Oral anti-CD3 monoclonal antibody delays diabetes in non-obese diabetic (NOD) mice: effects on pregnancy and offspring--a preliminary report

γδ T Cell-Secreted XCL1 Mediates Anti-CD3-Induced Oral Tolerance

Oral tolerance is defined as the specific suppression of cellular and/or humoral immune responses to an Ag by prior administration of the Ag through the oral route. Although the investigation of oral tolerance has classically involved Ag feeding, we have found that oral administration of anti-CD3 mAb induced tolerance through regulatory T (Treg) cell generation. However, the mechanisms underlying this effect remain unknown. In this study, we show that conventional but not plasmacytoid dendritic cells (DCs) are required for anti-CD3-induced oral tolerance. Moreover, oral anti-CD3 promotes XCL1 secretion by small intestine lamina propria γδ T cells that, in turn, induces tolerogenic XCR1⁺ DC migration to the mesenteric lymph node, where Treg cells are induced and oral tolerance is established. Consistent with this, TCRδ^-/- mice did not develop oral tolerance upon oral administration of anti-CD3. However, XCL1 was not required for oral tolerance induced by fed Ags, indicating that a different mechanism underlies this effect. Accordingly, oral administration of anti-CD3 enhanced oral tolerance induced by fed MOG_35-55 peptide, resulting in less severe experimental autoimmune encephalomyelitis, which was associated with decreased inflammatory immune cell infiltration in the CNS and increased Treg cells in the spleen. Thus, Treg cell induction by oral anti-CD3 is a consequence of the cross-talk between γδ T cells and tolerogenic DCs in the gut. Furthermore, anti-CD3 may serve as an adjuvant to enhance oral tolerance to fed Ags.

Navigating monoclonal antibody use in breastfeeding women: Do no harm or do little good?

Many neurologic diseases disproportionately affect women, particularly during their reproductive years. For many of these diseases, monoclonal antibodies (mAbs) are becoming widely available as a treatment option, for example, in migraine, multiple sclerosis, and myasthenia gravis. Yet, despite how common pregnancy is (latest estimates suggest that 86% of US women ages 40-44 have given birth), there is a paucity of research on the safety of prescription medications, including mAbs, during the peripartum period. In this article, we focus on the safety of mAbs during breastfeeding. We summarize how pregnancy affects the trajectory of these diseases and explore the benefit derived from mAb therapies. We posit that as neurologists, we are uniquely poised to lead the study of peripartum safety for the mAbs now on the market and provide a framework for their future study.

Updates on Immune Therapies in Type 1 Diabetes

Multiple clinical trials investigating the efficacy and safety of immunotherapeutic interventions in new onset type 1 diabetes (T1D) have failed to yield long term clinical benefit. Lack of efficacy has frequently been attributed to an incomplete understanding of the pathways involved in T1D and the use of single immunotherapeutic agents. Recent mechanistic studies have improved our knowledge of the complex etiopathogenesis of T1D. This in turn has provided the framework for new and ongoing clinical trials in new onset T1D patients and at-risk subjects. Focus has also shifted towards the potential benefits of synergistic combinatorial approaches, both in terms of efficacy and the potential for reduced side effects. These efforts seek to develop intervention strategies that will preserve β-cell function, and ultimately prevent and reverse clinical disease.

Advances in our understanding of the pathophysiology of Type 1 diabetes: lessons from the NOD mouse

T1D (Type 1 diabetes) is an autoimmune disease caused by the immune-mediated destruction of pancreatic β-cells. Studies in T1D patients have been limited by the availability of pancreatic samples, a protracted pre-diabetic phase and limitations in markers that reflect β-cell mass and function. The NOD (non-obese diabetic) mouse is currently the best available animal model of T1D, since it develops disease spontaneously and shares many genetic and immunopathogenic features with human T1D. Consequently, the NOD mouse has been extensively studied and has made a tremendous contribution to our understanding of human T1D. The present review summarizes the key lessons from NOD mouse studies concerning the genetic susceptibility, aetiology and immunopathogenic mechanisms that contribute to autoimmune destruction of β-cells. Finally, we summarize the potential and limitations of immunotherapeutic strategies, successful in NOD mice, now being trialled in T1D patients and individuals at risk of developing T1D.

Combination treatment with anti-CD20 and oral anti-CD3 prevents and reverses autoimmune diabetes

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease, although B cells also play an important role in T1D development. Both T cell- and B cell-directed immunotherapies have shown efficacy in the prevention and reversal of T1D. However, whether the combined strategy of targeting both T and B cells could further improve therapeutic efficacy remains to be explored. We show that combined treatment with intravenous antihuman CD20 (hCD20) and oral anti-CD3 significantly delays diabetes development in prediabetic hCD20 transgenic NOD mice. More importantly, the combined treatment reverses diabetes in >60% of mice newly diagnosed with diabetes. Further mechanistic studies demonstrated that the addition of oral anti-CD3 to the B-cell depletion therapy synergistically enhances the suppressive function of regulatory T cells. Of note, the oral anti-CD3 treatment induced a fraction of interleukin (IL)-10-producing CD4 T cells in the small intestine through IL-10- and IL-27-producing dendritic cells. Thus, the findings demonstrate that combining anti-CD20 and oral anti-CD3 is superior to anti-CD20 monotherapy for restoring normoglycemia in diabetic NOD mice, providing important preclinical evidence for the optimization of B cell-directed therapy for T1D.

Current status of immunomodulatory and cellular therapies in preclinical and clinical islet transplantation

Clinical islet transplantation is a β-cell replacement strategy that represents a possible definitive intervention for patients with type 1 diabetes, offering substantial benefits in terms of lowering daily insulin requirements and reducing incidences of debilitating hypoglycemic episodes and unawareness. Despite impressive advances in this field, a limiting supply of islets, inadequate means for preventing islet rejection, and the deleterious diabetogenic and nephrotoxic side effects associated with chronic immunosuppressive therapy preclude its wide-spread applicability. Islet transplantation however allows a window of opportunity for attempting various therapeutic manipulations of islets prior to transplantation aimed at achieving superior transplant outcomes. In this paper, we will focus on the current status of various immunosuppressive and cellular therapies that promote graft function and survival in preclinical and clinical islet transplantation with special emphasis on the tolerance-inducing capacity of regulatory T cells as well as the β-cells regenerative capacity of stem cells.