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Suzuki, Tomoko, Mutsuo Yamaya, Masahito Kamanaka, Yu X. Jia, Katsutoshi Nakayama, Masayoshi Hosoda, Norihiro Yamada, Hidekazu Nishimura, Kiyohisa Sekizawa, and Hidetada Sasaki. Type 2 rhinovirus infection of cultured human tracheal epithelial cells: role of LDL receptor. Am J Physiol Lung Cell Mol Physiol 280: L409-L420, 2001.--To examine the role of the low-density lipoprotein (LDL) receptor on minor group human rhinovirus (RV) infection, primary cultures of human tracheal epithelial cells were infected with a minor group (RV2) or a major group (RV14) RV. Viral infection was confirmed by showing with PCR that viral titers in supernatants and lysates from infected cells increased with time. RV2 and RV14 increased expression of mRNA and protein of the LDL receptor on the cells and the cytokine production. RV2 induced activation of transcription factors SP1 and nuclear factor-[Kappa]B (NF-[Kappa]B). An antibody to the LDL receptor inhibited RV2 infection and RV2-induced cytokine production without an effect on RV14 infection and RV14-induced cytokine production. These findings imply that RV2 upregulates LDL receptor expression on airway epithelial cells, thereby increasing susceptibility to minor group RV infection. LDL receptor expression and cytokine production may be mediated, in part, via activation of transcription factors by RV2. These events may be important in airway inflammation after minor group RV infection in asthma. asthma; common cold; airway inflammation; low-density lipoprotein receptor

Suzuki, Tomoko, Mutsuo Yamaya, Kiyohisa Sekizawa, Norihiro Yamada, Katsutoshi Nakayama, Satoshi Ishizuka, Masahito Kamanaka, Tetsushi Morimoto, Yoshio Numazaki, and Hidetada Sasaki. Effects of dexamethasone on rhinovirus infection in cultured human tracheal epithelial cells. Am. J. Physiol. Lung Cell. Mol. Physiol. 278: L560-L571, 2000.--To examine the effects of glucocorticoid on rhinovirus (RV) infection, primary cultures of human tracheal epithelial cells were infected with either RV2 or RV14. Viral infection was confirmed by demonstrating that viral RNA in infected cells and viral titers of supernatants and lysates from infected cells increased with time. RV14 infection upregulated the expression of mRNA and protein of intercellular adhesion molecule-1 (ICAM-1), the major RV receptor, on epithelial cells, and it increased the production of interleukin (IL)-1[Beta], IL-6, IL-8, and tumor necrosis factor-[Alpha] in supernatants. Dexamethasone reduced the viral titers of supernatants and cell lysates, viral RNA of infected cells, and susceptibility of RV14 infection in association with inhibition of cytokine production and ICAM-1 induction. In contrast to RV14 infection, dexamethasone did not alter RV2 infection, a minor group of RVs. These results suggest that dexamethasone may inhibit RV14 infection by reducing the surface expression of ICAM-1 in cultured human tracheal epithelial cells. Glucocorticoid may modulate airway inflammation via reducing the production of proinflammatory cytokines and ICAM-1 induced by rhinovirus infection. asthma; common cold; airway inflammation; intercellular adhesion molecule-1

Chronic viral infections lead to CD8+ T cell exhaustion, characterized by impaired cytokine secretion. Presence of the immune-regulatory cytokine IL-10 promotes chronicity of Lymphocytic Choriomeningitis Virus (LCMV) Clone 13 infection, while absence of IL-10/IL-10R signaling early during infection results in viral clearance and higher percentages and numbers of antiviral, cytokine producing T cells. IL-10 is produced by several cell types during LCMV infection but it is currently unclear which cellular sources are responsible for induction of viral chronicity. Here, we demonstrate that although dendritic cells produce IL-10 and overall IL-10 mRNA levels decrease significantly in absence of CD11c+ cells, absence of IL-10 produced by CD11c+ cells failed to improve the LCMV-specific T cell response and control of LCMV infection. Similarly, NK cell specific IL-10 deficiency had no positive impact on the LCMV-specific T cell response or viral control, even though high percentages of NK cells produced IL-10 at early time points after infection. Interestingly, we found markedly improved T cell responses and clearance of normally chronic LCMV Clone 13 infection when either myeloid cells or T cells lacked IL-10 production and mice depleted of monocytes/macrophages or CD4+ T cells exhibited reduced overall levels of IL-10 mRNA. These data suggest that the decision whether LCMV infection becomes chronic or can be cleared critically depends on early CD4+ T cell and monocyte/macrophage produced IL-10. [ABSTRACT FROM AUTHOR]

