InVivoMAb mouse IgG2b isotype control, unknown specificity

Coronary endothelial dysfunction plays a key role in the pathogenesis of acute coronary syndromes. During myocardial infarction (MI), activated platelets release prothrombotic and proinflammatory factors, contributing to vascular injury and dysfunction. To investigate platelet-mediated endothelial dysfunction, endothelial cells (ECs) were treated with platelet-released factors from patients with MI and non-MI controls undergoing coronary angiography. RNA sequencing revealed that MI platelets induced EC mitochondrial dysfunction, confirmed by reduced mitochondrial membrane potential and disrupted mitochondrial networks. Integrating platelet transcriptomic data, we identified the C-C motif chemokine ligand 3 (CCL3) as significantly up-regulated in MI platelets and a key mediator of EC mitochondrial dysfunction. Blocking its receptor, CCR5, attenuated CCL3 effects. In an independent cohort of 261 patients with established cardiovascular disease, higher circulating CCL3 levels were associated with incident major adverse cardiovascular events. Together, these findings establish a mechanistic link between platelet activation and coronary endothelial dysfunction in MI.

Immune checkpoint blockers (ICBs) have demonstrated substantial efficacy across various malignancies, yet the benefits of ICBs are limited to a subset of patients. Therefore, it is essential to identify novel therapeutic targets. By integrating multi-omics data from cohorts of patients with melanoma treated with ICBs, a positive correlation is observed between tumor CD137L expression and the efficacy of PD-1 blockade. Functionally, CD137L induction in cancer cells significantly enhances anti-tumor immunity by promoting CD8+ T cell survival, both in vivo and in vitro. Mechanistically, helicase-like transcription factor (HLTF) is identified as a pivotal transcriptional regulator of CD137L, controlling its expression through phosphorylation of serine at position 398. Therapeutically, the AMPK agonist AICAR (acadesine) as an inducer of CD137L, exhibiting synergistic effects with PD-1 or CTLA-4 blockade. In summary, our findings elucidate a mechanism controlling CD137L expression and highlight a promising combination therapy to enhance the efficacy of ICBs in melanoma. One Sentence Summary: Inducing co-stimulatory immune checkpoint CD137L expression in melanoma cells enhances T cell-mediated anti-tumor immunity.

In metastasis, the dynamics of tumor-immune interactions during micrometastasis remain unclear. Identifying the vulnerabilities of micrometastases before outbreaking into macrometastases can reveal therapeutic opportunities for metastasis. Here, we report a function of T cell immunoglobulin and mucin domain 3 (TIM3) in tumor cells during micrometastasis using breast cancer (BC) metastasis mouse models. TIM3 is highly upregulated in micrometastases, promoting survival, stemness, and immune escape. TIM3+ tumor cells are specifically selected during early seeding of micrometastasis. Mechanistically, TIM3 increases β-catenin/interleukin-1β (IL-1β) signaling, leading to stemness and immune-evasion by inducing immunosuppressive γδ T cells and reducing CD8 T cells during micrometastasis. Clinical data confirm increased TIM3+ tumor cells in BC metastasis and TIM3+ tumor cells as a biomarker of poor outcome in BC patients. (Neo)adjuvant TIM3 blockade reduces the metastatic seeding and incidence in preclinical models. These findings unveil a specific mechanism of micrometastasis immune-evasion and the potential use of TIM3 blockade for subclinical metastasis.

Immunomodulatory agents benefit a small percentage of patients with oral cancer (OC), a subset of head and neck cancer. Cathepsin S (CTSS), a lysosomal protease, has been frequently associated with tumor immunity. This study aimed to investigate the mechanism by which tumor CTSS affects anti-tumor immunity through the regulation of interleukin-7 (IL-7) to overcome this obstacle.

