Lactoferrin causes IgA and IgG2b isotype switching through betaglycan binding and activation of canonical TGF-β signaling

Jang, Y-S,Seo, G-Y,Lee, J-M,Seo, H-Y,Han, H-J,Kim, S-J,Jin, B-R,Kim, H-J,Park, S-R,Rhee, K-J,Kim, W-S,Kim, P-H Society for Mucosal Immunology 2015 Mucosal immunology Vol.8 No.4

<P>Lactoferrin (LF), a pleiotropic iron-binding glycoprotein, is known to modulate the humoral immune response. However, its exact role in Ig synthesis has yet to be elucidated. In this study, we investigated the effect of LF on Ig production by mouse B cells and its underlying mechanisms. LF, like transforming growth factor (TGF)-beta 1, stimulated B cells to produce IgA and IgG2b, while downregulating other isotypes. Using limiting dilution analysis, LF was shown to increase the frequency of IgA-secreting B-cell clones. This was paralleled by an increase in Ig germ-line alpha (GL alpha) transcripts, indicating that LF plays a role as an IgA switch factor. Interestingly, LF directly interacted with betaglycan (TGF-beta receptor III, T beta RIII) and in turn induced phosphorylation of T beta RI and Smad3 through formation of the T beta RIII/T beta RII/T beta RI complex, leading to IgA isotype switching. Peroral administration of LF increased intestinal/serum IgA production as well as number of IgA plasma cells in lamina propria. Finally, we found that LF has an adjuvant activity when nontoxigenic Salmonella typhimurium was inoculated perorally, conferring protection against intragastrical infection of toxigenic S. typhimurium. These results suggest that LF has an important effect on the mucosal/systemic IgA response and can contribute to protection against intestinal pathogens.</P>

Antigen-bearing dendritic cells from the sublingual mucosa recirculate to distant systemic lymphoid organs to prime mucosal CD8 T cells

Hervouet, C,Luci, C,Bekri, S,Juhel, T,Bihl, F,Braud, V M,Czerkinsky, C,Anjuè,re, F Society for Mucosal Immunology 2014 Mucosal immunology Vol.7 No.2

Effector T cells are described to be primed in the lymph nodes draining the site of immunization and to recirculate to effector sites. Sublingual immunization generates effector T cells able to disseminate to the genital tract. Herein, we report an alternative mechanism that involves the recirculation of antigen-bearing dendritic cells (DCs) in remote lymphoid organs to prime T cells. Sublingual immunization with a muco-adhesive model antigen unable to diffuse through lymphatic or blood vessels induced genital CD8 T cells. The sublingual draining lymph nodes were not mandatory to generate these lymphocytes, and antigen-bearing DCs from distant lymph nodes and spleen were able to prime specific CD8 T cells in a time- and dose-dependent manner. This study demonstrates, for the first time, that antigen-bearing DCs originating from the site of immunization recirculate to distant lymphoid organs and provides insights into the mechanism of distant CD8 T-cell generation by sublingual immunization.

Anti-bacterial and anti-toxic immunity induced by a killed whole-cell-cholera toxin B subunit cholera vaccine is essential for protection against lethal bacterial infection in mouse pulmonary cholera model

Kang, S-S,Yang, J S,Kim, K W,Yun, C-H,Holmgren, J,Czerkinsky, C,Han, S H Society for Mucosal Immunology 2013 Mucosal immunology Vol.6 No.4

The lack of appropriate animal model for studying protective immunity has limited vaccine development against cholera. Here, we demonstrate a pulmonary cholera model conferred by intranasal administration of mice with live Vibrio cholerae. The bacterial components, but not cholera toxin, caused lethal and acute pneumonia by inducing massive inflammation. Intranasal immunization with Dukoral, comprising killed whole bacteria and recombinant cholera toxin B subunit (rCTB), developed both mucosal and systemic antibody responses with protection against the lethal challenge. Either rCTB-free Dukoral or rCTB alone partially protected the mice against the challenge. However, reconstitution of rCTB-free Dukoral with rCTB restored full protection. Parenteral immunization with Dukoral evoked strong systemic immunity without induction of mucosal immunity or protection from the challenge. These results suggest that both anti-bacterial and anti-toxic immunity are required for protection against V. cholerae–induced pneumonia, and this animal model is useful for pre-clinical evaluation of candidate cholera vaccines.

