Programmed cell death-1 expression correlates with disease severity and IL-5 in chronic rhinosinusitis with nasal polyps.

BACKGROUND: Programmed cell death-1 (PD-1) is a negative regulator of T-cell responses. Expression of PD-1 and its ligands PD-L1 and PD-L2 in chronic rhinosinusitis with nasal polyps (CRSwNP) is poorly studied. METHODS: Expression of PD-1, PD-L1, PD-L2, TGF-ß, IL-5, and IL-10 mRNA was measured by real-time quantitative PCR on tissue homogenates of patients with CRSwNP (n = 21) and healthy controls (n = 21) and on primary epithelial cells. Disease severity was scored using the Lund-Mackay scores of maxillofacial computed tomography (CT) scans. Expression of PD-1 and PD-L1/L2 was evaluated at the cellular and tissue levels (n = 6) by flow cytometry and immunohistochemistry. RESULTS: Programmed cell death-1 mRNA expression was increased in tissue homogenates from patients with CRSwNP compared with controls, irrespective of the atopy status. Importantly, expression of PD-1 correlated with the total CT scan scores (r = 0.5, P = 0.02). Additionally, a significant association was found between PD-1 mRNA and expression of IL-5 mRNA in control nasal tissue (r = 0.95, P < 0.0001) and in CRSwNP (r = 0.63, P = 0.002). PD-1 was expressed on different subsets of T cells and CD11b- dendritic cells. Both PD-1 and its ligands were expressed on primary epithelial cells from control nasal tissue and nasal polyp tissue. CONCLUSIONS: Higher PD-1 expression was found in CRSwNP than in nasal tissue from controls. This was associated with disease severity and tissue IL-5 expression but unrelated to the patients' atopy status.

A chest physician's guide to mechanisms of sinonasal disease.

The upper and lower airways are closely linked from an anatomical, histological and immunological point of view, with inflammation in one part of the airways influencing the other part. Despite the concept of global airway disease, the upper airways tend to be overlooked by respiratory physicians. We provide a clinical overview of the most important and recent insights in rhinitis and rhinosinusitis in relation to lower airway disease. We focus on the various exogenous and endogenous factors that play a role in the development and aggravation of chronic upper airway inflammation. In addition to the classical inhaled allergens or microorganisms with well-defined pathophysiological mechanisms in upper airway disease, environmental substances such as cigarette smoke, diesel exhaust particles and occupational agents affecting lower airway homeostasis have recently gained attention in upper airway research. We are only at the beginning of understanding the complex interplay between exogenous and endogenous factors like genetic, immunological and hormonal influences on chronic upper airway inflammation. From a clinical perspective, the involvement of upper and lower airway disease in one patient can only be fully appreciated by doctors capable of understanding the interplay between upper and lower airway inflammation.

Vascular endothelial growth factor receptor 1 expression in nasal polyp tissue.

BACKGROUND: Edema represents a key feature of nasal polyp (NP) disease. Members of the vascular endothelial growth factor (VEGF) family may be involved, but the precise role of VEGF-A, VEGF-B, placental growth factor (PlGF), and their receptors VEGFR1 and VEGFR2 in NP edema formation remains elusive. OBJECTIVE: Exploring the expression of VEGF family members and their receptors and their correlation with clinical, radiological, and edema markers in NP. METHODS: The expression of VEGF-A, VEGF-B, PlGF, VEGFR1, and VEGFR2 was measured in NP (n = 23) and control tissue (n = 22) at mRNA and protein level. Edema was evaluated by measuring albumin levels and wet/dry ratios. Computed tomography (CT) scans were scored using the Lund-Mackay scoring system. IL-5 mRNA expression was determined by real-time RT-PCR. Cell suspensions from NP (n = 10) and control tissue (n = 12) were stimulated in vitro with IL-1ß or TNFα. RESULTS: mRNA expression of VEGFR1 and VEGF-B was significantly higher in NP compared with control tissue. Expression levels of VEGF-B and VEGFR1 significantly correlated with NP albumin content (VEGF-B: P = 0.0208; VEGFR1: P = 0.0293), CT scan scores (VEGF-B: P = 0.0075; VEGFR1: P = 0.0068), and IL-5 mRNA (VEGF-B: P = 0.0027; VEGFR1: P = 0.0001). In vitro stimulation of control and NP tissue cell suspensions with IL-1ß or TNFα significantly reduced the expression of VEGFR2 in control tissue, without altering VEGFR1 and VEGF-B expression. hVEGF-B induced nitric oxide production in NP macrophages (P < 0.05). CONCLUSION: Expression levels of VEGFR1 and VEGF-B correlate with edema and clinical markers of NP disease and therefore represent potential therapeutic targets.

