Search Results (23)

Lymphocyte activation gene-3 (LAG-3) is a pivotal immune checkpoint receptor that exerts a negative regulatory effect on T-cell function. Although LAG-3-blocking antibodies have shown promising clinical potential, the inherent limitations of conventional monoclonal antibodies necessitate the development of novel antibody formats with enhanced biological and pharmacological properties. In this study, a panel of single-domain antibodies (sdAbs) targeting human LAG-3 was generated via phage display technology. Among these candidates, 2H-G7 was identified as a high-affinity sdAb that binds to LAG-3 with an equilibrium dissociation constant (K_D) in the nanomolar range. Notably, 2H-G7 potently blocks the interactions of LAG-3 with both of its key ligands, fibrinogen-like protein 1 (FGL1) and major histocompatibility complex class II (MHC-II). Its capacity to restore impaired T-cell function was validated by quantifying interleukin-2 (IL-2) secretion and CD69 expression in stimulated primary human peripheral blood mononuclear cells (PBMCs). Epitope mapping studies localized the binding site of 2H-G7 to the D1D2 extracellular domains of LAG-3, distinct from relatlimab, a clinically approved LAG-3-blocking antibody serving as the benchmark. In a xenogeneic mouse model of non-small-cell lung cancer (NSCLC), 2H-G7-Fc exhibited superior tumor growth inhibition efficacy compared with relatlimab. These findings demonstrate that 2H-G7 is a promising lead candidate for the development of next-generation LAG-3-targeted tumor immunotherapies. Full article

Tumor-associated macrophages (TAMs) are abundant in the tumor microenvironment (TME) and often adopt an M2-like immunosuppressive phenotype that promotes tumor growth. Reprogramming TAMs toward an M1-like pro-inflammatory state is an attractive therapeutic strategy. Tumor Treating Fields (TTFields), an FDA-approved, electric-field–based therapy, has recently been suggested to modulate immune responses in addition to its established anti-mitotic activity. Here, we investigated the direct effects of TTFields on macrophage activation and function. Murine bone marrow–derived macrophages (BMDMs) were polarized toward a pro-inflammatory M1-like phenotype or an anti-inflammatory M2-like phenotype and exposed to TTFields. TTFields rapidly activated guanine nucleotide exchange factor-H1 (GEF-H1), and downstream nuclear factor kappa B (NF-κB) and activator protein-1 (AP-1, via c-Jun N-terminal kinase [JNK]) signaling. Functionally, TTFields reprogrammed M2-like macrophages by increasing major histocompatibility complex class II (MHC-II) and cluster of differentiation 80 (CD80); reducing arginase-1 (Arg1); and elevating secretion of chemokine (C-X-C motif) ligand 1 (CXCL1), interleukin-6 (IL-6), IL-1β, and IL-12 subunit p70 (IL-12p70). In interferon gamma (IFN-γ)-primed macrophages, TTFields provided a secondary signal, driving myeloid differentiation primary response 88 (MyD88)-dependent expression of inducible nitric oxide synthase (iNOS). In vivo, TTFields reduced tumor burden in an orthotopic murine lung cancer model and increased iNOS expression in both M1-like and a subset of M2-like TAMs. These findings demonstrate that TTFields directly reprogram macrophages toward a pro-inflammatory phenotype, suggesting a novel immunomodulatory mechanism that may enhance anti-tumor immunity in the TME. Full article

Proteases represent a diverse family of enzymes that catalyze the hydrolysis of peptide bonds, modulating numerous biological processes. Among their substrates, CD74—also known as the invariant chain—has received increased research attention due to its multifunctional roles in both innate and adaptive immunity. This review provides an overview of current knowledge on protease-mediated interactions with CD74. The protein was originally identified as a chaperone for major histocompatibility complex class II (MHC-II) molecules. Proteolytic cleavage of CD74, most notably by cathepsin S, is essential for the release of MHC-II and the initiation of antigen presentation. However, CD74 has since emerged as a central regulator of processes extending well beyond antigen presentation. More recent findings reveal that CD74, acting as a receptor of macrophage migration inhibitory factor, also participates in signaling pathways in non-immune cells, independent of its classical chaperone function. Proteolytic processing of CD74 can trigger signaling cascades that modulate gene expression, underscoring its multifunctionality. Dysregulation of CD74 cleavage and its interaction with proteases has been linked to diverse pathological conditions, including cancer and autoimmune diseases, where aberrant protease activity disrupts CD74 function and promotes disease progression. Full article

