International Immunology - Advance Access

The probiotic Escherichia coli strain Nissle 1917 induces {gamma}{delta} T cell apoptosis via caspase- and FasL-dependent pathways

Guzy, C., Paclik, D., Schirbel, A., Sonnenborn, U., Wiedenmann, B., Sturm, A. — 2008-04-30

Human T cells play a vital role in the innate and adaptive immune response to microbial antigens by acting as antigen-presenting cells while at the same time being capable of directly activating CD4⁺ T cells. Pathogenic microbes or loss of tolerance toward the host's own microflora trigger many diseases including inflammatory bowel diseases. We previously demonstrated that Escherichia coli Nissle 1917 directly interacts with the adaptive immune system by regulating central T cell functions. Here we aimed to investigate whether E. coli Nissle regulates T cell function, thereby linking the innate and adaptive immune system. In our study, we demonstrate that, in contrast to the other probiotic strains tested, E. coli Nissle increased activation, cell cycling and expansion of , but not β T cells. In T cells, E. coli Nissle reduced tumor necrosis factor- secretion but increased IL-6 and CXCL8 release. However, after activation, only E. coli Nissle induced T cell apoptosis, mediated via Toll-like receptor-2 by caspase- and FasLigand-dependent pathways. T cells play an important role in the recognition of microbial antigens and the perpetuation of inflammatory processes. The demonstration that E. coli Nissle, but not the other bacteria tested, profoundly regulate T cell function contributes to explaining the biological function of this probiotic strain in inflammatory diseases and provides us with a better understanding of the role of T cells.

CD4+ T cell hyper-responsiveness in CD45 transgenic mice is independent of isoform

Salmond, R. J., McNeill, L., Holmes, N., Alexander, D. R. — 2008-04-30

The CD45 tyrosine phosphatase is required for T cell development and function by virtue of its role as a positive regulator of src family kinase activity. In addition, recent data have highlighted that CD45 also acts as a negative regulator of Lck function by dephosphorylation of critical tyrosine residues. Lck functionality and TCR responsiveness are elevated in transgenic mice expressing the CD45RO isoform at ‘intermediate’ (10–40% of wild type) levels, indicating that the expression level of CD45 is critical in determining the sensitivity of T cells to TCR stimulation. However, it is unclear whether such a phenotype is specific for the CD45RO isoform, typically expressed by activated T cells. In the present work, the roles of three isoforms of CD45, RO, RB and RABC, in thymocyte development, T cell responses and TCR signalling pathways were directly compared. The data demonstrate that expression of CD45RB or CD45RABC at intermediate levels also results in CD4⁺ T cell hyper-reactivity, as previously published for CD45RO. These data emphasize the dual functions of CD45 as both a positive and a negative regulators of TCR signalling irrespective of specific isoform expression.

Combination treatment with IL-2 and anti-IL-2 mAbs reduces tumor metastasis via NK cell activation

Jin, G., Hirano, T., Murakami, M. — 2008-04-30

Combination treatment consisting of IL-2 together with anti-IL-2 mAbs results in markedly larger increases in the numbers of CD8⁺ T cells, dendritic cells (DCs) and NK cells in vivo compared with the results observed with injections of IL-2 or the antibodies alone. We previously showed that this combination treatment overcomes the problems associated with the short half-life of IL-2 in vivo. Importantly, the combination treatment but not IL-2 or the anti-IL-2 mAbs alone protected the mice against tumor metastases in the lungs. Here we have investigated which cell types are responsible for this protective immunity against tumors. We analyzed tumor metastases in mice that were depleted of DCs, CD8⁺ T cells or NK cells. DC-deficient, diphtheria toxin receptor-expressing mice injected with diphtheria toxin as well as B cell- and T cell-deficient RAG-2-knockout mice were protected against tumors after they were administered the combination treatment. On the other hand, mice that were depleted of NK cells using anti-asialo-GM1 antibodies did not exhibit the anti-tumor activity after treatment with IL-2 combined with anti-IL-2 mAbs. Thus, these data demonstrate that NK cells, but not DCs, or CD8⁺ T cells mediate the anti-tumor effect induced by this combination treatment. Therefore, combining neutralizing anti-IL-2 mAbs with IL-2 may be clinically useful to effectively enhance IL-2-mediated NK cell activities.

