A genetic variant rs1801274 in FCGR2A as a potential risk marker for Kawasaki disease: a case-control study and meta-analysis

Genetic variations in low-to-medium-affinity Fcγ receptors and autoimmune neutropenia in early childhood in a Danish cohort

Autoimmune neutropenia (AIN) in early childhood is caused by autoantibodies directed against antigens on the neutrophil membrane and is a frequent cause of neutropenia in children. Association of AIN with Fcγ receptor (FCGR) 3B variants is well described. In this study, we investigate genetic variations in the FCGR locus and copy number variation of FCGR3B. A total of 130 antibody-positive AIN patients, 64 with specific anti-HNA-1a antibodies and 66 with broad-reacting anti-FcγRIIIb antibodies, were genotyped with a multiplex ligation probe assay and compared with healthy controls. Positive findings were confirmed with real-time q-PCR. We determined copy numbers of the FCGR2 and FCGR3 genes and the following SNPs: FCGR2A Q62W (rs201218628), FCGR2A H166R (rs1801274), FCGR2B I232T (rs1050501), FCGR3A V176F (rs396991), haplotypes for FCGR2B/C promoters (rs3219018/rs780467580), FCGR2C STOP/ORF and HNA-1 genotypes in FCGR3B (rs447536, rs448740, rs52820103, rs428888 and rs2290834). Generally, associations were antibody specific, with all associations being representative of the anti-HNA-1a-positive group, while the only association found in the anti-FcγRIIIb group was with the HNA-1 genotype. An increased risk of AIN was observed for patients with one copy of FCGR3B; the HNA genotypes HNA-1a, HNA-1aa or HNA-1aac; the FCGR2A 166H and FCGR2B 232I variations; and no copies of FCGR2B 2B.4. A decreased risk was observed for HNA genotype HNA-1bb; FCGR2A 166R; FCGR2B 232T; and one copy of FCGR2B promoter 2B.4. We conclude that in our Danish cohort, there was a strong association between variation in the FCGR locus and AIN. The findings of different genetic associations between autoantibody groups could indicate the presence of two different disease entities and disease heterogeneity.

Association of the host genetic factors, hypercholesterolemia and diabetes with mild influenza in an Iranian population

BACKGROUND

Variation in host genetic factors may result in variation in the host immune response to the infection. Some chronic diseases may also affect individuals' susceptibility to infectious diseases. The aim of this study was to evaluate the association of the host genetic factors mostly involved in inflammation, as well as hypercholesterolemia and diabetes with mild flu in an Iranian population.

METHODS

In this cross-sectional study, nasopharyngeal swab samples were collected from 93 patients referred to primary care centers of Markazi, Semnan, and Zanjan provinces (central Iran) due to flu-like symptoms between March 2015 and December 2018. Of these, PCR test identified 49 influenza A/H1N1 and 44 flu-negative individuals. Twelve single-nucleotide polymorphisms (SNPs) in RPAIN, FCGR2A, MBL-2, CD55, C1QBP, IL-10, TNF-α and an unknown gene were genotyped using iPLEX GOLD SNP genotyping analysis. Hypercholesterolemia and diabetes status was determined based on the physician diagnosis. Association of the host genetic variants, hypercholesterolemia and diabetes with mild A/H1N1 flu was assessed with univariable and multivariable logistic regression analysis as implemented in Stata software (v.14). Statistical tests were considered as significant at 0.05 levels.

RESULTS

Frequency of diabetes and hypercholesterolemia, as well as participants mean age was significantly higher in the flu-negative rather than the flu-positive group. Of 12 SNPs, nine did not show any significant association with mild flu in our study (rs1801274, rs1800451, rs2564978, rs361525, rs1800450, rs1800871, rs1800872, rs1800896, rs1800629). Possessing G vs. A allele in two SNPs (rs3786054 and rs8070740) was associated with a threefold increase in the chance of mild flu when compared to flu-negative patients (95% CI: 1.1, 22.0). Possessing C allele (vs. A) in the rs9856661 locus also increased the chance of mild flu up to 2 folds (95% CI: 1.0, 10.0).

CONCLUSION

The results showed that possessing the G allele in either rs3786054 or rs8070740 loci in C1QBP and RPAIN genes, respectively, increased the risk of H1N1 infection up to 3.3 folds, regardless of the patient's age, BMI, diabetes, and hypercholesterolemia. Complementary functional genomic studies would shed more light on the underlying mechanism of human immunity associated with these genetic markers. The identified genetic factors may have the same role in susceptibility to similar respiratory infections with RNA viruses, like SARS, MERS and COVID-19. Future genetic association studies targeting these RNA viruses, especially COVID-19 is recommended. Studies on other ethnic groups would also shed light on possible ethnic variations in genetic susceptibility to respiratory RNA viruses. Trial registry IR.PII.REC.1399.063.

