Search Results (75)

Background: The interaction between human immunoglobulin G (IgG)1 Fc and the Fc gamma receptor (FcγR) IIIa/CD16a elicits protective immune responses. Antibody N-glycosylation stabilizes the FcγR-binding interface and is thus essential for interaction with wildtype IgG1 Fc. Furthermore, the N-glycan introduces substantial compositional and functional heterogeneity, with distinct glycoforms providing different affinities and discrete responses in vivo. Accordingly, various engineering endeavors to improve antibody binding strive to boost the therapeutic efficacy of monoclonal antibodies but do not directly address compositional heterogeneity. Objective: Here, we describe a previously unexplored approach to engineer IgG1 Fc. We eliminated carbohydrate heterogeneity by removing the N-glycan but stabilizing the FcγR-binding interface with disulfide bonds. Conclusions: These newly generated Fc domains served as a starting point for protein engineering through yeast surface display to enhance receptor-binding affinity. We recovered Fc variants from this approach that demonstrated FcγRIIIa binding affinities comparable to the starting sequence and thus serve as a proof-of-principle for this strategy. Full article

Autoimmune myocarditis frequently progresses to inflammatory cardiomyopathy through dysregulated immune–stromal interactions. This study employs single-nuclei RNA-sequencing (snRNA-seq) to profile 46,233 cardiac nuclei from the experimental autoimmune myocarditis (EAM) mouse model at four timepoints: day 0 (healthy), day 14 (inflammation), day 21 (acute inflammation), and day 40 (late cardiac remodelling). Single-nuclei RNA profiling identified 18 transcriptionally distinct cell populations. Global cell–cell communication analysis revealed a dramatic peak of intercellular signalling at day 14 (5907 interactions), with fibroblast subpopulations and macrophages as dominant hubs, followed by partial resolution at day 21 (2264 interactions) and renewed remodelling at day 40 (4862 interactions). Subclustering of the macrophage compartment identified five subpopulations: Mac-TLF, Mac-MHCII, Mac-rMHCII, Mac-ResL, and Classical Monocytes. Tissue-resident macrophages (Mac-TLF, CCR2-) dominated at healthy state (~55%) but were rapidly depleted at day 14, coinciding with a dramatic influx of recruited CCR2⁺ macrophages (Mac-rMHCII), which expanded to over 70% of the compartment and maintained dominance through day 40. At inflammation (day 14), the expanded Mac-rMHCII subpopulation displayed a strongly pro-inflammatory signature (Il1b, Stat2, Parp14, Apoe), and the overall macrophage compartment was enriched for cytokine response, Fc-gamma receptor, and Notch signalling pathways, while downregulating homeostatic and mitochondrial metabolic programmes, potentially contributing to impaired efferocytosis and cardiomyocyte dysfunction. Macrophage-centred communication networks expanded markedly at day 14 (1047 interactions), with resting fibroblasts (FB-R) as the primary signalling partner, driving pro-inflammatory stromal activation marked by upregulation of Ccl2, Ccl7, and Csf2. Intra-macrophage subcluster communication also intensified at this timepoint (447 interactions). These findings delineate the temporal and functional heterogeneity of cardiac macrophages during EAM progression and identify key immune–stromal interactions driving pathological cardiac remodelling. The coexistence of pro-inflammatory and transitional reparative macrophage subsets highlights the limitations of broad immunosuppression and supports precision strategies targeting CCR2-mediated recruitment, the SPP1 signalling axis, and macrophage–fibroblast crosstalk as therapeutic avenues in myocarditis and its progression. Full article

