CCR8 leads to eosinophil migration and regulates neutrophil migration in murine allergic enteritis

CCR8 antagonist suppresses liver cancer progression via turning tumor-infiltrating Tregs into less immunosuppressive phenotype

BACKGROUND

Regulatory T cells (Tregs) are the main immunosuppressive cells in tumor immune microenvironment (TIME). However, systemic Treg depletion is not favored due to the crucial role of Tregs in the maintenance of immune homeostasis and prevention of autoimmunity. Recently, CCR8 has been identified as a key chemokine receptor expressed on tumor-infiltrating Tregs and targeted blockade of CCR8 exerts anticancer effect in several cancer types, but whether this pathway is involved in the progression of hepatocellular carcinoma (HCC) remains unclear.

METHODS

We determined the involvement of CCR8+ Tregs in HCC using human HCC tissues and TCGA database, and examined the anticancer effect and the underlying molecular mechanisms of the CCR8 antagonist, IPG0521m, which was developed in house, in murine liver cancer model with flow cytometry, bulk and single-cell RNA sequencing and Real-Time PCR.

RESULTS

Remarkable increase in CCR8+ Tregs was observed in human HCC tissues. Treatment of syngeneic liver cancer model with IPG0521m resulted in dramatic inhibition of tumor growth, associated with increased CD8+ T cells in tumor tissues. Bulk RNA sequencing analysis indicated that IPG0521m treatment resulted in remarkable increase in antitumor immunity. Furthermore, single-cell RNA sequencing analysis demonstrated that IPG0521m treatment resulted in a switch of Tregs from high immunosuppression to low immunosuppression phenotype, associated with elevated CD8+ T and NK cell proliferation and cytotoxicity, and decreased myeloid-derived suppressor cells and tumor-associated macrophages in the tumor tissues.

CONCLUSIONS

IPG0521m inhibited liver cancer growth via reducing the immunosuppressive function of Tregs, thereby boosting anti-cancer immunity. Our study paves the way for the clinical study of CCR8 antagonist in HCC and other cancers.

Dietary fiber pectin alters the gut microbiota and diminishes the inflammatory immune responses in an experimental peach allergy mouse model

Since therapeutic options are limited the utilization of prebiotics is suggested to prevent food allergies (FAs). Using an experimental peach allergy model we explored the effect of dietary fiber pectin, a high-methoxyl heteropolysaccharide, on the manifestation of FA. CBA/J mice were sensitized, subsequently orally boosted and provoked with peach peel extract. For dietary intervention, mice were fed a pectin containing diet before (primary-preventive) or after (secondary-preventive) sensitization. Non-treated allergic and sham-treated mice were fed a diet containing 20% cellulose. Fecal microbiota, humoral and intestinal immune cell responses were analyzed. Pectin remarkably affected the gut microbiota composition and diversity, promoting mainly the growth of Bacteroides. The frequency of mast cells, macrophages, and CD3+T cells in the lamina propria of the small intestine was reduced, whereas the frequency of B cells and CD4+T cell subpopulation was enhanced. Pectin intervention in the primary-preventive stetting significantly triggered serum IgA levels, whereas production of IgE and mMCPT-1 was reduced. Remarkably, in both settings peach allergen-specific IgG1/IgG2a ratio and specific IgE were significantly reduced to baseline. The data suggest, that dietary supplementation of pectin in both intervention approaches can diminish inflammatory responses and signs of allergic immune responses, accompanied by alteration of the gut microbiota composition.

Maternal exposure to 4-tert-octylphenol causes alterations in the morphology and function of microglia in the offspring mouse brain

4-tert-Octylphenol (OP), an endocrine disrupting chemical is widely used in the production of industrial products. Prenatal exposure to endocrine-disrupting chemicals negatively affects the brain. However, the influence of OP exposure during neurodevelopment in adult offspring remains unclear. Thus, in the present study, we investigated the effects of maternal OP exposure on brain development in adult offspring by analyzing primary glial cell cultures and mice. Our findings revealed that OP exposure led to a specific increase in the mRNA expression of the ionized calcium-binding adapter molecule 1 (Iba-1) and the proportion of amoeboid microglia in the primary glial cell culture and adult offspring mice. Exposure to OP increased the transcriptional activation of Iba-1 and estrogen response element, which were counteracted by estrogen receptor antagonists ICI 182,780. Moreover, OP exposure increased the nuclear localization of the estrogen receptor. Remarkably, OP exposure decreased the mRNA expression levels of proinflammatory cytokines and genes associated with immune response in the brains of the offspring. OP exposure upregulated actin filament-related genes and altered cytoskeletal gene expression, as demonstrated by microarray analysis. The morphological changes in microglia did not result in an inflammatory response following lipopolysaccharide treatment. Taken together, the effects of OP exposure during neurodevelopment persist into adulthood, resulting in microglial dysfunction mediated by estrogen receptor signaling pathways in the brains of adult offspring mice.

