A genetic variant of immunoglobulin gamma2 is strongly associated with immunity to mucin 1 in patients with breast cancer

Impact of structural modifications of IgG antibodies on effector functions

Immunoglobulin G (IgG) antibodies are a critical component of the adaptive immune system, binding to and neutralizing pathogens and other foreign substances. Recent advances in molecular antibody biology and structural protein engineering enabled the modification of IgG antibodies to enhance their therapeutic potential. This review summarizes recent progress in both natural and engineered structural modifications of IgG antibodies, including allotypic variation, glycosylation, Fc engineering, and Fc gamma receptor binding optimization. We discuss the functional consequences of these modifications to highlight their potential for therapeutical applications.

Functional consequences of allotypic polymorphisms in human immunoglobulin G subclasses

Heritable polymorphisms within the human IgG locus, collectively termed allotypes, have often been linked by statistical associations, but rarely mechanistically, to a wide range of disease states. One potential explanation for these associations is that IgG allotype alters host cell receptors' affinity for IgG, dampening or enhancing an immune response depending on the nature of the change and the receptors. In this work, a panel of allotypic antibody variants were evaluated using multiplexed, label-free biophysical methods and cell-based functional assays to determine what effect, if any, human IgG polymorphisms have on antibody function. While we observed several differences in FcγR affinity among allotypes, there was little evidence of dramatically altered FcγR-based effector function or antigen recognition activity associated with this aspect of genetic variability.

circIGHG-Induced Epithelial-to-Mesenchymal Transition Promotes Oral Squamous Cell Carcinoma Progression via miR-142-5p/IGF2BP3 Signaling

Circular RNAs (circRNA) are a new member of endogenously produced noncoding RNAs that have been characterized as key regulators of gene expression in a variety of malignances. However, the role of circRNA in oral squamous cell carcinoma (OSCC) remains largely unknown. In this study, we identified unique circRNA that regulate OSCC progression and metastasis and pave roads for future research in early diagnosis, prevention, and treatment of OSCC. Transcriptomic analyses identified a circRNA derived from IGHG locus (circIGHG) as significantly upregulated in OSCC and positively associated with poor prognosis of OSCC. circIGHG directly bound miR-142-5p and consequently elevated IGF2BP3 activity. Knockdown of circIGHG led to impaired expression of IGF2BP3 and attenuated aggressiveness of OSCC cells. Epithelial-mesenchymal transition was the main mechanism through which circIGHG/IGF2BP3 promotes metastasis of OSCC. Overall, these results demonstrate that circIGHG plays a pivotal role in OSCC development and metastasis and has potential to serve as a biomarker and therapeutic target for early-stage diagnosis and treatment of OSCC. SIGNIFICANCE: These findings broaden our insights regarding regulation of OSCC progression by circular RNA and serve as a reference for future clinical research in OSCC diagnosis and treatment.

IGHG, IGKC, and FCGR genes and endogenous antibody responses to GARP in patients with breast cancer and matched controls

Glycoprotein-A repetitions predominant (GARP) is a transmembrane protein that is highly expressed in breast cancer. Its overexpression correlates with worse survival, and antibodies to GARP appear to play a protective role in a mouse model. No large-scale studies of immunity to GARP in humans have yet been undertaken. In this investigation, using a large multiethnic cohort (1738 subjects), we aimed to determine whether the magnitude of anti-GARP antibody responsiveness was significantly different in patients with breast cancer from that in matched healthy controls. We also investigated whether the allelic variation at the immunoglobulin GM (γ marker), KM (κ marker), and Fcγ receptor (FcγR) loci contributed to the interindividual variability in anti-GARP IgG antibody levels. A combined analysis of all subjects showed that levels of anti-GARP antibodies were significantly higher in patients with breast cancer than in healthy controls (mean ± SD: 7.4 ± 3.5 vs. 6.9 ± 3.5 absorbance units per mL (AU/μL), p < 0.0001). In the two populations with the largest sample size, the probability of breast cancer generally increases as anti-GARP antibody levels increase. Several significant individual and epistatic effects of GM, KM, and FcγR genotypes on anti-GARP antibody responsiveness were noted in both patients and controls. These results, if confirmed by independent investigations, will aid in devising personalized GARP-based immunotherapeutic strategies against breast cancer and other GARP-overexpressing malignancies.