Background: Although prolonged inflammatory symptoms are an infrequent and problematic adverse effect of vaccination that can occur in some people, the transient activation of acute phase reactants (APRs) is expected with adjuvanted vaccines and helps to potentiate immune responses. Methods: This experiment examined the association between vaccine reactogenicity and immunogenicity in monkeys immunized with an adjuvanted recombinant protein including a receptor binding domain–human IgG1-Fc fusion protein (RBD-Fc) sequenced from the ancestral Wuhan strain of SARS-CoV-2. The acute inflammatory reaction to immunization was assessed by determining the decline in serum iron levels at 24 h and the increase in the neutrophil-to-lymphocyte ratio (NLR) as the adherent neutrophil pool trafficked into circulation. Results: Robust primary and secondary antibody responses were elicited. Larger decreases in serum iron and higher NLRs were associated with a stronger inhibition of RBD binding with angiotensin-converting enzyme (ACE2) when five early viral variants of SARS-CoV-2 were tested, including Wuhan, Alpha, Beta, Gamma and Delta. Inhibition of ACE2-RBD binding was less evident when the Omicron variant was tested. Individual variation in the APR was also predictive of the persistence of cell-mediated immunity based on the number of interferon-expressing mononuclear cells activated by viral antigen in ELISpot assays. Conclusions: Rapid antibody responses to primary immunization and large secondary responses to booster immunizations were elicited by this adjuvanted recombinant RBD-Fc vaccine, and our analysis affirmed the view that a transient APR can enhance antibody binding with antigen proteins. Full article

Acute kidney injury (AKI) caused by ischemia–reperfusion injury (IRI) involves rapid activation of innate immune responses, in which myeloid-derived immune cells critically shape injury severity. Y-box binding protein 1 (YB-1) regulates pro-inflammatory gene expression intracellularly and can be secreted to function extracellularly, yet how these two compartments jointly influence early IRI pathology remains poorly understood. To dissect the roles of intracellular myeloid versus extracellular YB-1, we subjected myeloid-specific Ybx1 knockout, Ybx1^fl/fl × LysM^cre, mice and wild-type (WT) littermates to unilateral renal IRI following administration of either a neutralizing anti-YB-1 antibody or control IgG. Kidney injury, inflammation, immune cell recruitment, neutrophil extracellular trap (NET) formation, antibody localization, and Fcγ receptor expression were assessed by qRT-PCR, histology, immunostaining, Western blotting, and flow cytometry. Myeloid-specific knockout of Ybx1 markedly reduced renal inflammation, neutrophil infiltration, NET formation, and tubular injury. This protective phenotype was lost when extracellular YB-1 was simultaneously reduced: anti-YB-1 treatment in knockout mice restored pro-inflammatory cytokine expression, increased tubular damage markers such as NGAL and KIM-1, exacerbated neutrophil recruitment and NET formation, and led to luminar accumulation of YB-1/anti-YB-1 immune complexes in tubular cells. Mechanistically, Ybx1-deficient myeloid cells exhibited significantly reduced CD16 expression, pointing to impaired Fcγ receptor-mediated phagocytosis as the cause of defective immune complex clearance. In contrast, wild-type mice efficiently cleared extracellular YB-1 complexes and showed no injury aggravation upon antibody treatment. Our findings identify myeloid YB-1 as a central regulator of early inflammatory injury in renal IRI and reveal that its protective depletion becomes pathogenic when extracellular YB-1 is simultaneously neutralized, likely due to unmasked defects in immune complex clearance. Full article

Functional antibody-dependent enhancement (ADE) represents a fundamental and context-dependent characteristic of antiviral antibody responses, reflecting the dual capacity of antibodies to mediate both the neutralization and Fc receptor-dependent enhancement of infection. In flavivirus research, this duality complicates the interpretation of conventional serological metrics and limits the reliability of single-parameter correlates of immunity, particularly in populations with complex exposure histories. Over the past decade, functional ADE assays have evolved from specialized mechanistic tools into integrated immune assessment platforms supporting translational immunology, vaccine evaluation, and population-level immune surveillance. These platforms incorporate Fcγ receptor-relevant target cell systems, standardized viral inputs, dilution series-based profiling, quantitative enhancement metrics, and structured quality control frameworks to enable reproducible, comparable, and context-aware functional measurements across cohorts and laboratories. A central concept emerging from these developments is that ADE reflects a dynamic functional immune state rather than an intrinsic property of antibodies or a direct indicator of pathological risk. Accordingly, functional ADE platforms support the contextual interpretation of antibody activity across physiologically relevant conditions, facilitating discrimination between transient functional enhancement and clinically meaningful immunological risk. By integrating functional ADE metrics with serological, cellular, and epidemiological data, these platforms provide a structured framework for interpreting immune profiles in vaccine evaluation, booster strategy design, and population-level risk stratification. This review synthesizes the development, standardization, and global dissemination of functional ADE platforms and discusses key principles governing biological relevance, analytical robustness, and inter-site transferability. Emerging directions integrating functional ADE profiling with systems immunology, immunogenomics, and computational modeling are highlighted as pathways toward predictive, decision-support-oriented frameworks. By positioning ADE platforms as immune assessment infrastructures rather than isolated assays, this review underscores their value for mechanistic inquiry, translational interpretation, and preparedness-oriented responses to emerging viral threats in the absence of definitive correlates of protection. Full article

