Toll-like Receptor Agonists Research Articles

Safety and efficacy of toll-like receptor agonists as therapeutic agents and vaccine adjuvants for infectious diseases in animals: a systematic review.

Strengthening global health security relies on adequate protection against infectious diseases through vaccination and treatment. Toll-like receptor (TLR) agonists exhibit properties that can enhance immune responses, making them potential therapeutic agents or vaccine adjuvants. We conducted an extensive systematic review to assess the efficacy of TLR agonists as therapeutic agents or vaccine adjuvants for infectious diseases and their safety profile in animals, excluding rodents and cold-blooded animals. We collected qualitative and available quantitative data on the efficacy and safety outcomes of TLR agonists and employed descriptive analysis to summarize the outcomes. Among 653 screened studies, 51 met the inclusion criteria. In this review, 82% (42/51) of the studies used TLR agonists as adjuvants, while 18% (9/51) applied TLR agonist as therapeutic agents. The predominant TLR agonists utilized in animals against infectious diseases was CpG ODN, acting as a TLR9 agonist in mammals, and TLR21 agonists in chickens. In 90% (46/51) of the studies, TLR agonists were found effective in stimulating specific and robust humoral and cellular immune responses, thereby enhancing the efficacy of vaccines or therapeutics against infectious diseases in animals. Safety outcomes were assessed in 8% (4/51) of the studies, with one reporting adverse effects. Although TLR agonists are efficacious in enhancing immune responses and the protective efficacy of vaccines or therapeutic agents against infectious diseases in animals, a thorough evaluation of their safety is imperative to in-form future clinical applications in animal studies. https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=323122.

A Pooled Analysis of Eight Clinical Studies Suggests a Link Between Influenza-Like Symptoms and Pharmacodynamics of the Toll-Like Receptor-7 Agonist Vesatolimod.

Vesatolimod is a Toll-like receptor-7 (TLR7) agonist in clinical development as part of a combination regimen for human immunodeficiency virus (HIV) cure. Influenza-like symptoms associated with TLR7-mediated immune activation have been reported in clinical trials of vesatolimod. Therefore, a broader understanding of the safety profile of vesatolimod and association with dose and mechanism of action will help inform future clinical studies. In this analysis, data on flu-like adverse events of interest (AEIs) were pooled from eight clinical studies in which 606 participants either received single or multiple doses of vesatolimod (0.3-12mg; n = 505) or placebo (n = 101). Vesatolimod pharmacokinetics, inflammatory responses, and pharmacodynamics were assessed. The incidence of flu-like AEIs was higher with vesatolimod versus placebo (19% [96/505] vs. 8% [8/101]) and increased with vesatolimod dose and exposure. Most flu-like AEIs with vesatolimod were grade 1 or 2 severity (55% [53 of 96] grade 1; 35% [34 of 96] grade 2) with onset primarily after the first and second dose. Occurrence of flu-like AEIs after doses 1-3 was predictive of reoccurrence after later doses. Dose-dependent elevations of pharmacodynamic biomarkers (interferon-stimulated gene 15, 2'-5'-oligoadenylate synthetase 1, myxovirus resistance-1, interferon-α, interleukin-1 receptor antagonist, interferon-γ-induced protein 10, interferon-inducible T-cell-α chemoattractant) observed in participants with flu-like AEIs suggest a link with vesatolimod mechanism of action. Flu-like AEIs associated with vesatolimod administration were typically mild but increased with exposure, which may be predicted by the response to initial doses. The data suggest that adaptive clinical monitoring could help maximize pharmacodynamic responses and balance adverse events in future clinical trials of vesatolimod.

Mu-Opioid Receptor (MOR) Dependence of Pain in Chemotherapy-Induced Peripheral Neuropathy.

