FcγR gene copy number in Kawasaki disease and intravenous immunoglobulin treatment response

Pharmacogenomics of coronary artery response to intravenous gamma globulin in kawasaki disease

Kawasaki disease (KD) is a multisystem inflammatory illness of infants and young children that can result in acute vasculitis. The mechanism of coronary artery aneurysms (CAA) in KD despite intravenous gamma globulin (IVIG) treatment is not known. We performed a Whole Genome Sequencing (WGS) association analysis in a racially diverse cohort of KD patients treated with IVIG, both using AHA guidelines. We defined coronary aneurysm (CAA) (N = 234) as coronary z ≥ 2.5 and large coronary aneurysm (CAA/L) (N = 92) as z ≥ 5.0. We conducted logistic regression models to examine the association of genetic variants with CAA/L during acute KD and with persistence >6 weeks using an additive model between cases and 238 controls with no CAA. We adjusted for age, gender and three principal components of genetic ancestry. The top significant variants associated with CAA/L were in the intergenic regions (rs62154092 p < 6.32E-08 most significant). Variants in SMAT4, LOC100127, PTPRD, TCAF2 and KLRC2 were the most significant non-intergenic SNPs. Functional mapping and annotation (FUMA) analysis identified 12 genomic risk loci with eQTL or chromatin interactions mapped to 48 genes. Of these NDUFA5 has been implicated in KD CAA and MICU and ZMAT4 has potential functional implications. Genetic risk score using these 12 genomic risk loci yielded an area under the receiver operating characteristic curve (AUC) of 0.86. This pharmacogenomics study provides insights into the pathogenesis of CAA/L in IVIG-treated KD and shows that genomics can help define the cause of CAA/L to guide management and improve risk stratification of KD patients.

Pharmacogenomics of Coronary Artery Response to Intravenous Gamma Globulin in Kawasaki Disease

Background

Kawasaki disease (KD) is a multisystem inflammatory illness of infants and young children that can result in acute vasculitis. The pathological walls of afflicted coronary arteries show propensity for forming thrombosis and aneurysms. The mechanism of coronary artery aneurysms (CAA) despite intravenous gamma globulin (IVIG) treatment is not known.

Methods

We performed a Whole Genome Sequencing (WGS) association analysis in a racially diverse cohort of KD patients treated with IVIG, both using AHA guidelines. We defined coronary aneurysm (CAA) (N = 234) as coronary z>2.5 and large coronary aneurysm (CAA/L) (N = 92) as z>5.0. We conducted logistic regression models to examine the association of genetic variants with CAA/L during acute KD and with persistence >6 weeks using an additive model between cases and 238 controls with no CAA. We adjusted for age, gender and three principal components of genetic ancestry. We performed functional mapping and annotation (FUMA) analysis and further assessed the predictive risk score of genomic risk loci using the area under the receiver operating characteristic curve (AUC).

Results

The top significant variants associated with CAA/L were in the intergenic regions (rs62154092 p<6.32E-08 most significant). Variants in SMAT4, LOC100127 , PTPRD, TCAF2 and KLRC2 were the most significant non-intergenic SNPs. FUMA identified 12 genomic risk loci with eQTL or chromatin interactions mapped to 48 genes. Of these NDUFA5 has been implicated in KD CAA and MICU and ZMAT4 has potential functional implications. Genetic risk score using these 12 genomic risk loci yielded an AUC of 0.86.

Conclusions

This pharmacogenomics study provides insights into the pathogenesis of CAA/L in IVIG-treated KD patients. We have identified multiple novel SNPs associated with CAA/L and related genes with potential functional implications. The study shows that genomics can help define the cause of CAA/L to guide management and improve risk stratification of KD patients.

Pharmacogenomics of intravenous immunoglobulin response in Kawasaki disease

Introduction

Kawasaki disease (KD) is a diffuse vasculitis in children. Response to high dose intravenous gamma globulin (IVIG), the primary treatment, varies according to genetic background. We sought to identify genetic loci, which associate with treatment response using whole genome sequencing (WGS).

