Prospective assessment of serum periostin as a biomarker for diagnosis and monitoring of eosinophilic oesophagitis.

BACKGROUND: Periostin is highly expressed in eosinophilic oesophagitis (EoE), but has not been extensively studied as a non-invasive biomarker. AIM: To assess whether serum periostin distinguished EoE from controls at baseline, had utility for monitoring treatment response, or was associated with IL-13 levels. METHODS: This was a sub-analysis of a prospective cohort study of adults undergoing out-patient upper endoscopy. Incident cases of EoE were diagnosed per consensus guidelines. Controls were subjects with either GERD or dysphagia without EoE. EoE patients were treated with swallowed/topical steroids and had repeat endoscopy/biopsy. Serum periostin levels for cases and controls were compared at baseline, and pre/post-treatment levels were compared for cases. Serum IL-13 and tissue expression of periostin were also assessed. RESULTS: A total of 61 incident EoE cases and 87 controls were analysed. Despite a marked increase in tissue periostin expression in cases, the median baseline serum periostin level was only slightly higher in cases than controls (22.1 ng/mL vs. 20.7; P = 0.04); there was no change in post-treatment levels. There was also no difference in serum periostin for cases by histologic response or atopic status. There was a strong trend towards higher serum IL-13 levels in cases in the highest periostin quartile (57.1 pg/mL vs. 2.6; P = 0.07). CONCLUSIONS: Serum periostin levels were similar in cases and controls, and there were no changes post-treatment. Given elevated IL-13 levels in the EoE patients with the highest periostin levels, future studies could explore periostin as a biomarker in EoE, perhaps in the setting of anti-IL-13 therapy.

CD80 costimulation is required for Th2 cell cytokine production but not for antigen-specific accumulation and migration into the lung.

The CD28 ligands CD80 and CD86 are expressed on APC, and both provide costimulatory function. However, the reason for the expression of two separate CD28 ligands remains unclear. We have previously shown that blockade of CD80 costimulation by Y100F-Ig, a CTL-associated Ag-4 (CTLA4)-Ig mutant that does not bind CD86, inhibits the development of lung inflammatory immune responses, but does not affect blood eosinophilia or Ab production. Each of those responses was inhibited by treatment with CTLA4-Ig, which binds both CD80 and CD86. To clarify the mechanism underlying these observations we have developed a model of lung inflammation using adoptively transferred CD4(+) T cells expressing a Valpha11(+)Vbeta3(+) transgenic TCR specific for I-E(k) and moth cytochrome c. Treatment with Y100F-Ig inhibited the induction of lung eosinophilia in adoptively transferred mice. However, Y100F-Ig did not detectably affect the accumulation of Ag-specific T cells at the site of peptide deposit or in the draining lymphoid tissues. Acquisition of an activated phenotype and expression of adhesion molecules required for migration into the lung were modestly affected. Importantly, treatment with Y100F-Ig diminished the ability of T cells to produce the cytokines IL-4 and IL-5 following intranasal challenge with Ag. All the responses examined were severely inhibited by treatment with CTLA4-Ig. We conclude that T cells require CD80 costimulation for the optimal production of IL-5 following intranasal administration of Ag. Decreased IL-5 production is the most likely explanation for the diminished airway eosinophilia observed.

CD28-B7-mediated T cell costimulation in chronic cardiac allograft rejection: differential role of B7-1 in initiation versus progression of graft arteriosclerosis.

Provision of adequate T cell costimulation is critical for the development of acute and chronic allograft rejection. We have previously reported that early blockade of CD28-B7 T cell costimulation prevents the development of graft arteriosclerosis, in the LEW into F344 rat cardiac transplant model. In this study, we used the same model to examine the requirement for CD28-B7-mediated T cell costimulation in the progression of established chronic rejection and examined the individual roles of B7-1 (CD80) and B7-2 (CD86) costimulatory molecules. Late blockade of CD28-B7 T cell costimulation by the fusion protein CTLA4Ig, which binds both CD80 and CD86, attenuated the development of transplant arteriosclerosis, mononuclear cell infiltration, and parenchymal fibrosis in this model. Selective blockade of CD80 using the mutant fusion protein Y100F was as effective as CTLA4Ig in this regard. In contrast to CTLA4Ig, blockade of CD80 alone by Y100F was ineffective at preventing early graft loss and prolonging graft survival when given early after transplantation. This study is the first to demonstrate that late blockade of CD28-B7 T cell costimulation interrupts chronic cardiac allograft rejection, and it indicates the importance of continued T cell activation in this process. This study further defines functional differences between CD80 and CD86 costimulatory molecules in vivo.

B7 requirements for primary and secondary protein- and polysaccharide-specific Ig isotype responses to Streptococcus pneumoniae.