We recently demonstrated that transient attenuation of Toll-like receptor 4 (TLR4) in dorsal root ganglion (DRG) neurons, can both prevent and reverse pain associated with chemotherapy-induced peripheral neuropathy (CIPN), a severe side effect of cancer chemotherapy, for which treatment options are limited. Given the reduced efficacy of opioid analgesics to treat neuropathic, compared to inflammatory, pain, the crosstalk between nociceptor TLR4 and mu-opioid receptors (MOR), and that MOR and TLR4 agonists induce hyperalgesic priming (priming), which also occurs in CIPN, we determined, using male rats, whether: i ) antisense knockdown of nociceptor MOR attenuates CIPN, ii ) and attenuates the priming associated with CIPN, and iii ) CIPN also produces opioid-induced hyperalgesia (OIH). We found that intrathecal MOR antisense prevents and reverses hyperalgesia induced by oxaliplatin and paclitaxel, two common clinical chemotherapy agents. Oxaliplatin induced-priming was also markedly attenuated by MOR antisense. Additionally, intradermal morphine, at a dose that does not affect nociceptive threshold in controls, exacerbates mechanical hyperalgesia (OIH) in rats with CIPN, suggesting the presence of OIH. This OIH associated with CIPN is inhibited by interventions that reverse Type II priming (the combination of an inhibitor of Src and mitogen-activated protein kinase (MAPK)), a MOR antagonist, as well as a TLR4 antagonist. Our findings support a role of nociceptor MOR in oxaliplatin-induced pain and priming. We propose that priming and OIH are central to the symptom burden in CIPN, contributing to its chronicity and the limited efficacy of opioid analgesics to treat neuropathic pain.Significance Statement It remains unknown why opioid analgesics are less effective against neuropathic pain, including that induced by cancer chemotherapy. Here we demonstrate a crucial role of nociceptor mu-opioid receptors (MOR) in chemotherapy-induced peripheral neuropathy (CIPN) pain and hyperalgesic priming (priming), the latter a mechanism involved in the transition from acute to chronic pain. In addition to neuropathic pain and priming, opioid-induced hyperalgesia (OIH) also develops in chemotherapy-treated rats, which is reversed by inhibitors of second messengers that also reverse Type II priming, as well as by MOR and TLR4 antagonists. Taken together our results support the suggestion that priming and OIH contribute to CIPN and its limited responsiveness to opioid analgesics.

A Photoactivatable Self-Assembled Nanoagonist for Synergistic Therapy against Pancreatic Ductal Adenocarcinoma.

Immunotherapy has revolutionized the cancer treatment paradigm, yet efficient immunotherapeutic responses against immune-cold/desert cancers remain challenging. Herein, we report that photoactivatable nanoagonists yield a potent antitumor synergy of photoimmunotherapy against pancreatic ductal adenocarcinoma (PDAC). The nanoagonist was fabricated by assembling an amphiphilic boron dipyrromethene-derived polymer conjugated with a Toll-like receptor agonist via a photocleavable linker and stimulator of interferon genes agonist. The nanoagonist enables light-induced generation of reactive oxygen species and on-demand release of the agonists to yield synergistic photoimmunotherapy. The produced tumor antigens promote dendritic cell maturation, which is further amplified by these agonists for eliciting adaptive immunity, accompanied by apparently abscopal and long-term memory effects. The nanoagonist further alleviates the fibrosis of tumor stroma and the immunosuppressive microenvironment, leading to the deep infiltrations of clinically used therapeutics and immune cells to yield preferable combinational treatments against PDAC models. These results provide valuable insights into activatable nanoparticles for cancer therapy against immune-desert cancers.

The Protective Effects of Mcl-1 on Mitochondrial Damage and Oxidative Stress in Imiquimod-Induced Cancer Cell Death.

Mitochondria, vital organelles that generate ATP, determine cell fate. Dysfunctional and damaged mitochondria are fragmented and removed through mitophagy, a mitochondrial quality control mechanism. The FDA-approved drug IMQ, a synthetic agonist of Toll-like receptor 7, exhibits antitumor activity against various skin malignancies. We previously reported that IMQ promptly reduced the level of the antiapoptotic Mcl-1 protein and that Mcl-1 overexpression attenuated IMQ-triggered apoptosis in skin cancer cells. Furthermore, IMQ profoundly disrupted mitochondrial function, promoted mitochondrial fragmentation, induced mitophagy, and caused cell death by generating high levels of ROS. However, whether Mcl-1 protects mitochondria from IMQ treatment is still unknown. In this study, we demonstrated that Mcl-1 overexpression induced resistance to IMQ-induced apoptosis and reduced both IMQ-induced ROS generation and oxidative stress in cancer cells. Mcl-1 overexpression maintained mitochondrial function and integrity and prevented mitophagy in IMQ-treated cancer cells. Furthermore, IL-6 protected against IMQ-induced apoptosis by increasing Mcl-1 expression and attenuating IMQ-induced mitochondrial fragmentation. Mcl-1 overexpression ameliorates IMQ-induced ROS generation and mitochondrial fragmentation, thereby increasing mitochondrial stability and ultimately attenuating IMQ-induced cell death. Investigating the roles of Mcl-1 in mitochondria is a potential strategy for cancer therapy development.

