Search Results (376)

The dysregulation of immune homeostasis and the persistence of chronic, low-grade inflammation represent core pathophysiological drivers governing the onset and progression of metabolic and cardiovascular disorders. Myeloid-derived suppressor cells (MDSCs) comprise a highly heterogeneous population of immature myeloid cells that are rapidly mobilized from the bone marrow in response to biological stressors, such as sustained tissue injury and chronic inflammatory signaling. Historically evaluated within oncology and infectious disease frameworks, accumulating evidence highlights the pivotal, context-dependent roles of MDSCs in cardiometabolic environments. In conditions of obesity and type 2 diabetes (T2D), MDSCs undergo substantial expansion and accumulation within peripheral tissues, including adipose tissue and the liver. Functionally, MDSCs act as dynamic immunoregulators that can either buffer metabolic inflammation, via the secretion of interleukin-10 (IL-10), transforming growth factor-beta (TGF-β), and nitric oxide (NO) or, conversely, reflect and exacerbate disease progression depending on specific cellular subsets, glycemic control, and tissue localization. Within the vascular system, specific monocytic MDSC subsets demonstrate significant atheroprotective and cardioprotective capabilities by dampening Th1/Th17-mediated arterial wall inflammation, stabilizing atherosclerotic plaques, and preserving cardiac structural architecture during heart failure. However, phenotypic and functional heterogeneity poses a critical clinical challenge, as certain persistent or altered subsets correlate with heightened cardiovascular risk and adverse cerebrovascular outcomes. This review delivers a comprehensive synthesis of contemporary insights into MDSC biology at the intersection of obesity-associated diabetes and cardiovascular disease, characterizing their dualistic mechanisms, distinguishing preclinical causal mechanisms from human observational data. Moreover, we have established a comprehensive framework to reconcile the conflicting protective versus detrimental effects of MDSCs. And finally, we have also evaluated their potential clinical utility as candidate biomarkers, delineating the safety imperatives essential for translating MDSC-targeted therapeutic interventions into clinical practice. Full article

Myeloid-derived suppressor cells (MDSCs) are heterogeneous cell populations that promote tumor development by inhibiting innate and adaptive immunity. Under physiological conditions, neutrophils have a short survival time in vivo. However, G-MDSCs accumulate abnormally in most tumor hosts, and the mechanisms underlying G-MDSC persistence remain to be clarified. This study utilized flow cytometric analysis and in vivo assays to elucidate these mechanisms. It was observed that the apoptosis of G-MDSCs in the peripheral blood of mice was reduced under tumor conditions, whereas an increase in granulocyte colony-stimulating factor (G-CSF) promoted the survival of G-MDSCs. Furthermore, G-CSF reduced the apoptosis of G-MDSCs by activating the Erk/CREB pathway. Thus, inhibition of G-CSF/Erk/CREB signaling may promote the apoptosis of G-MDSCs and shorten their persistence under tumor conditions, as well as attenuate tumor progression. Full article

Colorectal cancer, especially the microsatellite-stable subtype, which accounts for 85% to 95% of cases, resists immune checkpoint inhibitors largely due to metabolic reprogramming in the tumor microenvironment. Lactate has evolved from a waste product into a central immunosuppressive regulator. Oncogenic KRAS and BRAF mutations drive aerobic glycolysis, causing glucose deprivation and massive lactate accumulation in the tumor microenvironment. Lactate suppresses immunity through three parallel mechanisms. It signals via GPR81 to recruit polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and inhibit T-cell function. It contributes to histone H3K18 lactylation, which silences effector genes including IFN-γ and GZMB while upregulating PD-L1 expression. It also acidifies the microenvironment to pH 6.0–6.5, directly impairing NK and T-cell activity. Concurrent lipid abundance stabilizes the MCT4 lactate exporter, forming a bidirectional feed-forward loop that amplifies lactate effects. Spatial metabolic heterogeneity creates distinct immune battlefields, with a supportive ‘metabolic oasis’—a concept proposed in this review—at the invasive front and a deeply immunosuppressive core. Thus, lactate acts as an epigenetic and signaling hub that bridges oncogenic mutations, metabolic competition and immune evasion. Targeting lactate metabolism through LDHA or MCT4 inhibition, modulation of histone lactylation, or disruption of lactate-lipid crosstalk, when combined with classical immune checkpoint blockade and guided by spatial biomarkers, offers a promising strategy to overcome immunotherapy resistance in this challenging subtype. Full article

