Lucienne Chatenoud

Recent Lessons Learned From Prevention and Recent-Onset Type 1 Diabetes Immunotherapy Trials

Type 1 diabetes (T1D) results from the immune system’s misguided attack on insulin-producing pancreatic β-cells, leading to lifelong insulin replacement therapy as well as to the risk for developing disease-associated complications (1–3). Over the past 2–3 decades, the field of clinical research in T1D has seen tremendous growth, including evaluation of a variety of promising immunotherapy approaches for the prevention or reversal of the disorder (4–6). In just the past 2 years, data from >10 trials have been reported, some revealing promising phase II results. However, phase III trials have failed to demonstrate efficacy. In light of these results, an anxiety-provoked question has arisen: Where does the field go from here? To this end, this article presents and elaborates on key emerging questions and recommendations for future immunotherapy trials in T1D. If implemented successfully, such strategies could accelerate the development of therapies with tangible clinical benefit in T1D because they perhaps more appropriately address the complex nature of the disease.nnNearly 30 years after the first immunotherapy clinical trials in type 1 diabetes (T1D), progress has been realized. This progress includes advancements in scientific knowledge (e.g., immune markers, metabolic testing, pathogenesis), the breadth of agents under investigation (Fig. 1), and how clinical trials are increasingly performed as part of major collaborative networks with uniform protocols often bolstered with mechanistic assays. However, shortcomings remain in demonstrating a degree of therapeutic efficacy for recent-onset T1D immunotherapies that is sufficiently robust in terms of risk/benefit to satisfy the requirements for drug registration and approval by regulatory agencies (i.e., Food and Drug Administration, European Medicines Agency). In 2011 and early 2012 after a number of phase I and II recent-onset clinical trials, a series of phase IIB and III recent-onset T1D trials reported their outcomes (7–10). In advance …

The long and winding road towards induction of allograft tolerance in the clinic

For all those among us who lived the history of immunosuppression in clinical transplantation over the last 25 years, the balance is certainly less optimistic than what we could have imagined. The beginning of the 1980s, a time when only corticosteroids, azathioprine and anti-lymphocyte serum were available, represented the starting point of two fascinating decades affording the possibility to use in the clinic a wealth of chemical and biological immunosuppressants, which became more and more selective for defined subsets of immune cells, in particular T lymphocytes, and whose activities were targeted to intracellular processes. However, these approaches were essentially based on immunosuppression which was non-specific, unrelated to the alloantigens involved. Furthermore, as drug association became the rule, we completely lost in clinical practice the benefit of the cell selectivity of the individual agents. Thus, we were left with very potent and broad immunosuppressive protocols, which were certainly effective at preventing acute rejection but not chronic rejection and which, in addition, exposed the patients to a higher risk of infections and tumors, as a consequence of over-immunosuppression. One must admit that these results completely disprove the long-held dogma that acute rejection was the main factor leading to chronic allograft dysfunction, the major justification for using very aggressive immunosuppressive protocols in the early post-transplant period. Should not we step back, facing today’s reality with humility and admitting that although major progress was made the situation is not ideal and that, at least in theory, inducing operational tolerance represents the only solution for this complex situation? The problem is, however, how to accomplish this change within an ethically acceptable frame for the well-being of our patients and considering that with conventional immunosuppressants we achieve about 95% survival one-year post-transplant with almost no acute rejection. This is the topic addressed by the two companion papers from the group of F. Fandrich in this issue of Transplant International presenting results from clinical transfer of a novel cell therapy strategy [1,2]. Back in 2002, these authors described the tolerogenic capacity of a subset of monocytes, they named TAIC for ‘transplant acceptance-inducing cells’ that were initially characterized from the spleen and tested first in a heterotopic heart allograft model in the rat and subsequently in pig recipients of allogeneic lungs [3–5]. The first clinical study (TAIC-I) included recipients of a cadaver kidney transplant and essentially confirmed the feasibility of producing a sufficient number of TAICs under GMP conditions and indicated that the infusion of the cell preparations at the time of transplantation was Correspondence Prof. Lucienne Chatenoud, INSERM U580, Hôpital Necker, 161 rue de Sèvres, 75015 Paris, France. Tel.: +33 1 44 49 53 73; fax: +33 1 44 49 41 00; e-mail: chatenoud@necker.fr

Concise Review: Pluripotent Stem Cell-Derived Cardiac Cells, A Promising Cell Source for Therapy of Heart Failure: Where Do We Stand?

