Search Results (413)

Toll-like receptor 7 (TLR7) agonism offers a promising avenue for antiviral intervention. This study characterizes AXC-715, a novel small-molecule agonist that selectively targets TLR7 to elicit broad-spectrum antiviral effects. Structural analysis of the AXC-715–hTLR7 complex (PDB ID: 5GMH) elucidates the molecular basis of receptor activation. AXC-715 occupies the interface of TLR7 monomers, establishing critical hydrogen bonds with D555 and T586, alongside π-π and π-alkyl interactions with F408, V381, and L557. These interactions effectively promote and stabilize the active TLR7 dimeric conformation. Functionally, AXC-715 activates NF-κB signaling in a P65-dependent manner without inducing cytotoxicity in PK-15 or THP-1 cells. In vitro assays demonstrated that AXC-715 potently inhibits the replication of both pseudorabies virus (PRV) and vesicular stomatitis virus (VSV) by specifically impairing viral replication, distinct from adsorption, entry, assembly, or release processes. The antiviral effect was abolished in TLR7-knockout PK-15 cells, confirming the strict dependence of AXC-715 on on-target TLR7 signaling. These findings highlight AXC-715 as a potent TLR7 agonist that stabilizes receptor dimerization to inhibit viral replication, providing a valuable framework for developing TLR7-based antiviral therapeutics. Full article

Although immunotherapy has shown great promise in treating various types of cancer, advanced tumors are often refractory due to a highly immunosuppressive tumor microenvironment (TME). We previously engineered a cancer therapeutic vaccine platform, µGCVax, by co-loading tumor antigen peptides, STING and TLR9 agonists into porous silicon microparticles. While effective in models with lower disease burden, its efficacy against advanced colorectal cancer (CRC) was less promising due to the accumulation of myeloid-derived suppressor cells (MDSCs) in TMEs. In this study, we investigated whether µGCVax-based immunotherapy in advanced CRCs could be potentiated via regulating MDSCs to reprogram the TME. In an advanced CT26 murine CRC model, we assessed µGCVax in combination with oxaliplatin, a standard CRC chemotherapeutic with established immunomodulatory effects. We demonstrated that oxaliplatin was preferentially taken up by monocytic MDSCs (M-MDSCs) and effectively reduced their abundance in the bone marrow, blood, spleen, and tumor. Relief of this immunosuppressive TME increased intratumoral infiltration of antigen-specific CD8⁺ T cells. Ultimately, the combination of oxaliplatin with µGCVax induced robust regression of established CRC tumors. These findings highlight that oxaliplatin synergizes with µGCVax by overcoming MDSC-mediated immunosuppression and enhancing antitumor immunity, representing a promising chemo-immunotherapy strategy for advanced CRC. Full article

Aim: Sepsis-associated acute kidney injury (SA-AKI) remains a major cause of mortality, driven by inflammation and oxidative stress. Pioglitazone, a PPAR-γ agonist, has demonstrated anti-inflammatory and antioxidant effects beyond glycemic control. This study evaluated its renoprotective efficacy in a rat model of sepsis induced by cecal ligation and puncture (CLP). Methods: Thirty-six female Wistar rats were divided into Control, CLP + Saline, and CLP + Pioglitazone (10 mg/kg/day) groups. Survival was analyzed for 5 days. Renal function (BUN, creatinine, NGAL), oxidative stress (MDA), antioxidant signaling (NRF2), and inflammatory mediators (TNF-α, IL-6, HMGB1, TLR-4, NF-κB) were quantified by ELISA. Tubular epithelial necrosis, luminal debris, dilatation, hemorrhage, and inflammation were semi-quantitatively scored. Results: CLP caused marked renal dysfunction with elevated BUN, creatinine, and NGAL (p all <0.001 vs. Control). Pioglitazone significantly reduced these markers (p < 0.001 vs. CLP + Saline) and improved survival. Plasma MDA levels increased and renal Nrf2 levels decreased following CLP induction (both p < 0.001 vs. Control), whereas pioglitazone treatment significantly reduced MDA levels and increased NRF2 expression (p = 0.002 and p < 0.001 vs. CLP + Saline, respectively). Inflammatory mediators were markedly increased in sepsis (TNF-α, IL-6, HMGB1, TLR-4, and NF-κB; all p < 0.001 vs. Control) and significantly downregulated by pioglitazone (p < 0.01, p < 0.001, p < 0.001, p < 0.01, p < 0.01 vs. CLP + Saline, respectively). Histopathological injury was pronounced in septic rats (all p < 0.01 vs. Control) but was markedly ameliorated by pioglitazone p < 0.05, indicating substantial structural recovery. Conclusions: Pioglitazone markedly ameliorates CLP-induced SA-AKI by suppressing TLR-4/NF-κB/TNF-α signaling and oxidative stress, improving renal structure, function, and survival. These findings support its potential repurposing as a therapeutic adjunct in sepsis management. Full article

