Association of HLA-DRB1 Alleles with Rheumatic Fever and Rheumatic Heart Disease: A Meta-analysis.

BACKGROUND: Rheumatic fever (RF) and its sequel rheumatic heart disease (RHD) is an autoimmune disease caused by an abnormal host immune response to group A streptococcus (GAS) infection. The HLA class II molecules are entailed in immune-mediated infectious, inflammatory, and autoimmune diseases including RHD. However, HLA class II genes are reported to be associated with RF/RHD across different populations with a very little consistency. OBJECTIVE: The aim of the study is to investigate the association between HLA class II genes and RF/RHD by meta-analysis. METHODS: A comprehensive literature search was conducted to identify all relevant case-control studies published before December 31, 2019. The data were extracted using standardized form and pooled odds ratio (OR) with 95% confidence interval (CI) are calculated to assess the strength of the association between HLA class II genes and RF/RHD. RESULTS: Thirteen studies for HLA-DRB1 alleles (1065 patients and 1691 controls) and eight studies for HLA-DQB1 alleles (644 patients and 1088 controls) were finally included. The meta-analysis showed a significantly higher frequency of HLA-DRB1*07 allele (OR = 1.68, P < .0001) in RF/RHD patients when compared to controls, while the frequency of HLA-DRB1*15 allele (OR = 0.60, P = .03) was significantly lower in RF/RHD patients than in controls. However, there were no significant differences in the frequency of HLA-DQB1 alleles between RF/RHD patients and controls. CONCLUSIONS: The results of the meta-analysis suggest that the differential presentation of autoimmune peptides by HLA-DRB1*07 (susceptible) and HLA-DRB1*15 (protective) alleles with different affinities may play a crucial role in the pathogenesis of RF/RHD.

KP-10/Gpr54 attenuates rheumatic arthritis through inactivating NF-κB and MAPK signaling in macrophages.

Rheumatoid arthritis (RA) is an autoimmune disease mainly characterized as chronic inflammation of joint. Both genetic and environmental factors play important roles in RA progression. G protein-coupled receptor 54 (GPR54) and Kisspeptins (KPs), the natural GRP54 ligands encoded by Kiss-1 gene are known to play important roles in immune regulation but the precise role of KP-10/GPR54 in RA remains elusive. Kiss1/Gpr54 expression was determined by immunohistochemistry on protein and real-time PCR on RNA from isolated RA-patient synovial tissue and PBMC. Collagen-induced arthritis (CIA) mouse models were used to investigate the effect of KP-10/Gpr54 on the rheumatic arthritis severity in the mice. The signaling pathway involved in KP-10/GPR54 was assessed by western blot and immunofluorescence.In the present study, we demonstrated that GPR54 upregulation in bone marrow-derived macrophages (BMDM) was associated with the severity of RA. In addition, Gpr54-/- increased the inflammatory cytokines induced by lipopolysaccharide (LPS) in BMDM and diseased severity of CIA (n = 10), while KP-10 reduced the LPS-induced inflammatory cytokines in vitro and ameliorated the CIA symptoms in vivo. Furthermore, we demonstrated that KP-10/GPR54 binds to PP2A-C to suppressed LPS induced NF-κB and MAPK signaling in BMDM. All these findings suggest that KP-10/GPR54 may be a novel therapeutic target for the diagnosis and treatment of RA.

Genetic variants in rheumatic fever and rheumatic heart disease.

Genetic association studies in rheumatic heart disease (RHD) have the potential to contribute toward our understanding of the pathogenetic mechanism, and may shed light on controversies about RHD etiology. Furthermore, genetic association studies may uncover biomarkers that can be used to identify susceptible individuals, and contribute toward developing vaccine and novel therapeutic targets. Genetic predisposition to rheumatic fever and RHD has been hypothesized by findings from familial studies and observed associations between genes located in the human leukocyte antigens on chromosome 6p21.3 and elsewhere in the genome. We sought to summarize, from published Genetic association studies in RHD, evidence on genetic variants implicated in RHD susceptibility. Using HuGENet™ systematic review methods, we evaluated 66 studies reporting on 42 genes. Existing meta-analyses of candidate gene studies suggest that TGF-ß1 [rs1800469], and IL-1ß [rs2853550] single nucleotide polymorphisms (SNPs) contribute to susceptibility to RHD, whereas the TNF-α [rs1800629 and rs361525], TGF-ß1 [rs1800470 and rs4803457], IL-6 [rs1800795], IL-10 [rs1800896] were not associated with RHD. However, candidate gene studies in RF/RHD are relatively small, thus lacking statistical power to identify reliable and reproducible findings, emphasizing the need for large-scale multicenter studies with different populations.

