Functional Fcgamma receptor polymorphisms are associated with human allergy

Multi-omic integration reveals alterations in nasal mucosal biology that mediate air pollutant effects on allergic rhinitis

BACKGROUND

Allergic rhinitis is a common inflammatory condition of the nasal mucosa that imposes a considerable health burden. Air pollution has been observed to increase the risk of developing allergic rhinitis. We addressed the hypotheses that early life exposure to air toxics is associated with developing allergic rhinitis, and that these effects are mediated by DNA methylation and gene expression in the nasal mucosa.

METHODS

In a case-control cohort of 505 participants, we geocoded participants' early life exposure to air toxics using data from the US Environmental Protection Agency, assessed physician diagnosis of allergic rhinitis by questionnaire, and collected nasal brushings for whole-genome DNA methylation and transcriptome profiling. We then performed a series of analyses including differential expression, Mendelian randomization, and causal mediation analyses to characterize relationships between early life air toxics, nasal DNA methylation, nasal gene expression, and allergic rhinitis.

RESULTS

Among the 505 participants, 275 had allergic rhinitis. The mean age of the participants was 16.4 years (standard deviation = 9.5 years). Early life exposure to air toxics such as acrylic acid, phosphine, antimony compounds, and benzyl chloride was associated with developing allergic rhinitis. These air toxics exerted their effects by altering the nasal DNA methylation and nasal gene expression levels of genes involved in respiratory ciliary function, mast cell activation, pro-inflammatory TGF-β1 signaling, and the regulation of myeloid immune cell function.

CONCLUSIONS

Our results expand the range of air pollutants implicated in allergic rhinitis and shed light on their underlying biological mechanisms in nasal mucosa.

Interleukin-13 Treatment of Living Lung Tissue Model Alters the Metabolome and Proteome-A Nano-DESI MS Metabolomics and Shotgun Proteomics Study

Asthma is a chronic respiratory disease with one of the largest numbers of cases in the world; thus, constant investigation and technical development are needed to unravel the underlying biochemical mechanisms. In this study, we aimed to develop a nano-DESI MS method for the in vivo characterization of the cellular metabolome. Using air-liquid interface (ALI) cell layers, we studied the role of Interleukin-13 (IL-13) on differentiated lung epithelial cells acting as a lung tissue model. We demonstrate the feasibility of nano-DESI MS for the in vivo monitoring of basal-apical molecular transport, and the subsequent endogenous metabolic response, for the first time. Conserving the integrity of the ALI lung-cell layer enabled us to perform temporally resolved metabolomic characterization followed by "bottom-up" proteomics on the same population of cells. Metabolic remodeling was observed upon histamine and corticosteroid treatment of the IL-13-exposed lung cell monolayers, in correlation with alterations in the proteomic profile. This proof of principle study demonstrates the utility of in vivo nano-DESI MS for characterizing ALI tissue layers, and the new markers identified in our study provide a good starting point for future, larger-scale studies.

Acute neutrophilic vasculitis (leukocytoclasia) in 36 COVID-19 autopsy brains

BACKGROUND

Hypercytokinemia, the renin-angiotensin system, hypoxia, immune dysregulation, and vasculopathy with evidence of immune-related damage are implicated in brain morbidity in COVID-19 along with a wide variety of genomic and environmental influences. There is relatively little evidence of direct SARS-CoV-2 brain infection in COVID-19 patients.

METHODS

Brain histopathology of 36 consecutive autopsies of patients who were RT-PCR positive for SARS-CoV-2 was studied along with findings from contemporary and pre-pandemic historical control groups. Immunostaining for serum and blood cell proteins and for complement components was employed. Microcirculatory wall complement deposition in the COVID-19 cohort was compared to historical control cases. Comparisons also included other relevant clinicopathological and microcirculatory findings in the COVID-19 cohort and control groups.

RESULTS

The COVID-19 cohort and both the contemporary and historical control groups had the same rate of hypertension, diabetes mellitus, and obesity. The COVID-19 cohort had varying amounts of acute neutrophilic vasculitis with leukocytoclasia in the microcirculation of the brain in all cases. Prominent vascular neutrophilic transmural migration was found in several cases and 25 cases had acute perivasculitis. Paravascular microhemorrhages and petechial hemorrhages (small brain parenchymal hemorrhages) had a slight tendency to be more numerous in cohort cases that displayed less acute neutrophilic vasculitis. Tissue burden of acute neutrophilic vasculitis with leukocytoclasia was the same in control cases as a group, while it was significantly higher in COVID-19 cases. Both the tissue burden of acute neutrophilic vasculitis and the activation of complement components, including membrane attack complex, were significantly higher in microcirculatory channels in COVID-19 cohort brains than in historical controls.

