Toxoplasma gondii has been shown to result in life-threatening encephalitis in immunocompromised patients after reactivation of dormant parasites. In order to obtain information on immune responses related to this phenomenon, BALB/c mice were infected with 25 cysts of the 76K strain of T. gondii, then, treated orally with dexamethasone (Toxo/Dexa-treated group) in order to reactivate the chronic toxoplasmosis. None of the T. gondii-infected mice died during the experimental periods, whereas the Toxo/Dexa-treated mice evidenced a significant attenuation of survival periods. Toxoplasma-specific IgG2a, IgA and IgM titers in sera were significantly depressed in the Toxo/Dexa-treated mice; however, the IgG1 sera titers were similar to those seen in the Toxoplasma-infected mice. The percentages of CD4+ and CD8 alpha + T cells in the Toxo/Dexa-treated mice were significantly reduced 2 weeks after dexamethasone treatment. IFN-gamma and IL-10 production levels in the Toxo/Dexa-treated mice were depressed significantly, whereas IL-4 production was increased temporarily. The expression levels of the Toxoplasma-specific P30 and B1 genes were found to have been increased in the Toxo/Dexa-treated mice in comparison with the Toxoplasmainfected mice. Collectively, the findings of this study demonstrate that reactivation of murine toxoplasmosis as the result of dexamethasone treatment induced a depression in Th1 immune responses, whereas Th2 immune responses were not significantly influenced.
Toxoplasmosis/*immunology/parasitology ; Toxoplasma/*immunology ; Th2 Cells/immunology ; Th1 Cells/immunology ; Mice, Inbred BALB C ; Mice ; Immunoglobulins/*biosynthesis/immunology ; Female ; Dexamethasone/*pharmacology ; Cytokines/*biosynthesis ; Antibodies, Protozoan/*biosynthesis/immunology ; Animals

Toll-like receptors (TLRs) are pivotal components of the innate immune response, which is responsible for eradicating invading microorganisms through the induction of inflammatory molecules. These receptors are also involved in responding to harmful endogenous molecules and have crucial roles in the activation of the innate immune system and shaping the adaptive immune response. However, TLR signaling pathways must be tightly regulated because undue TLR stimulation may disrupt the fine balance between pro- and anti-inflammatory responses. Such disruptions may harm the host through the development of autoimmune and inflammatory diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Several studies have investigated the regulatory pathways of TLRs that are essential for modulating proinflammatory responses. These studies reported several pathways and molecules that act individually or in combination to regulate immune responses. In this review, we have summarized recent advancements in the elucidation of the negative regulation of TLR signaling. Moreover, this review covers the modulation of TLR signaling at multiple levels, including adaptor complex destabilization, phosphorylation and ubiquitin-mediated degradation of signal proteins, manipulation of other receptors, and transcriptional regulation. Lastly, synthetic inhibitors have also been briefly discussed to highlight negative regulatory approaches in the treatment of inflammatory diseases.
Animals ; Cytokines/biosynthesis ; Humans ; Ligands ; Models, Immunological ; Signal Transduction/*immunology ; Toll-Like Receptors/antagonists & inhibitors/*metabolism

Animals ; Antigens, CD ; immunology ; Cytokines ; metabolism ; Hepacivirus ; immunology ; Hepatitis C ; immunology ; prevention & control ; virology ; Hepatitis C Antibodies ; biosynthesis ; immunology ; Hepatitis C Antigens ; immunology ; Humans ; Killer Cells, Natural ; immunology ; T-Lymphocytes ; immunology ; metabolism ; T-Lymphocytes, Regulatory ; immunology ; metabolism ; Viral Proteins ; immunology

OBJECTIVETo evaluate the effect of early intervention with Mycobacterium phlei F.U.36 injection on the balance of CD4⁺CD25⁺ regulatory T cells and Th17 cells in asthmatic mice, and to investigate the immunomodulatory effect of Mycobacterium phlei F.U.36.

METHODSThirty female BALB/c mice were randomly divided into three groups: normal control (n=10), asthma model (n=10) and Mycobacterium phlei F.U.36 treatment groups (n=10). A mouse model of asthma was prepared by injection and aerosol inhalation of chicken ovalbumin in the asthma model and Mycobacterium phlei F.U.36 treatment groups, while mice in the normal control group were given normal saline instead. The treatment group was intraperitoneally injected with Mycobacterium phlei F.U.36 (0.57 μg, once every other day) three times in the first two weeks after the first sensitization. All mice were sacrificed at 24 hours after the last challenge. Left lung tissues of these mice were obtained and made into sections for observation of inflammatory changes. The percentages of CD4⁺CD25⁺ regulatory T cells and Th17 cells in CD4⁺ T cells among splenic mononuclear cells were determined by flow cytometry. The levels of interleukin (IL)-10 and IL-17 in serum and bronchoalveolar lavage fluid were measured using ELISA.