IL-9-producing invariant NKT cells protect against DSS-induced colitis in an IL-4-dependent manner

Kim, H S,Chung, D H Society for Mucosal Immunology 2013 Mucosal immunology Vol.6 No.2

Although the T-helper type 9 (Th9) subset has recently been revisited, interleukin (IL)-9-producing invariant natural killer T (iNKT) cells remain poorly characterized. Moreover, whether IL-9-producing iNKT cells regulate colitis is unknown. Here, we investigated functions of IL-9-producing iNKT cells in dextran sulfate sodium (DSS)-induced colitis. Wild-type (WT) mice attenuated colitis compared to Jα18<SUP>−/−</SUP> mice, which were restored by the adoptive transfer of WT, but not IL-4-deficient iNKT cells. IL-4-deficient iNKT cells failed to produce IL-9, which was reversed by recombinant IL-4. Furthermore, iNKT cells, pre-incubated with anti-CD3+CD28 monoclonal antibodies and IL-4+tumor growth factor (TGF)-β (IL-9<SUP>+</SUP> iNKT), suppressed colitis in Jα18<SUP>−/−</SUP> mice, whereas pre-incubated IL-4-deficient iNKT cells did not. IL-9 blockade reversed IL-9<SUP>+</SUP> iNKT cell-mediated colitis by increasing colonic IL-17A and interferon (IFN)-γ transcripts, but decreasing IL-9, IL-10, TGF-β, PU.1, IFN regulatory factor 4, and signal transducer and activator of transcription 5 in Jα18<SUP>−/−</SUP> mice. In conclusion, IL-9-producing iNKT cells protect against DSS-induced colitis through IFN-γ and IL-17A suppression, but IL-10 and TGF-β enhancement, depending on the IL-4 production by iNKT cells.

Gastrointestinal inflammation by gut microbiota disturbance induces memory impairment in mice

Jang, S-E,Lim, S-M,Jeong, J-J,Jang, H-M,Lee, H-J,Han, M J,Kim, D-H Society for Mucosal Immunology 2018 Mucosal immunology Vol.11 No.2

<P>In this study, we tested our hypothesis regarding mechanistic cross-talk between gastrointestinal inflammation and memory loss in a mouse model. Intrarectal injection of the colitis inducer 2,4,6-trinitrobenzenesulfonic acid (TNBS) in mice caused colitis via activation of nuclear factor (NF)-kappa B and increase in membrane permeability. TNBS treatment increased fecal and blood levels of lipopolysaccharide (LPS) and the number of Enterobacteriaceae, particularly Escherichia coli (EC), in the gut microbiota composition, but significantly reduced the number of Lactobacillus johnsonii (LJ). Indeed, we observed that the mice treated with TNBS displayed impaired memory, as assessed using the Y-maze and passive avoidance tasks. Furthermore, treatment with EC, which was isolated from the feces of mice with TNBS-induced colitis, caused memory impairment and colitis, and increased the absorption of orally administered LPS into the blood. Treatment with TNBS or EC induced NF-kappa B activation and tumor necrosis factor-alpha expression in the hippocampus of mice, as well as suppressed brain-derived neurotrophic factor expression. However, treatment with LJ restored the disturbed gut microbiota composition, lowered gut microbiota, and blood LPS levels, and attenuated both TNBS- and EC-induced memory impairment and colitis. These results suggest that the gut microbiota disturbance by extrinsic stresses can cause gastrointestinal inflammation, resulting in memory impairment.</P>

Interleukin-17A negatively regulates lymphangiogenesis in T helper 17 cell-mediated inflammation

