Nalini Vudattu

Sodium chloride inhibits the suppressive function of FOXP3+ regulatory T cells

FOXP3+ Tregs are central for the maintenance of self-tolerance and can be defective in autoimmunity. In multiple sclerosis and type-1 diabetes, dysfunctional self-tolerance is partially mediated by a population of IFNγ-secreting Tregs. It was previously reported that increased NaCl concentrations promote the induction of proinflammatory Th17 cells and that high-salt diets exacerbate experimental models of autoimmunity. Here, we have shown that increasing NaCl, either in vitro or in murine models via diet, markedly impairs Treg function. NaCl increased IFNγ secretion in Tregs, and reducing IFNγ - either by neutralization with anti-IFNγ antibodies or shRNA-mediated knockdown - restored suppressive activity in Tregs. The heightened IFNγ secretion and loss of Treg function were mediated by the serum/glucocorticoid-regulated kinase (SGK1). A high-salt diet also impaired human Treg function and was associated with the induction of IFNγ-secreting Tregs in a xenogeneic graft-versus-host disease model and in adoptive transfer models of experimental colitis. Our results demonstrate a putative role for an environmental factor that promotes autoimmunity by inducing proinflammatory responses in CD4 effector cells and Treg pathways.

Precipitation of Autoimmune Diabetes With Anti-PD-1 Immunotherapy

Immunotherapy targeting T-cell regulatory molecules is highly effective in multiple cancers refractory to standard chemotherapies. However, blocking inhibitory molecules on activated T cells not only increases tumor cell destruction but also can breach tolerance, enabling pathological T cells to react with self-antigens. Indeed, autoimmune endocrinopathies, including hypophysitis, hypopituitarism, and thyroiditis, have been reported in trials involving anti-CTLA-4 and anti-PD-1 monoclonal antibodies (1–3). But autoimmune diabetes has not been definitively linked to these agents. We describe the development of new-onset insulin-dependent diabetes in five patients after receiving anti-PD-1 antibodies, either as single agent or in combination with other cancer drugs. Clinical history and key laboratory findings are summarized in Table 1. Notably, while the patients presented with diverse cancer types, and some had been treated with other immunological agents, their …

A carbon nanotube–polymer composite for T-cell therapy

Clinical translation of cell therapies requires strategies that can manufacture cells efficiently and economically. One promising way to reproducibly expand T cells for cancer therapy is by attaching the stimuli for T cells onto artificial substrates with high surface area. Here, we show that a carbon nanotube-polymer composite can act as an artificial antigen-presenting cell to efficiently expand the number of T cells isolated from mice. We attach antigens onto bundled carbon nanotubes and combined this complex with polymer nanoparticles containing magnetite and the T-cell growth factor interleukin-2 (IL-2). The number of T cells obtained was comparable to clinical standards using a thousand-fold less soluble IL-2. T cells obtained from this expansion were able to delay tumour growth in a murine model for melanoma. Our results show that this composite is a useful platform for generating large numbers of cytotoxic T cells for cancer immunotherapy.

Humanized Mice as a Model for Aberrant Responses in Human T Cell Immunotherapy

Immune-deficient mice, reconstituted with human stem cells, have been used to analyze human immune responses in vivo. Although they have been used to study immune responses to xenografts, allografts, and pathogens, there have not been models of autoimmune disease in which the mechanisms of the pathologic process can be analyzed. We have found that reconstituted “humanized” mice treated with anti–CTLA-4 Ab (ipilimumab) develop autoimmune disease characterized by hepatitis, adrenalitis, sialitis, anti-nuclear Abs, and weight loss. Induction of autoimmunity involved activation of T cells and cytokine production, and increased infiltration of APCs. When anti–CTLA-4 mAb–treated mice were cotreated with anti-CD3 mAb (teplizumab), hepatitis and anti-nuclear Abs were no longer seen and weight loss did not occur. The anti-CD3 blocked proliferation and activation of T cells, release of IFN-γ and TNF, macrophage infiltration, and release of IP-10 that was induced with anti–CTLA-4 mAb. We also found increased levels of T regulatory cells (CD25+CD127−) in the spleen and mesenteric lymph nodes in the mice treated with both Abs and greater constitutive phosphorylation of STAT5 in T regulatory cells in spleen cells compared with mice treated with anti–CTLA-4 mAb alone. We describe a model of human autoimmune disease in vivo. Humanized mice may be useful for understanding the mechanisms of biologics that are used in patients. Hepatitis, lymphadenopathy, and other inflammatory sequelae are adverse effects of ipilimumab treatment in humans, and this study may provide insights into this pathogenesis and the effects of immunologics on autoimmunity.