Abstract 15: Cell-Free Mitochondrial DNA Drives Endothelial Cell Activation and Vascular Dysfunction via Toll-Like Receptor 9 and Inflammasome Pathway Activation

Immune system activation has been shown to play an important role in the pathogenesis of hypertension and substantial evidence has been highlighting the importance of inflammasomes in vascular disease progression. Mitochondria damage leads to mitochondrial DNA (mtDNA) releasing into the cytoplasm, which, in turn, triggers the activation of leucine-rich-containing (NLR) family pyrin domain containing 3 (NLRP3) and absent in melanoma 2 (AIM2) inflammasomes, thereby exacerbating inflammation. However, whether mtDNA release-dependent exacerbation of inflammasomes drives endothelial cell activation and vascular damage remains to be elucidated. We hypothesize that cytosolic mtDNA release triggers endothelial cell activation and inflammation via Toll-Like Receptor 9 (TLR9) and inflammasome pathway activation, leading to vascular dysfunction. To assess this hypothesis, a concentration-response curve to endothelin-1 (ET-1) was performed in mesenteric resistance arteries (MRAs) isolated from wild-type and TLR9 knockout C57 mice in the presence or absence of mtDNA (4ug/mL) for one hour. To test inflammasome pathway activation, vascular smooth muscle cells (VSMC) and endothelial cells (EC) were incubated with TLR9 agonist (ODN2395, 3uM) or mtDNA (4ug/mL) and co-incubated with TLR9/AIM2 inhibitor (ODN2088, 2uM) or NLRP3 inhibitor (MCC950, 10uM) for 24 hours. Protein expression was assessed via Western blot and immunophenotyping was performed by flow cytometry. Data are presented as mean ± S.E.M and significance was set at p<0.05. After incubation with mtDNA, MRAs from wild-type mice presented an increased contractile response to ET-1 which was prevented in TLR9 KO mice. In VSMC, TLR9 expression increased after incubation with ODN2395 (vehicle: 1.2 ± 0.2 vs ODN2395: 4 ± 1.5) or mtDNA (vehicle: 1.2 ± 0.2 vs mtDNA: 4.2 ± 1.2) while co-incubation with ODN2088 reversed this effect. Additionally, mtDNA promoted increased TNF-alpha (vehicle: 1 ± 0.1 vs mtDNA: 2.6 ± 0.5) and IL-6 (vehicle: 1 ± 0.1 vs mtDNA: 4.6 ± 0.3) expression in VSMC which was abolished in the presence of ODN2088. In EC, flow cytometry indicated that incubation with mtDNA promoted a 4-fold increase in the expression of CD31+ and a 2-fold increase in CD54+ cells while co-incubation with ODN2088 or MCC950 reversed this effect. Altogether these data suggest that cell-free mtDNA triggers the innate immune response via TLR9 and inflammasomes driving EC activation, vascular dysfunction, and inflammation.

TLR agonists promote formation of Tertiary Lymphoid Structure and improve anti-glioma immunity.

Glioma, characterized by limited lymphocytic infiltration, constitutes an "immune-desert" tumor displaying insensitivity to various immunotherapies. This study aims to explore therapeutic strategies for inducing tertiary lymphoid structure (TLS) formation within the glioma microenvironment (GME) to transition it from an immune-resistant to an activated state. TLS formation in GME was successfully induced by intracranial administration of Toll-like receptor (TLR) agonists (OK-432, TLR2/4/9 agonist) and glioma antigens (i.c. αTLR-mix). We employed staining analysis, antibody neutralization, single-cell RNA sequencing (scRNA-Seq), and BCR/TCR sequencing to investigate the underlying mechanisms of TLS formation and its role in anti-glioma immunity. Additionally, a preliminary translational clinical study was conducted. TLS formation correlated with increased lymphocyte infiltration in GME and led to improved prognosis in glioma-bearing mice. In the study of TLS induction mechanisms, certain macrophages/microglia and Th17 displayed markers of "LTo" and "LTi" cells, respectively, interaction through LTα/β-LTβR promoted TLS induction. Post-TLS formation, CD4+ and CD8+ T cells but not CD19+ B cells contributed to anti-glioma immunity. Comparative analysis of B/T cells between brain and lymph node showed that brain B/T cells unveiled switch from naïve to mature, some B cells highlighted an enrichment of CSR-associated genes, V gene usage and clonotype bias were observed. In related clinical studies, i.c. αTLR-mix treatment exhibited tolerability, and chemokines/cytokines assay provided preliminary evidence supporting TLS formation in GME. TLS induction in GME enhanced anti-glioma immunity, improved the immune microenvironment, and controlled glioma growth, suggesting potential therapeutic avenues for treating glioma in the future.

