Immune regulatory properties of corticosteroids: prednisone induces apoptosis of human T lymphocytes following the CD3 down-regulation

Neural stem cells secreting bispecific T cell engager to induce selective antiglioma activity

Glioblastoma (GBM) is the most lethal primary brain tumor in adults. No treatment provides durable relief for the vast majority of GBM patients. In this study, we've tested a bispecific antibody comprised of single-chain variable fragments (scFvs) against T cell CD3ε and GBM cell interleukin 13 receptor alpha 2 (IL13Rα2). We demonstrate that this bispecific T cell engager (BiTE) (BiTE^LLON) engages peripheral and tumor-infiltrating lymphocytes harvested from patients' tumors and, in so doing, exerts anti-GBM activity ex vivo. The interaction of BiTE^LLON with T cells and IL13Rα2-expressing GBM cells stimulates T cell proliferation and the production of proinflammatory cytokines interferon γ (IFNγ) and tumor necrosis factor α (TNFα). We have modified neural stem cells (NSCs) to produce and secrete the BiTE^LLON (NSC^LLON). When injected intracranially in mice with a brain tumor, NSC^LLON show tropism for tumor, secrete BiTE^LLON, and remain viable for over 7 d. When injected directly into the tumor, NSC^LLON provide a significant survival benefit to mice bearing various IL13Rα2⁺ GBMs. Our results support further investigation and development of this therapeutic for clinical translation.

T CD3+CD8+ lymphocytes are more susceptible for apoptosis in the first trimester of normal human pregnancy

Aims. Normal human pregnancy is a complex process of many immunoregulatory mechanisms which protect fetus from the activation of the maternal immune system. The aim of the study was to investigate the apoptosis of lymphocytes in peripheral blood of normal pregnant patients and healthy nonpregnant women. Methods. Sixty pregnant women and 17 nonpregnant women were included in the study. Lymphocytes were isolated and labeled with anti-CD3, anti-CD4, and anti-CD8 monoclonal antibodies. Apoptosis was detected by CMXRos staining and analyzed using the flow cytometric method. Results. We found significantly higher apoptosis of total lymphocytes in peripheral blood of pregnant patients when compared to healthy nonpregnant women. The percentage of apoptotic T CD3⁺CD8⁺ cells in the first trimester was significantly higher when compared to the third trimester of normal pregnancy. The ratio of T CD3⁺CD4⁺ : T CD3⁺CD8⁺ apoptotic lymphocytes was significantly lower in the first trimester when compared to other trimesters of pregnancy and to both of the phases of the menstrual cycle. Conclusions. The higher apoptosis of T CD3⁺CD8⁺ lymphocytes and the lower ratio of T CD3⁺CD4⁺ : T CD3⁺CD8⁺ apoptotic cells in the first trimester of normal pregnancy may suggest a higher susceptibility of T CD3⁺CD8⁺ cells for apoptosis as a protective mechanism at the early stage of pregnancy.

Alterations of peripheral blood CD5+ B cells in inflammatory bowel disease

OBJECTIVE

CD5(+) B cells comprise a unique subset of B cells that modulates innate as well as autoimmune systems. The aim of this study was to investigate alterations of the circulating CD5(+) B-cell subset in patients with inflammatory bowel disease (IBD) by evaluating various clinical parameters, including therapeutic regimens.

MATERIAL AND METHODS

Thirty-four patients with ulcerative colitis (UC), 19 patients with Crohn's disease (CD), and 46 healthy control subjects were enrolled in this study. CD5(+) B cells in peripheral blood collected from each subject were analyzed by flow cytometry. Multiple regression analysis was carried out to evaluate the factors related to the circulating CD5(+) B-cell subset in the IBD patients. In an in vitro examination, dexamethasone-induced apoptosis in peripheral blood B cells was examined by detecting cell surface binding of the annexin-V antibody.