Background/Objectives: Consumption of a Mediterranean diet (MD) has been associated with reduced incidence of non-communicable diseases and reduced overall mortality, with epigenomic effects representing plausible mediators. The aim of this pilot study was to explore potential epigenetic associations between DNA methylation markers in blood and adherence to an MD in pregnancy. Methods: Fifty-two pregnant women with high or low adherence to an MD throughout pregnancy, who participated in the BioMood ORIGINS study, were selected using an extremes-of-exposure design. DNA methylation (DNAm) profiles from whole blood were generated using the TWIST human methylome panel. We conducted both genome-wide and candidate gene-based differential methylation analyses to identify epigenetic variations between the study groups. Furthermore, we explored potential associations between blood methylation patterns and circulating inflammatory markers (GlycA, GlycB and SPC) previously observed to exhibit differential abundance in the same cohort of women. Results: There were no genome-wide significant differences in methylated dinucleotides between MD groups (p-value < 5 × 10⁻⁸); however, a region-based analysis identified 2210 differentially methylated regions (DMRs) (FDR < 0.05, absolute maximum logFC > 1) annotated to 1537 genes, significantly enriched in metabolic, inflammatory and neuronal signaling pathways. Leveraging publicly available data, we replicated nine novel DMR associations. Changes in circulating phospholipid inflammatory markers were significantly associated with a small methylation difference in Lipin-1 (LPIN1), albeit with a small effect size (p-value < 5 × 10⁻⁸). A look-up analysis of previously reported MD-associated genes in this cohort detected small but statistically significantly different methylation of CpGs located within collagen type XVIII alpha 1 (COL18A1) and peroxisome proliferator-activated receptor gamma, coactivator 1 beta (PPARGC1B) gene regions. Conclusions: We provide preliminary evidence for modest methylation changes in specific genes associated with adherence to an MD. Full article

Female infertility diseases such as polycystic ovary syndrome (PCOS), endometriosis, diminished ovarian reserve (DOR), and recurrent implantation failure (RIF) have different clinical phenotypes. However, they might be epigenetically convergent, and thus the therapeutic targets may be potential. This study utilized transcriptome data, microRNA (miRNA), and DNA methylation data from the granulosa cells of four Gene Expression Omnibus (GEO) datasets, GSE138518, GSE105765, GSE232306, and GSE92324, to conduct integrated bioinformatics analysis. We focused on differentially expressed genes (DEGs), constructed a miRNA–mRNA network, performed ROC curve analysis, and conducted function enrichment and drug repurposing studies. Our findings identified eight dysregulated genes (H19, SULT1A4, HCK, SPI1, CARD16, NFE2, LST1, and KRT8) common to PCOS, DOR, and RIF, which may serve to distinguish PCOS specifically. Moreover, these DEGs are associated with pathways such as innate immune activation, inflammatory responses, the NOD-like receptor signaling pathway, and Fc gamma R-mediated phagocytosis. Notably, MiRNAs differentially expressed in endometriosis (specifically hsa-miR-202-5p and hsa-miR-141-3p) were found to directly target this gene set, highlighting the role of epigenetic regulation across infertility diseases. Additionally, our drug repurposing analysis identified several FDA-approved drugs, including Abacavir and Peginterferon Alfa-2b, suggesting that the HCK gene may be a viable target for drug development to address female infertility. Furthermore, we identified 192 genes that correlated with DNA methylation and expression levels in PCOS. Thus, this study underscores the epigenetic convergence of different female infertility diseases and highlights potential biomarkers and therapeutic options that could enhance treatment in reproductive medicine. Full article