Park, H J,Yuk, C M,Shin, K,Lee, S-H Society for Mucosal Immunology 2018 Mucosal immunology Vol.11 No.3

<P>During inflammation lymphatic vessels (LVs) are enlarged and their density is increased to facilitate the migration of activated immune cells and antigens. However, after antigen clearance, the expanded LVs shrink to maintain homeostasis. Here we show that interleukin (IL)-17A, secreted fromT helper type 17 (T(H)17) cells, is a negative regulator of lymphangiogenesis during the resolution phase of T(H)17-mediated immune responses. Moreover, IL-17A suppresses the expression of major lymphatic markers in lymphatic endothelial cells and decreases in vitro LV formation. To investigate the role of IL-17A in vivo, we utilized a cholera toxin-mediated inflammation model and identified inflammation and resolution phases based on the numbers of recruited immune cells. IL-17A, markedly produced by T(H)17 cells even after the peak of inflammation, was found to participate in the negative regulation of LV formation. Moreover, blockade of IL-17A resulted in not only increased density of LVs in tissues but also their enhanced function. Taken together, these findings improve the current understanding of the relationship between LVs and inflammatory cytokines in pathologic conditions.</P>

MyD88 in donor bone marrow cells is critical for protection from acute intestinal graft-vs.-host disease

Lim, J-Y,Lee, Y-K,Lee, S-E,Ju, J-M,Eom, K-S,Kim, Y-J,Chung, N-G,Jeong, D C,Park, G,Choi, E Y,Min, C-K Society for Mucosal Immunology 2016 Mucosal immunology Vol.9 No.3

<P>To understand the role of myeloid differentiation factor 88 (MyD88) expressed by donor bone marrow (BM) in the pathophysiology of graft-vs.-host disease (GVHD), we investigated the effects of transplantation of MyD88-deficient T cell-depleted BM (MyD88KO TCD-BM) on the severity of GVHD. Transplantation with MyD88KO TCD-BM aggravated GVHD; serious gut damage was evident, with high infiltration of T cells into the intestines of recipients and markedly reduced expansion of CD11b(+)Gr-1(+) myeloid-derived suppressor cells (MDSCs). MDSCs from MyD88KO mice were defective in inducing donor T-cell apoptosis and inhibiting T-cell proliferation. Supplementation of transplanted mice with MDSCs from wild-type mice, but not MyD88KO mice, attenuated GVHD severity with reduced intestinal T-cell infiltration in MyD88KO TCD-BM recipients. Pretreatment of BM donors with lipopolysaccharide to increase MDSC levels and MyD88 transcription in the TCD-BM transplant alleviated GVHD severity and intestinal T-cell infiltration. The T cell/MDSC ratios were correlated with intestinal GVHD severity in both animal models and human patients. This study indicates that MyD88-dependent MDSC expansion from donor BM is critical for protection against fatal intestinal GVHD.</P>

ROS-dependent HMGB1 secretion upregulates IL-8 in upper airway epithelial cells under hypoxic condition

Min, H J,Kim, J-H,Yoo, J E,Oh, J-H,Kim, K S,Yoon, J-H,Kim, C-H Society for Mucosal Immunology 2017 Mucosal immunology Vol.10 No.3

<P>High-mobility group box 1 (HMGB1) mediates various functions according to the location. We tried to investigate the role of HMGB1 in upper airway under hypoxic conditions. We cultured primary normal human nasal epithelium (NHNE) cells under hypoxic conditions and evaluated the movement of HMGB1 by western blotting, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) level was evaluated to estimate the translocation mechanism of HMGB1. The role of secreted HMGB1 was evaluated by ELISA assay. Furthermore, we collected human nasal mucosa samples and nasal lavage fluids from patients conditioned under hypoxic and non-hypoxic environment, and compared the expression of HMGB1 in human nasal mucosa samples by immunohistochemistry and the levels of HMGB1 in lavage fluids using ELISA assay. Hypoxia induced translocation of HMGB1 into the extracellular area and it was dependent on ROS produced by dual oxidase 2. Secreted HMGB1 was involved in the upregulation of interleukin (IL)-8. In human samples, HMGB1 was translocated from nucleus to the cytoplasm in hypoxic-conditioned nasal mucosa. HMGB1 was increased in nasal lavage samples of chronic rhinosinusitis patients, whose sinus mucosa was supposed to be hypoxic as compared with controls. We suggest that HMGB1 is secreted in hypoxic condition via ROS-dependent mechanism and secreted HMGB1 participates in IL-8 upregulation mediating inflammatory response.</P>