CONCLUSIONS

Acute neutrophilic vasculitis with leukocytoclasia, acute perivasculitis, and associated paravascular blood extravasation into brain parenchyma constitute the first phase of an immune-related, acute small-vessel inflammatory condition often termed type 3 hypersensitivity vasculitis or leukocytoclastic vasculitis. There is a higher tissue burden of acute neutrophilic vasculitis and an increased level of activated complement components in microcirculatory walls in COVID-19 cases than in pre-pandemic control cases. These findings are consistent with a more extensive small-vessel immune-related vasculitis in COVID-19 cases than in control cases. The pathway(s) and mechanism for these findings are speculative.

Influence of Genetics on the Response to Omalizumab in Patients with Severe Uncontrolled Asthma with an Allergic Phenotype

Omalizumab is a monoclonal antibody indicated for the treatment of severe uncontrolled asthma with an allergic phenotype. Its effectiveness could be influenced by clinical variables and single nucleotide polymorphisms (SNPs) in one or more of the genes involved in the mechanism of action and process of response to omalizumab, and these could be used as predictive biomarkers of response. We conducted an observational retrospective cohort study that included patients with severe uncontrolled allergic asthma treated with omalizumab in a tertiary hospital. Satisfactory response after 12 months of treatment was defined as (1) Reduction ≥ 50% of exacerbations or no exacerbations, (2) Improvement of lung function ≥ 10% FEV1, and (3) Reduction ≥ 50% of OCS courses or no OCS. Polymorphisms in the FCER1A (rs2251746, rs2427837), FCER1B (rs1441586, rs573790, rs1054485, rs569108), C3 (rs2230199), FCGR2A (rs1801274), FCGR2B (rs3219018, rs1050501), FCGR3A (rs10127939, rs396991), IL1RL1 (rs1420101, rs17026974, rs1921622), and GATA2 (rs4857855) genes were analyzed by real-time polymerase chain reaction (PCR) using TaqMan probes. A total of 110 patients under treatment with omalizumab were recruited. After 12 months of treatment, the variables associated with a reduction in exacerbations were the absence of polyposis (odds ratio [OR] = 4.22; 95% confidence interval [CI] = 0.95-19.63), IL1RL1 rs17026974-AG (OR = 19.07; 95% CI = 1.27-547), and IL1RL1 rs17026974-GG (OR = 16.76; 95% CI = 1.22-438.76). Reduction in oral corticosteroids (OCS) was associated with age of starting omalizumab treatment (OR = 0.95; 95% CI = 0.91-0.99) and blood eosinophil levels > 300 cells/µL (OR = 2.93; 95% CI = 1.01-9.29). Improved lung function showed a relationship to the absence of chronic obstructive pulmonary disease (COPD) (OR = 12.16; 95% CI = 2.45-79.49), FCGR2B rs3219018-C (OR = 8.6; 95% CI = 1.12-117.15), GATA2 rs4857855-T (OR = 15.98; 95% CI = 1.52-519.57) and FCGR2A rs1801274-G (OR = 13.75; 95% CI = 2.14-142.68; AG vs. AA and OR = 7.46; 95% CI = 0.94-89.12; GG vs. AA). Meeting one response criterion was related to FCER1A rs2251746-TT (OR = 24; 95% CI = 0.77-804.57), meeting two to age of asthma diagnosis (OR = 0.93; 95% CI = 0.88-0.99), and meeting all three to body mass index (BMI) < 25 (OR = 14.23; 95% CI = 3.31-100.77) and C3 rs2230199-C (OR = 3; 95% CI = 1.01-9.92). The results of this study show the possible influence of the polymorphisms studied on the response to omalizumab and the clinical benefit that could be obtained by defining predictive biomarkers of treatment response.

Coronin-1A serves as a serum biomarker for supportive diagnosis of Mycobacterium tuberculosis infection

Introduction

The severity and spread of tuberculosis, a major burden, can be prevented by more rapid and accurate laboratory diagnosis. The purpose of this study is to systematically explore candidate serum proteins in patients with Mycobacterium tuberculosis infection for further application as novel biomarkers.

