InVivoMAb rat IgG2a isotype control, anti-trinitrophenol

Alpha-defensin 1 is a small antimicrobial peptide that acts as the first line of defense against pathogens. It is induced following microbial cues and inflammatory signals in neutrophils and Paneth cells in the small intestine, which suggests that it plays a role in microbial homeostasis in the gut. The gut microbial products also serve as ligands for the aryl hydrocarbon receptor (AhR), an environmental sensor. In the current study, we investigated if there is any crosstalk between AhR and alpha-defensin 1. Interestingly, we found a positive correlation between AhR and alpha-defensin 1 protein levels in ileal tissues from active Crohn's' (CD) patients and epithelial cells (IECs) from multiple models of murine colitis. In vitro downregulation of AhR led to inhibition of α-defensin 1, while activation of AhR induced α-defensin 1 in IECs. AhR directly targeted the dioxin response element 3 (DRE3) region on the α-defensin 1 promoter in IECs. AhR-mediated induction of α-defensin 1 in colitis mice reversed the gut microbial dysbiosis and alleviated colitis. Our data identify a novel signaling pathway in which AhR acts as a transcription factor for α-defensin 1, leading to regulation of homeostasis between gut microbiota, intestinal mucosa, and mucosal immunity.

Immune checkpoint blockade (ICB) therapies, such as anti-PD-1, have transformed cancer treatment, but many patients do not respond due to a non-inflammatory tumor microenvironment (TME). Here, we investigated the impact of targeting Atypical Chemokine Receptor 2 (ACKR2), which scavenges key chemokines involved in immune cell recruitment, on the improvement of anti-PD-1-based therapy. In a melanoma mouse model, we demonstrated that Ackr2 inhibition increases the release of proinflammatory chemokines CCL5 and CXCL10 and enhances the infiltration of NK cells, activated CD8+ and CD4+ effector T cells while reducing regulatory T cells (Tregs) in the TME. Targeting Ackr2 led to tumor growth inhibition, improved survival, and enhanced response to anti-PD-1 therapy. In BRAF- and NRAS-mutant melanoma patients, low ACKR2 expression or high CCL5/CXCL10 levels correlated with improved survival and higher CD8+ T cell markers. Targeting ACKR2 represents a promising approach for developing combination therapies, particularly for 'cold' ICB resistant tumors.

Extensive studies have demonstrated the relationship between metabolic reprogramming and the tumor microenvironment. Here, we characterized the head and neck squamous cell carcinoma (HNSCC) evolutionary landscape using spatial metabolomics/transcriptomics, single-cell transcriptomics, and bulk multi-omics. Metabolic heterogeneity during HNSCC malignant transformation was identified, with significant enrichment in the purine metabolism. Integrating single-cell and bulk data, we developed a robust ligand-receptor-based signature (LRS) linked to NT5E, a key upstream regulator of purine metabolism, which served as an independent prognostic indicator. The low LRS subtype was associated with a high proportion of immune cell infiltration and improved response to immunotherapy. Notably, in vitro and in vivo experiments demonstrated that AMIGO2, a core molecule within the LRS, regulates tumor-associated purine metabolism, and that its downregulation suppresses tumor cell invasion and migration, inhibits myofibroblast differentiation, and promotes immune effector cell infiltration. Moreover, combining AMIGO2 targeting with anti-PD-1 therapy yielded superior efficacy. Consistent validation was also obtained in a clinical cohort of HNSCC and premalignancy patients.

Oncolytic virus M1 (OVM), a naturally occurring alphavirus, has demonstrated potent antitumor activity in various solid tumor models by inducing immunogenic cell death and activating CD8+ T cells. However, its in vivo efficacy varies widely, and resistance mechanisms remain poorly understood. Tumor-associated macrophages (TAMs), key immunosuppressive cells within the tumor microenvironment, may limit OVM therapeutic potential.

Despite progress in immunotherapy for several solid tumors, pancreatic ductal adenocarcinoma (PDAC) remains largely unresponsive, primarily due to its profoundly immunosuppressive tumor microenvironment (TME) characterized by limited CD8+ T cell infiltration. Novel strategies are needed to overcome this immune resistance and enhance the efficacy of checkpoint blockade.