Quercetin as a Natural Therapeutic Candidate for the Treatment of Influenza Virus

The medical burden caused by respiratory manifestations of influenza virus (IV) outbreak as an infectious respiratory disease is so great that governments in both developed and developing countries have allocated significant national budget toward the development of strategies for prevention, control, and treatment of this infection, which is seemingly common and treatable, but can be deadly. Frequent mutations in its genome structure often result in resistance to standard medications. Thus, new generations of treatments are critical to combat this ever-evolving infection. Plant materials and active compounds have been tested for many years, including, more recently, active compounds like flavonoids. Quercetin is a compound belonging to the flavonols class and has shown therapeutic effects against influenza virus. The focus of this review includes viral pathogenesis as well as the application of quercetin and its derivatives as a complementary therapy in controlling influenza and its related symptoms based on the targets. We also touch on the potential of this class of compounds for treatment of SARS-COV-2, the cause of new pandemic.

Lower CMV and EBV Exposure in Children With Kawasaki Disease Suggests an Under-Challenged Immune System

Background: Kawasaki Disease (KD) is a pediatric vasculitis of which the pathogenesis is unclear. The hypothesis is that genetically pre-disposed children develop KD when they encounter a pathogen which remains most often unidentified or pathogen derived factors. Since age is a dominant factor, prior immune status in children could influence their reactivity and hence the acquisition of KD. We hypothesized that systemic immune responses early in life could protect against developing KD. With this study we tested whether the incidence of previous systemic cytomegalovirus (CMV) or Epstein-Barr virus (EBV) infection is lower in children with KD compared to healthy age-matched controls. Methods and Results: We compared 86 KD patients with an age-matched control group regarding CMV and EBV VCA IgG measurements (taken before or 9 months after IVIG treatment). We found that both CMV and EBV had an almost 2-fold lower seroprevalence in the KD population than in the control group. Conclusions: We suggest that an under-challenged immune system causes an altered immune reactivity which may affect the response to a pathological trigger causing KD in susceptible children.

Current State of Precision Medicine in Primary Systemic Vasculitides

Precision medicine (PM) is an emerging data-driven health care approach that integrates phenotypic, genomic, epigenetic, and environmental factors unique to an individual. The goal of PM is to facilitate diagnosis, predict effective therapy, and avoid adverse reactions specific for each patient. The forefront of PM is in oncology; nonetheless, it is developing in other fields of medicine, including rheumatology. Recent studies on elucidating the genetic architecture of polygenic and monogenic rheumatological diseases have made PM possible by enabling physicians to customize medical treatment through the incorporation of clinical features and genetic data. For complex inflammatory disorders, the prevailing paradigm is that disease susceptibility is due to additive effects of common reduced-penetrance gene variants and environmental factors. Efforts have been made to calculate cumulative genetic risk score (GRS) and to relate specific susceptibility alleles for use of target therapies. The discovery of rare patients with single-gene high-penetrance mutations informed our understanding of pathways driving systemic inflammation. Here, we review the advances in practicing PM in patients with primary systemic vasculitides (PSVs). We summarize recent genetic studies and discuss current knowledge on the contribution of epigenetic factors and extracellular vesicles (EVs) in disease progression and treatment response. Implementation of PM in PSVs is a developing field that will require analysis of a large cohort of patients to validate data from genomics, transcriptomics, metabolomics, proteomics, and epigenomics studies for accurate disease profiling. This multi-omics approach to study disease pathogeneses should ultimately provide a powerful tool for stratification of patients to receive tailored optimal therapies and for monitoring their disease activity.

Genetic Variation in Low-To-Medium-Affinity Fcγ Receptors: Functional Consequences, Disease Associations, and Opportunities for Personalized Medicine

Fc-gamma receptors (FcγR) are the cellular receptors for Immunoglobulin G (IgG). Upon binding of complexed IgG, FcγRs can trigger various cellular immune effector functions, thereby linking the adaptive and innate immune systems. In humans, six classic FcγRs are known: one high-affinity receptor (FcγRI) and five low-to-medium-affinity FcγRs (FcγRIIA, -B and -C, FcγRIIIA and -B). In this review we describe the five genes encoding the low-to-medium -affinity FcγRs (FCGR2A, FCGR2B, FCGR2C, FCGR3A, and FCGR3B), including well-characterized functionally relevant single nucleotide polymorphisms (SNPs), haplotypes as well as copy number variants (CNVs), which occur in distinct copy number regions across the locus. The evolution of the locus is also discussed. Importantly, we recommend a consistent nomenclature of genetic variants in the FCGR2/3 locus. Next, we focus on the relevance of genetic variation in the FCGR2/3 locus in auto-immune and auto-inflammatory diseases, highlighting pathophysiological insights that are informed by genetic association studies. Finally, we illustrate how specific FcγR variants relate to variation in treatment responses and prognosis amongst autoimmune diseases, cancer and transplant immunology, suggesting novel opportunities for personalized medicine.