Methods

Our study was performed in two major steps: screening of the literature for potential biomarkers, and then validation of their levels in patients and controls. Many serum/plasma proteins previously reported to be abnormally expressed in patients with tuberculosis between 2012 and 2021 were comprehensively assembled. The biological role in tuberculosis was also predicted for each using the bioinformatics tool STRING. Candidate proteins found to have the same expression in other related diseases were excluded. Subsequently, the serum level of the candidate serum/plasma protein that met the aforementioned criteria was validated by sandwich ELISA; diagnostic performance was analysed by the area under the curve (AUC) of the receiver operating characteristic (ROC).

Results

From 103 collected serum/plasma proteins, coronin-1A was found to have abnormal expression only in patients with tuberculosis and was associated with tuberculosis. In addition, the validation of coronin-1A in the serum of patients with pulmonary tuberculosis revealed a higher level than in that of healthy individuals. Furthermore, the area under the ROC curve for diagnostic power of coronin-1A was 0.866, with high sensitivity and specificity at a cut-point of approximately 52.7 ng/mL.

Conclusions

We concluded that the level of serum coronin-1A might serve as a novel biomarker for alternative laboratory examination to effectively distinguish patients with tuberculosis from those with other related diseases and healthy individuals.

Polymorphisms in the FCER2 gene have associations with asthma and chronic obstructive pulmonary disease

Background

Asthma and chronic obstructive pulmonary disease (COPD) are heterogenetic diseases and exhibit many similarities. Dutch hypothesis proposed that these two diseases may have common genetic origins. This study aims to investigate whether asthma and COPD share a common genetic background in Chinese patients.

Methods

In this case-control study, single nucleotide polymorphisms (SNPs) were genotyped using SNaPshot. Haplotype disease analysis and haplotype phenotype analysis were applied to assess the relationship between three polymorphisms of the FCER2 gene and the risk of COPD/asthma. Additionally, associations between polymorphisms of the FCER2 gene and phenotypes were analyzed.

Results

We detected ten SNPs of seven genes (FCER1A, FCGR2A, FCGR2B, CHI3L1, ADRB2, STAT6, and FCER2) expressed by airway epithelial cells. We detected genotypes and allele distributions in 251 COPD patients, 597 asthma patients, and 632 healthy controls. A significant difference was found in the FCER2 gene (rs28364072) between COPD patients and controls (P=0.009). Significant differences were observed in the genotype and allele distributions of rs1801274 (FCGR2A), rs12368672 (STAT6), and rs2228137 (FCER2) between asthma patients and controls (P=0.004, 0.007 and 0.010, respectively). Notably, polymorphisms of FCER2 gene were associated with the risk of both COPD (P=0.009 for rs28364072) and asthma (P=0.01 for rs2228137). Haplotype analysis revealed that haplotype T-G-T (alleles of rs28364072, rs2228137, and rs3760687, respectively) was significantly associated with a higher risk of asthma [odds ratios (OR) =2.25, 95% confidence interval (CI): 1.26-4.01, P=0.006]. Further analysis showed that the C-A-C haplotype and C-G-T haplotype were associated with increased blood eosinophils in either COPD or asthma patients (P=0.034, and P<0.001, respectively). Moreover, haplotypes C-A-C, C-G-C, and T-G-C showed significant associations with serum IgE levels in asthma patients (P=0.002, 0.041, and 0.004, respectively).

Conclusions

Our data suggest that the FCER2 gene might associate with predisposition to asthma and COPD, while FCER2 haplotypes were associated with pulmonary function measurements and blood eosinophils counts in both diseases. Our findings support the common genetic basis for asthma and COPD, suggesting a potential therapeutic target for the two diseases.

An accurate genetic assay to identify human neutrophil antigen 2 deficiency

OBJECTIVE

We aimed to develop accurate and user-friendly genetic assays to identify the inherited neutrophil antigen-2 (HNA-2) deficiency in humans.

BACKGROUND

HNA-2 is one of the most important neutrophil antigens implicated in a number of human disorders. HNA-2 deficiency or HNA-2 null is a common phenotype observed in 3%-5% Americans. HNA-2 null individuals are at risk to produce isoantibodies (or alloantibodies) that play important roles in transfusion-related acute lung injury, immune neutropenia, and bone marrow graft failure. We previously demonstrated that the CD177 coding SNP 787A > T (c.787A > T) is the most important genetic determinant for HNA-2 deficiency. However, reliable genetic assays are not available for routine clinical laboratory application up to now.

STUDY DESIGN AND METHODS

A novel polymerase chain reaction (PCR) strategy was used to determine genotypes of the CD177 SNP c.787A > T. In the simplified PCR assay, all allele specific primers and internal control primers were included in the same reaction, which ensures reliability of the assay. In addition, a novel high-throughput nested TaqMan assay was developed to determine genotypes of c.787A > T for large population genetic analysis of HNA-2 deficiency.

