Search

Intestinal inflammation can be accompanied by osteoporosis, but their relationship, mediated by immune responses, remains unclear. Here, we investigated a non-IgE-mediated food-allergic enteropathy model of ovalbumin (OVA) 23-3 mice expressing OVA-specific T-cell-receptor transgenes. Mesenteric lymph nodes (MLNs) and their pathogenic CD4+T cells were important to enteropathy occurrence and exacerbation when the mice were fed an egg-white (EW) diet. EW-fed OVA23-3 mice also developed bone loss and increased CD44hiCD62LloCD4+T cells in the MLNs and bone marrow (BM); these changes were attenuated by MLN, but not spleen, resection. We fed an EW diet to F1 cross offspring from OVA23-3 mice and a mouse line expressing the photoconvertible protein KikGR to track MLN CD4+T cells. Photoconverted MLN CD44hiCD62LloCD4+T cells migrated predominantly to the BM; pit formation assay proved their ability to promote bone damage via osteoclasts. Significantly greater expression of IL-4 mRNA in MLN CD44hiCD62LloCD4+T cells and bone was observed in EW-fed OVA23-3 mice. Anti-IL-4 monoclonal antibody injection canceled bone loss in the primary inflammation phase in EW-fed mice, but less so in the chronic phase. This novel report shows the specific inflammatory relationship, via Th2-dominant-OVA-specific T cells and IL-4 production, between MLNs and bone, a distant organ, in food-allergic enteropathy.

Intestinal inflammation can be accompanied by osteoporosis, but their relationship, mediated by immune responses, remains unclear. Here, we investigated a non-IgE-mediated food-allergic enteropathy model of ovalbumin (OVA) 23-3 mice expressing OVA-specific T-cell-receptor transgenes. Mesenteric lymph nodes (MLNs) and their pathogenic CD4+T cells were important to enteropathy occurrence and exacerbation when the mice were fed an egg-white (EW) diet. EW-fed OVA23-3 mice also developed bone loss and increased CD44hiCD62LloCD4+T cells in the MLNs and bone marrow (BM); these changes were attenuated by MLN, but not spleen, resection. We fed an EW diet to F1 cross offspring from OVA23-3 mice and a mouse line expressing the photoconvertible protein KikGR to track MLN CD4+T cells. Photoconverted MLN CD44hiCD62LloCD4+T cells migrated predominantly to the BM; pit formation assay proved their ability to promote bone damage via osteoclasts. Significantly greater expression of IL-4 mRNA in MLN CD44hiCD62LloCD4+T cells and bone was observed in EW-fed OVA23-3 mice. Anti-IL-4 monoclonal antibody injection canceled bone loss in the primary inflammation phase in EW-fed mice, but less so in the chronic phase. This novel report shows the specific inflammatory relationship, via Th2-dominant-OVA-specific T cells and IL-4 production, between MLNs and bone, a distant organ, in food-allergic enteropathy.

Obesity is a worldwide epidemic that predisposes individuals to many age-associated diseases, but its exact effects on organ dysfunction are largely unknown1. Hair follicles—mini-epithelial organs that grow hair—are miniaturized by ageing to cause hair loss through the depletion of hair follicle stem cells (HFSCs)2. Here we report that obesity-induced stress, such as that induced by a high-fat diet (HFD), targets HFSCs to accelerate hair thinning. Chronological gene expression analysis revealed that HFD feeding for four consecutive days in young mice directed activated HFSCs towards epidermal keratinization by generating excess reactive oxygen species, but did not reduce the pool of HFSCs. Integrative analysis using stem cell fate tracing, epigenetics and reverse genetics showed that further feeding with an HFD subsequently induced lipid droplets and NF-κB activation within HFSCs via autocrine and/or paracrine IL-1R signalling. These integrated factors converge on the marked inhibition of Sonic hedgehog (SHH) signal transduction in HFSCs, thereby further depleting lipid-laden HFSCs through their aberrant differentiation and inducing hair follicle miniaturization and eventual hair loss. Conversely, transgenic or pharmacological activation of SHH rescued HFD-induced hair loss. These data collectively demonstrate that stem cell inflammatory signals induced by obesity robustly represses organ regeneration signals to accelerate the miniaturization of mini-organs, and suggests the importance of daily prevention of organ dysfunction.

Pancreatic islet inflammation plays a crucial role in the etiology of type 2 diabetes (T2D). Macrophages residing in pancreatic islets have emerged as key players in islet inflammation. Macrophages express a plethora of innate immune receptors that bind to environmental and metabolic cues and integrate these signals to trigger an inflammatory response that contributes to the development of islet inflammation. One such receptor, Dectin-2, has been identified within pancreatic islets; however, its role in glucose metabolism remains largely unknown. Here we have demonstrated that mice lacking Dectin-2 exhibit local inflammation within islets, along with impaired insulin secretion and β-cell dysfunction. Our findings indicate that these effects are mediated by proinflammatory cytokines, such as interleukin (IL)-1α and IL-6, which are secreted by macrophages that have acquired an inflammatory phenotype because of the loss of Dectin-2. This study provides novel insights into the mechanisms underlying the role of Dectin-2 in the development of islet inflammation.

Myeloid C‐type lectin receptors (CLRs), which consist of an extracellular carbohydrate recognition domain and intracellular signal transducing motif such as the immunoreceptor tyrosine‐based activation motif (ITAM) or immunoreceptor tyrosine‐based inhibitory motif (ITIM), are innate immune receptors primarily expressed on myeloid lineage cells such as dendritic cells (DCs) and Mϕs. CLRs play important roles in host defense against infection by fungi and bacteria by recognizing specific carbohydrate components of these pathogens. However, these immune receptors also make important contributions to immune homeostasis of mucosa and skin in mammals by recognizing components of microbiota, as well as by recognizing self‐components such as alarmins from dead cells and noncanonical non‐carbohydrate ligands. CLR deficiency not only induces hypersensitivity to infection, but also causes dysregulation of muco‐cutaneous immune homeostasis, resulting in the development of allergy, inflammation, autoimmunity, and tumors. In this review, we introduce recent discoveries regarding the roles of myeloid CLRs in the immune system exposed to the environment, and discuss the roles of these lectin receptors in the development of colitis, asthma, psoriasis, atopic dermatitis, and cancer. Although some CLRs are suggested to be involved in the development of these diseases, the function of CLRs and their ligands still largely remain to be elucidated. Review of the roles of myeloid C‐type lectin receptors, which regulate immune responses in muco‐epithelium, skin, and tumors, in modulating the development of colitis, asthma, psoriasis, atopic dermatitis, and cancer.