Heart failure is still a major cause of hospitalization and mortality in developed countries. Many clinical trials have tested the use of multipotent stem cells as a cardiac regenerative medicine. The benefit for the patients of this therapeutic intervention has remained limited. Herein, we review the pluripotent stem cells as a cell source for cardiac regeneration. We more specifically address the various challenges of this cell therapy approach. We question the cell delivery systems, the immune tolerance of allogenic cells, the potential proarrhythmic effects, various drug mediated interventions to facilitate cell grafting and, finally, we describe the pathological conditions that may benefit from such an innovative approach. As members of a transatlantic consortium of excellence of basic science researchers and clinicians, we propose some guidelines to be applied to cell types and modes of delivery in order to translate pluripotent stem cell cardiac derivatives into safe and effective clinical trials. Stem Cells 2016;34:34–43

In vivo activation of transferred regulatory T cells specific for third-party exogenous antigen controls GVH disease in mice

Treg cells hold enormous promise for therapeutic application in GVH disease, a lethal complication of allogeneic HSC transplantation. Mouse studies showed that donor‐derived recipient‐specific Treg (rsTreg) cells are far more efficient than polyclonal Treg cells in suppressing GVH disease. However, clinical grade preparations of rsTreg cells carries the risk of containing significant numbers of highly pathogenic recipient‐specific effector T cells. We hypothesized that an alternative approach using Treg cells specific for an exogenous (i.e. nondonor, nonrecipient) Ag (exoTreg cells) can overcome this risk by taking advantage of the bystander suppressive effect of Treg cells. For this, we used a murine model for aggressive GVH disease. We expanded ex vivo exoTreg cells that are primed against the HY Ag, which is only expressed in males. ExoTreg cells supressed GVH disease as efficiently as rsTreg cells in recipient male mice. We also applied this strategy in female mice that do not express this Ag. While exoTreg cells were not effective in female recipients when applied alone, providing the cognate HY Ag in vivo along side effectively activated exoTreg cells and completely abrogated GVH disease, establishing a targeted on/off system to provide a suppressive effect on alloreactive effector T cells.

Organ transplantation and autoimmunity: Common mechanisms common therapies

Immune mechanisms causing the rejection of organ transplants r the occurrence of autoimmune diseases are of course very diferent with respect to the triggering and target antigens involved hat are alloantigens in the case of transplantations versus autoantiens in the case of autoimmunity. However, the effector immune echanisms underlying alloimmune and autoimmune responses re very similar in many respects. These involve the simultaeous intervention of cellular and humoral immune responses, ith a predominance of the one over the other depending on he individual case. In both conditions regulatory T cells play a ajor role in controlling and modulating the pathogenic response. inally, a logical consequence of the aforementioned points, is that he therapeutic strategies and the drugs used in the two condiions are basically the same. Hence the rationale to gather in this ssue of Seminars in Immunology a set of contributions presentng the state of the art of immunotherapy in transplantation and utoimmunity. The first therapeutic approach in both transplantation and utoimmunity has long been based solely on the use of chemical mmunosuppressants, corticosteroids and to a lesser extent of antinflammatory agents. Remarkable results were obtained though he use of these drugs which allowed to implement successful ransplant programs and to control the progression of autoimune diseases; for some of them the prognosis was impressively mproved as in the case systemic lupus erythematosus. Unfortuately, these treatments had the double disadvantage of being nsufficiently effective and to lead to serious side effects linked to irect toxicity and overimmunosuppression (i.e. increased risk of nfections and tumors). The search for new and more effective or etter adapted immunosuppressive agents with less intrinsic toxcity is still an active field of research and the contribution by D. ojciechowski and F. Vincenti presents the case of CTLA4-Ig, an ntagonist of costimulation, approved for the treatment of rheumaoid arthritis and showing great hopes in clinical transplantation as art of maintenance immunosuppression regimens avoiding the se of calcineurin inhibitors (i.e. cyclosporine and FK506) that are ephrotoxic. Despite this progress, if one takes a broader perspective, it is fair o admit that strategies exclusively based on non-specific immunouppression have probably reached their limits. This complex problem has generated major research efforts to nd alternative therapeutic approaches. In the present issue of Semnars in Immunology our aim was to present and critically discuss he present greatest hopes which for many of them have already een applied in the clinic.

Anti-T-Cell Monoclonal Antibodies as Immunosuppressive Agents

Anti-T-cell monoclonal antibodies represent invaluable tools for in vivo human serotherapy. Large panels of anti-T-cell monoclonal antibodies have been produced, which express different specificities and target efficiently functionally distinct T-cell subsets.

Regulation of the β-cell inflammasome and contribution to stress-induced cellular dysfunction and apoptosis

β-Cells may be a source of IL-1β that is produced as inactive pro-IL-1β and processed into biologically-active IL-1β by enzymatic cleavage mediated by the NLRP1-, NLRP3- and NLRC4-inflammasomes. Little is known about the β-cell inflammasomes. NLRP1-expression was upregulated in islet-cells from T2D-patients and by IL-1β+IFNγ in INS-1xa0cells in a histone-deacetylase dependent manner. NLRP3 was downregulated by cytokines in INS-1xa0cells. NLRC4 was barely expressed and not regulated by cytokines. High extracellular K+ reduced cytokine-induced apoptosis and NO production and restored cytokine-inhibited accumulated insulin-secretion. Basal inflammasome expression was JNK1-3 dependent. Knock-down of the ASC interaction domain common for NLRP1 and 3 improved insulin secretion and ameliorated IL-1β and/or glucolipotoxicity-induced cell death and reduced cytokine-induced NO-production. Broad inflammasome-inhibition, but not NLRP3-selective inhibition, protected against IL-1β-induced INS-1 cell-toxicity. We suggest that IL-1β causes β-cell toxicity in part by NLRP1 mediated caspase-1-activation and maturation of IL-1β leading to an autocrine potentiation loop.