Synergistic immune augmentation enabled by covalently conjugating TLR4 and NOD2 agonists

Enhancing the efficacy of subunit vaccines relies significantly on the utilization of potent adjuvants, particularly those capable of triggering multiple immune pathways. To achieve synergistic immune augmentation by Toll-like receptor 4 agonist (TLR4a) and nucleotide-binding oligomerization-domain-containing protein 2 agonist (NOD2a), in this work, we conjugated RC529 (TLR4a) and MDP (NOD2a) to give RC529-MDP, and evaluated its adjuvanticity for OVA antigen. Compared to the unconjugated RC529+MDP, RC529-MDP remarkably enhanced innate immune responses with 6.8-fold increase in IL-6 cytokine, and promoted the maturation of antigen-presenting cells (APCs), possibly because of the conjugation of multiple agonists ensuring their delivery to the same cell and activation of various signaling pathways within that cell. Furthermore, RC529-MDP improved OVA-specific antibody response, T cells response and the memory T cells ratio relative to the unconjugated mixture. Therefore, covalently conjugating TLR4 agonist and NOD2 agonist was an effective strategy to enhance immune responses, providing the potential to design and develop more effective vaccines.

Maternal immune activation by toll-like receptor 7 agonist during mid-gestation increases susceptibility to blood-brain barrier leakage after puberty

Maternal immune activation (MIA), a maternal stressor, increases risk for neuropsychiatric diseases, such as Major Depressive Disorder in offspring. MIA of toll-like receptor 7 (TLR7) initiates an immune response in mother and fetuses in a sex-selective manner. The paraventricular nucleus of the hypothalamus (PVN), a brain region that is sexually dimorphic and regulates hypothalamic-pituitary-adrenal (HPA) stress responses, have been tied to stress-related behaviors (i.e., depression, anxiety, social impairments). The current study characterized the sex-selective impact of mid-gestational TLR7 activation on PVN vasculature of adult offspring based on a prior study of excess prenatal glucocorticoid stress. The PVN of offspring were evaluated to determine if fetal MIA impacted vascular leakage in the brains of adult mice with or without restraint stress. Timed-pregnant female mice were administered the TLR7 agonist Resiquimod (RQ) or saline vehicle on embryonic day (E) 12.5. Basal and restraint stress-induced corticosterone was measured to examine changes in stress response. Mice were perfused transcardially with fluorescein isothiocyanate (FITC) to assess blood vessel integrity. Sections with FITC-labeled blood vessels through the PVN of offspring were immunolabeled for Glial Fibrillary Acidic Protein (GFAP; astrocytic end feet) and IBA-1 (microglia). MIA with RQ led to elevated levels of plasma corticosterone 60-minutes after restraint in offspring, suggesting prenatal RQ impairs glucocorticoid negative feedback. Blood-brain barrier integrity was assessed. Adult offspring of RQ injected dams showed greater leakage in the PVN (greater in males than females). GFAP+ colocalization with FITC-labeled vessels was lower in the PVN of offspring from RQ treated dams, potentially contributing to the observed increased FITC leakage. Microglia were examined in relation to the vasculature as an indicator of a neuroimmune response. Data show IBA-1+ cells greater in size and number in the PVN with closer proximity to blood vessels after maternal injection of RQ in a male-selective manner. Microglia were unchanged in females from RQ-treated dams but were smaller in size after restraint. This study provides support for sex-selective influences of fetal immune antecedents for altered brain vascular and blood brain barrier development and adult neuroendocrine function that could indicate a PVN locus for increased susceptibility for adult disorders.

The Expression of Toll-like Receptors in Cartilage Endplate Cells: A Role of Toll-like Receptor 2 in Pro-Inflammatory and Pro-Catabolic Gene Expression.

