Relative abilities of 4-1BB (CD137) and CD28 to co-stimulate the response of cytokine deflected Th1 and Th2 cells

Reblastatins Inhibit Phenotypic Changes of Monocytes/Macrophages in a Milieu Rich in 27-Hydroxycholesterol

We investigated effects of reblastatins on phenotypic changes in monocytes/macrophages induced by 27-hydroxycholesterol (27OHChol). Treatment of THP-1 monocytic cells with reblastatin derivatives, such as 17-demethoxy-reblastatin (17-DR), 18-dehydroxyl-17-demethoxyreblastatin (WK88-1), 18-hydroxyl-17-demethoxyreblastatin (WK88-2), and 18-hydroxyl-17-demethoxy-4,5-dehydroreblastatin (WK88-3), resulted in blockage of CCL2, CCL3, and CCL4 expression at the transcription and protein levels, which, in turn, impaired migration of monocytes/macrophages and Jurkat T cells expressing CCR5, and almost complete inhibition of transcription of M1 marker cytokines, like CXCL10, CXCL11, and TNF-α. Reblastatins also downregulated surface CD14 as well as soluble CD14 along with inhibition of LPS response and matrix metalloprotease-9 expression. Surface levels of mature dendritic cell (mDC)-specific markers, including CD80, CD83, CD88, CD197, and MHC class I and II molecules, were remarkably down-regulated, and 27OHChol-induced decrease of endocytic activity was recovered following treatment with 17-DR, WK88-1, WK88-2, and WK88-3. However, 15-hydroxyl-17-demethoxyreblastatin (DHQ3) did not affect the molecular or functional changes in monocytic cells induced by 27OHChol. Furthermore, surface levels of CD105, CD137, and CD166 were also down-regulated by 17-DR, WK88-1, WK88-2, and WK88-3, but not by DHQ3. Collectively, results of the current study indicate that, except DHQ3, reblastatins regulate the conversion and differentiation of monocytic cells to an immunostimulatory phenotype and mDCs, respectively, which suggests possible applications of reblastatins for immunomodulation in a milieu rich in oxygenated cholesterol molecules.

CD137-CD137L interaction regulates atherosclerosis via cyclophilin A in apolipoprotein E-deficient mice

Background

Our previous studies showed that increased levels of cyclophilin A (CyPA) may be a valuable marker for predicting the severity of acute coronary syndromes and that interruption of CD137-CD137L interactions diminished the formation and progression of atherosclerosis in apolipoprotein E-deficient (ApoE−/−) mice. Here, we sought to determine whether the proinflammatory factor CyPA is involved in atherosclerosis regulated by CD137-CD137L interactions.

Methods and Results

A constrictive collar was placed around the right carotid arteries of ApoE−/− mice that were fed a high-fat diet to induce atherosclerotic plaque formation. After that, the mice were intraperitoneally injected with anti-CD137 or anti-CD137L in the presence or absence of the recombinant lentiviral vectors LVTHM-CyPA or pGC-FU-CyPA, respectively. Interestingly, activation of CD137-CD137L was negatively correlated with CyPA expression in vivo and in vitro. Stimulating CD137-CD137L interaction significantly increased CyPA, which was concurrent with the upregulation of proinflammatory cytokines, chemokines and matrix metalloproteinases and resulted in the promotion of atherosclerosis in ApoE-/- mice. Silencing CyPA could eliminate these effects, and restoration of CyPA effectively and consistently attenuated the atherosclerotic suppression phenotypes elicited by the blockade of CD137-CD137L.

Conclusion

These observations suggest that CD137-CD137L interactions mediated via regulation of CyPA contribute to the progression of atherosclerosis.

CD137 stimulation and p38 MAPK inhibition improve reactivity in an in vitro model of glioblastoma immunotherapy

Dendritic cell vaccination has become an interesting option for cancer immunotherapy. Tumor-lysate-pulsed dendritic cells (DC) can prime naïve T cells and induce the regression of established tumors including gliomas as shown in various animal models. Despite hopeful results even in clinical studies, the outcome for many patients is still unsatisfying. In the present study, we tested the combination of tumor-lysate-pulsed dendritic cells (TPDC) with a monoclonal antibody against CD137, a monoclonal antibody against CD25 (daclizumab) and a specific p38 mitogen-activated protein kinase (p38 MAPK) inhibitor (SB203580) for improving immunostimulation in an in vitro model of immunotherapy for human gliomas. We observed a higher secretion of interferon gamma by TPDC-primed peripheral blood mononuclear cells (PBMC) that were incubated with an antibody against CD137 or the p38 MAPK inhibitor. In addition, we observed higher specific lysis of tumor cells after incubation of PBMC with the p38 MAPK inhibitor or the anti-CD137 antibody. In contrast, incubation of TPDC-primed PBMC with the anti-CD25 antibody did enhance neither interferon gamma secretion nor cellular cytotoxicity. Cell depletion experiments demonstrated that the immune reaction induced by TPDC is strongly dependent on CD4-positive and CD8-positive cells. Incubation of DC during maturation and antigen loading with the anti-CD137 antibody did not enhance cytotoxicity and interferon gamma secretion in comparison with application of the anti-CD137 antibody during priming. In conclusion, our data suggest that p38 MAPK inhibition and anti-CD137 antibodies can enhance the immune response against glioblastoma cells.

