Negative role of inducible PD-1 on survival of activated dendritic cells

PD-1 is a well-established negative regulator of T cell responses by inhibiting proliferation and cytokine production of T cells via interaction with its ligands, B7-H1 (PD-L1) and B7-DC (PD-L2), expressed on non-T cells. Recently, PD-1 was found to be expressed in innate cells, including activated DCs, and plays roles in suppressing production of inflammatory cytokines. In this study, we demonstrate that PD-1 KO DCs exhibited prolonged longevity compared with WT DCs in the dLNs after transfer of DCs into hind footpads. Interestingly, upon LPS stimulation, WT DCs increased the expression of PD-1 and started to undergo apoptosis. DCs, in spleen of LPS-injected PD-1 KO mice, were more resistant to LPS-mediated apoptosis in vivo than WT controls. Moreover, treatment of blocking anti-PD-1 mAb during DC maturation resulted in enhanced DC survival, suggesting that PD-1: PD-L interactions are involved in DC apoptosis. As a result, PD-1-deficient DCs augmented T cell responses in terms of antigen-specific IFN- production and proliferation of CD4 and CD8 T cells to a greater degree than WT DCs. Moreover, PD-1 KO DCs exhibited increased MAPK1 and CD40–CD40L signaling, suggesting a possible mechanism for enhanced DC survival in the absence of PD-1 expression. Taken together, our findings further extend the function of PD-1, which plays an important role in apoptosis of activated DCs and provides important implications for PD-1-mediated immune regulation. J. Leukoc. Biol. 95: 621–629; 2014.111101sciescopu

Parasitic Nematode-Induced CD4+Foxp3+T Cells Can Ameliorate Allergic Airway Inflammation

Background: The recruitment of CD4+CD25+Foxp3+T (Treg) cells is one of the most important mechanisms by which parasites down-regulate the immune system. Methodology/Principal Findings: We compared the effects of Treg cells from Trichinella spiralis-infected mice and uninfected mice on experimental allergic airway inflammation in order to understand the functions of parasite-induced Treg cells. After four weeks of T. spiralis infection, we isolated Foxp3-GFP-expressing cells from transgenic mice using a cell sorter. We injected CD4+Foxp3+ cells from T. spiralis-infected [Inf(+)Foxp3+] or uninfected [Inf(-)Foxp3+] mice into the tail veins of C57BL/6 mice before the induction of inflammation or during inflammation. Inflammation was induced by ovalbumin (OVA)-alum sensitization and OVA challenge. The concentrations of the Th2-related cytokines IL-4, IL-5, and IL-13 in the bronchial alveolar lavage fluid and the levels of OVA-specific IgE and IgG1 in the serum were lower in mice that received intravenous application of Inf(+)Foxp3+ cells [IV(inf):+(+) group] than in control mice. Some features of allergic airway inflammation were ameliorated by the intravenous application of Inf(-)Foxp3+ cells [IV(inf):+(-) group], but the effects were less distinct than those observed in the IV(inf):+(+) group. We found that Inf(+)Foxp3+ cells migrated to inflammation sites in the lung and expressed higher levels of Treg-cell homing receptors (CCR5 and CCR9) and activation markers (Klrg1, Capg, GARP, Gzmb, OX40) than did Inf(-)Foxp3+ cells. Conclusion/Significance: T. spiralis infection promotes the proliferation and functional activation of Treg cells. Parasiteinduced Treg cells migrate to the inflammation site and suppress immune responses more effectively than non-parasiteinduced Treg cells. The adoptive transfer of Inf(+)Foxp3+ cells is an effective method for the treatment and prevention of allergic airway diseases in mice and is a promising therapeutic approach for the treatment of allergic airway diseases. (c) 2014 Kang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.1891sciescopu

Combined two-photon microscopy and optical coherence tomography using individually optimized sources