CC Chemokine Family Members' Modulation as a Novel Approach for Treating Central Nervous System and Peripheral Nervous System Injury-A Review of Clinical and Experimental Findings

Despite significant progress in modern medicine and pharmacology, damage to the nervous system with various etiologies still poses a challenge to doctors and scientists. Injuries lead to neuroimmunological changes in the central nervous system (CNS), which may result in both secondary damage and the development of tactile and thermal hypersensitivity. In our review, based on the analysis of many experimental and clinical studies, we indicate that the mechanisms occurring both at the level of the brain after direct damage and at the level of the spinal cord after peripheral nerve damage have a common immunological basis. This suggests that there are opportunities for similar pharmacological therapeutic interventions in the damage of various etiologies. Experimental data indicate that after CNS/PNS damage, the levels of 16 among the 28 CC-family chemokines, i.e., CCL1, CCL2, CCL3, CCL4, CCL5, CCL6, CCL7, CCL8, CCL9, CCL11, CCL12, CCL17, CCL19, CCL20, CCL21, and CCL22, increase in the brain and/or spinal cord and have strong proinflammatory and/or pronociceptive effects. According to the available literature data, further investigation is still needed for understanding the role of the remaining chemokines, especially six of them which were found in humans but not in mice/rats, i.e., CCL13, CCL14, CCL15, CCL16, CCL18, and CCL23. Over the past several years, the results of studies in which available pharmacological tools were used indicated that blocking individual receptors, e.g., CCR1 (J113863 and BX513), CCR2 (RS504393, CCX872, INCB3344, and AZ889), CCR3 (SB328437), CCR4 (C021 and AZD-2098), and CCR5 (maraviroc, AZD-5672, and TAK-220), has beneficial effects after damage to both the CNS and PNS. Recently, experimental data have proved that blockades exerted by double antagonists CCR1/3 (UCB 35625) and CCR2/5 (cenicriviroc) have very good anti-inflammatory and antinociceptive effects. In addition, both single (J113863, RS504393, SB328437, C021, and maraviroc) and dual (cenicriviroc) chemokine receptor antagonists enhanced the analgesic effect of opioid drugs. This review will display the evidence that a multidirectional strategy based on the modulation of neuronal-glial-immune interactions can significantly improve the health of patients after CNS and PNS damage by changing the activity of chemokines belonging to the CC family. Moreover, in the case of pain, the combined administration of such antagonists with opioid drugs could reduce therapeutic doses and minimize the risk of complications.

Investigation of gut microbiota changes and allergic inflammation of mice with milk protein-induced allergic enteritis

This study aimed to investigate the changes of gut microbiota and allergic inflammation in mice with allergic enteritis caused by milk protein. In this study, female BALB\C mice in the whey protein (WP-sensitized) group were gavaged with WP and normal saline, the sham-sensitized group was given normal saline once a week for 5 weeks. One week later, the WP-sensitized mice were administered 60 mg β-lactoglobulin (BLG). The results showed that mice's body weight decreased, feces with loose and bloody, and systemic allergic reactions and ear swelling increased in the WP-sensitized group. The levels of WP-specific Ig, mMCP-1, calprotectin of feces, and inflammation-related factors in the WP-sensitized group were increased. WP-sensitized group intestine tissues were damaged severely and the expressions of ZO-1, Claudin-1, and Occludin reduced. The results of 16S rRNA sequencing showed that there were differences in operational taxonomic units (OUT) levels of gut microbes between the two groups, o_Clostridiales, c_Clostridia, and f_Lachnospiraceae were more abundant in the WP-sensitized group. In conclusion, the WP sensitization can induce the allergic inflammation, intestinal injury and intestinal barrier dysfunction in mice, and the gut microbes were also changed, which provided a reference for the treatment of WP-sensitized mice.