Method

We performed WGS in 472 KD patients with 305 IVIG responders and 167 non-responders defined by AHA clinical criteria. We conducted logistic regression models to test additive genetic effect in the entire cohort and in four subgroups defined by ancestry information markers (Whites, African Americans, Asians, and Hispanics). We performed functional mapping and annotation using FUMA to examine genetic variants that are potentially involved IVIG non-response. Further, we conducted SNP-set [Sequence] Kernel Association Test (SKAT) for all rare and common variants.

Results

Of the 43,288,336 SNPs (23,660,970 in intergenic regions, 16,764,594 in introns and 556,814 in the exons) identified, the top ten hits associated with IVIG non-response were in FANK1, MAP2K3:KCNJ12, CA10, FRG1DP, CWH43 regions. When analyzed separately in ancestry-based racial subgroups, SNPs in several novel genes were associated. A total of 23 possible causal genes were pinpointed by positional and chromatin mapping. SKAT analysis demonstrated association in the entire MANIA2, EDN1, SFMBT2, and PPP2R5E genes and segments of CSMD2, LINC01317, HIVEPI, HSP90AB1, and TTLL11 genes.

Conclusions

This WGS study identified multiple predominantly novel understudied genes associated with IVIG response. These data can serve to inform regarding pathogenesis of KD, as well as lay ground work for developing treatment response predictors.

The state of play in tools for predicting immunoglobulin resistance in Kawasaki disease

INTRODUCTION

Intravenous immunoglobulin (IVIG) resistance is an independent risk factor for the development of coronary artery lesions (CAL) in patients with Kawasaki disease (KD). Accurate identification of IVIG-resistant patients is one of the biggest clinical challenges in the treatment of KD.

AREAS COVERED

In this review article, we will go over current IVIG resistance scoring systems and other biological markers of IVIG resistance, with a particular focus on advances in machine-based learning techniques and high-throughput omics data.

EXPERT OPINION

Traditional scoring models, which were developed using logistic regression, including the Kobayashi score and Egami score, are inadequate at identifying IVIG resistance in non-Japanese populations. Newer machine-learning methods and high-throughput technologies including transcriptomic and epigenetic arrays have identified several potential targets for IVIG resistance including gene expression of the Fc receptor, and components of the interleukin (IL)-1β and pyroptosis pathways. As we enter an age where access to big data has become more commonplace, interpretation of large data sets that are able take into account complexities in patient populations will hopefully usher in a new era of precision medicine, which will enable us to identify and treat KD patients with IVIG resistance with increased accuracy.

The EIF2AK4/rs4594236 AG/GG Genotype Is a Hazard Factor of Immunoglobulin Therapy Resistance in Southern Chinese Kawasaki Disease Patients

Background: Kawasaki disease (KD) is an acute, self-limited vasculitis disorder of unknown etiology in children. Immunologic abnormalities were detected during the acute phase of KD, which reflected that the effect cells of the activated immune system markedly increased cytokine production. High-dose intravenous immunoglobulin (IVIG) therapy is effective in resolving inflammation from KD and reducing occurrence of coronary artery abnormalities. However, 10%–20% of KD patients have no response to IVIG therapy, who were defined as IVIG resistance. Furthermore, these patients have persistent inflammation and increased risk of developing coronary artery aneurysm (CAA). EIF2AK4 is a stress sensor gene and can be activated by pathogen infection. In addition, the polymorphisms of EIF2AK4 were associated with various blood vessel disorders. However, it remains unclear whether the EIF2AK4 gene polymorphisms were related to IVIG therapy outcome in KD patients.

Methods:EIF2AK4/rs4594236 polymorphism was genotyped in 795 IVIG response KD patients and 234 IVIG resistant KD patients through TaqMan, a real-time polymerase chain reaction. The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of association between EIF2AK4/rs4594236 polymorphism and IVIG therapeutic effects.