The immune system maintains homeostasis through coordinated innate and adaptive responses, and its imbalance increases disease susceptibility. The immunomodulatory effects of 6-methoxykaempferol (6MK), a methoxylated flavonoid found in sweet cherries, were studied in a mouse model of cyclophosphamide (CPA)-induced immunosuppression. The expression of key signaling proteins in the NF-κB and MAPK pathways was studied to explore the underlying molecular mechanisms. The Toll-like receptor-4/myeloid differentiation factor-2 receptor complex (TLR4/MD2), which can stimulate the immune response by activating these pathways, was used to study possible interactions with 6MK using docking analysis. 6MK administration significantly restored immune organ integrity (spleen up to 15.1% and thymus up to 16.8%), enhanced NK cell function (up to 43.8%), promoted T (up to 24.5%) and B cell proliferation (up to 26.4%), increased pro- and anti-inflammatory cytokine (IL-1β, IL-6, TNF-α, IL-4, IL-10, and TGF-β) levels, and elevated NO (up to 25.6%) and immunoglobulin (IgG, IgA, and IgM) concentrations. Additionally, 6MK upregulated antioxidant enzymes (CAT, HO-1, and SOD) and reactivated suppressed NF-κB and MAPK pathways. The docking-supported hypothesis, based on putative interactions and the estimated free energy of binding, suggests that 6MK possesses agonistic potential for the TLR4/MD2. Changes in the gut microbiome due to 6MK treatment, such as an increase in alpha diversity, abundance of Dorea longicatena, and the upregulation of formaldehyde-consuming pathways, may also contribute to immune enhancement. These findings show that 6MK may alleviate immunosuppression, suggesting its potential for future studies targeting immune-related diseases and conditions. Full article

Polymer nanoparticles have been widely studied for tumor treatment due to their excellent biocompatibility, structural diversity, and multi-functionality. Among their various applications, combining polymer-based photosensitizers with photodynamic therapy (PDT) and immunotherapy has emerged as a promising strategy for treating solid tumors. This combination not only enhances local tumor ablation but also activates systemic antitumor immune responses. Polymer Nanoparticles, with their unique photodynamic properties and ability to integrate multiple therapeutic modalities, offer a powerful platform for photo-immunotherapy. This review systematically discusses recent advances in the design of polymer Nanoparticles and their synergistic mechanisms when combined with immunomodulatory agents such as Toll-like receptor (TLR) agonists, STING agonists, and immune checkpoint inhibitors (ICBs). Moreover, we highlight challenges faced in clinical translation and outline future perspectives for the development of these combination therapies. Full article