The lack of T cells in tumors is a major hurdle to successful immune checkpoint therapy (ICT). Therefore, therapeutic strategies promoting T cell recruitment into tumors are warranted to improve the treatment efficacy. Here, we report that Fc-optimized anti-cytotoxic T lymphocyte antigen 4 (CTLA-4) antibodies are potent remodelers of tumor vasculature that increase tumor-associated high endothelial venules (TA-HEVs), specialized blood vessels supporting lymphocyte entry into tumors. Mechanistically, this effect is dependent on the Fc domain of anti-CTLA-4 antibodies and CD4+ T cells and involves interferon gamma (IFNγ). Unexpectedly, we find that the human anti-CTLA-4 antibody ipilimumab fails to increase TA-HEVs in a humanized mouse model. However, increasing its Fc effector function rescues the modulation of TA-HEVs, promotes CD4+ and CD8+ T cell infiltration into tumors, and sensitizes recalcitrant tumors to programmed cell death protein 1 (PD-1) blockade. Our findings suggest that Fc-optimized anti-CTLA-4 antibodies could be used to reprogram tumor vasculature in poorly immunogenic cold tumors and improve the efficacy of ICT.

The incidence of infections attributed to antimicrobial-resistant (AMR) pathogens has increased exponentially over the recent decades reaching 1.27 million deaths worldwide in 2019. Without intervention, these infections are predicted to cause up to 10 million deaths a year and incur costs of up to 100 trillion US dollars globally by 2050. The emergence of AMR bacteria such as the ESKAPEE pathogens, and in particular Pseudomonas aeruginosa and species from the genus Burkholderia, underscores an urgent need for new therapeutic strategies. Monoclonal antibody (mAb) therapy offers a promising alternative to treat and prevent bacterial infections. In this study, we used peptides from highly conserved areas of the bacterial flagellin to generate monoclonal antibodies capable of broad binding to flagellated Gram-negative bacteria. We generated a broadly reactive IgG2bĸ mAb (WVDC-2109) that recognizes P. aeruginosa, Burkholderia sp., and other Gram-negative pathogens of interest. Characterization of the therapeutic potential of this antibody was determined using P. aeruginosa as model. In vitro characterization of WVDC-2109 demonstrated complement-mediated bactericidal activity and enhanced opsonophagocytosis of P. aeruginosa. Prophylactic administration of WVDC-2109 markedly improved survival and outcome in a lethal sepsis model and a sub-lethal murine pneumonia model of P. aeruginosa infection, reducing bacterial burden and inflammation. These findings suggest that WVDC-2109 and similar FliC-targeting antibodies could be valuable in preventing or treating diseases caused by P. aeruginosa as well as other life-threatening diseases of concern.IMPORTANCEAntimicrobial resistance (AMR) costs hundreds of thousands of lives and billions of dollars annually. To protect the population against these infections, it is imperative to develop new medical countermeasures targeting AMR pathogens like P. aeruginosa and Burkholderia sp. The administration of broadly reactive monoclonal antibodies can represent an alternative to treat and prevent infections caused by multi-drug-resistant bacteria. Unlike vaccines, antibodies can provide protection regardless of the immune status of the infected host. In this study, we generated an antibody capable of recognizing flagellin from P. aeruginosa and B. pseudomallei along with other Gram-negative pathogens of concern. Our findings demonstrate that the administration of the monoclonal antibody WVDC-2109 enhances survival rates and outcomes in different murine models of P. aeruginosa infection. These results carry significant implications in the field given that there are no available vaccines for P. aeruginosa.

Patients with Triple Negative Breast Cancer (TNBC) currently lack targeted therapies, and consequently face higher mortality rates when compared to patients with other breast cancer subtypes. The tumor microenvironment (TME) cytokine Oncostatin M (OSM) reprograms TNBC cells to a more stem-like/mesenchymal state, conferring aggressive cancer cell properties such as enhanced migration and invasion, increased tumor-initiating capacity, and intrinsic resistance to the current standards of care. In contrast to OSM, Interferon-β (IFN-β) promotes a more differentiated, epithelial cell phenotype in addition to its role as an activator of anti-tumor immunity. Importantly, OSM suppresses the production of IFN-β, although the mechanism of IFN-β suppression has not yet been elucidated.