Response to the Comment by D. Bresson and M. von Herrath

First of all we would like to thank Dr. von Herrath, who has long-standing experience in transgenic models in which autoimmunity is triggered by viral agents, and who has also been a close collaborator, for the very stimulating comments on our editorial article. It was indeed the aim of our opinion paper to generate debate. We are pleased that the editor has given us the opportunity to express our views in this reply. n nConcerning the mouse models, our purpose was to highlight the preclinical importance of the spontaneous overtly diabetic, but not prediabetic, NOD female model. We agree that this is not, for obvious reasons, an easy model to handle and that some time is needed to get the best results from it. This does not mean at all, however, that CD3 antibodies did not show a high efficacy in other experimental models. We fully acknowledge K. Herolds work in the streptozotocin-induced diabetes model in normal mice [1]. We ourselves provided evidence in support of the efficacy of CD3 antibody treatment in the cyclophosphamide-induced diabetes model in NOD mice [2, 3] and, in collaboration with Dr. von Herrath, the LCMV-induced diabetes model in LCMV GP-RIP transgenic mice [4]. The problem is, however, that in addition to CD3 antibodies, an exceedingly high number of other strategies were effective in disease prevention and/or treatment in these other models that were not active at all in overtly diabetic NOD mice, and which, interestingly enough, have not made it to the clinic so far. n nConcerning the clinical data, the points raised by Drs. Bresson and von Herrath are well taken. We would nevertheless like to express some words of caution about drawing conclusions too fast from the combination of data from trials which were conducted in different ways. In our view, it is neither surprising nor contradictory that the results in the trial conducted by K. Herold did not show a long-term effect in CD3 antibody-treated responder patients, as we observed in our trial. We believe that differences in the design of the study (the European trial was a placebo-controlled phase II study), the patient populations (children and adult patients were enrolled in the American trial, while young children were not included in the European study) and the method used to evaluate β-cell function (the mixed meal test in the American trial versus the clamp test in the European trial) greatly affected the results obtained, generating the apparent discrepancies. We still believe that the significant effect on insulin doses we observed 18 months after just a 6-day treatment in the absence of generalized immunosuppression is in strong support of operational tolerance induction in these patients, whatever the future outcome may be. Of course, we agree with Drs. Bresson and von Herrath that unfortunately at present there are no reliable antigen-specific T cell assays that can directly prove the presence of active tolerance in CD3 antibody-treated responder patients. n nBecause of our long-standing interest in CD3 antibodies not only in autoimmunity, but also in transplantation, we are very pleased that several groups are now interested in applying and refining the strategies for their use. The larger the critical mass around their clinical development, the better the chances that CD3 antibodies may reach the approval stage by regulatory authorities. This is the real struggle we are facing today before we can proceed to a large-scale use of these antibodies that, at least in our view, are endowed with unique tolerogenic properties that no other biological agents have shown so far. Are we wrong? Are we right? Only time will show.

FUTURE GOALS FOR THERAPEUTIC MONOCLONAL ANTIBODIES

Fifteen years of experience in using immunosuppressive monoclonal antibodies for studies predominantly in experimental and clinical transplantation, but also in autoimmunity, has clearly demonstrated the existence of therapeutic activities not shared by conventional chemical immunosuppressants (i.e. corticosteroids, azathioprine, cyclosporine, FK506). Antibodies to CD3 (OKT3) have been remarkably efficacious in reversing severe acute allograft rejection, a clinical situation in which only high-dose steroids and polyclonal antilymphocyte antibodies have similar efficacy.1–3 More importantly, antibodies or genetically engineered molecules to distinct T-cell receptors (CD4, CD4+CD8, CD28/CTLA4Ig, adhesion receptors or adhesins) can promote tolerance, namely, a stable and antigen-specific state of immunological unresponsiveness.4 As a result, a wide variety of experimental situations have been described where T cell-directed monoclonal antibodies have afforded tolerance not only to foreign soluble antigens but also to tissue alloantigens and autoantigens.5–16 Thus, despite the different problems surrounding their production and clinical development, i.e. high cost and side effects (namely, acute cytokine-related syndrome, xenosensitization), continued effort in pursuing the study of therapeutic monoclonals appears worthwhile.