Background/Objectives: Tuberculosis (TB) remains a major global health challenge, and the Bacillus Calmette–Guérin (BCG) vaccine has limited efficacy against adult pulmonary disease. Protein subunit vaccines are a promising alternative but require strong adjuvants to induce cell-mediated immunity. Synthetic agonists targeting toll-like receptor 4 (TLR4) and stimulators of interferon genes (STINGs) have emerged as effective immunostimulants. Therefore, we aimed to evaluate the immunogenicity and protective efficacy of Ag85B-based subunit vaccines formulated with synthetic TLR4 and STING agonists in a BCG-boosted mouse model. Methods: Three synthetic adjuvants—QTP709-1, QTP709-3, and QTP701—were formulated as oil-in-water emulsions containing distinct surfactant and immunostimulant components. The potential of vaccine formulations to activate dendritic cells (DCs) and elicit Ag85B-specific immune responses, including IgG subclass levels, interferon-γ (IFN-γ) enzyme-linked immunosorbent spots, and polyfunctional T-cell responses, was assessed by flow cytometry. Protective efficacy was evaluated based on pulmonary bacterial burden and histopathology following Mycobacterium tuberculosis (M. tb) Erdman challenge. Results: All formulations promoted DC maturation and enhanced antigen-specific immune responses. Each adjuvant elicited strong Ag85B-specific humoral immunity, increased IFN-γ secretion, and polyfunctional CD4⁺ and CD8⁺ T cells co-producing IFN-γ, TNF-α, and interleukin-2. Among them, QTP709-1 was associated with increased levels of chemokine receptor 5-associated chemokines and showed a trend toward reduced lung bacterial burden and histopathological inflammation following M. tb challenge. Conclusions: Synthetic TLR4 and STING agonists were associated with enhanced immunogenicity of TB subunit vaccines and showed evidence of protective potential, with TLR4-based formulations exhibiting more pronounced immunological responses. QTP709-1 exhibited strong immunostimulatory and protective effects, supporting its potential as a candidate adjuvant for next-generation TB vaccines. Full article

Background/Objectives: Brachytherapy (BT) is a local radiation treatment method for solid tumors. A single 10 Gy high–dose–rate (HDR) BT acts as an “in situ” vaccination. Tumor microenvironment (TME)–dependent radio–resistance mechanisms, such as increasing immunosuppression and hypoxia, lead to tumor recurrence after radiotherapy. Our study aimed to determine whether adding imiquimod (IMQ) to anticancer therapy would overcome TME–mediated mechanisms of radiotherapy resistance. IMQ, a toll–like receptor 7 (TLR7) agonist, acts as an immunostimulant and a vascular normalizing agent. Methods: Mice with well–developed tumors were treated with IMQ at a vascular–normalized dose of 50 μg, followed 5 days later by a single 10 Gy HDR BT. The dose coverage was planned using Discovery RT computed tomography CT scans. Irradiation was performed with a high–dose–rate afterloader equipped with an iridium–192 radioactive source. Results: In mice treated with a combination of IMQ and BT, we observed significant inhibition of melanoma tumor growth. We also noticed an effective therapeutic effect in mice with breast cancer, resulting in significantly prolonged survival and complete tumor regression in 20% of treated mice. In the blood of treated mice, we observed leukopenia with eosinophilia. In tumors, there was enhanced infiltration by cytotoxic CD8⁺ T lymphocytes. The depletion of CD8⁺ T cells completely abolished the effect of the combined therapy. Conclusions: The combination of IMQ with HDR brachytherapy induces a synergistic effect, improving the therapeutic antitumor effect of brachytherapy. Our data indicate that it is reasonable to use drugs that prevent changes in the TME in combination with radiotherapy. Full article