Extensive Ethnic Variation and Linkage Disequilibrium at the FCGR2/3 Locus: Different Genetic Associations Revealed in Kawasaki Disease

The human Fc-gamma receptors (FcγRs) link adaptive and innate immunity by binding immunoglobulin G (IgG). All human low-affinity FcγRs are encoded by the FCGR2/3 locus containing functional single nucleotide polymorphisms (SNPs) and gene copy number variants. This locus is notoriously difficult to genotype and high-throughput methods commonly used focus on only a few SNPs. We performed multiplex ligation-dependent probe amplification for all relevant genetic variations at the FCGR2/3 locus in >4,000 individuals to define linkage disequilibrium (LD) and allele frequencies in different populations. Strong LD and extensive ethnic variation in allele frequencies was found across the locus. LD was strongest for the FCGR2C-ORF haplotype (rs759550223+rs76277413), which leads to expression of FcγRIIc. In Europeans, the FCGR2C-ORF haplotype showed strong LD with, among others, rs201218628 (FCGR2A-Q27W, r² = 0.63). LD between these two variants was weaker (r² = 0.17) in Africans, whereas the FCGR2C-ORF haplotype was nearly absent in Asians (minor allele frequency <0.005%). The FCGR2C-ORF haplotype and rs1801274 (FCGR2A-H131R) were in weak LD (r² = 0.08) in Europeans. We evaluated the importance of ethnic variation and LD in Kawasaki Disease (KD), an acute vasculitis in children with increased incidence in Asians. An association of rs1801274 with KD was previously shown in ethnically diverse genome-wide association studies. Now, we show in 1,028 European KD patients that the FCGR2C-ORF haplotype, although nearly absent in Asians, was more strongly associated with susceptibility to KD than rs1801274 in Europeans. Our data illustrate the importance of interpreting findings of association studies concerning the FCGR2/3 locus with knowledge of LD and ethnic variation.

Association of miR-146a Gene Polymorphism at loci rs2910164 G/C, rs57095329 A/G, and rs6864584 T/C with Susceptibility to Kawasaki Disease in Chinese Children

OBJECTIVE

To investigate the genetic association of miR-146a gene polymorphisms at loci rs2910164 G/C, rs57095329 A/G, and rs6864584 T/C in patients with Kawasaki disease (KD) and coronary artery lesions (CAL).

METHODS

There were 120 patients with KD and 126 healthy subjects in this study. The genotype of loci rs2910164 G/C, rs57095329 A/G, and rs6864584 T/C of miR-146a gene were detected by polymerase chain reaction-sequence-based typing.

RESULTS

For miR-146a gene polymorphisms at loci rs2910164 G/C, rs57095329 A/G, and rs6864584 T/C, there were no significant difference of genotype frequencies and allele frequencies between KD group and healthy control group, or between the IVIG-resistant group and IVIG-sensitive group (P > 0.05). In KD with coronary artery lesions (KD-CAL) group, the genotype frequencies of GG were higher than that in KD without coronary artery lesion (KD-WO) group at locus rs2910164 G/C polymorphisms of miR-146a gene (χ² = 6.660, P = 0.036), patients with KD carried genotype of GG were at 3.636 times higher risk of getting coronary artery lesions than those of non-carriers (χ² = 6.455, P = 0.018, OR = 3.636, 95%CI = 1.280-10.262). While there was no significant difference of allele frequency of G and C between KD-CAL group and KD-WO group (P > 0.05). In KD-CAL group, the allele frequency of A was higher than that in KD-WO group at locus rs57095329 A/G polymorphisms of miR-146a gene (χ² = 4.745, P = 0.035), carriers with allele A were at 2.422 times higher risk of getting coronary artery lesions than those of non-carriers (χ² = 4.745, P = 0.035, OR = 2.422, 95%CI = 1.073-5.465), while there was no significant difference of genotype frequency of AA, AG, and GG types between KD-CAL group and KD-WO group (P > 0.05). There was no significant difference of genotype frequencies of TT, TC, and CC types and allele frequencies of T and C types between KD-CAL group and KD-WO group at locus rs6864584 T/C polymorphisms of miR-146a gene (P > 0.05).

CONCLUSIONS

The significant association has been found between the genotype and allele frequency of the miR-146a gene loci rs2910164 G/C and rs57095329 A/G, the genotype GG of rs2910164 G/C, and allele A of rs57095329 A/G were risk factors for getting coronary artery lesions.