Effects of haptoglobin polymorphisms and deficiency on susceptibility to inflammatory bowel disease and on severity of murine colitis.

BACKGROUND: Haptoglobin (Hp) is a haemoglobin-binding protein with immunomodulatory properties. Its gene (16q22) harbours a common polymorphism with two different alleles: Hp1 and Hp2. Genotype Hp22 has been shown to be over-represented in different immune diseases. Results in Crohn's disease (CD) are contradictory. AIMS: To determine whether Hp plays a role in inflammatory bowel disease, both genetically and functionally. METHODS: 1061 patients with CD, 755 with ulcerative colitis (UC) and 152 with primary sclerosing cholangitis, as well as 452 healthy controls, were genotyped using touch-down PCR. To confirm association results, 464 CD trios and 151 UC trios were genotyped. Serum Hp concentrations were determined in 62 individuals of different genotype. Colitis was induced in mice with dextran sulphate sodium (DSS) and oxazolone (Oxa). Cytokine production was evaluated by mRNA quantification in colonic tissue and ELISA on supernatants of mesenteric lymph node cells. RESULTS: Prevalence of Hp2 was higher in CD and UC than in controls. In the confirmatory cohorts, Hp2 was over-transmitted to the affected offspring. Serum Hp concentrations were higher in individuals with genotypes Hp11 and Hp21 than in those with Hp22 (1.38 vs 0.89 g/l). DSS- and Oxa-induced colitis were more severe in Hp-deficient mice than in control mice and accompanied by higher concentrations (although not statistically significantly different) of tissue mRNA for cytokines. Interleukin-17 production was significantly higher in the presence of Hp-deficient serum compared with wild-type serum. CONCLUSIONS: The Hp gene may play a role in susceptibility to inflammatory bowel disease. Its implication in other immune diseases underscores the common pathways between these diseases. Experimental models of colitis showed that Hp has a protective role in inflammatory colitis, most likely by inhibiting the production of Th1 and Th17 cytokines.

Staphylococcus aureus enterotoxin B augments granulocyte migration and survival via airway epithelial cell activation.

BACKGROUND: Staphylococcus aureus enterotoxin B (SEB) has recently been postulated to be involved in the pathology of granulocyte-dominated disease. Studying the immunologic interaction between SEB and airway epithelial cells in immortalized cell lines or long-term epithelial cell cultures has obvious disadvantages. METHODS: We used a novel technique of freshly isolated and purified human nasal epithelial cells (HNEC) from healthy, nonallergic individuals, which were incubated for 24 h without/with SEB at different concentrations. Chemokine production was evaluated in the supernatant using Cytometric Bead Array. The chemotactic activity of the supernatant was studied in vitro using a Boyden chamber. Survival was evaluated with flow cytometry, using propidium iodide to identify dead cells. RESULTS: Staphylococcus aureus enterotoxin B showed a dose-dependent induction of interferon-inducible protein-10, monokine induced by interferon-gamma, regulated upon activation normal T cell expressed and secreted, monocyte chemoattractant protein 1 (MCP-1) and granulocyte colony stimulating factor production by epithelial cells in vitro. The supernatant of epithelial cells had chemotactic activity for granulocytes in vitro, which was enhanced in the supernatant of SEB-stimulated epithelial cells. Reduced number of propidium iodide positive granulocytes was found in the conditions where supernatant of SEB-stimulated epithelial cells was applied. CONCLUSION: Staphylococcus aureus enterotoxin B exerts a direct pro-inflammatory effect on HNEC, with induction of chemokine and growth factor release, resulting in the migration and prolonged survival of granulocytes in vitro.

Immune dysfunction in patients with functional gastrointestinal disorders.