The C-type lectin receptor–Syk (spleen tyrosine kinase) adaptor CARD9 facilitates protective antifungal immunity within the central nervous system (CNS), as human deficiency in CARD9 causes susceptibility to fungus-specific, CNS-targeted infection. CARD9 promotes the recruitment of neutrophils to the fungus-infected CNS, which mediates fungal clearance. In the present study we investigated host and pathogen factors that promote protective neutrophil recruitment during invasion of the CNS by Candida albicans. The cytokine IL-1β served an essential function in CNS antifungal immunity by driving production of the chemokine CXCL1, which recruited neutrophils expressing the chemokine receptor CXCR2. Neutrophil-recruiting production of IL-1β and CXCL1 was induced in microglia by the fungus-secreted toxin Candidalysin, in a manner dependent on the kinase p38 and the transcription factor c-Fos. Notably, microglia relied on CARD9 for production of IL-1β, via both transcriptional regulation of Il1band inflammasome activation, and of CXCL1 in the fungus-infected CNS. Microglia-specific Card9deletion impaired the production of IL-1β and CXCL1 and neutrophil recruitment, and increased fungal proliferation in the CNS. Thus, an intricate network of host–pathogen interactions promotes antifungal immunity in the CNS; this is impaired in human deficiency in CARD9, which leads to fungal disease of the CNS. Innate immunity protects the central nervous system against fungal pathogens. Lionakis and colleagues identify Candidalysin, a Candidavirulence factor that elicits microglial expression of the cytokine IL-1β and chemokine CXCL1 and facilitates neutrophil recruitment. Alteration of this pathway impairs antifungal responses.

Dendritic cell-associated C-type lectin-2 (i.e., dectin-2) recognizes fungal polysaccharides, including α-mannan. Dectin-2–mediated recognition of fungi, such as Candida albicans, leads to NF-κB activation, which induces production of inflammatory cytokines. However, the role of dectin-2 in skin wound healing remains unclear. In this study, we sought to determine how dectin-2 deficiency and the administration of α-mannan affected the wound healing process. Full-thickness wounds were created on the backs of wild type C57BL/6 and dectin-2–deficient mice. We analyzed wound closure, histological findings, and re-epithelialization. We also examined the neutrophilic inflammatory responses and neutrophil extracellular trap (NET)-osis at the wound sites after administration of α-mannan. The percent wound closure and re-epithelialization was significantly accelerated in dectin-2–knockout mice compared with wild-type mice on days 3 and 5 after wounding. In contrast, administration of α-mannan delayed wound closure in wild-type mice, and these responses were canceled in dectin-2–knockout mice. Furthermore, mice administered α-mannan, neutrophil infiltration was prolonged, and the expression of citrullinated histone, an indicator of NETosis, at the wound sites was accelerated. Administration of a neutrophil elastase inhibitor significantly improved the delayed wound healing caused by α-mannan. These results suggest that dectin-2 may have a deep impact on the skin wound healing process through regulation of neutrophilic responses.

Tissue-resident memory T cells (TRMs) are a novel nonvascular memory T cell subset. Although CD8+TRMs are well-characterized, CD4+TRMs—especially lung-resident memory Th17 cells—are still being defined. In this study, we characterized lung-resident memory Th17 cells (lung TRM17) and their role in protection against the highly virulent fungus Cryptococcus gattii. We found that intravenously transferred DCs preferentially migrated to lungs and attracted recipient DCs and led to the induction of long-lived Th17 cells expressing characteristic markers. This population could be clearly discriminated from circulating T cells by intravascular staining and was not depleted by the immunosuppressive agent FTY720. The C. gattiiantigen re-stimulation assay revealed that vaccine-induced lung Th17 cells produced IL-17A but not IFNγ. The DC vaccine significantly increased IL-17A production and suppressed fungal burden in the lungs and improved the survival of mice infected with C. gattii. This protective effect was significantly reduced in the IL-17A knockout (KO) mice, but not in the FTY720-treated mice. The protective effect also coincided with the activation of neutrophils and multinucleated giant cells, and these inflammatory responses were suppressed in the vaccinated IL-17A KO mice. Overall, these data demonstrated that the systemic DC vaccine induced lung TRM17, which played a substantial role in anti-fungal immunity.

Tissue-resident memory T cells (TRMs) are a novel nonvascular memory T cell subset. Although CD8+TRMs are well-characterized, CD4+TRMs—especially lung-resident memory Th17 cells—are still being defined. In this study, we characterized lung-resident memory Th17 cells (lung TRM17) and their role in protection against the highly virulent fungus Cryptococcus gattii. We found that intravenously transferred DCs preferentially migrated to lungs and attracted recipient DCs and led to the induction of long-lived Th17 cells expressing characteristic markers. This population could be clearly discriminated from circulating T cells by intravascular staining and was not depleted by the immunosuppressive agent FTY720. The C. gattiiantigen re-stimulation assay revealed that vaccine-induced lung Th17 cells produced IL-17A but not IFNγ. The DC vaccine significantly increased IL-17A production and suppressed fungal burden in the lungs and improved the survival of mice infected with C. gattii. This protective effect was significantly reduced in the IL-17A knockout (KO) mice, but not in the FTY720-treated mice. The protective effect also coincided with the activation of neutrophils and multinucleated giant cells, and these inflammatory responses were suppressed in the vaccinated IL-17A KO mice. Overall, these data demonstrated that the systemic DC vaccine induced lung TRM17, which played a substantial role in anti-fungal immunity.

Homeostasis in the ileum, which is commonly disrupted in patients with Crohn’s disease, involves ongoing immune responses. To study how homeostatic processes of the ileum impact CD4+T cell responses, we used TCR transgenic tools to breed mice that spontaneously produced CD4+T cells reactive to an antigen expressed in the ileum. At an early age, the ilea of these mice exhibit crypt hyperplasia and accumulate increased numbers of TH17 cells bearing non-transgenic clonotypes. Half of these mice subsequently developed colitis linked to broad mucosal infiltration by TH17 and TH1 cells expressing non-transgenic clonotypes, chronic wasting disease and loss of ileal crypt hyperplasia. By contrast, adult mice with normal growth continued to exhibit TH17-associated ileal crypt hyperplasia and additionally accumulated ileal-reactive Treg cells. Both IL-17A and IFNγ were protective, as their deficiency precluded ileal-reactive Treg accumulation and exacerbated colitic disease. IL-23R blockade prevented progression to colitis, whereas nTreg cell transfers prevented colitic disease, ileal crypt hyperplasia and ileal-reactive Treg accumulation. Thus, our studies identify an IL-17A and IFNγ-dependent homeostatic process that mobilizes ileal-reactive Treg cells and is disrupted by IL-23.