Background/Objectives: Vaccines targeting melanoma antigens can elicit CD8⁺ T cell responses, but a growing body of work suggests CD4⁺ T cells also play a role in tumor control. Induction of CD4⁺ cells may also support B cells in producing tumor antigen-specific antibodies (Abs). We investigated Abs induced by vaccination with a cocktail of six class II MHC-restricted melanoma peptides (6MHP) and the effect of adjuvant type on Ab isotypes. We hypothesized that the vaccines would induce Abs that respond to different epitopes on individual peptides and that IgG isotype distribution varies with different vaccine adjuvants. Methods: Sera from patients who received a 6MHP vaccine were evaluated with enzyme-linked immunosorbent assays to map epitopes for polyclonal Ab responses to synthetic melanoma peptides. IgG isotypes of Ab responses to 6MHP were assessed in patients who received one of four adjuvants (Incomplete Freund’s Adjuvant (IFA) alone, IFA + polyICLC, IFA + systemic metronomic cyclophosphamide (mCy), or IFA + polyICLC + systemic mCy) to characterize IgG isotype distribution. Results: Epitope mapping revealed that at least 50% of patients had responses to two or more epitopes on the same peptide, suggesting polyclonal Ab responses. Serum evaluation for IgG isotypes showed predominant induction of IgG1 and IgG3. Mean total IgG was highest when IFA and polyICLC were used in combination. Patients who received TLR3 agonist polyICLC had significantly higher concentrations of total IgG, IgG1, and IgG3 compared to patients who did not receive polyICLC. Conclusions: Vaccine-induced Abs may respond to multiple epitopes within the same peptide, warranting further studies into their ability to facilitate antigen uptake and presentation through the formation of large immune complexes. The findings also show that adding polyICLC to IFA can significantly enhance Ab responses. Collectively, this work underscores the immunologic potential of peptide-induced Abs and the importance of adjuvant selection in cancer vaccine design. Full article

Emerging mosquito-borne flaviviruses, such as Dengue virus (DENV) and Zika virus (ZIKV), pose major global public health threats due to their geographic expansion, climate change, and the absence of effective antiviral therapies. Antiviral development against these pathogens has primarily focused on two complementary strategies. On the one hand, the blocking of viral replication by directly inhibiting essential viral enzymes, and on the other, enhancing the host’s innate immune defenses via targeted activation of intracellular antiviral pathways. Among the viral proteins required for replication, the NS2B–NS3 protease complex is one of the most conserved and druggable targets, prompting extensive efforts to design both covalent and non-covalent inhibitors. Covalent inhibitors, such as boronic acids, aldehydes, trifluoromethyl ketones, phenoxymethylphenyl derivatives, and α-ketoamides, form irreversible or slowly reversible bonds with the catalytic serine residue (Ser 135), producing long-lasting and high-affinity suppression of protease activity. In parallel, several classes of non-covalent, particularly allosteric, inhibitors have emerged as promising alternatives with improved specificity and reduced off-target reactivity. A complementary antiviral strategy involves the use of agonists of key innate immune sensors such as TLRs, RIG-I, and the cGAS–STING axis, which mediate the release of interferons (IFNs). This review brings together current knowledge on these two mechanistically distinct yet convergent approaches, highlighting how both can ultimately restrict flavivirus replication. Future opportunities involving modified peptide scaffolds, advanced delivery systems, and drug-repurposing strategies are finally discussed for the development of next-generation therapeutics against DENV and ZIKV. Full article

Background/Objectives: While new vaccines are in development; one strategy to increase influenza vaccine coverage is to repurpose current influenza vaccines for intranasal delivery. Methods: To address this goal; mice were vaccinated intranasally with either a split inactivated virus vaccine (Fluzone) or a recombinant HA vaccine (Flublok) at one of two doses (1 μg high dose or 0.1 μg low dose). Both vaccines were adjuvanted with either a STING agonist; c-di-AMP (CDA); or a combination of a synthetic toll-like receptor (TLR) 4 and TLR7/8 agonist (TRAC478). Results: Mice vaccinated with either vaccine plus adjuvant had higher hemagglutination-inhibition titers than mice administered unadjuvanted vaccines. Mice vaccinated with either vaccine plus CDA had on average higher numbers of H3 and influenza B hemagglutinin (HA)-specific antibody-secreting cells (ASCs); whereas mice vaccinated with vaccine plus TRAC478 had on average higher number of H1 HA-specific ASCs. All vaccinated mice challenged with the H1N1 influenza virus were protected against both morbidity and mortality with no detectable virus in their lungs. Mice challenged with the H3N2 influenza virus all lost weight over the first 5 days of infection. Adding TRAC478 with either a high or low dose vaccine resulted in 80–100% survival following challenge. Almost all mice vaccinated with Flublok plus CDA died from H3N2 influenza virus challenged with ~2 logs higher viral lung titers than mice administered Flublok only or Flublok plus TRAC478. Conclusions: Overall; Fluzone and Flublok can effectively be used for intranasal vaccination. Full article