Expression of CD137 in the cerebral artery after experimental subarachnoid hemorrhage in rats: a pilot study

Inflammation and immunity play a crucial role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). CD137 is recognized as an independent costimulatory molecule of T cells and activator of monocytes. A growing body of evidence indicates that CD137 is vital for inflammation and immunity. Therefore, this study aimed to investigate the expression of CD137 in the basilar artery in a rat SAH model and to clarify the potential role of CD137 in cerebral vasospasm. A total of 107 rats were randomly divided into four groups: control group; day 3, day 5, and day 7 groups. Day 3, day 5, and day 7 groups were all SAH groups. The animals in SAH groups were subjected to injection of autologous blood into cisterna magna twice on day 0 and day 2 and were sacrificed on days 3, 5, and 7, respectively. Cross-sectional area of basilar artery was measured and the CD137 expression was assessed by quantitative real-time PCR, Western blot and immunohistochemistry. The cross-sectional area of basilar artery was found to be 57,944±5581μm(2) in control group, 26,100±2639μm(2) in day 3, 19,723±2412μm(2) in day 5, and 28,800±2980μm(2) in day 7 group, respectively. The basilar artery exhibited vasospasm after SAH and became more severe on day 5. The elevated mRNA and protein of CD137 were detected after SAH and peaked on day 5. CD137 is increasingly expressed in a parallel time course to the development of cerebral vasospasm in a rat experimental model of SAH. These findings indicate the possible role of CD137 in the pathogenesis of cerebral vasospasm after SAH.

Positive correlation between CD137 expression and complex stenosis morphology in patients with acute coronary syndromes

BACKGROUND

CD137, a member of the tumor necrosis factor receptor superfamily, has been reported to be expressed highly in patients with acute coronary syndromes. However, limited information is available on the relationship between CD137 expression and complex stenosis morphology in patients with acute coronary syndromes.

METHODS

Our study included normal controls (n=50), patients with stable angina (SA) (n=80) and patients with acute coronary syndromes (ACS), including unstable angina (UA) (n=70) and acute myocardial infarction (AMI) (n=100). The expression of CD137 in peripheral monocytes was analyzed by flow cytometry. Serum soluble CD137 (sCD137), MMP-9 and MMP-3 levels were measured by enzyme-linked immunosorbent assay kit. All coronary stenoses with ≥50% diameter reduction were assessed by angiographic coronary stenosis morphology.

RESULTS

Patients with ACS(n=170) showed a significant increase of CD137 [23.6±5.7 mean fluorescence intensity (MFI)] expression in peripheral monocytes compared with control (8.4±2.6 MFI) and SA group (7.9±2.1 MFI) (p<0.001). sCD137 also showed higher level in patients with ACS(30.2±8.7 ng/ml) than in control (6.2±1.8 ng/ml) and SA group (7.1±2.1 ng/ml) (p<0.001). Serum MMP-3 and MMP-9 in patients with ACS were 2-times greater than those in control and SA group. A positive correlation was found between MMP-9, MMP-3 and CD137 expression in peripheral monocytes as well as sCD137 levels. An obvious correlation was also observed between soluble or membrane-bound CD137 expression and complex coronary stenoses (r1=0.5548, r2=0.4652, and p<0.001). In the logistic regression model, the independent predictors of ACS were sCD137 (odds ratio 2.671, 95% CI 1.718-4.153, P=0.000), MMP-9 (1.431, 1.043-1.964, P=0.026) and MMP-3 (1.368, 1.038-1.817, P=0.018).

CONCLUSION

Patients with ACS showed significantly positive correlation between CD137 expression and complex coronary stenosis morphology. We speculate that the increased CD137 expression might represent or reflect an instability of atherosclerotic plaques in patients with ACS.

TNF receptor-associated factor 3 is required for T cell-mediated immunity and TCR/CD28 signaling

We recently reported that TNFR-associated factor (TRAF)3, a ubiquitously expressed adaptor protein, promotes mature B cell apoptosis. However, the specific function of TRAF3 in T cells has remained unclear. In this article, we report the generation and characterization of T cell-specific TRAF3(-/-) mice, in which the traf3 gene was deleted from thymocytes and T cells. Ablation of TRAF3 in the T cell lineage did not affect CD4 or CD8 T cell populations in secondary lymphoid organs or the numbers or proportions of CD4(+),CD8(+) or double-positive or double-negative thymocytes, except that the T cell-specific TRAF3(-/-) mice had a 2-fold increase in FoxP3(+) T cells. In striking contrast to mice lacking TRAF3 in B cells, the T cell TRAF3-deficient mice exhibited defective IgG1 responses to a T-dependent Ag, as well as impaired T cell-mediated immunity to infection with Listeria monocytogenes. Surprisingly, we found that TRAF3 was recruited to the TCR/CD28 signaling complex upon costimulation and that TCR/CD28-mediated proximal and distal signaling events were compromised by TRAF3 deficiency. These findings provide insights into the roles played by TRAF3 in T cell activation and T cell-mediated immunity.

