Current treatments to control pathological or unwanted immune responses often use broadly immunosuppressive drugs. New approaches to induce antigen-specific immunological tolerance that control both cellular and humoral immune responses are desirable. Here we describe the use of synthetic, biodegradable nanoparticles carrying either protein or peptide antigens and a tolerogenic immunomodulator, rapamycin, to induce durable and antigen-specific immune tolerance, even in the presence of potent Toll-like receptor agonists. Treatment with tolerogenic nanoparticles results in the inhibition of CD4+ and CD8+ T-cell activation, an increase in regulatory cells, durable B-cell tolerance resistant to multiple immunogenic challenges, and the inhibition of antigen-specific hypersensitivity reactions, relapsing experimental autoimmune encephalomyelitis, and antibody responses against coagulation factor VIII in hemophilia A mice, even in animals previously sensitized to antigen. Only encapsulated rapamycin, not the free form, could induce immunological tolerance. Tolerogenic nanoparticle therapy represents a potential novel approach for the treatment of allergies, autoimmune diseases, and prevention of antidrug antibodies against biologic therapies.U ndesired immunogenicity can have a profound impact on human health. Allergies, including allergic asthma and severe food allergies, affect ∼20% of the population, and the prevalence has been steadily increasing over the past several decades (1). The prevalence of autoimmune diseases, including multiple sclerosis and type 1 diabetes, is ∼4.5% (2). Unwanted immunogenicity can also affect both efficacy and safety of biologic drugs (3), particularly in the case of protein replacement therapies for the treatment of genetic deficiencies, such as hemophilia A (4) and Pompe Disease (5). Immunomodulatory agents commonly used to control immunogenicity are often broadly immunosuppressive and typically require chronic administration that can lead to reactivation of latent pathogens, development of tumors, and opportunistic infections (6, 7). Therefore, antigen-specific, durable tolerogenic therapy would be highly desirable from an efficacy and safety perspective.Multiple techniques for antigen-specific immunotherapy have been described, although only allergen immunotherapy, wherein low doses of antigen are delivered in the absence of immunomodulating agents, is currently used in the clinic (1). Experimental approaches have included oral administration of antigen, high dose tolerance, and the use of altered peptide ligands (8). Although these methods have been successful in preclinical models, translation to human clinical trials has been largely disappointing (8). Alternative strategies to leverage tolerogenic programming associated with apoptotic cells include conjugating antigen to splenocytes (9-12) or synthetic microparticles (13, 14) or targeting antigen to the surface of red blood cells (15). Other approaches include loading particles with MHC complexes that present relevant peptides i...

Since their discovery by Steinman and Cohn in 1973, dendritic cells (DCs) have become increasingly recognized for their crucial role as regulators of innate and adaptive immunity. DCs are exquisitely adept at acquiring, processing and presenting antigens to T cells. They also adjust the context (and hence the outcome) of antigen presentation in response to a plethora of environmental inputs that signal the occurence of pathogens or tissue damage. Such signals generally boost DC maturation, which promotes their migration from peripheral tissues into and within secondary lymphoid organs and their capacity to induce and regulate effector T cell responses. Conversely, more recent observations indicate that DCs are also crucial to ensure immunological peace. Indeed, DCs constantly present innocuous self and non-self antigens in a fashion that promotes tolerance, at least in part, through the control of regulatory T cells (Tregs). Tregs are specialized T cells that exert their immuno-suppressive function through a variety of mechanisms affecting both DCs and effector cells. Here, we review recent advances in our understanding of the relationship between tolerogenic DCs and Tregs.