IL-10 is an anti-inflammatory cytokine that regulates the extent of host immunity to infection by exerting suppressive effects on different cell types. Herpes viruses induce IL-10 to modulate the virus-host balance towards their own benefit, resulting in prolonged virus persistence. To define the cellular and molecular players involved in IL-10 modulation of herpes virus-specific immunity, we studied mouse cytomegalovirus (MCMV) infection. Here we demonstrate that IL-10 specifically curtails the MCMV-specific CD4 T cell response by suppressing the bidirectional crosstalk between NK cells and myeloid dendritic cells (DCs). In absence of IL-10, NK cells licensed DCs to effectively prime MCMV-specific CD4 T cells and we defined the pro-inflammatory cytokines IL-12, IFN-γ and TNF-α as well as NK cell activating receptors NKG2D and NCR-1 to regulate this bidirectional NK/DC interplay. Consequently, markedly enhanced priming of MCMV-specific CD4 T cells in Il10-/- mice led to faster control of lytic viral replication, but this came at the expense of TNF-α mediated immunopathology. Taken together, our data show that early induction of IL-10 during MCMV infection critically regulates the strength of the innate-adaptive immune cell crosstalk, thereby impacting beneficially on the ensuing virus-host balance for both the virus and the host. [ABSTRACT FROM AUTHOR]

Various cell types in both lymphoid and non-lymphoid tissues produce the anti-inflammatory cytokine interleukin (IL)-10 during murine cytomegalovirus (MCMV) infection. The functions of IL-10 in the liver during acute infection and the cells that generate this cytokine at this site have not been extensively investigated. In this study, we demonstrate that the production of IL-10 in the liver is elevated in C57BL/6 mice during late acute MCMV infection. Using IL-10 green fluorescence protein (GFP) reporter knock-in mice, designated IL-10- internal ribosomal entry site (IRES)-GFP-enhanced reporter (tiger), NK cells are identified as major IL-10 expressing cells in the liver after infection, along with T cells and other leukocytes. In the absence of IL-10, mice exhibit marked elevations in proinflammatory cytokines and in the numbers of mononuclear cells and lymphocytes infiltrating the liver during this infection. IL-10-deficiency also enhances liver injury without improving viral clearance from this site. Collectively, the results indicate that IL-10-producing cells in the liver provide protection from collateral injury by modulating the inflammatory response associated with MCMV infection. [ABSTRACT FROM AUTHOR]

West Nile virus (WNV), a mosquito-borne single-stranded RNA flavivirus, can cause significant human morbidity and mortality. Our data show that interleukin-10 (IL-10) is dramatically elevated both in vitro and in vivo following WNV infection. Consistent with an etiologic role of IL-10 in WNV pathogenesis, we find that WNV infection is markedly diminished in IL-10 deficient (IL-10-/-) mice, and pharmacologic blockade of IL-10 signaling by IL-10 neutralizing antibody increases survival of WNV-infected mice. Increased production of antiviral cytokines in IL-10-/- mice is associated with more efficient control of WNV infection. Moreover, CD4+ T cells produce copious amounts of IL-10, andmay be an important cellular source of IL-10 during WNV infection in vivo. In conclusion, IL-10 signaling plays a negative role in immunity against WNV infection, and blockade of IL-10 signaling by genetic or pharmacologic means helps to control viral infection, suggesting a novel anti-WNV therapeutic strategy. [ABSTRACT FROM AUTHOR]

Interleukin 23 (IL-23) and IL-17 have been linked to the pathogenesis of several chronic inflammatory disorders, including inflammatory bowel disease. Yet as an important function for IL-23 is emerging, the function of IL-17 in inflammatory bowel disease remains unclear. Here we demonstrate IL-17A-mediated protection in the CD45RBhi transfer model of colitis. An accelerated wasting disease elicited by T cells deficient in IL-17A correlated with higher expression of genes encoding T helper type 1–type cytokines in colon tissue. IL-17A also modulated T helper type 1 polarization in vitro. Furthermore, T cells deficient in the IL-17 receptor elicited an accelerated, aggressive wasting disease relative to that elicited by wild-type T cells in recipient mice. Our data demonstrate a protective function for IL-17 and identify T cells as not only the source but also a target of IL-17 in vivo. [ABSTRACT FROM AUTHOR]