Biomarkers for Kawasaki Disease: Clinical Utility and the Challenges Ahead

Kawasaki disease (KD) has replaced acute rheumatic fever as the most common cause of acquired heart disease in children in the developed world and is increasingly being recognized from several developing countries. It is a systemic vasculitis with a predilection for coronary arteries. The diagnosis is based on a constellation of clinical findings that appear in a temporal sequence. Quite understandably, this can become a problem in situations wherein the clinical features are not typical. In such situations, it can be very difficult, if not impossible, to arrive at a diagnosis. Several biomarkers have been recognized in children with acute KD but none of these has reasonably high sensitivity and specificity in predicting the course of the illness. A line up of inflammatory, proteomic, gene expression and micro-RNA based biomarkers has been studied in association with KD. The commonly used inflammatory markers e.g. erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and total leucocyte counts (TLC) lack specificity for KD. Proteomic studies are based on the identification of specific proteins in serum, plasma and urine by gel electrophoresis. A host of genetic studies have identified genes associated with KD and some of these genes can predict the course and coronary outcomes in the affected individuals. Most of these tests are in the early stages of their development and some of these can predict the course, propensity to develop coronary artery sequelae, intravenous immunoglobulin (IVIg) resistance and the severity of the illness in a patient. Development of clinical criteria based on these tests will improve our diagnostic acumen and aid in early identification and prevention of cardiovascular complications.

The Rare Anaphylaxis-Associated FcγRIIa3 Exhibits Distinct Characteristics From the Canonical FcγRIIa1

FcγRIIa is an activating FcγR, unique to humans and non-human primates. It induces antibody-dependent proinflammatory responses and exists predominantly as FcγRIIa1. A unique splice variant, we designated FcγRIIa3, has been reported to be associated with anaphylactic reactions to intravenous immunoglobulins (IVIg) therapy. We aim to define the functional consequences of this FcγRIIa variant associated with adverse responses to IVIg therapy and evaluate the frequency of associated SNPs. FcγRIIa forms from macaque and human PBMCs were investigated for IgG-subclass specificity, biochemistry, membrane localization, and functional activity. Disease-associated SNPs were analyzed by sequencing genomic DNA from 224 individuals with immunodeficiency or autoimmune disease. FcγRIIa3 was identified in macaque and human PBMC. The FcγRIIa3 is distinguished from the canonical FcγRIIa1 by a unique 19-amino acid cytoplasmic insertion and these two FcγRIIa forms responded distinctly to antibody ligation. Whereas FcγRIIa1 was rapidly internalized, FcγRIIa3 was retained longer at the membrane, inducing greater calcium mobilization and cell degranulation. Four FCGR2A SNPs were identified including the previously reported intronic SNP associated with anaphylaxis, but in only 1 of 224 individuals. The unique cytoplasmic element of FcγRIIa3 delays internalization and is associated with enhanced cellular activation. The frequency of the immunodeficiency-associated SNP varies between disease populations but interestingly occurred at a lower frequency than previously reported. None-the-less enhanced FcγRIIa3 function may promote a proinflammatory environment and predispose to pathological inflammatory responses.

The rs1625579 T>G polymorphism in the miRNA-13 gene confers a risk of early- onset Kawasaki disease in a southern Chinese population

Background

Kawasaki disease (KD) mainly manifests as excessive inflammation and vascular endothelial cell injury. This disease generally occurs in children younger than 5 years of age and is more severe in children younger than 12 months. KD affects males and females at a ratio of 1.5:1. Polymorphisms of the rs1625579 locus in the miR-13 gene are associated with schizophrenia susceptibility, and high glucose-induced upregulation of miR-137 in vascular endothelial cells promotes monocyte chemotaxis and inflammatory cytokine secretion in gestational diabetes mellitus. However, researchers have not reported whether rs1625579 is associated with KD susceptibility or onset. Therefore, we investigated the relationship between the miRNA-13 rs1625579 T>G polymorphism and KD susceptibility.

Methods

TaqMan real-time polymerase chain reaction was applied to determine the genotypes of 532 patients with KD (365 males and 167 females) and 623 control subjects (402 males and 221 females).

Results

Comparison of all cases with all controls revealed that the rs1625579 T>G polymorphism was not associated with KD susceptibility. However, a subgroup analysis revealed that subjects with the rs1625579 TG/GG genotypes exhibited a significantly higher onset risk for KD before 12 months of age than carriers of the TT genotype (adjusted age and gender odds ratio=1.99, 95% CI=1.04-3.83; P=0.039).

Conclusion

Our results indicate that the rs1625579 T>G polymorphism confers a risk of early-onset KD in southern Chinese children.