Results: Our results showed that the EIF2AK4/rs4594236 AG/GG genotype was significantly associated with increased risk to IVIG resistance compared to the AA genotype (AG vs. AA: adjusted ORs = 1.71, 95% CIs = 1.17–2.51, and p = 0.0061; GG vs. AA: adjusted ORs = 2.09, 95% CIs = 1.36–3.23, and p = 0.0009; AG/GG vs. AA: adjusted ORs = 1.82, 95% CIs = 1.27–2.63, and p = 0.0013; and GG vs. AA/AG: adjusted ORs = 1.45, 95% CI = 1.04–2.02, and p = 0.0306). Furthermore, the stratified analysis of age and gender in the KD cohort indicated that male patients carrying the rs4594236 AG/GG genotype tends to be more resistant to IVIG therapy than female patients.

Conclusion: These results suggested that EIF2AK4/rs4594236 polymorphism might be associated with increased risk of IVIG resistance in southern Chinese KD patients.

Epigenetics in Kawasaki Disease

Kawasaki disease (KD) is a common febrile multisystemic inflammatory illness in children that preferentially affects coronary arteries. Children with KD who develop coronary artery aneurysms have a life-long risk of premature coronary artery disease. Hypothesis of inherent predisposition to KD is supported by epidemiological evidence that suggests increased risk of development of disease in certain ethnicities and in children with a previous history of KD in siblings or parents. However, occurrence of cases in clusters, seasonal variation, and very low risk of recurrence suggests an acquired trigger (such as infections) for the development of illness. Epigenetic mechanisms that modulate gene expression can plausibly explain the link between genetic and acquired predisposing factors in KD. Analysis of epigenetic factors can also be used to derive biomarkers for diagnosis and prognostication in KD. Moreover, epigenetic mechanisms can also help in pharmacogenomics with the development of targeted therapies. In this review, we analysed the available literature on epigenetic factors such as methylation, micro-RNAs, and long non-coding RNAs in KD and discuss how these mechanisms can help us better understand the disease pathogenesis and advance the development of new biomarkers in KD.

Identification of increased expression of activating Fc receptors and novel findings regarding distinct IgE and IgM receptors in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is associated with expression and methylation of Fc gamma receptor genes. We characterized immunoglobulin A (IgA), IgE, IgG, and IgM receptor expression levels in KD.

METHODS

Fc receptor expression levels were characterized using GeneChip Human Transcriptome Array 2.0 (HTA 2.0) with 18 KD patients, 18 non-febrile controls, and 18 febrile controls. Another 48 control individuals and 46 patients with KD were measured using pyrosequencing for the methylation levels.

RESULTS

The mRNA expression levels of FCER1A and FCER2 were significantly lower in KD patients than in non-febrile controls and then rose following treatments with intravenous immunoglobulin (IVIG). Expression levels of FCER1G increased compared to the non-febrile subjects and then subsided after IVIG. FCER1A methylation was significantly lower among KD patients and even lower in KD patients with IVIG resistance. HTA analysis revealed higher mRNA levels of FCAR, FCGR1C, and FCGR2A in KD patients. FCMR mRNA expression levels were significantly lower in KD patients. FCMR expression levels rose after IVIG treatment. After IVIG, FCGR1A, B, and C decreased even lower than the febrile controls.

CONCLUSION

This is the first study indicating that IgA, IgE, IgG, and IgM receptors are associated with KD. We highlighted potential biomarkers related to Fc receptors and their regulation.

Relationship between post-IVIG IgG levels and clinical outcomes in Kawasaki disease patients: new insight into the mechanism of action of IVIG

INTRODUCTION/OBJECTIVES

The dosing of intravenous immunoglobulin (IVIG) therapy for Kawasaki disease (KD) has been a matter of debate for decades, with recent studies implicating that larger doses lead to better outcomes. Despite this, few have investigated post-IVIG infusion immunoglobulin G (IgG) levels in relation to outcomes of KD such as response to IVIG and development of coronary artery abnormalities (CAAs). The present study investigated how varying levels of post-infusion IgG affected these outcomes.

METHOD

We collected demographic and laboratory data, including post-infusion IgG, from children with KD who were admitted to six hospitals in Japan between 2006 and 2012. We conducted multivariate analyses to examine the relationship between independent variables and non-response to IVIG and development of CAAs. We used random forest, a decision tree-based machine learning tool, to investigate the marginal effect of varying post-infusion IgG levels on non-response to IVIG and development of CAAs.