RESULTS

CD177 SNP c787A > T genotypes of 396 subjects were 100% concordant among the single PCR reaction method, the nested TaqMan assay, and Sanger Sequencing analysis. Out of 396 subjects, all 18 donors with the CD177 STP homozygous genotype were HNA-2 null.

CONCLUSION

The novel PCR-based genotyping assay is accurate to identify HNA-2 deficient individuals and is suitable for clinical laboratories. In addition, the innovative high-throughput nested TaqMan assay will be useful for large-scale population screens and genetic studies of HNA-2 deficiency.

Cross-Linking Cellular Prion Protein Induces Neuronal Type 2-Like Hypersensitivity

Background

Previous reports identified proteins associated with ‘apoptosis’ following cross-linking PrP^C with motif-specific anti-PrP antibodies in vivo and in vitro. The molecular mechanisms underlying this IgG-mediated neurotoxicity and the role of the activated proteins in the apoptotic pathways leading to neuronal death has not been properly defined. Previous reports implicated a number of proteins, including apolipoprotein E, cytoplasmic phospholipase A2, prostaglandin and calpain with anti-PrP antibody-mediated ‘apoptosis’, however, these proteins are also known to play an important role in allergy. In this study, we investigated whether cross-linking PrP^C with anti-PrP antibodies stimulates a neuronal allergenic response.

Methods

Initially, we predicted the allergenicity of the epitope sequences associated with ‘neurotoxic’ anti-PrP antibodies using allergenicity prediction servers. We then investigated whether anti-PrP antibody treatment of mouse primary neurons (MPN), neuroblastoma cells (N2a) and microglia (N11) cell lines lead to a neuronal allergenic response.

Results

In-Silico studies showed that both tail- and globular-epitopes were allergenic. Specifically, binding regions that contain epitopes for previously reported ‘neurotoxic’ antibodies such as ICSM18 (146-159), ICSM35 (91-110), POM 1 (138-147) and POM 3 (95-100) lead to activation of allergenic related proteins. Following direct application of anti-PrP^C antibodies on N2a cells, we identified 4 neuronal allergenic-related proteins when compared with untreated cells. Furthermore, we identified 8 neuronal allergenic-related proteins following treatment of N11 cells with anti-PrP^C antibodies prior to co-culture with N2a cells when compared with untreated cells. Antibody treatment of MPN or MPN co-cultured with antibody-treated N11 led to identifying 10 and 7 allergenic-related proteins when compared with untreated cells. However, comparison with 3F4 antibody treatment revealed 5 and 4 allergenic-related proteins respectively. Of importance, we showed that the allergenic effects triggered by the anti-PrP antibodies were more potent when antibody-treated microglia were co-cultured with the neuroblastoma cell line. Finally, co-culture of N2a or MPN with N11-treated with anti-PrP antibodies resulted in significant accumulation of NO and IL6 but not TNF-α in the cell culture media supernatant.

Conclusions

This study showed for the first time that anti-PrP antibody binding to PrP^C triggers a neuronal hypersensitivity response and highlights the important role of microglia in triggering an IgG-mediated neuronal hypersensitivity response. Moreover, this study provides an important impetus for including allergenic assessment of therapeutic antibodies for neurodegenerative disorders to derive safe and targeted biotherapeutics.

Allergic Aspects of IgG4-Related Disease: Implications for Pathogenesis and Therapy

IgG4-related disease (IgG4-RD) is a rare systemic fibroinflammatory disease frequently associated with allergy. The pathogenesis of IgG4-RD is poorly understood, and effective therapies are limited. However, IgG4-RD appears to involve some of the same pathogenic mechanisms observed in allergic disease, such as T helper 2 (Th2) and regulatory T cell (Treg) activation, IgG4 and IgE hypersecretion, and blood/tissue eosinophilia. In addition, IgG4-RD tissue fibrosis appears to involve activation of basophils and mast cells and their release of alarmins and cytokines. In this article, we review allergy-like features of IgG4-RD and highlight targeted therapies for allergy that have potential in treating patients with IgG4-RD.