Inhibiting the cytotoxic T-lymphocyte-associated protein-4 (CTLA-4)-mediated immune checkpoint system using an anti-CTLA-4 antibody (Ab) can suppress the growth of various cancers, but the detailed mechanisms are unclear. In this study, we established a monoclonal hepatocellular carcinoma cell line (Hepa1-6 #12) and analyzed the mechanisms associated with anti-CTLA-4 Ab treatment. Depletion of CD4+ T cells, but not CD8+ T cells, prevented anti-CTLA-4 Ab-mediated anti-tumor effects, suggesting dependence on CD4+ T cells. Anti-CTLA-4 Ab treatment resulted in recruitment of interferon-gamma (IFN-g)-producing CD4+ T cells, called T-helper 1 (Th1), into tumors, and neutralization of IFN-g abrogated the anti-tumor effects. Moreover, tumor growth suppression did not require major histocompatibility complex (MHC)-I or MHC-II expression on cancer cells. In vitro studies showed that IFN-g can induce cell cycle arrest and apoptosis in tumor cells. Taken together, these data demonstrate that anti-CTLA-4 Ab can exert its anti-tumor effects through Th1-mediated cell cycle arrest and apoptosis.

Treatments of colitis, inflammation of the intestine, rely on induction of immune suppression associated with systemic adverse events, including recurrent infections. This treatment strategy is specifically problematic in the increasing population of patients with cancer with immune checkpoint inhibitor (ICI)-induced colitis, as immune suppression also interferes with the ICI-treatment response. Thus, there is a need for local-acting treatments that reduce inflammation and enhance intestinal healing. Here, we investigated the effect and safety of bacterial delivery of short-lived immunomodulating chemokines to the inflamed intestine in mice with colitis. Colitis was induced by dextran sulfate sodium (DSS) alone or in combination with ICI (anti-PD1 and anti-CTLA-4), and Limosilactobacillus reuteri R2LC (L. reuteri R2LC) genetically modified to express the chemokine CXCL12-1α (R2LC_CXCL12, emilimogene sigulactibac) was given perorally. In addition, the pharmacology and safety of the formulated drug candidate, ILP100-Oral, were evaluated in rabbits. Peroral CXCL12-producing L. reuteri R2LC significantly improved colitis symptoms already after 2 days in mice with overt DSS and ICI-induced colitis, which in benchmarking experiments was demonstrated to be superior to treatments with anti-TNF-α, anti-α4β7, and corticosteroids. The mechanism of action involved chemokine delivery to Peyer's patches (PPs), confirmed by local CXCR4 signaling, and increased numbers of colonic, regulatory immune cells expressing IL-10 and TGF-β1. No systemic exposure or engraftment could be detected in mice, and product feasibility, pharmacology, and safety were confirmed in rabbits. In conclusion, peroral CXCL12-producing L. reuteri R2LC efficiently ameliorates colitis, enhances mucosal healing, and has a favorable safety profile.NEW & NOTEWORTHY Colitis symptoms are efficiently reduced by peroral administration of probiotic bacteria genetically modified to deliver CXCL12 locally to the inflamed intestine in several mouse models.

Immune checkpoint blockade (ICB) approaches have changed the therapeutic landscape for many tumor types. However, half of cutaneous squamous cell carcinoma (cSCC) patients remain unresponsive or develop resistance. Here, we show that, during cSCC progression in male mice, cancer cells acquire epithelial/mesenchymal plasticity and change their immune checkpoint (IC) ligand profile according to their features, dictating the IC pathways involved in immune evasion. Epithelial cancer cells, through the PD-1/PD-L1 pathway, and mesenchymal cancer cells, through the CTLA-4/CD80 and TIGIT/CD155 pathways, differentially block antitumor immune responses and determine the response to ICB therapies. Accordingly, the anti-PD-L1/TIGIT combination is the most effective strategy for blocking the growth of cSCCs that contain both epithelial and mesenchymal cancer cells. The expression of E-cadherin/Vimentin/CD80/CD155 proteins in cSCC, HNSCC and melanoma patient samples predicts response to anti-PD-1/PD-L1 therapy. Collectively, our findings indicate that the selection of ICB therapies should take into account the epithelial/mesenchymal features of cancer cells.