Background and Objectives: Toll-like receptors (TLRs) are pattern recognition receptors with an essential role in regulating both the innate and adaptive immune response. Given their pleiotropic effects in mounting an immune response, previous studies have proposed targeting these TLRs might render alternative strategies for cancer therapy. Synthetic immune response modifiers, such as imidazoquinolines, stimulate the immune cells by activating Toll-like receptors, particularly TLR7/8 receptors, consequently mounting an immune response. Agonists of this class activate, via TLR-mediated signaling, dendritic and B cells, as well as myeloid cells and T cells, thus exhibiting good prospects for cancer immunotherapy. In the present study, we sought to evaluate the effect of imiquimod and gardiquimod, two TLR 7 and 7/8 agonists, respectively, on tumor growth and phenotype of NK cells associated with melanoma. Materials and Methods: We generated a syngeneic model of melanoma in C57BL/6J mice by subcutaneously injecting murine melanoma cells and monitoring tumor growth. Starting on day 8 or 14, we applied TLR agonists either intratumorally or topically and followed the tumor dynamics and NK cell-associated pattern. Results: Our results suggest that both TLR agonists displayed an antitumor effect along with a phenotypically activated profile of NK cells. Both imiquimod and gardiquimod treatment inhibited tumor growth, with gardiquimod showing an increased potency compared to imiquimod. Conclusions: This implies that TLR agonists like imiquimod and gardiquimod could serve as neoadjuvant, adjuvant, or complementary immunotherapeutic agents in melanoma therapy. Full article

Chronic HBV infection remains a global health challenge, driving liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Liver injury is primarily mediated by host immune responses rather than direct viral cytotoxicity. Macrophages, including Kupffer cells, play dual roles in antiviral defense and disease progression. HBV skews macrophages toward an M2-like, immunosuppressive phenotype, promoting viral persistence and fibrogenesis via cytokines such as Interleukin (IL)-10 and Transforming growth factor-beta (TGF-β). Therapeutic strategies targeting macrophage polarization, including Toll-like receptor (TLR) agonists, immune checkpoint inhibitors, and nanoparticle-based systems, are under investigation. Addressing macrophage heterogeneity and the immunosuppressive hepatic microenvironment using advanced models is essential. Modulating macrophages offers a promising avenue to control HBV, restore immune balance, and mitigate liver injury. This review highlights the central role of macrophages in chronic HBV infection and explores emerging therapeutic strategies. Full article

Background/Objectives: New vaccine platforms that rapidly yield low-cost, easily manufactured vaccines are highly desired, yet current approaches lack key features. We developed the Killed Whole-Cell/Genome-Reduced Bacteria (KWC/GRB) platform, which uses a genome-reduced Gram-negative chassis to enhance antigen exposure and modularity via an autotransporter (AT) system. Integrated within a Design–Build–Test–Learn (DBTL) framework, KWC/GRB enables rapid iteration of engineered antigens and immunomodulatory elements. Here, we applied this platform to the HIV-1 fusion peptide (FP) and tested multiple antigen engineering strategies to enhance its immunogenicity. Methods: For a new vaccine, we synthesized DNA encoding the antigen together with selected immunomodulators and cloned the constructs into a plasmid. The plasmids were transformed into genome-reduced bacteria (GRB), which were grown, induced for antigen expression, and then inactivated to produce the vaccines. We tested multiple strategies to enhance antigen immunogenicity, including multimeric HIV-1 fusion peptide (FP) designs separated by different linkers and constructs incorporating immunomodulators such as TLR agonists, mucosal-immunity-promoting peptides, and a non-cognate T-cell agonist. Vaccines were selected based on structure prediction and confirmed surface expression by flow cytometry. Mice were vaccinated, and anti-FP antibody responses were measured by ELISA. Results: ELISA responses increased nearly one order of magnitude across design rounds, with the top-performing construct showing an ~8-fold improvement over the initial 1mer vaccine. Multimeric antigens separated by an α-helical linker were the most immunogenic. The non-cognate T-cell agonist increased responses context-dependently. Flow cytometry showed that increased anti-FP-mAb binding to GRB was associated with greater induction of antibody responses. Although anti-FP immune responses were greatly increased, the sera did not neutralize HIV. Conclusions: Although none of the constructs elicited detectable neutralizing activity, the combination of uniformly low AlphaFold pLDDT scores and the functional data suggests that the FP region may not adopt a stable native-like structure in this display context. Importantly, the results demonstrate that the KWC/GRB platform can generate highly immunogenic vaccines, and when applied to antigens with well-defined native tertiary structures, the approach should enable rapidly produced, high-response, very low-cost vaccines. Full article