Background/Objectives: Human papillomavirus (HPV)-associated cancers remain a major global health burden, and no therapeutic cancer vaccine has yet been approved. Oncoprotein E7 plays a key role in tumor initiation and progression and has been identified as a potential target. Here, we aim to improve the efficacy and durability of an outer membrane vesicle (OMV)-based E7-targeted vaccine, SOMV-9RE7, through alb-Flt3L combination therapy. Methods: The antitumor efficacy and durability of the combination therapy were evaluated in low-burden and high-burden HPV-positive TC-1 tumor-bearing mouse models. Systemic and local immune responses were investigated by flow cytometry. Results: Combination with alb-Flt3L improved the tumor control and prolonged the therapeutic durability of SOMV-9RE7 compared with monotherapy groups, with more than half of the treated mice surviving beyond 60 days. This combination strategy enhanced E7-specific CD8⁺ T cell immunity in peripheral blood and the spleen, reduced myeloid-derived suppressor cell (MDSC)-mediated immunosuppression, promoted splenic T cell memory formation, and reshaped the tumor microenvironment. Conclusions: Combining vaccine SOMV-9RE7 with alb-Flt3L improves antitumor efficacy and durability. This therapeutic benefit is associated with both systemic and local immune remodeling, supporting the combination therapy as a promising strategy for therapeutic cancer vaccines. Full article

Human secreted phospholipase A₂ group IIA (hGIIA) is a Ca²⁺-dependent extracellular enzyme that supports host defense and amplifies inflammation through lipid mediator generation and receptor-linked signaling. In prostate cancer (PCa), hGIIA is commonly elevated compared with benign tissue and can persist after androgen deprivation, implicating it in tumor progression. PCa is typically an immunologically “cold” disease sustained by an immunosuppressive tumor microenvironment enriched in regulatory T cells ( T_reg), myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), and pro-tumor stromal cells, alongside hypoxia and metabolic rewiring. Because hGIIA is released by innate immune cells and is inducible in macrophages, it is well positioned to strengthen inflammatory lipid networks and promote immune dysfunction within the prostate tumor microenvironment. Here, we review the PCa microenvironment and evaluate evidence linking hGIIA to tumor–stroma crosstalk, angiogenic programming, and therapy resistance, highlighting major knowledge gaps in prostate-focused immune studies. Full article

Background: Seasonal influenza vaccination shows highly variable effectiveness across individuals, particularly in older adults, in whom age-related immune decline compromises protective responses. Methods: This study evaluated immune responses to the 2019/2020 quadrivalent influenza vaccine in 75 individuals aged 25–89 years. Influenza-specific antibody titers and virus-neutralizing activity were measured before and four weeks after vaccination, and participants were stratified as high or low responders. Results: We observed that older individuals exhibited increased frequencies of myeloid-derived suppressor cells (MDSCs) and activated regulatory T cells (Treg) expressing HLA-DR and CD38, consistent with enhanced immunosuppressive activity. Importantly, higher levels of these immunoregulatory populations correlated with poor vaccine responsiveness in both adult and older participants. Additionally, circulating T follicular regulatory (Tfr) cells were elevated in older participants and in low responders, whereas T follicular helper (Tfh) cells remained unchanged, resulting in an increased Tfr/Tfh ratio associated with impaired antibody production. However, when adjusting for possible confounders, most immunoregulatory subsets did not remain independently associated with responder status, except CD38⁺ Treg cells. Conclusions: These findings suggest that immunoregulatory networks, while essential for controlling chronic inflammation during aging, may limit vaccine-induced immunity. Identifying biomarkers such as MDSC frequency, activated Treg phenotype, and Tfr/Tfh balance may contribute to the identification of individuals with different levels of vaccine responsiveness and could help inform future personalized vaccination strategies. Full article