A unique strain of Staphylococcus epidermidis, AIT01 (AIT, Airway Immune Trainer), identified in our previous research, has demonstrated immune-boosting properties. This study aimed to evaluate the systemic immune-modulatory effects and potential anti-tumor properties of this immune-enhancing skin microbiota strain. A series of ex vivo and in vivo experiments were conducted to assess immune cell proliferation, cytokine production, and anti-tumor efficacy. In ex vivo studies, splenocytes treated with the bacterial lysate or culture supernatant of the strain showed significantly increased viability in a concentration-dependent manner. Flow cytometry analysis revealed increased populations of dendritic cells, NK cells (Natural killer cells), and γδ T cells, with enhanced cytokine production, particularly IFN-γ (Interferon-γ) and perforin, in the lysate-treated group. When administered via intraperitoneal and intravenous routes in vivo, mice showed significant inhibition of melanoma growth upon receiving the bacterial lysate. Notably, pre-treatment demonstrated superior efficacy compared to post-treatment. Furthermore, the combination of the bacterial lysate with anti-PD-1 (anti-Programmed cell death protein-1) monoclonal antibody further suppressed tumor growth compared to anti-PD-1 monotherapy. These findings suggest that the AIT01 lysate enhances immune cell proliferation and cytokine production, contributing to its potent anti-tumor effects. The systemic delivery of this immune-boosting skin microbiota strain, particularly in combination with anti-PD-1 therapy, holds promise as an effective immunotherapeutic strategy against melanoma.

Beyond supporting cancer cell proliferation, tumor growth relies on the ability of cancer cells to evade immune surveillance. Identifying novel molecules that promote tumor immune escape may help develop more effective immunotherapeutic strategies. The histone acetyltransferase E1A-binding protein p300 (EP300) is a key epigenetic regulator that modulates gene transcription through chromatin remodeling and acetylation of histones and transcription factors. However, its role in regulating immune evasion remains incompletely understood. This study investigates the impact of EP300 on tumor immune escape and suggests its potential as an immunotherapeutic target.

Patients with non-small cell lung cancer (NSCLC) with loss of the tumor suppressor gene STK11 are resistant to immune checkpoint therapies like anti-PD-1. In this study, we conducted an in vivo CRISPR screen that identified histone deacetylase 1 as a target to reverse anti-PD-1 resistance driven by loss of STK11 and developed TNG260, a potent small-molecule inhibitor of the CoREST complex with selectivity exceeding previously generated inhibitors in this class in preclinical studies. Treatment with TNG260 led to increased expression of immunomodulatory genes in STK11-deficient cancer cells. When combined with anti-PD-1, TNG260 induced immune-mediated stasis and/or regression in STK11-deficient syngeneic tumor models and autochthonous NSCLC models. In the tumors of patients with STK11-deficient cancers in a clinical trial (NCT05887492), treatment with a combination of TNG260 and pembrolizumab increased intratumoral histone acetylation, PD-L1 tumor proportion scores, and T-cell infiltration into the tumor microenvironment. This study illustrates a promising treatment strategy for addressing immune evasion in patients with STK11-mutant NSCLC.

Talc pleurodesis is highly effective for preventing recurrence of pneumothorax and pleural effusion, but it can be complicated by dissemination, acute lung injury, lead exposure, and foreign body-induced chronic inflammation and pain. Our objective is to develop a safe, biodegradable, contaminant-free particle for pleurodesis. We used mouse models of pneumothorax and malignant pleural effusion to compare the efficacy and safety of pleurodesis with talc and hydroxyapatite microspheres (HAM). Intrapleural instillation of microspheres induced pleural adhesions, fibrosis, and symphysis as effectively as talc and resulted in more durable protection from experimental pneumothorax. HAM and talc both induced an osteoclastogenic, inflammatory, and fibrotic response in pleural lavage cells. Intrapleural HAM was resorbed by osteoclast action over 3 months, whereas talc was not cleared. Deletion of the osteoclast effector, CTSK, diminished pleural adhesion formation and fibrosis by HAM, and inhibition of osteoclastogenesis with anti-RANKL antibody delayed HAM clearance. We found no difference in activity level, feeding behavior, or lung compliance between particles, but talc induced more persistent pleural inflammation. We conclude that HAM resulted in an osteoclastogenic and fibrogenic pleural response that induced pleurodesis that was more durable than talc with a superior safety profile due in part to osteoclast-mediated particle clearance.

