Mannose Binding Lectin and C3 Serum Levels in Coronary Artery Disease: A Cross-Sectional Study

BACKGROUND

The process of tissue injury in coronary artery disease (CAD) has been associated with activation of the complement system, partly due to the action of mannose-binding lectin (MBL) and C3, which are expressed in atherosclerotic lesions.

OBJECTIVE

The aim of this study was to evaluate the serum levels of MBL and C3 in patients with CAD and to compare them with healthy controls. Additionally, we aim to assess the correlation between MBL and C3 levels and cardiometabolic parameters.

METHODS

MBL and C3 serum concentration were determined by ELISA and immunoturbidimetry, respectively, in up to 119 patients undergoing coronary angiography for CAD evaluation, comprising 48 individuals diagnosed with acute myocardial infarction (MI) and 71 without MI. A total of 93 paired healthy controls were included in the study.

RESULTS

Individuals with CAD had MBL serum concentration higher than controls (p = .002), regardless of the presence of MI (p = .006). In addition, high concentration of MBL (>2000 ng/mL) was more frequent in patients with CAD (p = .007; OR = 2.6; 95% CI = 1.3-5.1). C3 levels were not significantly associated with any of the patient groups but were positively correlated with cardiometabolic parameters such as body mass index (BMI) and triglycerides levels.

CONCLUSIONS

Higher concentrations of MBL were found to be associated with CAD, whereas C3 levels were found to be associated with cardiovascular risk factors.

Ficolin-3 in chronic Chagas disease: Low serum levels associated with the risk of cardiac insufficiency

AIMS

To investigate whether FCN3 polymorphisms and circulating ficolin-3 levels were associated with clinical forms of chronic Chagas disease (CD) and to assess their potential use as biomarkers for the disease or its severity.

METHODS AND RESULTS

FCN3 polymorphisms (g.1637delC (rs532781899) in exon 5; g.3524_3532insTATTTGGCC (rs28362807) in intron 5 and g.4473C > A) (rs4494157) in intron 7) were determined in 178 chronic CD patients (65 asymptomatic, 68 cardiac, 21 digestive and 24 cardiodigestive), and 285 healthy controls by sequence-specific PCR. Ficolin-3 serum levels, measured by ELISA in 80 patients and 80 controls, did not differ between groups. On the other hand, ficolin-3 levels were positively correlated with left ventricular ejection fraction (P = .002; r = .5), with lower levels associated with increased risk of cardiac insufficiency (P = .033; OR 7.21, 95%IC 1.17-44.4). Ficolin-3 levels were positively correlated with ficolin-2 (P = .021; r = .63), and negatively with MBL (P = .002; r = -.36) and pentraxin-3 (P = .04; r = -.32) levels. No significant results were observed for the investigated FCN3 polymorphisms and CD. The g.1637del/1637C heterozygotes presented lower ficolin-3 levels than g.1637C/1637C homozygotes in the control group (P = .023).

CONCLUSION

Low ficolin-3 levels may play a role in the pathophysiology of cardiac insufficiency associated with CD.

Case Report: High Mannose-Binding Lectin Serum Determined by MBL2 Genotype and Risk for Clinical Progression to Chagasic Cardiomyopathy: A Case Report of Three Patients

Chagas disease (CD), caused by infection with the parasite Trypanosoma cruzi, leads to severe cardiomyopathy in 20-30% of patients, whereas the remainder may stay asymptomatic and never develop cardiomyopathy or other clinical manifestations. The underlying cause for this variable outcome is not fully characterized, although previous studies have found high levels of circulating mannose-binding lectin (MBL) to be associated with cardiac failure echocardiographic changes. We report three indeterminate (asymptomatic) chronic Chagas patients who were followed up for 10 years. Two of these patients developed chronic chagasic cardiomyopathy (CCC) during this follow-up period and, when genotyped, were found to be carriers of the high MBL producer HYPA/HYPA genotype, suggesting that genetically determined high MBL serum might be associated with the risk of CCC development. These results suggest the use of MBL quantification and MBL2 genotyping as tools for clinical assessment in patients with chronic CD.