The vertebral cartilage endplate (CEP), crucial for intervertebral disc health, is prone to degeneration linked to chronic low back pain, disc degeneration, and Modic changes (MC). While it is known that disc cells express toll-like receptors (TLRs) that recognize pathogen- and damage-associated molecular patterns (PAMPs and DAMPs), it is unclear if CEP cells (CEPCs) share this trait. The CEP has a higher cell density than the disc, making CEPCs an important contributor. This study aimed to identify TLRs on CEPCs and their role in pro-inflammatory and catabolic gene expression. Gene expression of TLR1-10 was measured in human CEPs and expanded CEPCs using quantitative polymerase chain reaction. Additionally, surface TLR expression was measured in CEPs grouped into non-MC and MC. CEPCs were stimulated with tumor necrosis factor alpha, interleukin 1 beta, small-molecule TLR agonists, or the 30 kDa N-terminal fibronectin fragment. TLR2 signaling was inhibited with TL2-C29, and TLR2 protein expression was measured with flow cytometry. Ex vivo analysis found all 10 TLRs expressed, while cultured CEPCs lost TLR8 and TLR9 expression. TLR2 expression was significantly increased in MC1 CEPCs, and its expression increased significantly after pro-inflammatory stimulation. Stimulation of the TLR2/6 heterodimer upregulated TLR2 protein expression. The TLR2/1 and TLR2/6 ligands upregulated pro-inflammatory genes and matrix metalloproteases (MMP1, MMP3, and MMP13), and TLR2 inhibition inhibited their upregulation. Endplate resorptive capacity of TLR2 activation was confirmed in a CEP explant model. The expression of TLR1-10 in CEPCs suggests that the CEP is susceptible to PAMP and DAMP stimulation. Enhanced TLR2 expression in MC1, and generally in CEPCs under inflammatory conditions, has pro-inflammatory and pro-catabolic effects, suggesting a potential role in disc degeneration and MC.

Endosomal Toll-Like Receptors intermediate negative impacts of viral diseases, autoimmune diseases, and inflammatory immune responses on the cardiovascular system.

Cardiovascular disease (CVD) is the leading cause of morbidity globally, with chronic inflammation as a key modifiable risk factor. Toll-like receptors (TLRs), pivotal components of the innate immune system, including TLR-3, -7, -8, and -9 within endosomes, trigger intracellular cascades, leading to inflammatory cytokine production by various cell types, contributing to systemic inflammation and atherosclerosis. Recent research highlights the role of endosomal TLRs in recognizing self-derived nucleic acids during sterile inflammation, implicated in autoimmune conditions like myocarditis. This review explores the impact of endosomal TLRs on viral infections, autoimmunity, and inflammatory responses, shedding light on their intricate involvement in cardiovascular health and disease by examining literature on TLR-mediated mechanisms and their roles in CVD pathophysiology. Removal of endosomal TLRs mitigates myocardial damage and immune reactions, applicable in myocardial injury. Targeting TLRs with agonists enhances innate immunity against fatal viruses, lowering viral loads and mortality. Prophylactic TLR agonist administration upregulates TLRs, protecting against fatal viruses and improving survival. TLRs play a complex role in CVDs like atherosclerosis and myocarditis, with therapeutic potential in modulating TLR reactions for cardiovascular health.

Vascular injury derived apoptotic exosome-like vesicles trigger autoimmunity

According to a central tenet of classical immune theory, a healthy immune system must avoid self-reactive lymphocyte clones but we now know that B cells repertoire exhibit some level of autoreactivity. These autoreactive B cells are thought to rely on self-ligands for their clonal selection and survival. Here, we confirm that healthy mice exhibit self-reactive B cell clones that can be stimulated in vitro by agonists of toll-like receptor (TLR) 1/2, TLR4, TLR7 and TLR9 to secrete anti-LG3/perlecan. LG3/perlecan is an antigen packaged in exosome-like structures released by apoptotic endothelial cells (ApoExos) upon vascular injury. We demonstrate that the injection of ApoExos in healthy animals activates the IL-23/IL-17 pro-inflammatory and autoimmune axis, and produces several autoantibodies, including anti-LG3 autoantibodies and hallmark autoantibodies found in systemic lupus erythematosus. We also identify γδT cells as key mediators of the maturation of ApoExos-induced autoantibodies in healthy mice. Altogether we show that ApoExos released by apoptotic endothelial cells display immune-mediating functions that can stimulate the B cells in the normal repertoire to produce autoantibodies. Our work also identifies TLR activation and γδT cells as important modulators of the humoral autoimmune response induced by ApoExos.

Saponin nanoparticle adjuvants incorporating Toll-like receptor agonists drive distinct immune signatures and potent vaccine responses.