The combination of two-photon microscopy (TPM) and optical coherence tomography (OCT) is useful in conducting in-vivo tissue studies, because they provide complementary information regarding tissues. In the present study, we developed a new combined system using separate light sources and scanners for individually optimal imaging conditions. TPM used a Ti-Sapphire laser and provided molecular and cellular information in microscopic tissue regions. Meanwhile, OCT used a wavelength-swept source centered at 1300 nm and provided structural information in larger tissue regions than TPM. The system was designed to do simultaneous imaging by combining light from both sources. TPM and OCT had the field of view values of 300 mu m and 800 mu m on one side respectively with a 20x objective. TPM had resolutions of 0.47 mu m and 2.5 mu m in the lateral and axial directions respectively, and an imaging speed of 40 frames/s. OCT had resolutions of 5 mu m and 8 mu m in lateral and axial directions respectively, a sensitivity of 97dB, and an imaging speed of 0.8 volumes per second. This combined system was tested with simple microsphere specimens, and was then applied to image small intestine and ear tissues of mouse models ex-vivo. Molecular, cellular, and structural information of the tissues were visualized using the proposed combined system. (C) 2011 Optical Society of AmericaX1122sciescopu

Protein energy malnutrition alters mucosal IgA responses and reduces mucosal vaccine efficacy in mice

Oral vaccine responsiveness is often lower in children from less developed countries. Childhood malnutrition may be associated with poor immune response to oral vaccines. The present study was designed to investigate whether protein energy malnutrition (PEM) impairs B cell immunity and ultimately reduces oral vaccine efficacy in a mouse model. Purified isocaloric diets containing low protein (1/10 the protein of the control diet) were used to determine the effect of PEM. PEM increased both nonspecific total IgA and oral antigen-specific IgA in serum without alteration of gut permeability. However, PEM decreased oral antigen-specific IgA in feces, which is consistent with decreased expression of polymeric Immunoglobulin receptor (pIgR) in the small intestine. Of note, polymeric IgA was predominant in serum under PEM. In addition, PEM altered B cell development status in the bone marrow and increased the frequency of IgA-secreting B cells, as well as IgA secretion by long-lived plasma cells in the small intestinal lamina propria. Moreover, PEM reduced the protective efficacy of the mucosally administered cholera vaccine and recombinant attenuated Salmonella enterica serovar Typhimurium vaccine in a mouse model. Our results suggest that PEM can impair mucosal immunity where IgA plays an important role in host protection and may partly explain the reduced efficacy of oral vaccines in malnourished subjects. © 2017 European Federation of Immunological Societie1221sciescopu

Delivery of IL-12p40 ameliorates DSS-induced colitis by suppressing IL-17A expression and inflammation in the intestinal mucosa

IL-12p40 homodimer is a natural antagonist of IL-12 and IL-23, which are potent pro-inflammatory cytokines required for Th1 and Th17 immune responses, respectively. It has been reported that Th17 response is involved in inflammatory bowel disease (IBD), a chronic disorder of the digestive system with steadily increasing incidence. Here, we investigated the effects of IL-12p40 delivered via recombinant adenovirus (rAd/IL-12p40) or mesenchymal stem cells (MSC/IL-12p40) in a dextran sulfate sodium salt (DSS)-induced colitis model. Injection of rAd/IL-12p40 or MSC/IL-12p40 efficiently attenuated colitis symptoms and tissue damage, Leading to an increased survival rate. Moreover, IL-12p40 delivery suppressed IL-17A, but enhanced IFN-gamma production from mesenteric lymph node cells, supporting the preferential suppression of IL-23 by IL-12p40 homodimer in vitro and the suppression of Th17 responses in vivo. Our results demonstrate that IL-12p40 delivery ameliorates DSS-induced colitis by suppressing IL-17A production and inflammation in the intestinal mucosa, providing an effective new therapeutic strategy for IBDs. (c) 2012 Elsevier Inc. All rights reserved.X112019sciescopu

Protective effects of Fc-fused PD-L1 on two different animal models of colitis

Objective Programmed death-ligand 1 (PD-L1) has been shown to negatively regulate immune responses via its interaction with PD-1 receptor. In this study, we investigated the effects of PD-L1-Fc treatment on intestinal inflammation using two murine models of inflammatory colitis induced by dextran sulfate sodium (DSS) and T-cell transfer. Design The anti-colitis effect of adenovirus expressing Fc-conjugated PD-L1 (Ad/PD-L1-Fc) and recombinant PD-L1-Fc protein was evaluated in DSS-treated wild-type and Rag-1 knockout (KO) mice. We examined differentiation of T-helper cells, frequency of innate immune cells, and cytokine production by dendritic cells (DCs) in the colon from DSS-treated mice after PD-L1-Fc administration. In Rag-1 KO mice reconstituted with CD4 CD45RBhigh T cells, we assessed the treatment effect of PD-L1-Fc protein on the development of colitis. Results Administration of Ad/PD-L1-Fc significantly ameliorated DSS-induced colitis, which was accompanied by diminished frequency of interleukin (IL)-17Aproducing CD4 T cells and increased interferon-γ- producing CD4 T cells in the colon of DSS-fed mice. The anti-colitic effect of PD-L1-Fc treatment was also observed in DSS-treated Rag-1 KO mice, indicating lymphoid cell independency. PD-L1-Fc modulated cytokine production by colonic DCs and the effect was dependent on PD-1 expression. Furthermore, PD-L1-Fc protein could significantly reduce the severity of colitis in CD4 CD45RBhigh T-cell-transferred Rag-1 KO mice. Conclusions Based on the protective effect of PD-L1- Fc against DSS-induced and T-cell-induced colitis, our results suggest that PD-1-mediated inhibitory signals have a crucial role in limiting the development of colonic inflammation. This implicates that PD-L1-Fc may provide a novel therapeutic approach to treat inflammatory bowel disease.115141sciescopu