Clinical trials have identified ARID1A mutations as enriched among patients who respond favorably to immune checkpoint blockade (ICB) in several solid tumor types independent of microsatellite instability. We show that ARID1A loss in murine models is sufficient to induce anti-tumor immune phenotypes observed in ARID1A mutant human cancers, including increased CD8+ T cell infiltration and cytolytic activity. ARID1A-deficient cancers upregulated an interferon (IFN) gene expression signature, the ARID1A-IFN signature, associated with increased R-loops and cytosolic single-stranded DNA (ssDNA). Overexpression of the R-loop resolving enzyme, RNASEH2B, or cytosolic DNase, TREX1, in ARID1A-deficient cells prevented cytosolic ssDNA accumulation and ARID1A-IFN gene upregulation. Further, the ARID1A-IFN signature and anti-tumor immunity were driven by STING-dependent type I IFN signaling, which was required for improved responsiveness of ARID1A mutant tumors to ICB treatment. These findings define a molecular mechanism underlying anti-tumor immunity in ARID1A mutant cancers.

Lung cancer is the leading cause of cancer-related deaths in the world, and non-small cell lung cancer (NSCLC) is the most common subset. We previously found that infiltration of tumor inflammatory monocytes (TIMs) into lung squamous carcinoma (LUSC) tumors is associated with increased metastases and poor survival. To further understand how TIMs promote metastases, we compared RNA-Seq profiles of TIMs from several LUSC metastatic models with inflammatory monocytes (IMs) of non-tumor-bearing controls. We identified Spon1 as upregulated in TIMs and found that Spon1 expression in LUSC tumors corresponded with poor survival and enrichment of collagen extracellular matrix signatures. We observed SPON1+ TIMs mediate their effects directly through LRP8 on NSCLC cells, which resulted in TGF-β1 activation and robust production of fibrillar collagens. Using several orthogonal approaches, we demonstrated that SPON1+ TIMs were sufficient to promote NSCLC metastases. Additionally, we found that Spon1 loss in the host, or Lrp8 loss in cancer cells, resulted in a significant decrease of both high-density collagen matrices and metastases. Finally, we confirmed the relevance of the SPON1/LRP8/TGF-β1 axis with collagen production and survival in patients with NSCLC. Taken together, our study describes how SPON1+ TIMs promote collagen remodeling and NSCLC metastases through an LRP8/TGF-β1 signaling axis.

This study systematically analyzed the molecular mechanism and function of nuclear factor kappa B subunit 2 (NFKB2) in colorectal cancer (CRC) to investigate the potential of NFKB2 as a therapeutic target for CRC. Various experimental techniques, including RNA sequencing, proteome chip assays, and small molecule analysis, were used to obtain a deeper understanding of the regulation of NFKB2 in CRC. The results revealed that NFKB2 was upregulated in a significant proportion of patients with advanced hepatic metastasis of CRC. NFKB2 played an important role in promoting tumor growth through CD8+ T-cell exhaustion. Moreover, NFKB2 directly interacted with signal transducer and activator of transcription 2 (STAT2), leading to increased phosphorylation of STAT2 and the upregulation of programmed death ligand 1 (PD-L1). Applying a small molecule inhibitor of NFKB2 (Rg5) led to a reduction in PD-L1 expression and improved response to programmed death-1 blockade-based immunotherapy. In conclusion, the facilitated NFKB2-STAT2/PD-L1 axis may suppress immune surveillance in CRC and targeting NFKB2 may enhance the efficacy of immunotherapeutic strategies. Our results provide novel insights into the molecular mechanisms underlying the contribution of NFKB2 in CRC immune escape.

