Insulin-like growth factor-1 (IGF-1) protects NOD mice from insulitis and diabetes.

To evaluate the effect of IGF-1 on the autoimmune process of beta cell destruction, permissive non-obese diabetic (NOD) recipients were adoptively transferred with 7 x 10(6) autoreactive T cells from diabetic NOD mice and were administered subcutaneously 10 micrograms rhIGF-1, twice daily for 3 weeks. Administration of rhIGF-1 reduced the final incidence of successful transfers of diabetes observed in only 6/24 mice (25%) versus 12/21 (57%) in control mice. A marked reduction of insulitis during histological analysis of pancreatic glands was also observed. Mice treated with rhIGF-1 had a higher percentage of intact islets (48.6 +/- 12% versus 1.6 +/- 1.1%, P = 0.001) and a lower percentage of infiltrated islets. Islets from rhIGF-1-treated mice had a more intense insulin staining reflecting a higher beta cell mass, but no difference was observed in the amount of insulin content of pancreatic extracts and in the amounts of mRNA transcripts for proinsulin. No difference was also observed in the titres of three islet cell antibody (ICA)-positive sera and in the pattern of A2B5 staining. Some mice developed diabetes and severe islet cell infiltration despite rhIGF-1, thus indicating that some committed T cells were still able to invade the islets and cause beta cell destruction. The percentages of CD4+ and CD8+ T cells in the spleen of experimental mice were similar. To evaluate the effects of rhIGF-1 on cell trafficking in recipient mice, T cells from diabetic NOD Thy-1,2 mice injected into congenic NOD-N Thy-1,1 mice were monitored 3 weeks after adoptive cell transfer. The percentage of Thy-1,2+ T cells was significantly reduced in the spleen (10.8 +/- 1.3% versus 17.2 +/- 3.9%, P = 0.004) of rhIGF-1 treated mice in contrast to the thymus (68.4 +/- 7.9% versus 72.87 +/- 6.2%, P = 0.306), suggesting that rhIGF-1 could influence T cell trafficking to the lymphoid organs. The findings that rhIGF-1 has protective effects in autoimmune diabetes opens new perspectives for future experiments as well as for preventive strategies in human type I diabetes.

Autocrine interferon-beta synthesis for gene therapy of HIV infection: increased resistance to HIV-1 in lymphocytes from healthy and HIV-infected individuals.

OBJECTIVE: To explore the possibility of gene therapy of HIV infection based on the multiple antiretroviral activities of interferon (IFN)-beta. DESIGN: We introduced into HIV target cells an IFN-beta gene placed under an expression control ensuring a low and constitutive expression, sufficient to confer a permanent antiviral state without impeding normal cell function. METHODS: We transformed, with an efficacy ranging from 20-55%, peripheral blood lymphocytes (PBL) derived from healthy, seronegative donors, and from asymptomatic HIV-infected individuals by the HMB-KbHuIFN beta retroviral vector carrying the human IFN-beta coding sequence driven by a fragment of the murine H-2Kb gene promoter. RESULTS: The replication rate of the IFN-beta-expressing cells was no different from that of untransformed controls during the 21-day period of in vitro observation. When IFN-beta-transformed, purified CD4+ lymphocytes from healthy donors were HIV-1LAI-infected, virus replication was inhibited and most of the cells survived, in contrast to untransformed CD4+ cells which were all destroyed 12 days after infection. Protection of CD4+ cells from the same donors was also observed in suspensions of IFN-beta-transformed total PBL that were infected with HIV-1LAI. In IFN-beta-transformed PBL from four HIV-infected donors, endogenous HIV replication was decreased and 28-69% of the CD4+ cells survived at the end of the 21 days in culture. In the untransformed control PBL suspensions, all CD4+ cells were destroyed. In long-term experiments, HIV-infected, IFN-beta-transformed cell populations of the lymphocytic CEM and the promonocytic U937 line were kept in culture for 60 days, during which time they remained resistant to HIV infection. CONCLUSION: These results indicate that further exploration of autocrine IFN-beta production for somatic cell gene therapy of HIV infection is warranted.

Oral administration of human insulin to NOD mice generates CD4+ T cells that suppress adoptive transfer of diabetes.

Oral administration of porcine insulin has been shown to be effective in preventing the spontaneous occurrence of diabetes in the Non-Obese Diabetic (NOD) mouse model. In the present study, we demonstrate that feeding 6-week-old female mice with 20 units of human insulin every 2-3 days for 30 days induces an active mechanism of suppression through the generation of regulatory T cells. Adult irradiated NOD males i.v. injected with 5 x 10(6) T cells from the spleens of diabetic female donors and the same number of T cells from the spleens of insulin-fed animals had less successful diabetes transfer than controls (4/15 vs. 8/16, P < 0.001). Protection from clinical diabetes was associated with a reduction in severe insulitis (16.4 +/- 3.6% vs. 52.3 +/- 12.8%, P = 0.023). However, more than 85% of the islets were inflamed. Feeding animals for 15 days reduced the magnitude of this protection since the number of successful transfers after 1 month was comparable (12/17 vs. 14/17) despite a significant delay in diabetes onset (P < 0.001). No difference in the contribution of T cell subsets was noted by cytofluorometry in the spleens of treated animals. When T cell subsets from insulin-fed animals were co-injected with diabetogenic T cells, only purified CD4+ T cells were able to transfer protection since only 3/12 mice became diabetic after 36 days in comparison to 3/6 in the group co-injected with CD4+ T cells from PBS-fed animals, or 5/6 in the group injected with CD8+ T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Human T-cell leukemia virus type I-induced proliferation of human immature CD2+CD3- thymocytes.

The mitogenic activity of human T-cell leukemia virus type I (HTLV-I) is triggering the proliferation of human resting T lymphocytes through the induction of the interleukin-2 (IL-2)/IL-2 receptor autocrine loop. This HTLV-I-induced proliferation was found to be mainly mediated by the CD2 T-cell antigen, which is first expressed on double-negative lymphoid precursors after colonization of the thymus. Thus, immature thymocytes express the CD2 antigen before that of the CD3-TCR complex. We therefore investigated the responsiveness of these CD2+CD3- immature thymocytes and compared it with that of unseparated thymocytes, containing a majority of the CD2+CD3+ mature thymocytes, and that of the CD2-CD3- prothymocytes. Both immature and unseparated thymocytes were incorporating [3H]thymidine in response to the virus, provided that they were cultivated in the presence of submitogenic doses of phytohemagglutinin. In contrast, the prothymocytes did not proliferate. Downmodulation of the CD2 molecule by incubating unseparated and immature thymocytes with a single anti-CD2 monoclonal antibody inhibited the proliferative response to HTLV-I. These results clearly underline that the expression of the CD2 molecule is exclusively required in mediating the proliferative response to the synergistic effect of phytohemagglutinin and HTLV-I. Immature thymocytes treated with a pair of anti-CD2 monoclonal antibodies were shown to proliferate in response to HTLV-I, even in the absence of exogenous IL-2. We further verified that the proliferation of human thymocytes is consecutive to the expression of IL-2 receptors and the synthesis of IL-2. These observations provide evidence that the mitogenic stimulus delivered by HTLV-I is more efficient than that provided by other conventional mitogenic stimuli, which are unable to trigger the synthesis of endogenous IL-2. Collectively, these results show that the mitogenic activity of HTLV-I is able to trigger the proliferation of cells which are at an early stage of T-cell development. They might therefore represent target cells in which HTLV-I infection could favor the initiation of the multistep lymphoproliferative process leading to adult T-cell leukemia.