[Show abstract][Hide abstract] ABSTRACT: Chagas disease (CD) is caused by Trypanosoma cruzi, whose sugar moieties are recognized by mannan binding lectin (MBL), a soluble pattern-recognition molecule that activates the lectin pathway of complement. MBL levels and protein activity are affected by polymorphisms in the MBL2 gene. We sequenced the MBL2 promoter and exon 1 in 196 chronic CD patients and 202 controls. The MBL2*C allele, which causes MBL deficiency, was associated with protection against CD (P = 0.007, OR = 0.32). Compared with controls, genotypes with this allele were completely absent in patients with the cardiac form of the disease (P = 0.003). Furthermore, cardiac patients with genotypes causing MBL deficiency presented less heart damage (P = 0.003, OR = 0.23), compared with cardiac patients having the XA haplotype causing low MBL levels, but fully capable of activating complement (P = 0.005, OR = 7.07). Among the patients, those with alleles causing MBL deficiency presented lower levels of cytokines and chemokines possibly implicated in symptom development (IL9, p = 0.013; PDGFB, p = 0.036 and RANTES, p = 0.031). These findings suggest a protective effect of genetically determined MBL deficiency against the development and progression of chronic CD cardiomyopathy.
[Show abstract][Hide abstract] ABSTRACT: Pemphigus foliaceus (PF) is an autoimmune disease endemic to Brazil characterized by the detachment of epidermal cells from each other (acantholysis) and the presence of autoantibodies, leading to blistering skin lesions. Pathogenesis of PF is multifactorial, with environmental and genetic factors contributing to the disease development. In previous studies of our group, polymorphisms of several immune-related genes have been associated to PF susceptibility; in addition, genome-wide expression profiling revealed numerous genes differentially expressed between patients and healthy controls. Yet, it remains unknown whether epistatic or additive interactions exist between the analyzed genetic variants. The aim of this study was to look for interactions between polymorphisms previously genotyped in PF patients and healthy controls. First, we compiled all genotyped single nucleotide polymorphisms (SNPs) from our database. After quality control, 119 SNPs in 248 cases and 217 controls were analyzed. Further, we performed a stepwise logistic regression in an additive model using sex and ethnicity as covariants. Finally, gene-gene interactions were evaluated. Statistical analysis were performed using PLINK v1.07, considering 95% confidence interval of the odds ratio (OR) and p<0.05 to assess statistical significance. We found seven SNPs individually associated with PF, where the minor allele (MA) of SNP rs1803254 (CD33) was the one associated with most significant susceptibility (OR = 1.520 and p = 0.009), and the MA of rs11052877 (CD69) was associated with most significant protection to PF (OR = 0.650 and p = 0.007). Six of these SNPs interacted with at least one other SNP. Interestingly, two SNPs interacted with two or more SNPs: rs1803254 (CD33) with rs8109405 (NKG7) (OR = 0.310, p = 0.005) and with rs56802430 (LAIR1) (OR = 0.517, p = 0.021); and SNP rs1129055 (CD86) interacted with rs1051065 (CD69) (OR = 0.542, p = 0.017), with rs11084332 (LAIR1) (OR = 1.667, p = 0.028) and with rs12940684 (TNFSF12) (OR = 0.610, p = 0.028). These results indicate biologically relevant functional interactions between variants of immune-related genes regarding pathogenesis of PF and show that the effect of some alleles only appears in presence of allele(s) of other loci. In conclusion, the results of this study point the need of considering gene-gene interactions in search for the missing heritability of complex diseases.
[Show abstract][Hide abstract] ABSTRACT: Objective:
The aim of this study was to investigate the frequency of the LCT*-13910C>T polymorphism associated with high expression of lactase in the small intestine during adulthood and to infer the lactase persistence and adult-type hypolactasia phenotypes among Euro-Brazilians and Mennonites from South Brazil.
Materials (Subjects) and Methods
We developed a sequence-specific PCR method to genotype the LCT*-13910C>T polymorphism in 292 Euro-Brazilians and151 Mennonites, which is a group of European ancestry with a long history of endogamy. Using an exact test of population differentiation, we compared genotype and allele frequency between them and other Brazilian and European populations.
The frequency of -13910*T was significantly higher among Mennonites, compared to Euro-Brazilians (0.63 vs. 0.33, P<0.000001). Accordingly, Mennonites had a higher prevalence of the lactase persistence phenotype (88.1% vs. 55.5%, P<0.000001). The distribution of -13910*T differed between Euro-Brazilian groups from two different regions of Brazil, as well as between our Euro-Brazilian cohort and other populations from Europe. On the other hand, Mennonites differed to all other Euro-descendant groups from Brazil, but had similar frequencies to Central-Europeans.
Differences in -13910*T-associated lactase persistence distribution among Euro-Brazilian groups reflect ancestry and admixture of each particular group and should be considered for adult-type hypolactasia screening.