Endogenous antibody responses to mucin 1 in a large multiethnic cohort of patients with breast cancer and healthy controls: Role of immunoglobulin and Fcγ receptor genes

High levels of naturally occurring IgG antibodies to mucin 1 (MUC1), a membrane-bound glycoprotein that is overexpressed in patients with breast cancer, are associated with good prognosis. This suggests that endogenous anti-MUC1 antibodies have a protective effect and, through antibody-mediated host immunosurveillance mechanisms, might contribute to a cancer-free state. To test this possibility, we characterized a large number of multiethnic patients with breast cancer and matched controls for IgG antibodies to MUC1. We also aimed to determine whether the magnitude of anti-MUC1 antibody responsiveness was associated with particular immunoglobulin GM (γ marker), KM (κ marker), and Fcγ receptors (FcγR) genotypes. After adjusting for the confounding variables in a multivariate analysis, we found no significant difference in the levels of anti-MUC1 IgG antibodies between patients and cancer-free controls. However, in patients and controls, particular GM, KM, and FcγR genotypes-individually or epistatically-were significantly associated with the levels of anti-MUC1 IgG antibodies in a racially restricted manner. These findings, if confirmed in an independent investigation, could help identify individuals most likely to benefit from a MUC1-based therapeutic or prophylactic vaccine for MUC1-overexpressing malignancies.

Mucin 1-specific B cell immune responses and their impact on overall survival in breast cancer patients

Considering the diverse functions of B cells, responses to tumor-associated antigens (TAA) have been thought to be the main source of B cell-mediated antitumor immunity. Polymorphic epithelial mucin (MUC1) is considered one of the most specific TAA in patients with breast cancer. The present study aims to dissect the level and subclasses of naturally occurring anti-MUC1 antibodies in regard to tumor biologic parameters, clinical characteristics and overall survival. In 288 primary, non-metastatic breast cancer patients, pretreatment serum levels of anti-MUC1 immunoglobulin G (IgG) and its subclasses G1-4 as well as immunoglobulin M (IgM) were analyzed via ELISA. With respect to overall survival (Kaplan-Meier analysis), tumor biologic parameters as hormone receptor status, human epidermal growth factor receptor 2 (Her2), Ki-67 expression and tumor grading have been correlated as well as clinical characteristics as nodal involvement, tumor stage and patients' age at the time of diagnosis. Median follow-up time was 148 mo (IQR: 73.1-158.5 mo). A significant increase in IgG antibody titers was correlated highly significantly with an improved overall survival of patients. In multivariate analysis, total IgG proved to be an independent prognostic marker for overall survival (p = 0.002). IgG subclass analysis did not reveal any correlation of IgG1, IgG3 and IgG4 levels with overall survival, while increased immunoglobulin G2 (IgG2) values, although statistically not significant, tended to correlate with prolonged patient survival. MUC1-specific IgM antibodies were shown not to be predictive of overall survival. Altogether, humoral immune responses appear to play a crucial part in the tumor immunity of breast cancer patients. The present data confirms the positive impact of tumor-specific IgG on prolonged overall survival in breast cancer patients. MUC1-antibody testing might be a useful tool to identify high-risk patients who may need adjuvant therapy and potentially might benefit from MUC1-directed immunotherapy.

Innate IgG molecules and innate B cells expressed by immunoglobulin constant heavy G chain (Fcγ) genetic marker genes are involved in the 'allergic march' of IgE sensitization in children

BACKGROUND

Interindividual variations of immunoglobulin constant heavy G chain (IGHG) genes on chromosome 14q32.3 are identified by alternative genetic markers (GM) of IgG3, IgG1 and IgG2, respectively. They express structurally and functionally innate IgG molecules and B cells, associated with allergic disease, replicated in several studies.

MATERIALS AND METHODS

1-year-old and 10-year-old, IgE-sensitized and non-sensitized children from the German Multicenter Allergy Study birth cohort were assessed by new serological methods for the mendelian IGHG (Fcγ) (GM) genes, as innate IgG molecules and innate B cells.

