were carried out by real-time PCR allelic discrimination. Serum level of MBL was determined by ELISA.

RESULTS

Variant allele frequencies of both codon 52 and 57 polymorphisms in the MBL2 gene were significantly overrepresented in JIA (p=0.001 and p=0.004, respectively). The frequency of low MBL genotypes (XA/XA, YA/YO, XA/YO, and YO/YO) in JIA was higher than that in healthy controls (p=0.001). Serum MBL concentrations were found to be significantly lower in JIA patients versus control subjects (p=0.001). The 2 promoter polymorphisms and codon 54 SNP of the MBL2 gene were not associated with JIA.

CONCLUSION

Our findings suggest that genetically determined low MBL levels may predispose children to JIA in a Hungarian population. These data warrant further research to investigate the role of the lectin-dependent complement system in the pathogenesis of JIA.

Lack of association of mannose-binding lectin gene polymorphisms with development and clinical manifestations of systemic lupus erythematosus in Chinese children

Mannose-binding lectin (MBL) gene polymorphisms may be associated with adult-onset systemic lupus erythematosus (SLE), but studies in children with SLE are rare. This study tested the genetic association between MBL polymorphisms and paediatric-onset SLE in a cohort of Chinese children in Taiwan. In all 150 children with SLE and 100 healthy controls of comparable age were genotyped for codon 52, 54 and 57 mutations of the MBL gene using a polymerase chain reaction–based assay. Clinical manifestations, organ involvement, disease activity, laboratory characteristics and outcome were recorded and compared between patients with different MBL genotypes. Codon 54 mutation was fairly common in both SLE patients and controls, whereas codon 52 and codon 57 mutations were not detected in our study subjects. No statistically significant differences were found in allele frequencies of the codon 54 mutation between SLE and control groups. Moreover, no association was found between this MBL polymorphism and clinical manifestations, organ involvement, disease activity, laboratory characteristics or outcome of SLE. These results suggest that MBL polymorphisms do not influence susceptibility to paediatric-onset SLE and do not influence clinical manifestations of SLE in Chinese children.

Mannose-binding lectin genetics: from A to Z

MBL (mannose-binding lectin) is primarily a liver-derived collagen-like serum protein. It binds sugar structures on micro-organisms and on dying host cells and is one of the four known mediators that initiate activation of the complement system via the lectin pathway. Common variant alleles situated both in promoter and structural regions of the human MBL gene (MBL2) influence the stability and the serum concentration of the protein. Epidemiological studies have suggested that genetically determined variations in MBL serum concentrations influence the susceptibility to and the course of different types of infectious, autoimmune, neoplastic, metabolic and cardiovascular diseases, but this is still a subject under discussion. The fact that these genetic variations are very frequent, indicates a dual role of MBL. This overview summarizes the current molecular understanding of human MBL2 genetics.

Detrimental effects of mannose-binding lectin (MBL2) promoter genotype XA/XA on HIV-1 vertical transmission and AIDS progression

BACKGROUND

The literature on the involvement of mannose-binding lectin (MBL) in human immunodeficiency virus (HIV) transmission and acquired immunodeficiency syndrome (AIDS) is conflicting. Polymorphisms in the MBL2 gene reduce the level of protein and alter its structure. Thus, we investigated whether MBL2 alleles and plasma concentrations of MBL are associated with perinatal HIV transmission and disease progression.

METHODS

Frequencies of MBL2 allelic variants (B, C, D, and X) were estimated among 345 HIV-exposed children and 147 blood donors. AIDS-free time was evaluated for different MBL2 genotypes and MBL plasma levels. The median duration of follow-up was 96.5 months.

RESULTS

In the Argentinean population, gene frequencies of MBL2 variants were 18%, 15%, and 3% for the X, B, and D alleles, respectively, with no identified C allele. The haplotype XA/XA was associated with an 8-fold risk of acquiring HIV-1 (P= .054; odds ratio [OR], 8.11 [95% confidence interval {CI}, 0.96-67.86]) and almost a 3-fold risk of progression to pediatric AIDS (P= .026; OR, 2.81 [95% CI, 1.14-7.47]). We also found an independent positive correlation between the rate of AIDS progression and MBL plasma concentration (P= .008; OR, 1.28 [95% CI, 1.07-1.55]).

CONCLUSIONS

Our results demonstrate that homozygosity for the MBL2 promoter genotype XA/XA is an important genetic determinant of HIV-1 acquisition through vertical transmission and the pathogenesis of pediatric HIV/AIDS, via a mechanism that remains to be established.