Neutrophil pyroptosis mediates pathology of P. aeruginosa lung infection in the absence of the NADPH oxidase NOX2

Ryu, J-C,Kim, M-J,Kwon, Y,Oh, J-H,Yoon, S S,Shin, S J,Yoon, J-H,Ryu, J-H Society for Mucosal Immunology 2017 Mucosal immunology Vol.10 No.3

<P>Nod-like receptor family, CARD domain-containing 4 (NLRC4) inflammasome activation is required for efficient clearance of intracellular pathogens through caspsase-1-dependent pyroptosis in macrophages. Although neutrophils have a critical role in protection from Pseudomonas aeruginosa infection, the mechanisms regulating inflammasome-mediated pyroptosis in neutrophils and its physiological role are largely unknown. We sought to determine the specific mechanisms regulating neutrophil pyroptosis in P. aeruginosa strain PAO1 (PAO1) lung infection and to identify the pathological role of this process. Nox2(-/-) models with reduced neutrophil antibacterial activity exhibited increased neutrophil pyroptosis, which was mediated by flagellin, a pathogenic PAO1 component. We also demonstrate that PAO1-induced pyroptosis depended on NLRC4 and Toll-like receptor 5 (TLR5) in neutrophils generated from Nlrc4(-/-) or Tlr5(-/-) mice. Our study reveals previously unknown mechanisms and physiological role of neutrophil pyroptosis during P. aeruginosa lung infection. Furthermore, our findings regarding neutrophil pyroptosis in the context of neutrophil dysfunction may explain the causes of acute and/or chronic infectious diseases discovered in immune-compromised patients.</P>

Gut commensal Bacteroides acidifaciens prevents obesity and improves insulin sensitivity in mice

Yang, J-Y,Lee, Y-S,Kim, Y,Lee, S-H,Ryu, S,Fukuda, S,Hase, K,Yang, C-S,Lim, H S,Kim, M-S,Kim, H-M,Ahn, S-H,Kwon, B-E,Ko, H-J,Kweon, M-N Society for Mucosal Immunology 2017 Mucosal immunology Vol.10 No.1

<P>In humans, the composition of gut commensal bacteria is closely correlated with obesity. The bacteria modulate metabolites and influence host immunity. In this study, we attempted to determine whether there is a direct correlation between specific commensal bacteria and host metabolism. As mice aged, we found significantly reduced body weight and fat mass in Atg7(Delta CD11c) mice when compared with Atg7(f/f) mice. When mice shared commensal bacteria by cohousing or feces transfer experiments, body weight and fat mass were similar in both mouse groups. By pyrosequencing analysis, Bacteroides acidifaciens (BA) was significantly increased in feces of Atg7(Delta CD11c) mice compared with those of control Atg7(f/f) mice. Wild-type C57BL/6 (B6) mice fed with BA were significantly more likely to gain less weight and fat mass than mice fed with PBS. Of note, the expression level of peroxisome proliferator-activated receptor alpha (PPARa) was consistently increased in the adipose tissues of Atg7(Delta CD11c) mice, B6 mice transferred with fecal microbiota of Atg7(Delta CD11c) mice, and BA-fed B6 mice. Furthermore, B6 mice fed with BA showed elevated insulin levels in serum, accompanied by increased serum glucagon-like peptide-1 and decreased intestinal dipeptidyl peptidase-4. These finding suggest that BA may have potential for treatment of metabolic diseases such as diabetes and obesity.</P>