RESULTS

Of 456 patients included in the study, 130 (28.5%) were non-responders and 38 (8.3%) developed CAAs. Sodium, post-infusion IgG, and AST were significantly associated with non-response. Post-infusion IgG and sodium were significantly associated with CAA development. The random forest plots revealed a decrease in non-response and CAA rates with increasing post-infusion IgG until post-infusion IgG was near the median (2821 mg/dL), after which the non-response and CAA rates leveled off.

CONCLUSIONS

Greater post-infusion IgG is associated with better response to IVIG and decreased CAA development in KD patients, but this effect levels off at post-infusion IgG levels greater than the median. Key points • Though previous studies have shown that post-intravenous immunoglobulin (IVIG) infusion immunoglobulin G (IgG) is associated with non-response to IVIG therapy and coronary artery abnormality (CAA) development in Kawasaki disease (KD) patients, no study has investigated the relationship between varying levels of post-infusion IgG and these clinical outcomes. • Our study showed that non-response to IVIG therapy and CAA development in Kawasaki disease patients follow a decreasing trend with increasing post-infusion IgG at post-infusion IgG levels below the median. • At values of post-infusion IgG greater than the median, non-response and CAA development rates remain relatively constant with increasing post-infusion IgG. • Our study suggests that when post-infusion IgG is greater than the median, IgG may have fully bound to the therapeutic targets of KD, and in these patients, there may be limited benefit in administering additional IVIG.

Association of the IL16 Asn1147Lys polymorphism with intravenous immunoglobulin resistance in Kawasaki disease

Kawasaki disease (KD) is an acute, self-limited vasculitis, mainly affecting children younger than 5 years old, with accompanying fever and signs of mucocutaneous inflammation. Intravenous immunoglobulin (IVIG) is the standard treatment for KD; however, ~15% of patients are resistant to IVIG treatment. To identify protein coding genetic variants influencing IVIG resistance, we re-analyzed our previous genome-wide association study (GWAS) data from 296 patients with KD, including 101 IVIG non-responders and 195 IVIG responders. Five nonsynonymous SNPs (nsSNPs) in five immune-related genes, including a previously reported SAMD9L nsSNP (rs10488532; p.Val266Ile), were associated with IVIG non-response (odds ratio [OR] = 1.89-3.46, P = 0.0109-0.0035). In a replication study of the four newly-identified nsSNPs, only one in the interleukin 16 (IL16) gene (rs11556218, p.Asn1147Lys) showed a trend of association with IVIG non-response (OR = 1.54, P = 0.0078). The same IL16 nsSNP was more significantly associated with IVIG non-response in combined analysis of all data (OR = 1.64, P = 1.25 × 10^-4). Furthermore, risk allele combination of the IL16 CT and SAMD9L TT nsSNP genotypes exhibited a very strong effect size (OR = 9.19, P = 3.63 × 10^-4). These results implicate IL16 as involved in the mechanism of IVIG resistance in KD.

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.

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.

Leveraging Genetic Findings for Precision Medicine in Vasculitis

Vasculitides are a heterogeneous group of low frequent disorders, mainly characterized by the inflammation of blood vessels that narrows or occlude the lumen and limits the blood flow, leading eventually to significant tissue and organ damage. These disorders are classified depending on the size of the affected blood vessels in large, medium, and small vessel vasculitis. Currently, it is known that these syndromes show a complex etiology in which both environmental and genetic factors play a major role in their development. So far, these conditions are not curable and the therapeutic approaches are mainly symptomatic. Moreover, a percentage of the patients do not adequately respond to standard treatments. Over the last years, numerous genetic studies have been carried out to identify susceptibility loci and biological pathways involved in vasculitis pathogenesis as well as potential genetic predictors of treatment response. The ultimate goal of these studies is to identify new therapeutic targets and to improve the use of existing drugs to achieve more effective treatments. This review will focus on the main advances made in the field of genetics and pharmacogenetics of vasculitis and their potential application for ameliorating long-term outcomes in patient management and in the development of precision medicine.