Changes in T-cell subsets identify responders to FcR-nonbinding anti-CD3 mAb (teplizumab) in patients with type 1 diabetes

The mechanisms whereby immune therapies affect progression of type 1 diabetes (T1D) are not well understood. Teplizumab, an FcR nonbinding anti‐CD3 mAb, has shown efficacy in multiple randomized clinical trials. We previously reported an increase in the frequency of circulating CD8+ central memory (CD8CM) T cells in clinical responders, but the generalizability of this finding and the molecular effects of teplizumab on these T cells have not been evaluated. We analyzed data from two randomized clinical studies of teplizumab in patients with new‐ and recent‐onset T1D. At the conclusion of therapy, clinical responders showed a significant reduction in circulating CD4+ effector memory T cells. Afterward, there was an increase in the frequency and absolute number of CD8CM T cells. In vitro, teplizumab expanded CD8CM T cells by proliferation and conversion of non‐CM T cells. Nanostring analysis of gene expression of CD8CM T cells from responders and nonresponders versus placebo‐treated control subjects identified decreases in expression of genes associated with immune activation and increases in expression of genes associated with T‐cell differentiation and regulation. We conclude that CD8CM T cells with decreased activation and regulatory gene expression are associated with clinical responses to teplizumab in patients with T1D.

Treatment of new onset type 1 diabetes with teplizumab: successes and pitfalls in development

Introduction: Type 1 diabetes is an organ-specific autoimmune disease, characterized by selective destruction of insulin-producing pancreatic β-cells by T-cell-mediated inflammation. Beginning with studies of cyclosporin A in the 1980s, but with more activity in the past decade, there have been a number of clinical trials to test whether immunotherapies can arrest the decline in C-peptide, which is associated with progression of type 1 diabetes leading to the metabolic instability that characterizes the disease. One of the most promising agents, teplizumab, is an FcR-nonbinding anti-CD3 monoclonal antibody that has been tested in Phase II – III clinical trials and was shown to preserve the C-peptide levels and reduce the need for exogenous insulin. Areas covered: In this review, we discuss the recent update on clinical data obtained from trials of teplizumab in type 1 diabetes, the drug’s postulated mechanism of action and the identification of responders to therapy. We highlight the results of recent trials as well as the lessons that have been learned from the clinical trials involving selection of end points and the inclusion of diverse study populations. Expert opinion: Teplizumab has been shown to preserve β cell function in patients; however, it does not represent a ‘cure’ for patients, and its efficacy does entail a significant advance in arresting the progression of the disease toward complete insulin deficiency and reliance on exogenous insulin.

Differential cellular recognition pattern to M. tuberculosis targets defined by IFN-γ and IL-17 production in blood from TB + patients from Honduras as compared to health care workers: TB and immune responses in patients from Honduras

BackgroundA better understanding of the quality of cellular immune responses directed against molecularly defined targets will guide the development of TB diagnostics and identification of molecularly defined, clinically relevant M.tb vaccine candidates.MethodsRecombinant proteins (n = 8) and peptide pools (n = 14) from M. tuberculosis (M.tb) targets were used to compare cellular immune responses defined by IFN-γ and IL-17 production using a Whole Blood Assay (WBA) in a cohort of 148 individuals, i.e. patients with TB + (n = 38), TB- individuals with other pulmonary diseases (n = 81) and individuals exposed to TB without evidence of clinical TB (health care workers, n = 29).ResultsM.tb antigens Rv2958c (glycosyltransferase), Rv2962c (mycolyltransferase), Rv1886c (Ag85B), Rv3804c (Ag85A), and the PPE family member Rv3347c were frequently recognized, defined by IFN-γ production, in blood from healthy individuals exposed to M.tb (health care workers). A different recognition pattern was found for IL-17 production in blood from M.tb exposed individuals responding to TB10.4 (Rv0288), Ag85B (Rv1886c) and the PPE family members Rv0978c and Rv1917c.ConclusionsThe pattern of immune target recognition is different in regard to IFN-γ and IL-17 production to defined molecular M.tb targets in PBMCs from individuals frequently exposed to M.tb. The data represent the first mapping of cellular immune responses against M.tb targets in TB patients from Honduras.