Epigenome-scale comparison of DNA methylation between blood leukocytes and bronchial epithelial cells

Aim: Agreement in DNA methylation (DNAm) at the genome scale between blood leukocytes (BL) and bronchial epithelial cells (BEC) is unknown. We examine as to what extent DNAm in BL is comparable with that in BEC and serves as a surrogate for BEC. Materials & methods: Overall agreement (paired t-tests with false discovery rate adjusted p > 0.05) and consistency (Pearson's correlation coefficients >0.5) between two tissues, at each of the 767,412 CpGs, were evaluated. Results: We identified 247,721 CpGs showing overall agreement and 47,371 CpGs showing consistency in DNAm. Identified CpGs are involved in certain immune pathways, indicating the potential of using blood as a biomarker for BEC at those CpGs in lower airway-related diseases. Conclusion: CpGs showing overall agreement and those without overall agreement are distributed differently on the genome.

Fcγ Receptor IIa (FCGR2A) Polymorphism Is Associated With Severe Respiratory Syncytial Virus Disease in Argentinian Infants

Background

Most patients with respiratory syncytial virus (RSV) infection requiring hospitalization have no risk factors for severe disease. Genetic variation in the receptor for the Fc portion of IgG (FcγR) determines their affinity for IgG subclasses driving innate and adaptive antiviral immunity. We investigated the relationship between FcγRIIa-H131R polymorphism and RSV disease.

Methods

Blood samples were collected from 182 infants ≤24-month-old (50 uninfected, 114 RSV-infected with moderate course and 18 suffering severe disease). FcγRIIa-H131R SNP genotypic frequencies (HH, HR, RR) and anti-RSV IgG1, IgG2 and IgG3 levels were studied.

Results

Genotypic frequencies for FcγRIIa-H131R SNP were comparable between uninfected and RSV-infected infants. In contrast, we found a significant higher frequency of HH genotype in severe RSV-infected children compared to moderate patients. Among severe group, HH infants presented more factors associated to severity than HR or RR patients did. Furthermore, compared to moderate RSV-infected infants, severe patients showed higher levels of anti-RSV IgG1 and IgG3.

Conclusions

We found an association between an FcγRIIa (H131) polymorphism and severe RSV disease, which points towards a critical role for interactions between FcγRs and immune complexes in RSV pathogenesis. This genetic factor could also predict the worse outcome and identify those infants at risk during hospitalization.

IgE and IgG Antibodies as Regulators of Mast Cell and Basophil Functions in Food Allergy

Food allergy is a major health issue, affecting the lives of 8% of U.S. children and their families. There is an urgent need to identify the environmental and endogenous signals that induce and sustain allergic responses to ingested allergens. Acute reactions to foods are triggered by the activation of mast cells and basophils, both of which release inflammatory mediators that lead to a range of clinical manifestations, including gastrointestinal, cutaneous, and respiratory reactions as well as systemic anaphylaxis. Both of these innate effector cell types express the high affinity IgE receptor, FcϵRI, on their surface and are armed for adaptive antigen recognition by very-tightly bound IgE antibodies which, when cross-linked by polyvalent allergen, trigger degranulation. These cells also express inhibitory receptors, including the IgG Fc receptor, FcγRIIb, that suppress their IgE-mediated activation. Recent studies have shown that natural resolution of food allergies is associated with increasing food-specific IgG levels. Furthermore, oral immunotherapy, the sequential administration of incrementally increasing doses of food allergen, is accompanied by the strong induction of allergen-specific IgG antibodies in both human subjects and murine models. These can deliver inhibitory signals via FcγRIIb that block IgE-induced immediate food reactions. In addition to their role in mediating immediate hypersensitivity reactions, mast cells and basophils serve separate but critical functions as adjuvants for type 2 immunity in food allergy. Mast cells and basophils, activated by IgE, are key sources of IL-4 that tilts the immune balance away from tolerance and towards type 2 immunity by promoting the induction of Th2 cells along with the innate effectors of type 2 immunity, ILC2s, while suppressing the development of regulatory T cells and driving their subversion to a pathogenic pro-Th2 phenotype. This adjuvant effect of mast cells and basophils is suppressed when inhibitory signals are delivered by IgG antibodies signaling via FcγRIIb. This review summarizes current understanding of the immunoregulatory effects of mast cells and basophils and how these functions are modulated by IgE and IgG antibodies. Understanding these pathways could provide important insights into innovative strategies for preventing and/or reversing food allergy in patients.

IgE and mast cells: The endogenous adjuvant

Mast cells and IgE are most familiar as the effectors of type I hypersensitivity reactions including anaphylaxis. It is becoming clear however that this pair has important immunomodulatory effects on innate and adaptive cells of the immune system. In this purview, they act as endogenous adjuvants to ignite evolving immune responses, promote the transition of allergic disease into chronic illness and disrupt the development of active mechanisms of tolerance to ingested foods. Suppression of IgE-mediated mast cell activation can be exerted by molecules targeting IgE, FcɛRI or signaling kinases including Syk, or by IgG antibodies acting via inhibitory Fcγ receptors. In 2015 we reviewed the evidence for the adjuvant functions of mast cells. This update includes the original text, incorporates some important developments in the field over the past five years and discusses how interventions targeting these pathways might have promise in the development of strategies to treat allergic disease.