The cytokines IL-17A and IL-17F have 50% amino-acid identity and bind the same receptor; however, their functional differences have remained obscure. Here we found that Il17f–/–mice resisted chemically induced colitis, but Il17a–/–mice did not, and that Il17f−/−CD45RBhiCD4+T cells induced milder colitis in lymphocyte-deficient Rag2–/–mice, accompanied by an increase in intestinal regulatory T cells (Tregcells). Clostridiumcluster XIVa in colonic microbiota capable of inducing Tregcells was increased in both Il17f−/−mice and mice given transfer Il17f−/−T cells, due to decreased expression of a group of antimicrobial proteins. There was substantial production of IL-17F, but not of IL-17A, not only by naive T cells but also by various colon-resident cells under physiological conditions. Furthermore, antibody to IL-17F suppressed the development of colitis, but antibody to IL-17A did not. These observations suggest that IL-17F is an effective target for the treatment of colitis. The cytokines IL-17A and IL-17F bind via same receptor. Iwakura and colleagues demonstrate different functions for IL-17A and IL-17F in the gut, with the latter altering the production of antimicrobial peptides with consequent effects on the microbiota, the induction of Tregcells and immune-system homeostasis.

Homeostasis in the ileum, which is commonly disrupted in patients with Crohn's disease, involves ongoing immune responses. To study how homeostatic processes of the ileum impact CD4+T cell responses, we used TCR transgenic tools to breed mice that spontaneously produced CD4+T cells reactive to an antigen expressed in the ileum. At an early age, the ilea of these mice exhibit crypt hyperplasia and accumulate increased numbers of TH17 cells bearing non-transgenic clonotypes. Half of these mice subsequently developed colitis linked to broad mucosal infiltration by TH17 and TH1 cells expressing non-transgenic clonotypes, chronic wasting disease and loss of ileal crypt hyperplasia. By contrast, adult mice with normal growth continued to exhibit TH17-associated ileal crypt hyperplasia and additionally accumulated ileal-reactive Treg cells. Both IL-17A and IFNγ were protective, as their deficiency precluded ileal-reactive Treg accumulation and exacerbated colitic disease. IL-23R blockade prevented progression to colitis, whereas nTreg cell transfers prevented colitic disease, ileal crypt hyperplasia and ileal-reactive Treg accumulation. Thus, our studies identify an IL-17A and IFNγ-dependent homeostatic process that mobilizes ileal-reactive Treg cells and is disrupted by IL-23.

Nonalcoholic fatty liver disease (NAFLD), a common prelude to cirrhosis and hepatocellular carcinoma, is the most common chronic liver disease worldwide. Defining the molecular mechanisms underlying the pathogenesis of NAFLD has been hampered by a lack of animal models that closely recapitulate the severe end of the disease spectrum in humans, including bridging hepatic fibrosis. Here we demonstrate that a novel experimental model employing thermoneutral housing, as opposed to standard housing, resulted in lower stress-driven production of corticosterone, augmented mouse proinflammatory immune responses and markedly exacerbated high-fat diet (HFD)-induced NAFLD pathogenesis. Disease exacerbation at thermoneutrality was conserved across multiple mouse strains and was associated with augmented intestinal permeability, an altered microbiome and activation of inflammatory pathways that are associated with the disease in humans. Depletion of Gram-negative microbiota, hematopoietic cell deletion of Toll-like receptor 4 (TLR4) and inactivation of the IL-17 axis resulted in altered immune responsiveness and protection from thermoneutral-housing-driven NAFLD amplification. Finally, female mice, typically resistant to HFD-induced obesity and NAFLD, develop full disease characteristics at thermoneutrality. Thus, thermoneutral housing provides a sex-independent model of exacerbated NAFLD in mice and represents a novel approach for interrogation of the cellular and molecular mechanisms underlying disease pathogenesis.

Candida albicanscan enter skeletal tissue through a skin wound in an immunocompromised host or by contamination during orthopedic surgery. Such Candidaosteomyelitis is accompanied by severe pain and bone destruction. It is established that nociceptor innervation occurs in skin and bone, but the mechanisms of nociceptive modulation in fungal inflammation remain unclear. In this study, we show that C. albicansstimulates Nav1.8-positive nociceptors via the β-glucan receptor Dectin-1 to induce calcitonin gene-related peptide (CGRP). This induction of CGRP is independent of Bcl-10 or Malt-1 but dependent on transient receptor potential cation channel subfamily V member 1 (TRPV1)/transient receptor potential cation channel subfamily A member 1 (TRPA1) ion channels. Hindpaw β-glucan injection after Nav1.8-positive nociceptor ablation or in TRPV1/TRPA1 deficiency showed dramatically increased osteoinflammation accompanied by impaired CGRP production. Strikingly, CGRP suppressed β-glucan-induced inflammation and osteoclast multinucleation via direct suppression of nuclear factor-κB (NF-κB) p65 by the transcriptional repressor Jdp2 and inhibition of actin polymerization, respectively. These findings clearly suggest a role for Dectin-1-mediated sensocrine pathways in the resolution of fungal osteoinflammation.

Keratinocytes undergo a unique type of programmed cell death known as cornification, which leads to the formation of the stratum corneum (SC), the main physical barrier of the epidermis. A defective epidermal barrier is a hallmark of the two most common inflammatory skin disorders, psoriasis, and atopic dermatitis. However, the detailed molecular mechanisms of skin barrier formation are not yet fully understood. Here, we showed that downregulation of phospholipase C (PLC) δ1, a Ca2+-mobilizing and phosphoinositide-metabolizing enzyme abundantly expressed in the epidermis, impairs the barrier functions of the SC. PLCδ1 downregulation also impairs localization of tight junction proteins. Loss of PLCδ1 leads to a decrease in intracellular Ca2+concentrations and nuclear factor of activated T cells activity, along with hyperactivation of p38 mitogen-activated protein kinase (MAPK) and inactivation of RhoA. Treatment with a p38 MAPK inhibitor reverses the barrier defects caused by PLCδ1 downregulation. Interestingly, this treatment also attenuates psoriasis-like skin inflammation in imiquimod-treated mice. These findings demonstrate that PLCδ1 is essential for epidermal barrier integrity. This study also suggests a possible link between PLCδ1 downregulation, p38 MAPK hyperactivation, and barrier defects in psoriasis-like skin inflammation.