Bam32: a novel mediator of Erk activation in T cells

2008-04-29

Bam32 (B lymphocyte adapter molecule of 32 kDa) is an adapter protein expressed in some hematopoietic cells including B and T lymphocytes. It was previously shown that Bam32-deficient mice have defects in various aspects of B cell activation including B cell receptor (BCR)-induced Erk activation, BCR-induced proliferation and T-independent antibody responses. In this study, we have examined the role of Bam32 in T cell activation using Bam32-deficient mice. By comparing CD4⁺ T cells from lymph nodes of wild-type and Bam32-deficient mice, we found that Bam32 was required for optimal TCR-induced Erk activation, cytokine production, proliferation and actin-mediated spreading of CD4⁺ T cells. These results indicate a novel pathway to Erk activation in T cells involving the adapter protein Bam32.

Administration of IL-33 induces airway hyperresponsiveness and goblet cell hyperplasia in the lungs in the absence of adaptive immune system

2008-04-29

Systemic administration of IL-18 induces polyclonal IgE responses by causing NKT cells to express CD40 ligand and to produce IL-4. Administration of IL-33 also induces IgE response, although the mechanism underlying IgE response is unclear. Here, we compared the effects of IL-18 and IL-33 on bone marrow-derived mast cells and basophils as well as non-polarized and T_h2-polarized CD4⁺ T cells in vitro. Basophils, comprising IL-18R⁺ cells (14.2%) and IL-33R⁺ cells (34.6%), and mast cells, comprising IL-18R⁺ cells (2.0%) and IL-33R⁺ cells (95.6%), produce IL-4, IL-6, IL-13, granulocyte macrophage colony-stimulating factor (GM-CSF) and chemokines (RANTES, MIP-1, MIP-1β and MCP-1), upon stimulation with IL-18 and/or IL-33 in the presence of IL-3. Only basophils strongly produce IL-4. Furthermore, compared with mast cells, basophils produce larger amounts of the above cytokines and chemokines in response to IL-33. Level of IL-33Rβ-mRNA expression in basophils is higher than that in mast cells. Effect of IL-33 is dependent on ST2 binding, and its signal is transduced via MyD88 in vitro. We also found that IL-2 plus IL-18 or IL-33 alone stimulates non-polarized or T_h2-polarized CD4⁺ T cells to produce IL-4 and IL-13 or IL-5 and IL-13, respectively. We finally showed that administration of IL-33 into mice ST2/MyD88 dependently induces airway hyperresponsiveness (AHR) and goblet cell hyperplasia by induction of IL-4, IL-5 and IL-13 in the lungs. Furthermore, same treatment of RAG-2^–/– mice, lacking T and B cells, more strikingly induced AHR with marked goblet cell hyperplasia and eosinophilic infiltration in the lungs. Thus, IL-33 induces asthma-like symptom entirely independent of acquired immune system.

Potentiation of NK cell-mediated cytotoxicity in human lung adenocarcinoma: role of NKG2D-dependent pathway

2008-04-25

Natural cytotoxicity receptors and NKG2D correspond to major activating receptors involved in triggering of tumor cell lysis by human NK cells. In this report, we investigated the expression of NKG2D ligands (NKG2DLs), MHC class I-related chain (MIC) A, MICB and UL16-binding proteins 1, 2 and 3, on a panel of human non-small-cell lung carcinoma cell lines, and we analyzed their role in tumor cell susceptibility to NK cell lysis. Although adenocarcinoma (ADC) cells expressed heterogeneous levels of NKG2DLs, they were often resistant to NK cell-mediated killing. Resistance of a selected cell line, ADC-Coco, to allogeneic polyclonal NK cells and autologous NK cell clones correlated with shedding of NKG2DLs resulting from a matrix metalloproteinase (MMP) production. Treatment of ADC-Coco cells with a MMP inhibitor (MMPI) combined with IL-15 stimulation of autologous NK cell clones lead to a potentiation of NK cell-mediated cytotoxicity. This lysis is mainly NKG2D mediated, since it is abrogated by anti-NKG2D-neutralizing mAb. These results suggest that MMPIs, in combination with IL-15, may be useful for overcoming tumor cell escape from the innate immune response.