The outcome of malaria infection is determined, in part, by the balance of pro-inflammatory and regulatory immune responses. Failure to develop an effective pro-inflammatory response can lead to unrestricted parasite replication, whilst failure to regulate this response leads to the development of severe immunopathology. IL-10 and TGF-β are known to be important components of the regulatory response, but the cellular source of these cytokines is still unknown. Here we have examined the role of natural and adaptive regulatory T cells in the control of malaria infection and find that classical CD4+CD25hi (and Foxp3+) regulatory T cells do not significantly influence the outcome of infections with the lethal (17XL) strain of Plasmodium yoelii (PyL). In contrast, we find that adaptive IL-10-producing, CD4+ T cells (which are CD25-, Foxp3-, and CD127- and do not produce Th1, Th2, or Th17 associated cytokines) that are generated during both PyL and non-lethal P. yoelii 17X (PyNL) infections are able to down-regulate pro-inflammatory responses and impede parasite clearance. In summary, we have identified a population of induced Foxp3- regulatory (Tr1) T cells, characterised by production of IL-10 and down regulation of IL-7Rα, that modulates the inflammatory response to malaria. [ABSTRACT FROM AUTHOR]

Regulatory T cells (Treg cells) expressing the transcription factor Foxp3 are key in maintaining the balance of immune homeostasis. However, distinct induced T regulatory type 1 (Tr1) cells that lack Foxp3 expression also regulate T cell function, mainly by producing the immunosuppressive cytokine interleukin 10 (IL-10). However, the factors required for the induction of IL-10-producing suppressive T cells are not fully understood. Here we demonstrate that dendritic cells modified by Treg cells induced the generation of IL-10-producing Tr1 cells. The differentiation of naive CD4+ T cells into IL-10-producing cells was mediated by IL-27 produced by the Treg cell–modified dendritic cells, and transforming growth factor-β amplified the generation of induced IL-10+ Tr1 cells by IL-27. Thus, IL-27 and transforming growth factor-β promote the generation of IL-10-producing Tr1 cells. [ABSTRACT FROM AUTHOR]

It has been known for some time that single mutant nude or CD40T mice have apparently normal numbers of cells in the precursor compartments of bone marrow and the mature B cell compartments of the periphery. X-linked immunodeficiency (XID) mice are deficient only in some of the slgM+slgD+ B cells. We have investigated further the contributions of the xid mutation, of the T cell deficiency of nude and of the inability of CD40T B cells to cooperate with T cells in the generation of the precursor and the mature B cell compartments in mice. Double mutant XIDInu and XIDlCD4OT mice have precursor B cell compartments that are no more deficient than the single mutant XID mice. However, the peripheral B cell compartments of both XIDInu and XIDlCD40T are even more deficient than those of single mutant XID mice. While 10% of the peripheral B cells of wild-type or CD40T, one-third of XID and half of XIDInu mice turn over rapidly, as many as threequarters of those in XIDlCD40T are short-lived. Total numbers of slgM+slgD+ B cells in the spleen are at best 1615% of normal mice at 6-8 weeks of age in XID, XIDInu and XIDICD40T mice. They remain that low at 3 months of age in XIDICD40T mice, while in XID mice these peripheral B cells slowly build up in numbers with age. As expected, double mutant XIDlCD40T mice do not respond to the T-dependent antigen keyhole limpet hemocyanin. Only the responses to the T-independent type I antigen, TNP-lipopolysaccharide (LPS), appear to be normal. In vitro, their splenic B cells respond poorly to LPS or to IgM-specific antibody in either the absence or presence of cytokines. Most notably, serum IgM, lgG2b and lgG3 levels are severely depressed, while IgG1, lgG2a and IgA levels are

IL-10-producing B cells, also known as regulatory B cells (Bregs), play a key role in controlling autoimmunity. In this study, we report that chimeric mice specifically lacking IL-10-producing B cells (IL-10-/-B cell) developed an exacerbated arthritis compared with chimeric wild-type (WT) B cell mice. A significant decrease in the absolute numbers of Foxp3 regulatory T cells (Tregs), in their expression level of Foxp3, and a marked increase in inflammatory Th1 and Th17 cells were detected in IL-10-/- B cell mice compared with WT B cell mice. Reconstitution of arthritic B cell deficient (μMT) mice with different B cell subsets revealed that the ability to modulate Treg frequencies in vivo is exclusively restricted to transitional 2 marginal zone precursor Bregs. Moreover, transfer of WT transitional 2 marginal zone precursor Bregs to arthritic IL-10-/- mice increased Foxp3+ Tregs and reduced Th1 and Th17 cell frequencies to levels measured in arthritic WT mice and inhibited inflammation. In vitro, IL-10+/+ B cells established longer contact times with arthritogenic CD4+CD25- T cells compared with IL-10-/- B cells in response to Ag stimulation, and using the same culture conditions, we observed upregulation of Foxp3 on CD4+ T cells. Thus, IL-10-producing B cells restrain inflammation by promoting differentiation of immunoregulatory over proinflammatory T cells. [ABSTRACT FROM AUTHOR]