The major histocompatibility complex (MHC) class I and class II molecules (abbreviated as MHC-I and MHC-II, respectively) are specialized in antigen presentation. Unlike the T cell receptors (TCRs), which have great variability, the MHC-I and MHC-II molecules essentially have no variability at all. It is apparent that the MHC-I and MHC-II molecules per se do not have the built-in ability to distinguish the huge populations of self-peptides from antigenic non-self-peptides. At present, the precise mechanism underlying the selective presentation of antigenic peptides by both MHC-I and MHC-II molecules is unclear. For an MHC-II molecule to gain the ability to selectively present antigenic (mostly foreign) peptides, it is hypothesized herein that all naïve CD4⁺ T cells in the body will release extracellular vesicles (EVs), which are specially designed for antigen-presenting cells (APCs); these EVs contain mRNAs that will be delivered to APCs and translated into an intracellular version of the TCR proteins (iTCR^II), which will help select antigenic peptides for presentation by the MHC-II molecules. Similarly, it is hypothesized that the fully activated CD4⁺ T cells will also release EVs, and these EVs contain different mRNAs for another intracellular version of the TCR proteins (iTCR^I), which will help pathogen-infected somatic cells to select the antigenic peptides (mostly from invading pathogens) for presentation by the MHC-I molecules. Understandably, while the iTCR^II proteins will work closely with the MHC-II molecules in the exogenous endocytic pathway, the iTCR^I proteins will work closely with the MHC-I molecules in the endogenous pathway. In this paper, a few other related hypotheses are also proposed, which jointly offer a plausible mechanistic explanation for the selective presentation of antigenic peptides by both MHC-I and MHC-II molecules. While the proposed hypotheses are partly supported by some experimental observations, it is hoped that these hypotheses will promote discussion and experimental testing of the mechanisms underlying the complex process of selective antigen presentation. Full article

Streptococcus suis (S. suis) is an important zoonotic pathogen that causes severe disease in both humans and pigs, leading to substantial economic losses in the swine industry. Extracellular vesicles (EVs), as critical mediators of host–pathogen interactions, play key roles in bacterial virulence and disease progression. This study aimed to investigate the biological properties of S. suis EVs and elucidate their role in the bacterium’s pathogenesis. We isolated and characterized S. suis EVs, which were found to contain diverse protein molecules. EVs were efficiently internalized by mammalian cells, and concentrations below 50 μg/mL did not affect cell viability. Following uptake, EVs suppressed the production of key pro-inflammatory cytokines (TNF-α, IL-1β, and IL-8) by modulating macrophage metabolism. They also downregulated the expression of major histocompatibility complex class II (MHC-II) and adhesion molecules (VCAM-1 and ICAM-1) during subsequent infections, potentially impairing macrophage-mediated clearance. In addition, EVs served as vectors for efficient cargo delivery and facilitated S. suis adhesion to and invasion of endothelial cells. In infection models, EVs markedly enhanced lethality in Galleria mellonella larvae and promoted tissue colonization in murine models. These findings suggest that S. suis EVs are key mediators of host–pathogen interactions, contributing to colonization and disease pathogenesis. Moreover, they offer novel insights and potential strategies for the prevention and control of S. suis infections. Full article

