Genetic and Functional Profiling of CD16-Dependent Natural Killer Activation Identifies Patients at Higher Risk of Cardiac Allograft Vasculopathy

MICB Genomic Variant Is Associated with NKG2D-mediated Acute Lung Injury and Death

Rationale: Acute lung injury (ALI) carries a high risk of mortality but has no established pharmacologic therapy. We previously found that experimental ALI occurs through natural killer (NK) cell NKG2D receptor activation and that the cognate human ligand, MICB, was associated with ALI after transplantation. Objectives: To investigate the association of a common missense variant, MICBG406A, with ALI. Methods: We assessed MICBG406A genotypes within two multicenter observational study cohorts at risk for ALI: primary graft dysfunction (N = 619) and acute respiratory distress syndrome (N = 1,376). Variant protein functional effects were determined in cultured and ex vivo human samples. Measurements and Main Results: Recipients of MICBG406A-homozygous allografts had an 11.1% absolute risk reduction (95% confidence interval [CI], 3.2-19.4%) for severe primary graft dysfunction after lung transplantation and reduced risk for allograft failure (hazard ratio, 0.36; 95% CI, 0.13-0.98). In participants with sepsis, we observed 39% reduced odds of moderately or severely impaired oxygenation among MICBG406A-homozygous individuals (95% CI, 0.43-0.86). BAL NK cells were less frequent and less mature in participants with MICBG406A. Expression of missense variant protein MICBD136N in cultured cells resulted in reduced surface MICB and reduced NKG2D ligation relative to wild-type MICB. Coculture of variant MICBD136N cells with NK cells resulted in less NKG2D activation and less susceptibility to NK cell killing relative to the wild-type cells. Conclusions: These data support a role for MICB signaling through the NKG2D receptor in mediating ALI, suggesting a novel therapeutic approach.

Impact of SARS-CoV-2 vaccination on FcγRIIIA/CD16 dynamics in Natural Killer cells: relevance for antibody-dependent functions

Introduction

Natural Killer (NK) cells contribute to the protective effects of vaccine-induced antibodies thanks to the low affinity receptor for IgG, FcγRIIIA/CD16, whose aggregation leads to the killing of infected cells and IFNγ release, through which they potentiate adaptive immune responses.

Methods

Forty-seven healthy young individuals undergoing either homologous (ChAdOx1-S/ChAdOx1-S) or heterologous (ChAdOx1-S/BNT162B2) SARS-CoV-2 vaccination settings were recruited. Peripheral blood samples were collected immediately prior to vaccination and 8 weeks after the booster dose. The phenotypic and functional profile of NK cells was evaluated by flow cytometry at both time points. Serum samples were tested to evaluate circulating anti-Spike IgG levels and cytomegalovirus serostatus. CD16 F158V polymorphism was assessed by sequencing analysis.

Results

The downregulation of CD16 and the selective impairment of antibody-dependent cytotoxicity and IFNγ production in CD56dim NK population, persisting 8 weeks after boosting, were observed in heterologous, but not in homologous SARS-CoV-2 vaccination scheme. While the magnitude of CD16-dependent functions of the global CD56dim pool correlated with receptor levels before and after vaccination, the responsivity of NKG2C+ subset, that displays amplified size and functionality in HCMV+ individuals, resulted intrinsically insensitive to CD16 levels. Individual CD16 responsiveness was also affected by CD16F158V polymorphism; F/F low affinity individuals, characterized by reduced CD16 levels and functions independently of vaccination, did not show post-vaccinal functional impairment with respect to intermediate and high affinity ones, despite a comparable CD16 downregulation. Further, CD16 high affinity ligation conditions by means of afucosylated mAb overcame vaccine-induced and genotype-dependent functional defects. Finally, the preservation of CD16 expression directly correlated with anti-Spike IgG titer, hinting that the individual magnitude of receptor-dependent functions may contribute to the amplification of the vaccinal response.

Conclusion

This study demonstrates a durable downmodulation of CD16 levels and Ab-dependent NK functions after SARS-CoV-2 heterologous vaccination, and highlights the impact of genetic and environmental host-related factors in modulating NK cell susceptibility to post-vaccinal Fc-dependent functional impairment.