Chagas Disease: From Discovery to a Worldwide Health Problem

Carlos Chagas discovered American trypanosomiasis, also named Chagas disease (CD) in his honor, just over a century ago. He described the clinical aspects of the disease, characterized by its etiological agent (Trypanosoma cruzi) and identified its insect vector. Initially, CD occurred only in Latin America and was considered a silent and poorly visible disease. More recently, CD became a neglected worldwide disease with a high morbimortality rate and substantial social impact, emerging as a significant public health threat. In this context, it is crucial to better understand better the epidemiological scenarios of CD and its transmission dynamics, involving people infected and at risk of infection, diversity of the parasite, vector species, and T. cruzi reservoirs. Although efforts have been made by endemic and non-endemic countries to control, treat, and interrupt disease transmission, the cure or complete eradication of CD are still topics of great concern and require global attention. Considering the current scenario of CD, also affecting non-endemic places such as Canada, USA, Europe, Australia, and Japan, in this review we aim to describe the spread of CD cases worldwide since its discovery until it has become a global public health concern.

Human collectin-11 (COLEC11) and its synergic genetic interaction with MASP2 are associated with the pathophysiology of Chagas Disease

Chagas Disease (CD) is an anthropozoonosis caused by Trypanosoma cruzi. With complex pathophysiology and variable clinical presentation, CD outcome can be influenced by parasite persistence and the host immune response. Complement activation is one of the primary defense mechanisms against pathogens, which can be initiated via pathogen recognition by pattern recognition molecules (PRMs). Collectin-11 is a multifunctional soluble PRM lectin, widely distributed throughout the body, with important participation in host defense, homeostasis, and embryogenesis. In complex with mannose-binding lectin-associated serine proteases (MASPs), collectin-11 may initiate the activation of complement, playing a role against pathogens, including T. cruzi. In this study, collectin-11 plasma levels and COLEC11 variants in exon 7 were assessed in a Brazilian cohort of 251 patients with chronic CD and 108 healthy controls. Gene-gene interactions between COLEC11 and MASP2 variants were analyzed. Collectin-11 levels were significantly decreased in CD patients compared to controls (p<0.0001). The allele rs7567833G, the genotypes rs7567833AG and rs7567833GG, and the COLEC11*GGC haplotype were related to T. cruzi infection and clinical progression towards symptomatic CD. COLEC11 and MASP2*CD risk genotypes were associated with cardiomyopathy (p = 0.014; OR 9.3, 95% CI 1.2–74) and with the cardiodigestive form of CD (p = 0.005; OR 15.2, 95% CI 1.7–137), suggesting that both loci act synergistically in immune modulation of the disease. The decreased levels of collectin-11 in CD patients may be associated with the disease process. The COLEC11 variant rs7567833G and also the COLEC11 and MASP2*CD risk genotype interaction were associated with the pathophysiology of CD.

The heterogeneity of clinical progression during chronic Trypanosoma cruzi infection and the mechanisms determining why some individuals develop symptoms whereas others remain asymptomatic are still poorly understood. The pathogenesis of chronic Chagas Disease (CD) has been attributed mainly to the persistence of the causing parasite and the character of individual host immune responses. Collectin-11 is a host immune response molecule with affinity for sugars found on the T. cruzi’s surface. Together with mannose-binding lectin-associated serine proteases (MASPs), it triggers the host defense response against pathogens. Genetic variants and protein levels of MASP-2 and the mannose-binding lectin (MBL), a molecule structurally similar to collectin-11, have been found to be associated with susceptibility to T. cruzi infection and clinical progression to cardiomyopathy. This prompted us to investigate collectin-11 genetic variants and protein levels in 251 patients with chronic CD and 108 healthy individuals, and to examine the effect of gene interaction between COLEC11 and MASP2 risk mutations. We found an association to CD infection with COLEC11 gene variants and reduced collectin-11 levels. The concomitant presence of these genetic variants and MASP2 risk mutations greatly increased the odds for cardiomyopathy. This is the first study to reveal a role for collectin-11 and COLEC11-MASP2 gene interaction in the pathogenesis of CD.