Tumor Antigen-specific T-cells are Present in the CD8αα+ T-cell Effector-memory Pool

CD8+ T-cell memory formation has recently been demonstrated to be associated with CD8αα homodimer expression by T-cells in mice. Up to now, the knowledge about the clinical significance of CD8αα+ T-cells in humans is limited. We assessed in longitudinally collected blood samples from patients with melanoma, who underwent a peptide-based vaccination, the role of CD8αα+ T-cells in tumor-specific cellular immune responses. Phenotypic analysis showed that the expression of CD8αα+ by T-cells was stable over time and associated with a CD45RA+/−CCR7− effector-memory profile. Melan-A/MART-1–specific T-cells were identified in the CD8αα+ T-cell compartment by tetramer technology. Detection of intracellular cytokine production (interleukin-2, interferon-γ, and tumor necrosis factor-α) upon phorbol 12-myristate 13-acetate-ionomycin stimulation in CD8αα+ and CD8αβ+ T-cells revealed that CD8αα+ T-cells show a unique cytokine production pattern (tumor necrosis factor-α and interferon-γ production) as compared with CD8αβ+ T-cells. T-cell receptor-CDR3 length analysis revealed that Melan-A/MART-1–specific CD8αα+ T-cells showed a similar T-cell receptor-repertoire as compared with Melan-A/MART-1–specific CD8αβ+ T-cells. Our results show that CD8αα+ T-cells represent a compartment of CD45RA+/− effector-memory cells in the peripheral circulation of patients with melanoma and suggest that CD8αα+ T-cells may originate from CD8+ T-cells that have down-regulated the expression of the CD8β chain. CD8αα+ and tetramer-specific T-cells may represent a valuable marker to gauge long-term antigen-specific T-cell memory.

Microbiota control immune regulation in humanized mice

The microbiome affects development and activity of the immune system, and may modulate immune therapies, but there is little direct information about this control in vivo. We studied how the microbiome affects regulation of human immune cells in humanized mice. When humanized mice were treated with a cocktail of 4 antibiotics, there was an increase in the frequency of effector T cells in the gut wall, circulating levels of IFN-γ, and appearance of anti-nuclear antibodies. Teplizumab, a non-FcR-binding anti-CD3ε antibody, no longer delayed xenograft rejection. An increase in CD8+ central memory cells and IL-10, markers of efficacy of teplizumab, were not induced. IL-10 levels were only decreased when the mice were treated with all 4 but not individual antibiotics. Antibiotic treatment affected CD11b+CD11c+ cells, which produced less IL-10 and IL-27, and showed increased expression of CD86 and activation of T cells when cocultured with T cells and teplizumab. Soluble products in the pellets appeared to be responsible for the reduced IL-27 expression in DCs. Similar changes in IL-10 induction were seen when human peripheral blood mononuclear cells were cultured with human stool samples. We conclude that changes in the microbiome may impact the efficacy of immunosuppressive medications by altering immune regulatory pathways.

Delayed anti-CD3 therapy in a mouse heart transplant model induced tolerance and long-term survival of allograft: achieving tolerance

Goto R, You S, Zaitsu M, Chatenoud L, Wood KJ. Delayed anti-CD3 therapy results in depletion of alloreactive T cells and the dominance of Foxp3(+) CD4(+) graft infiltrating cells. Am. J. Transplant. 13(7), 1655-1664 (2013). Humanized Fc receptor nonbinding anti-CD3 monoclonal antibodies have been tested in patients with autoimmune diseases with the goal of inducing immune tolerance. However, the timing of drug administration may be an important determinant of the biologic effects, since not all T cells are equally affected, and there may be different subsets of cells involved during the evolution of immune responses. The study by Goto et al. showed that delayed administration of anti-CD3 therapy was more effective in depleting alloreactive T cells than administration at the time of transplant, and resulted in long-term survival of the graft by promoting infiltration of CD4 Tregs into the graft.