Summary: T helper 17 (Th17) cells are important for host defense against extracellular microorganisms. However, they are also implicated in autoimmune and chronic inflammatory diseases, and as such need to be tightly regulated. The mechanisms that directly control committed pathogenic Th17 cells in vivo remain unclear. We showed here that IL-17A-producing CD4+ T cells expressed interleukin-10 receptor α (IL-10Rα) in vivo. Importantly, T cell-specific blockade of IL-10 signaling led to a selective increase of IL-17A+IFN-γ− (Th17) and IL-17A+IFN-γ+ (Th17+Th1) CD4+ T cells during intestinal inflammation in the small intestine. CD4+Foxp3− IL-10-producing (Tr1) cells and CD4+Foxp3+ regulatory (Treg) cells were able to control Th17 and Th17+Th1 cells in an IL-10-dependent manner in vivo. Lastly, IL-10 treatment of mice with established colitis decreased Th17 and Th17+Th1 cell frequencies via direct signaling in T cells. Thus, IL-10 signaling directly suppresses Th17 and Th17+Th1 cells. [Copyright &y& Elsevier]

B cells are exposed to high levels of CD40 ligand (CD40L, CD154) in chronic inflammatory diseases. In addition, B cells expressing both CD40 and CD40L have been identified in human diseases such as autoimmune diseases and lymphoma. However, how such constitutively CD40-activated B cells under inflammation may impact on T cell response remains unknown. Using a mouse model in which B cells express a CD40L transgene (CD40LTg) and receive autocrine CD40/CD40L signaling, we show that CD40LTg B cells stimulated memory-like CD4 and CD8 T cells to express IL-10. This IL-10 expression by CD8 T cells was dependent on IFN-I and programmed cell death protein 1, and was critical for CD8 T cells to counterregulate their overactivation. Furthermore, adoptive transfer of naive CD8 T cells in RAG-1(-/-) mice normally induces colitis in association with IL-17 and IFN-γ cytokine production. Using this model, we show that adoptive cotransfer of CD40LTg B cells, but not wild-type B cells, significantly reduced IL-17 response and regulated colitis in association with IL-10 induction in CD8 T cells. Thus, B cells expressing CD40L can be a therapeutic goal to regulate inflammatory CD8 T cell response by IL-10 induction.

The role of direct IL-10 signaling in different T cell subsets is not well understood. To address this, we generated transgenic mice expressing a dominant-negative IL-10 receptor specifically in T cells (CD4dnIL-10Rα). We found that Foxp3-depleted CD45RB(lo) (regulatory T cell [T(reg) cell]-depleted CD45RB(lo)) but not CD45RB(hi) CD4(+) T cells are controlled directly by IL-10 upon transfer into Rag1 knockout (KO) mice. Furthermore, the colitis induced by transfer of T(reg) cell-depleted CD45RB(lo) CD4(+) T cells into Rag1 KO mice was characterized by reduced Th1 and increased Th17 cytokine messenger RNA levels in the colon as compared with the colitis induced by transfer of CD45RB(hi) T cells. In contrast to the CD45RB(hi) transfer colitis model, in which IL-22 is protective, we found that T cell-derived IL-22 was pathogenic upon transfer of T(reg) cell-depleted CD45RB(lo) T cells into Rag1 KO mice. Our results highlight characteristic differences between colitis induced by naive (CD45RB(hi)) and memory/effector (T(reg) cell-depleted CD45RB(lo)) cells and different ways that IL-22 impacts inflammatory bowel disease.