Hematopoietic stem cell (HSC) transplantation (HSCT) for malignancy requires toxic pre‐conditioning to maximize anti‐tumor effects and donor‐HSC engraftment. While this induces bone marrow (BM)‐localized inflammation, how this BM environmental change affects transplanted HSCs in vivo remains largely unknown. We here report that, depending on interval between irradiation and HSCT, residence within lethally irradiated recipient BM compromises donor‐HSC reconstitution ability. Both in vivo and in vitro we demonstrate that, among inflammatory cytokines, TNF‐α plays a role in HSC damage: TNF‐α stimulation leads to accumulation of reactive oxygen species (ROS) in highly purified hematopoietic stem/progenitor cells (HSCs/HSPCs). Transplantation of flow‐cytometry—sorted murine HSCs reveals damaging effects of accumulated ROS on HSCs. Short‐term incubation either with an specific inhibitor of tumor necrosis factor receptor 1 signaling or an antioxidant N‐acetyl‐L‐cysteine (NAC) prevents TNF‐α‐mediated ROS accumulation in HSCs. Importantly, pre‐transplantation exposure to NAC successfully demonstrats protective effects in inflammatory BM on graft‐HSCs, exhibiting better reconstitution capability than that of nonprotected control grafts. We thus suggest that in vivo protection of graft‐HSCs from BM inflammation is a feasible and attractive approach, which may lead to improved hematopoietic reconstitution kinetics in transplantation with myeloablative conditioning that inevitably causes inflammation in recipient BM. StemCells2017;35:989–1002 Schematic illustration of the “HSC protection in transplantation” concept that we proposed in this study. Following harsh pre‐conditioning, a certain level of inflammation occurs within the bone marrow environment. At the site of injury, the presence of TNF‐α will lead to an accumulation of reactive oxygen species within graft‐hematopoietic stem cells (HSCs) resulting in perturbed hematopoiesis. Prevention of these negative outcomes may be achieved by pre‐incubating HSCs with N‐acetylcysteine. In this scenario, graft‐HSCs are considered to be “protected” within an inflammation‐prone microenvironment thus improving hematopoiesis.

Innate γδ T cells expressing Vγ6 produce IL-17A at an early stage following infection with Mycobacterium bovis Bacillus Calmette-Guérin (BCG). In this study, we used IL-21 receptor knockout (IL-21R KO) mice and IL-21-producing recombinant BCG mice (rBCG-Ag85B-IL-21) to examine the role of IL-21 in the regulation of IL-17A-producing innate γδ T-cell response following BCG infection. IL-17A-producing Vγ6+γδ T cells increased in the peritoneal cavity of IL-21R KO mice more than in wild type mice after BCG infection. In contrast, the number of IL-17A-producing Vγ6+γδ T cells was significantly lower after inoculation with rBCG-Ag85B-IL-21 compared with control rBCG-Ag85B. Notably, exogenous IL-21 selectively induced apoptosis of IL-17A-producing Vγ6+γδ T cells via Bim. Thus, these results suggest that IL-21 acts as a potent inhibitor of a IL-17A-producing γδ T-cell subset during BCG infection.

Dermatophytoses are chronic fungal infections, the main causative agent of which is Trichophyton rubrum(T. rubrum). Despite their high occurrence worldwide, the immunological mechanisms underlying these diseases remain largely unknown. Here, we uncovered the C-type lectin receptors, Dectin-1 and Dectin-2, as key elements in the immune response to T. rubruminfection in a model of deep dermatophytosis. In vitro, we observed that deficiency in Dectin-1 and Dectin-2 severely compromised cytokine production by dendritic cells. In vivo, mice lacking Dectin-1 and/or Dectin-2 showed an inadequate pro-inflammatory cytokine production in response to T. rubruminfection, impairing its resolution. Strikingly, neither adaptive immunity nor IL-17 response were required for fungal clearance, highlighting innate immunity as the main checkpoint in the pathogenesis of T. rubruminfection.

Interleukin 1β (IL-1β) is critical for the in vivo survival, expansion and effector function of IL-17–producing helper T (TH17) cells during autoimmune responses, including experimental autoimmune encephalomyelitis (EAE). However, the spatiotemporal role and cellular source of IL-1β during EAE pathogenesis are poorly defined. In the present study, we uncovered a T cell–intrinsic inflammasome that drives IL-1β production during TH17-mediated EAE pathogenesis. Activation of T cell antigen receptors induced expression of pro-IL-1β, whereas ATP stimulation triggered T cell production of IL-1β via ASC-NLRP3–dependent caspase-8 activation. IL-1R was detected on TH17 cells but not on type 1 helper T (TH1) cells, and ATP-treated TH17 cells showed enhanced survival compared with ATP-treated TH1 cells, suggesting autocrine action of TH17-derived IL-1β. Together these data reveal a critical role for IL-1β produced by a TH17 cell–intrinsic ASC–NLRP3–caspase-8 inflammasome during inflammation of the central nervous system.

Dendritic cell immunoreceptor (DCIR; Clec4a2), a member of the C-type lectin receptor family, plays important roles in homeostasis of the immune and bone systems. However, the intestinal role of this molecule is unclear. Here, we show that dextran sodium sulfate (DSS)-induced colitis and azoxymethane-DSS-induced intestinal tumors are reduced in Clec4a2−/−mice independently of intestinal microbiota. STAT5 phosphorylation and expression of Csf2and tight junction genes are enhanced, while Il17aand Cxcl2are suppressed in the Clec4a2−/−mouse colon, which exhibits reduced infiltration of neutrophils and myeloid-derived suppressor cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) administration ameliorates DSS colitis associated with reduced Il17aand enhanced tight junction gene expression, whereas anti-GM-CSF exacerbates symptoms. Furthermore, anti-NA2, a ligand for DCIR, ameliorates colitis and prevents colorectal tumors. These observations indicate that blocking DCIR signaling ameliorates colitis and suppresses colonic tumors, suggesting DCIR as a possible target for the treatment of these diseases.