Cardiovascular risk and mannose binding lectin in patients with rheumatoid arthritis from southern Brazil

BACKGROUND

Mannose binding lectin (MBL) appears to be involved in susceptibility to rheumatoid arthritis (RA), in the inflammatory process and in the genesis of atherosclerotic disease.

OBJECTIVE

To study the association of MBL serum levels and its genotypic variation with carotid arteries intimal thickness (IMT) in RA patients from Southern Brazil.

METHODS

MBL serum levels, MBL2 genotyping and IMT were investigated in 90 RA patients along with their demographic, clinical and laboratory profile. MBL levels and MBL2 genotyping were evaluated in 90 healthy controls.

RESULTS

A significant lower MBL serum concentration was observed in patients with RA in relation to controls (528 ng/mL vs 937.5 ng/mL, p = 0.05, respectively). The median IMT in RA patients was 0.59 mm (0.51 to 0.85 mm). There was no correlation between levels of MBL with disease activity, erythrocyte sedimentation rate, autoantibodies presence or IMT (p = NS). A weak and negative correlation was found between MBL and CRP levels (Rho = -0.24; p = 0.02;). The MBL2 variant at codon 54 (variant B) and HYPA haplotype were the most frequently observed in the RA sample (67.5% and 31.7%). MBL2 wild type (A/A) were associated with lower IMT when compared with heterozygotes (A/O; p = 0.04) and low producers (O/O; p = 0.05). In addition, high producers genotypes had lower levels of CRP when compared with medium (p = 0.04) or with low producers (p = 0.05).

CONCLUSION

RA patients had lower MBL levels than controls. MBL were negatively associated with CRP serum levels; low MBL genotypes producers increased thickness of the IMT than high producers.

Effects of MASP2 haplotypes and MASP-2 levels in hepatitis C-infected patients

Mannan-binding lectin (MBL) and MBL-associated serine protease 2 (MASP-2) are components of the lectin pathway, which activate the complement system after binding to the HCV structural proteins E1 and E2. We haplotyped 11 MASP2 polymorphisms in 103 HCV patients and 205 controls and measured MASP-2 levels in 67 HCV patients and 77 controls to better understand the role of MASP-2 in hepatitis C susceptibility and disease severity according to viral genotype and fibrosis levels. The haplotype block MASP2*ARDP was associated with protection against HCV infection (OR = 0.49, p = .044) and lower MASP-2 levels in controls (p = .021), while haplotype block AGTDVRC was significantly increased in patients (OR = 7.58, p = .003). MASP-2 levels were lower in patients than in controls (p < .001) and in patients with viral genotype 1 or 4 (poor responders to treatment) than genotype 3 (p = .022) and correlated inversely with the levels of alkaline phosphatase, especially in individuals with fibrosis 3 or 4 (R = -.7, p = .005). MASP2 gene polymorphisms modulate basal gene expression, which may influence the quality of complement response against HCV. MASP-2 levels decrease during chronic disease, independently of MASP2 genotypes, most probably due to consumption and attenuation mechanisms of viral origin and by the reduced liver function, the site of MASP-2 production.

Serine Proteases in the Lectin Pathway of the Complement System

The complement system plays a crucial role in host defense against pathogen infections and in the recognition and removal of damaged or altered self-components. Complement system activation can be initiated by three different pathways—classical, alternative, and lectin pathways—resulting in a proteolytic cascade, which culminates in multiple biological processes including opsonization and phagocytosis of intruders, inflammation, cell lysis, and removal of immune complexes and apoptotic cells. Furthermore, it also functions as a link between the innate and adaptive immune responses. The lectin pathway (LP) activation is mediated by serine proteases, termed mannan-binding lectin (MBL)-associated serine proteases (MASPs), which are associated with the pattern recognition molecules (PRMs) that recognize carbohydrates or acetylated compounds on surfaces of pathogens or apoptotic cells. These result in the proteolysis of complement C2 and C4 generating C3 convertase (C4b2a), which carries forward the activation cascade of complements, culminating in the elimination of foreign molecules. This chapter presents an overview of the complement system focusing on the characterization of MASPs and its genes, as well as its functions in the immune response.