Identification of SAMD9L as a susceptibility locus for intravenous immunoglobulin resistance in Kawasaki disease by genome-wide association analysis

Kawasaki disease (KD) is a systemic vasculitis affecting infants and children; it manifests as fever and signs of mucocutaneous inflammation. Intravenous immunoglobulin (IVIG) treatment effectively attenuates the fever and systemic inflammation. However, 10-20% patients are unresponsive to IVIG. To identify genetic variants influencing IVIG non-response in KD, a genome-wide association study (GWAS) and a replication study were performed using a total of 148 IVIG non-responders and 845 IVIG-responders in a Korean population. rs28662 in the sterile alpha motif domain-containing protein 9-like (SAMD9L) locus showed the most significant result in the joint analysis of GWAS and replication samples (odds ratio (OR) = 3.47, P = 1.39 × 10^-5). The same SNP in the SAMD9L locus was tested in the Japanese population, and it revealed a more significant association in a meta-analysis with Japanese data (OR = 4.30, P = 5.30 × 10^-6). These results provide new insights into the mechanism of IVIG response in KD.

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.

Polymorphisms of immunoglobulin receptors and the effects on clinical outcome in cancer immunotherapy and other immune diseases: a general review

Receptors for the Fc domain of immunoglobulins [Fc receptors (FcRs)] are essential for the maintenance of antibody-mediated immune responses. FcRs consist of activating- and inhibitory-type receptors that regulate adequate thresholds for various immune cells. In particular, polymorphisms and/or gene copy-number variations of FcRs for IgG (FcγRs) are closely associated with the development of inflammatory disorders, including autoimmune diseases. Recent evidence has implicated polymorphisms of FcRs in the efficacy of monoclonal antibody (mAb)-mediated therapy. This review provides an overview of genetic variations in human FcγRs and the clinical contribution of FcγR polymorphisms in mAb treatments for cancer, autoimmune diseases and allergies.

The effect of FcγRIIA and FcγRIIB on coronary artery lesion formation and intravenous immunoglobulin treatment responses in children with Kawasaki disease

Previous research has found patients with the FcγRIIIB NA1 variant having increased risk of intravenous immunoglobulin (IVIG) resistance in Kawasaki disease (KD). Our previous studies revealed that elevated FcγRIIA expression correlated with the susceptibility of KD patients. We conducted this research to determine whether and how Fcγ receptors affect the susceptibility, IVIG treatment response, and coronary artery lesions (CAL) of KD patients. The activating FcγRIIA and inhibitory FcγRIIB methylation levels of seven patients with KD and four control subjects were examined using HumanMethylation27 BeadChip. We enrolled a total of 44 KD patients and 10 control subjects with fevers. We performed real-time RT-PCR to determine the FcγRIIA and FcγRIIB expression levels, as well as a luciferase assay of FcγRIIA. We found a considerable increase in methylation of both FcγRIIA and FcγRIIB in KD patients undergoing IVIG treatment. Promoter methylation of FcγRIIA inhibited reporter activity in K562 cells using luciferase assay. The FcγRIIB mRNA expression levels were not found to increase susceptibility, CAL formation, or IVIG resistance. FcγRIIA mRNA expression levels were significantly higher in IVIG-resistant patients than in those that responded to IVIG during the pre-treatment period. Furthermore, the FcγRIIA/IIB mRNA expression ratio was considerably higher in KD patients with CAL than in those without CAL. FcγRIIA and FcγRIIB both demonstrated increased methylation levels in KD patients that underwent IVIG treatment. FcγRIIA expression influenced the IVIG treatment response of KD patients. The FcγRIIA/IIB mRNA expression ratio was greater in KD patients with CAL formation.

Expression of Fc<gamma>Rs on monocytes among Kawasaki disease patients with coronary artery lesions

OBJECTIVE

To study expression of Fc gamma receptors (Fc<gamma>Rs) on monocytes in Kawasaki disease (KD) patients with coronary artery lesions (CAL).