RESULTSCompared with the normal control group, the asthma model group had significantly decreased percentages of CD4⁺CD25⁺ regulatory T cells and IL-10 levels (P<0.05) and significantly increased percentages of Th17 cells and IL-17 levels (P<0.05). Compared with the asthma model group, the Mycobacterium phlei F.U.36 treatment group had significantly increased percentages of CD4⁺CD25⁺ regulatory T cells and IL-10 levels (P<0.05) and significantly decreased percentage of Th17 cells and IL-17 levels (P<0.05).

CONCLUSIONSEarly intervention with Mycobacterium phlei F.U.36 can promote development of CD4⁺CD25⁺ regulatory T cells and production of IL-10 and inhibit generation of Th17 cells and production of IL-17 in asthmatic mice.

Animals ; Asthma ; immunology ; Cytokines ; biosynthesis ; Female ; Interleukin-10 ; blood ; Interleukin-17 ; blood ; Mice ; Mice, Inbred BALB C ; Mycobacterium phlei ; immunology ; T-Lymphocytes, Regulatory ; immunology ; Th17 Cells ; immunology

The role of alveolar macrophages (AMs) in the pathogenesis of asthma is still unknown. The aim of the present study was to investigate the effects of AM in the murine model of asthma. AMs were selectively depleted by liposomes containing clodronate just before allergen challenges, and changes in inflammatory cells and cytokine concentrations in bronchoalveolar lavage (BAL) fluid were measured. AMs were then adoptively transferred to AM-depleted sensitized mice and changes were measured. Phenotypic changes in AMs were evaluated after in vitro allergen stimulation. AM-depletion after sensitization significantly increased the number of eosinophils and lymphocytes and the concentrations of IL-4, IL-5 and GM-CSF in BAL fluid. These changes were significantly ameliorated only by adoptive transfer of unsensitized AMs, not by sensitized AMs. In addition, in vitro allergen stimulation of AMs resulted in their gaining the ability to produce inflammatory cytokines, such as IL-1beta, IL-6 and TNF-alpha, and losing the ability to suppress GM-CSF concentrations in BAL fluid. These findings suggested that AMs worked probably through GM-CSF-dependent mechanisms, although further confirmatory experiments are needed. Our results indicate that the role of AMs in the context of airway inflammation should be re-examined.
Animals ; Asthma/*immunology ; Bronchoalveolar Lavage Fluid/chemistry/cytology/immunology ; Cytokines/biosynthesis/immunology ; Disease Models, Animal ; Female ; Immunization ; Immunomodulation/*immunology ; Inflammation/*immunology ; Leukocytes/immunology ; Macrophages, Alveolar/*immunology ; Mice ; Mice, Inbred C57BL ; Ovalbumin/immunology

Six recombinant plasmids co-expressing the wild-type GP5 gene or the codon-optimized GP5 gene (containing pan-DR epitope) of porcine reproductive and respiratory syndrome virus (PRRSV) and the E2 gene of classical swine fever virus (CSFV) or the E2 fused with the UL49 of pseudorabies virus (PrV) were constructed based on the suicidal DNA vaccine pSFV1CS-E2 described previously. Expression of GP5 and E2 was confirmed by indirect immunofluorescence assay. The immunogenicity of six plasmids was evaluated in BALB/c mouse model. For the six plasmids, low-level of E2 and GP5 protein specific antibodies could be detected in the sera of the immunized mice. Specific lymphoproliferative responses to the PRRSV or CSFV stimulation were induced in the splenocytes of the immunized mice as demonstrated by CFSE staining assay and WST-8 assay. Antigen specific IFN-gamma and L-4 secretion was detected in the splenocytes of some immunized mice by cytokine ELSIA. Fusion with the PrV UL49 in the suicidal vaccines induced significantly higher lymphoproliferative responses and cytokine secretion. Taken together, the suicidal DNA vaccines co-expressing GP5 and E2 could induce PRRSV and CSFV specific humoral and cell-mediated immune responses.
Animals ; Antibodies, Viral ; blood ; Antibody Formation ; Cytokines ; blood ; Female ; Immunity, Cellular ; Lymphocytes ; immunology ; Mice ; Mice, Inbred BALB C ; Random Allocation ; Vaccines, DNA ; biosynthesis ; immunology ; Viral Envelope Proteins ; genetics ; immunology ; Viral Structural Proteins ; genetics ; immunology ; Viral Vaccines ; biosynthesis ; immunology