Organ transplantation has seen an increased use of organs from older donors over the past decades in an attempt to meet the globally growing shortage of donor organs. However, inferior transplantation outcomes when older donor organs are used represent a growing challenge.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative therapy for various hematopoietic disorders. Graft-versus-host disease (GVHD) and infections are the major obstacles of HSCT, and their close relationship has been suggested. Although roles of bacterial and viral infections in the pathophysiology of GVHD are well described, impacts of fungal infection on GVHD remain to be elucidated. In mouse models of GVHD, injection of α-mannan (Mn), a major component of fungal cell wall, or heat-killed Candida albicans exacerbated GVHD, particularly in the lung. Mn-induced donor T-cell polarization toward Th17 and lung-specific chemokine environment in GVHD led to accumulation of Th17 cells in the lung. The detrimental effects of Mn on GVHD depended on donor IL-17A production and host C-type lectin receptor Dectin-2. These results suggest a previously unrecognized link between pulmonary GVHD and fungal infection after allogeneic HSCT.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative therapy for various hematopoietic disorders. Graft-versus-host disease (GVHD) and infections are the major obstacles of HSCT, and their close relationship has been suggested. Although roles of bacterial and viral infections in the pathophysiology of GVHD are well described, impacts of fungal infection on GVHD remain to be elucidated. In mouse models of GVHD, injection of α-mannan (Mn), a major component of fungal cell wall, or heat-killed Candida albicansexacerbated GVHD, particularly in the lung. Mn-induced donor T-cell polarization toward Th17 and lung-specific chemokine environment in GVHD led to accumulation of Th17 cells in the lung. The detrimental effects of Mn on GVHD depended on donor IL-17A production and host C-type lectin receptor Dectin-2. These results suggest a previously unrecognized link between pulmonary GVHD and fungal infection after allogeneic HSCT.

ABSTRACTDectin-2 is a C-type lectin receptor that recognizes high mannose polysaccharides. Cryptococcus neoformans, a yeast-form fungal pathogen, is rich in polysaccharides in its cell wall and capsule. In the present study, we analyzed the role of Dectin-2 in the host defense against C. neoformansinfection. In Dectin-2 gene-disrupted (knockout) (Dectin-2KO) mice, the clearance of this fungus and the inflammatory response, as shown by histological analysis and accumulation of leukocytes in infected lungs, were comparable to those in wild-type (WT) mice. The production of type 2 helper T (Th2) cytokines in lungs was higher in Dectin-2KO mice than in WT mice after infection, whereas there was no difference in the levels of production of Th1, Th17, and proinflammatory cytokines between these mice. Mucin production was significantly increased in Dectin-2KO mice, and this increase was reversed by administration of anti-interleukin 4 (IL-4) monoclonal antibody (MAb). The levels of expression of β1-defensin, cathelicidin, surfactant protein A (Sp-A), and Sp-D in infected lungs were comparable between these mice. In in vitroexperiments, IL-12p40 and tumor necrosis factor alpha (TNF-α) production and expression of CD86 and major histocompatibility complex (MHC) class II by bone marrow-derived dendritic cells and alveolar macrophages were completely abrogated in Dectin-2KO mice. Finally, the disrupted lysates of C. neoformans, but not of whole yeast cells, activated Dectin-2-triggered signaling in an assay with nuclear factor of activated T cells (NFAT)-green fluorescent protein (GFP) reporter cells expressing this receptor. These results suggest that Dectin-2 may oppose the Th2 response and IL-4-dependent mucin production in the lungs after infection with C. neoformans, and it may not be required for the production of Th1, Th17, and proinflammatory cytokines or for clearance of this fungal pathogen.

Multifaceted functions displayed by both pro‐ and anti‐inflammatory properties of chitosan hinder its effective development as an immunomodulatory agent. Herein, the contributions of the bending stiffness of chitosan with regard to its immune regulatory properties toward inflammation are investigated. The anti‐inflammatory properties of chitosan molecular weight (MW) with a shorter (≈1 kDa) or longer (≈15 kDa) than the persistent length (LP) are compared using immunological assays and nanomechanics‐based experiments on the surface forces apparatus (SFA). Interestingly, 1 kDa chitosan significantly enhances the generation of anti‐inflammatory regulatory T cells (Tregs) through the Dectin‐1‐dependent pattern recognition receptor (PRR) on antigen‐presenting cells. SFA analyses also show a similar trend of interaction forces between chitosan and diverse PRRs depending on their MW. The results obtained in the immunological and nanomechanical experiments are consistent and imply that the binding features of PRRs vary depending on the MW of chitosan, which may alter immune activity. In accordance, in vivo administration of only 1 kDa represses inflammatory responses and suppresses the progression of experimental colitis. This study elucidates a previously unexplored bending stiffness‐dependent immune regulatory property of chitosan and suggests the applicability of low MW (rod‐like) chitosan as a pharmaceutical ingredient to treat diverse inflammatory disorders. Mutually exclusive immune responses appear in chitosan. However, most studies investigating chitosan‐mediated immune responses have thus far focused on innate immune cells only. Here, the combination of innate and adaptive immune studies, in vivo studies, and nanomechanical studies provides a new perspective on the utility of size‐based fractionation of chitosan as a therapeutic module against inflammatory diseases.

Hematopoietic cell transplantation has proven beneficial for various intractable diseases, but it remains unclear how hematopoietic stem/progenitor cells (HSPCs) home to the bone marrow (BM) microenvironment, initiate hematopoietic reconstitution, and maintain life‐long hematopoiesis. The use of newly elucidated molecular determinants for overall HSPC engraftment should benefit patients. Here, we report that modification of C‐X‐C chemokine receptor type 4 (Cxcr4) signaling in murine HSPCs does not significantly affect initial homing/lodging events, but leads to alteration in subsequent BM repopulation kinetics, with observations confirmed by both gain‐ and loss‐of‐function approaches. By using C‐terminal truncated Cxcr4 as a gain‐of‐function effector, we demonstrated that signal augmentation likely led to favorable in vivo repopulation of primitive cell populations in BM. These improved features were correlated with enhanced seeding efficiencies in stromal cell cocultures and altered ligand‐mediated phosphorylation kinetics of extracellular signal‐regulated kinases observed in Cxcr4 signal‐augmented HSPCs in vitro. Unexpectedly, however, sustained signal enhancement even with wild‐type Cxcr4 overexpression resulted in impaired peripheral blood (PB) reconstitution, most likely by preventing release of donor hematopoietic cells from the marrow environment. We thus conclude that timely regulation of Cxcr4/CXCR4 signaling is key in providing donor HSPCs with enhanced repopulation potential following transplantation, whilst preserving the ability to release HSPC progeny into PB for improved transplantation outcomes. StemCells2014;32:1929–1942

Inflammatory dilated cardiomyopathy (DCMi) is a major cause of heart failure in individuals below the age of 40. We recently reported that IL-17A is required for the development of DCMi. We show a novel pathway connecting IL-17A, cardiac fibroblasts (CFs), GM-CSF, and heart-infiltrating myeloid cells with the pathogenesis of DCMi. Il17ra−/− mice were protected from DCMi, and this was associated with significantly diminished neutrophil and Ly6Chi monocyte/macrophage (MO/MΦ) cardiac infiltrates. Depletion of Ly6Chi MO/MΦ also protected mice from DCMi. Mechanistically, IL-17A stimulated CFs to produce key chemokines and cytokines that are critical downstream effectors in the recruitment and differentiation of myeloid cells. Moreover, IL-17A directs Ly6Chi MO/MΦ in trans toward a more proinflammatory phenotype via CF-derived GM-CSF. Collectively, this IL-17A–fibroblast–GM-CSF–MO/MΦ axis could provide a novel target for the treatment of DCMi and related inflammatory cardiac diseases.