The Transplant Bellwether: Endothelial Cells in Antibody-Mediated Rejection

Ab-mediated rejection of organ transplants remains a stubborn, frequent problem affecting patient quality of life, graft function, and grant survival, and for which few efficacious therapies currently exist. Although the field has gained considerable knowledge over the last two decades on how anti-HLA Abs cause acute tissue injury and promote inflammation, there has been a gap in linking these effects with the chronic inflammation, vascular remodeling, and persistent alloimmunity that leads to deterioration of graft function over the long term. This review will discuss new data emerging over the last 5 y that provide clues into how ongoing Ab-endothelial cell interactions may shape vascular fate and propagate alloimmunity in organ transplants.

Protective and pathogenic functions of innate lymphoid cells in transplantation

Innate lymphoid cells (ILCs) are a family of lymphocytes with essential roles in tissue homeostasis and immunity. Along with other tissue-resident immune populations, distinct subsets of ILCs have important roles in either promoting or inhibiting immune tolerance in a variety of contexts, including cancer and autoimmunity. In solid organ and hematopoietic stem cell transplantation, both donor and recipient-derived ILCs could contribute to immune tolerance or rejection, yet understanding of protective or pathogenic functions are only beginning to emerge. In addition to roles in directing or regulating immune responses, ILCs interface with parenchymal cells to support tissue homeostasis and even regeneration. Whether specific ILCs are tissue-protective or enhance ischemia reperfusion injury or fibrosis is of particular interest to the field of transplantation, beyond any roles in limiting or promoting allograft rejection or graft-versus host disease. Within this review, we discuss the current understanding of ILCs functions in promoting immune tolerance and tissue repair at homeostasis and in the context of transplantation and highlight where targeting or harnessing ILCs could have applications in novel transplant therapies.

Bioinformatics and systems biology approaches to identify molecular targeting mechanism influenced by COVID-19 on heart failure

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as a contemporary hazard to people. It has been known that COVID-19 can both induce heart failure (HF) and raise the risk of patient mortality. However, the mechanism underlying the association between COVID-19 and HF remains unclear. The common molecular pathways between COVID-19 and HF were identified using bioinformatic and systems biology techniques. Transcriptome analysis was performed to identify differentially expressed genes (DEGs). To identify gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways, common DEGs were used for enrichment analysis. The results showed that COVID-19 and HF have several common immune mechanisms, including differentiation of T helper (Th) 1, Th 2, Th 17 cells; activation of lymphocytes; and binding of major histocompatibility complex class I and II protein complexes. Furthermore, a protein-protein interaction network was constructed to identify hub genes, and immune cell infiltration analysis was performed. Six hub genes (FCGR3A, CD69, IFNG, CCR7, CCL5, and CCL4) were closely associated with COVID-19 and HF. These targets were associated with immune cells (central memory CD8 T cells, T follicular helper cells, regulatory T cells, myeloid-derived suppressor cells, plasmacytoid dendritic cells, macrophages, eosinophils, and neutrophils). Additionally, transcription factors, microRNAs, drugs, and chemicals that are closely associated with COVID-19 and HF were identified through the interaction network.

The Role of Fc Gamma Receptors in Antibody-Mediated Rejection of Kidney Transplants

For the past decades, complement activation and complement-mediated destruction of allograft cells were considered to play a central role in anti-HLA antibody-mediated rejection (AMR) of kidney transplants. However, also complement-independent mechanisms are relevant in the downstream immune activation induced by donor-specific antibodies, such as Fc-gamma receptor (FcγR)-mediated direct cellular activation. This article reviews the literature regarding FcγR involvement in AMR, and the potential contribution of FcγR gene polymorphisms to the risk for antibody mediated rejection of kidney transplants. There is large heterogeneity between the studies, both in the definition of the clinical phenotypes and in the technical aspects. The study populations were generally quite small, except for two larger study cohorts, which obviates drawing firm conclusions regarding the associations between AMR and specific FcγR polymorphisms. Although FcγR are central in the pathophysiology of AMR, it remains difficult to identify genetic risk factors for AMR in the recipient’s genome, independent of clinical risk factors, independent of the donor-recipient genetic mismatch, and in the presence of powerful immunosuppressive agents. There is a need for larger, multi-center studies with standardised methods and endpoints to identify potentially relevant FcγR gene polymorphisms that represent an increased risk for AMR after kidney transplantation.