Background/Objectives: Neuroinflammation, a hallmark of Alzheimer’s disease (AD), is characterized by elevated levels of inflammatory signaling molecules, including cytokines and eicosanoids, as well as increased microglial reactivity, and is augmented by gut microbiota dysbiosis via the gut–brain axis. We conducted a pilot experiment to elucidate the anti-inflammatory effects of dietary omega-3 polyunsaturated fatty acid (ω-3 PUFA) eicosapentaenoic acid (EPA) on the gut microbiota and neuroinflammation. Methods: Female APP/PS1 mice (TG) and non-transgenic littermates (WT), 13–14 months old, were fed a diet supplemented with 0.3% EPA or control chow for 3 weeks. The gut microbiota composition, hippocampal and plasma eicosanoids levels, platelet activation, and microglial phagocytosis, as well as the brain and retinal genes and protein expression, were analyzed. Results: EPA supplementation decreased the percentage of Bacteroidetes and increased bacteria of the phylum Firmicutes in APP/PS1 and WT mice. Inflammatory lipid mediators were elevated in the hippocampus of the TG mice, accompanied by a reduction in the endocannabinoid docosahexaenoyl ethanolamide (DHEA). Dietary EPA did not affect hippocampal lipid mediators, but reduced the levels of arachidonic-derived 5-HETE and N-arachidonoylethanolamine (AEA) in WT plasma. Moreover, EPA supplementation decreased major histocompatibility complex class II (MHCII) gene expression in the retina in both genotypes, and MHCII+ cells in the hippocampus of TG mice. Conclusions: This pilot study showed that short-term EPA supplementation shaped the gut microbiota by increasing butyrate-producing bacteria of the Firmicutes phylum and decreasing Gram-negative LPS-producing bacteria of the Bacteroidetes phylum, and downregulated the inflammatory microglial marker MHCII in two distinct regions of the central nervous system (CNS). Further investigation is needed to determine whether EPA-mediated effects on the microbiome and microglial MHCII have beneficial long-term effects on AD pathology and cognition. Full article

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by self-antibody production and widespread inflammation affecting various body tissues. This disease is driven by the breakdown of immune tolerance, which promotes the activation of autoreactive B and T cells. A key feature of SLE is dysregulation in antigen presentation, where antigen-presenting cells (APCs) play a central role in perpetuating immune responses. Dendritic cells (DCs) are highly specialized for antigen presentation among APCs. At the same time, myeloid-derived suppressor cells (MDSCs) can also express MHC-II molecules, although their role in SLE is less understood. Utilizing the SLE model, MRL/MpJ-Fas^lpr/J, we determined the presence of different phenotypes of DCs and MDSCs expressing MHC-II in secondary lymphoid organs, along with the gene expression of ICOSL, CD80 and CD86 in the spleen. Our study determined that the most abundant population of APCs in secondary lymphoid organs corresponds to cDC CD103⁻CD11b⁺ MHC-II⁺ throughout SLE development. Additionally, ICOSL expression increased over time, becoming more preponderant in week 16 in the SLE model, which could indicate that it is a crucial pathway for the development and progression of the pathology. In week 16, we observed a positive correlation between M-MDSC MHC-II and IFN-γ-producing CD4⁺ T cells. Full article

Notch signaling manipulates the function and phenotype of dendritic cells (DCs), as well as the interaction between DCs and CD4⁺ T cells. However, the role of Notch signaling in Helicobacter pylori (H. pylori) infection remains elusive. Murine bone marrow-derived dendritic cells (BMDCs) were pretreated in the absence or presence of Notch signaling inhibitor DAPT prior to H. pylori stimulation and the levels of Notch components, cytokines and surface markers as well as the differentiation of CD4⁺ T cells in co-culture were measured using quantitative real-time PCR (qRT-PCR), Western blot, enzyme-linked immunosorbent assay (ELISA) and flow cytometry. Compared with the control, the mRNA expression of all Notch receptors and Notch ligands Dll4 and Jagged1 was up-regulated in H. pylori-stimulated BMDCs. The blockade of Notch signaling by DAPT influenced the production of IL-1β and IL-10 in H. pylori-pulsed BMDCs, and reduced the expression of Notch1, Notch3, Notch4, Dll1, Dll3 and Jagged2. In addition, DAPT pretreatment decreased the expression of maturation markers CD80, CD83, CD86, and major histocompatibility complex class II (MHC-II) of BMDCs, and further skewed Th17/Treg balance toward Treg. Notch signaling regulates the function and phenotype of DCs, thus mediating the differentiation of CD4⁺ T cells during H. pylori infection. Full article