Over the past few decades, the development of potent and safe immune-activating adjuvant technologies has become the heart of intensive research in the constant fight against highly mutative and immune evasive viruses such as influenza, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and human immunodeficiency virus (HIV). Herein, we developed a highly modular saponin-based nanoparticle platform incorporating Toll-like receptor agonists (TLRas) including TLR1/2a, TLR4a, and TLR7/8a adjuvants and their mixtures. These various TLRa-saponin nanoparticle adjuvant constructs induce unique acute cytokine and immune-signaling profiles, leading to specific T helper responses that could be of interest depending on the target disease for prevention. In a murine vaccine study, the adjuvants greatly improved the potency, durability, breadth, and neutralization of both COVID-19 and HIV vaccine candidates, suggesting the potential broad application of these adjuvant constructs to a range of different antigens. Overall, this work demonstrates a modular TLRa-SNP adjuvant platform that could improve the design of vaccines and affect modern vaccine development.

Multi-Drug Resistance and Breast Cancer Progression via Toll-Like Receptors (TLRs) Signaling.

Toll-like receptors (TLRs) are essential receptors involved in inflammation and innate immunity. Various types of cancer cells, as well as innate immune cells, express TLRs. There is mounting proof that TLRs are critical to the development and spread of cancer as well as metabolism. In breast cancer, up-regulated levels of TLRs have been linked to the aggressiveness of the diseases, worse treatment outcomes, and the emergence of therapeutic resistance. Patients with advanced non-resectable, recurring, and metastatic breast cancer currently have few available treatment choices. An intriguing new strategy is an innate immunity-mediated anticancer immunotherapy, either used alone or in conjunction with existing treatments. In fact, several TLR agonists and antagonists have been used in clinical studies for anti-cancer immunotherapy. Consequently, TLRs serve as critical targets for controlling the course of breast cancer and treatment resistance in addition to being implicated in immune responses against pathogen infection and cancer immunology. In this review, we deliver an overview of the most current findings on TLR involvement in the development of breast cancer and treatment resistance.

Extracellular RNA Induces Neutrophil Recruitment Via Toll-Like Receptor 3 During Venous Thrombosis After Vascular Injury.

Venous thromboembolism is associated with endothelial cell activation that contributes to the inflammation-dependent activation of the coagulation system. Cellular damage is associated with the release of different species of extracellular RNA (eRNA) involved in inflammation and coagulation. TLR3 (toll-like receptor 3), which recognizes (viral) single-stranded or double-stranded RNAs and self-RNA fragments, might be the receptor of these species of eRNA during venous thromboembolism. Here, we investigate how the TLR3/eRNA axis contributes to venous thromboembolism. Thrombus formation and size in wild-type and TLR3 deficient (-/-) mice were monitored by ultrasonography after venous thrombosis induction using the ferric chloride and stasis models. Mice were treated with RNase I, with polyinosinic-polycytidylic acid, a TLR3 agonist, or with RNA extracted from murine endothelial cells. Gene expression and signaling pathway activation were analyzed in HEK293T cells overexpressing TLR3 in response to eRNA or in human umbilical vein endothelial cells transfected with a small interference RNA against TLR3. Plasma clot formation on treated human umbilical vein endothelial cells was analyzed. Thrombosis exacerbated eRNA release invivo and increased eRNA content within the thrombus. RNase I treatment reduced thrombus size compared with vehicle-treated mice (P<0.05). Polyinosinic-polycytidylic acid and eRNA treatments increased thrombus size in wild-type mice (P<0.01 and P<0.05), but not in TLR3-/- mice, by reinforcing neutrophil recruitment (P<0.05). Mechanistically, TLR3 activation in endothelial cells promotes CXCL5 (C-X-C motif chemokine 5) secretion (P<0.001) and NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) activation (P<0.05). Finally, eRNA triggered plasma clot formation invitro (P<0.01). We show that eRNA and TLR3 activation enhance venous thromboembolism through neutrophil recruitment possibly through secretion of CXCL5, a potent neutrophil chemoattractant.