Two-photon microscopy of Paneth cells in the small intestine of live mice

Abstract Paneth cells are one of the principal epithelial cell types in the small intestine, located at the base of intestinal crypts. Paneth cells play key roles in intestinal host-microbe homeostasis via granule secretion, and their dysfunction is implicated in pathogenesis of several diseases including Crohn’s disease. Despite their physiological importance, study of Paneth cells has been hampered by the limited accessibility and lack of labeling methods. In this study, we developed a simple in vivo imaging method of Paneth cells in the intact mouse small intestine by using moxifloxacin and two-photon microscopy (TPM). Moxifloxacin, an FDA-approved antibiotic, was used for labeling cells and its fluorescence was strongly observed in Paneth cell granules by TPM. Moxifloxacin labeling of Paneth cell granules was confirmed by molecular counterstaining. Comparison of Paneth cells in wild type, genetically obese (ob/ob), and germ-free (GF) mice showed different granule distribution. Furthermore, Paneth cell degranulation was observed in vivo. Our study suggests that TPM with moxifloxacin labeling can serve as a useful tool for studying Paneth cell biology and related diseases

Parasitic Nematode-Induced CD4⁺Foxp3⁺T Cells Can Ameliorate Allergic Airway Inflammation

<div><p>Background</p><p>The recruitment of CD4⁺CD25⁺Foxp3⁺T (T_reg) cells is one of the most important mechanisms by which parasites down-regulate the immune system.</p><p>Methodology/Principal Findings</p><p>We compared the effects of T_reg cells from <i>Trichinella spiralis</i>-infected mice and uninfected mice on experimental allergic airway inflammation in order to understand the functions of parasite-induced T_reg cells. After four weeks of <i>T. spiralis</i> infection, we isolated Foxp3-GFP-expressing cells from transgenic mice using a cell sorter. We injected CD4⁺Foxp3⁺ cells from <i>T. spiralis</i>-infected [Inf(+)Foxp3⁺] or uninfected [Inf(-)Foxp3⁺] mice into the tail veins of C57BL/6 mice before the induction of inflammation or during inflammation. Inflammation was induced by ovalbumin (OVA)-alum sensitization and OVA challenge. The concentrations of the Th2-related cytokines IL-4, IL-5, and IL-13 in the bronchial alveolar lavage fluid and the levels of OVA-specific IgE and IgG1 in the serum were lower in mice that received intravenous application of Inf(+)Foxp3⁺ cells [IV(inf):+(+) group] than in control mice. Some features of allergic airway inflammation were ameliorated by the intravenous application of Inf(-)Foxp3⁺ cells [IV(inf):+(-) group], but the effects were less distinct than those observed in the IV(inf):+(+) group. We found that Inf(+)Foxp3⁺ cells migrated to inflammation sites in the lung and expressed higher levels of T_reg-cell homing receptors (CCR5 and CCR9) and activation markers (Klrg1, Capg, GARP, Gzmb, OX40) than did Inf(-)Foxp3⁺ cells.</p><p>Conclusion/Significance</p><p><i>T. spiralis</i> infection promotes the proliferation and functional activation of T_reg cells. Parasite-induced T_reg cells migrate to the inflammation site and suppress immune responses more effectively than non-parasite-induced T_reg cells. The adoptive transfer of Inf(+)Foxp3⁺ cells is an effective method for the treatment and prevention of allergic airway diseases in mice and is a promising therapeutic approach for the treatment of allergic airway diseases.</p></div