BOB.1 controls memory B-cell fate in the germinal center reaction.

During T cell-dependent (TD) germinal center (GC) responses, naïve B cells are instructed to differentiate towards GC B cells (GCBC), high-affinity long-lived plasma cells (LLPC) or memory B cells (Bmem). Alterations in the B cell-fate choice could contribute to immune dysregulation leading to the loss of self-tolerance and the initiation of autoimmune disease. Here we show that mRNA levels of the transcription regulator BOB.1 are increased in the lymph node compartment of patients with rheumatoid arthritis (RA), a prototypical autoimmune disease caused by the loss of immunological tolerance. Investigating to what extent levels of BOB.1 impact B cells during TD immune responses we found that BOB.1 has a crucial role in determining the B cell-fate decision. High BOB.1 levels promote the generation of cells with phenotypic and functional characteristics of Bmem. Mechanistically, overexpression of BOB.1 drives ABF1 and suppresses BCL6, favouring Bmem over LLPC or recycling GCBC. Low levels of BOB.1 are sufficient for LLPC but not for Bmem differentiation. Our findings demonstrate a novel role for BOB.1 in B cells during TD GC responses and suggest that its dysregulation may contribute to the pathogenesis of RA by disturbing the B cell-fate determination.

Association of rheumatic fever & rheumatic heart disease with plausible early & late-stage disease markers.

BACKGROUND & OBJECTIVES: Rheumatic fever (RF) and rheumatic heart disease (RHD) are the autoimmune sequelae caused by Group A Streptococcus. RHD still remains a major concern in the developing countries due to its poor diagnosis, lack of vaccines and social awareness among population. This study was aimed to identify the plausible early- and late-stage disease markers associated with RF/RHD. METHODS: A total of 84 patients with confirmed pharyngitis (n=18), RF (n=23) and RHD (n=43) were included in the comparative analysis of different factors involved in host-pathogen interaction during RF/RHD pathogenesis. RESULTS: This study revealed high titre of serum antistreptolysin O (ASO) antibody in pharyngitis compared to RF and RHD patients, whereas procollagen type 1 C-peptide (PICP) level was elevated in RHD which showed an inverse correlation with serum ASO titre. The significant elevation of serum anti-peptide associated with RF (PARF) antibody in RF patients was correlated as a probable stage-specific determinant. In addition, pro-inflammatory cytokine profile revealed high levels of interleukin-12 (IL-12)/IL-23p40, IL-17A in RF, whereas IL-6 concentration was higher in RHD compared to healthy controls. INTERPRETATION & CONCLUSIONS: The overall assessment of the factors/ disease markers involved in host-pathogen interaction in RF/RHD may be suggestive of plausible disease marker in different groups of patients. Further studies with larger sample need to be done to better understand RF/RHD pathogenesis.

Clustering of autoimmune diseases in patients with rosacea.

BACKGROUND: Rosacea is a common inflammatory skin condition that shares genetic risk loci with autoimmune diseases such as type 1 diabetes mellitus (T1DM) and celiac disease. A recent genomewide association study identified 90 genetic regions associated with T1DM, celiac disease, multiple sclerosis, and/or rheumatoid arthritis, respectively. However, a possible association with rosacea was not investigated. OBJECTIVE: We evaluated the association between rosacea and T1DM, celiac disease, multiple sclerosis, and rheumatoid arthritis, respectively. METHODS: We performed a population-based case-control study. A total of 6759 patients with rosacea were identified and matched with 33,795 control subjects on age, sex, and calendar time. We used conditional logistic regression to calculate crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: After adjustment for smoking and socioeconomic status, patients with rosacea had significantly increased ORs for T1DM (OR 2.59, 95% CI 1.41-4.73), celiac disease (OR 2.03, 95% CI 1.35-3.07), multiple sclerosis (OR 1.65, 95% CI 1.20-2.28), and rheumatoid arthritis (OR 2.14, 95% CI 1.82-2.52). The association was mainly observed in women. LIMITATIONS: We were unable to distinguish between the different subtypes and severities of rosacea. CONCLUSIONS: Rosacea is associated with T1DM, celiac disease, multiple sclerosis, and rheumatoid arthritis, respectively, in women, whereas the association in men only reached statistical significance for rheumatoid arthritis.