ABSTRACTCaspase recruitment domain-containing protein 9 (CARD9) is an adaptor molecule signal that is critical for NF-?B activation and is triggered through C-type lectin receptors (CLRs), which are pattern recognition receptors that recognize carbohydrate structures. Previous studies have reported that Cryptococcus neoformans, a fungal pathogen that causes meningoencephalitis in AIDS patients, is recognized through some CLRs, such as mannose receptors or DC-SIGN. However, the role of CARD9 in the host defense against cryptococcal infection remains to be elucidated. In the present study, we analyzed the role of CARD9 in the host defense against pulmonary infection with C. neoformans. CARD9 gene-disrupted (knockout [KO]) mice were highly susceptible to this infection, as shown by the reduced fungal clearance in the infected lungs of CARD9 KO mice, compared to that in wild-type (WT) mice. Gamma interferon (IFN-?) production was strongly reduced in CARD9 KO mice during the innate-immunity phase of infection. Reduced IFN-? synthesis was due to impaired accumulation of NK and memory phenotype T cells, which are major sources of IFN-? innate-immunity-phase production; a reduction in the accumulation of these cells was correlated with reduced CCL4, CCL5, CXCL9, and CXCL10 synthesis. However, differentiation of Th17 cells, but not of Th1 cells, was impaired at the adaptive-immunity phase in CARD9 KO mice compared to WT mice, although there was no significant difference in the infection susceptibility between interleukin 17A (IL-17A) KO and WT mice. These results suggest that CARD9 KO mice are susceptible to C. neoformansinfection probably due to the reduced accumulation of IFN-?-expressing NK and memory phenotype T cells at the early stage of infection.

It is now established that IL-17 has a broad pro-inflammatory potential in mammalian host defense, in inflammatory disease and in autoimmunity, whereas little is known about its anti-inflammatory potential and inhibitory feedback mechanisms. Here, we examined whether IL-17A can inhibit the extracellular release of IL-23 protein, the upstream regulator of IL-17A producing lymphocyte subsets, that is released from macrophages during pulmonary inflammation. We characterized the effect of IL-17A on IL-23 release in several models of pulmonary inflammation, evaluated the presence of IL-17 receptor A (RA) and C (RC) on human alveolar macrophages and assessed the role of the Rho family GTPase Rac1 as a mediator of the effect of IL-17A on the release of IL-23 protein. In a model of sepsis-induced pneumonia, intravenous exposure to Staphylococcus aureus caused higher IL-23 protein concentrations in cell-free bronchoalveolar lavage (BAL) samples from IL-17A knockout (KO) mice, compared with wild type (WT) control mice. In a model of Gram-negative airway infection, pre-treatment with a neutralizing anti-IL-17A Ab and subsequent intranasal (i.n.) exposure to LPS caused higher IL-23 and IL-17A protein concentrations in BAL samples compared with mice exposed to LPS, but pre-treated with an isotype control Ab. Moreover, i.n. exposure with IL-17A protein per se decreased IL- 23 protein concentrations in BAL samples. We detected IL-17RA and IL-17RC on human alveolar macrophages, and found that in vitro stimulation of these cells with IL-17A protein, after exposure to LPS, decreased IL-23 protein in conditioned medium, but not IL-23 p19 or p40 mRNA. This study indicates that IL-17A can partially inhibit the release of IL-23 protein during pulmonary inflammation, presumably by stimulating the here demonstrated receptor units IL-17RA and IL-17RC on alveolar macrophages. Hypothetically, the demonstrated mechanism may serve as negative feedback to protect from excessive IL-17A signaling and to control antibacterial host defense once it is activated.

SMAP2 is an Arf GAP and modulates clathrin-coated vesicle formation. SMAP2-deficient male mice exhibited globozoospermia due to acrosome deformation. In SMAP2(−/−) spermatids, budding of proacrosomal vesicles from the TGN was distorted and clathrin traffic–related molecules such as CALM and syntaxin2 were mislocated.

We have recently identified T cells as important mediators of ischemic brain damage, but the contribution of the different T-cell subsets is unclear. Forkhead box P3 (FoxP3)–positive regulatory T cells (Tregs) are generally regarded as prototypic anti-inflammatory cells that maintain immune tolerance and counteract tissue damage in a variety of immune-mediated disorders. In the present study, we examined the role of Tregs after experimental brain ischemia/reperfusion injury. Selective depletion of Tregs in the DEREG mouse model dramatically reduced infarct size and improved neurologic function 24 hours after stroke and this protective effect was preserved at later stages of infarct development. The specificity of this detrimental Treg effect was confirmed by adoptive transfer experiments in wild-type mice and in Rag1−/−mice lacking lymphocytes. Mechanistically, Tregs induced microvascular dysfunction in vivo by increased interaction with the ischemic brain endothelium via the LFA-1/ICAM-1 pathway and platelets and these findings were confirmed in vitro. Ablation of Tregs reduced microvascular thrombus formation and improved cerebral reperfusion on stroke, as revealed by ultra-high-field magnetic resonance imaging at 17.6 Tesla. In contrast, established immunoregulatory characteristics of Tregs had no functional relevance. We define herein a novel and unexpected role of Tregs in a primary nonimmunologic disease state.