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease causing axonal degeneration and demyelination. Exercise in mice with active monophasic experimental autoimmune encephalomyelitis (EAE) attenuates disease severity associated with diverse impacts on T cell-mediated immunity. However, studies have so far focused on preventive approaches. In this study, we investigated the impact of endurance exercise on established EAE disease in a model of secondary progressive MS. When the exercise program on motorized running wheels was started at disease manifestation, the disease course was significantly ameliorated. This was associated with a significant decrease in B cell, dendritic cell, and neutrophil cell counts in the central nervous system (CNS). Furthermore, we observed an increased expression of major histocompatibility complex class II (MHC-II) as well as alterations in costimulatory molecule expression in CNS B cells and dendritic cells. In contrast, T cell responses were not altered in the CNS or periphery. Thus, exercise training is capable of attenuating the disease course even in established secondary progressive EAE, potentially via modulation of the innate immune compartment. Further studies are warranted to corroborate our findings and assess the potential of this lifestyle intervention as a complementary therapeutic strategy in secondary progressive MS patients. Full article

It has been shown that synovial fibroblasts (SF) play a key role in the initiation of inflammation and joint destruction, leading to arthritis progression. Fibroblasts may express major histocompatibility complex class II region (MHCII) molecules, and thus, they could be able to process and present antigens to immunocompetent cells. Here we examine whether different types of fibroblasts (synovial, dermal, and thymic murine fibroblasts, destructive LS48 fibroblasts, and noninvasive NIH/3T3 fibroblasts) may be involved in the initiation of rheumatoid arthritis (RA) pathogenesis and can process and present type II collagen (COL2)—an autoantigen associated with RA. Using a panel of MHCII/Aq-restricted T-cell hybridoma lines that specifically recognize an immunodominant COL2 epitope (COL2_259–273), we found that NIH/3T3 fibroblasts activate several T-cell clones that recognize the posttranslationally glycosylated or hydroxylated COL2_259–273 epitope. The HCQ.3 hybridoma, which is specific for the glycosylated immunodominant COL2 epitope 259–273 (Gal264), showed the strongest response. Interestingly, NIH/3T3 cells, but not destructive LS48 fibroblasts, synovial, dermal, or thymic fibroblasts, were able to stimulate the HCQ.3 hybridoma and other COL2-specific T-cell hybridomas. Our experiments revealed that NIH/3T3 fibroblasts are able to activate COL2-specific T-cell hybridomas even in the absence of COL2 or a posttranslationally modified COL2 peptide. The mechanism of this unusual activation is contact-dependent and involves the T-cell receptor (TCR) complex. Full article

The chytrid fungus Batrachochytrium dendrobatidis (Bd) is a major threat to amphibians, yet there are no reports of major disease impacts in East Asian frogs. Genetic variation of the major histocompatibility complex (MHC) has been associated with resistance to Bd in frogs from East Asia and worldwide. Using transcriptomic data collated from 11 Japanese frog species (one individual per species), we isolated MHC class I and IIb sequences and validated using molecular cloning. We then compared MHC from Japanese frogs and other species worldwide, with varying Bd susceptibility. Supertyping analysis, which groups MHC alleles based on physicochemical properties of peptide binding sites, identified that all examined East Asian frogs contained at least one MHC-IIb allele belonging to supertype ST-1. This indicates that, despite the large divergence times between some Japanese frogs (up to 145 million years), particular functional properties in the peptide binding sites of MHC-II are conserved among East Asian frogs. Furthermore, preliminary analysis using NetMHCIIpan-4.0, which predicts potential Bd-peptide binding ability, suggests that MHC-IIb ST-1 and ST-2 have higher overall peptide binding ability than other supertypes, irrespective of whether the peptides are derived from Bd, other fungi, or bacteria. Our findings suggest that MHC-IIb among East Asian frogs may have co-evolved under the same selective pressure. Given that Bd originated in this region, it may be a major driver of MHC evolution in East Asian frogs. Full article