Osteoclasts support the survival of human plasma cells in vitro

Geffroy-Luseau, A., Jego, G., Bataille, R., Campion, L., Pellat-Deceunynck, C. — 2008-04-08

The aim of this in vitro study was to evaluate if osteoclasts (OCs) and dendritic cells (DCs), both of monocyte origin, can support the survival of normal human plasma cells (PCs). PCs differentiate from plasmablasts (PBs) arising from activated B cells, essentially memory B cells. To study the survival of both PBs (CD20^lowCD38^highCD138^neg) and PCs (CD20^negCD38^brightCD138^bright), we generated pre-PBs (CD20^lowCD38^posCD138^neg) from CD40-activated B cells (CD20^highCD38^negCD138^neg) and cultured them on DCs or OCs in the presence of added IL-6. By quantitative and qualitative study, we showed that DCs support the survival of PBs and early PCs, but not that of PCs. In contrast, OCs support the survival of PBs, early PCs and PCs. PCs surviving on OCs 12 days after pre-PB input display phenotypic features of bone marrow PCs, CD138^brightCD38^brightHLA-DR^lowCD45^dim. The ability for OCs to support the survival of PCs was fully dependent on cell–cell contact and not inhibited by BCMA-Fc suggesting that secreted BAFF and APRIL were not involved.

Delta-like 1 is essential for the maintenance of marginal zone B cells in normal mice but not in autoimmune mice

2008-04-01

Notch2 and Delta-like 1 (Dll1) have been implicated in the development of marginal zone B (MZB) cells. In the present study, we characterized the expression and function of mouse Notch receptors and ligands in the spleen by using newly generated mAbs. Although Notch2 was expressed on both B and T cells in the spleen, the highest expression was observed on precursors of marginal zone B and MZB cells. Dll1 was expressed on macrophage and erythroblasts in the red pulp, but not on B cells or marginal zone macrophage. Administration of a blocking mAb against Dll1 not only blocked the development of MZB cells in juvenile mice but also gradually depleted the pre-established MZB cells in adult mice, indicating a critical role for Dll1 in the maintenance of MZB cells in the spleen of normal mice. Interestingly, Dll1 was not necessary for the maintenance of MZB cells in lupus-prone (NZB x NZW) F1 mice particularly after the onset of the disease, suggesting that the Dll1 independence may be a feature of dysregulated MZB cells producing auto-antibodies.

Suppressor of cytokine signaling-1 ameliorates dextran sulfate sodium-induced colitis in mice

2008-04-01

Inflammatory bowel disease (IBD) is a chronic disorder of the gastrointestinal tract. Although the etiology and pathogenesis of IBD remain unknown, pro-inflammatory cytokines including IFN- play an important role in the development of IBD. Suppressor of cytokine signaling-1 (SOCS-1) is a crucial inhibitor of cytokine signaling, particularly of IFN-. In this study, we investigated the role of SOCS-1 in the development of murine dextran sulfate sodium (DSS)-induced colitis, a model of colitis resembling human IBD. SOCS-1 heterozygous (SOCS-1^+/–) and wild-type (WT) mice were given 3% DSS dissolved in drinking water for 5 days. Activation and expression of signal transducers and activators of transcription (STAT) in colonic tissues were assessed by western blot analysis. The expression of CD4, IFN-, IL-4, IL-17 and Forkhead box P3 (Foxp3) in colonic lamina propria lymphocytes was analyzed by flow cytometry and cytokine concentrations in serum were measured. DSS-treated SOCS-1^+/– mice developed more severe colitis than DSS-treated WT mice. Enhanced activation of STAT1, a higher ratio of CD4⁺IFN-⁺ T cells and a lower frequency of Foxp3⁺ regulatory T (Treg) cells, were observed in the colon of DSS-treated SOCS-1^+/– mice compared with DSS-treated WT mice. DSS-treated SOCS-1^+/– mice showed higher levels of IFN- in sera than did DSS-treated WT mice. Furthermore, T cell-specific SOCS-1-conditional knockout mice developed more severe colitis than control mice after DSS administration. Our findings suggest that SOCS-1, particularly in T cells, prevents the development of DSS-induced colitis in mice by inhibiting IFN-/STAT1 signaling and by subsequently regulating Treg cell development.