Snippets From the Past: Imaginative Designs--Separating Hereditary From Environmental Effects in pre-DNA Times.

In an attempt to reproduce the results of an inconclusive 1927 report by the British Medical Research Council on the hereditary versus social origins of rheumatic fever, Read, Ciocco, and Taussig, from Johns Hopkins University, with the support of Frost, conducted a case-control study in 1935 and 1936. Their study, which appeared in the American Journal of Hygiene in 1938, was outstanding for its clear and tidy rationale for separating hereditary from environmental causes. The authors compared the prevalence of rheumatic fever among the relatives of 33 children admitted for "incident" rheumatic fever and 33 control children admitted in a tuberculosis clinic for reasons other than rheumatic fever. Both rheumatic fever (cases) and tuberculosis (controls) were diseases of the poor. All family members of both cases and controls, including uncles, aunts, and grandparents, were eligible for interview and physical examination. The results were compatible with the presence of an "inherited predisposition" to rheumatic fever because the disease was more prevalent among the uncles, aunts, and grandparents of case patients than among those of control patients. Methodologically, the paper by Read, Ciocco, and Taussig is an important but almost completely forgotten milestone in the evolution of case-control studies and of genetic epidemiology.

Susceptibility to acute rheumatic fever based on differential expression of genes involved in cytotoxicity, chemotaxis, and apoptosis.

It is unknown why only some individuals are susceptible to acute rheumatic fever (ARF). We investigated whether there are differences in the immune response, detectable by gene expression, between individuals who are susceptible to ARF and those who are not. Peripheral blood mononuclear cells (PBMCs) from 15 ARF-susceptible and 10 nonsusceptible (control) adults were stimulated with rheumatogenic (Rh+) group A streptococci (GAS) or nonrheumatogenic (Rh-) GAS. RNA from stimulated PBMCs from each subject was cohybridized with RNA from unstimulated PBMCs on oligonucleotide arrays to compare gene expression. Thirty-four genes were significantly differentially expressed between ARF-susceptible and control groups after stimulation with Rh+ GAS. A total of 982 genes were differentially expressed between Rh+ GAS- and Rh- GAS-stimulated samples from ARF-susceptible individuals. Thirteen genes were differentially expressed in the same direction (predominantly decreased) between the two study groups and between the two stimulation conditions, giving a strong indication of their involvement. Seven of these were immune response genes involved in cytotoxicity, chemotaxis, and apoptosis. There was variability in the degree of expression change between individuals. The high proportion of differentially expressed apoptotic and immune response genes supports the current model of autoimmune and cytokine dysregulation in ARF. This study also raises the possibility that a "failed" immune response, involving decreased expression of cytotoxic and apoptotic genes, contributes to the immunopathogenesis of ARF.

Association of macrophage migration inhibitory factor and mannose-binding lectin-2 gene polymorphisms in acute rheumatic fever.

BACKGROUND: Macrophage migration inhibitory factor and mannose-binding lectin-2 play important roles in the pathogenesis of several acute and chronic inflammatory/autoimmune disorders. The aim of the study was to investigate any possible association between migration inhibitory factor and mannose-binding lectin-2 gene polymorphisms and acute rheumatic fever in children. Material and methods A total of 38 unrelated children with acute rheumatic fever and 40 age- and sex-matched healthy controls were analysed for codon 54 A/B polymorphism in mannose-binding lectin-2 gene and -173 G/C polymorphism in migration inhibitory factor gene by using the polymerase chain reaction method. RESULTS: Frequency of BB genotype of mannose-binding lectin-2 gene was higher in the patient group. Interestingly, children with acute rheumatic fever with AA genotype tended to have chorea compared with children with BB genotype. There was a statistically significant increase in frequency of the migration inhibitory factor -173 CC genotype in patients compared with the control subjects. CONCLUSION: The present study is the first to investigate the mannose-binding lectin-2 gene polymorphism in children with acute rheumatic fever. BB genotype of mannose-binding lectin-2 (codon 54) and CC genotype of migration inhibitory factor (-173) may have a role in the immunoinflammatory process of acute rheumatic fever.