Patients with systemic lupus erythematosus (SLE) often suffer from chronic pain due to a lack of effective and safe analgesics. In this study, we investigated the role of spinal TLR7 in the pathogenesis of chronic pain using female MRL lupus prone (MRL/lpr) mice, a SLE mouse model. We found that from 11 weeks of age, MRL/lpr mice exhibited thermal hypersensitivity in the hind paw, which reached plateau between 14 and 16 weeks. MRL/lpr mice with thermal hypersensitivity had increased expression of TLR7 in the spinal dorsal horn. TLR7 was located in microglia in this region. Intrathecal administration of a TLR7 antagonist attenuated the thermal hypersensitivity in MRL/lpr mice, while administration of the TLR7 agonist induced thermal hypersensitivity in control mice. Pharmacological activation of spinal TLR7 in control mice recapitulated molecular, synaptic, and cellular changes in the spinal dorsal horn of MRL/lpr mice with thermal hyperalgesia. These alterations included activation of microglia and astrocytes, increased production of IL-1β and IL-18, upregulated expression of N-type voltage-gated calcium channels (Cav2.2), enhanced glutamatergic synaptic activity, and elevated neuronal activation. Our findings suggest that targeting TLR7 or downstream effectors may represent a promising strategy to alleviate chronic pain induced by SLE. Full article

Background: Tuberculosis (TB) remains a pressing global health crisis. The inadequate efficacy of the BCG vaccine against adult pulmonary TB underscores the urgent need for novel, effective vaccines. This study aimed to design a novel mRNA vaccine candidate against TB using a rational immunoinformatics approach. Methods: From 13 antigens, >12,000 epitopes were filtered to select 60 optimal peptides (36 CTL, 16 HTL, 8 B-cell), assembled into 25 scaffolds with 49 TLR2/4 agonist configurations. EP9158H underwent structural modeling, 100 ns molecular dynamics, docking, immune simulation, RNAfold, and conservation analysis across 76 strains. Results: EP9158H, encoding 15 CTL, 9 HTL, and 8 B-cell epitopes flanked by TLR2 agonist ESAT-6 and TLR4 agonist HBHA, emerged as the optimal candidate. All 32 constituent epitopes showed >81% conservation, with 81.25% exhibiting perfect identity across MTBC lineages. The scaffold demonstrated high solubility (0.531), broad population coverage (73.76% MHC-I, 88.91% MHC-II), optimal TLR2/4 docking scores (−1359.7 and −1348.3), and robust structural stability (ProSA Z-score −6.18; RMSD 22–27 Å). Immune simulation predicted strong Th1-biased T-cell responses and high levels of antibody titers. RNAfold analysis revealed stable mRNA secondary structures (MFE −1127.5 kcal/mol) supporting efficient translation. Conclusions: EP9158H integrates broad epitope coverage, dual TLR agonism, and validated stability. Compared to single-antigen vaccines, it offers superior strain coverage, enhanced innate activation, and mRNA advantages for CTL induction, warranting experimental validation. Full article