RESULTS

Age and gender in the control subjects did not influence the circulating CD5(+) B-cell subset. Multiple regression analysis showed that the presence of UC, corticosteroid therapy, and number of white blood cells in peripheral blood each had a significant influence in decreasing the number of circulating CD5(+) B cells in the IBD patients. Furthermore, in vitro results showed that dexamethasone treatment significantly induced apoptosis in CD5(+) B cells, though apoptosis was similarly observed in CD5(-) B cells.

CONCLUSIONS

CD5(+) B cells may be involved in the pathogenesis of UC, and modulation of this subset by corticosteroid therapy may play a role in the treatment of IBD patients.

A single intravenous dose of prednisolone induces phosphatidylserine externalization, loss of surface marker expression and a 24-h net increase in human peripheral blood lymphocytes ex vivo

To understand how corticosteroids act; a characterization of their effects on lymphocytes is necessary. The effect of in vivo corticosteroids on lymphocyte subpopulations, their surface molecules and externalization of phosphatidylserine (apoptosis) is examined. In a crossover study, a single, intravenous dose of 2 mg/kg prednisolone or saline was given to six male adult human volunteers. Blood samples were withdrawn before and 30 min, 2, 5, 23 and 29 h thereafter. Lymphocyte subsets were determined by FACS analysis. Externalization of phosphatidylserine was measured by Annexin-V; cell fragments were excluded by propidium iodide staining. Lymphocyte number decreased from 2,007 +/- 473 to 634 +/- 119 microl after 5 h and rose to 3,112 +/- 436 microl after 23 h. CD4, CD8 and B cell counts declined significantly after 5 h (P < or = 0.01). The expression of CD28 or CD95 on T cells and the natural killer cells were unaffected. There was a significant rebound of lymphocyte numbers above baseline 23 h after prednisolone. At baseline 9.9 +/- 3.8% of cells in the lymphocyte gate did not stain for CD3, CD20 or CD56 (referred to as "null cells"). 5 h after application of prednisolone, there was a significant increase of "null cells" (28 +/- 12%, P = 0.018). The percentage of phosphatidylserine positive CD4 cells rose from 8.1 +/- 3.3 to 19.8 +/- 8% after intravenous prednisolone, while the percentage of phosphatidylserine positive CD8, B and NK cells remained largely unchanged. Prednisolone induces a most significant depletion of CD4 cells, which to some degree is associated with apoptosis. The net increase of lymphocyte numbers 23 h after prednisolone application may be a beneficial late effect of a single i.v. prednisolone shot.

Endocrine Regulation of Suppressor Lymphocytes: Role of the Glucocorticoid-Induced TNF-Like Receptor

Mechanisms responsible for peripheral immune tolerance are currently under investigation in several laboratories, in order to define the role of immune homeostasis in physiological processes and pathologic conditions, such as autoimmunity and cancer. In this context, recent studies attributed a relevant role to the glucocorticoid-induced TNFR-related gene (GITR). GITR is expressed at high levels on CD4(+)CD25(+). T regulatory (Treg) cells, but only at low levels on resting responder T lymphocytes, and is upregulated after activation. GITR triggering induces both pro- and anti-apoptotic effects through different intracellular pathways, abrogates the suppressive activity of Treg cells, and co-stimulates responder T cells. These data hint that GITR triggering overstimulates the immune system. Indeed, in vivo studies demonstrated that GITR stimulation may both induce autoimmune diseases and strengthen anti-virus and anti-tumor immune responses. Therefore, the GITR-GITRL system appears crucial in regulating immunity. Currently, the majority of studies about GITR's role on regulatory cells are focused on CD4(+)CD25(+) Treg cells, while very little is known about the importance of this molecule in other Treg subtypes. We have recently characterized a subpopulation of CD8+ T suppressor lymphocytes able to inhibit both T cell proliferation and cytotoxicity. Preliminary data show that GITR is expressed on such CD8+ T suppressor cells and that its activation by a specific antibody inhibits generation, but not function, of these cells. These early results suggest the importance of GITR in human T suppressor lymphocytes other than CD4(+)CD25(+) Treg cells.

