Tolerogenic properties of CD206+ macrophages appeared in the sublingual mucosa after repeated antigen-painting

The pathogenic role of retinoid nuclear receptor signaling in cancer and metabolic syndromes

The retinoid nuclear receptor pathway, activated by the vitamin A metabolite retinoic acid, has been extensively investigated for over a century. This study has resulted in conflicting hypotheses about how the pathway regulates health and how it should be pharmaceutically manipulated. These disagreements arise from a fundamental contradiction: retinoid agonists offer clear benefits to select patients with rare bone growth disorders, acute promyelocytic leukemia, and some dermatologic diseases, yet therapeutic retinoid pathway activation frequently causes more harm than good, both through acute metabolic dysregulation and a delayed cancer-promoting effect. In this review, we discuss controlled clinical, mechanistic, and genetic data to suggest several disease settings where inhibition of the retinoid pathway may be a compelling therapeutic strategy, such as solid cancers or metabolic syndromes, and also caution against continued testing of retinoid agonists in cancer patients. Considerable evidence suggests a central role for retinoid regulation of immunity and metabolism, with therapeutic opportunities to antagonize retinoid signaling proposed in cancer, diabetes, and obesity.

Divergent Processing of Cell Stress Signals as the Basis of Cancer Progression: Licensing NFκB on Chromatin

Inflammation is activated by diverse triggers that induce the expression of cytokines and adhesion molecules, which permit a succession of molecules and cells to deliver stimuli and functions that help the immune system clear the primary cause of tissue damage, whether this is an infection, a tumor, or a trauma. During inflammation, short-term changes in the expression and secretion of strong mediators of inflammation occur, while long-term changes occur to specific groups of cells. Long-term changes include cellular transdifferentiation for some types of cells that need to regenerate damaged tissue, as well as death for specific immune cells that can be detrimental to tissue integrity if they remain active beyond the boundaries of essential function. The transcriptional regulator NFκB enables some of the fundamental gene expression changes during inflammation, as well as during tissue development. During recurrence of malignant disease, cell stress-induced alterations enable the growth of cancer cell clones that are substantially resistant to therapeutic intervention and to the immune system. A number of those alterations occur due to significant defects in feedback signal cascades that control the activity of NFκB. Specifically, cell stress contributes to feedback defects as it overrides modules that otherwise control inflammation to protect host tissue. NFκB is involved in both the suppression and promotion of cancer, and the key distinctive feature that determines its net effect remains unclear. This paper aims to provide a clear answer to at least one aspect of this question, namely the mechanism that enables a divergent response of cancer cells to critical inflammatory stimuli and to cell stress in general.

PCLLA-nanoHA Bone Substitute Promotes M2 Macrophage Polarization and Improves Alveolar Bone Repair in Diabetic Environments

The utilization of bioresorbable synthetic bone substitutes with immunomodulatory properties has gained significant attention in dental clinical applications for the absorption of alveolar bone induced by orthodontic treatment. In this study, we developed two distinct materials: a conventional hydroxyapatite (HA) bone powder comprised of hydroxyapatite particles and nanoHA embedded within a poly(caprolactone-co-lactide) (PCLLA) elastomeric matrix. We assessed the physicochemical characteristics of the bone substitute, specifically focusing on its composition and the controlled release of ions. Our findings show that PCLLA-nanoHA has deformable properties under 40 N, and a significant release of Ca and P elements was noted after 7 days in aqueous settings. Moreover, at the protein and gene expression levels, PCLLA-nanoHA enhances the capacity of macrophages to polarize towards an M2 phenotype in vitro. In vivo, PCLLA-nanoHA exhibits comparable effects to standard HA bone powder in terms of promoting alveolar bone regeneration. Extensive investigations reveal that PCLLA-nanoHA surpasses the commonly employed HA bone powder in stimulating bone tissue repair in diabetic mice. We have identified that PCLLA-nanoHA regulates macrophage M2 polarization by activating the PI3K/AKT and peroxisome proliferator-activated receptor gamma (PPAR) signaling pathways, thereby facilitating a favorable local immune microenvironment conducive to bone repair and regeneration. Our findings suggest that PCLLA-nanoHA presents itself as a promising bioresorbable bone substitute with properties that promote macrophage M2 polarization, particularly in the context of regulating the local microenvironment of alveolar bone in diabetic mice, potentially facilitating bone tissue regeneration.

Engineered Apoptosis-Bioinspired Nanoparticles Initiate Immune Cascade for Cancer Immunotherapy of Malignant Ascites

Malignant ascites (MA) is a common symptom of peritoneal metastasis in liver cancer. Cancer immunotherapy can modulate immune cells to induce antitumor immune efficiency. Reprogramming tumor immune microenvironment (TIME) is a momentous strategy to overcome immunosuppression and achieve immune functional normalization. Inspired by the inherent apoptotic bodies and vesicles, we proposed and systematically studied engineered apoptosis-bioinspired nanoparticles (EBN) for cancer immunotherapy of MA. Using both in vitro and in vivo experimental validations, we elucidated that EBN could be efficiently engulfed by the tumor-associated macrophages (TAMs) and manipulate their polarization. Moreover, a boosted immune cascade response as a result of heightening cytotoxic T-lymphocytes (CTLs) activity was investigated. Based on these results, EBN was confirmed to have strong immune cascade activation capability. Remarkably, the injection of EBN further reduced ascites volume and reformed immune cell subtypes, compared to the injection of either PBS or free TMP195 alone. In short, this novel nanodrug delivery system (NDDS) represents a prospective immunotherapeutic approach for clinical therapeutics of hepatoma ascites and other malignant effusion.