Increasing importance is being given to the stimulation of Th1 response in cancer immunotherapy because its presence can shift the direction of adaptive immune responses toward protective immunity. Based on chemokine receptor expression, CXCR3+CCR4-CD4+ T cells as Th1-type cells were investigated its capacity in monocyte-derived dendritic cell (DC) maturation and polarization, and induction of antigen specific cytotoxic T lymphocytes (CTL) in vitro. The levels of IL-4, IL-5 and IL-10 were decreased to the basal level compared with high production of IFN-gamma, TNF-alpha, and IL-2 in CXCR3+CCR4-CD4+ T cells stimulated with anti-CD3 and anti-CD28 antibodies. Co-incubation of activated CD4+ or CXCR3+CCR4-CD4+ T cells with DC (CD4+/DC or CXCR3+CD4+/DC, respectively) particularly up-regulated IL-12 and CD80 expression compared with DC matured with TNF-alpha and LPS (mDC). Although there was no significant difference between the effects of the CXCR3+CCR4-CD4+ and CD4+ T cells on DC phenotype expression, CXCR3+CD4+/DC in CTL culture were able to expand number of CD8+ T cells and increased frequencies of IFN-gamma secreting cells and overall cytolytic activity against tumor antigen WT-1. These results demonstrated that the selective addition of CXCR3+CCR4-CD4+ T cells to CTL cultures could enhance the induction of CTLs by DC in vitro, and implicated on a novel strategy for adoptive T cell therapy.
Antigens, CD4/*immunology ; Cell Line ; Cells, Cultured ; Cytokines/immunology ; Cytotoxicity, Immunologic ; Dendritic Cells/cytology/*immunology ; Humans ; Interferon-gamma/biosynthesis ; Receptors, CCR4/*immunology ; Receptors, CXCR3/*immunology ; T-Lymphocytes, Cytotoxic/*cytology/immunology ; Th1 Cells/*immunology

A large body of evidence demonstrates that dendritic cells (DC) play a pivotal role in the control of immunity by priming and tolerizing T cells. In multiple sclerosis (MS), autoreactive T cells are proposed to play a pathogenic role by secreting pro-inflammatory cytokines, but comparison studies on the effects of immature and mature dendritic cells on the cytokines profile of antigen-specific T cell lines are lacking. To evaluate the actions of dendritic cell maturation on T cell polarization, the effects of immature and mature dendritic cells derived from MS patients on in vitro proliferative responses, and cytokine production by glatiramer acetate (GA)- specific T cell lines (TCL) derived from MS patients were analyzed. The results demonstrated that it is easy to derive GA-specific TCL from MS patients with high specificity; lipopolysaccharide can efficiently induce DC maturation within 24 hours at a concentration of 5 micro g/ml; mature DC showed higher co-stimulatory capacity of GA-specific TCLs than immature DC. GA-specific TCLs produce dominantly IL-2, IL-4, IFN-gamma and IL-10, but low levels of IL-6. In contrast to immature DC, mature DC enhanced capacity to induce IL-6 and IL-10 secretion, but down-regulate IL-2, IL-4 and IFN-gamma production by GA- specific TCLs. It is concluded that DC maturation status modulating proliferation of TCL and production of cytokines may represent another focus for the study on both immuno-pathogenesis and immunotherapeutic interventions in MS.
Adult ; Cell Line ; Cytokines ; biosynthesis ; Dendritic Cells ; physiology ; Female ; Glatiramer Acetate ; Humans ; Lymphocyte Activation ; Male ; Middle Aged ; Multiple Sclerosis ; immunology ; Peptides ; immunology ; T-Lymphocytes ; immunology

OBJECTIVESevere pneumonia is one of the common severe diseases in children. Increasing evidences show that immune response greatly contribute to severe pneumonia. Dendritic cells (DC) are the important antigen presenting cells in the lung. To study the role of dendritic cells in development of severe pneumonia in children, the authors measured the number of mature DC in bronchoalveolar lavage fluid (BALF), and evaluated the relationship among IL-12, pro-inflammatory cytokines and clinical scores.