Background: Immune-checkpoint blockade (ICB) is a recent addition to the treatment options for breast cancer, especially the triple-negative (TNBC) subset. Inhibiting immunosuppressive factors in the tumor microenvironment (TME) and preventing or reversing T cell exhaustion may increase the likelihood of a response to ICB. We have shown that decitabine and guadecitabine, DNA methyltransferase inhibitors (DNMTi), prevent the systemic and TME accumulation of myeloid-derived suppressor cells (MDSCs), which are immunosuppressive. Results: Here, we show that adding DNMTi to the neoadjuvant + adjuvant ICB-based treatment of ICB-resistant 4T1 and E0771 murine tumors in Balb/C and C57Bl/6 mice, respectively, effectively reduced the tumor burden, with 52% of 4T1 tumors completely regressing across several studies. DNMTi-based therapy overcame ICB resistance (ICBR) in a selected subline of E0771, and treated tumors showed a reduction in MDSCs. We also show that, in E0771, DNMTi can overcome ICBR to multiple checkpoint inhibitors, and in 4T1, it can modulate anti-tumor immunity by enhancing central memory T cell (Tcm) formation and reducing T cell exhaustion. Conclusion: These pre-clinical findings support the further investigation of incorporating DNMTi as a new immunotherapy modality for TNBC. Full article

Lung cancer ranks first in both incidence and mortality among all malignancies, and tumor microenvironment (TME)-induced CD8⁺ T cell exhaustion is a critical factor driving immune evasion and compromising the efficacy of immunotherapy. MicroRNAs (miRNAs), as key post-transcriptional regulators, shuttle between lung cancer cells and CD8⁺ T cells via extracellular vesicles (EVs), serving as critical communication hubs that reshape the TME. This review systematically synthesizes recent literature to summarize the regulatory patterns of miRNAs on functions of lung cancer cells and CD8⁺ T cells, and dissect the molecular mechanisms underlying miRNA-mediated bidirectional crosstalk between these two cell types. This review focuses on the dual-pronged immune evasion strategy employed by lung cancer cells to counteract CD8⁺ T cells. On the one hand, lung cancer cells aberrantly express endogenous miRNAs, such as miR-20a, miR-149-5p, and miR-326, to remodel their surface ligands and establish immune camouflage. On the other hand, they actively secrete EVs enriched in specific miRNAs, including miR-7108-3p, miR-651-5p, and miR-24-3p, which directly suppress CD8⁺ T cell function. Furthermore, lung cancer cells secrete additional miRNAs, notably miR-6794-5p, miR-708-5p, and miR-1234-3p, to reprogram other TME components, namely tumor-associated macrophages (TAMs), natural killer (NK) cells, and myeloid-derived suppressor cells (MDSCs). These reprogrammed cells, in turn, indirectly attenuate CD8⁺ T cells through a relay-like mechanism via immunosuppressive cytokines or surface checkpoint molecules produced by these cells. In addition, competing endogenous RNA (ceRNA) networks formed by long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) in lung cancer cells regulate miRNA activity at multiple levels, further impairing the immune effector functions of CD8⁺ T cells. Conversely, activated CD8⁺ T cells also secrete miRNA-containing EVs, which deliver these miRNAs to tumor cells, thereby inhibiting tumor progression. Elucidation of this miRNA-based bidirectional communication network will not only advance our understanding of immune evasion mechanisms in lung cancer but also provide novel insights into cell-free immunotherapeutic approaches based on CD8⁺ T cell-derived vesicles. Full article