RESULTS

Food allergy sensitization in thirty-five 1-year-old children (124 not sensitized) was associated with the IGHG*bfn haplotype and B*(bfn) cells (OR 1.9, 95% CI 1.2-3.1; p = 0.010). Aeroallergen sensitization in ninety-nine 10-year-old children (95 not sensitized) was associated with the same genes (OR 1.4, 95% CI 1.02-1.9; p = 0.034). The IgE sensitization was most prominent in the restrictive homozygous IGHG*bfn/*bfn diplotype, 34% at age 1, increasing to 60% at age 10, rating the highest numbers of positive IgE tests, expressing increased levels of IgE and innate IgG2*n.

CONCLUSIONS

The IGHG*bfn haplotype (B*(bfn) cells) and increased innate IgG2*n levels are predictive factors for IgE sensitization in childhood. IGHG genes can be assessed for prognostic and preventive purposes in clinical care.

Endogenous antibody responsiveness to epidermal growth factor receptor is associated with immunoglobulin allotypes and overall survival of patients with glioblastoma

BACKGROUND

Immunoglobulin γ marker (GM) and κ marker (KM) allotypes, hereditary antigenic determinants of γ and κ chains, respectively, have been shown to be associated with immunity to a variety of self and nonself antigens, but their possible contribution to immunity to the tumor-associated antigens epidermal growth factor receptor (EGFR) and EGFR variant (v)III has not been evaluated. The aim of the present investigation was to determine whether the interindividual variation in endogenous antibody responsiveness to EGFR and EGFRvIII is associated with particular GM, KM, and Fcγ receptor (FcγR) genotypes and whether antibody levels were associated with the overall survival of patients with glioblastoma.

METHODS

A total of 126 Caucasian participants with glioblastoma were genotyped for several GM, KM, and FcγR alleles and characterized for IgG antibodies to EGFR and EGFRvIII antigens.

RESULTS

The anti-EGFR antibody levels associated with GM 3/3 homozygotes and GM 3/17 heterozygotes were similar (15.9 vs 16.4 arbitrary units [AU]/µL) and significantly lower than those associated with GM 17/17 homozygotes (19.6 AU/µL; nominal P = .007). Participants homozygous for the GM 21 allele also had significantly higher levels of anti-EGFR antibodies than GM 5/5 homozygotes and GM 5/21 heterozygotes (20.1 vs 16.0 and 16.3 AU/µL; nominal P = .005). Similar associations were found with immune responsiveness to EGFRvIII. Higher anti-EGFR and anti-EGFRvIII antibody levels were associated with enhanced overall survival (16 vs 11 mo, nominal P = .038 and 20 vs 11 mo, nominal P = .004, respectively).

CONCLUSIONS

GM allotypes contribute to humoral immunity to EGFR in glioblastoma.

Immunoglobulin GM Genes, Cytomegalovirus Immunoevasion, and the Risk of Glioma, Neuroblastoma, and Breast Cancer

Human cytomegalovirus (HCMV), a common herpes virus, has been reported to be a risk factor for many diseases, including malignant diseases such as glioma, neuroblastoma, and breast cancer. Some of the HCMV-associated diseases (e.g., glioma) are rare. The question arises: how could a common virus be associated with uncommon diseases? Interactions between a major gene complex of the human immune system and a viral immunoevasion strategy – a probable mechanism of their co-evolutionary adaptation – may shed light on this paradox. To ensure its survival, HCMV has evolved sophisticated immunoevasion strategies. One strategy involves encoding decoy Fcγ receptors (FcγR), which may enable the virus to evade host immunosurveillance by avoiding the Fcγ-mediated effector consequences of anti-HCMV IgG antibody binding. Immunoglobulin G1 proteins expressing GM (γ marker) alleles 3 and 17 have differential affinity to the HCMV TRL11/IRL11-encoded FcγR, and thus act as effect modifiers of HCMV-associated malignancies. The high affinity GM 3 allele has been shown to be a risk factor for neuroblastoma, glioma, and breast cancer. Additional studies involving other viral FcγRs as well as GM alleles expressed on other IgG subclasses are warranted.