Leptomeningeal disease (LMD) is a subtype of central nervous system metastatic disease that is associated with poor patient outcomes and limited treatment options. There is an unmet need to develop preclinical models of LMD to expedite and improve the development of new therapeutics. Here, we describe the development of multiple orthotopic immunocompetent murine models of melanoma LMD, including their use to assess the efficacy of systemic and/or intrathecal immunotherapy. LMD was established by direct intrathecal injection of murine cell lines (B16-F10, BP, D4M, D4M-UV2, MC38-gp100, RMS, YUMM3.1, and YUMMER1.7) into the cisterna magna of C57BL/6 mice. Tumor take rate, distribution, histology, peri-procedural mortality, and animal survival were assessed for each cell line. Intrathecal and systemic treatment with anti-PD1 were tested for safety, efficacy, and immune infiltration for LMD. Cisternal injection of murine melanoma cell lines successfully established LMD with low peri-procedural mortality, high tumor take rate, and varied survival duration across the panel of cell lines. Decreasing the total number of cells injected and increasing the volume of suspension of the injected cells increased the rate of distal spinal cord deposits, reflecting the common clinical distribution of LMD. Intrathecal administration of anti-PD1 in non-tumor bearing mice caused no morbidity or toxicity. Concurrent intrathecal and systemic anti-PD1 immunotherapy increased the survival of mice with murine melanoma LMD. We have established and characterized several immunocompetent murine models of LMD to facilitate the development and testing of new, more effective immunotherapy strategies for melanoma patients with LMD.

Perineural invasion (PNI) is a well-established factor of poor prognosis in multiple cancer types1, yet its mechanism remains unclear. Here we provide clinical and mechanistic insights into the role of PNI and cancer-induced nerve injury (CINI) in resistance to anti-PD-1 therapy. Our study demonstrates that PNI and CINI of tumour-associated nerves are associated with poor response to anti-PD-1 therapy among patients with cutaneous squamous cell carcinoma, melanoma and gastric cancer. Electron microscopy and electrical conduction analyses reveal that cancer cells degrade the nerve fibre myelin sheets. The injured neurons respond by autonomously initiating IL-6- and type I interferon-mediated inflammation to promote nerve healing and regeneration. As the tumour grows, the CINI burden increases, and its associated inflammation becomes chronic and skews the general immune tone within the tumour microenvironment into a suppressive and exhaustive state. The CINI-driven anti-PD-1 resistance can be reversed by targeting multiple steps in the CINI signalling process: denervating the tumour, conditional knockout of the transcription factor mediating the injury signal within neurons (Atf3), knockout of interferon-α receptor signalling (Ifnar1-/-) or by combining anti-PD-1 and anti-IL-6-receptor blockade. Our findings demonstrate the direct immunoregulatory roles of CINI and its therapeutic potential.

Eps15 homology domain (EHD) proteins, including EHD1 to EHD4, play vital roles in tumor progression. In this study, we aimed to investigate which specific EHD proteins, if any, are implicated in tumor immune evasion and immunotherapy response.

Type 1 diabetes (T1D) is characterised by the autoimmune-mediated destruction of pancreatic β-cells. Although traditionally viewed as a disease dominated by T cells, recent studies have emphasised the crucial role of B cells in the development of T1D. Genome-wide association studies (GWAS) have revealed that CD226 is related to susceptibility to several autoimmune diseases, including T1D. Our recent work identified a pathogenic role of CD226+ CD8+ T cells in T1D. However, the involvement of CD226+ B cells in T1D development remains unclear.

Gut microbiota influence on the effectiveness of immune checkpoint inhibitors (ICIs), but research on fungi-an essential component of the microbiome-has been limited. This multi-cohort meta-analysis of 976 fecal metagenomes across 8 cohorts, representing melanoma, non-small cell lung cancer (NSCLC), and renal cell carcinoma (RCC), identified fungal species associated with ICI efficacy. In melanoma, Rhizophagus irregularis and Debaryomyces hansenii were correlated with poor responses, whereas Aspergillus avenaceus was associated with great efficacy. In NSCLC, an increased abundance of Aspergillus pseudonomiae was associated with a favorable prognosis. Stronger bacterial-fungal interactions were observed in responders. The presence of certain fungi in fungal enterotypes, like Aspergillus or Saccharomyces, was linked to better efficacy to ICIs. Mouse models revealed Debaryomyces hansenii impaired ICI efficacy by reducing CD8+ T cells. Our findings highlight specific fungal signatures that may inform strategies to enhance ICI efficacy and encourage further research on microbial impacts on treatment outcomes.

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.