Type I interferons (IFNs), mainly IFN-α and IFN-β, play an essential role in defending against viral invasion by inducing the host’s innate antiviral response. Porcine reproductive and respiratory syndrome virus (PRRSV) is known to impair the IFN responses of infected hosts through the antibody-dependent enhancement (ADE) infection pathway, but the precise mechanisms employed are poorly understood. In this study, we showed that PRRSV alone induced a strong secretion of IFN-α and IFN-β in infected porcine alveolar macrophages (PAMs) by activating the retinoic acid-inducible gene I (RIG-I)/melanoma differentiation-associated gene 5 (MDA5) signaling pathway. By contrast, ADE infection of PRRSV significantly down-regulated the production levels of IFN-α and IFN-β in PAMs by negatively regulating the RIG-I/MDA5 signaling pathway and considerably enhancing the replication level of PRRSV in PAMs. Next, small interfering RNA (siRNA) experiments revealed that Fc gamma receptor I (FcγRI) was responsible for the ADE infection of PRRSV in PAMs. In addition, we observed that FcγRI mediated the potent inhibition of IFN-α and IFN-β production through blocking the activation of the RIG-I/MDA5 signaling pathway in PAMs. Further, we found that FcγRI effectively inhibited PRRSV-induced synthesis of IFN-α and IFN-β by negatively regulating PRRSV-induced activation of the RIG-I/MDA5 signaling pathway in PAMs and significantly increased the viral production of PRRSV in PAMs. In conclusion, these results suggest that ADE infection of PRRSV may antagonize the secretion of type I IFNs (IFN-α/β) by interfering with the RIG-I/MDA5 pathway via FcγRI in PAMs, thereby facilitating the proliferation level of PRRSV in PAMs. Full article

Fc gamma receptors (FcγRs) control humoral and cellular immune responses and maintain the immune system balance. Functional polymorphisms of FcγRs, whose prevalence was dependent on ethnic origin, were found to be associated with systemic lupus erythematosus (SLE) or kidney injuries in several ethnic groups. We aimed at investigating the association between the functional single-nucleotide polymorphisms (SNPs) of FcγRIIa-H131R (rs1801274), FcγRIIb-I232T (rs1050501), FcγRIIIa-V158F (rs396991) and FcγRIIIb variants (NA1 and NA2) and lupus erythematosus systemic in an indigenous African Caribbean population. We compared the frequencies of the functional SNPs of FCGR2A (FcγRIIa-H131R, rs1801274), FCGR2B (FcγRIIb-I232T, rs1050501), FCGR3A (FcγRIIIa-V158F, rs396991) and FCGR3B variants (FcγRIIIb NA1 and NA2) between lupus and healthy controls in an indigenous African Caribbean population. We highlighted an association between the FCGR3B-NA1/NA1 and FCGR3A-158F alleles and systemic lupus erythematosus, in addition to an association between FCGR2A-131R and lupus nephritis. Furthermore, an increase in the 131R-158V haplotype in lupus nephritis (30.4%) vs. lupus non-nephritis (15.8%) was noticed. Surprisingly, in spite of the high frequency of the FCGR2B-232T allele in our population, our study did not highlight any association of this allele either with SLE or lupus nephritis (a severe and frequent form of SLE). CD72-Hap1, which has been shown to confer resistance to SLE against T232 allele, was not enhanced in the control group. Our results emphasize an association between FCGR2A-131R and lupus nephritis with a distinctive FCGR polymorphism distribution in an indigenous African Caribbean population, confirming the important variation in the FCGR locus depending on ethnic origin. Full article