Immunological Role of IgG Subclasses

The loss of tolerance to self-antigens is the unequivocal "red line" of autoimmunity: both development of autoreactive T and B cells and production of polyclonal autoantibodies represent seminal keys to the pathogenesis of protean autoimmune diseases. Most of these autoantibodies are immunoglobulins G (IgG), functionally distinguished in four subclasses named IgG1, IgG2, IgG3, and IgG4, due to structural differences in the hinge and heavy chain constant regions. Different studies analyzed serum levels of IgG subclasses in the course of different disorders, showing that they might have a pathogenic role by regulating interactions among immunoglobulins, Fc-gamma receptors, and complement. To date, the mechanisms promoting different IgG subclasses distribution during the natural history of most autoimmune diseases remain somewhat unclear. Evidence from the medical literature shows that the serum IgG profile is peculiar for many autoimmune diseases, suggesting that different subclasses could be specific for the underlying driving autoantigens. A better knowledge of IgG subsets may probably help to elucidate their pathological task, but also to define their relevance for diagnostic purposes, patients' personalized management, and prognosis assessment.

Effects of intravenous immunoglobulin therapy and Fc gamma receptor polymorphisms on BK virus nephropathy in kidney transplant recipients

BACKGROUND

BK virus nephropathy (BKVN) is a major complication in kidney transplant patients. This study aimed to investigate the efficacy of intravenous immunoglobulin (IVIG) therapy against persistent BKVN and to evaluate the association between persistent BKVN and Fc gamma receptor (FcγR) single nucleotide polymorphisms (SNPs).

METHODS

A total of 86 patients out of 279 kidney recipients with BKVN were investigated in a single-center retrospective study. The majority of 86 patients were Hispanic and Asian (69.8% and 17.4%). Patients were treated with adjunctive IVIG or standard therapy (controls). Subgroup analysis was performed between IVIG responders and non-responders. BK virus copy number and serum creatinine (SCr) were measured to evaluate the impact of IVIG. We analyzed the association between the response to IVIG and genotype at FcγR3A (rs396991) and FcγR2A (rs1801274) SNPs.

RESULTS

Viral load in IVIG non-responders was significantly higher than in responders at the time of diagnosis (219 271.8 vs 29 816.3 copies/mL, P = .015) and after 6 months of IVIG use (12 789.5 vs 1369.5 copies/mL, P < .001). However, analyses SNP of FcγR2A (OR = 0.807, CI = 0.435-1.496 P = .495) and FcγR3A (OR = 0.997, CI = 0.505-1.970, P = .993) SNPs showed no significant differences between the 2 groups.

CONCLUSION

IVIG appears to lower BK DNA viral load significantly in patients with persistent BKVN. However, no associations were identified between BKVN and FcγR2A or FcγR3A SNPs.

Association between FCGR2A rs1801274 and MUC5B rs35705950 variations and pneumonia susceptibility

Background

Herein, we collected currently published data to comprehensively evaluate the impact of the FCGR2A (Fc fragment of IgG receptor IIa) rs1801274 and MUC5B (mucin 5B, oligomeric mucus/gel-forming) rs35705950 variations on susceptibility to pneumonia diseases.

Methods

We retrieved case-control studies from three online databases and applied the statistical approach of meta-analysis for a series of pooling analyses.

Results

A total of fourteen case-control studies were included for FCGR2A rs1801274; while thirty-one case-control studies were included for MUC5B rs35705950. No significant difference between pneumonia cases and controls for FCGR2A rs1801274 was found. However, MUC5B rs35705950 was significantly associated with pneumonia susceptibility in the whole population under the genetic models of allelic T vs. G [OR (odds ratio) =3.78], carrier T vs. G (OR = 3.31), TT vs. GG (OR = 13.66), GT vs. GG (OR = 4.78), GT + TT vs. GG (OR = 5.05), and TT vs. GG + GT (OR = 6.47) (all P < 0.001, Bonferroni-adjusted P < 0.006; false discovery rate-adjusted P < 0.0010). Furthermore, we observed a similar positive result for subgroup analyses of “Caucasian”, “Asian”, “population-based control”, and “idiopathic pulmonary fibrosis”.