Genetically Determined MBL Deficiency Is Associated with Protection against Chronic Cardiomyopathy in Chagas Disease

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.

Chagas disease is considered an important neglected tropical disease, affecting approximately ten million people in Latin America. Although most infected individuals remain asymptomatic, one third of patients develop a chronic heart disease, with progressive inflammation, increase of myocardium, arrhythmia, cardiac insufficiency and heart failure. To date, there is no available marker to indicate the progression neither to determinate the severity of heart damage. Mannan binding lectin (MBL) is an important protein of the immune system able to recognize specific regions on the microorganism surfaces (including Trypanosoma cruzi, the causal agent of Chagas disease) which activate the complement system, a crucial mechanism of the effector immunity. MBL levels and protein activity are affected by genetic differences, named polymorphisms, in the MBL2 gene. This is the first Brazilian study with MBL2 polymorphisms in chronic Chagas disease. We sequenced two regions of MBL2 gene in 196 patients and 202 controls. We found that a polymorphism associated with deficient complement activation protects against Chagas disease and patients with deficiency-associated genotypes presented less echocardiographic alterations. 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 lead us to suggest that genetically determined MBL deficiency plays a protective role against the development and progression of chronic Chagas disease.

Association of complement factor B allotypes and serum biomarkers in rheumatoid arthritis patients and their relatives

The aim of the study was to investigate the allotypic variability of complement factor B (BF) in patients and relatives with rheumatoid arthritis (RA) and its association with serological biomarkers and clinical features of the disease. BF allotypes were determined by high-voltage agarose gel electrophoresis in serum samples of 180 patients with RA, 198 relatives and 98 controls from Southern Brazil. Anticyclic citrullinated peptide (anti-CCP), antimutated citrullinated vimentin (anti-MCV) and IgA-rheumatoid factor (RF) were determined by ELISA and IgM-RF by latex agglutination in all samples. No significant differences were found in the allotypic variants of BF between patients with RA, relatives and controls, nor associations with gender and age of RA onset. BF*S07 allotype was significantly associated with extra-articular manifestations (EAMs; Secondary Sjögren Syndrome, pneumonitis, rheumatoid nodules) in patients with RA (P = 0.02; OR = 6.62). Patients with phenotype BF F had lower positivity for anti-MCV biomarker (P = 0.02; OR = 0.22) and those with allotype BF*S had higher prevalence of this autoantibody (P = 0.02; OR = 3.77). An increased frequency of RF-IgA was detected in relatives of patients with RA with BF FS07 phenotype (P = 0.02; OR = 7.78). Complement BF variability did not influence the development of RA in the studied patients, but BF variants may act as markers of disease prognosis, such as development of EAMs, corroborating with the role of the alternative pathway in the pathogenesis of RA.

Mannose binding lectin deposition in skin of lupus erythematosus patients: a case series

INTRODUCTION

Mannose binding lectin (MBL) has been linked to predisposition to systemic lupus erythematosus (SLE) and to disease activity. Some studies found deposits of MBL in glomerular tissue of patients with lupus nephritis. There is no research about the deposition of MBL in skin.

MATERIALS AND METHODS

Skin biopsies from lesional and non lesional skin of 4 discoid lupus erythematosus (DLE) and 10 SLE patients were submitted to immunofluorescence staining for IgG, IgA, IgM, C3, C4, C1q, C5b-9 and MBL. Charts were reviewed for demographic, clinical and serological data. Patients with SLE had disease activity measured by SLEDAI.

RESULTS

MBL was found only in SLE lesional skin and its presence showed an association trend towards higher disease activity. Deposition of C5b-9 occurred in vessels only in patients with SLE (70%) and in the two patients with kidney involvement.

CONCLUSIONS

MBL deposition was found in the lesional skin of SLE patients but not in SLE non lesional skin nor in DLE patients, and it seems to be less frequent and less strong than observed in the kidneys biopsies, suggesting that the complement participation in the pathophysiology of SLE process may not be the same in these two clinical manifestations.

Association of MASP-2 levels and MASP2 gene polymorphisms with rheumatoid arthritis in patients and their relatives

Background

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).