METHODS

160 newly diagnosed KD patients and 80 health children were enrolled in this study. All patients were scheduled to receive both aspirin and intravenous immunoglobulin (IVIG). Serial blood samples were obtained before and 3days after completing IVIG therapy. The first two-dimensional echocardiographic examination was performed for all KD patients within 10days, and was repeated at 3weeks. CAL was defined by coronary artery Z-scores≥2.5 by echocardiography. Expression of inhibitory and activating Fc<gamma>Rs on CD14⁺ monocytes (MCs) was assessed by flow cytometry. Cytokine expression in MC was evaluated by PCR.

RESULTS

Of the 160KD patients enrolled in this study, 36 had coronary artery lesions (KD-CAL⁺ group), while 124 did not (KD-CAL^- group). There was no significant difference in Fc<gamma>RI expression on MCs from KD patients and that of Ctrls. Although Fc<gamma>RIII and Fc<gamma>RIIa levels were significantly higher in KD patients compared with those in Ctrls, there were no significant differences between the KD-CAL⁺ and KD-CAL^- groups. Fc<gamma>RIIb expression in the KD patients was lower than that of Ctrls, meanwhile expression in the KD-CAL⁺ group was lower than that in the KD-CAL^- group. After IVIG therapy, Fc<gamma>RIIb expression increased in KD-CAL⁺, but did not reach the normal range. A negative correlation was observed between the levels of IL-6, TNF-α and Fc<gamma>RIIb expression.

CONCLUSION

Decreased Fc<gamma>RIIb expression on MCs may contribute to the development of coronary artery lesions in patients with KD.

Copy number variation of FCGR genes in etiopathogenesis of sarcoidosis

We have previously revealed that, in contrast to polymorphism of FCGR2B and FCGR3B, polymorphism of FCGR2A, FCGR2C and FCGR3A genes, encoding receptors for Fc fragment of immunoglobulin G (Fcγ receptors), play a role in increased level of circulating immune complexes with occurrence of Mycobacterium tuberculosis heat shock proteins in patients with sarcoidosis. However, this immunocomplexemia might also be caused by decreased clearance by immune cells due to a changed copy number of FCGR genes. Thus, the next step of our study was to evaluate copy number variation of FCGR2A, FCGR2B, FCGR2C, FCGR3A and FCGR3B in this disease. The analysis was carried out by real-time quantitative PCR on 104 patients and 110 healthy volunteers. Despite previously detected variation in allele/genotype frequencies of FCGR in sarcoidosis and its particular stages, there was no copy number variation of the tested genes between sarcoidosis or its stages and healthy control, as well as between stages themselves. A relevant increase in copy number of FCGR2C and FCGR3B in Stage IV of sarcoidosis vs. other stages and controls was detected, but this observation was based on a limited number of Stage IV patients. Hence, polymorphism of FCGR genes seems to be more important than their copy number variation in etiopathogenesis of sarcoidosis in patients from the Polish population.

Imputation of class I and II HLA loci using high-density SNPs from ImmunoChip and their associations with Kawasaki disease in family-based study

Kawasaki disease (KD) is the leading cause of acquired heart disease in children in most developed countries including the United States. The etiology of KD is not known; however, epidemiological and immunological data suggest infectious or immune-related factors in the manifestation of the disease. Further, KD has several hereditary features that strongly suggest a genetic component to disease pathogenesis. Human leucocyte antigen (HLA) loci have also been reported to be associated with KD, but results have been inconsistent, in part, because of small study samples and varying linkage disequilibrium (LD) patterns observed across different ethnic groups. To maximize the informativeness of single nucleotide polymorphism (SNP) genotypes in the major histocompatibility (MHC) region, we imputed classical HLA I (A, B, C) and HLA II (DRB1, DQA1, DQB1) alleles using SNP2HLA method from genotypes of 6700 SNPs within the extended MHC region contained in the ImmunoChip among 112 White patients with KD and their biological parents from North America and tested their association with KD susceptibility using the transmission disequilibrium test. Mendelian consistency in the trios suggested high accuracy and reliability of the imputed alleles (class I = 97.5%, class II = 96.6%). While several SNPs in the MHC region were individually associated with KD susceptibility, we report over-transmission of HLA-C*15 (z = +2.19, P = 0.03) and under-transmission of HLA-B*44 (z = -2.49, P = 0.01) alleles from parents to patients with KD. HLA-B*44 has been associated with KD in other smaller studies, and both HLA-C*15 and HLA-B*44 have biological mechanisms that could potentially be involved in KD pathogenesis. Overall, inferring HLA loci within the same ethnic group, using family-based information is a powerful approach. However, studies with larger sample sizes are warranted to evaluate the correlations of the strength and directions between the SNPs in MHC region and the imputed HLA alleles with KD.