Conclusions

MUC5B rs35705950, but not FCGR2A rs1801274, increases susceptibility to clinical pneumonia, especially to idiopathic pulmonary fibrosis, in both the Caucasian and Asian populations.

Understanding Fc Receptor Involvement in Inflammatory Diseases: From Mechanisms to New Therapeutic Tools

Fc receptors (FcRs) belong to the ITAM-associated receptor family. FcRs control the humoral and innate immunity which are essential for appropriate responses to infections and prevention of chronic inflammation or auto-immune diseases. Following their crosslinking by immune complexes, FcRs play various roles such as modulation of the immune response by released cytokines or of phagocytosis. Here, we review FcR involvement in pathologies leading notably to altered intracellular signaling with functionally relevant consequences to the host, and targeting of Fc receptors as therapeutic approaches. Special emphasis will be given to some FcRs, such as the FcαRI, the FcγRIIA and the FcγRIIIA, which behave like the ancient god Janus depending on the ITAM motif to inhibit or activate immune responses depending on their targeting by monomeric/dimeric immunoglobulins or by immune complexes. This ITAM duality has been recently defined as inhibitory or activating ITAM (ITAMi or ITAMa) which are controlled by Src family kinases. Involvement of various ITAM-bearing FcRs observed during infectious or autoimmune diseases is associated with allelic variants, changes in ligand binding ability responsible for host defense perturbation. During auto-immune diseases such as rheumatoid arthritis, lupus or immune thrombocytopenia, the autoantibodies and immune complexes lead to inflammation through FcR aggregation. We will discuss the role of FcRs in autoimmune diseases, and focus on novel approaches to target FcRs for resolution of antibody-mediated autoimmunity. We will finally also discuss the down-regulation of FcR functionality as a therapeutic approach for autoimmune diseases.

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.

Antibody Subclass Repertoire and Graft Outcome Following Solid Organ Transplantation

Long-term outcomes in solid organ transplantation are constrained by the development of donor-specific alloantibodies (DSA) against human leukocyte antigen (HLA) and other targets, which elicit antibody-mediated rejection (ABMR). However, antibody-mediated graft injury represents a broad continuum, from extensive complement activation and tissue damage compromising the function of the transplanted organ, to histological manifestations of endothelial cell injury and mononuclear cell infiltration but without concurrent allograft dysfunction. In addition, while transplant recipients with DSA as a whole fare worse than those without, a substantial minority of patients with DSA do not experience poorer graft outcome. Taken together, these observations suggest that not all DSA are equally pathogenic. Antibody effector functions are controlled by a number of factors, including antibody concentration, antigen availability, and antibody isotype/subclass. Antibody isotype is specified by many integrated signals, including the antigen itself as well as from antigen-presenting cells or helper T cells. To date, a number of studies have described the repertoire of IgG subclasses directed against HLA in pretransplant patients and evaluated the clinical impact of different DSA IgG subclasses on allograft outcome. This review will summarize what is known about the repertoire of antibodies to HLA and non-HLA targets in transplantation, focusing on the distribution of IgG subclasses, as well as the general biology, etiology, and mechanisms of injury of different humoral factors.

FCGR Polymorphisms Influence Response to IL2 in Metastatic Renal Cell Carcinoma

Purpose: Fc-gamma receptors (FCGRs) are expressed on immune cells, bind to antibodies, and trigger antibody-induced cell-mediated antitumor responses when tumor-reactive antibodies are present. The affinity of the FCGR/antibody interaction is variable and dependent upon FCGR polymorphisms. Prior studies of patients with cancer treated with immunotherapy indicate that FCGR polymorphisms can influence antitumor response for certain immunotherapies that act via therapeutically administered mAbs or via endogenous tumor-reactive antibodies induced from tumor antigen vaccines. The previously published "SELECT" trial of high-dose aldesleukin (HD-IL2) for metastatic renal cell carcinoma resulted in an objective response rate of 25%. We evaluated the patients in this SELECT trial to determine whether higher-affinity FCGR polymorphisms are associated with outcome.Experimental Design: SNPs in FCGR2A, FCGR3A, and FCGR2C were analyzed, individually and in combination, for associations between genotype and clinical outcome.Results: When higher-affinity genotypes for FCGR2A, FCGR3A, and FCGR2C were considered together, they were associated with significantly increased tumor shrinkage and prolonged survival in response to HD-IL2.Conclusions: Although associations of higher-affinity FCGR genotype with clinical outcome have been demonstrated with mAb therapy and with idiotype vaccines, to our knowledge, this is the first study to show associations of FCGR genotypes with outcome following HD-IL2 treatment. We hypothesize that endogenous antitumor antibodies may engage immune cells through their FCGRs, and HD-IL2 may enhance antibody-induced tumor destruction, or antibody-enhanced tumor antigen presentation, via augmented activation of innate or adaptive immune responses; this FCGR-mediated immune activity would be augmented through immunologically favorable FCGRs. Clin Cancer Res; 23(9); 2159-68. ©2016 AACR.