An update on the role of epigenetics in systemic vasculitis

PURPOSE OF REVIEW

The purpose of this review is to discuss recent observations of epigenetic changes related to the complex pathogenesis of systemic vasculitides and their contribution to the field.

RECENT FINDINGS

There have been new observations of epigenetic changes in vasculitis and their potential role in disease pathogenesis in antineutrophil cytoplasmic antibody-associated vasculitis, giant-cell arteritis, Kawasaki disease, Behçet's disease, and IgA vasculitis. Some of this recent work has focused on the efficacy of using DNA methylation and miRNA expression as clinical biomarkers for disease activity and how DNA methylation and histone modifications interact to regulate disease-related gene expression.

SUMMARY

DNA methylation, histone modification, and miRNA expression changes are all fruitful ground for biomarker discovery and therapeutic targets in vasculitis. Current knowledge has provided targeted and suggested effects, but in many cases, has relied upon small cohorts, cosmopolitan cell populations, and limited knowledge of functional interactions. Expanding our knowledge of how these epigenetic mechanisms interact in a disease-specific and cell-specific manner will help to better understand the pathogenesis of systemic vasculitis.

Association of FCGR2A rs1801274 polymorphism with susceptibility to autoimmune diseases: A meta-analysis

OBJECTIVES

The aim of this meta-analysis was to estimate the association between the FCGR2A rs1801274 polymorphism and the susceptibility to autoimmune diseases more precisely.

METHODS

A meta-analysis was conducted on the association between the FCGR2A gene variants and ADs by allelic contrast, homozygote contrast, the recessive model, and the dominant model.

RESULTS

A total of 17 studies with 30 comparisons in different populations and genotype-methods were available for this meta-analysis, including 10 Kawasaki disease (KD), 7 Ulcerative colitis (UC), 6 Crohn's disease (CD), 3 Rheumatoid arthritis (RA), 2 Systemic lupus erythematosus (SLE), 1 Autoimmune thyroid disease (ATD) and 1 diabetes mellitus type 1 (T1D). A significant association between FCGR2A rs1801274 polymorphism were found in KD (OR = 1.409, P < 0.001) and UC (OR = 1.237, P < 0.001). A overall meta-analysis increased risk of AD significant association between FCGR2A rs1801274 gene polymorphism and ADs under allelic (OR = 1.378, P=0.000), homozygous (OR: 1.866, P=0.001), dominant (OR = 1.667, P = 0.000) and recessive (OR = 1.434, P=0.000) in Asian population. Meanwhile, a decreased risk of AD was detected in the allelic (OR= 0.882, P = 0.011), homozygous (OR = 0.777, P = 0.013), dominant (OR = 0.850, P = 0.032) and recessive (OR = 0.840, P = 0.048) in African-American population.

CONCLUSIONS

This meta-analysis demonstrates that the FCGR2A rs1801274 G-allele confers susceptibility to KD and UC. Data also suggests that the FCGR2A rs1801274 polymorphism may be associated with the susceptibility of multiple ADs in Asian and African-American populations.

Angiotensin-converting enzyme insertion/deletion polymorphism and susceptibility to Kawasaki disease: a meta-analysis

BACKGROUND

The angiotensin-converting enzyme (ACE) I/D polymorphism has been reported to be associated with Kawasaki disease (KD), but studies to date present conflicting results.

OBJECTIVES

The aim of this study is to derive a more precise estimation of the association between the ACE I/D polymorphism and KD risk.

METHODS

PubMed, EMBASE, CNKI and Wangfang databases were retrievaled to identify for relevant studies from inception to May 2017. Pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using Stata 12.0 software.

RESULTS

A total of 6 case-control studies comprising 634 patients and 458 controls were included in the meta-analysis, and we found a significant association between the ACE I/D polymorphism and KD risk (D vs I:OR = 0.81, 95%CI = 0.31-2.11;DD vs II: OR = 1.03, 95%CI = 0.42-2.54; DI vs II: OR = 1.44, 95%CI = 1.09-1.90; dominant model: OR = 1.43, 95%CI = 1.11-1.85; recessive model: OR = 1.21, 95%CI = 0.44-3.29 ). When stratified by sample size>200, this polymorphism is associated with an increased the risk of KD.

CONCLUSION

The I/D polymorphism in the ACE gene may be associated with susceptibility to KD.