FCGR2A-HH Gene Variants Encoding the Fc Gamma Receptor for the C-Reactive Protein Are Associated with Enhanced Monocyte CD32 Expression and Cardiovascular Events’ Recurrence after Primary Acute Coronary Syndrome

Fcγ receptors (FcγRs) interact with the C-reactive protein (CRP) and mediate activation of inflammation-related pathogenic mechanisms affecting cardiovascular health. Our study evaluated whether FcγRIIA and FcγRIIIA profiles are associated with the recurrence of adverse cardiovascular events during the first year after a primary acute coronary syndrome (ACS). The primary endpoint was the recurrence of cardiovascular events (RCE), identified as a composite outcome comprising acute heart failure (AHF) and major adverse cardiovascular events (MACE). We obtained blood samples of 145 ACS patients to measure hsCRP circulating levels, to identify FcγRIIA-131RH rs1801274 and FcγRIIIA-158FV rs396991 polymorphisms, to analyze circulating monocytes and NK cell subsets expressing CD16 and CD32, and to detect serum-mediated FCGR2A-HH activation by luciferase reporter assays. The hsCRP, CD32-expression, and Fc-R mediated activation levels were similar in all patients regardless of their MACE risk. In contrast, the hsCRP levels and the proportion of CD14+ circulating monocytes expressing the CD32 receptor for CRP were significantly higher in the patients who developed AHF. The FCGR2A rs1801274 HH genotype was significantly more common in patients who developed RCE and MACE than in RCE-free patients and associated with an enhanced percentage of circulating CD32+CD14+ monocytes. The FCGR2A-HH genotype was identified as an independent predictor of subsequent RCE (OR, 2.7; p = 0.048; CI, 1.01–7.44) by multivariate analysis. These findings bring preliminary evidence that host FCGR2A genetic variants can influence monocyte CD32 receptor expression and may contribute to the fine-tuning of CD32-driven chronic activating signals that affect the risk of developing RCEs following primary ACS events.

Cellular and Molecular Crosstalk of Graft Endothelial Cells During AMR: Effector Functions and Mechanisms

Graft endothelial cell (EC) injury is central to the pathogenesis of antibody-mediated rejection (AMR). The ability of donor-specific antibodies (DSA) to bind C1q and activate the classical complement pathway is an efficient predictor of graft rejection highlighting complement-dependent cytotoxicity as a key process operating during AMR. In the past 5 y, clinical studies further established the cellular and molecular signatures of AMR revealing the key contribution of other, IgG-dependent and -independent, effector mechanisms mediated by infiltrating NK cells and macrophages. Beyond binding to alloantigens, DSA IgG can activate NK cells and mediate antibody-dependent cell cytotoxicity through interacting with Fcγ receptors (FcγRs) such as FcγRIIIa (CD16a). FcRn, a nonconventional FcγR that allows IgG recycling, is highly expressed on ECs and may contribute to the long-term persistence of DSA in blood. Activation of NK cells and macrophages results in the production of proinflammatory cytokines such as TNF and IFNγ that induce transient and reversible changes in the EC phenotype and functions promoting coagulation, inflammation, vascular permeability, leukocyte trafficking. MHC class I mismatch between transplant donor and recipient can create a situation of "missing self" allowing NK cells to kill graft ECs. Depending on the microenvironment, cellular proximity with ECs may participate in macrophage polarization toward an M1 proinflammatory or an M2 phenotype favoring inflammation or vascular repair. Monocytes/macrophages participate in the loss of endothelial specificity in the process of endothelial-to-mesenchymal transition involved in renal and cardiac fibrosis and AMR and may differentiate into ECs enabling vessel and graft (re)-endothelialization.