[Immunogenetic aspects of early rheumatoid arthritis].

The study is aimed to investigate the distribution of alleles of HLA-DRB1 gene in patients with early rheumatoid arthritis and healthy individuals in Russian population, and evaluate their significance as molecular genetic markers of rheumatoid arthritis predisposition and protection. The association between alleles of HLA-DRB1 genes, antibodies to cyclic citrullinated peptides and IgM rheumatoid factor was also studied. Low and high resolution HLA-DRB1 genotyping were compared. In the cohort of patients with early rheumatoid arthritis, the alleles of HLA-DRB1 gene were found to be markers of rheumatoid arthritis protection/risk, especially in the homozygous state. They determined production of antibodies to cyclic citrullinated peptides but were not associated with rheumatoid factor IgM levels. These findings support different autoimmune mechanisms of rheumatoid arthritis pathogenesis.

Genetic Evidence Supporting Causal Roles of mTOR-Dependent Proteins in Rheumatic Fever: A Two-Sample Randomized Mendelian Study.

BACKGROUND: The expression of signaling molecules downstream of the mammalian target of rapamycin (mTOR) is dysregulated in patients with rheumatic fever (RF), but the causality of mTOR on RF remains unknown. This study aimed to investigate the causal effects of the mTOR-dependent proteins in RF. METHODS: The summary data for targets of the mTOR signaling were acquired from the publicly available INTERVAL study GWAS data. Data on RF have been obtained from the Integrated Epidemiology Unit GWAS database (38,209 cases and 156,711 healthy controls). A two-sample Mendelian randomization (MR) study was conducted to examine the association of RF risk and mTOR-dependent proteins (EIF4EBP2, EIF-4E, EIF-4G, EIF-4A, RP-S6K, and ATG7), including the inverse-variance weighted (IVW) method, MR-Egger, and weighted median, which was followed by sensitivity analyses. RESULTS: RP-S6K is associated with a lowered risk of RF with an odds ratio (OR) of 0.97, 95% confidence interval (95% CI) of 0.94-0.99 (p = 0.027). In contrast, ATG7 accounts for higher risk of RF with an OR of 1.05 (95% CI = 1.00-1.12, p = 0.047). No apparent heterogeneity and no horizontal pleiotropy were observed in the sensitivity analysis (p > 0.05). No statistical significance was identified for levels of EIF4A, EIF4G, EIF4E-BP2, and RP-S6K with RF risk (p > 0.05). CONCLUSION: MR found robust evidence of a causal association between RF and mTOR. RP-S6K and ATG7 may be targeted for intervention by repurposing existing therapeutics to reduce the risk of RF.

Profiling system-wide variations and similarities between Rheumatic Heart Disease and Acute Rheumatic Fever-A pilot analysis.

Rheumatic heart disease (RHD) continues to affect developing countries with low income due to the lack of resources and effective diagnostic techniques. Understanding the genetic basis common to both the diseases and that of progression from its prequel disease state, Acute Rheumatic Fever (ARF), would aid in developing predictive biomarkers and improving patient care. To gain system-wide molecular insights into possible causes for progression, in this pilot study, we collected blood transcriptomes from ARF (5) and RHD (5) patients. Using an integrated transcriptome and network analysis approach, we identified a subnetwork comprising the most significantly differentially expressed genes and most perturbed pathways in RHD compared to ARF. For example, the chemokine signaling pathway was seen to be upregulated, while tryptophan metabolism was found to be downregulated in RHD. The subnetworks of variation between the two conditions provide unbiased molecular-level insights into the host processes that may be linked with the progression of ARF to RHD, which has the potential to inform future diagnostics and therapeutic strategies. We also found a significantly raised neutrophil/lymphocyte ratio in both ARF and RHD cohorts. Activated neutrophils and inhibited Natural Killer cell gene signatures reflected the drivers of the inflammatory process typical to both disease conditions.