No preview · Article · Sep 2015 · Medical Principles and Practice
[Show abstract][Hide abstract] ABSTRACT: MASP-2 is a key protein of the lectin pathway of complement system. Several MASP2 polymorphisms were associated with MASP-2 serum levels or functional activity. Here we investigated a possible association between MASP2 polymorphisms and MASP-2 serum levels with the susceptibility to Rheumatic Fever (RF) and Rheumatic Heart Disease (RHD). We haplotyped 11 MASP2 polymorphisms with multiplex sequence-specific PCR in 145 patients with history of RF from south Brazil (103 with RHD and 42 without cardiac lesion [RFo]) and 342 healthy controls. MASP-2 levels were determined by ELISA. The low MASP-2 producing p.377A and p.439H variants were negatively associated with RF (P=0.02, OR=0.36) and RHD (P=0.01, OR=0.25). In contrast, haplotypes that share the intron 9 - exon 12 g.1961795C, p.371D, p.377V and p.439R polymorphisms increased the susceptibility to RHD (P=0.02, OR=4.9). MASP-2 levels were associated with MASP2 haplotypes and were lower in patients (P<0.0001), which may reflect protein consumption due to complement activation. MASP2 gene polymorphisms and protein levels seem to play an important role in the development of RF and establishment of RHD.
No preview · Article · Oct 2014 · Human Immunology
[Show abstract][Hide abstract] ABSTRACT: The innate immune system is the first line of host defense against infection and is comprised of humoral and cellular mechanisms that recognize potential pathogens within minutes or hours of entry. The effector components of innate immunity include epithelial barriers, phagocytes, and natural killer cells, as well as cytokines and the complement system. Complement plays an important role in the immediate response against microorganisms, including Streptococcus sp. The lectin pathway is one of three pathways by which the complement system can be activated. This pathway is initiated by the binding of mannose-binding lectin (MBL), collectin 11 (CL-K1), and ficolins (Ficolin-1, Ficolin-2, and Ficolin-3) to microbial surface oligosaccharides and acetylated residues, respectively. Upon binding to target molecules, MBL, CL-K1, and ficolins form complexes with MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2), which cleave C4 and C2 forming the C3 convertase (C4b2a). Subsequent activation of complement cascade leads to opsonization, phagocytosis, and lysis of target microorganisms through the formation of the membrane-attack complex. In addition, activation of complement may induce several inflammatory effects, such as expression of adhesion molecules, chemotaxis and activation of leukocytes, release of reactive oxygen species, and secretion of cytokines and chemokines. In this chapter, we review the general aspects of the structure, function, and genetic polymorphism of lectin-pathway components and discuss most recent understanding on the role of the lectin pathway in the predisposition and clinical progression of Rheumatic Fever.
Full-text · Article · Sep 2014 · Frontiers in Pediatrics
[Show abstract][Hide abstract] ABSTRACT: Mannan-binding lectin-associated serine protease 2 (MASP-2) is a key protein of the lectin pathway of complement. MASP-2 levels have been associated with different polymorphisms within MASP2 gene as well as with the risk for inflammatory disorders and infections. Despite its clinical importance, MASP-2 remains poorly investigated in rheumatoid arthritis (RA).
In this case-control study, we measured MASP-2 serum levels in 156 RA patients, 44 patient relatives, and 100 controls from Southern Brazil, associating the results with nine MASP2 polymorphisms in all patients, 111 relatives, and 230 controls genotyped with multiplex SSP-PCR.
MASP-2 levels were lower in patients than in controls and relatives (medians 181 vs. 340 or 285 ng/ml, respectively, P<0.0001). Conversely, high MASP-2 levels were associated with lower susceptibility to RA and to articular symptoms independently of age, gender, ethnicity, smoking habit, anti-CCP and rheumatoid factor positivity (OR = 0.05 [95%CI = 0.019-0.13], P<0.0001 between patients and controls; OR = 0.12, [95%CI = 0.03-0.45], P = 0.002 between patients and relatives; OR = 0.06, [95%CI = 0.004-0.73], P = 0.03 between relatives with and without articular symptoms). MASP2 haplotypes *2A1 and *2B1-i were associated with increased susceptibility to RA (OR = 3.32 [95%CI = 1.48-7.45], P = 0.004). Deficiency-causing p.120G and p.439H substitutions were associated with five times increased susceptibility to articular symptoms in relatives (OR = 5.13 [95%CI = 1.36-20.84], P = 0.02). There was no association of MASP-2 levels or MASP2 polymorphisms with autoantibodies, Sjögren's syndrome, nodules and functional class.
In this study, we found the first evidence that MASP-2 deficiency might play an important role in the development of RA and articular symptoms among relatives of RA patients.