Vaccination with ancestral SARS-CoV-2 spike adjuvanted with TLR agonists provides cross-protection against XBB.1

Many different platforms have been used to develop highly protective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in humans. However, protection has eroded over time due to the emergence of antigenically diverse viral variants, especially the Omicron subvariants. One successful platform for the generation of SARS-CoV-2 vaccines are recombinant spike protein vaccines, of which two are licensed in the United States and Europe. Typically, purified recombinant protein antigens are poorly immunogenic and adjuvants must be included in the formulation. Here, we adjuvanted recombinant ancestral SARS-CoV-2 Wuhan-Hu-1 spike proteins with an emulsion formulation combined with synthetic Toll-like receptor (TLR) 4 and 7/8 agonists. This combination led to the induction of a Th1-skewed immune response that included high titers of antibodies against Wuhan-Hu-1 spike. These serum antibodies included neutralizing and cross-reactive antibodies that recognized the spike from multiple SARS-CoV-2 variants, as well as the receptor binding domain (RBD) from SARS-CoV-1. Despite an absence of robust cross-neutralization, vaccination against Wuhan-Hu-1 spike in the context of TLR-containing emulsions provided complete cross-protection against disease from a lethal challenge with XBB.1 in a stringent K18-hACE2 mouse model. We believe that the combination of recombinant spike antigens with TLR agonist-based emulsion formulations could lead to the development of next-generation SARS-CoV-2 vaccines that provide significant protection from future emerging variants.

Effects of Yeast-Enriched Functionalized Canola Meal Supplementation on Apparent Total Tract Macronutrient Digestibility and Fecal Characteristics, Fecal Microbiota, and Immune Function of Healthy Adult Dogs.

Brewer's dried yeast has a high nutritional value and has long been utilized by the animal feed industry as a source of protein, B-complex vitamins, and minerals. Brewer's dried yeast is also rich in bioactive compounds and may thereby be used as a functional ingredient, providing benefits beyond that of its nutrient content. Canola meal is a high-fiber ingredient that also has unique properties, especially when it is wetted and dried using a proprietary drying system that creates a "functionalized" canola meal. The objective of this experiment was to evaluate the effects of a yeast-enriched functionalized canola meal (FCM) on apparent total tract digestibility (ATTD) and the fecal quality, metabolite concentrations, and microbiota populations, and immune function of healthy adult dogs. Twelve adult female beagles [body weight (BW) = 7.6 ± 0.7kg; age = 5.8 ± 1.3] were used in a replicated 4×4 Latin square design with 28-d periods. Each experimental period consisted of a 22-d adaptation phase, 5 days of total and fresh fecal collection, and blood collection on the last day. To start, all dogs were fed a basal diet to maintain BW for 14 d. Following fecal and blood collections at baseline (-1 d) to confirm health status, experimental periods began testing the following dietary treatments using a Latin square design experiment: 1) FCM only (no yeast inclusion), 2) FCM + low yeast dose, 3) FCM + medium yeast dose, and 4) FCM + high yeast dose. All treatments were top-dressed onto the basal diet at a rate estimated to be 1% of daily intake (as-is basis). Statistical analysis was performed using the PROC MIXED procedure of SAS with the main effect of treatment and the random effect of dog. Significance was declared at P ≤ 0.05, and trends reported if 0.05 < P ≤ 0.10. Supplementation with yeast-enriched FCM had no significant effect on the ATTD of macronutrients or energy or the fecal characteristics, metabolite concentrations, and microbiota populations of dogs. Additionally, no significant differences were observed in circulating immune cell counts or response to Toll-like receptor agonists among treatments. Our results suggest that the yeast-enriched FCM could be included in canine diets without negatively affecting stool quality, fecal metabolite concentrations, or ATTD. Further research is necessary to determine the effective dose of yeast-enriched FCM, potential mechanisms of action, and other potential implications it has on canine health.

Tumor microenvironment-responsive macrophage-mediated immunotherapeutic drug delivery

Immunotherapy, as a promising treatment strategy for cancer, has been widely employed in clinics, while its efficiency is limited by the immunosuppression of tumor microenvironment (TME). Tumor-associate macrophages (TAMs) are the most abundant immune cells infiltrating the TME and play a crucial role in immune regulation. Herein, a M0-type macrophage-mediated drug delivery system (PR-M) was designed for carrying Toll-like receptors (TLRs) agonist-loaded nanoparticles. When TLR agonist R848 was released by responding to the TME, the PR-Ms were polarized from M0-type to M1-type and TAMs were also stimulated from M2-type to M1-type, which eventually reversed the immunosuppressive states of TME. By synergizing with the released R848 agonists, the PR-M significantly activated CD4+ and CD8+ T cells in the TME and turned the ‘cold’ tumor into ‘hot’ tumor by regulating the secretion of cytokines including IFN-γ, TNF-α, IL-10, and IL-12, thus ultimately promoting the activation of antitumor immunity. In a colorectal cancer mouse model, the PR-M treatment effectively accumulated at the tumor site, with a 5.47-fold increase in M1-type and a 65.08 % decrease in M2-type, resulting in an 85.25 % inhibition of tumor growth and a 87.55 % reduction of tumor volume compared with the non-treatment group. Our work suggests that immune cell-mediated drug delivery systems can effectively increase drug accumulation at the tumor site and reduce toxic side effects, resulting in a strong immune system for tumor immunotherapy. Statement of significanceThe formation of TME and the activation of TAMs create an immunosuppressive network that allows tumor to escape the immune system and promotes its growth and spread. In this study, we designed an M0-type macrophage-mediated drug delivery system (PR-M). It leverages the synergistic effect of macrophages and agonists to improve the tumor immunosuppressive micro-environment by increasing M1-type macrophages and decreasing M2-type macrophages. As part of the treatment, the drug-loaded macrophages endowed the system with excellent tumor targeting. Furthermore, loading R848 into TME-responsive nanoparticles could protect macrophages and reduce the potential toxicity of agonists. Further investigations demonstrated that the designed PR-M could be a feasible strategy with high efficacy in tumor targeting, drug loading, autoimmunity activation, and lower side effects.