There is increasing evidence for involvement of the immune system in functional gastrointestinal disorder (FGID), including onset after acute gastrointestinal infections, genotypes resulting in altered cytokine expression and abnormal presence of immune cells. Our aim was to assess cellular and humoral immune responses in (i) FGIDs, compared to healthy subjects and (ii) acute vs unspecified onset FGIDs. Lymphocytic [interleukin (IL)-5, IL-10, IL-13 and interferon gamma (IFN-gamma)] and monocytic [IL-10, IL-12, tumour necrosis factor (TNF)-alpha] cytokine production was characterized at baseline and after stimulation with phytohemagglutinine and anti-CD28 or lipopolysaccharide (LPS) in controls (n = 32), irritable bowel syndrome (IBS) (n = 30), functional dyspepsia (FD) (n = 23) and non-cardiac chest pain (NCCP) (n = 15). Serum IL-6 and IL-10 concentrations were compared, and the immunophenotype was assessed using fluorescent-activated cell sorter. Findings were compared for acute vs unspecified onset FGID. Compared to controls, stimulated lymphocyte expression of IL-5 and IL-13 was enhanced in IBS, FD and NCCP (all P < 0.05). Conversely, the stimulated monocytic IL-12 and lymphocytic IL-10 expression were reduced in IBS and FD, while IFN-gamma expression was also reduced in FD patients. Except for an increase in the numbers of CD3(+)CD45RA(+)CD45RO(+) cells, no distinct cellular profile was detected. Patients with a presumed acute onset of their symptoms had higher serum IL-10 levels and more CD3(+)CD45RA(+)CD45RO(+) cells, while TNF-alpha levels following stimulation with LPS were higher in FD patients reporting an acute onset. A shift towards a Th2 cytokine profile is present in FGID, while the cellular immunophenotype remains largely unchanged. Further research is indicated and could provide new therapeutic strategies for these disorders.

Immunotherapy with a modified birch pollen extract in allergic rhinoconjunctivitis: clinical and immunological effects.

BACKGROUND: Modification of allergens by glutaraldehyde in extracts used for immunotherapy reduces the risk for side-effects, but the therapeutic efficacy of such extracts still requires further evaluation. The aim of this study was to show the efficacy and safety of immunotherapy with a single-strength glutaraldehyde-modified aluminium hydroxide-adsorbed extract of birch pollen. METHODS: In a multi-centre, randomized, placebo-controlled double-blind setting, starting in 2001 between 1 August and 15 December, birch pollen-allergic subjects (n=62) were injected subcutaneously with increasing doses of the allergen extract or placebo at weekly intervals over a 6-week period (or longer if adverse reactions occurred). Maintenance dose was given monthly for at least 18 months till June 2003. Efficacy was evaluated on the basis of the clinical index score (CIS), a combined symptom and medication score. RESULTS: Fifty-eight patients could be evaluated for clinical efficacy. Treatment with the birch pollen extract resulted in a lower CIS for the eye and nose during the peak birch pollen season of 2003, compared with placebo (reductions of 42% and 31%, respectively) (P=0.017 and 0.039). Active treatment induced IgG and IgG4 antibodies reacting with Bet v 1 (P<0.001). Sera from treated patients had a blocking effect on Bet v 1-induced basophil activation (P<0.04). No major adverse reactions occurred, and local reactions, if occurring, were mild. CONCLUSION: Immunotherapy with a modified slow-release birch pollen extract, administered in a single-strength preparation with a rapid dose increase, is safe and efficacious. IgG and IgG4 antibodies against native Bet v 1 are induced, which block basophil activation.

Sinonasal pathology in nonallergic asthma and COPD: 'united airway disease' beyond the scope of allergy.

BACKGROUND: In contrast to the epidemiological and clinical association between allergic rhinitis and asthma, upper airway inflammation is less characterized in patients with nonatopic asthma and virtually unexplored in chronic obstructive pulmonary disease (COPD). Here, sinonasal pathology is studied in patients with allergic asthma, nonallergic asthma and COPD. METHODS: Ninety patients with stable bronchial disease were included in the study, of which 35 were diagnosed with allergic asthma, 24 with nonallergic asthma and 31 with COPD. Concurrently, 61 control subjects without pulmonary disease were included and matched for age and smoking habits respectively with the asthma and the COPD group. Sinonasal symptoms were evaluated on a visual analogue scale and rhinosinusitis-related impairment of quality of life was assessed with the sino-nasal outcome test-22 (SNOT-22) questionnaire. Nasal mucosal abnormalities were quantified with nasal endoscopy and nasal secretions collected for measuring inflammatory mediators. RESULTS: Allergic asthmatics, nonallergic asthmatics and COPD patients reported more nasal symptoms than their respective control subjects, had a higher SNOT-22 score and presented more mucosal abnormalities in the nose. Nasal secretions of both allergic and nonallergic asthmatics contained higher levels of eotaxin, G-CSF, IFN-gamma and MCP-1 than controls. Allergic asthmatics had higher nasal IP-10 levels as well. COPD-patients had higher nasal levels of eotaxin, G-CSF and IFN-gamma than controls. CONCLUSION: Patients with allergic and nonallergic asthma and COPD show increased nasal symptoms and more nasal inflammation. Hence, our data confirm the 'united airways' concept to be beyond the scope of allergic asthma.