PURPOSE Assessing measurable residual disease (MRD) has become standard with many tumors, but the clinical meaning of MRD in multiple myeloma (MM) remains uncertain, particularly when assessed by next-generation flow (NGF) cytometry. Thus, we aimed to determine the applicability and sensitivity of the flow MRD-negative criterion defined by the International Myeloma Working Group (IMWG). PATIENTS AND METHODS In the PETHEMA/GEM2012MENOS65 trial, 458 patients with newly diagnosed MM had longitudinal assessment of MRD after six induction cycles with bortezomib, lenalidomide, and dexamethasone (VRD), autologous transplantation, and two consolidation courses with VRD. MRD was assessed in 1,100 bone marrow samples from 397 patients; the 61 patients without MRD data discontinued treatment during induction and were considered MRD positive for intent-to-treat analysis. The median limit of detection achieved by NGF was 2.9 × 10−6. Patients received maintenance (lenalidomide ± ixazomib) according to the companion PETHEMA/GEM2014MAIN trial. RESULTS Overall, 205 (45%) of 458 patients had undetectable MRD after consolidation, and only 14 of them (7%) have experienced progression thus far; seven of these 14 displayed extraosseous plasmacytomas at diagnosis and/or relapse. Using time-dependent analysis, patients with undetectable MRD had an 82% reduction in the risk of progression or death (hazard ratio, 0.18; 95% CI, 0.11 to 0.30; P < .001) and an 88% reduction in the risk of death (hazard ratio, 0.12; 95% CI, 0.05 to 0.29; P < .001). Timing of undetectable MRD (after induction v intensification) had no impact on patient survival. Attaining undetectable MRD overcame poor prognostic features at diagnosis, including high-risk cytogenetics. By contrast, patients with Revised International Staging System III status and positive MRD had dismal progression-free and overall survivals (median, 14 and 17 months, respectively). Maintenance increased the rate of undetectable MRD by 17%. CONCLUSION The IMWG flow MRD-negative response criterion is highly applicable and sensitive to evaluate treatment efficacy in MM.

The development of antidrug antibodies (ADAs) is a common cause for the failure of biotherapeutic treatments and adverse hypersensitivity reactions. Here we demonstrate that poly(lactic-co-glycolic acid) (PLGA) nanoparticles carrying rapamycin, but not free rapamycin, are capable of inducing durable immunological tolerance to co-administered proteins that is characterized by the induction of tolerogenic dendritic cells, an increase in regulatory T cells, a reduction in B cell activation and germinal centre formation, and the inhibition of antigen-specific hypersensitivity reactions. Intravenous co-administration of tolerogenic nanoparticles with pegylated uricase inhibited the formation of ADAs in mice and non-human primates and normalized serum uric acid levels in uricase-deficient mice. Similarly, the subcutaneous co-administration of nanoparticles with adalimumab resulted in the durable inhibition of ADAs, leading to normalized pharmacokinetics of the anti-TNFα antibody and protection against arthritis in TNFα transgenic mice. Adjunct therapy with tolerogenic nanoparticles represents a novel and broadly applicable approach to prevent the formation of ADAs against biologic therapies.

Activation of the naive T-helper lymphocyte (Thp) directs it down one of two major developmental pathways called Th1 and Th2. Signals transmitted by T cell, co-stimulatory and cytokine receptors control Thp lineage commitment but the mechanism by which these signals are integrated remains a mystery. The interferon-gamma (IFNGR) and interleukin 4 (IL-4R) cytokine receptors, in particular, direct the earliest stages of T-helper commitment. Here we report that on engagement of the T-cell receptor (TCR) on Thp cells, rapid co-polarization of IFNGR with the TCR occurs within the developing immunological synapse. Thp cells from the intrinsically Th1-like C57BL/6 mouse strain have significantly more receptor co-polarization than Th2-prone BALB/c Thp cells. Remarkably, in the presence of IL-4, a cytokine required for Th2 differentiation, IFNGR co-polarization with TCR is prevented. This inhibition depends on Stat6, the transcription factor downstream of IL-4R that is required for Th2 differentiation. This cytokine receptor crossregulation provides an explanation for the effect of IL-4 in inhibiting Th1 differentiation. These observations suggest a scenario in which physical co-polarization of critical receptors directs the fate of the naive Thp, and offer a novel function for the immunological synapse in directing cell differentiation. They further suggest a new mechanism of membrane-bound signalling control by the physical disruption of large receptor-rich domains on signalling through a functionally antagonistic receptor.