Vasoactive intestinal peptide blockade suppresses tumor growth by regulating macrophage polarization and function in CT26 tumor-bearing mice

Decoding the neuroimmune axis in colorectal cancer: From neural circuitry to therapeutic innovation

The nervous and immune systems are two major components that maintain body homeostasis, with their functional roles often overlapping significantly. Both systems are capable of identifying, integrating, and organizing responsive reactions to various external stimuli. The gut, referred to as the "second brain" and the largest immune organ in the body, serves as the most frequent focal site for neuroimmune interactions. Colorectal cancer (CRC), as the predominant solid tumor arising in this neuroimmune-rich microenvironment, remains understudied through the lens of neuroimmune regulatory mechanisms. This review systematically synthesizes current evidence to elucidate the neuroimmune axis in CRC pathogenesis, with particular emphasis on neuroimmune crosstalk-mediated remodeling of tumor immunity. We comprehensively catalog the immunomodulatory effects exerted by principal neuroregulatory mediators, categorized as: (1) neurotransmitters (glutamate, glutamine, γ-aminobutyric acid, epinephrine, norepinephrine, dopamine, serotonin, acetylcholine, and gaseous signaling molecules); (2) neuropeptides (substance P, calcitonin gene-related peptide, vasoactive intestinal peptide); and (3) neurotrophic factors. Furthermore, we critically evaluate the translational prospects and therapeutic challenges of targeting neuroimmune pathways and propose strategic priorities and research focuses for advancing the development of neuroimmune interaction-related therapeutic approaches in CRC.

Antimicrobial Neuropeptides and Their Receptors: Immunoregulator and Therapeutic Targets for Immune Disorders

The interaction between the neuroendocrine system and the immune system plays a key role in the onset and progression of various diseases. Neuropeptides, recognized as common biochemical mediators of communication between these systems, are receiving increasing attention because of their potential therapeutic applications in immune-related disorders. Additionally, many neuropeptides share significant similarities with antimicrobial peptides (AMPs), and evidence shows that these antimicrobial neuropeptides are directly involved in innate immunity. This review examines 10 antimicrobial neuropeptides, including pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal peptide (VIP), α-melanocyte stimulating hormone (α-MSH), ghrelin, adrenomedullin (AM), neuropeptide Y (NPY), urocortin II (UCN II), calcitonin gene-related peptide (CGRP), substance P (SP), and catestatin (CST). Their expression characteristics and the immunomodulatory mechanisms mediated by their specific receptors are summarized, along with potential drugs targeting these receptors. Future studies should focus on further investigating antimicrobial neuropeptides and advancing the development of related drugs in preclinical and/or clinical studies to improve the treatment of immune-related diseases.

Identification of key regulators in pancreatic ductal adenocarcinoma using network theoretical approach

Pancreatic Ductal Adenocarcinoma (PDAC) is a devastating disease with poor clinical outcomes, which is mainly because of delayed disease detection, resistance to chemotherapy, and lack of specific targeted therapies. The disease's development involves complex interactions among immunological, genetic, and environmental factors, yet its molecular mechanism remains elusive. A major challenge in understanding PDAC etiology lies in unraveling the genetic profiling that governs the PDAC network. To address this, we examined the gene expression profile of PDAC and compared it with that of healthy controls, identifying differentially expressed genes (DEGs). These DEGs formed the basis for constructing the PDAC protein interaction network, and their network topological properties were calculated. It was found that the PDAC network self-organizes into a scale-free fractal state with weakly hierarchical organization. Newman and Girvan's algorithm (leading eigenvector (LEV) method) of community detection enumerated four communities leading to at least one motif defined by G (3,3). Our analysis revealed 33 key regulators were predominantly enriched in neuroactive ligand-receptor interaction, Cell adhesion molecules, Leukocyte transendothelial migration pathways; positive regulation of cell proliferation, positive regulation of protein kinase B signaling biological functions; G-protein beta-subunit binding, receptor binding molecular functions etc. Transcription Factor and mi-RNA of the key regulators were obtained. Recognizing the therapeutic potential and biomarker significance of PDAC Key regulators, we also identified approved drugs for specific genes. However, it is imperative to subject Key regulators to experimental validation to establish their efficacy in the context of PDAC.