We have recently identified T cells as important mediators of ischemic brain damage, but the contribution of the different T-cell subsets is unclear. Forkhead box P3 (FoxP3)–positive regulatory T cells (Tregs) are generally regarded as prototypic anti-inflammatory cells that maintain immune tolerance and counteract tissue damage in a variety of immune-mediated disorders. In the present study, we examined the role of Tregs after experimental brain ischemia/reperfusion injury. Selective depletion of Tregs in the DEREG mouse model dramatically reduced infarct size and improved neurologic function 24 hours after stroke and this protective effect was preserved at later stages of infarct development. The specificity of this detrimental Treg effect was confirmed by adoptive transfer experiments in wild-type mice and in Rag1−/− mice lacking lymphocytes. Mechanistically, Tregs induced microvascular dysfunction in vivo by increased interaction with the ischemic brain endothelium via the LFA-1/ICAM-1 pathway and platelets and these findings were confirmed in vitro. Ablation of Tregs reduced microvascular thrombus formation and improved cerebral reperfusion on stroke, as revealed by ultra-high-field magnetic resonance imaging at 17.6 Tesla. In contrast, established immunoregulatory characteristics of Tregs had no functional relevance. We define herein a novel and unexpected role of Tregs in a primary nonimmunologic disease state.

Fluorescence can be harnessed to monitor microbial fate and to investigate functional outcomes of individual microbial cell-host cell encounters at portals of entry in native tissue environments. We illustrate this concept by introducing fluorescent Aspergillusreporter (FLARE) conidia that simultaneously report phagocytic uptake and fungal viability during cellular interactions with the murine respiratory innate immune system. Our studies using FLARE conidia reveal stepwise and cell-type-specific requirements for CARD9 and Syk, transducers of C-type lectin receptor and integrin signals, in neutrophil recruitment, conidial uptake, and conidial killing in the lung. By achieving single-event resolution in defined leukocyte populations, the FLARE method enables host cell profiling on the basis of pathogen uptake and killing and may be extended to other pathogens in diverse model host organisms to query molecular, cellular, and pharmacologic mechanisms that shape host-microbe interactions.

Interleukin (IL) 17A, a key cytokine of TH17 cells, is a well-known proinflammatory cytokine. Despite the important role of TH17 cells in acute airway inflammation, the role of IL-17A in allergic rhinitis (AR) remains unclear.

Interleukin-17 (IL-17) is a key factor in T helper type 17 (Th17) lineage host responses and plays critical roles in immunological control of a variety of infectious diseases. Although Legionella pneumophila, an intracellular bacterium found widely in the environment, often causes a serious and life-threatening pneumonia in humans, the contribution of IL-17 to immune function during Legionella pneumonia is unknown. In the present study, we used an experimental Legionella pneumonia infection to clarify the role of IL-17 in the resulting immune response. We observed robust production of pulmonary IL-17A and IL-17F (IL-17A/F), peaking on day 1 and declining thereafter. Upregulated production of tumor necrosis factor alpha (TNF-α), IL-6, and IL-1β, but not monocyte chemotactic protein 1 (MCP-1), was observed in Legionella-infected bone marrow-derived macrophages from BALB/c mice that had been stimulated with IL-17A or IL-17F. A significant decrease in the production of proinflammatory cytokines IL-6 and TNF-α was observed in IL-17A/F-deficient mice (BALB/c background) infected with L. pneumophila. Moreover, we found impaired neutrophil migration and lower numbers of chemokines (KC, LIX, and MIP-2) in IL-17A/F-deficient mice. IL-17A/F-deficient mice also eliminated L. pneumophila more slowly and were less likely to survive a lethal challenge. These results demonstrate that IL-17A/F plays a critical role in L. pneumophila pneumonia, probably through induction of proinflammatory cytokines and accumulation of neutrophils at the infection site.

Interleukin-17 (IL-17) is a key factor in T helper type 17 (Th17) lineage host responses and plays critical roles in immunological control of a variety of infectious diseases. Although Legionella pneumophila, an intracellular bacterium found widely in the environment, often causes a serious and life-threatening pneumonia in humans, the contribution of IL-17 to immune function during Legionellapneumonia is unknown. In the present study, we used an experimental Legionellapneumonia infection to clarify the role of IL-17 in the resulting immune response. We observed robust production of pulmonary IL-17A and IL-17F (IL-17A/F), peaking on day 1 and declining thereafter. Upregulated production of tumor necrosis factor alpha (TNF-a), IL-6, and IL-1ß, but not monocyte chemotactic protein 1 (MCP-1), was observed in Legionella-infected bone marrow-derived macrophages from BALB/c mice that had been stimulated with IL-17A or IL-17F. A significant decrease in the production of proinflammatory cytokines IL-6 and TNF-a was observed in IL-17A/F-deficient mice (BALB/c background) infected with L. pneumophila. Moreover, we found impaired neutrophil migration and lower numbers of chemokines (KC, LIX, and MIP-2) in IL-17A/F-deficient mice. IL-17A/F-deficient mice also eliminated L. pneumophilamore slowly and were less likely to survive a lethal challenge. These results demonstrate that IL-17A/F plays a critical role in L. pneumophilapneumonia, probably through induction of proinflammatory cytokines and accumulation of neutrophils at the infection site.

The mechanism by which thrombotic vessel occlusion occurs independently of plaque development or endothelial cell (EC) disruption remains unclear, largely because of an inability to visualize the formation of thrombus, especially at the single-platelet level in real time. Here we demonstrate that rapidly developing thrombi composed of discoid platelets can be induced in the mesenteric capillaries, arterioles, and large-sized arteries of living mice, enabling characterization of the kinetics of thrombosis initiation and the multicellular interrelationships during thrombus development. Platelet aggregation without EC disruption was triggered by reactive oxygen species (ROS) photochemically induced by moderate power laser irradiation. The inflammatory cytokines TNF-α and IL-1 could be key components of the EC response, acting through regulation of VWF mobilization to the cell surface. Thrombus formation was then initiated by the binding of platelet GPIbα to endothelial VWF in our model, and this effect was inhibited by the ROS scavenger N-acetylcysteine. Actin linker talin-dependent activation of alphaIIb-beta3 integrin or Rac1 in platelets was required for late-phase thrombus stability. Our novel imaging technology illustrates the molecular mechanism underlying inflammation-based thrombus formation by discoid platelets on undisrupted ECs and suggests control of ROS could be a useful therapeutic target for the prevention of thrombotic diseases.