Methods

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.

Results

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.

Conclusions

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.

Phylogenetic nomenclature and evolution of mannose-binding lectin (MBL2) haplotypes

Background

Polymorphisms of the mannose-binding lectin gene (MBL2) affect the concentration and functional efficiency of the protein. We recently used haplotype-specific sequencing to identify 23 MBL2 haplotypes, associated with enhanced susceptibility to several diseases.

Results

In this work, we applied the same method in 288 and 470 chromosomes from Gabonese and European adults, respectively, and found three new haplotypes in the last group. We propose a phylogenetic nomenclature to standardize MBL2 studies and found two major phylogenetic branches due to six strongly linked polymorphisms associated with high MBL production. They presented high Fst values and were imbedded in regions with high nucleotide diversity and significant Tajima's D values. Compared to others using small sample sizes and unphased genotypic data, we found differences in haplotyping, frequency estimation, Fu and Li's D* and Fst results.

Conclusion

Using extensive testing for selective neutrality, we confirmed that stochastic evolutionary factors have had a major role in shaping this polymorphic gene worldwide.

Ficolin 2 (FCN2) functional polymorphisms and the risk of rheumatic fever and rheumatic heart disease

Ficolins are pattern-recognition proteins involved in innate immunity, which upon binding to their specific pathogen-associated molecular patterns on the microbial surfaces trigger the immune response either by binding to collectin cellular receptors or by initiating the complement lectin pathway. In humans, three ficolin genes have been identified, which encode ficolin-1 (M-ficolin), ficolin-2 (L-ficolin) and ficolin-3 (H-ficolin or Hakata antigen). Ficolin-2 was shown to bind to lipoteichoic acid, a cell wall constituent in all Gram-positive bacteria such as Streptococcus pyogenes, which is the aetiological agent of rheumatic fever (RF) and its most severe sequelae, chronic rheumatic heart disease (CRHD). Here we investigated polymorphisms in the promoter region of the FCN2 gene (at positions -986/-602 and +4) in 122 patients with RF and CRHD and in 210 healthy subjects from the same geographic region and socioeconomic background. The haplotype -986/-602/-4 G/G/A, which is related to low levels of L-ficolin, was observed more frequently in the CRHD group when compared to the healthy subjects [99/162, 61.1% versus 211/420, 50.2%, odds ratio (OR) 1.6, confidence interval (CI) 95% 1.1-2.3, P = 0.021]. The haplotype -986/-602/-4 A/G/A was observed more frequently in the healthy group when compared to the affected (RF plus CRHD) subjects (31/420, 7.4% versus 6/244, 2.5%, OR 3.2, CI 95% 0.13-0.77, P = 0.008). Based on those findings, one can conclude that polymorphisms associated with low levels of L-ficolin level may predispose an individual to recurrent and/or more severe streptococcal infection.

Haplotype specific-sequencing reveals MBL2 association with asymptomatic Plasmodium falciparum infection

Background

Mannose binding lectin (MBL) has an important role in the activation of the complement system and opsonization of pathogenic microorganisms. Frequent polymorphisms found in the MBL2 gene affect the concentration and functionality of the protein and are associated with enhanced susceptibility to severe malaria in African children. Most MBL2 typing strategies were designed to the analysis of selected variants, the significance of whole haplotypes is poorly known. In this work, a new typing strategy was developed and validated in an association analysis of MBL2 with adult asymptomatic infection.

Methods

MBL2 allele-specific fragments of 144 healthy Gabonese adults were amplified by using haplotype-specific sequencing (HSS), a new strategy that combines sequence-specific PCR and sequence-based typing. The Gabonese were investigated for the presence of Plasmodium falciparum parasitaemia by the amplification of parasite genes, immunochromatographic antigen detection and microscopic analysis. HSS results were also compared with a previously used real-time PCR (RT-PCR) method in 72 Euro-Brazilians.