Selective reprogramming of regulatory T cells in solid tumors can strongly enhance or inhibit tumor growth

Folate receptor delta (FRδ) has been used as a biomarker for regulatory T cells (Tregs), because its expression is limited to Tregs and ovum. Although FRδ is unable to bind folate, we have used molecular docking software to identify a folate congener that binds FRδ with high affinity and have exploited this FRδ-specific ligand to target attached drugs (imaging agents, immune activators, and immune suppressors) specifically to Tregs in murine tumor xenografts. Analysis of treated tumors demonstrates that targeting of a Toll-like receptor 7 agonist inhibits Treg expression of FOXP3, PD-1, CTLA4, and HELIOS, resulting in 40-80% reduction in tumor growth and repolarization of other tumor-infiltrating immune cells to more inflammatory phenotypes. Targeting of the immunosuppressive drug dexamethasone, in contrast, promotes enhanced tumor growth and shifts the tumor-infiltrating immune cells to more anti-inflammatory phenotypes. Since Tregs comprise <1% of cells in the tumor masses examined, and since the targeted drugs are not internalized by cancer cells, these data demonstrate that Tregs exert a disproportionately large effect on tumor growth. Because the targeted drug did not bind to Tregs or other immune cells in healthy tissues, the data demonstrate that the immunosuppressive properties of Tregs in tumors can be manipulated without causing systemic toxicities associated with global reprogramming of the immune system.

Development of an Anti-Mouse CCR8 Monoclonal Antibody (C8Mab-1) for Flow Cytometry and Immunocytochemistry

It has been widely accepted that monoclonal antibody (mAb) is an effective tool for cancer immunotherapy. The C-C motif chemokine receptor 8 (CCR8) is highly expressed in regulatory T cells and many cancers and is associated with the progression of the cancers. However, its role in cancer progression remains unclear. Thus, the development of mAbs for CCR8 leads to cancer immunotherapy and elucidation of unknown mechanisms of CCR8-dependent cancer progression. In this study, we have developed an anti-mouse CCR8 (mCCR8) mAb (clone C₈Mab-1, rat IgG_2a, kappa) using the Cell-Based Immunization and Screening (CBIS) method. We showed that C₈Mab-1 and its recombinant antibody (recC₈Mab-1) bind to mCCR8-overexpressed Chinese hamster ovary (CHO)-K1 cells (CHO/mCCR8), but not to the parental CHO-K1 cells, in flow cytometry and immunofluorescence. Moreover, C₈Mab-1 and recC₈Mab-1 specifically reacted to P388 (a mouse lymphocyte-like cells) and J774-1 (a mouse macrophage-like cells), which express endogenous mCCR8, in both applications. These results suggest that C₈Mab-1, developed using the CBIS method, is useful for flow cytometry and immunocytochemistry against exogenous and endogenous mCCR8.

Resveratrol Treatment Prevents Increase of Mast Cells in Both Murine OVA Enteritis and IL-10-/- Colitis

Mast cells are involved in allergic and other inflammatory diseases. The polyphenol resveratrol is known for its anti-inflammatory properties and may be used as nutraceutical in mast cell associated diseases. We analyzed the effect of resveratrol on mast cells in vivo in ovalbumin-induced allergic enteritis as well as experimental colitis in IL-10^−/− mice which received resveratrol via drinking water. Treatment with resveratrol prevented the increase in mast cells in both allergic enteritis and chronic colitis in duodenum as well as in colon. Further, it delayed the onset of diseases symptoms and ameliorated diseases associated parameters such as tissue damage as well as inflammatory cell infiltration in affected colon sections. In addition to the findings in vivo, resveratrol inhibited IgE-dependent degranulation and expression of pro-inflammatory cytokines such as TNF-α in IgE/DNP-activated as well as in LPS-activated bone marrow-derived mast cells. These results indicate that resveratrol may be considered as an anti-allergic and anti-inflammatory plant-derived component for the prevention or treatment of mast cell-associated disorders of the gastrointestinal tract.

Chemokine Receptor-Targeted Therapies: Special Case for CCR8

Immune checkpoint blockade inhibitors (CBIs) targeting cytotoxic T lymphocyte associated protein-4 (CTLA-4) and program death receptor-1 (PD-1) or its ligand-1 (PD-L1) have transformed the outlook of many patients with cancer. This remarkable progress has highlighted, from the translational point of view, the importance of immune cells in the control of tumor progression. There is still room for improvement, since current CBI therapies benefit a minority of patients. Moreover, interference with immune checkpoint receptors frequently causes immune related adverse events (irAEs) with life-threatening consequences in some of the patients. Immunosuppressive cells in the tumor microenvironment (TME), including intratumoral regulatory T (Treg) cells, tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), contribute to tumor progression and correlate with a negative disease outlook. Recent reports revealed the selective expression of the chemokine receptor CCR8 on tumor Treg cells, making CCR8 a promising target in translational research. In this review, I summarize our current knowledge about the cellular distribution and function of CCR8 in physiological and pathophysiological processes. The discussion includes an assessment of how the removal of CCR8-expressing cells might affect both anti-tumor immunity as well as immune homeostasis at remote sites. Based on these considerations, CCR8 appears to be a promising novel target to be considered in future translational research.