[Show abstract][Hide abstract] ABSTRACT: To investigate the association of leprosy with hepatitis B virus (HBV) infection, as yet unknown for South Brazil, we assessed hepatitis B virus coinfection in 199 South Brazilian leprosy patients (119 lepromatous, 15 tuberculoid, 30 borderline, 12 undetermined and 23 unspecified) and in 681 matched blood donors by screening for the hepatitis B virus markers HBSAg and anti-HBc, using ELISA. Positive samples were retested and anti-HBc+ only samples were tested for the hepatitis B surface antibody (anti-HBs). There was a strong association between leprosy and hepatitis B virus infection (OR=9.8, 95% CI=6.4-14.7; p=0.004·E(-30)), as well as an association between HBV infection and lepromatous leprosy, compared to other forms (OR=2.4, 95% CI=1.2-4.8; p=0.017). We also found that confinement due to leprosy was associated with hepatitis B virus infection (OR=3.9, 95% CI=2.1-7.4; p=0.015·E(-3)). Leprosy patients are susceptible to develop hepatitis B virus infection, especially lepromatous. Institutionalized patients, who probably present a stronger Th2 response, have higher risk of being exposed to hepatitis B virus. This clearly emphasizes the need for special care to leprosy patients in preventing hepatitis B virus coinfection in South Brazil.
Preview · Article · Aug 2013 · The Brazilian journal of infectious diseases: an official publication of the Brazilian Society of Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: The gene MASP2 (mannan-binding lectin (MBL)-associated serine protease 2) encodes two proteins, MASP-2 and MAp19 (MBL-associated protein of 19 kDa), bound in plasma to MBL and ficolins. The binding of MBL/MASP-2 and ficolin/MASP-2 complexes to microorganisms activates the lectin pathway of complement and may increase the ingestion of intracellular pathogens such as Mycobacterium leprae.
We haplotyped 11 MASP2 polymorphisms with multiplex sequence-specific PCR in 219 Brazilian leprosy patients (131 lepromatous, 29 borderline, 21 tuberculoid, 14 undetermined, 24 unspecified), 405 healthy Brazilians and 291 Danish blood donors with previously determined MASP-2 and MAp19 levels. We also evaluated MASP-2 levels in further 46 leprosy patients and 69 Brazilian controls.
Two polymorphisms flanking exon 5 of MASP2 were associated with a dominant effect on high MASP-2 levels and an additive effect on low MAp19 levels. Patients presented lower MASP-2 levels (P = 0.0012) than controls. The frequency of the p.126L variant, associated with low MASP-2 levels (below 200 ng/mL), was higher in the patients (P = 0.0002, OR = 4.92), as was the frequency of genotypes with p.126L (P = 0.00006, OR = 5.96). The *1C2-l [AG] haplotype, which harbors p.126L and the deficiency-causing p.439H variant, has a dominant effect on the susceptibility to the disease (P = 0.007, OR = 4.15). Genotypes composed of the *2B1-i and/or *2B2A-i haplotypes, both associated with intermediate MASP-2 levels (200-600 ng/mL), were found to be protective against the disease (P = 0.0014, OR = 0.6). Low MASP-2 levels (P = 0.022), as well as corresponding genotypes with *1C2-l and/or *2A2-l but without *1B1-h or *1B2-h, were more frequent in the lepromatous than in other patients (P = 0.008, OR = 8.8).
In contrast with MBL, low MASP-2 levels increase the susceptibility to leprosy in general and to lepromatous leprosy in particular. MASP2 genotypes and MASP-2 levels might thus be of prognostic value for leprosy progression.
[Show abstract][Hide abstract] ABSTRACT: L-ficolin (encoded by FCN2) binds to acetylated sugar moieties of many pathogens, including Trypanosoma cruzi, promoting their phagocytosis and lysis by the complement system.
We investigated L-ficolin levels in 160 T. cruzi infected patients with chronic Chagas disease and 71 healthy individuals, and FCN2 polymorphisms (-986 G>A, -602 G>A, and -4 A>G in the promoter and A258S in exon 8) in 243 patients, being 88 indeterminate (asymptomatic), 96 with cardiac, 23 with digestive and 33 with cardiodigestive manifestations (two were unspecified) and 305 controls (135 for A258S).
Patients presented lower L-ficolin plasma levels than controls (p<0.0001). Among the different groups of cardiac commitment, individuals with moderate forms had higher L-ficolin levels than the severe forms (P = 0.039). Lower L-ficolin levels were found associated with the 258S variant in the patients (P = 0.034). We found less -4A/G heterozygotes in the cardiac patients, than in the controls (OR = 0.56 [95% CI = 0.33-0.94], P = 0.034). Heterozygote -4A/G genotypes with the 258S variant and 258SS homozygotes were nevertheless more frequent among cardiodigestive patients than in controls (OR = 14.1 [95% CI = 3.5-56.8], P = 0.0001) and in indeterminate patients (OR = 3.2 [95% CI = 1.1-9.4], P = 0.037). We also found an association of the allelic frequency of the 258S variant with cardiodigestive Chagas disease compared to controls (OR = 2.24 [95% CI = 1.1-4.5], P = 0.037). Thus, decreased patient levels of L-ficolin reflect not only protein consumption due to the disease process, but also the higher frequency of the 258S variant in patients with cardiodigestive symptoms.
The very first study on Brazilian cohort associates both L-ficolin plasma levels and FCN2 variants to Chagas disease and subsequent disease progression. The prognostic value of L-ficolin levels and the FCN2*A258S polymorphism should be further evaluated in other settings.