Background: Chronic psychological stress drives metastasis in triple-negative breast cancer (TNBC), yet the underlying mechanisms remain poorly understood and effective interventions are lacking. Stress-induced expansion of myeloid-derived suppressor cells (MDSCs) and subsequent immune remodeling play critical roles, with aberrant myeloid differentiation of hematopoietic stem and progenitor cells (HSPCs) serving as a major source of MDSCs. This study investigates whether epicatechin gallate (ECG) suppresses stress-driven TNBC growth and lung metastasis by regulating HSPC myeloid differentiation. Methods: A mouse model of chronic unpredictable mild stress (CUMS) followed by 4T1 tumor implantation was used to evaluate the anti-tumor effects of ECG. CETSA-WB, molecular docking, HSPC differentiation assays, and MDSC functional validation assays, along with immunohistochemistry, immunofluorescence, and flow cytometry, were performed to elucidate how ECG modulates glucocorticoid (GC)/glucocorticoid receptor (GR) signaling and HSPC differentiation. Results: ECG dose-dependently alleviated depressive-like behaviors, reduced serum corticosterone (Cort), and inhibited tumor growth and lung metastasis. Notably, ECG decreased lung metastatic foci by 76.9% relative to the CUMS group. Mechanistically, chronic stress activated GR and induced its nuclear translocation in HSPCs, promoting aberrant HSPC-to-MDSC differentiation. ECG directly bound GR, blocked its nuclear translocation, and suppressed the myeloid differentiation of HSPCs into MDSCs, which was accompanied by downregulation of S100A8/A9, fibronectin, and MMP-2, as well as increased CD8⁺ T cell infiltration. Supernatants from ECG-pretreated and differentiated HSPCs reversed Cort-induced epithelial–mesenchymal transition (EMT) in 4T1 cells. Conclusions: ECG acts as a natural GR signaling blocker that directly targets GR to block chronic stress-driven abnormal myeloid differentiation of HSPCs, thereby remodeling the pulmonary immune microenvironment, suppressing EMT, and reducing breast cancer lung metastasis. These findings identify ECG as a promising GR signaling blocker and a potential adjuvant therapy for cancer patients under high-stress conditions. Full article

Global elimination of hepatitis C virus (HCV) infection requires not only direct-acting antivirals (DAAs) but also the development of a highly effective prophylactic and/or therapeutic vaccine. Background/Objectives: Our aim was to optimize the composition of the candidate vaccine against HCV by combining recombinant non-structural proteins and a DNA construct with a complex adjuvant. Methods: C57BL/6 and DBA/2J mice were immunized three times at 2-week intervals using different schemes. The viral antigens consisted of a mixture of NS3, NS5A, and NS5B proteins and/or recombinant DNA expressing NS3-NS5B polyprotein. As adjuvants, a complex adjuvant, a mixture of Polymuramil^® and Pyrogenalum^® (NOD1/NOD2 and TLR-4 agonists), or a CpG ODN adjuvant (TLR-9 agonist) were used. Results: The most efficient regimen was three subcutaneous administrations of the combined DNA, recombinant protein components, and a new complex adjuvant. This scheme elicited a robust immune response, characterized by high antibody titers, enhanced antigen-specific lymphocyte proliferation, and significant interferon-gamma (IFN-γ) secretion in both mouse lines. Furthermore, the complex adjuvant outperformed CpG ODN in stimulating both humoral and cellular immunity against the HCV antigens. The vaccine composition stimulated the formation of CD4⁺ memory T cells and decreased the relative frequences of suppressive Treg and MDSCs. Conclusions: The presented candidate vaccine induces a strong immune response to HCV proteins. The next step would be to validate the protective effect in cell culture and animal models. This would one the path to preclinical studies of this vaccine composition. Full article