Resveratrol-mediated SIRT-1 interactions with p300 modulate receptor activator of NF-kappaB ligand (RANKL) activation of NF-kappaB signaling and inhibit osteoclastogenesis in bone-derived cells.

Resveratrol is a polyphenolic phytoestrogen that has been shown to exhibit potent anti-oxidant, anti-inflammatory, and anti-catabolic properties. Increased osteoclastic and decreased osteoblastic activities result in bone resorption and loss of bone mass. These changes have been implicated in pathological processes in rheumatoid arthritis and osteoporosis. Receptor activator of NF-κB ligand (RANKL), a member of the TNF superfamily, is a major mediator of bone loss. In this study, we investigated the effects of resveratrol on RANKL during bone morphogenesis in high density bone cultures in vitro. Untreated bone-derived cell cultures produced well organized bone-like structures with a bone-specific matrix. Treatment with RANKL induced formation of tartrate-resistant acid phosphatase-positive multinucleated cells that exhibited morphological features of osteoclasts. RANKL induced NF-κB activation, whereas pretreatment with resveratrol completely inhibited this activation and suppressed the activation of IκBα kinase and IκBα phosphorylation and degradation. RANKL up-regulated p300 (a histone acetyltransferase) expression, which, in turn, promoted acetylation of NF-κB. Resveratrol inhibited RANKL-induced acetylation and nuclear translocation of NF-κB in a time- and concentration-dependent manner. In addition, activation of Sirt-1 (a histone deacetylase) by resveratrol induced Sirt-1-p300 association in bone-derived and preosteoblastic cells, leading to deacetylation of RANKL-induced NF-κB, inhibition of NF-κB transcriptional activation, and osteoclastogenesis. Co-treatment with resveratrol activated the bone transcription factors Cbfa-1 and Sirt-1 and induced the formation of Sirt-1-Cbfa-1 complexes. Overall, these results demonstrate that resveratrol-activated Sirt-1 plays pivotal roles in regulating the balance between the osteoclastic versus osteoblastic activity result in bone formation in vitro thereby highlighting its therapeutic potential for treating osteoporosis and rheumatoid arthritis-related bone loss.

Role of cytokine gene (IFN-γ, TNF-α, TGF-ß1, IL-6, and IL-10) polymorphisms in pathogenesis of acute rheumatic fever in Turkish children.

UNLABELLED: Acute rheumatic fever (ARF) is a delayed immunologically mediated sequela of throat infection by group A ß-hemolytic streptococci. Inflammatory cytokines may play a pathogenic role in ARF. The objective of this study was to investigate the potential associations between interferon (IFN)-γ, interleukin (IL)-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-ß1, and IL-10 gene polymorphisms and childhood ARF. Thirty-eight ARF patients and 40 age- and sex-matched healthy controls were analyzed for eight polymorphisms in five different cytokine genes [IFN-γ (+874), IL-6 (-174), TNF-α (-308), TGF-ß1 (+10, +25), and IL-10 (-1082, -819, -592)]. Cytokine genotyping was performed by polymerase chain reaction sequence-specific primer methods. Patients with ARF had significantly higher frequencies of IFN-γ (+874) polymorphism in both TT genotype (p=0.0002) and T allele (p=0.0004). No statistically significant differences were observed in genotypes, haplotypes, and allele frequencies of IL-6, TNF-α, TGF-ß1, and IL-10 genes between ARF and control groups (p>0.05). GG genotype frequency of TNF-α gene (low expression) was higher in patients who had previous ARF history (p=0.006). High expression of TGF-ß1 (TT/GG, TC/GG) was more frequent in patients with CRP positivity (p=0.034). IL-6 CC genotype (low expression) frequency was higher in patients with tricuspid valve insufficiency (p=0.002), while IFN-γ TT genotype (high expression) frequency was higher in patients with mitral valve prolapse (p=0.049). CONCLUSION: High expression of the IFN-γ gene may carry a higher risk for ARF in Turkish children, while IL-6, TNF-α, and TGF-ß1 may have an impact in mediating some clinical and laboratory manifestations of the disease.

Understanding rheumatic fever.