Involvement of 4-1BB (CD137)-4-1BBligand interaction in the modulation of CD4 T cell-mediated inflammatory colitis.

4-1BB ligand (4-1BBL) expressed on antigen-presenting cells interacts with 4-1BB on activated T cells (especially CD8+ cells) and co-stimulates the latter to secrete cytokines and to proliferate. The role of 4-1BB-4-1BBL interaction was studied here in a model of colitis based on naive CD4+ T cell transfer to SCID mice, a disease model in which CD8 cells do not take part. We found that CD4+ T cells from 4-1BB-deficient mice, after transfer in SCID mice, proliferated more rapidly compared to wild-type CD4+ T cells. Mice reconstituted with naive CD4+ T cells from 4-1BB-deficient mice developed colitis, however, with a mixed Th1/Th2 response, in contrast to the Th1-type response in mice reconstituted with wild-type naive CD4+ T cells. Importantly, this altered cytokine response did not temper colitis severity. Although it has been reported previously that 4-1BB co-stimulation may contribute to regulatory T cell functioning, we found that CD4+CD25+ regulatory T cells from 4-1BB-deficient mice were perfectly able to prevent naive CD4+ T cell-induced colitis. In conclusion, our data provide evidence that 4-1BB-4-1BBL interaction modulates the effector CD4+ T cell-driven immune response and cytokine production in experimental colitis without affecting regulatory T cell function.

Safety and tolerability of antagonist anti-human CD40 Mab ch5D12 in patients with moderate to severe Crohn's disease.

BACKGROUND: The ligation of CD40 by CD154 is a critical step in the interaction between APC and T cells. In animals, antagonizing CD40L-CD40 has been shown to reduce the severity of several autoimmune and inflammatory disorders, including experimental colitis. AIM: To investigate tolerability and safety of an antagonist chimeric monoclonal anti-human CD40 antibody (ch5D12) for treatment of Crohn's disease. METHOD: ch5D12 was administrated to 18 patients with moderate to severe Crohn's disease in a single dose, open-label dose-escalation phase I/IIa study. RESULTS: ch5D12 plasma concentrations increased dose-dependently after infusion. Two patients developed an anti-ch5D12 antibody response. Overall response and remission rates were 72 and 22%, respectively with no evidence for a dose-response effect. Treatment with ch5D12 reduced microscopic disease activity and intensity of the lamina propria cell infiltrate, but did not alter percentages of circulating T and B cells. ch5D12 was well tolerated, although some patients experienced headache, muscle aches, or joint pains, which may have been related to the study drug. CONCLUSIONS: Antagonizing CD154-CD40 interactions with ch5D12 is a promising therapeutic approach for remission induction in Crohn's disease.

Adalimumab induces apoptosis of human monocytes: a comparative study with infliximab and etanercept.

BACKGROUND: Adalimumab, a fully human monoclonal antibody to tumour necrosis factor, was recently introduced for therapy of Crohn's disease. AIM: Since induction of apoptosis of inflammatory cells is thought to be an important mechanism of action of the antitumour necrosis factor monoclonal antibody infliximab, we studied the induction of apoptosis of activated peripheral blood monocytes by adalimumab. METHOD: Apoptosis was analysed at the levels of the cell membrane, mitochondria and DNA by flow cytometry. RESULTS: We found that both adalimumab and infliximab induced apoptosis in cultured monocytes, while etanercept did not. Apoptosis induction was caspase-dependent and detectable already after 2 h. The production of interleukin-10 and interleukin-12 by monocytes was down-regulated significantly by adalimumab and infliximab but not by etanercept, while levels of soluble tumour necrosis factor in monocyte cultures were down-regulated by all three reagents. CONCLUSIONS: These data show that both adalimumab and infliximab affect monocyte cytokine production and induce apoptosis of activated monocytes. Our findings will have to be further correlated to therapeutic efficacy of these antitumour necrosis factor reagents.