Persistent infection with high-risk human papillomavirus (HPV), particularly HPV16, is a major driver of HPV-associated cancers; however, strategies for treating established HPV-induced tumors remain scarce. Here, we developed a DNA-based vaccine linking the SARS-CoV-2 spike (S) protein with an HPV16 E7 epitope (aa 49-57) to simultaneously induce antiviral humoral immunity and antitumor cellular responses. We generated 2 constructs, S-E7 and S-RE7, with the latter incorporating a furin cleavage site (R) to enhance antigen processing. In vitro, S-RE7 significantly enhanced E7-specific CD8⁺ T cell activation compared to S-E7, highlighting the importance of the furin sequence. In vivo, both S-linked vaccines elicited robust E7-specific CD8⁺ T cell responses and provided complete protection against TC-1 tumor challenge in a prophylactic murine model, with long-lasting immunity upon tumor rechallenge. In therapeutic settings, vaccination with S-E7 or S-RE7 significantly suppressed tumor growth, extended survival, and reduced circulating myeloid-derived suppressor cells (MDSCs), indicating alleviation of systemic immunosuppression. Notably, S-RE7 demonstrated faster antitumor effects overall in early tumor progression. In addition to cellular immunity, both constructs induced high levels of anti-spike antibodies, with S-RE7 eliciting approximately fourfold higher responses than S-E7. Furthermore, S-RE7 effectively boosted pre-existing anti-spike immunity in mice that were previously vaccinated. This “two-in-one” strategy represents a promising and versatile platform for the prevention and treatment of HPV-associated cancers while maintaining preparedness against potential SARS-CoV-2. Full article

Glutathione peroxidase 4 (GPX4) is canonically viewed as the primary suppressor of ferroptosis, yet its role in the tumor microenvironment (TME) extends far beyond antioxidant catalysis to encompass immuno-metabolic regulation. In this review, we synthesize recent advances in enzymology, immunology, and cancer metabolism to propose a “lipid peroxidation threshold” framework, wherein GPX4 sets cell-type-specific thresholds that determine susceptibility to ferroptosis across tumor cells, CD8⁺ T cells, dendritic cells (DCs), and myeloid populations. We discuss how these thresholds are dynamically adjusted by post-translational modifications, nutrient competition and intercellular feedback loops, resulting in significant spatial heterogeneity between the tumor core and the tumor invasive front. There is a current selectivity paradox in GPX4 inhibitors, as well as resistance through nuclear factor erythroid 2-related factor 2 (Nrf2) and ferroptosis suppressor protein 1 (FSP1) that restricts the efficacy of GPX4 inhibitors as monotherapy. We focus on rational combination approaches: GPX4 modulation with immune checkpoint blockade (ICB), chemotherapy, and targeting myeloid-derived suppressor cells (MDSCs); and the pressing need for predictive biomarkers and single-cell spatial profiling. We conclude that successful clinical translation requires moving beyond indiscriminate GPX4 inhibition toward precision “threshold engineering” that selectively lowers tumor lipid peroxidation thresholds while sparing immune cells. Full article

Chemotherapy resistance in triple-negative breast cancer (TNBC) remains a critical clinical challenge, with a substantial proportion of patients failing to achieve pathological complete response following neoadjuvant chemotherapy (NAC). Using an integrative single-cell RNA sequencing (scRNA-seq), bulk transcriptomic, and spatial proteomic framework, we aimed to identify the malignant epithelial subset driving this resistance and the intercellular signaling axes through which it reprograms the tumor microenvironment (TME). scRNA-seq analysis of NAC-treated breast tumors revealed a Fatty Acid–EMT co-expressing epithelial subset (FA-EMT) that is selectively enriched in the chemotherapy-resistant residuum. Critically, FA-EMT co-expression—rather than either program individually—most powerfully predicted chemotherapy resistance and reduced overall survival across two independent bulk transcriptomic cohorts comprising 277 TNBC patients (p < 0.001). CellChat ligand–receptor analysis established FA-EMT cells as the dominant TME signaling hub, deploying MDK–NCL and MIF–CD74–CXCR4 axes to simultaneously suppress adaptive and innate anti-tumor immunity via T-cell exhaustion, Treg activation, and the expansion of myeloid-derived suppressor cells. Spatial CyCIF validation in a published paclitaxel-resistant TNBC mouse model (n = 69 cores) confirmed significant Metabolic-EMT enrichment in resistant tumor cores (p = 0.0085) with physical co-localization with immunosuppressive MDSC and Treg populations. These findings establish the FA-EMT subset as a key cellular driver of treatment failure in TNBC and nominate MDK–NCL and MIF–CD74–CXCR4 as mechanistically grounded therapeutic targets with the potential to dismantle the FA-EMT-driven immunosuppressive niche and sensitize chemotherapy-resistant TNBC to cytotoxic treatment. Full article