Hapten sensitization to vaginal mucosa induces less recruitment of dendritic cells accompanying TGF-β-expressing CD206+ cells compared with skin

INTRODUCTION

Contact hypersensitivity (CHS), a type of delayed-type hypersensitivity, is induced by hapten exposure to the skin and mucosa. We previously reported that, in a murine model of CHS, the vaginal mucosa (VM) sensitization showed lower T-cell responses as compared with the abdominal skin sensitization. To investigate mechanisms of impaired CHS by the VM sensitization, we compared migration of hapten-captured dendritic cells (DCs) in the draining lymph nodes (dLNs) and recruitment of DCs at the sensitized local sites.

METHODS

Fluorescein isothiocyanate (FITC) or 2,4-dinitrofluorobenzene (DNFB) was used as hapten, and migration of FITC+ DCs in the dLNs and local recruitment of MHC class II+ and CD11c+ cells were compared between abdominal skin and VM sensitization by flow cytometric analyses and immunohistochemistry. Expression of tumor growth factor (TGF)-β at mRNA and protein levels, and local recruitment of CD206+ cells were examined after VM sensitization.

RESULTS

VM sensitization showed less numbers of FITC+ MHC class IIhigh CD11c+ migratory DCs in the dLNs at 6 and 24 h, as compared with skin sensitization. Both skin and VM sensitization induced the recruitment of dermal/submucosal DCs at 6 h, but the number of submucosal DCs in the VM was significantly decreased at 24 h. VM showed persistently higher mRNA levels of TGF-β2/β3 expression than those of the skin before and after sensitization. In the VM sensitization, increment of CD206+ MHC class II+ cells was observed especially at the deep lamina propria at 24 h. Most of CD206+ cells were also positive for the binding to Fc chimeric TGF-β receptor that interacts with all TGF-β isoforms, suggesting TGF-β expression.

CONCLUSION

DC migration to dLNs and localization of DCs at the sensitized sites are limited in the VM sensitization. Our results suggest that the existence of TGF-β-expressing CD206+ cells may contribute less sensitization ability and CHS responses in the VM.

Polymorphonuclear Myeloid-Derived Cells That Contribute to the Immune Paralysis Are Generated in the Early Phase of Sepsis via PD-1/PD-L1 Pathway

Immune paralysis is a protracted state of immune suppression following the early/acute inflammatory phase of sepsis. CD11b⁺ Gr-1⁺ cells induced during sepsis are heterogeneous myeloid-derived cells (MDCs). This study investigated the contribution of MDCs to immune paralysis. Treatment of mice with zymosan (ZM) induced a marked increase in the total number of splenocytes with an increase in the proportion of Gr-1^hi cells and a decrease in the proportion of T cells on day 7; levels of these cells eventually return to levels similar to those of control mice on day 21. T-cell activation and gamma interferon (IFN-γ) expression by CD8⁺ T cells were clearly impaired in ZM-treated mice on day 21 (d21-ZM mice). Gr-1^hi cells showed a CD11b⁺ Ly6G^hi polymorphonuclear phenotype. Injection of lipopolysaccharide (LPS) into d21-ZM mice impaired interleukin 6 (IL-6) production in serum, accompanied by accumulation of CD11b⁺ Gr-1^hi cells in the peripheral blood. Transfer of Gr-1^hi cells from d21-ZM mice into intact mice impaired IL-6 production, but similar transfer of Gr-1^hi cells from PD-1/PD-L1-deficient d21-ZM mice showed no such suppressive effect. Conversely, either depletion of Gr-1^hi cells by treatment with anti-Gr-1 monoclonal antibody (MAb) or neutralization of the PD-1/PD-L1 pathway by anti-PD-1 and anti-PD-L1 MAbs during the induction phase of sepsis ameliorated ZM-induced immune suppression. Our results suggest that the PD-1/PD-L1-mediated generation of Gr-1^hi cells in the early phase of sepsis is required for the late phase of immune paralysis.

Sublingual Immunotherapy: How Sublingual Allergen Administration Heals Allergic Diseases; Current Perspective about the Mode of Action

Owing to the successful application of sublingual immunotherapy (SLIT), allergen immunotherapy (AIT) has become one of the leading treatments for allergic diseases. Similar to the case with other AITs, such as subcutaneous and oral immunotherapies, not only the alleviation of allergic symptoms, but also the curing of the diseases can be expected in patients undergoing SLIT. However, how and why such strong efficacy is obtained by SLIT, in which allergens are simply administered under the tongue, is not clearly known. Various potential mechanisms, including the induction of blocking antibodies, T cell tolerance, regulatory B and T cells, CD103^-CD11b⁺ classical dendritic cells, and CD206⁺ macrophages, and the reduction of innate lymphoid cells, mast cells, and basophils, have been suggested. Recently, through a comparative analysis between high- and non-responder patients of SLIT, we have successfully proposed several novel mechanisms. Here, we introduce our recent findings and summarize the current understanding of the mechanisms underlying the strong efficacy of SLIT.