FcγRIIB and autoimmunity

Autoimmune diseases are characterized by adaptive immune responses against self-antigens, including humoral responses resulting in the production of autoantibodies. Autoantibodies generate inflammation by activating complement and engaging Fcγ receptors (FcγRs). The inhibitory receptor FcγRIIB plays a central role in regulating the generation of autoantibodies and their effector functions, which include activation of innate immune cells and the cellular arm of the adaptive immune system, via effects on antigen presentation to CD4 T cells. Polymorphisms in FcγRIIB have been associated with susceptibility to autoimmunity but protection against infections in humans and mice. In the last few years, new mechanisms by which FcγRIIB controls the adaptive immune response have been described. Notably, FcγRIIB has been shown to regulate germinal center B cells and dendritic cell migration, with potential impact on the development of autoimmune diseases. Recent work has also highlighted the implication of FcγRIIB on the regulation of the innate immune system, via inhibition of Toll-like receptor- and complement receptor-mediated activation. This review will provide an update on the role of FcγRIIB in adaptive immune responses in autoimmunity, and then focus on their emerging function in innate immunity.

Polymorphic Regions in Fc Gamma Receptor and Tumor Necrosis Factor-α Genes and Susceptibility to Chronic Periodontitis in a Cohort From South India

BACKGROUND

Polymorphisms in the immunoglobulin G Fc receptor II (FcGR) and tumor necrosis factor-α (TNFA) genes are known to influence pathogenesis and severity of several inflammatory conditions. Association of FcGR and TNFA gene polymorphisms with chronic periodontitis (CP) susceptibility has been found to be diverse among different ethnic populations. Objectives of the present study are to determine association of functional single nucleotide polymorphisms (SNPs) in FcGR and TNF-α genes with CP susceptibility in a cohort from South India.

METHODS

Polymorphisms of: 1) FCGR2A 131His/Arg (rs1801274); 2) FCGR2B 232Ile/Thr (rs1050501); 3) TNFA -1031T/C (rs1799964); and 4) TNFA -863C/A (rs1800630) were analyzed among patients with healthy gingiva (n = 176) and patients with CP (n = 177). Genotyping was performed using allele-specific real-time polymerase chain reaction assay. Association between CP and SNPs was examined by multivariable logistic regression analysis with adjustment for: 1) age; 2) sex; and 3) oral hygiene index (OHI). Epistatic interaction between FcGR polymorphisms and interleukin 1B (IL1B) +3954C/T (rs1143634) was assessed using multifactorial dimensionality reduction analysis.

RESULTS

Among four SNPs analyzed, only FCGR2A 131His/Arg showed significant association with CP in a dominant model (odds ratio: 1.6; 95% confidence interval: 1.028 to 2.530). This significance disappeared after correcting for multiple comparisons using Bonferroni analysis, or after adjusting for age, sex, and OHI. A significant redundant interaction between IL1B +3954 C/T and FCGR2A 131His/Arg was observed.

CONCLUSION

Study results suggest the variant form of the SNP in FCGR2A 131His/Arg, FCGR2B 232Ile/Thr, TNFA -1031T/C, and TNFA -863C/A are not associated with CP susceptibility in the selected cohort from South India.

Human FcR polymorphism and disease

Fc receptors play a central role in maintaining the homeostatic balance in the immune system. Our knowledge of the structure and function of these receptors and their naturally occurring polymorphisms, including single nucleotide polymorphisms and/or copy number variations, continues to expand. Through studies of their impact on human biology and clinical phenotype, the contributions of these variants to the pathogenesis, progression, and/or treatment outcome of many diseases that involve immunoglobulin have become evident. They affect susceptibility to bacterial and viral pathogens, constitute as risk factors for IgG or IgE mediated inflammatory diseases, and impact the development of many autoimmune conditions. In this chapter, we will provide an overview of these genetic variations in classical FcγRs, FcRLs, and other Fc receptors, as well as challenges in achieving an accurate and comprehensive understanding of the FcR polymorphisms and genomic architecture.