Background: Oropouche virus (OROV), part of the Peribunyaviridae family, is an emerging pathogen causing Oropouche fever, a febrile illness endemic in South and Central America. Transmitted primarily through midge bites (Culicoides paraensis), OROV has no specific antiviral treatment or vaccine. This study aims to identify host-targeted therapeutics against OROV using computational approaches, offering a potential strategy for sustainable antiviral drug discovery. Methods: Virus-associated host targets were identified using the OMIM and GeneCards databases. The Enrichr and DSigDB platforms were used for drug prediction, filtering compounds based on Lipinski’s rule for drug likeness. A protein–protein interaction (PPI) network analysis was conducted using the STRING database and Cytoscape 3.10.3 software. Four key host targets—IL10, FASLG, PTPRC, and FCGR3A—were prioritized based on their roles in immune modulation and OROV pathogenesis. Molecular docking simulations were performed using the PyRx software to evaluate the binding affinities of selected small-molecule inhibitors—Acetohexamide, Deptropine, Methotrexate, Retinoic Acid, and 3-Azido-3-deoxythymidine—against the identified targets. Results: The PPI network analysis highlighted immune-mediated pathways such as Fc-gamma receptor signaling, cytokine control, and T-cell receptor signaling as critical intervention points. Molecular docking revealed strong binding affinities between the selected compounds and the prioritized targets, suggesting their potential efficacy as host-targeting antiviral candidates. Acetohexamide and Deptropine showed strong binding to multiple targets, indicating broad-spectrum antiviral potential. Further in vitro and in vivo validations are needed to confirm these findings and translate them into clinically relevant treatments. Conclusions: This study highlights the potential of using computational approaches to identify host-targeted therapeutics for Oropouche virus (OROV). By targeting key host proteins involved in immune modulation—IL10, FASLG, PTPRC, and FCGR3A—the selected compounds, Acetohexamide and Deptropine, demonstrate strong binding affinities, suggesting their potential as broad-spectrum antiviral candidates. Further experimental validation is needed to confirm their efficacy and potential for clinical application, offering a promising strategy for sustainable antiviral drug discovery. Full article

Identifying reliable biomarkers in peripheral blood is critical for advancing the diagnosis and management of multiple sclerosis (MS), particularly given the invasive nature of cerebrospinal fluid (CSF) sampling. This review explores the role of B cells and immunoglobulins (Igs), particularly IgG and IgM, as biomarkers for MS. B cell oligoclonal bands (OCBs) in the CSF are well-established diagnostic tools, yet peripheral biomarkers remain underdeveloped. Emerging evidence highlights structural and functional variations in immunoglobulin that may correlate with disease activity and progression. A recent novel discovery of blood IgG aggregates in MS patients that fail to bind Protein A reveals promising diagnostic potential and confirms previous findings of the unique features of immunoglobulin G in MS and the potential link between the superantigen Protein A and MS. These aggregates, enriched in IgG1 and IgG3 subclasses, exhibit unique structural properties, including mutations in the framework region 3 (FR3) of IGHV3 genes, and are associated with complement-dependent neuronal apoptosis. Data based on ELISA have demonstrated that IgG aggregates in plasma can distinguish MS patients from healthy controls and other central nervous system (CNS) disorders with high accuracy and differentiate between disease subtypes. This suggests a role for IgG aggregates as non-invasive biomarkers for MS diagnosis and monitoring. Full article

Background/Objectives: Acinetobacter baumannii is an opportunistic nosocomial pathogen characterized by its multidrug-resistant (MDR) phenotype, increasing patient mortality and healthcare costs as a result. Previously, we constructed an immunoinformatics-based Acinetobacter Multi-Epitope Vaccine (AMEV2) candidate and demonstrated robust protection against this MDR pathogen. In this study, we delineate the mechanisms of AMEV2-mediated protective immunity. Methods: In vivo passive immunization with AMEV2 antisera and in vitro opsonophagocytic killing assays (OPKAs) were used to assess the critical role of antibody-mediated protection induced by AMEV2 vaccination. Results: The passive transfer of AMEV2 immune sera to naïve mice afforded 67% protection in a pulmonary challenge mouse model. Although AMEV2 sera reacts with bacterial antigens, it is not bactericidal on its own and does not enhance the complement-mediated direct killing of A. baumannii. However, OPKAs demonstrate AMEV2 sera enhancement of the killing of A. baumannii in the presence of primary bone marrow-derived macrophages. This killing occurs via complement and Fc gamma receptor-mediated phagocytosis. A highly immunogenic AMEV2 component peptide, pTonB, elicits pTonB-specific antibodies and protection in vivo. The depletion of pTonB antibodies from AMEV2 immune sera by pTonB absorption significantly reduced the opsonophagocytic killing of A. baumannii in vitro. Conclusions: The data presented here demonstrate the importance of humoral immunity and its protective mechanisms against A. baumannii. These findings further expand the in vivo evaluation of in silico-designed vaccines as a viable alternative to combat the current global MDR pathogen health crisis. Full article