Antigen presentation by major histocompatibility complex class II (MHC-II) molecules is crucial for eliciting an efficient immune response by CD4⁺ T cells and maintaining self-antigen tolerance. Some MHC-II alleles are known to be positively or negatively associated with the risk of the development of different autoimmune diseases (ADs), including those characterized by the emergence of autoreactive T cells. Apparently, the MHC-II presentation of self-antigens contributes to the autoimmune T cell response, initiated through a breakdown of central tolerance to self-antigens in the thymus. The appearance of autoreactive T cell might be the result of (i) the unusual interaction between T cell receptors (TCRs) and self-antigens presented on MHC-II; (ii) the posttranslational modifications (PTMs) of self-antigens; (iii) direct loading of the self-antigen to classical MHC-II without additional nonclassical MHC assistance; (iv) the proinflammatory environment effect on MHC-II expression and antigen presentation; and (v) molecular mimicry between foreign and self-antigens. The peculiarities of the processes involved in the MHC-II-mediated presentation may have crucial importance in the elucidation of the mechanisms of triggering and developing ADs as well as for clarification on the protective effect of MHC-II alleles that are negatively associated with ADs. Full article

Multiple vaccines were developed and administered to immunize people worldwide against SARS-CoV-2 infection. However, changes in platelet count following the course of vaccination have been reported by many studies, suggesting vaccine-induced thrombocytopenia. In this context, designing an effective targeted subunit vaccine with high specificity and efficiency for people with low platelet counts has become a challenge for researchers. Using the in silico-based approaches and methods, the present study explored the antigenic epitopes of the spike protein of SARS-CoV-2 involved in initial binding of the virus with the angiotensin converting enzyme-2 receptor (ACE-2) on the respiratory epithelial cells. The top ten major histocompatibility complex-I (MHC-I) and MHC-II restricted epitopes were found to have 95.26% and 99.99% HLA-class-I population coverage, respectively. Among the top ten promiscuous MHC-I restricted epitopes, ’FTISVTTEI’ had the highest global HLA population coverage of 53.24%, with an antigenic score of 0.85 and a docking score of −162.4 Kcal/mol. The epitope ‘KLNDLCFTNV’ had the best antigenic score of 2.69 and an HLA population coverage of 43.4% globally. The study predicted and documented the most suitable epitopes with the widest global HLA coverage for synthesis of an efficient peptide-based vaccine against the deadly COVID-19. Full article