The circulating lymphocyte profiles in patients with discoid lupus erythematosus and systemic lupus erythematosus suggest a pathogenetic relationship.

BACKGROUND: Discoid lupus erythematosus (DLE) and systemic lupus erythematosus (SLE) are chronic inflammatory diseases of unknown aetiology; the relationship of DLE with SLE has been a subject of debate for many years. OBJECTIVES; To find evidence for systemic immune activation in DLE by analysis of the immunophenotypic profiles of circulating lymphocytes, and to compare these changes with those in patients with SLE. METHODS: The immunophenotypic profile of peripheral blood lymphocyte subsets from 23 DLE patients without clinical or laboratory evidence of systemic disease, 25 SLE patients and 38 healthy donors was characterized by two-colour immunofluorescence flow cytometry analysis. None of the patients was receiving corticosteroid or immunosuppressive treatment. RESULTS: Patients with DLE had increased numbers of circulating HLA-DR+ CD3+ T cells and HLA-DR+ CD4+ T cells, indicating systemic T-cell activation, and an expansion of CD5+ CD19+ B cells. Decreased numbers of T-cell subsets expressing the differentiation markers CD11b and CD16/56, and of CD16/56+ natural killer cells were also found. In SLE, the changes were similar but more pronounced. In addition, a profound CD4+ T-cell lymphopenia and an increase of HLA-DR+ CD8+ T cells were found only in SLE. CONCLUSIONS: Our data provide evidence for systemic activation of the cellular immune system in patients with purely cutaneous DLE. Similarities in the lymphocyte immunophenotypic profiles in patients with DLE compared with SLE suggest that there are common immunopathological processes in these two conditions.

Inhibition of costimulation allows for repeated systemic administration of adenoviral vector in rhesus monkeys.

Immunogenicity of recombinant adenoviral (Ad) vectors severely hampers the clinical development of gene therapy protocols using repeated vector administrations. Inhibition of costimulation by APCs was explored as a strategy to circumvent the immune response against Ad particles. This strategy was tested in rhesus monkeys, treated transiently with chimeric anti-human CD40 and anti-human CD86 antagonist monoclonal antibodies (MAbs) at the time of systemic administration of a recombinant Ad vector. After Ad vector administration in the absence of immunosuppressive treatment, transgene expression in the serum lasted about 3-4 weeks. All control animals developed a strong neutralizing antibody (NAb) response to the Ad particles, which totally prevented efficient administration of a second vector, as shown by the lack of transgene expression. Treatment with anti-CD40 and anti-CD86 chimeric MAbs delayed or blocked the development of a humoral response against Ad and the infiltration of CD8(+) lymphocytes into the liver. This resulted in (i) increased persistence of Ad-transduced cells after injection of a first vector encoding a nonimmunogenic transgene, and (ii) the possibility of readministering a second Ad vector with significant efficacy. In both respects, the combined blockade of CD40 and CD86 was more efficient than treatment with anti-CD40 alone. This study shows for the first time in non-human primates that blocking CD40 and CD86 costimulatory molecules represents a promising strategy to inhibit immune responses against an Ad vector injected systemically.

Blocking B7 and CD40 co-stimulatory molecules decreases antiviral T cell activity.

Inhibition of co-stimulatory signals for T cells by interrupting CD80/CD86-CD28 and CD40-CD154 interactions is a promising approach to prevent transplant rejection and to induce graft tolerance. However, this tolerizing treatment might affect T cell reactivity towards all the antigens to which the immune system is exposed during treatment. We addressed the question whether such inhibition of co-stimulatory ligands on human antigen presenting cells (APC) would affect T cell reactivity against a virus. This was tested in an in vitro system with freshly isolated human monocytes transduced with adenovirus (ad) containing either murine interferon-gamma (mIFN-gamma) or green fluorescent protein (GFP) as marker transgene. T cells co-cultured with transduced monocytes proliferated and produced cytokines. These 'primed' T cells had strong antiviral activity as they subsequently killed ad/GFP-transduced monocytes and reduced mIFN-gamma accumulation in coculture with ad/mIFN-transduced monocytes. However, if priming had occurred in the presence of blocking anti-CD40/CD80/CD86 MoAbs, generation of this antiviral activity was completely prevented. Moreover, T cells primed in the absence of co-stimulatory cells failed to proliferate upon restimulation with adenovirus-transduced monocytes. The results confirm that co-stimulatory signals from APC are required for efficient induction of antiviral T cell activity and point to a potential infectious risk of blocking co-stimulatory signals.