Receptors for the immunoglobulin G constant fraction (FcγRs) are widely expressed in cells of the immune system. Complement-independent phagocytosis prompted FcγR research to show that the engagement of IgG immune complexes with FcγRs triggers a variety of cell host immune responses, such as phagocytosis, antibody-dependent cell cytotoxicity, and NETosis, among others. However, variants of these receptors have been implicated in the development of and susceptibility to autoimmune diseases such as systemic lupus erythematosus. Currently, the knowledge of FcγR variants is a required field of antibody therapeutics, which includes the engineering of recombinant soluble human Fc gamma receptors, enhancing the inhibitory and blocking the activating FcγRs function, vaccines, and organ transplantation. Importantly, recent interest in FcγRs is the antibody-dependent enhancement (ADE), a mechanism by which the pathogenesis of certain viral infections is enhanced. ADEs may be responsible for the severity of the SARS-CoV-2 infection. Therefore, FcγRs have become a current research topic. Therefore, this review briefly describes some of the historical knowledge about the FcγR type I family in humans, including the structure, affinity, and mechanism of ligand binding, FcγRs in diseases such as systemic lupus erythematosus (SLE), and the potential therapeutic approaches related to these receptors in SLE. Full article

Antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells is a key mechanism in anti-cancer therapies with monoclonal antibodies, including cetuximab (EGFR-targeting) and avelumab (PDL1-targeting). Fc gamma receptor IIIa (FcγRIIIa) polymorphisms impact ADCC, yet their clinical relevance in NK cell functionality remains debated. We developed two complementary flow cytometry assays: one to predict the FcγRIIIa-V158F polymorphism using a machine learning model, and a 15-color flow cytometry panel to assess antibody-induced NK cell functionality and cancer-immune cell interactions. Samples were collected from healthy donors and metastatic colorectal cancer (mCRC) patients from the FIRE-6-Avelumab phase II study. The machine learning model accurately predicted the FcγRIIIa-V158F polymorphism in 94% of samples. FF homozygous patients showed diminished cetuximab-mediated ADCC compared to VF or VV carriers. In mCRC patients, NK cell dysfunctions were evident as impaired ADCC, decreased CD16 downregulation, and reduced CD137/CD107a induction. Elevated PD1+ NK cell levels, reduced lysis of PDL1-expressing CRC cells and improved NK cell activation in combination with the PDL1-targeting avelumab indicate that the PD1-PDL1 axis contributes to impaired cetuximab-induced NK cell function. Together, these optimized assays effectively identify NK cell dysfunctions in mCRC patients and offer potential for broader application in evaluating NK cell functionality across cancers and therapeutic settings. Full article

Natural killer (NK) and CD8⁺ T cell function is compromised in human immunodeficiency virus type 1 (HIV-1) infection by increased expression of inhibitory receptors such as TIGIT (T cell immunoreceptor with Ig and ITIM domains). Blocking inhibitory receptors or their ligands with monoclonal antibodies (mAb) has potential to improve antiviral immunity in general and facilitate HIV eradication strategies. We assessed the impact of TIGIT engagement and blockade on cytotoxicity, degranulation, and interferon-gamma (IFN-γ) production by CD8⁺ T cells from persons living with HIV (PLWH). The effect of TIGIT engagement on non-specific anti-CD3-redirected cytotoxicity was assessed in redirected cytotoxicity assays, and the effect of TIGIT blockade on HIV-specific CD8⁺ T cell responses was assessed by flow cytometry. In 14/19 cases where peripheral blood mononuclear cells (PBMC) mediated >10% redirected cytotoxicity, TIGIT engagement reduced the level of cytotoxicity to <90% of control values. We selected PLWH with >1000 HIV Gag or Nef-specific IFN-γ spot forming cells per million PBMC to quantify the effects of TIGIT blockade on HIV-specific CD8⁺ T cell responses by flow cytometry. Cell surface TIGIT expression decreased on CD8⁺ T cells from 23/40 PLWH following TIGIT blockade and this loss was associated with increased anti-TIGIT mAb fluorescence on monocytes. In total, 6 of these 23 PLWH had enhanced HIV-specific CD8⁺ T cell degranulation and IFN-γ production with TIGIT blockade, compared to 0/17 with no decrease in cell surface TIGIT expression. Reduced CD8⁺ T cell TIGIT expression with TIGIT blockade involved trogocytosis by circulating monocytes, suggesting that an effector monocyte population and intact fragment crystallizable (Fc) functions are required for mAb-based TIGIT blockade to effectively enhance HIV-specific CD8⁺ T cell responses. Full article