The requirements for B7 costimulation during an in vivo humoral response to an intact extracellular bacteria have not been reported. In this study we immunized mice with Streptococcus pneumoniae (R36A) to determine the B7 requirements for induction of Ig, specific for two determinants on R36A, the phosphorylcholine (PC) determinant of C-polysaccharide and pneumococcal surface protein A (PspA). We show that the primary anti-PspA response, the development of PspA-specific memory, and the induction of the secondary anti-PspA response in primed mice were completely dependent upon B7 costimulation. Of note, costimulation was required only briefly after the secondary immunization compared with after the primary immunization for optimal induction of Ig. Blockade of B7 costimulation at the time of secondary immunization also completely abrogated the established state of memory, but did not induce tolerance. In contrast to the anti-PspA response, the primary anti-PC response involved only a very short period of B7 costimulation. Whereas B7-2 alone was required for induction of the primary anti-PspA and anti-PC responses, a redundant role for B7-1 and B7-2 was noted for the PspA-specific secondary response. CTLA4Ig blocked both the anti-PC and anti-PspA responses equally well over a wide range of bacterial doses. These studies demonstrate a critical, but variable, role for B7-dependent costimulation during an Ig response to an extracellular bacteria.

Bacterial pathogens induce abscess formation by CD4(+) T-cell activation via the CD28-B7-2 costimulatory pathway.

Abscesses are a classic host response to infection by many pathogenic bacteria. The immunopathogenesis of this tissue response to infection has not been fully elucidated. Previous studies have suggested that T cells are involved in the pathologic process, but the role of these cells remains unclear. To delineate the mechanism by which T cells mediate abscess formation associated with intra-abdominal sepsis, the role of T-cell activation and the contribution of antigen-presenting cells via CD28-B7 costimulation were investigated. T cells activated in vitro by zwitterionic bacterial polysaccharides (Zps) known to induce abscess formation required CD28-B7 costimulation and, when adoptively transferred to the peritoneal cavity of naïve rats, promoted abscess formation. Blockade of T-cell activation via the CD28-B7 pathway in animals with CTLA4Ig prevented abscess formation following challenge with different bacterial pathogens, including Staphylococcus aureus, Bacteroides fragilis, and a combination of Enterococcus faecium and Bacteroides distasonis. In contrast, these animals had an increased abscess rate following in vivo T-cell activation via CD28 signaling. Abscess formation in vivo and T-cell activation in vitro required costimulation by B7-2 but not B7-1. These results demonstrate that abscess formation by pathogenic bacteria is under the control of a common effector mechanism that requires T-cell activation via the CD28-B7-2 pathway.

Crystallization and preliminary X-ray analysis of CTLA-4 (CD152) membrane-external domain.

CTLA-4 (CD152) is involved in T-lymphocyte co-stimulatory pathways modulating both humoral and cellular immune response. The membrane-external domain has been prepared and crystallized. The unit-cell parameters are a = b = 43, c = 143 A with the symmetry of space group P3(1)21 or its enantiomer and the crystals diffract to 2. 7 A resolution at synchrotron beamlines.

Blockade of costimulation prevents infection-induced immunopathology in interleukin-10-deficient mice.

Interleukin-10 (IL-10) is associated with inhibition of cell-mediated immunity and downregulation of the expression of costimulatory molecules required for T-cell activation. When IL-10-deficient (IL-10KO) mice are infected with Toxoplasma gondii, they succumb to a T-cell-mediated shock-like reaction characterized by the overproduction of IL-12 and gamma interferon (IFN-gamma) associated with widespread necrosis of the liver. Since costimulation is critical for T-cell activation, we investigated the role of the CD28-B7 and CD40-CD40 ligand (CD40L) interactions in this infection-induced immunopathology. Our studies show that infection of mice with T. gondii resulted in increased expression of B7 and CD40 that was similar in wild-type and IL-10KO mice. In vivo blockade of the CD28-B7 or CD40-CD40L interactions following infection of IL-10KO mice with T. gondii did not affect serum levels of IFN-gamma or IL-12, nor did it prevent death in these mice. However, when both pathways were blocked, the IL-10KO mice survived the acute phase of infection and had reduced serum levels of IFN-gamma and alanine transaminase as well as decreased expression of inducible nitric oxide synthase in the liver and spleen. Analysis of parasite-specific recall responses from infected IL-10KO mice revealed that blockade of the CD40-CD40L interaction had minimal effects on cytokine production, whereas blockade of the CD28-B7 interaction resulted in decreased production of IFN-gamma but not IL-12. Further reduction of IFN-gamma production was observed when both costimulatory pathways were blocked. Together, these results demonstrate that the CD28-B7 and CD40-CD40L interactions are involved in the development of infection-induced immunopathology in the absence of IL-10.

CD28-B7 blockade prevents the development of experimental autoimmune glomerulonephritis.