Cardiac allograft vasculopathy after heart transplantation: Pathophysiology, detection approaches, prevention, and treatment management

Cardiac allograft vasculopathy (CAV) continues to be a significant risk factor for the recipient's long-term survival following heart transplantation. Our knowledge of its etiology is constantly changing as new imaging techniques provide direct insight into the disease's natural history. CAV identification continues to be difficult since symptoms may be varied or nonexistent. Due to the irreversible nature of the disease, early diagnosis is critical to halting development. Prognostic tools and biomarkers have proliferated as a result of advancements in diagnostic techniques. Simultaneously, pharmaceutical advancements have aided in the amelioration of the disease's progressive progression.

Impacts of single nucleotide polymorphisms in Fc gamma receptor IIA (rs1801274) on lung transplant outcomes among Japanese lung transplant recipients

This study aimed to analyze the influences of single nucleotide polymorphisms (SNPs) in Fc gamma receptor IIA (FCGR2A) on postoperative outcomes after lung transplantation (LTx). We enrolled 191 lung transplant recipients (80 undergoing living-donor lobar lung transplants [LDLLTs] and 111 undergoing deceased-donor lung transplants [DDLTs]) in this study. We identified SNPs in FCGR2A (131 histidine [H] or arginine [R]; rs1801274) and reviewed the infectious complication-free survival after ICU discharge. The SNPs in FCGR2A comprised H/H (n=53), H/R (n=24), and R/R (n=3) in LDLLT, and H/H (n=67), H/R (n=42), and R/R (n=2) in DDLT. Recipients with H/H (H/H group) and those with H/R or R/R (R group) were compared in the analyses of infectious complications. In multivariate analyses, the R group of SNPs in FCGR2A was associated with pneumonia-free survival (HR: 2.52 [95% confidence interval {CI}: 1.35-4.71], p=0.004), fungal infection-free survival (HR: 2.50 [95% CI: 1.07-5.84], p=0.035), and cytomegalovirus infection-free survival (HR: 2.24 [95% CI: 1.07-4.69], p=0.032) in LDLLT but it was not associated with infectious complication-free survival in DDLT. Therefore, in LDLLT, more attention to infectious complications might need to be paid for LTx recipients with H/R or R/R than for those with H/H.

The FCGR3A 158 V/V-genotype is associated with decreased survival of renal allografts with chronic active antibody-mediated rejection

Natural killer (NK) cells express the Fc-gamma receptor CD16 (FCGR3A) and could therefore mediate renal endothelial cell damage in cases of chronic-active antibody mediated rejection (c-aABMR). The V/V-genotype of the FCGR3A 158 F/V polymorphism is associated with increased CD16 expression and cytotoxicity by NK cells. This study evaluated whether this genotype is associated with the diagnosis of c-aABMR and renal allograft loss. The distribution of the FGCR3A 158 F/V-genotypes was not different for c-aABMR cases (N = 133) compared to control kidney transplant recipients (N = 116, P = 0.65). The V-allele was associated with increased median fluorescence intensity (MFI) of CD16 by NK cells (MFI 3.5 × 10⁴ versus 1.3 × 10⁴ for V/V and F/F-genotype, P < 0.001). Increased expression of CD16 correlated with CD16-dependent degranulation of NK cells (R = 0.4; P = 0.02). Moreover, the V/V-genotype was significantly associated with a higher glomerulitis score and an independent risk factor (HR 1.98; P = 0.04) for decreased allograft survival. Death-censored graft survival in c-aABMR cases at 3 years follow-up was 33% for the FCGR3A 158 V/V-genotype versus 62% for the F/F-genotype. In conclusion, the FCGR3A V/V-genotype increases CD16-mediated NK cell cytotoxicity and is associated with a higher glomerulitis score and decreased graft survival in cases with c-aABMR.

NK cells in antibody-mediated rejection - Key effector cells in microvascular graft damage

Antibody-mediated rejection (ABMR) stands as the major limitation to long-term transplant outcome. The immunologic understanding of ABMR continues to progress and has identified natural killer (NK) cells as key effector cells promoting and coordinating the immune attack on the graft microvascular endothelium. This review discusses the current concepts outlining the different ways that allow for NK cell recognition of graft endothelial cells which includes antibody-dependent as well as independent processes.