CD137 Is Expressed in Human Atherosclerosis and Promotes Development of Plaque Inflammation in Hypercholesterolemic Mice

Background— Atherosclerosis is a multifactorial disease in which inflammatory processes play an important role. Inflammation underlies lesion evolution at all stages, from establishment to plaque rupture and thrombosis. Costimulatory molecules of the tumor necrosis factor superfamily such as CD40/CD40L and OX40/OX40L have been implicated in atherosclerosis.

Methods and Results— This study shows that the tumor necrosis factor superfamily members CD137 and CD137 ligand (CD137L), which play a major role in several autoimmune diseases, may constitute a pathogenic pair in atherogenesis. We detected CD137 protein in human atherosclerotic lesions not only on T cells but also on endothelial cells and showed that CD137 in cultured endothelial cells and smooth muscle cells was induced by proinflammatory cytokines implicated in atherosclerosis. Activation of CD137 by CD137L induced adhesion molecule expression on endothelial cells and reduced smooth muscle cell proliferation. In addition, treatment of atherosclerosis-prone apolipoprotein E–deficient mice with a CD137 agonist caused increased inflammation. T-cell infiltration, mainly of CD8 + cells, and expression of the murine major histocompatibility complex class II molecule I-A b increased significantly in atherosclerotic lesions, as did the aortic expression of proinflammatory cytokines.

Conclusions— Taken together, these observations suggest that CD137-CD137L interactions in the vasculature may contribute to the progression of atherosclerosis via augmented leukocyte recruitment, increased inflammation, and development of a more disease-prone phenotype.

Human CD81 directly enhances Th1 and Th2 cell activation, but preferentially induces proliferation of Th2 cells upon long-term stimulation

BACKGROUND

CD81, a cell-surface protein of the tetraspanin superfamily, has been shown to costimulate T cell activation in murine T cells, and is involved in development of Th2 immune responses in mice.

RESULTS

Here it is shown that stimulation of CD81 on human T cells can enhance T cell activation by antigen or superantigen, causing an increase in the early activation marker CD69, and increasing the number of cytokine-producing and proliferating T cells. Interestingly, CD81 costimulates cytokine production by T cells producing both Th1 and Th2 cytokines. Although human CD81 is highly expressed on non-T as well as T cells, CD81 costimulation appears to act directly on T cells. Pre-incubation of purified T cells with anti-CD81 antibody is sufficient to increase T cell activation, while pre-incubation of non-T cells is not. However, long-term polyclonal stimulation of T cells by anti-CD3 antibody, in the presence of CD81 costimulation, biases T cells towards the production of IL-4 and not IFNgamma. This is accomplished by a preferential proliferation of IL-4-producing cells.

CONCLUSION

Thus, signalling through CD81 on T cells costimulates both Th1 and Th2 cells, but increases the number of Th2 cells during long-term activation.

Preferential blockade of CD8(+) T cell responses by administration of anti-CD137 ligand monoclonal antibody results in differential effect on development of murine acute and chronic graft-versus-host diseases

We investigated the effect of CD137 costimulatory blockade in the development of murine acute and chronic graft-vs-host diseases (GVHD). The administration of anti-CD137 ligand (anti-CD137L) mAb at the time of GVHD induction ameliorated the lethality of acute GVHD, but enhanced IgE and anti-dsDNA IgG autoantibody production in chronic GVHD. The anti-CD137L mAb treatment efficiently inhibited donor CD8(+) T cell expansion and IFN-gamma expression by CD8(+) T cells in both GVHD models and CD8(+) T cell-mediated cytotoxicity against host-alloantigen in acute GVHD. However, a clear inhibition of donor CD4(+) T cell expansion and activation has not been observed. On the contrary, in chronic GVHD, the number of CD4(+) T cells producing IL-4 was enhanced by anti-CD137L mAb treatment. This suggests that the reduction of CD8(+) T cells producing IFN-gamma promotes Th2 cell differentiation and may result in exacerbation of chronic GVHD. Our results highlight the effective inactivation of CD8(+) T cells and the lesser effect on CD4(+) T cell inactivation by CD137 blockade. Intervention of the CD137 costimulatory pathway may be beneficial for some selected diseases in which CD8(+) T cells are major effector or pathogenic cells. Otherwise, a combinatorial approach will be required for intervention of CD4(+) T cell function.