Genetic variants of immunoglobulin γ and κ chains influence humoral immunity to the cancer-testis antigen XAGE-1b (GAGED2a) in patients with non-small cell lung cancer

GM (γ marker) allotypes, genetic variants of immunoglobulin γ chains, have been reported to be associated strongly with susceptibility to lung cancer, but the mechanism(s) underlying this association is not known. One mechanism could involve their contribution to humoral immunity to lung tumour-associated antigens. In this study, we aimed to determine whether particular GM and KM (κ marker) allotypes were associated with antibody responsiveness to XAGE-1b, a highly immunogenic lung tumour-associated cancer-testis antigen. Sera from 89 patients with non-small cell lung cancer (NSCLC) were allotyped for eight GM and two KM determinants and characterized for antibodies to a synthetic XAGE-1b protein. The distribution of various GM phenotypes was significantly different between XAGE-1b antibody-positive and -negative patients (P = 0·023), as well as in the subgroup of XAGE-1b antigen-positive advanced NSCLC (P = 0·007). None of the patients with the GM 1,17 21 phenotype was positive for the XAGE-1b antibody. In patients with antigen-positive advanced disease, the prevalence of GM 1,2,17 21 was significantly higher in the antibody-positive group than in those who lacked the XAGE-1b antibody (P = 0·026). This phenotype also interacted with a particular KM phenotype: subjects with GM 1,2,17 21 and KM 3,3 phenotypes were almost four times (odds ratio = 3·8) as likely to be positive for the XAGE-1b antibody as the subjects who lacked these phenotypes. This is the first report presenting evidence for the involvement of immunoglobulin allotypes in immunity to a cancer-testis antigen, which has important implications for XAGE-1b-based immunotherapeutic interventions in lung adenocarcinoma.

Human immunoglobulin constant heavy G chain (IGHG) (Fcγ) (GM) genes, defining innate variants of IgG molecules and B cells, have impact on disease and therapy

The distinguished alternative GM allotypes localized in immunoglobulin constant heavy G chain IGHG (Fcγ) (GM) genes on chromosome 14q32.3 define two unique variants of respectively IgG3, IgG1 and IgG2 subclasses, with different structures and functions. The IGHG allele (allotypes), expressed in homozygous or heterozygous forms, are assessed by new serological methods. Fixed combinations of γ3, γ1 and γ2 allotypes constitute the haplotypes, which are indirect markers of B cells. We highlight the role of homozygous IGHG genes with restricted qualities of IgG subclass molecules and B cells. These common Mendelian IGHG genes respond differently to allergens and infections, both bacterial and viral, and to active and passive immunotherapies. IGHG genes have an impact on diseases such as allergy, immunodeficiency, autoimmunity and malignancy. Association/linkage of different IGHG genes gives information about risk/protection, good or bad prognosis, for improvement of clinical care. The IGHG gene map of healthy Caucasians is registered.

The forgotten tale of immunoglobulin allotypes in cancer risk and treatment

Monoclonal antibody (mAb) has fulfilled the promise of being the "Magic Bullet" in oncology with the clinical success of mAbs against CD20, Her-2/neu, epidermal growth factor receptor, vascular endothelial cell growth factor and others in a variety of cancers. Most manufacturers of mouse-human chimeric antibodies (and most immunologists) have treated the constant region of human immunoglobulin (Ig) as if it were naturally monomorphic and therefore not immunogenic in humans. In fact, the constant region of Ig heavy and light chain is highly polymorphic, and yet Ig haplotypes are usually not defined by genome-wide association studies nor are they considered to be important for optimizing mAb therapy. We hereby summarize evidence that Ig allotypes are important and biologically relevant in that they contribute to the etiopathogenesis of many malignant, infectious, and autoimmune diseases. Because Ig allotypes differ from each other in engaging Fc receptor, we argue that future development of effective mAb therapy for cancer should take a patient-specific approach by using the correct allotype for each patient to maximize the efficacy of this therapy.

A genetic variant of FcγRIIIa is strongly associatedwith humoral immunity to cyclin B1 in African American patients with prostate cancer

There are significant inter-individual differences in naturally occurring antibody responses to the tumor-associated antigen cyclin B1 in healthy subjects with no history of cancer as well as in patients with multiple types of cancer, but the host genetic factors that might contribute to these differences have not been identified. The aim of the present investigation was to determine whether the variation in endogenous antibody levels to cyclin B1 in patients with prostate cancer was associated with immunoglobulin GM and KM alleles, expressed on the constant regions of γ and κ chains, respectively. We also aimed to determine whether particular Fcgamma receptor (FcγR) genotypes, which have been implicated in the immunobiology of several cancers, contribute to the magnitude of humoral immunity to cyclin B1. DNA samples from 129 Caucasian American (CA) and 76 African American (AA) patients with prostate cancer were genotyped for several GM, KM, and FcγR alleles. Plasma samples from these subjects were also characterized for IgG antibodies to cyclin B1. No significant associations were found between any genetic markers and the level of anticyclin B1 antibodies in CA patients. In AA patients, however, homozygosity for the valine allele at the FcγRIIIa locus was strongly associated with low antibody responsiveness to cyclin B1 (p = 0.0007). Since immunity to cyclin B1 has been shown to play a protective role, these results may, at least in part, explain the disproportionately higher rate of mortality in AA patients with prostate cancer.