Dinutuximab Synergistically Enhances the Cytotoxicity of Natural Killer Cells to Retinoblastoma Through the Perforin-Granzyme B Pathway

Purpose

Conventional chemotherapy and enucleation usually fail to cure advanced retinoblastoma. We investigated the retinoblastoma immune microenvironment and the efficacy of the combination of dinutuximab and CD16-expressing NK-92MI (NK-92MI^hCD16-GFP) cells on retinoblastoma cells in this study.

Patients and Methods

Immunohistochemistry and flow cytometry (FC) were performed to assess the expression level of GD2 in retinoblastoma tissues and cells. Gene set enrichment analysis (GSEA), immunohistochemisrztry and immunocytochemistry were conducted to assess the retinoblastoma immune microenvironment and the integrity of the blood-retinal barrier (BRB). After overexpressing CD16 in NK-92MI cells, fluorescence-activated cell sorting (FACS) was applied to select the positive subpopulation. LDH assays and FC were used to detect LDH release and apoptosis in retinoblastoma cells subjected to a combination of dinutuximab and NK-92MI^hCD16-GFP cells. Finally, the release of perforin-granzyme B and the expression of CD107a in NK-92MI^hCD16-GFP stimulated by retinoblastoma cells were assessed via enzyme-linked immunosorbent assays (ELISAs) and FC in the presence of dinutuximab or an isotype control.

Results

GD2 was heterogeneously expressed in retinoblastoma tissues and cell lines and positively correlated with proliferation and staging. GSEA revealed the immunosuppressive status of retinoblastoma microenvironment. The immune cell profile of retinoblastoma tissues and vitreous bodies suggested BRB destruction. LDH release and apoptosis in retinoblastoma cells caused by NK-92MI^hCD16-GFP cells were significantly enhanced by dinutuximab. Finally, the release of perforin-granzyme B and the expression of CD107a in NK-92MI^hCD16-GFP cells stimulated by retinoblastoma cells were obviously increased by dinutuximab.

Conclusion

This study indicates that retinoblastoma impairs the integrity of the BRB and contributes to dysregulated immune cell infiltrates. GD2 is a specific target for natural killer (NK) cell-based immunotherapy and that the combination of dinutuximab and NK-92MI^hCD16-GFP cells exerts potent antitumor effects through antibody-dependent cell-mediated cytotoxicity.

Identification and Characterization of Trajectories of Cardiac Allograft Vasculopathy After Heart Transplantation: A Population-Based Study

BACKGROUND

Cardiac allograft vasculopathy (CAV) is a major contributor of heart transplant recipient mortality. Little is known about the prototypes of CAV trajectories at the population level. We aimed to identify the different evolutionary profiles of CAV and to determine the respective contribution of immune and nonimmune factors in CAV development.

METHODS

Heart transplant recipients were from 4 academic centers (Pitié-Salpêtrière and Georges Pompidou Hospital, Paris, Katholieke Universiteit Leuven, and Cedars-Sinai, Los Angeles; 2004-2016). Patients underwent prospective, protocol-based monitoring consisting of repeated coronary angiographies together with systematic assessments of clinical, histological, and immunologic parameters. The main outcome was a prediction for CAV trajectory. We identified CAV trajectories by using unsupervised latent class mixed models. We then identified the independent predictive variables of the CAV trajectories and their association with mortality.

RESULTS

A total of 1301 patients were included (815 and 486 in the European and US cohorts, respectively). The median follow-up after transplantation was 6.6 (interquartile range, 4-9.1) years with 4710 coronary angiographies analyzed. We identified 4 distinct profiles of CAV trajectories over 10 years. The 4 trajectories were characterized by (1) patients without CAV at 1 year and nonprogression over time (56.3%), (2) patients without CAV at 1 year and late-onset slow CAV progression (7.6%), (3) patients with mild CAV at 1 year and mild progression over time (23.1%), and (4) patients with mild CAV at 1 year and accelerated progression (13.0%). This model showed good discrimination (0.92). Among candidate predictors assessed, 6 early independent predictors of these trajectories were identified: donor age (P<0.001), donor male sex (P<0.001), donor tobacco consumption (P=0.001), recipient dyslipidemia (P=0.009), class II anti-human leukocyte antigen donor-specific antibodies (P=0.004), and acute cellular rejection ≥2R (P=0.028). The 4 CAV trajectories manifested consistently in the US independent cohort with similar discrimination (0.97) and in different clinical scenarios, and showed gradients for overall-cause mortality (P<0.001).