Non-IgE-Mediated Gastrointestinal Food Protein-Induced Allergic Disorders. Clinical Perspectives and Analytical Approaches

Non-IgE-mediated gastrointestinal food allergy (non-IgE-GI-FA) is the name given to a series of pathologies whose main entities are food protein-induced allergic proctocolitis (FPIAP), food protein-induced enteropathy (FPE), and food protein-induced enterocolitis syndrome (FPIES). These are more uncommon than IgE-mediated food allergies, their mechanisms remain largely unknown, and their diagnosis is mainly done by clinical history, due to the lack of specific biomarkers. In this review, we present the latest advances found in the literature about clinical aspects, the current diagnosis, and treatment options of non-IgE-GI-FAs. We discuss the use of animal models, the analysis of gut microbiota, omics techniques, and fecal proteins with a focus on understanding the pathophysiological mechanisms of these pathologies and obtaining possible diagnostic and/or prognostic biomarkers. Finally, we discuss the unmet needs that researchers should tackle to advance in the knowledge of these barely explored pathologies.

PET Imaging Radiotracers of Chemokine Receptors

Chemokines and chemokine receptors have been recognized as critical signal components that maintain the physiological functions of various cells, particularly the immune cells. The signals of chemokines/chemokine receptors guide various leukocytes to respond to inflammatory reactions and infectious agents. Many chemokine receptors play supportive roles in the differentiation, proliferation, angiogenesis, and metastasis of diverse tumor cells. In addition, the signaling functions of a few chemokine receptors are associated with cardiac, pulmonary, and brain disorders. Over the years, numerous promising molecules ranging from small molecules to short peptides and antibodies have been developed to study the role of chemokine receptors in healthy states and diseased states. These drug-like candidates are in turn exploited as radiolabeled probes for the imaging of chemokine receptors using noninvasive in vivo imaging, such as positron emission tomography (PET). Recent advances in the development of radiotracers for various chemokine receptors, particularly of CXCR4, CCR2, and CCR5, shed new light on chemokine-related cancer and cardiovascular research and the subsequent drug development. Here, we present the recent progress in PET radiotracer development for imaging of various chemokine receptors.

Understanding and Targeting Human Cancer Regulatory T Cells to Improve Therapy

Regulatory T cells (Tregs) are critical in maintaining immune homeostasis under various pathophysiological conditions. A growing body of evidence demonstrates that Tregs play an important role in cancer progression and that they do so by suppressing cancer-directed immune responses. Tregs have been targeted for destruction by exploiting antibodies against and small-molecule inhibitors of several molecules that are highly expressed in Tregs-including immune checkpoint molecules, chemokine receptors, and metabolites. To date, these strategies have had only limited antitumor efficacy, yet they have also created significant risk of autoimmunity because most of them do not differentiate Tregs in tumors from those in normal tissues. Currently, immune checkpoint inhibitor (ICI)-based cancer immunotherapies have revolutionized cancer treatment, but the resistance to ICI is common and the elevation of Tregs is one of the most important mechanisms. Therapeutic strategies that can selectively eliminate Tregs in the tumor (i.e. therapies that do not run the risk of causing autoimmunity by affecting normal tissue), are urgently needed for the development of cancer immunotherapies. This chapter discusses specific properties of human Tregs under the context of cancer and the various ways to target Treg for cancer immunotherapy.

Biased agonism at chemokine receptors

In the human chemokine system, interactions between the approximately 50 known endogenous chemokine ligands and 20 known chemokine receptors (CKRs) regulate a wide range of cellular functions and biological processes including immune cell activation and homeostasis, development, angiogenesis, and neuromodulation. CKRs are a family of G protein-coupled receptors (GPCR), which represent the most common and versatile class of receptors in the human genome and the targets of approximately one third of all Food and Drug Administration-approved drugs. Chemokines and CKRs bind with significant promiscuity, as most CKRs can be activated by multiple chemokines and most chemokines can activate multiple CKRs. While these ligand-receptor interactions were previously regarded as redundant, it is now appreciated that many chemokine:CKR interactions display biased agonism, the phenomenon in which different ligands binding to the same receptor signal through different pathways with different efficacies, leading to distinct biological effects. Notably, these biased responses can be modulated through changes in ligand, receptor, and or the specific cellular context (system). In this review, we explore the biochemical mechanisms, functional consequences, and therapeutic potential of biased agonism in the chemokine system. An enhanced understanding of biased agonism in the chemokine system may prove transformative in the understanding of the mechanisms and consequences of biased signaling across all GPCR subtypes and aid in the development of biased pharmaceuticals with increased therapeutic efficacy and safer side effect profiles.