METHODSThe following 3 groups of children were enrolled in this study: severe pneumonia group: 27 children with severe pneumonia treated between November 2002 and May 2003 in PICU; mild pneumonia group: 30 children with mild pneumonia in department of pulmonology; control group: 29 children without pneumonia but receiving ventilator treatment for chest surgery. Mature DC in BALF was determined in severe pneumonia group and the control group on the day of tracheal intubation for mechanical ventilation. Acute lung injury scores and severe disease scores were evaluated in children with severe pneumonia and mild pneumonia. All children's serum levels of TNF-alpha, IL-6 and IL-12 were measured by using ELISA within 24 hours after admission. SPSS version 11.5 was used for statistical analysis.

RESULTS(1) The percent of mature DC in children with severe pneumonia was significantly higher when compared with the control group on the first day after ventilation [14.2 (3.9 - 51.8)] vs. [1.3 (0.2 - 22.5)] (Z = 5.44, P < 0.01). (2) In severe pneumonia group, the concentration of serum IL-12 [117.0 (79.9 - 159.4) ng/L], TNF-alpha [90.6 (52.2 - 185.9) ng/L], IL-6 [128.7 (73.3 - 793.8) ng/L] were significantly higher than those in mild pneumonia group where the values were [71.6 (19.4 - 196.8)], [26.6 (2.5 - 113.9)], and [39.9 (7.8 - 82.5)] (P < 0.01), and the control group [6.4 (12.2 - 92.0)], [6.4 (1.8 - 91.9)], and [23.0 (6.4 - 54.2)] (P < 0.01). Serum IL-12, TNF-alpha and IL-6 levels in children with mild pneumonia were higher than those of control group (P < 0.01). (3) The percent of mature DC was increased with the serum level of IL-12 (r = 0.48, P < 0.01), TNF-alpha (r = 0.58, P < 0.01), IL-6 (r = 0.51, P < 0.01) and lung injury scores (r = 0.39, P < 0.05), but it did not correlate with severe disease scores (r = -0.11, P > 0.05).

CONCLUSIONSThere is excessive production of pro-inflammatory cytokines and over-stimulation of lung dendritic cells in children with severe pneumonia. Over-stimulation of lung dendritic cells, the increased serum levels of IL-12, TNF-alpha, IL-6 and the severity of pneumonia may suggest that DC plays an important role in pathogenesis of severe pneumonia in children.

Bronchoalveolar Lavage Fluid ; cytology ; Child, Preschool ; Cytokines ; biosynthesis ; blood ; Dendritic Cells ; immunology ; Enzyme-Linked Immunosorbent Assay ; Female ; Humans ; Infant ; Interleukin-12 ; biosynthesis ; Interleukin-6 ; biosynthesis ; Male ; Pneumonia ; immunology ; pathology ; physiopathology ; Severity of Illness Index ; Tumor Necrosis Factor-alpha ; biosynthesis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by persistent joint swelling and progressive destruction of cartilage and bone. Current RA treatments are largely empirical in origin and their precise mechanism of action is uncertain. Increasing evidence shows that chronic inflammatory diseases such as RA are caused by prolonged production of proinflammatory cytokines including tumor necrosis factor (TNF) and interleukin 1 (IL-1). The nuclear factor kappaB (NF-kappaB) plays an essential role in transcriptional activation of TNF and IL-1. NF-kappaB is induced by many stimuli including TNF and IL-1, forming a positive regulatory cycle that may amplify and maintain RA disease process. NF-kappaB and enzymes involved in its activation can be a target for anti-inflammatory treatment. Aspirin and sodium salicylate inhibit activation of NF-KB by blocking IkappaB kinase, a key enzyme in NF-kappaB activation. Glucocorticoids suppress expression of inflammatory genes by binding glucocorticoid receptor with NF-kappaB, and increasing expression of inhibitory protein of NF-kappaB, IkappaBalpha. Sulfasalazine and gold compounds also inhibit NF-kappaB activation. Continuing advances in our understanding of action mechanism of antirheumatic agents will benefit the future development of RA regimens with greater efficacy and less toxicity.
Animal ; Antirheumatic Agents/therapeutic use* ; Arthritis, Rheumatoid/therapy* ; Arthritis, Rheumatoid/metabolism ; Arthritis, Rheumatoid/immunology ; Cytokines/immunology ; Cytokines/genetics ; Gene Expression Regulation ; Human ; Macrophages/immunology ; NF-kappa B/metabolism* ; NF-kappa B/immunology ; NF-kappa B/biosynthesis ; Tumor Necrosis Factor/genetics