The mechanism by which thrombotic vessel occlusion occurs independently of plaque development or endothelial cell (EC) disruption remains unclear, largely because of an inability to visualize the formation of thrombus, especially at the single-platelet level in real time. Here we demonstrate that rapidly developing thrombi composed of discoid platelets can be induced in the mesenteric capillaries, arterioles, and large-sized arteries of living mice, enabling characterization of the kinetics of thrombosis initiation and the multicellular interrelationships during thrombus development. Platelet aggregation without EC disruption was triggered by reactive oxygen species (ROS) photochemically induced by moderate power laser irradiation. The inflammatory cytokines TNF-α and IL-1 could be key components of the EC response, acting through regulation of VWF mobilization to the cell surface. Thrombus formation was then initiated by the binding of platelet GPIbα to endothelial VWF in our model, and this effect was inhibited by the ROS scavenger N-acetylcysteine. Actin linker talin-dependent activation of alphaIIb-beta3 integrin or Rac1 in platelets was required for late-phase thrombus stability. Our novel imaging technology illustrates the molecular mechanism underlying inflammation-based thrombus formation by discoid platelets on undisrupted ECs and suggests control of ROS could be a useful therapeutic target for the prevention of thrombotic diseases.

Interleukin 1 receptor antagonist (IL-1Ra)-deficient BALB/c mice develop spontaneous arthritis resembling human rheumatoid arthritis. We herein report that infection with Toxoplasma gondii, an intracellular protozoan, is capable of ameliorating the spontaneous development of arthritis in IL-1Ra-deficient mice. The onset of arthritis development was delayed and the severity score of arthritis was significantly suppressed in T. gondii-infected mice. Expression of IL-12p40 mRNA from CD11c+cells of mesenteric lymph nodes (mLN) and spleen markedly increased at 1 week after peroral infection. While CD11c+cells also produced IL-10, IL-1β, and IL-6, CD4+T cells from T. gondii-infected mice expressed significantly high levels of T-bet and gamma interferon (IFN-γ) mRNA in both mLN and spleen. Levels of GATA-3/IL-4 mRNA or RORγt/IL-17 mRNA decreased in the infected mice, indicating Th1 cell polarization and the reduction of Th2 and Th17 cell polarization. The severity of arthritis was related to Th1 cell polarization accompanied by Th17 cell reduction, demonstrating the protective role of the T. gondii-derived Th1 response against Th17 cell-mediated arthritis in IL-1Ra-deficient mice.

ABSTRACTInterleukin 1 receptor antagonist (IL-1Ra)-deficient BALB/c mice develop spontaneous arthritis resembling human rheumatoid arthritis. We herein report that infection with Toxoplasma gondii, an intracellular protozoan, is capable of ameliorating the spontaneous development of arthritis in IL-1Ra-deficient mice. The onset of arthritis development was delayed and the severity score of arthritis was significantly suppressed in T. gondii-infected mice. Expression of IL-12p40 mRNA from CD11c+cells of mesenteric lymph nodes (mLN) and spleen markedly increased at 1 week after peroral infection. While CD11c+cells also produced IL-10, IL-1ß, and IL-6, CD4+T cells from T. gondii-infected mice expressed significantly high levels of T-bet and gamma interferon (IFN-?) mRNA in both mLN and spleen. Levels of GATA-3/IL-4 mRNA or ROR?t/IL-17 mRNA decreased in the infected mice, indicating Th1 cell polarization and the reduction of Th2 and Th17 cell polarization. The severity of arthritis was related to Th1 cell polarization accompanied by Th17 cell reduction, demonstrating the protective role of the T. gondii-derived Th1 response against Th17 cell-mediated arthritis in IL-1Ra-deficient mice.

Chronic GVHD (cGVHD) is a main cause of late death and morbidity after allogeneic hematopoietic cell transplantation, but its pathogenesis remains unclear. We investigated the roles of Th subsets in cGVHD with the use of a well-defined mouse model of cGVHD. In this model, development of cGVHD was associated with up-regulated Th1, Th2, and Th17 responses. Th1 and Th2 responses were up-regulated early after BM transplantation, followed by a subsequent up-regulation of Th17 cells. Significantly greater numbers of Th17 cells were infiltrated in the lung and liver from allogeneic recipients than those from syngeneic recipients. We then evaluated the roles of Th1 and Th17 in cGVHD with the use of IFN-γ–deficient and IL-17–deficient mice as donors. Infusion of IFN-γ−/− or IL-17−/− T cells attenuated cGVHD in the skin and salivary glands. Am80, a potent synthetic retinoid, regulated both Th1 and Th17 responses as well as TGF-β expression in the skin, resulting in an attenuation of cutaneous cGVHD. These results suggest that Th1 and Th17 contribute to the development of cGVHD and that targeting Th1 and Th17 may therefore represent a promising therapeutic strategy for preventing and treating cGVHD.

Chronic GVHD (cGVHD) is a main cause of late death and morbidity after allogeneic hematopoietic cell transplantation, but its pathogenesis remains unclear. We investigated the roles of Th subsets in cGVHD with the use of a well-defined mouse model of cGVHD. In this model, development of cGVHD was associated with up-regulated Th1, Th2, and Th17 responses. Th1 and Th2 responses were up-regulated early after BM transplantation, followed by a subsequent up-regulation of Th17 cells. Significantly greater numbers of Th17 cells were infiltrated in the lung and liver from allogeneic recipients than those from syngeneic recipients. We then evaluated the roles of Th1 and Th17 in cGVHD with the use of IFN-γ–deficient and IL-17–deficient mice as donors. Infusion of IFN-γ−/−or IL-17−/−T cells attenuated cGVHD in the skin and salivary glands. Am80, a potent synthetic retinoid, regulated both Th1 and Th17 responses as well as TGF-β expression in the skin, resulting in an attenuation of cutaneous cGVHD. These results suggest that Th1 and Th17 contribute to the development of cGVHD and that targeting Th1 and Th17 may therefore represent a promising therapeutic strategy for preventing and treating cGVHD.

Kjellmaniella crassifoliaMiyabe (gagome) is a brown alga. Oral gagome administration (oral gagome) resulted in significant upregulation of IL-10 and IFNγ production by Peyer’s patch cells. To assess the adjuvant activity of oral gagome, treated mice were subcutaneously injected with ovalbumin (OVA). The production of cytokines from antigen (Ag)-specific T cells in draining lymph nodes (dLN) and their proliferative response were significantly increased as compared with the control group. These enhancements were associated with increased CD44hiCD62L−activated/memory T cells in dLN as well as upregulation of Ag-specific IgA level in luminal contents. No upregulation of cytokine production by dLN T cells was observed in dectin-1-deficient mice, suggesting that the effect of gagome on cytokine production is largely dependent on the dectin-1 pathway despite its composite constituents. Our findings indicate that gagome is an effective immunomodulator and a potent adjuvant for both the intestinal and the systemic immune response.