Involvement of interleukin 18 in Crohn's disease: evidence from in vitro analysis of human gut inflammatory cells and from experimental colitis models.

An imbalance of immunoregulatory factors and/or cells contributes to uncontrolled mucosal T cell activation and inflammation in Crohn's disease (CD). Bioactive interleukin (IL)-18 has been shown to be produced by macrophages in CD lesions. We report here that T cells freshly isolated from inflamed tissue of CD patients (and not T cells from control intestinal tissue) were responsive to IL-18. In the presence of IL-18, these T cells produced more interferon (IFN)-gamma and less IL-10. To analyse further the role of IL-18 in this disease, an acute and a chronic model of murine colitis were used. IL-18 mRNA was significantly enhanced in trinitrobenzene sulphonic acid (TNBS) induced colitis, and treatment with IL-18 binding protein (IL-18BPa), which neutralizes IL-18 bioactivity, significantly reduced the severity of colitis. However, IL-18BPa did not affect the course of chronic colitis in CD45RBhighCD4+ T cell reconstituted SCID mice. Production of IFN-gamma in lamina propria mononuclear cell cultures from IL-18BPa-treated SCID mice was decreased, but at the same time fewer lamina propria CD4+ T cells harvested from IL-18BPa-treated mice compared to non-treated mice were in apoptosis. We conclude that IL-18 clearly has a modulatory role in the inflammatory cascade of CD and experimental colitis by affecting IFN-gamma and IL-10 production, and apoptosis. In view of the divergent effects of IL-18 neutralization in the two different murine colitis models, it is unlikely that IL-18 is at the top of this cascade.

Progesterone increases airway eosinophilia and hyper-responsiveness in a murine model of allergic asthma.

BACKGROUND: Sex hormones might affect the severity and evolution of bronchial asthma. From existing literature, there exists, however, no convincing evidence for either exacerbation or improvement of allergic symptoms by progesterone. OBJECTIVE: This study was aimed to explore the effect of exogenously administered progesterone in a mouse model of allergic asthma. METHODS: BALB/c mice were sensitized to ovalbumin (OVA) by intraperitoneal injections with OVA followed by chronic inhalation of nebulized OVA or physiologic saline (Sal). Medroxyprogesterone acetate or placebo was instilled daily into the oesophagus before and during the inhalatory OVA challenge phase. RESULTS: Progesterone worsened allergic airway inflammation in OVA-challenged mice, as evidenced by enhanced bronchial responsiveness to inhaled metacholine and increased bronchial eosinophilia. Elevated airway eosinophilia corresponded with higher bronchial and systemic IL-5 levels in the progesterone group. The ratio of IL-4/IFN-gamma levels in bronchoalveolar lavage fluid and numbers of eosinophil colony-forming units in the bone marrow were also elevated in the latter group. Progesterone, however, did not influence allergen-specific IgE production, nor did it affect bronchial responses in Sal-challenged mice. CONCLUSION: Our data show that exogenously administered progesterone aggravates the phenotype of eosinophilic airway inflammation in mice by enhancing systemic IL-5 production. Progesterone also increases bronchial hyper-reactivity.

Haptoglobin directly affects T cells and suppresses T helper cell type 2 cytokine release.