Male-specific association of the FCGR2A His167Arg polymorphism with Kawasaki disease

Kawasaki disease (KD) is an acute systemic vasculitis that can potentially cause coronary artery aneurysms in some children. KD occurs approximately 1.5 times more frequently in males than in females. To identify sex-specific genetic variants that are involved in KD pathogenesis in children, we performed a sex-stratified genome-wide association study (GWAS), using the Illumina HumanOmni1-Quad BeadChip data (249 cases and 1,000 controls) and a replication study for the 34 sex-specific candidate SNPs in an independent sample set (671 cases and 3,553 controls). Male-specific associations were detected in three common variants: rs1801274 in FCGR2A [odds ratio (OR) = 1.40, P = 9.31 × 10-5], rs12516652 in SEMA6A (OR = 1.87, P = 3.12 × 10-4), and rs5771303 near IL17REL (OR = 1.57, P = 2.53 × 10-5). The male-specific association of FCGR2A, but not SEMA6A and IL17REL, was also replicated in a Japanese population (OR = 1.74, P = 1.04 × 10-4 in males vs. OR = 1.22, P = 0.191 in females). In a meta-analysis with 1,461 cases and 5,302 controls, a very strong association of KD with the nonsynonymous SNP rs1801274 (p.His167Arg, previously assigned as p.His131Arg) in FCGR2A was confirmed in males (OR = 1.48, P = 1.43 × 10-7), but not in the females (OR = 1.17, P = 0.055). The present study demonstrates that p.His167Arg, a KD-associated FCGR2A variant, acts as a susceptibility gene in males only. Overall, the gender differences associated with FCGR2A in KD provide a new insight into KD susceptibility.

Dissecting Kawasaki disease: a state-of-the-art review

Kawasaki disease (KD) is a pediatric vasculitis with coronary artery aneurysms (CAA) as its main complication. The diagnosis is based on the presence of persistent fever and clinical features including exanthema, lymphadenopathy, conjunctival injection, and changes to the mucosae and extremities. Although the etiology remains unknown, the current consensus is that it is likely caused by an (infectious) trigger initiating an abnormal immune response in genetically predisposed children. Treatment consists of high dose intravenous immunoglobulin (IVIG) and is directed at preventing the development of CAA. Unfortunately, 10-20% of all patients fail to respond to IVIG and these children need additional anti-inflammatory treatment. Coronary artery lesions are diagnosed by echocardiography in the acute and subacute phases. Both absolute arterial diameters and z-scores, adjusted for height and weight, are used as criteria for CAA. Close monitoring of CAA is important as ischemic symptoms or myocardial infarction due to thrombosis or stenosis can occur. These complications are most likely to arise in the largest, so-called giant CAA. Apart from the presence of CAA, it is unclear whether KD causes an increased cardiovascular risk due to the vasculitis itself.

CONCLUSION

Many aspects of KD remain unknown, although there is growing knowledge on the etiology, treatment, and development and classification of CAA. Since children with previous KD are entering adulthood, long-term follow-up is increasingly important. What is known: • Kawasaki disease (KD) is a pediatric vasculitis with coronary artery damage as its main complication. • Although KD approaches its 50th birthday since its first description, many aspects of the disease remain poorly understood. What is new: • In recent years, multiple genetic candidate pathways involved in KD have been identified, with recently promising information about the ITPKC pathway. • As increasing numbers of KD patients are reaching adulthood, increasing information is available about the long-term consequences of coronary artery damage and broader cardiovascular risk.

Pro-inflammatory cytokine single nucleotide polymorphisms in Kawasaki disease

AIM

Kawasaki disease (KD) is a systemic vasculitis of children associated with cardiovascular sequelae. Proinflammatory cytokines play a major role in KD pathogenesis. However, their role is both influenced and modified by regulatory T-cells. IL-1 gene cluster, IL-6 and TNF-α polymorphisms have shown significant associations with some vasculitides. Herein we investigated their role in KD.

METHODS

Fifty-five patients with KD who were randomly selected from referrals to the main pediatric hospital were enrolled in this case-control study. Single nucleotide polymorphisms (SNPs) of the following genes were assessed in patients and 140 healthy subjects as control group: IL-1α at -889 (rs1800587), IL-1β at -511 (rs16944), IL-1β at +3962 (rs1143634), IL-1R at Pst-I 1970 (rs2234650), IL-1RN/A at Mspa-I 11100 (rs315952), TNF-α at -308 (rs1800629), TNF-α at -238, IL-6 at -174 (rs1800795) and IL-6 at +565.

RESULTS

Twenty-one percent of the control group had A allele at TNF-α -238 while only 8% of KD patients had A allele at this position (P = 0.003, OR [95%CI] = 0.32 [0.14-0.71]). Consistently, TNF-α genotype GG at -238 had significant association with KD (OR [95% CI] = 4.31 [1.79-10.73]). Most controls carried the CG genotype at IL-6 -174 (n = 93 [66.9%]) while GG genotype was the most common genotype (n = 27 [49%]) among patients. Carriers of the GG haplotype at TNF-α (-308, -238) were significantly more prevalent among the KD group. No association was found between IL-1 gene cluster, allelic or haplotypic variants and KD.

