Another option is to engineer DC genetically to either constitutively express immunosuppressive [e.g. IL-4, IL-10, cytotoxic T lymphocyte antigen (CTLA)-4; [56-60]] or apoptosis-inducing [e.g. Fas, tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL); [61-63]] molecules or, conversely, to inhibit expression of immunostimulatory molecules (e.g. CD80/CD86, IL-12; [64-66]). Other methods of tolDC generation include treatment of DC with immunosuppressive cytokines IL-10/TGF-β [67-69] or rapamycin [70], short-term
stimulation with LPS [71], induction of microRNA-23b expression [72] or increasing Wnt signalling by treatment with Wnt-5a [73]. Many of these ex-vivo-generated tolDC are capable of inhibiting pathogenic autoreactive T cell responses GSI-IX in vivo [50]. A variety of tolDC have been tested in animal models of RA. Importantly, a number of tolDC have been shown to have immunotherapeutic potential, i.e. can suppress established arthritis [50, 74]). Not surprisingly, the in-vivo mechanism of action by which these tolDC exert their beneficial effects depends on the type of tolDC administered (reviewed in [74]). For instance, FasL-transduced DC act by
depletion of autoreactive T cells [62], IDO- or CTLA 4 immunoglobulin (Ig)-transduced DC induce FoxP3+ Tregs [75], and dexamethasone/vitamin D3-modulated DC inhibit Th17 cells and enhance IL-10-producing T cells [74]. The positive results from preclinical animal buy JNK inhibitor models have provided strong support for the concept that tolDC can be applied as an immunotherapeutic agent for the treatment of autoimmune diseases. However, animal models of autoimmune disease do not reflect human disease completely and ultimately the safety, feasibility and effectiveness of tolDC therapy can be tested only through clinical trials. Two tolDC trials (in type I diabetes and RA) have been conducted recently [76, 77], and our tolDC trial in RA has also started recently – see section below for more detail. A tolDC trial in MS has not yet been reported, but a recent study by the Martinez-Caceres/Borras group [78]
has shown that myelin peptide-pulsed tolDC can induce anergy in myelin-specific T cells from relapsing–remitting MS patients. Y-27632 manufacturer The group are currently preparing for a tolDC trial in MS in the near future (Eva Martinez-Caceres, personal communication). The first clinical trial with tolDC was carried out by the Giannoukakis/Trucco team at the University of Pittsburgh School of Medicine, and the results were published in 2011 [76]. They conducted a randomized, double-blind, Phase I study with tolDC in patients who had insulin-requiring type I diabetes for at least 5 years. Patients were injected with autologous, monocyte-derived DC that were either unmanipulated (control DC; three patients treated) or were treated ex vivo with anti-sense oligonucleotides targeting the CD40, CD80 and CD86 co-stimulatory molecules (tolDC; seven patients treated).