Identification and characterization of vasoactive intestinal peptide receptor antagonists with high-affinity and potent anti-leukemia activity

Vasoactive intestinal peptide (VIP) is a neuropeptide involved in tumor growth and immune modulating functions. Previous research indicated that a VIP antagonist (VIPhyb) enhances T-cell activation and induces T-cell-dependent anti-leukemic activity in mice. We created a combinatorial library of VIPhyb C-terminal sequence variations to develop a more potent VIP-receptor (VIP-R) antagonist, hypothesizing that specific amino acid substitutions would improve receptor binding and plasma stability. In silico screening analyses identified sequences with improved docking scores predicting increased binding affinity to human VIP receptors VPAC1 and VPAC2. Fifteen peptides were synthesized and tested for their ability to potentiate activation of purified mouse and human T cells and enhance T cell-dependent anti-leukemia responses in murine models of acute myeloid leukemia. Treating C57Bl/6 mice engrafted with a C1498 myeloid leukemia cell line with daily subcutaneous injections of VIP-R antagonist peptides induced T cell activation resulting in specific anti-leukemia responses. Strikingly, the predicted binding affinity of the VIP-R antagonists to VIP receptors correlated positively with their ability to augment mouse T-cell proliferation and anti-leukemia activity. ANT308 and ANT195 emerged as top candidates due to their high predicted VIP-R binding, low EC 50 for in vitro T cell activation, and potent anti-leukemia activities. ANT308 decreased CREB phosphorylation, a downstream signaling pathway of the VIP receptor, and stimulated granzyme B and perforin expression in CD8+ T cells from AML patients. Combining in silico modeling, in vitro T cell activation properties, and in vivo anti-leukemia activity has identified promising VIP-R antagonist candidates for further development as novel immunotherapies for AML, especially for patients with relapsed disease.

VPAC2 Receptor Signaling Promotes Growth and Immunosuppression in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) harbors a complex tumor microenvironment, and cross-talk among cells in the tumor microenvironment can contribute to drug resistance and relapse. Vasoactive intestinal peptide (VIP) is overexpressed in PDAC, and VIP receptors expressed on T cells are a targetable pathway that sensitizes PDAC to immunotherapy. In this study, we showed that pancreatic cancer cells engage in autocrine VIP signaling through VIP receptor 2 (VPAC2). High coexpression of VIP with VPAC2 correlated with reduced relapse-free survival in patients with PDAC. VPAC2 activation in PDAC cells upregulated Piwi-like RNA-mediated gene silencing 2, which stimulated cancer cell clonogenic growth. In addition, VPAC2 signaling increased expression of TGFβ1 to inhibit T-cell function. Loss of VPAC2 on PDAC cells led to reduced tumor growth and increased sensitivity to anti-PD-1 immunotherapy in mouse models of PDAC. Overall, these findings expand our understanding of the role of VIP/VPAC2 signaling in PDAC and provide the rationale for developing potent VPAC2-specific antagonists for treating patients with PDAC. Significance: Autocrine VIP signaling via VPAC2 promotes cancer cell growth and inhibits T-cell function in pancreatic ductal adenocarcinoma, highlighting its potential as a therapeutic target to improve pancreatic cancer treatment.

Neuroimmune Crossroads: The Interplay of the Enteric Nervous System and Intestinal Macrophages in Gut Homeostasis and Disease

A defining unique characteristic of the gut immune system is its ability to respond effectively to foreign pathogens while mitigating unnecessary inflammation. Intestinal macrophages serve as the cornerstone of this balancing act, acting uniquely as both the sword and shield in the gut microenvironment. The GI tract is densely innervated by the enteric nervous system (ENS), the intrinsic nervous system of the gut. Recent advances in sequencing technology have increasingly suggested neuroimmune crosstalk as a critical component for homeostasis both within the gut and in other tissues. Here, we systematically review the ENS-macrophage axis. We focus on the pertinent molecules produced by the ENS, spotlight the mechanistic contributions of intestinal macrophages to gut homeostasis and inflammation, and discuss both existing and potential strategies that intestinal macrophages use to integrate signals from the ENS. This review aims to elucidate the complex molecular basis governing ENS-macrophage signaling, highlighting their cooperative roles in sustaining intestinal health and immune equilibrium.