CONCLUSION

TNF-α GG genotype at -238 and GG haplotype at positions -308 and -238 were associated with KD in an Iranian population.

The His131Arg substitution in the FCGR2A gene (rs1801274) is not associated with the severity of influenza A(H1N1)pdm09 infection

BACKGROUND

The virulence and pathogenicity of different influenza strains are responsible for a more or less severe disease. Recent studies have attempted to understand how host genetic factors may influence the clinical presentation of the disease. In the present study, the His131Arg (rs1801274) polymorphism was investigated in individuals from a Brazilian admixed population with a diagnosis of influenza A(H1N1)pdm09 infection.

METHODS

In the present study, the influence of the His131Arg (rs1801274) polymorphism, a variant of the FCGR2A gene, was investigated in 436 patients with a diagnosis of influenza A(H1N1)pdm09, evaluated at health services in the northern and northeastern regions of Brazil between June 2009 and August 2010. Patients were divided into a group of non-hospitalized patients (n = 192) and a group of hospitalized patients (n = 244; 100 of them died).

RESULTS

No significant difference in the allele or genotype frequencies of the rs1801274 polymorphism was observed between groups (p = 0.952 and p = 0.388). Multinomial logistic regression showed no effect of the rs1801274 polymorphism on severity or death of patients from the Brazilian admixed population (p = 0.368 and p = 0.469).

CONCLUSIONS

The rs1801274 polymorphism is not associated with severe disease in patients infected with influenza A(H1N1)pdm09.

Genome-Wide Association Study Identifies Novel Susceptibility Genes Associated with Coronary Artery Aneurysm Formation in Kawasaki Disease

Kawasaki disease (KD) or Kawasaki syndrome is known as a vasculitis of small to medium-sized vessels, and coronary arteries are predominantly involved in childhood. Generally, 20–25% of untreated with IVIG and 3–5% of treated KD patients have been developed coronary artery lesions (CALs), such as dilatation and aneurysm. Understanding how coronary artery aneurysms (CAAs) are established and maintained in KD patients is therefore of great importance. Upon our previous genotyping data of 157 valid KD subjects, a genome-wide association study (GWAS) has been conducted among 11 (7%) CAA-developed KD patients to reveal five significant genetic variants passed pre-defined thresholds and resulted in two novel susceptibility protein-coding genes, which are NEBL (rs16921209 (P = 7.44 × 10⁻⁹; OR = 32.22) and rs7922552 (P = 8.43 × 10⁻⁹; OR = 32.0)) and TUBA3C (rs17076896 (P = 8.04 × 10⁻⁹; OR = 21.03)). Their known functions have been reported to associate with cardiac muscle and tubulin, respectively. As a result, this might imply their putative roles of establishing CAAs during KD progression. Additionally, various model analyses have been utilized to determine dominant and recessive inheritance patterns of identified susceptibility mutations. Finally, all susceptibility genes hit by significant genetic variants were further investigated and the top three representative gene-ontology (GO) clusters were regulation of cell projection organization, neuron recognition, and peptidyl-threonine phosphorylation. Our results help to depict the potential routes of the pathogenesis of CAAs in KD patients and will facilitate researchers to improve the diagnosis and prognosis of KD in personalized medicine.

Genetic variants of ADAM17 are implicated in the pathological process of Kawasaki disease and secondary coronary artery lesions via the TGF-β/SMAD3 signaling pathway

Kawasaki disease (KD) is a systemic vasculitis childhood disease frequently complicating coronary artery lesions (CALs). Recently, the gene encoding a disintegrin and metalloprotease 17 (ADAM17) was found to modify vascular pathology in humans by differentially regulating the transforming growth factor-β (TGF-β) signaling pathway, which affects KD/CAL susceptibility. To explore the potential role of ADAM17 in KD occurrence and outcomes, we investigated the association of 28 single nucleotide polymorphisms (SNPs) in ADAM17 and three pathway genes of TGF-β signaling with KD phenotypes in a Han Chinese population, including 392 KD patients and 421 non-KD controls. Three ADAM17 SNPs showed an association with KD risk, which was further confirmed by haplotype analysis. The effect of ADAM17 on KD was also shown by multi-variable logistic regression analysis. In two-locus model analyses with SNPs in ADAM17 and TGF-β signaling pathway genes, stronger compound effects on the risk of KD and secondary CAL formation were observed relative to comparable single SNPs.

CONCLUSION

Our results suggest that ADAM17 contributes to the KD risk and is involved in secondary CAL formation via the TGF-β/SMAD3 signaling pathway. This further enriches our understanding of the importance of the signaling pathway in KD occurrence and outcomes.