Through a comprehensive review of the recent findings on rheumatic fever, we intend to propose a new physiopathologic model for this disease. A Medline search was performed for all articles containing the terms rheumatic fever or rheumatic heart disease in title or abstract from 1970 to 2011. Best evidence qualitative technique was used to select the most relevant. The scientific interest on rheumatic fever has notably diminished throughout the twentieth century as evidenced by the comparison of the proportion of articles in which RF was a subject in 1950 (0.26%) and today (0.03%) [Pubmed]. However, RF remains a major medical and social problem in the developing world and in the so-called hotspots, where it still causes around 500.000 deaths each year, not too different from the pre-antibiotic era. The role of genetic factors in RF susceptibility is discussed. Familiar aggregation, similarity of disease patterns between siblings, identical twin, and HLA correlation studies are evidence for a genetic influence on RF susceptibility. The suspect-involved genes fall mainly into those capable of immunologic mediation. Molecular mimicry explains the triggering of RF, but an intense and sustained inflammation is needed to cause sequels. Also, RF patients vary greatly in terms of symptoms. It is likely that a genetic background directing immune response towards a predominantly Th1 or Th2 pattern contributes to these features. The recent findings on rheumatic fever provide important insight on its physiopathology that helps understanding this prototype post-infectious autoimmune disease giving insights on other autoimmune conditions.

Some of the people, some of the time: susceptibility to acute rheumatic fever.

Acute rheumatic fever is a major cause of heart disease in large parts of the world, but it remains unknown why only a small fraction of those who are infected with rheumatogenic group A streptococci develop an abnormal immune response that leads to acute rheumatic fever. An understanding of the mechanisms underlying host susceptibility can provide important insights into pathogenesis that in turn can inform new treatments. Extensive searches for susceptibility factors have been undertaken, including human leukocyte antigens, B-cell alloantigens, and cytokine genes. Although significant associations have been found between genetic factors and acute rheumatic fever, study results often conflict with each other. This review explores current understanding about host susceptibility to acute rheumatic fever and provides an overall perspective to the number of studies that have recently addressed this subject.

The primary prevention of rheumatic fever.

Rheumatic fever (RF), caused by untreated group A streptococcal (GAS) pharyngitis, is a major cause of morbidity and mortality throughout much of the less developed world and disadvantaged populations (Indigenous and other) in the developed world. Through systematic literature searches, our group has identified potential risk factors for RF and possible interventions for its prevention. The causes can be divided into biological factors, socio-economic, and lifestyle factors and health-care systems and services. Currently, the most promising medical areas look to be improving access to health care and introducing community and school-based sore throat interventions (which aim to diagnose and treat GAS pharyngitis). We could find no convincing support for skin sepsis causing RF. Overall evidence suggests that measures that aim to alleviate poverty and crowding may also reduce the incidence of RF. In comparatively rich countries such as New Zealand and Australia, urgent measures based on available evidence should be undertaken to reduce the very striking health disparity seen with RF and its sequela, rheumatic heart disease in our at-risk populations.

Genetics of rheumatic fever and rheumatic heart disease.

Rheumatic heart disease (RHD) is a complication of group A streptococcal infection that results from a complex interaction between the genetic make-up of the host, the infection itself and several other environmental factors, largely reflecting poverty. RHD is estimated to affect 33.4 million people and results in 10.5 million disability-adjusted life-years lost globally. The disease has long been considered heritable but still little is known about the host genetic factors that increase or reduce the risk of developing RHD. In the 1980s and 1990s, several reports linked the disease to the human leukocyte antigen (HLA) locus on chromosome 6, followed in the 2000s by reports implicating additional candidate regions elsewhere in the genome. Subsequently, the search for susceptibility loci has been reinvigorated by the use of genome-wide association studies (GWAS) through which millions of variants can be tested for association in thousands of individuals. Early findings implicate not only HLA, particularly the HLA-DQA1 to HLA-DQB1 region, but also the immunoglobulin heavy chain locus, including the IGHV4-61 gene segment, on chromosome 14. In this Review, we assess the emerging role of GWAS in assessing RHD, outlining both the advantages and disadvantages of this approach. We also highlight the potential use of large-scale, publicly available data and the value of international collaboration to facilitate comprehensive studies that produce findings that have implications for clinical practice.

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.