Natural and Induced Humoral Responses to MUC1

MUC1 is a membrane-tethered mucin expressed on the ductal cell surface of glandular epithelial cells. Loss of polarization, overexpression and aberrant glycosylation of MUC1 in mucosal inflammation and in adenocarcinomas induces humoral immune responses to the mucin. MUC1 IgG responses have been associated with a benefit in survival in patients with breast, lung, pancreatic, ovarian and gastric carcinomas. Antibodies bound to the mucin may curb tumor progression by restoring cell-cell interactions altered by tumor-associated MUC1, thus preventing metastatic dissemination, as well as counteracting the immune suppression exerted by the molecule. Furthermore, anti-MUC1 antibodies are capable of effecting tumor cell killing by antibody-dependent cell-mediated cytotoxicity. Although cytotoxic T cells are indispensable to achieve anti-tumor responses in advanced disease, abs to tumor-associated antigens are ideally suited to address minimal residual disease and may be sufficient to exert adequate immune surveillance in an adjuvant setting, destroying tumor cells as they arise or maintaining occult disease in an equilibrium state. Initial evaluation of MUC1 peptide/glycopeptide mono and polyvalent vaccines has shown them to be immunogenic and safe; anti-tumor responses are scarce. Progress in carbohydrate synthesis has yielded a number of sophisticated substrates that include MUC1 glycopeptide epitopes that are at present in preclinical testing. Adjuvant vaccination with MUC1 glycopeptide polyvalent vaccines that induce strong humoral responses may prevent recurrence of disease in patients with early stage carcinomas. Furthermore, prophylactic immunotherapy targeting MUC1 may be a strategy to strengthen immune surveillance and prevent disease in subjects at hereditary high risk of breast, ovarian and colon cancer.

Genetic regulation of antibody responses to human epidermal growth factor receptor 2 in breast cancer

Host genetic factors responsible for the interindividual differences in naturally occurring antibody responses to the human epidermal growth factor receptor 2 (HER-2) in human beings have not been identified. The aim of the present investigation was to determine whether immunoglobulin gamma heavy-chain marker (GM) and kappa light-chain marker (KM) allotypes, which are genetic markers of IgG heavy chains and κ-type light chains, respectively, contribute to these differences. A total of 152 Estonian women with breast cancer were characterized for IgG antibodies to HER-2 and allotyped for several GM and KM markers. IgG3 determinant GM 13 was significantly associated with higher HER-2 IgG levels (median IgG titer 800 vs 400, p = 0.007). Other GM allotypes, known to be in linkage disequilibrium with GM 13, were also associated with higher anti-HER-2 antibody levels, albeit not as strongly. These results show that GM allotypes are associated with humoral immunity to HER-2, a finding with potentially significant implications for immunotherapy of breast cancer.

Human immunoglobulin allotypes: possible implications for immunogenicity

More than twenty recombinant monoclonal antibodies are approved as therapeutics. Almost all of these are based on the whole IgG isotype format, but vary in the origin of the variable regions between mouse (chimeric), humanized mouse and fully human sequences; all of those with whole IgG format employ human constant region sequences. Currently, the opposing merits of the four IgG subclasses are considered with respect to the in vivo biological activities considered to be appropriate to the disease indication being treated. Human heavy chain genes also exhibit extensive structural polymorphism(s) and, being closely linked, are inherited as a haplotype. Polymorphisms (allotypes) within the IgG isotype were originally discovered and described using serological reagents derived from humans; demonstrating that allotypic variants can be immunogenic and provoke antibody responses as a result of allo-immunization. The serologically defined allotypes differ widely within and between population groups; therefore, a mAb of a given allotype will, inevitably, be delivered to a cohort of patients homozygous for the alternative allotype. This publication reviews the serologically defined human IgG allotypes and considers the potential for allotype differences to contribute to or potentiate immunogenicity.