Is dosing of therapeutic immunoglobulins optimal? A review of a three-decade long debate in europe

The consumption of immunoglobulins (Ig) is increasing due to better recognition of antibody deficiencies, an aging population, and new indications. This review aims to examine the various dosing regimens and research developments in the established and in some of the relevant off-label indications in Europe. The background to the current regulatory settings in Europe is provided as a backdrop for the latest developments in primary and secondary immunodeficiencies and in immunomodulatory indications. In these heterogeneous areas, clinical trials encompassing different routes of administration, varying intervals, and infusion rates are paving the way toward more individualized therapy regimens. In primary antibody deficiencies, adjustments in dosing and intervals will depend on the clinical presentation, effective IgG trough levels and IgG metabolism. Ideally, individual pharmacokinetic profiles in conjunction with the clinical phenotype could lead to highly tailored treatment. In practice, incremental dosage increases are necessary to titrate the optimal dose for more severely ill patients. Higher intravenous doses in these patients also have beneficial immunomodulatory effects beyond mere IgG replacement. Better understanding of the pharmacokinetics of Ig therapy is leading to a move away from simplistic "per kg" dosing. Defective antibody production is common in many secondary immunodeficiencies irrespective of whether the causative factor was lymphoid malignancies (established indications), certain autoimmune disorders, immunosuppressive agents, or biologics. This antibody failure, as shown by test immunization, may be amenable to treatment with replacement Ig therapy. In certain immunomodulatory settings [e.g., idiopathic thrombocytopenic purpura (ITP)], selection of patients for Ig therapy may be enhanced by relevant biomarkers in order to exclude non-responders and thus obtain higher response rates. In this review, the developments in dosing of therapeutic immunoglobulins have been limited to high and some medium priority indications such as ITP, Kawasaki' disease, Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy, myasthenia gravis, multifocal motor neuropathy, fetal alloimmune thrombocytopenia, fetal hemolytic anemia, and dermatological diseases.

High-density genotyping of immune loci in Kawasaki disease and IVIG treatment response in European-American case-parent trio study

Kawasaki disease (KD) is a diffuse and acute small-vessel vasculitis observed in children, and has genetic and autoimmune components. We genotyped 112 case-parent trios of European decent (confirmed by ancestry informative markers) using the immunoChip array, and performed association analyses with susceptibility to KD and intravenous immunoglobulin (IVIG) non-response. KD susceptibility was assessed using the transmission disequilibrium test, whereas IVIG non-response was evaluated using multivariable logistic regression analysis. We replicated single-nucleotide polymorphisms (SNPs) in three gene regions (FCGR, CD40/CDH22 and HLA-DQB2/HLA-DOB) that have been previously associated with KD and provide support to other findings of several novel SNPs in genes with a potential pathway in KD pathogenesis. SNP rs838143 in the 3'-untranslated region of the FUT1 gene (2.7 × 10(-5)) and rs9847915 in the intergenic region of LOC730109 | BRD7P2 (6.81 × 10(-7)) were the top hits for KD susceptibility in additive and dominant models, respectively. The top hits for IVIG responsiveness were rs1200332 in the intergenic region of BAZ1A | C14orf19 (1.4 × 10(-4)) and rs4889606 in the intron of the STX1B gene (6.95 × 10(-5)) in additive and dominant models, respectively. Our study suggests that genes and biological pathways involved in autoimmune diseases have an important role in the pathogenesis of KD and IVIG response mechanism.