WHAT IS KNOWN

• The transforming growth factor (TGF)-β/SMAD3 signaling pathway greatly influences susceptibility to Kawasaki disease (KD) and secondary coronary artery lesions (CALs) and/or the treatment response of intravenous immunoglobulin. • A disintegrin and metalloprotease 17 (ADAM17) effectively reduces TGF-β signaling by cleaving TGF-β receptor type-1, while ADAM17 genetic variants modify human vascular pathology by differentially regulating this signaling although it is unknown whether ADAM17 contributes to KD phenotypes. What is New: • ADAM17 genetic variants were shown to be associated with KD risk, even when excluding the influence of TGF-β signaling pathway genes, suggesting that ADAM17 is an important KD susceptibility-related genetic locus. • The more significant compound effects of two-locus models, combining single nucleotide polymorphisms (SNPs) in ADAM17 and other TGF-β signaling pathway genes including TGFB2 and SMAD3, on KD phenotypes relative to single SNPs suggest that ADAM17 is also involved in secondary CAL formation and confers the risk of KD/CALs via the TGF-β/SMAD3 signaling pathway.

The immunomodulatory effects of intravenous immunoglobulin therapy in Kawasaki disease

The introduction of intravenous immunoglobulin (IVIG) for modulation of inflammation in acute Kawasaki disease was a great therapeutic triumph. However, three decades later, the mechanisms underlying immune regulation by IVIG are only beginning to be revealed. Stimulation of an immature myeloid population of dendritic cells that secretes IL-10 and the elucidation of Fc-specific natural regulatory T cells provide insights into the mechanisms of IVIG. Other potential mechanisms include provision of agent-specific neutralizing antibody, anti-idiotype and anti-cytokine antibodies, blockade of activating Fcγ receptors and stimulation of the inhibitory FcγRIIb receptor. New initiatives must seek to understand the mechanisms of IVIG in order to replace it one day with more affordable and more targeted therapies.

Ethnic Kawasaki Disease Risk Associated with Blood Mercury and Cadmium in U.S. Children

Kawasaki disease (KD) primarily affects children <5 years of age (75%-80%) and is currently the leading cause of acquired heart disease in developed nations. Even when residing in the West, East Asian children are 10 to 20 times more likely to develop KD. We hypothesized cultural variations influencing pediatric mercury (Hg) exposure from seafood consumption may mediate ethnic KD risk among children in the United States. Hospitalization rates of KD in US children aged 0-4 years (n = 10,880) and blood Hg levels in US children aged 1-5 years (n = 713) were determined using separate US federal datasets. Our cohort primarily presented with blood Hg levels <0.1 micrograms (µg) per kg bodyweight (96.5%) that are considered normal and subtoxic. Increased ethnic KD risk was significantly associated with both increasing levels and detection rates of blood Hg or cadmium (Cd) in a linear dose-responsive manner between ethnic African, Asian, Caucasian, and Hispanic children in the US (p ≤ 0.05). Increasing low-dose exposure to Hg or Cd may induce KD or contribute to its later development in susceptible children. However, our preliminary results require further replication in other ethnic populations, in addition to more in-depth examination of metal exposure and toxicokinetics.

Systematic confirmation study of GWAS-identified genetic variants for Kawasaki disease in a Chinese population

Genome-wide association studies (GWASs) have identified multiple single nucleotide polymorphisms (SNPs) associated with Kawasaki disease (KD). In this study, we replicated the associations of 10 GWAS-identified SNPs with KD in a Han Chinese population. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression, and cumulative effect of non-risk genotypes were also performed. Although none of the SNPs reached the corrected significance level, 4 SNPs showed nominal associations with KD risk. Compared with their respective wild type counterparts, rs1801274 AG+GG genotypes and rs3818298 TC+CC genotypes were nominally associated with the reduced risk of KD (OR = 0.77, 95% CI = 0.59-0.99, P = 0.045; OR = 0.74, 95% CI = 0.56-0.98, P = 0.038). Meanwhile, rs1801274 GG genotype, rs2736340 CC genotype or rs4813003 TT genotype showed a reduced risk trend (OR = 0.57, 95% CI = 0.35-0.93, P = 0.024; OR = 0.46, 95% CI = 0.26-0.83, P = 0.010; OR = 0.64, 95% CI = 0.43-0.94, P = 0.022), compared with rs1801274 AG+AA genotypes, rs2736340 CT+TT genotypes or rs4813003 TC+CC genotypes, respectively. Furthermore, a cumulative effect was observed with the ORs being gradually decreased with the increasing accumulative number of non-risk genotypes (Ptrend<0.001). In conclusion, our study suggests that 4 GWAS-identified SNPs, rs2736340, rs4813003, rs3818298 and rs1801274, were nominally associated with KD risk in a Han Chinese population individually and jointly.