Strain distribution pattern of immune nephritis--a follow-up study

2008-04-01

Previous studies have indicated that the NZW, DBA/1, 129/sv and BUB strains are particularly sensitive to experimental anti-glomerular basement membrane (GBM)-induced immune nephritis. The present study extends previous observations by examining eight additional inbred mouse strains for their susceptibility to immune nephritis. Unlike the ALR/Lt, CAST/Ei, DDY/JclSidSeyFrk, FVB/NJ, PERA/Ei, SB/Le and BALB/c strains, the C58 mouse strain was observed to be particularly susceptible to experimental immune nephritis, with CBA mice being a close second. In contrast to the other strains, C58 mice uniformly developed heavy proteinuria, azotemia and severe glomerulonephritis with prominent crescent formation and tubulointerstitial nephritis following challenge with anti-GBM sera. These differences were associated with increased murine Ig deposition, leukocyte infiltration and IFN- production within the kidneys of C58 mice. Studies aimed at elucidating the genetic factors and molecular pathways responsible for the enhanced renal disease in C58 mice are warranted.

IL-27R deficiency delays the onset of colitis and protects from helminth-induced pathology in a model of chronic IBD

2008-03-28

Members of the IL-6/IL-12 cytokine family play central roles in Crohn's disease. The present findings demonstrate that IL-27, a close relative of IL-12 and IL-23, can promote the onset of colitis in mice. We report that, compared with IL-10-deficient animals, which succumb to chronic intestinal disease at 3-6 months of age, mice lacking both IL-10 and the IL-27R (IL-27R/WSX-1) exhibit delayed pathology and prolonged survival (>1 year). Moreover, unlike highly susceptible IL-10-deficient counterparts, they were able to clear infection with Trichuris muris, a colon-dwelling nematode. In both models of intestinal inflammation, improved clinical outcome was associated with reduced inflammation and profound attenuation of T_h1 responses and, consistent with these in vivo findings, we confirmed that during in vitro differentiation, IL-27 directly promotes CD4⁺ T cell IFN- production through effects on Tbet, a key T_h1 transcription factor. We also found that its ability to suppress T_h2 responses, which was clearly evident in helminth-infected IL-10–/–IL-27R–/– mice, was largely Tbet independent. Taken together, these studies demonstrate that, in the absence of IL-10, IL-27 can promote T_h1-type and suppress T_h2-type intestinal inflammation but, ultimately, is not required for the development of inflammatory bowel disease.

Regulatory role of B-1 B cells in chronic colitis

2008-03-28

According to the ‘hygiene hypothesis’, enhanced microbial exposure due to early childhood infections leads to a reduction of T_h2-mediated allergic diseases and inflammatory bowel disease. To begin to elucidate the mechanisms underlying this hypothesis, we studied development of T_h2-mediated colitis of the TCR knockout (KO) mouse in both a specific pathogen-free (SPF) facility and a conventional (CV) facility. After more than five generations in each facility, TCR KO mice kept in the CV facility developed dramatically less colitis than mice that were kept in the SPF facility. Surprisingly, the suppression of colitis in the CV facility correlated with a significant increase in natural IgM production by B-1 B cells. In contrast, B cell-deficient TCR double-knockout (µ DKO) mice maintained in the CV facility continued to develop severe colitis, strongly suggesting that B-1 B cells contributed to the suppression of colitis. Indeed, the adoptive transfer of B-1 B cells isolated from the peritoneal cavity of TCR KO mice (SPF) into µ DKO mice (CV) suppressed the development of colitis in the recipient mice. We conclude that B-1 cells play a regulatory role in T_h2-mediated colitis under non-hygienic conditions, possibly by generating natural antibodies in response to microbial flora.