European consensus proposal for immunoglobulin therapies

The use of immunoglobulin (Ig) preparations (intravenous, IVIg, subcutaneous, SCIg) for replacement and immunomodulation therapy worldwide has tripled in the past 20 years and represents an ever-increasing cost factor for healthcare organizations. The limited access to the starting material of this essential medicinal product is currently the driving force for human plasma collection. Increasing awareness and improved diagnosis of human primary immunodeficiencies and a broadening of immunomodulatory indications are responsible for this development, and on a longer run might lead to plasma supply shortages. Consensus recommendations for the optimal use of Ig in clinical practice, including priority rankings for the most urgent indications, are therefore urgently needed. During a recent meeting in Kreuth, Germany, expert nominees from 36 Council of Europe states, together with colleagues from observer countries and regulatory agencies came up with this consensus statement.

Intravenous immunoglobulin, pharmacogenomics, and Kawasaki disease

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology and it is therefore worth examining the multifactorial interaction of genes and environmental factors. Targeted genetic association and genome-wide association studies have helped to provide a better understanding of KD from infection to the immune-related response. Findings in the past decade have contributed to a major breakthrough in the genetics of KD, with the identification of several genomic regions linked to the pathogenesis of KD, including ITPKC, CD40, BLK, and FCGR2A. This review focuses on the factors associated with the genetic polymorphisms of KD and the pharmacogenomics of the response to treatment in patients with intravenous immunoglobulin resistance.

Contribution of Human FcγRs to Disease with Evidence from Human Polymorphisms and Transgenic Animal Studies

The biological activities of human IgG antibodies predominantly rely on a family of receptors for the Fc portion of IgG, FcγRs: FcγRI, FcγRIIA, FcγRIIB, FcγRIIC, FcγRIIIA, FcγRIIIB, FcRL5, FcRn, and TRIM21. All FcγRs bind IgG at the cell surface, except FcRn and TRIM21 that bind IgG once internalized. The affinity of FcγRs for IgG is determined by polymorphisms of human FcγRs and ranges from 2 × 10⁴ to 8 × 10⁷ M⁻¹. The biological functions of FcγRs extend from cellular activation or inhibition, IgG-internalization/endocytosis/phagocytosis to IgG transport and recycling. This review focuses on human FcγRs and intends to present an overview of the current understanding of how these receptors may contribute to various pathologies. It will define FcγRs and their polymorphic variants, their affinity for human IgG subclasses, and review the associations found between FcγR polymorphisms and human pathologies. It will also describe the human FcγR-transgenic mice that have been used to study the role of these receptors in autoimmune, inflammatory, and allergic disease models.

DC-SIGN gene promoter variants and IVIG treatment response in Kawasaki disease

BACKGROUND

Genetic variants in the inhibiting FcγRIIB mediate anti-inflammatory responses and influence IVIG refractoriness (IVIG-R). However, these variants are rare in Asian and Hispanic populations so other genes in the pathway could be potentially involved. IVIG is ineffective in mice lacking SIGN-R1, a related molecule to human DC-SIGN. Further, DC-SIGN is a known receptor for sialylated Fc, the component responsible for the anti-inflammatory action of IVIG. Thus, we hypothesized that DC-SIGN would also be involved in the pathway of IVIG response in Kawasaki Disease (KD) patients.

FINDINGS

A case-control approach was performed to examine the differential distribution of five single nucleotide polymorphisms (SNPs) in DC-SIGN promoter with IVIG-R among White (158 vs. 62), Asian (64 vs. 12) and Hispanic (55 vs. 20) KD patients. Distinct differences in allele frequency distributions of several variants in the DC-SIGN promoter were observed in the three ethnic groups. Further, Asians with the major allele "A" in rs2287886 were more likely (OR = 1.76, p = 0.04) to be IVIG non-responder, but this allele is a minor allele in other two ethnic groups, where the association was not apparent.

CONCLUSIONS

DC-SIGN can potentially complement the role of FcγRIIB in the anti-inflammatory cascade involved in the IVIG response mechanism.