Phosphate-modif ied CpG oligonucleotides induce in vitro maturation of human myeloid dendritic cells.

Myeloid dendritic cells (DCs) play an important role in the immune response; therefore, the search for compounds that can effectively activate DCs is a needful goal. This study was aimed to investigate the effect of synthetic CpG oligodeoxynucleotides (CpG-ODN) on the maturation and allostimulatory activity of myeloid DCs in comparison with other PAMP and DAMP molecules. For the research, we synthesized known CpG-ODN class C (SD-101 and D-SL03) containing thiophosphate internucleotide groups, and their original phosphate-modified analogues (SD-101M and D- SL03M) with mesylphosphoramide internucleotide groups (M = µ-modification). The effects of CpG-ODN and other activators were evaluated on DCs generated from blood monocytes in the presence of GM-CSF and IFN-α (IFN-DC) or IL-4 (IL4-DC). Evaluation of the intracellular TLR-9 expression showed that both types of DCs (IFN-DC and IL4-DC) contained on average 52 and 80 % of TLR-9-positive cells, respectively. The CpG-ODNs studied enhanced the allostimulatory activity of IFN-DCs, and the effect of µ-modified CpG-ODNs was higher than that of CpG-ODNs with thiophosphate groups. The stimulating effect of CpG-ODN at a dose of 1.0 µg/ml was comparable (for D-SL03, D-SL03M, SD-101) with or exceeded (for SD-101M) the effect of LPS at a dose of 10 µg/ml. At the same time, IFN-DCs were characterized by greater sensitivity to the action of CpG-ODNs than IL4-DCs. The enhancement of DC allostimulatory activity in the presence of CpG-ODNs was associated with the induction of final DC maturation, which was confirmed by a significant decrease in the number of CD14+DC, an increase in mature CD83+DC and a trend towards an increase in CD86+DC. Interestingly, the characteristic ability of LPS to enhance the expression of the co-stimulatory molecule OX40L on DCs was revealed only for the µ-analogue SD-101M. In addition, CpG-ODNs (SD-101 and SD-101M) had a stimulatory effect on IFN-γ production comparable to the action of LPS. The data obtained indicate a stimulating effect of CpG-ODN on the maturation and allostimulatory activity of human myeloid DCs, which is more pronounced for µ-modified analogs.

Role of nitric oxide in activation of human T lymphocytes induced by bacterial superantigen.

The involvement of nitric oxide (NO) in the regulation of human T cell response to bacterial superantigen (staphylococcal enterotoxin B) was studied. It was shown that stimulated T lymphocytes are the main source of NO. This superantigen markedly increased NO production and triggered the proliferative response of mononuclear cells from healthy individuals; the degree of apoptosis was low. In patients with purulent surgical diseases with high spontaneous and induced NO production, superantigen enhanced apoptosis of lymphocytes and induced anergy of T cells to enterotoxins. Increasing the concentration of NO in cultured cells from healthy individuals in the presence of NO donors also stimulated apoptosis and inhibited proliferative activity. These data suggest that NO regulates T lymphocyte response to superantigens. The increased production of NO probably contributes to the development of immunosuppression during bacterial infection.

High-dose immunosuppression with autologous stem cell transplantation in severe refractory systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an immune-mediated disease that is responsive to suppression or modulation of the immune system. Patients with SLE who experience persistent multiorgan dysfunction, despite standard doses of intravenous cyclophosphamide (Cy), represent a subset of patients at high risk of early death. We investigated the efficacy and toxicity of high-dose immunosuppression and autologous hematopoietic stem cell transplantation (SCT) to treat such patients. Six patients (all female, age 15-29 years) with severe refractory SLE were enrolled in the clinic of our institution from 1998 to 2003. All patients were seriously ill, with SLE disease activity indices (SLEDAI) of 6-30, including two cases with central nervous system lupus, one case with lung vasculitis, and three cases with nephritis and nephrotic syndrome. All patients were registered in the European Group for Blood and Marrow Transplantation (EBMT)/European League Against Rheumatism (EULAR) database. Previous immunosuppression included pulse Cy intravenous, prednisolone (standard doses and pulse therapy), oral Cy and azathioprine, with little or no effect on disease progression. Autologous hemopoietic stem cells were collected from bone marrow (n = 4) or mobilized from peripheral blood with Cy and granulocyte colony-stimulating factor (G-CSF) (n = 2). Pre-transplant conditioning regimens included BEAM +/- ATG (n = 2), melphalan 140 mg/m2 + etoposid 1600 mg/m2 (n = 2) and Cy 200 mg/kg +/- ATG (n = 2). Median time to an absolute neutrophil count (ANC) greater than 0.5 x 10(9)/L and platelet count greater than 50 x 10(9)/L was 13 and 15 days, respectively. Three patients died on days 11, 22 and 63 due to transplant-related complications. The follow-up is now 60 and six months for two patients (complete remission), and 42 months for one other patient (partial response). All patients had experienced multiple and severe episodes of infections pre-SCT and long-term history of corticosteroid therapy (3-14 years). We conclude that achievement of prolonged, corticosteroid-free remissions is a reality. Judicious selection of patients earlier in disease or in remission, but with a high risk of relapse or further progression, will diminish transplantation-related mortality.