Chemo-immunotherapy combinations have been regarded as one of the most practical ways to improve immunotherapy response in cancer patients. In this study, we integrate the transcriptomics data from anti-PD-1-treated tumors and compound-treated cancer cell lines to systematically screen for chemo-immunotherapy synergisms in silico. Through analyzing anti-PD-1 induced expression changes in patient tumors, we develop a shift ability score to measure if a chemotherapy or a small molecule inhibitor treatment can shift anti-PD-1 resistance in tumor cells. By applying shift ability analysis to 41,321 compounds and 16,853 shRNA treated cancer cell lines transcriptomic data, we characterize the landscape of chemo-immunotherapy synergism and experimentally validated a mitochondrial RNA-dependent mechanism for drug-induced immune activation in tumor. Our study represents an effort to mechanistically characterize chemo-immunotherapy synergism and will facilitate future pre-clinical and clinical studies.

Coix seed extract (CSE), a traditional Chinese medicine, has been reported as an adjunctive therapy in cancers. However, the molecular targets are largely unclear. The study is designed to unveil its function in lung adenocarcinoma (LUAD) and the possible molecular mechanism.

Protein synthesis is frequently dysregulated in cancer and selective inhibition of mRNA translation represents an attractive cancer therapy. Here, we show that therapeutically targeting the RNA helicase eIF4A with zotatifin, the first-in-class eIF4A inhibitor, exerts pleiotropic effects on both tumor cells and the tumor immune microenvironment in a diverse cohort of syngeneic triple-negative breast cancer (TNBC) mouse models. Zotatifin not only suppresses tumor cell proliferation but also directly repolarizes macrophages toward an M1-like phenotype and inhibits neutrophil infiltration, which sensitizes tumors to immune checkpoint blockade. Mechanistic studies revealed that zotatifin reprograms the tumor translational landscape, inhibits the translation of Sox4 and Fgfr1, and induces an interferon (IFN) response uniformly across models. The induction of an IFN response is partially due to the inhibition of Sox4 translation by zotatifin. A similar induction of IFN-stimulated genes was observed in breast cancer patient biopsies following zotatifin treatment. Surprisingly, zotatifin significantly synergizes with carboplatin to trigger DNA damage and an even heightened IFN response, resulting in T cell-dependent tumor suppression. These studies identified a vulnerability of eIF4A in TNBC, potential pharmacodynamic biomarkers for zotatifin, and provide a rationale for new combination regimens consisting of zotatifin and chemotherapy or immunotherapy as treatments for TNBC.

Cytotoxin-associated gene A (CagA) of Helicobacter pylori (Hp) may promote immune evasion of Hp-infected gastric cancer (GC), but potential mechanisms are still under explored. In this study, the positive rates of CagA and PD-L1 protein in tumor tissues and the high level of exosomal PD-L1 protein in plasma exosomes were significantly associated with the elevated stages of tumor node metastasis (TNM) in Hp-infected GC. Moreover, the positive rate of CagA was positively correlated with the positive rate of PD-L1 in tumor tissues and the level of PD-L1 protein in plasma exosomes, and high level of exosomal PD-L1 might indicate poor prognosis of Hp-infected GC. Mechanically, CagA increased PD-L1 level in exosomes derived from GC cells by inhibiting p53 and miRNA-34a, suppressing proliferation and anticancer effect of CD8+ T cells. This study provides sights for understanding immune evasion mediated by PD-L1. Targeting CagA and exosomal PD-L1 may improve immunotherapy efficacy of Hp-infected GC.

Zoonotic arenavirus infections can result in viral hemorrhagic disease, characterized by platelet loss, petechia, and multi-organ injury. The mechanisms governing these outcomes are likely impacted by virus strain and infection dose, as well as an individual's genetic background and immune constitution. To better understand the processes leading to severe pathogenesis, we compared two strains of inbred mice, C57BL/6J (B6) and FVB/NJ (FVB), that have diametrically opposed outcomes during disseminated lymphocytic choriomeningitis virus (LCMV) infection. Infection caused minimal pathogenesis in B6 mice, whereas FVB mice developed acute hepatitis and perished due, in part, to aberrant NK cell and T cell responses. Susceptible mice showed an outgrowth of cytolytic CD4+ T cells and loss of Treg cells. B6 congenic mice with the FVB allele at a 25Mb locus on chromosome 17 recapitulated FVB pathogenesis upon infection. A locus containing a limited number of variants in immune-related genes greatly impacts survival during infection.