CONCLUSIONS

In a large multicenter and highly phenotyped prospective cohort of heart transplant recipients, we identified 4 CAV trajectories and their respective independent predictive variables. Our results provide the basis for a trajectory-based assessment of patients undergoing heart transplantation for early risk stratification, patient monitoring, and clinical trials. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04117152.

Xenotransplantation: Progress Along Paths Uncertain from Models to Application

For more than a century, transplantation of tissues and organs from animals into man, xenotransplantation, has been viewed as a potential way to treat disease. Ironically, interest in xenotransplantation was fueled especially by successful application of allotransplantation, that is, transplantation of human tissue and organs, as a treatment for a variety of diseases, especially organ failure because scarcity of human tissues limited allotransplantation to a fraction of those who could benefit. In principle, use of animals such as pigs as a source of transplants would allow transplantation to exert a vastly greater impact than allotransplantation on medicine and public health. However, biological barriers to xenotransplantation, including immunity of the recipient, incompatibility of biological systems, and transmission of novel infectious agents, are believed to exceed the barriers to allotransplantation and presently to hinder clinical applications. One way potentially to address the barriers to xenotransplantation is by genetic engineering animal sources. The last 2 decades have brought progressive advances in approaches that can be applied to genetic modification of large animals. Application of these approaches to genetic engineering of pigs has contributed to dramatic improvement in the outcome of experimental xenografts in nonhuman primates and have encouraged the development of a new type of xenograft, a reverse xenograft, in which human stem cells are introduced into pigs under conditions that support differentiation and expansion into functional tissues and potentially organs. These advances make it appropriate to consider the potential limitation of genetic engineering and of current models for advancing the clinical applications of xenotransplantation and reverse xenotransplantation.

FCGR3A and FCGR2A Genotypes Differentially Impact Allograft Rejection and Patients' Survival After Lung Transplant

Fc gamma receptors (FcγRs) play a major role in the regulation of humoral immune responses. Single-nucleotide polymorphisms (SNPs) of FCGR2A and FCGR3A can impact the expression level, IgG affinity and function of the CD32 and CD16 FcγRs in response to their engagement by the Fc fragment of IgG. The CD16 isoform encoded by FCGR3A [158V/V] controls the intensity of antibody-dependent cytotoxic alloimmune responses of natural killer cells (NK) and has been identified as a susceptibility marker predisposing patients to cardiac allograft vasculopathy after heart transplant. This study aimed to investigate whether FCGR2A and FCGR3A polymorphisms can also be associated with the clinical outcome of lung transplant recipients (LTRs). The SNPs of FCGR2A ([131R/H], rs1801274) and FCGR3A ([158V/F], rs396991) were identified in 158 LTRs and 184 Controls (CTL). The corresponding distribution of genotypic and allelic combinations was analyzed for potential links with the development of circulating donor-specific anti-HLA alloantibodies (DSA) detected at months 1 and 3 after lung transplant (LTx), the occurrence of acute rejection (AR) and chronic lung allograft dysfunction (CLAD), and the overall survival of LTRs. The FCGR3A [158V/V] genotype was identified as an independent susceptibility factor associated with higher rates of AR during the first trimester after LTx (HR 4.8, p < 0.0001, 95% CI 2.37-9.61), but it could not be associated with the level of CD16- mediated NK cell activation in response to the LTR's DSA, whatever the MFI intensity and C1q binding profiles of the DSA evaluated. The FCGR2A [131R/R] genotype was associated with lower CLAD-free survival of LTRs, independently of the presence of DSA at 3 months (HR 1.8, p = 0.024, 95% CI 1.08-3.03). Our data indicate that FCGR SNPs differentially affect the clinical outcome of LTRs and may be of use to stratify patients at higher risk of experiencing graft rejection. Furthermore, these data suggest that in the LTx setting, specific mechanisms of humoral alloreactivity, which cannot be solely explained by the complement and CD16-mediated pathogenic effects of DSA, may be involved in the development of acute and chronic lung allograft rejection.