Introduction: IL-10 is a very important anti-inflammatory cytokine. However, the role of this cytokine in T cells in the pathogenesis of collagen-induced arthritis is unclear. The purpose of this study was to define the role of IL-10 signaling in T cells in the pathogenesis of collagen-induced arthritis., Methods: IL-10 receptor dominant-negative transgenic (Tg) and control mice were immunized with bovine type II collagen to induce arthritis. The severity of arthritis was monitored and examined histologically. T-cell activation and cytokine production were analyzed using flow cytometry. T-cell proliferation was examined by [3H]thymidine incorporation. Antigen-specific antibodies in serum were measured by ELISA. Foxp3 expression in CD4+ regulatory T cells (Tregs) was determined by intracellular staining or Foxp3-RFP reporter mice. The suppressive function of Foxp3+ CD4+ Tregs was determined in vitro by performing a T-cell proliferation assay. The level of IL-17 mRNA in joints was measured by real-time PCR. A two-tailed nonparametric paired test (Wilcoxon signed-rank test) was used to calculate the arthritis and histological scores. Student's paired or unpaired t-test was used for all other statistical analyses (InStat version 2.03 software; GraphPad Software, San Diego, CA, USA)., Results: Blocking IL-10 signaling in T cells rendered mice, especially female mice, highly susceptible to collagen-induced arthritis. T-cell activation and proliferation were enhanced and produced more IFN-γ. The suppressive function of CD4+ Foxp3+ regulatory T cells was significantly impaired in Tg mice because of the reduced ability of Tregs from Tg mice to maintain their levels of Foxp3. This was further confirmed by transferring Foxp3-RFP cells from Tg or wild-type (Wt) mice into a congenic Wt host. The higher level of IL-17 mRNA was detected in inflammatory joints of Tg mice, probably due to the recruitment of IL-17+ γδ T cells into the arthritic joints., Conclusion: IL-10 signaling in T cells is critical for dampening the pathogenesis of collagen-induced arthritis by maintaining the function of Tregs and the recruitment of IL-17+ γδ T cells.

West Nile virus (WNV), a mosquito-borne single-stranded RNA flavivirus, can cause significant human morbidity and mortality. Our data show that interleukin-10 (IL-10) is dramatically elevated both in vitro and in vivo following WNV infection. Consistent with an etiologic role of IL-10 in WNV pathogenesis, we find that WNV infection is markedly diminished in IL-10 deficient (IL-10(-/-)) mice, and pharmacologic blockade of IL-10 signaling by IL-10 neutralizing antibody increases survival of WNV-infected mice. Increased production of antiviral cytokines in IL-10(-/-) mice is associated with more efficient control of WNV infection. Moreover, CD4(+) T cells produce copious amounts of IL-10, and may be an important cellular source of IL-10 during WNV infection in vivo. In conclusion, IL-10 signaling plays a negative role in immunity against WNV infection, and blockade of IL-10 signaling by genetic or pharmacologic means helps to control viral infection, suggesting a novel anti-WNV therapeutic strategy.

The outcome of malaria infection is determined, in part, by the balance of pro-inflammatory and regulatory immune responses. Failure to develop an effective pro-inflammatory response can lead to unrestricted parasite replication, whilst failure to regulate this response leads to the development of severe immunopathology. IL-10 and TGF-beta are known to be important components of the regulatory response, but the cellular source of these cytokines is still unknown. Here we have examined the role of natural and adaptive regulatory T cells in the control of malaria infection and find that classical CD4+CD25(hi) (and Foxp3+) regulatory T cells do not significantly influence the outcome of infections with the lethal (17XL) strain of Plasmodium yoelii (PyL). In contrast, we find that adaptive IL-10-producing, CD4+ T cells (which are CD25-, Foxp3-, and CD127- and do not produce Th1, Th2, or Th17 associated cytokines) that are generated during both PyL and non-lethal P. yoelii 17X (PyNL) infections are able to down-regulate pro-inflammatory responses and impede parasite clearance. In summary, we have identified a population of induced Foxp3- regulatory (Tr1) T cells, characterised by production of IL-10 and down regulation of IL-7Ralpha, that modulates the inflammatory response to malaria.

Although interferon gamma (IFN-gamma) secretion is essential for control of most intracellular pathogens, host survival often also depends on the expression of interleukin 10 (IL-10), a cytokine known to counteract IFN-gamma effector functions. We analyzed the source of regulatory IL-10 in mice infected with the protozoan parasite Toxoplasma gondii. Unexpectedly, IFN-gamma-secreting T-bet(+)Foxp3(-) T helper type 1 (Th1) cells were found to be the major producers of IL-10 in these animals. Further analysis revealed that the same IL-10(+)IFN-gamma(gamma) population displayed potent effector function against the parasite while, paradoxically, also inducing profound suppression of IL-12 production by antigen-presenting cells. Although at any given time point only a fraction of the cells appeared to simultaneously produce IL-10 and IFN-gamma, IL-10 production could be stimulated in IL-10(-)IFN-gamma(+) cells by further activation in vitro. In addition, experiments with T. gondii-specific IL-10(+)IFN-gamma(+) CD4 clones revealed that although IFN-gamma expression is imprinted and triggered with similar kinetics regardless of the state of Th1 cell activation, IL-10 secretion is induced more rapidly from recently activated than from resting cells. These findings indicate that IL-10 production by CD4(+) T lymphocytes need not involve a distinct regulatory Th cell subset but can be generated in Th1 cells as part of the effector response to intracellular pathogens.