Experimental autoimmune glomerulonephritis (EAG), an animal model of Goodpasture's disease, can be induced in Wistar Kyoto (WKY) rats by a single injection of rat glomerular basement membrane (GBM) in adjuvant. EAG is characterized by circulating and deposited anti-GBM antibodies, accompanied by focal necrotizing glomerulonephritis with crescent formation. The role of T cells in the pathogenesis of EAG remains unclear. T-cell costimulation is provided by ligation of CD28 with either B7.1 (CD80) or B7.2 (CD86) on antigen-presenting cells, and can be inhibited by a soluble form of CTLA4 (CTLA4-Ig) that binds to both B7.1 and B7.2. We examined the effect of CD28-B7 blockade on the development of EAG using native CTLA4-Ig or mutant CTLA4-Ig (Y100F-Ig), which selectively blocks B7.1. Native CTLA4-Ig treatment ameliorated EAG by several measures, including the levels of circulating anti-GBM antibodies, albuminuria, the deposition of IgG and fibrin in the glomeruli, the severity of glomerular abnormalities, and the numbers of infiltrating T cells and macrophages. Y100F-Ig resulted in a similar reduction in the severity of nephritis, but produced no overall reduction in circulating anti-GBM antibodies, although there was a reduction in IgG2a antibodies. We concluded that CD28-B7 blockade reduced autoantibody production and cellular infiltration of glomeruli, and prevented target organ injury. Our results suggest a key role for B7. 1 in costimulation of Th1-like autoimmune responses in the rat, and show that glomerular injury in EAG is largely dependent on cell-mediated mechanisms.

IL-13-mediated worm expulsion is B7 independent and IFN-gamma sensitive.

B7 costimulation is a required component of many type 2 immune responses, including allergy and protective immunity to many nematode parasites. This response includes elevations in Th2 cytokines and associated effector functions including elevations in serum IgG1 and IgE and parasite expulsion. In studies of mice infected with Trichuris muris, blocking B7 ligand interactions inhibited protective immunity, suppressed IL-4 production, and enhanced IFN-gamma production, but unexpectedly did not inhibit production of the Th2 cytokine, IL-13. Blocking both IFN-gamma and B7 restored protective immunity, which was IL-13 dependent, but did not restore IL-4 or associated IgE responses. Although IL-13 was required for worm expulsion in mice in which both IFN-gamma and B7 were blocked, IL-4 could mediate expulsion in the absence of both IL-13 and IFN-gamma. These studies demonstrate that 1) B7 costimulation is required to induce IL-4, but not IL-13 responses; 2) IL-13 is elevated in association with the IFN-gamma response that occurs following inhibition of B7 interactions, but can only mediate IL-4-independent protection when IFN-gamma is also inhibited; and 3) increased IL-13 production, in the absence of increased IL-4 production, is not associated with an IgE response, even in the absence of IFN-gamma.

Differential requirement for CD80 and CD80/CD86-dependent costimulation in the lung immune response to an influenza virus infection.

The CD28 costimulatory pathway is critical to T cell activation. Blockade of the interaction of CD28 with its ligands CD80 and CD86 using CTLA4-Ig has been proposed as a therapy for a number of immune-based disorders. We have used a murine model of influenza virus infection to study the role of CD28-dependent costimulation in the development of antiviral immune responses. In vivo treatment with CTLA4-Ig to block the interaction of CD28 with CD80 and CD86 reduced virus-specific cytotoxicity and IFN-gamma production by bronchoalveolar lavage fluid CD8+ T lymphocytes in vitro. It also resulted in decreased numbers of virus-specific CD8+ T lymphocytes in the bronchoalveolar lavage fluid, lung, and spleen and lowered virus-specific Ab titers. Mice treated with CTLA4-Ig were able to control and clear the virus infection, but this was delayed compared with controls. Treatment with Y100F-Ig, a mutant form of CTLA4-Ig which selectively binds to CD80 and blocks the CD28-CD80 interaction leaving CD28-CD86 binding intact, did not affect Ab production, spleen cytotoxic precursors, or clearance of virus. However, Y100F-Ig treatment had a clear effect on lung effector cell function. Secretion of IFN-gamma by bronchoalveolar lavage fluid CD8+ T lymphocytes in vitro was decreased, and the number of virus-specific CD8+ T lymphocytes in the bronchoalveolar lavage fluid and lungs of infected mice was reduced. These results indicate that CD28-dependent costimulation is important in the antiviral immune response to an influenza virus infection. The individual CD28 ligand, CD80, is important for some lung immune responses and cannot always be compensated for by CD86.

Costimulatory signal blockade in murine relapsing experimental autoimmune encephalomyelitis.

Blockade of the CD28-B7 or CD40L-CD40 T cell costimulatory signals prevents induction of experimental autoimmune encephalomyelitis (EAE). However, the effect of simultaneous blockade of these signals in EAE is unknown. We show that administration of either MR1 (to block CD40L) or CTLA4Ig (to block B7) after immunization or after the first attack protects from EAE. Treatment with a combination of CTLA4Ig and MR1 provides additive protection, and is associated with complete absence of mononuclear cell infiltrates in the central nervous system, and marked suppression of proliferation of primed T cells in the periphery. Selective B7-1 blockade did not protect from EAE. These observations have implications for therapy of autoimmune diseases.