Effects of Dendritic Cell Subset Manipulation on Airway Allergy in a Mouse Model

Long Non Coding RNA FOXD3‑AS1 Alleviates Allergic Rhinitis by Elevating the Th1/Th2 Ratio via the Regulation of Dendritic Cells

This article aimed to explore whether the regulation of Th1/Th2 immune responses by FOXD3-AS1 is associated with dendritic cells (DCs) in allergic rhinitis (AR). HE staining was performed to assess the pathological changes in the nasal mucosa; ELISA was performed to measure the levels of Th1/Th2-related cytokines; flow cytometry was performed to analyze Th1/Th2 cells and MHC-II-, CD80-, and CD86-positive DCs; and qRT‒PCR and western blotting were performed to measure mRNA and protein expression levels, respectively. Our data revealed that LV-FOXD3-AS1 improved AR and increased the Th1/Th2 cell ratio in AR model mice. LV-FOXD3-AS1 further inhibited DC maturation both in vivo and in vitro. Moreover, the coculture system of DCs and CD4+ T cells demonstrated that LV-FOXD3-AS1 increased the Th1/Th2 cell ratio by inhibiting the maturation of DCs. In addition, LV-FOXD3-AS1 reduced the level of phosphorylated STAT6 in DCs derived from healthy mice, and STAT6 overexpression eliminated the inhibitory effect of LV-FOXD3-AS1 on the maturation of DCs. In summary, LV-FOXD3-AS1 ameliorated AR by increasing the Th1/Th2 cell ratio by inhibiting DC maturation via the inhibition of STAT6 phosphorylation. Our data confirmed the protective effect of FOXD3-AS1 in AR and provided a novel idea for the treatment of this disease.

Dietary Omega-3 Fatty Acid Dampens Allergic Rhinitis via Eosinophilic Production of the Anti-Allergic Lipid Mediator 15-Hydroxyeicosapentaenoic Acid in Mice

The metabolism and generation of bioactive lipid mediators are key events in the exertion of the beneficial effects of dietary omega-3 fatty acids in the regulation of allergic inflammation. Here, we found that dietary linseed oil, which contains high amounts of alpha-linolenic acid (ALA) dampened allergic rhinitis through eosinophilic production of 15-hydroxyeicosapentaenoic acid (15-HEPE), a metabolite of eicosapentaenoic acid (EPA). Lipidomic analysis revealed that 15-HEPE was particularly accumulated in the nasal passage of linseed oil-fed mice after the development of allergic rhinitis with the increasing number of eosinophils. Indeed, the conversion of EPA to 15-HEPE was mediated by the 15-lipoxygenase activity of eosinophils. Intranasal injection of 15-HEPE dampened allergic symptoms by inhibiting mast cell degranulation, which was mediated by the action of peroxisome proliferator-activated receptor gamma. These findings identify 15-HEPE as a novel EPA-derived, and eosinophil-dependent anti-allergic metabolite, and provide a preventive and therapeutic strategy against allergic rhinitis.

A combination of check-point blockade and α-galactosylceramide elicits long-lasting suppressive effects on murine hepatoma cell growth in vivo

Immunotherapy for cancer cells induced by interfering with PD-1/PD-L1 engagement via check-point blockades was initiated by tumour-specific PD-1⁺ CD8⁺ cytotoxic T lymphocytes (CTLs) within a tumour mass and eliminate the tumour. Here, we used C57BL/6 (B6) mice implanted with the syngeneic hepatoma cell line Hepa1-6-1, and confirmed that the dendritic cells (DCs) within Hepa1-6-1 tumour mass were tolerogenic with downmodulated co-stimulatory molecules by tumour-derived factors. Although Hepa1-6-1 cells did not prime tumour-specific CTLs within the tumour, specific CTLs primed in the regional lymph nodes seemed to be invaded into the tumour mass. The specific CTLs gained PD-1⁺ expression when associated with PD-L1⁺ Hepa1-6-1 cells within the tumour mass. Their cytotoxic activity in vivo was revitalised after intraperitoneal (i.p.) administration of the anti-PD-1 monoclonal antibody (mAb), indicating that PD-1/PD-L1 engagement within the tumour was abrogated by check-point blockade. Nonetheless, the tolerogenic DCs within the Hepa1-6-1 tumour mass remained tolerogenic even after three shots of PD-1-blockade administration, and the suppressed Hepa1-6-1 growth was revisited. In this study, we show here an excellent therapeutic effect consisting of three injections of anti-PD1 mAb and the sequential administration of the CD1d molecule-restricted ligand α-galactosylceramide (α-GalCer), an immuno-potent lipid/glycolipid, which converts tolerogenic DCs into immunogenic DCs with upregulated expression of co-stimulatory molecules. The α-GalCer-activated DCs secreted a large amount of IL-12, which can activate tumour-specific CTLs in vivo. The check-point blockade was not sufficiently effective, but the dose needed for tumour eradication was reduced by 90% when tumour-bearing mice were also administered i.p. α-GalCer.