Results

Fourteen polymorphisms were identified beside the commonly investigated promoter (H, L; X, Y; P, Q) and exon 1 (A, O; O = B, C or D) variants. The MBL2*LYPA/LYPA genotype was associated with the absence of asymptomatic infection (P = 0.017), whereas the MBL2*LYQC haplotype and YA/YO + YO/YO genotypes were associated with positive parasite counts in asymptomatic adults (P = 0.033 and 0.018, respectively). The associations were specific to LYPA (identical to the reference sequence Y16577) and LYQC (Y16578) and would not have been revealed by standard genotyping, as there was no association with LYPA and LYQC haplotypes carrying new polymorphisms defined by sequence-based typing. In contrast, HSS and RT-PCR produced very similar results in the less diverse European-derived population.

Conclusion

In this work, a new typing strategy for a highly polymorphic gene was developed and validated focusing on the asymptomatic status of P. falciparum-infected adults. In populations with high nucleotide diversity, it allowed for the identification of associations with fine-scaled haplotypes that would not have been found using common typing techniques. In this preliminary study, MBL2 haplotypes or SNPs linked to them were found associated with susceptibility to infection and parasitaemia control of asymptomatic adults.

Complement C3 F and BF S allotypes are risk factors for Chagas disease cardiomyopathy

The heterogeneity in the clinical expression of Chagas disease gives strong evidences for the involvement of genetic factors on its pathogenesis. Several studies have indicated different markers of genetic susceptibility to Chagas cardiomyopathy. In the present study, we present evidence of association between complement C3 and BF allotypes, and the susceptibility to Chagas disease and the development of cardiomyopathy. C3, BF, C4A, C4B and C2 polymorphism were determined in 100 seropositive Chagasic patients [cardiomyopathic (CARD), n = 57; asymptomatic indetermined (IND), n = 43] and in 100 non-related seronegative healthy controls. Patients and controls were matched according to their ethnic and geographical origin. A significantly increased frequency of C3F was observed in patients with the CARD form (8/57 14.03%), when compared with those presenting the IND form (0/43, 0%; RR 7.0) and with the healthy controls (5/100, 5%; RR 3.1). A negative association of the BF S allotype was observed in the CARD patients (19/57 33.33%) and in the Chagas total (38/100 38.0%), when compared with the controls (55/100, 55.0%; RR 0.4). All other C3, BF, C4A, C4B and C2 alleles showed no significant differences. These results suggest the allele C3F as a susceptible marker for the progression of the CARD form. On the other hand, BF S may represent a protective role against severe CARD disease. These results corroborate the importance of the alternative pathway in Trypanosoma cruzi infection and indicate possible genetic markers of Chagas cardiomyopathy.

Complement activation in infective endocarditis: correlation with extracardiac manifestations and prognosis

In an infectious process complement activation is necessary for a proper immune and inflammatory response, but when exacerbated may cause tissue injuries. In infective endocarditis (IE) patients tend to develop high titres of circulating immune complexes (CIC) that activate complement. The aim of this study was to evaluate for the first time complement activation in IE for possible correlation with extracardiac manifestations and clinical prognosis. Twenty patients with IE, 14 healthy controls and 15 patients presenting mitral and aortic valve lesions (with no signs of either infection or other associated diseases), were studied. Plasma levels of C3adesArg, SC5b-9, C1rs-C1Inh and C3b(Bb)P were determined by ELISA and C3d by double decker immunoelectrophoresis. C3 and C4 levels were assayed by turbidimetry and CIC by ELISA. Elevation of plasma levels of all complement activation products, with the exception of C3b(Bb)P, indicated a significant classical pathway activation in IE patients when compared to controls (C3d: P < 0.00004; C3adesArg: P < 0.03, SC5b-9: P < 0.01, C1rs-C1Inh: P < 0.00007). CIC levels were significantly increased (P < 0.005) and C3 reduced in IE patients (P < 0.05). Elevated C3d (P < 0.02) and C3adesArg (P < 0.03) levels were associated with pulmonary manifestations. In addition, C3d was significantly elevated in the patients who died when compared to those who had a good recovery (P < 0.02). Our data demonstrate the activation of the complement classical pathway, most probably mediated by CIC, in IE and suggests C3d and C3adesArg as possible markers for extracardiac lesion and severity of the disease.