Enhanced apoptosis of peripheral blood mononuclear cells in cardiac transplanted patients undergoing chronic immunosuppressive treatment

Apoptosis plays a major role in tissue transplantation because intact T-cell-apoptosis pathways are required for the induction of tolerance to allografts. Moreover, immunosuppressive agents commonly used in clinical transplantation medicine promote lymphocyte apoptosis inhibiting the expression and production of cytokines involved in lymphocyte survival. The aim of our study was to evaluate peripheral blood mononuclear cells (PBMC) spontaneous apoptosis in patients undergoing chronic immunosuppressive treatment after cardiac transplantation. PBMC obtained from patients (n = 31) and controls matched for age and sex (n = 25) were cultured for 72 h and apoptosis was evaluated by quantification of fragmented DNA, staining with Hoechst 33258 dye and annexin V binding. We also investigated Fas expression and FasL mRNA expression as well as the ability of an IgM anti-Fas antibody to induce apoptosis. Finally, we evaluated IL2 production induced by PHA and the ability of IL2 to prevent apoptosis. In patients, PBMC underwent enhanced spontaneous apoptosis in comparison with controls. However, we could not find any difference between patients and normals as regards the expression of Fas and of FasL mRNA, even if the cross-linking of the Fas molecule induced apoptosis in PBMC from patients, whereas it failed to induce cell death in normals. We also found that IL2 production was significantly decreased in patients and that the addition of IL2 to the culture medium reduced PBMC spontaneous apoptosis. Our findings suggest that in cardiac transplanted patients PBMC undergo enhanced spontaneous apoptosis, which may contribute to prevent allograft rejection.

Immune homeostasis requires several biologic factors including glucocorticoid hormones

Immunological tolerance can be achieved by several mechanisms including suppressor cells, soluble factors, and neurohormonal mediators. On the cellular level, we isolated a population of CD8+CD28- T cells capable of inhibiting anti-CD3 mAb-induced proliferation of autologous peripheral blood mononuclear cells in an HLA-I nonrestricted manner via production of IFN-gamma and IL-6. Interestingly, CD8+CD28- T cells from systemic lupus erythematosus patients with active disease do not display this inhibitory activity and show a marked imbalance between inhibitory (IL-6) and stimulatory (IL-12) cytokines. For soluble factors, we studied soluble HLA molecules (sHLAs) and double-stranded DNA (ds-DNA). Soluble HLA-I (sHLA-I) molecules induce soluble Fas ligand (sFasL) secretion and trigger apoptosis in phytohemagglutin (PHA)-activated Fas+ T cells. Double-stranded DNA binds to HLA-II molecules and inhibits HLA-II-mediated antigen presentation. On the neurohormonal side, we focused our attention on the immunological activity of corticosteroids (CTSs). CTSs inhibit recirculation of CD4+ T cells, suppress the proliferation and immunological function of activated T cells, and induce apoptosis of activated lymphocytes. Taken together, these data suggest the presence of a complex network of immunoregulatory mechanisms in which CTSs play a strong role supporting their recognized efficacy in the treatment of inflammatory and immunological diseases.

Dexamethazone-induced acute tumor lysis syndrome in a T-cell malignant lymphoma

We report a case of steroid-induced acute tumor lysis syndrome and review the literature. A 60-year-old woman was started on steroid therapy for dyspnea due to bilateral pleural effusion and a large mass involving the anterior mediastinum. The final diagnosis was precursor T-lymphoblastic lymphoma-leukemia. Following steroid therapy, the patient developed acute renal failure and laboratory evidence of metabolic changes induced by massive cytolysis. She received vigorous hydration, diuretic and allopurinol therapy, and haemodialysis. Her diuresis, renal function and laboratory data returned to normal within 2 weeks. A review of the medical literature on T-cell lymphoma revealed only one similar case of steroid-induced acute tumor lysis syndrome, a life-threatening metabolic emergency. This risk should be kept into account in the management of patients with lymphoproliferative disorders.