Using exploratory pharmacokinetic and pharmacodynamic analyses to predict the probability of flu-like symptoms in healthy volunteers and patients with chronic hepatitis B treated with the toll-like receptor 7 agonist ruzotolimod.

Ruzotolimod (Toll-like receptor 7 (TLR7) agonist, RG7854) is an oral, small molecule immuno-modulator activating the TLR 7 and is being evaluated in patients with CHB. As with other TLR7 agonists, the study drug-related adverse events of flu-like symptoms have been reported in some participants during phase I studies with ruzotolimod. An exploratory analysis of the relationship between pharmacokinetic (PK)/pharmacodynamic (PD) and flu-like symptoms was performed in participants from two phase I studies including both healthy volunteers and NUC-suppressed CHB patients who received either single or multiple ascending doses of orally administered ruzotolimod. Linear and logistic regression were used to explore potential relationships between dose, flu-like symptoms, PK, and PD. Generalized linear regression was performed to predict the probability of flu-like symptoms of all intensities at different RO7011785 (the active metabolite of the double prodrug ruzotolimod) PK exposure. This analysis showed that single or multiple doses of ruzotolimod at ⩾100 mg, the immune PD (IFN-α, neopterin, IP-10, and the transcriptional expression of ISG15, OAS-1, MX1, and TLR7) responses increase with the RO7011785 PK exposure, which increases linearly with the doses from 3 mg to 170 mg of ruzotolimod. The analysis also showed that the probability of flu-like symptoms occurrence increases with PD responses (IFN-α and IP-10). Dose reduction of ruzotolimod can be an effective way to reduce the magnitude of PD response, thus reducing the probability of study drug-related flu-like symptoms occurrence at all intensity in the participants who are highly sensitive to PD activation and intolerant to flu-like symptoms.

Expression of the receptor for IgM (FcμR) by bovine neutrophils

Bovine neutrophils possess a particular set of receptors for immunoglobulins. They have been shown to express a distinctive receptor for IgG2, and it has long been known that they interact poorly with IgG1 but that they can use IgM antibodies as opsonins. We show that the binding of labeled IgM was inhibited by unlabeled IgM but not by IgA, suggesting that bovine neutrophils express a specific IgM receptor. The binding of non-aggregated IgM is strong at 4 °C, but shedding occurs at 37 °C. We designed anti-peptide antibodies based on the sequence of the FcμR, the newly described receptor for IgM. These antibodies bound to bovine neutrophils at 4 °C. At 37 °C, labeling was lost, but the loss was inhibited by pretreatment with cytochalasin D, indicating internalization of the receptor after cross-linking by antibodies. Neutrophils that had internalized the receptor were no longer able to bind IgM. Eosinophils showed a low level of FcμR expression. FcμR expression by neutrophils was not increased by stimulation with Toll-like receptor agonists or the complement anaphylatoxin C5a, and decreased by TNF-α. Exposure of neutrophils to IFN-γ for 18 h increased FcμR expression without augmenting the binding of IgG1 or IgG2. We confirmed that bovine neutrophils can use IgM to phagocytose and kill bacteria without the help of Complement. Neutrophils that have migrated into the lumen of inflamed lactating mammary glands expressed the FcμR. These results indicate that bovine neutrophils express an IgM receptor, the FcμR, which is functional to contribute to the opsonophagocytosis of bacteria at inflammatory sites. Expression of the FcμR by neutrophils gives IgM a particular importance for the immune defense in the bovine species.