Metabolic interplay: tumor macrophages and regulatory T cells

The tumor microenvironment (TME) contains a complex cellular ecosystem where cancer, stromal, vascular, and immune cells interact. Macrophages and regulatory T cells (Tregs) are critical not only for maintaining immunological homeostasis and tumor growth but also for monitoring the functional states of other immune cells. Emerging evidence reveals that metabolic changes in macrophages and Tregs significantly influence their pro-/antitumor functions through the regulation of signaling cascades and epigenetic reprogramming. Hence, they are increasingly recognized as therapeutic targets in cancer immunotherapy. Specific metabolites in the TME may also affect their pro-/antitumor functions by intervening with the metabolic machinery. We discuss how metabolites influence the immunosuppressive phenotypes of tumor-associated macrophages (TAMs) and Tregs. We then describe how TAMs and Tregs, independently or collaboratively, utilize metabolic mechanisms to suppress the activity of CD8+ T cells. Finally, we highlight promising metabolic interventions that can improve the outcome of current cancer therapies.

The VIPR2-selective antagonist KS-133 changes macrophage polarization and exerts potent anti-tumor effects as a single agent and in combination with an anti-PD-1 antibody

We have previously demonstrated that KS-133 is a specific and potent antagonist of vasoactive intestinal peptide receptor 2 (VIPR2). We have also shown that vasoactive intestinal peptide-VIPR2 signaling affects the polarity and activation of tumor-associated macrophages, which is another strategy for cancer immunotherapy apart from the activation of effector T cells. In this study, we aimed to examine whether the selective blockade of VIPR2 by KS-133 changes the polarization of macrophages and induces anti-tumor effects. In the presence of KS-133, genetic markers indicative of tumor-aggressive M1-type macrophages were upregulated, and conversely, those of tumor-supportive M2-type macrophages were downregulated. Daily subcutaneous administration of KS-133 tended to suppress the growth of CT26 tumors (murine colorectal cancer-derived cells) implanted subcutaneously in Balb/c mice. To improve the pharmacological efficacy and reduce the number of doses, we examined a nanoformulation of KS-133 using the US Food and Drug Administration-approved pharmaceutical additive surfactant Cremophor® EL. KS-133 nanoparticles (NPs) were approximately 15 nm in size and stable at 4°C after preparation. Meanwhile, KS-133 was gradually released from the NPs as the temperature was increased. Subcutaneous administration of KS-133 NPs once every 3 days had stronger anti-tumor effects than daily subcutaneous administration of KS-133. Furthermore, KS-133 NPs significantly enhanced the pharmacological efficacy of an immune checkpoint-inhibiting anti-PD-1 antibody. A pharmacokinetic study suggested that the enhancement of anti-tumor activity was associated with improvement of the pharmacokinetic profile of KS-133 upon nanoformulation. Our data have revealed that specific blockade of VIPR2 by KS-133 has therapeutic potential for cancer both alone and in combination with immune checkpoint inhibitors.

The magic of small-molecule drugs during ex vivo expansion in adoptive cell therapy

In the past decades, advances in the use of adoptive cellular therapy to treat cancer have led to unprecedented responses in patients with relapsed/refractory or late-stage malignancies. However, cellular exhaustion and senescence limit the efficacy of FDA-approved T-cell therapies in patients with hematologic malignancies and the widespread application of this approach in treating patients with solid tumors. Investigators are addressing the current obstacles by focusing on the manufacturing process of effector T cells, including engineering approaches and ex vivo expansion strategies to regulate T-cell differentiation. Here we reviewed the current small-molecule strategies to enhance T-cell expansion, persistence, and functionality during ex vivo manufacturing. We further discussed the synergistic benefits of the dual-targeting approaches and proposed novel vasoactive intestinal peptide receptor antagonists (VIPR-ANT) peptides as emerging candidates to enhance cell-based immunotherapy.