Differentiation of Langerhans Cells from Monocytes and Their Specific Function in Inducing IL-22-Specific Th Cells

Human mucosal tissues and skin contain two distinct types of dendritic cell (DC) subsets, epidermal Langerhans cells (LCs) and dermal DCs, which can be distinguished by the expression of C-type lectin receptors, Langerin and DC-SIGN, respectively. Although peripheral blood monocytes differentiate into these distinct subsets, monocyte-derived LCs (moLCs) induced by coculture with GM-CSF, IL-4, and TGF-β1 coexpress both Langerin and DC-SIGN, suggesting that the environmental cues remain unclear. In this study, we show that LC differentiation is TGF-β1 dependent and that cofactors such as IL-4 and TNF-α promote TGF-β1-dependent LC differentiation into Langerin+DC-SIGN- moLCs but continuous exposure to IL-4 blocks differentiation. Steroids such as dexamethasone greatly enhanced TNF-α-induced moLC differentiation and blocked DC-SIGN expression. Consistent with primary LCs, dexamethasone-treated moLCs express CD1a, whereas monocyte-derived DCs (moDCs) express CD1b, CD1c, and CD1d. moDCs but not moLCs produced inflammatory cytokines after stimulation with CD1b and CD1d ligands mycolic acid and α-galactosylceramide, respectively. Strikingly, CD1a triggering with squalene on moLCs but not moDCs induced strong IL-22-producing CD4+ helper T cell responses. As IL-22 is an important cytokine in the maintenance of skin homeostasis, these data suggest that CD1a on LCs is involved in maintaining the immune barrier in the skin.

Recent Advances in Experimental Allergy

Atopic disorders are on the rise and pose a great burden on society. A better understanding of the underlying mechanisms is required for the development of improved or novel therapeutic strategies. Here we aim to highlight recent advances in experimental allergy, with a particular focus on proposed treatment alternatives for airway disorders, atopic dermatitis, and food allergy. Furthermore, we discuss recent work focusing on molecular and cellular mechanisms that might offer candidates for future preventive or therapeutic intervention.

Suppression of murine tumour growth through CD8+ cytotoxic T lymphocytes via activated DEC-205+ dendritic cells by sequential administration of α-galactosylceramide in vivo

Cancer immunity is mediated through the effective priming and activation of tumour‐specific class I MHC molecule‐restricted CD8⁺ cytotoxic T lymphocytes (CTLs). DEC‐205⁺ dendritic cells (DCs) can cross‐present the epitope(s) of captured tumour antigens associated with class I MHC molecules alongside co‐stimulatory molecules to prime and activate tumour‐specific CD8⁺CTLs. Immunosuppressive tolerogenic DCs with reduced co‐stimulatory molecules may be a cause of impaired CTL induction. Hepa1‐6‐1 cells were established from the mouse hepatoma cell line Hepa1‐6; these cells grow continuously after subcutaneous implantation into syngeneic C57BL/6 (B6) mice and do not prime CD8⁺CTLs. In this study, we show that the growth of ongoing tumours was suppressed by activated CD8⁺CTLs with tumour‐specific cytotoxicity through the administration of the glycolipid α‐galactosylceramide (α‐GalCer), which is a compound known to stimulate invariant natural killer T (iNKT) cells and selectively activate DEC‐205⁺DCs. Moreover, we demonstrated that sequential repetitive intraperitoneal inoculation with α‐GalCer every 48 hr appeared to convert tolerogenic DEC‐205⁺DCs into immunogenic DCs with a higher expression of co‐stimulatory molecules and a stronger cross‐presentation capacity, which primed CTL precursors and induced tumour‐specific CD8⁺CTLs within the tumour environment without activating iNKT cells. These findings provide a new basis for cancer immunotherapy to convert tolerogenic DEC‐205⁺DCs within tumours into immunogenic DCs through the sequential administration of an immuno‐potent lipid/glycolipid, and then activated immunogenic DCs with sufficient expression of co‐stimulatory molecules prime and activate tumour‐specific CD8⁺CTLs within the tumour to control tumour growth.

Innate immunity and chronic rhinosinusitis: What we have learned from animal models

OBJECTIVE

Chronic rhinosinusitis (CRS) is a heterogeneous and multifactorial disease characterized by dysregulated inflammation. Abnormalities in innate immune function including sinonasal epithelial cell barrier function, mucociliary clearance, response to pathogen-associated molecular patterns (PAMPs) via pattern recognition receptors (PRRs), and the contribution of innate immune cells will be highlighted in this review.

DATA SOURCES

PubMed literature review.

REVIEW METHODS

A review of the literature was conducted to determine what we have learned from animal models in relation to innate immunity and chronic rhinosinusitis.

RESULTS

Dysregulation of innate immune mechanisms including sinonasal barrier function, mucociliary clearance, PAMPs, and innate immune cells such as eosinophils, mast cells, and innate lymphoid cells may contribute to CRS pathogenesis. Sinonasal inflammation has been studied using mouse, rat, rabbit, pig, and sheep explant or in vivo models. Study using these models has allowed for analysis of experimental therapeutics and furthered our understanding of the aforementioned aspects of the innate immune mechanism as it relates to sinonasal inflammation. These include augmenting mucociliary clearance through activation of the cystic fibrosis transmembrane conductance regulator (CFTR) and study of drug toxicity on ciliary beat frequency. Knockout models of Toll-like receptors (TLR) have demonstrated the critical role these PRRs play in allergic inflammation as loss of TLR2 and TLR4 leads to decreased lower airway inflammation. Mast cell deficient mice are less susceptible to ovalbumin-induced sinonasal inflammation.

CONCLUSION

Animal models have shed light as to the potential contribution of dysregulated innate immunity in chronic sinonasal inflammation.