Lymphocytic subsets play distinct roles in heart diseases

Heart diseases are one of the leading causes of death for humans in the world. Increasing evidence has shown that myocardial injury induced innate and adaptive immune responses upon early cellular damage but also during chronic phases post-injury. The immune cells can not only aggravate the injury but also play an essential role in the induction of wound healing responses, which means they play a complex role throughout the acute inflammatory response and reparative response after cardiac injury. This review will summarize the current experimental and clinical evidence of lymphocytes, one of the major types of immune cells, participate in heart diseases and try to explain the possible role of these immune cells following cardiac injury.

Small-Molecule Immunosuppressive Drugs and Therapeutic Immunoglobulins Differentially Inhibit NK Cell Effector Functions in vitro

Small-molecule immunosuppressive drugs (ISD) prevent graft rejection mainly by inhibiting T lymphocytes. Therapeutic immunoglobulins (IVIg) are used for substitution, antibody-mediated rejection (AbMR) and HLA-sensitized recipients by targeting distinct cell types. Since the effect of ISD and IVIg on natural killer (NK) cells remains somewhat controversial in the current literature, the aim of this comparative study was to investigate healthy donor's human NK cell functions after exposure to ISD and IVIg, and to comprehensively review the current literature. NK cells were incubated overnight with IL2/IL12 and different doses and combinations of ISD and IVIg. Proliferation was evaluated by ³[H]-thymidine incorporation; phenotype, degranulation and interferon gamma (IFNγ) production by flow cytometry and ELISA; direct NK cytotoxicity by standard ⁵¹[Cr]-release and non-radioactive DELFIA assays using K562 as stimulator and target cells; porcine endothelial cells coated with human anti-pig antibodies were used as targets in antibody-dependent cellular cytotoxicity (ADCC) assays. We found that CD69, CD25, CD54, and NKG2D were downregulated by ISD. Proliferation was inhibited by methylprednisolone (MePRD), mycophenolic acid (MPA), and everolimus (EVE). MePRD and MPA reduced degranulation, MPA only of CD56^bright NK cells. MePRD and IVIg inhibited direct cytotoxicity and ADCC. Combinations of ISD demonstrated cumulative inhibitory effects. IFNγ production was inhibited by MePRD and ISD combinations, but not by IVIg. In conclusion, IVIg, ISD and combinations thereof differentially inhibit NK cell functions. The most potent drug with an effect on all NK functions was MePRD. The fact that MePRD and IVIg significantly block NK cytotoxicity, especially ADCC, has major implications for AbMR as well as therapeutic strategies targeting cancer and immune cells with monoclonal antibodies.

A comprehensive overview of FCGR3A gene variability by full-length gene sequencing including the identification of V158F polymorphism

The FCGR3A gene encodes for the receptor important for antibody-dependent natural killer cell-mediated cytotoxicity. FCGR3A gene polymorphisms could affect the success of monoclonal antibody therapy. Although polymorphisms, such as the FcγRIIIA-V158F and -48L/R/H, have been studied extensively, an overview of other polymorphisms within this gene is lacking. To provide an overview of FCGR3A polymorphisms, we analysed the 1000 Genomes project database and found a total of 234 polymorphisms within the FCGR3A gene, of which 69%, 16%, and 15% occur in the intron, UTR, and exon regions respectively. Additionally, only 16% of all polymorphisms had a minor allele frequency (MAF) > 0.01. To facilitate (full-length) analysis of FCGR3A gene polymorphism, we developed a FCGR3A gene-specific amplification and sequencing protocol for Sanger sequencing and MinION (Nanopore Technologies). First, we used the Sanger sequencing protocol to study the presence of the V158F polymorphism in 76 individuals resulting in frequencies of 38% homozygous T/T, 7% homozygous G/G and 55% heterozygous. Next, we performed a pilot with both Sanger sequencing and MinION based sequencing of 14 DNA samples which showed a good concordance between Sanger- and MinION sequencing. Additionally, we detected 13 SNPs listed in the 1000 Genome Project, from which 11 had MAF > 0.01, and 10 SNPs were not listed in 1000 Genome Project. In summary, we demonstrated that FCGR3A gene is more polymorphic than previously described. As most novel polymorphisms are located in non-coding regions, their functional relevance needs to be studied in future functional studies.