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that accumulate in cancer and represent one of the major drivers of tumor-associated immunosuppression. MDSCs actively contribute to tumor progression by inhibiting both innate and adaptive immune responses, promoting angiogenesis, metastatic dissemination, and resistance to immunotherapy. Two major subsets have been identified, polymorphonuclear (PMN-) and monocytic (Mo-) MDSCs, each characterized by distinct phenotypic, metabolic, and suppressive properties. Within the tumor microenvironment (TME), MDSCs establish a complex network of interactions with T-, B-, NK-cells, dendritic cells, and macrophages, thereby orchestrating immune escape and tumor persistence. Recent evidence highlights the pivotal role of metabolic rewiring in regulating MDSC survival and suppressive activity. Enhanced aerobic glycolysis, fatty acid oxidation, amino acid depletion, reactive oxygen species (ROS) production, and adenosine metabolism collectively sustain MDSC-mediated immune dysfunction and shape the immunosuppressive TME. In particular, the crosstalk between PMN-MDSCs and NK cells has emerged as a critical mechanism of tumor immune evasion, leading to impaired NK cell cytotoxicity, altered activating receptor expression, and defective cytokine production. In this review, we summarize the current knowledge on the phenotypic and functional heterogeneity of MDSCs, their metabolic adaptations, and their interactions with immune effector populations in cancer. Furthermore, we discuss emerging therapeutic strategies aimed at targeting MDSC recruitment, differentiation, metabolic pathways, and suppressive functions. Understanding the molecular and metabolic mechanisms governing MDSC biology may provide novel opportunities to overcome tumor-induced immunosuppression and improve the efficacy of current cancer immunotherapies. Full article

Colorectal cancer (CRC) is a leading cause of cancer death worldwide, mainly due to metastasis. Circulating tumor cells (CTCs) act as the biological “seeds” of dissemination, traveling through the bloodstream to colonize distant organs. However, the blood is a hostile environment where CTCs must constantly face immune pressure. This review explores the bidirectional interactions between CTCs and immune cells in CRC, asking whether CTCs are merely vulnerable targets of immunosurveillance or can exploit the immune system for survival and metastasis. We dissect intrinsic and extrinsic immune evasion mechanisms, including MHC-I modulation, immune checkpoint expression (PD-L1, CD47, FasL), platelet cloaking, and neutrophil extracellular traps (NETs). Furthermore, we examine how CTCs form heterotypic clusters with monocytes, neutrophils, and lymphocytes, creating pro-metastatic niches and promoting phenotypic plasticity. The impact of CTCs on systemic immunity, including reprogramming of NK cells, T lymphocytes, and myeloid-derived suppressor cells (MDSCs), is discussed. Importantly, we highlight the emerging role of CTCs as dynamic biomarkers for immunotherapy, focusing on the predictive value of PD-L1+ CTCs and the potential of CTC-derived neoantigens for personalized vaccination. Despite progress, challenges remain in standardization, detection sensitivity, and clinical validation. Understanding the equilibrium between immune elimination and evasion by CTCs is crucial to develop novel interventions that interrupt the metastatic dialog and improve outcomes for CRC patients. Full article