A major goal of immunotherapy for autoimmune diseases and transplantation is induction of regulatory T cells that mediate immunologic tolerance. The mucosal immune system is unique, as tolerance is preferentially induced after exposure to antigen, and induction of regulatory T cells is a primary mechanism of oral tolerance. Parenteral administration of CD3-specific monoclonal antibody is an approved therapy for transplantation in humans and is effective in autoimmune diabetes. We found that orally administered CD3-specific antibody is biologically active in the gut and suppresses autoimmune encephalomyelitis both before induction of disease and at the height of disease. Orally administered CD3-specific antibody induces CD4+ CD25- LAP+ regulatory T cells that contain latency-associated peptide (LAP) on their surface and that function in vitro and in vivo through a TGF-beta-dependent mechanism. These findings identify a new immunologic approach that is widely applicable for the treatment of human autoimmune conditions.

Multiple myeloma (MM) cells specifically attract peripheral-blood monocytes, while interaction of MM with bone marrow stromal cells (BMSCs) significantly increased monocyte recruitment (p<0.01). The CXCL12 chemokine, produced by both the MM and BMSCs, was found to be a critical regulator of monocyte migration. CXCL12 production was up-regulated under MM-BMSCs co-culture conditions, whereas blockage with anti-CXCR4 antibodies significantly abrogated monocyte recruitment toward a MM-derived conditioned medium (p<0.01). Furthermore, elevated levels of CXCL12 were detected in MM, but not in normal BM samples, whereas malignant MM cells often represented the source of increased CXCL12 in the BM. Blood-derived macrophages effectively supported MM cells proliferation and protected them from chemotherapy-induced apoptosis. Importantly, MM cells affected macrophage polarization, elevating the expression of M2-related scavenger receptor CD206 in macrophages and blocking LPS-induced TNFα secretion (a hallmark of M1 response). Of note, MM-educated macrophages suppressed T-cell proliferation and IFNγ production in response to activation. Finally, increased numbers of CXCR4-expressing CD163+CD206+ macrophages were detected in the BM of MM patients (n=25) in comparison to MGUS (n=11) and normal specimens (n=8).Taken together, these results identify macrophages as important players in MM tumorogenicity, and recognize the CXCR4/CXCL12 axis as a critical regulator of MM-stroma interactions and microenvironment formation.

Multiple sclerosis (MS) is postulated to be a T cell-mediated autoimmune disease characterized clinically by a relapsing-remitting (RR) stage followed by a secondary progressive (SP) phase. The progressive phase is felt to be secondary to neuronal degenerative changes triggered by inflammation. The status of the innate immune system and its relationship to the stages of MS is not well understood. Dendritic cells (DCs) are professional APCs that are central cells of the innate immune system and have the unique capacity to induce primary immune responses. We investigated circulating myeloid DCs isolated directly from the blood to determine whether there were abnormalities in myeloid DCs in MS and whether they were related to disease stage. We found that SP-MS subjects had an increased percentage of DCs expressing CD80, a decreased percentage expressing PD-L1, and an increased percentage producing IL-12 and TNF-α compared with RR-MS or controls. A higher percentage of DCs from both RR and SP-MS patients expressed CD40 compared with controls. We then investigated the polarization effect of DCs from MS patients on naive T cells taken from cord blood using a MLR assay. Whereas DCs from RR-MS induced higher levels of Th1 (IFN-γ, TNF-α) and Th2 (IL-4, IL-13) cytokines compared with controls, DCs from SP-MS only induced a polarized Th1 response. These results demonstrate abnormalities of DCs in MS and may explain the immunologic basis for the different stages and clinical patterns of MS.

An increase in the number of stem cells in blood following mobilization is required to enhance engraftment after highdose chemotherapy and improve transplantation outcome. Therefore, an approach that improves stem cell mobilization is essential. The interaction between CXCL12 and its receptor, CXCR4, is involved in the retention of stem cells in the bone marrow. Therefore, blocking CXCR4 may result in mobilization of hematopoietic progenitor and stem cells. We have found that the CXCR4 antagonist known as 4F-benzoyl-TN14003 (T-140) can induce mobilization of hematopoietic stem cells and progenitors within a few hours posttreatment in a dose-dependent manner. Furthermore, although T-140 can also increase the number of white blood cells (WBC) in blood, including monocytes, B cells, and T cells, it had no effect on mobilizing natural killer cells. T-140 was found to efficiently synergize with granulocyte colony-stimulating factor (G-CSF) in its ability to mobilize WBC and progenitors, as well as to induce a 660-fold increase in the number of erythroblasts in peripheral blood. Comparison between the CXCR4 antagonists T-140 and AMD3100 showed that T-140 with or without G-CSF was significantly more potent in its ability to mobilize hematopoietic stem cells and progenitors into blood. These results demonstrate that different CXCR4 antagonists may have different therapeutic potentials.

CXCR4 is a key player in the retention and survival of human acute myeloid leukemia (AML) blasts in the bone marrow (BM) microenvironment. We studied the effects of the CXCR4 antagonist BL-8040 on the survival of AML blasts, and investigated the molecular mechanisms by which CXCR4 signaling inhibition leads to leukemic cell death. Treatment with BL-8040 induced the robust mobilization of AML blasts from the BM. In addition, AML cells exposed to BL-8040 underwent differentiation. Furthermore, BL-8040 induced the apoptosis of AML cells in vitro and in vivo. This apoptosis was mediated by the upregulation of miR-15a/miR-16-1, resulting in downregulation of the target genes BCL-2, MCL-1 and cyclin-D1. Overexpression of miR-15a/miR-16-1 directly induced leukemic cell death. BL-8040-induced apoptosis was also mediated by the inhibition of survival signals via the AKT/ERK pathways. Importantly, treatment with a BCL-2 inhibitor induced apoptosis and act together with BL-8040 to enhance cell death. BL-8040 also synergized with FLT3 inhibitors to induce AML cell death. Importantly, this combined treatment prolonged the survival of tumor-bearing mice and reduced minimal residual disease in vivo. Our results provide a rationale to test combination therapies employing BL-8040 and BCL-2 or FLT3 inhibitors to achieve increased efficacy of these agents.

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Influenza pandemics are imminent and represent a major world health concern. Since vaccinations are expected to be less efficient in the coming years due to newly emerging influenza virus strains, novel antiviral therapies are urgently needed. Here, we show that influenza-infected mice, capable of clearing the virus in the early stages of infection, failed to control inflammation and death. Sequential administration of Interferon-gamma (IFN-gamma) at early stage of the infection protected infected mice from death in a NK cell-dependent manner. IFN-gamma treatment stimulated NK cell proliferation and function and increased their number in the bone marrow, blood, spleen, and infected lungs, keeping viral clearance intact. In parallel, IFN-gamma treatment significantly reduced the number of T cells and NKT cells in the lungs at the inflammatory phase following infection. Thus, rapidly clearing the virus and reducing inflammation by shaping the cellular and cytokine profiles in the early stages of infection may favorably change the fate of influenza pathogenesis.

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