The swift emergence of antibiotic resistance (AR) in bacterial pathogens to make themselves adaptable to changing environments has become an alarming health issue. To prevent AR infection, many ways can be accomplished such as by decreasing the misuse of antibiotics in human and animal medicine. Among these AR bacterial species, Plesiomonas shigelloides is one of the etiological agents of intestinal infection in humans. It is a gram-negative rod-shaped bacterium that is highly resistant to several classes of antibiotics, and no licensed vaccine against the aforementioned pathogen is available. Hence, substantial efforts are required to screen protective antigens from the pathogen whole genome that can be subjected easily to experimental evaluations. Here, we employed a reverse vaccinology (RV) approach to design a multi-antigenic epitopes based vaccine against P. shigelloides. The complete genomes of P. shigelloides were retrieved from the National Center for Biotechnological Information (NCBI) that on average consist of 5226 proteins. The complete proteomes were subjected to different subtractive proteomics filters, and in the results of that analysis, out of total proteins, 2399 were revealed as non-redundant and 2827 as redundant proteins. The non-redundant proteins were further checked for subcellular localization analysis, in which three were localized in the extracellular matrix, eight were outer membrane, and 13 were found in the periplasmic membrane. All surface localized proteins were found to be virulent. Out of a total of 24 virulent proteins, three proteins (flagellar hook protein (FlgE), hypothetical protein, and TonB-dependent hemoglobin/transferrin/lactoferrin family receptor protein) were considered as potential vaccine targets and subjected to epitopes prediction. The predicted epitopes were further examined for antigenicity, toxicity, and solubility. A total of 10 epitopes were selected (GFKESRAEF, VQVPTEAGQ, KINENGVVV, ENKALSQET, QGYASANDE, RLNPTDSRW, TLDYRLNPT, RVTKKQSDK, GEREGKNRP, RDKKTNQPL). The selected epitopes were linked with each other via specific GPGPG linkers in order to design a multi-epitopes vaccine construct, and linked with cholera toxin B subunit adjuvant to make the designed vaccine construct more efficient in terms of antigenicity. The 3D structure of the vaccine construct was modeled ab initio as no appropriate template was available. Furthermore, molecular docking was carried out to check the interaction affinity of the designed vaccine with major histocompatibility complex (MHC-)I (PDB ID: 1L1Y), MHC-II (1KG0), and toll-like receptor 4 ((TLR-4) (PDB: 4G8A). Molecular dynamic simulation was applied to evaluate the dynamic behavior of vaccine-receptor complexes. Lastly, the binding free energies of the vaccine with receptors were estimated by using MMPB/GBSA methods. All of the aforementioned analyses concluded that the designed vaccine molecule as a good candidate to be used in experimental studies to disclose its immune protective efficacy in animal models. Full article

Immunogenic cell death (ICD) in cancer represents a functionally unique therapeutic response that can induce tumor-targeting immune responses. ICD is characterized by the exposure and release of numerous damage-associated molecular patterns (DAMPs), which confer adjuvanticity to dying cancer cells. The spatiotemporally defined emission of DAMPs during ICD has been well described, whereas the epigenetic mechanisms that regulate ICD hallmarks have not yet been deeply elucidated. Here, we aimed to examine the involvement of miRNAs and their putative targets using well-established in vitro models of ICD. To this end, B cell lymphoma (Mino) and breast cancer (MDA-MB-231) cell lines were exposed to two different ICD inducers, the combination of retinoic acid (RA) and interferon-alpha (IFN-α) and doxorubicin, and to non ICD inducers such as gamma irradiation. Then, miRNA and mRNA profiles were studied by next generation sequencing. Co-expression analysis identified 16 miRNAs differentially modulated in cells undergoing ICD. Integrated miRNA-mRNA functional analysis revealed candidate miRNAs, mRNAs, and modulated pathways associated with Immune System Process (GO Term). Specifically, ICD induced a distinctive transcriptional signature hallmarked by regulation of antigen presentation, a crucial step for proper activation of immune system antitumor response. Interestingly, the major histocompatibility complex class I (MHC-I) pathway was upregulated whereas class II (MHC-II) was downregulated. Analysis of MHC-II associated transcripts and HLA-DR surface expression confirmed inhibition of this pathway by ICD on lymphoma cells. miR-4284 and miR-212-3p were the strongest miRNAs upregulated by ICD associated with this event and miR-212-3p overexpression was able to downregulate surface expression of HLA-DR. It is well known that MHC-II expression on tumor cells facilitates the recruitment of CD4+ T cells. However, the interaction between tumor MHC-II and inhibitory coreceptors on tumor-associated lymphocytes could provide an immunosuppressive signal that directly represses effector cytotoxic activity. In this context, MHC-II downregulation by ICD could enhance antitumor immunity. Overall, we found that the miRNA profile was significantly altered during ICD. Several miRNAs are predicted to be involved in the regulation of MHC-I and II pathways, whose implication in ICD is demonstrated herein for the first time, which could eventually modulate tumor recognition and attack by the immune system. Full article