T helper cell type 1 (Th1) and type 2 (Th2) immune responses are characterized by a different pattern of cytokine expression following T-cell activation. Alterations of the ratio of Th1 to Th2 cells are important determinants of susceptibility to viral and parasitic infections, allergies, anti-tumour responses, and autoimmunity. In this work we bring new evidence for an effect of haptoglobin (Hp), a positive acute-phase protein, on T-lymphocyte functions. We show that Hp specifically interacts with both resting and activated CD4+ and CD8+ T cells. This specific binding results in a strong suppression of induced T-cell proliferation. In addition, Hp exhibits a strong in vitro inhibitory effect on Th2 cytokine release, while the production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) is only slightly inhibited at high Hp doses. As a result, the presence of Hp promotes Th1 activation over Th2 activation in vivo as evidenced in Hp-deficient mice. Anti-CD3 monoclonal antibody injection indeed resulted in predominant IL-4 production in Hp-/- mice, in contrast to predominant IFN-gamma production in Hp+/+ mice. We conclude that Hp plays a modulating role on the Th1/Th2 balance by promoting a dominant Th1 cellular response. This points to a role of acute-phase proteins in balancing immune responses.

Effects of anti-tumour necrosis factor, interleukin-10 and antibiotic therapy in the indometacin-induced bowel inflammation rat model.

BACKGROUND: The administration of indometacin to rats increases intestinal permeability and induces inflammatory pathology of the small bowel. This represents a potential model for Crohn's disease. AIMS: To analyse the pathogenic role of T cells, tumour necrosis factor and bacterial flora in indometacin-induced changes in small bowel permeability and inflammation. METHODS: Rats were given indometacin, 13 mg/kg, on day 1 and day 2. The effects of antibiotic (metronidazole, aztreonam and amoxicillin/clavulanic acid), anti- tumour necrosis factor and interleukin-10 therapy were evaluated. The parameters used were weight change, serum haemoglobin, chromium-51 ethylenediaminetetra-acetate permeability and macro-and microscopic score on day 5. Results in conventionally harboured rats were compared with those in T-cell-free rats. Additional in vitro experiments were carried out to test the effect of metronidazole on tumour necrosis factor production. RESULTS: Indometacin administration resulted in small bowel ulcers and inflammation, independently of T cells. Metronidazole was more potent than amoxicillin/clavulanic acid and anti-tumour necrosis factor in improving the indometacin-induced small bowel inflammation. Only part of the efficacy was through improvement of increased intestinal permeability. Aztreonam and interleukin-10 had no effect. Metronidazole also suppressed in vitro lipopolysaccharide-induced tumour necrosis factor production, suggesting a therapeutic effect of this drug through the inhibition of tumour necrosis factor. CONCLUSIONS: These data implicate anaerobic bacteria and tumour necrosis factor production, but not T cells, as essential elements of the pathogenesis of indometacin-induced small bowel inflammation. Tumour necrosis factor is also involved in the change in intestinal permeability. Metronidazole was the most efficacious drug in this model, probably because it suppressed anaerobic bacteria and directly inhibited tumour necrosis factor production.

B7 interactions with CD28 and CTLA-4 control tolerance or induction of mucosal inflammation in chronic experimental colitis.

CD28-B7 interaction plays a critical costimulatory role in inducing T cell activation, while CTLA-4-B7 interaction provides a negative signal that is essential in immune homeostasis. Transfer of CD45RB(high)CD4(+) T cells from syngeneic mice induces transmural colon inflammation in SCID recipients. This adoptive transfer model was used to investigate the contribution of B7-CD28/CTLA-4 interactions to the control of intestinal inflammation. CD45RB(high)CD4(+) cells from CD28(-/-) mice failed to induce mucosal inflammation in SCID recipients. Administration of anti-B7.1 (but not anti-B7.2) after transfer of wild-type CD45RB(high)CD4(+) cells also prevented wasting disease with colitis, abrogated leukocyte infiltration, and reduced production of proinflammatory cytokines IL-2 and IFN-gamma by lamina propria CD4(+) cells. In contrast, anti-CTLA-4 treatment led to deterioration of disease, to more severe inflammation, and to enhanced production of proinflammatory cytokines. Of note, CD25(+)CD4(+) cells from CD28(-/-) mice similar to those from the wild-type mice were efficient to prevent intestinal mucosal inflammation induced by the wild-type CD45RB(high) cells. The inhibitory functions of these regulatory T cells were effectively blocked by anti-CTLA-4. These data show that the B7-CD28 costimulatory pathway is required for induction of effector T cells and for intestinal mucosal inflammation, while the regulatory T cells function in a CD28-independent way. CTLA-4 signaling plays a key role in maintaining mucosal lymphocyte tolerance, most likely by activating the regulatory T cells.