First-in-human, double-blind, randomized phase 1b study of peptide immunotherapy IMCY-0098 in new-onset type 1 diabetes: an exploratory analysis of immune biomarkers.

BACKGROUND: IMCY-0098, a synthetic peptide developed to halt disease progression via elimination of key immune cells in the autoimmune cascade, has shown a promising safety profile for the treatment of type 1 diabetes (T1D) in a recent phase 1b trial. This exploratory analysis of data from that trial aimed to identify the patient biomarkers at baseline associated with a positive response to treatment and examined the associations between immune response parameters and clinical efficacy endpoints (as surrogates for mechanism of action endpoints) using an artificial intelligence-based approach of unsupervised explainable machine learning. METHODS: We conducted an exploratory analysis of data from a phase 1b, dose-escalation, randomized, placebo-controlled study of IMCY-0098 in patients with recent-onset T1D. Here, a panel of markers of T cell activation, memory T cells, and effector T cell response were analyzed via descriptive statistics. Artificial intelligence-based analyses of associations between all variables, including immune responses and clinical responses, were performed using the Knowledge Extraction and Management (KEM®) v 3.6.2 analytical platform. RESULTS: The relationship between all available patient data was investigated using unsupervised machine learning implemented in the KEM® environment. Of 15 associations found for the dose C group (450 µg subcutaneously followed by 3 × 225 µg subcutaneously), seven involved human leukocyte antigen (HLA) type, all of which identified improvement/absence of worsening of disease parameters in DR4+ patients and worsening/absence of improvement in DR4- patients. This association with DR4+ and non-DR3 was confirmed using the endpoints normalized area under the curve C-peptide from mixed meal tolerance tests where presence of DR4 HLA haplotype was associated with an improvement in both endpoints. Exploratory immune analysis showed that IMCY-0098 dose B (150 µg subcutaneously followed by 3 × 75 µg subcutaneously) and dose C led to an increase in presumed/potentially protective antigen-specific cytolytic CD4+ T cells and a decrease in pathogenic CD8+ T cells, consistent with the expected mechanism of action of IMCY-0098. The analysis identified significant associations between immune and clinical responses to IMCY-0098. CONCLUSIONS: Promising preliminary efficacy results support the design of a phase 2 study of IMCY-0098 in patients with recent-onset T1D. TRIAL REGISTRATION: ClinicalTrials.gov NCT03272269; EudraCT: 2016-003514-27.

Suppression of Immune Response to Adenovirus Serotype 5 Vector by Immunization with Peptides Containing an MHC Class II Epitope and a Thio-Oxidoreductase Motif.

The main obstacle to viral vector-mediated gene therapy remains the elicitation of an immune response to the vector, resulting in clearance of transgene and resistance to further transgenesis. Specific antibody production contributes to such immune responses. A single class II-restricted epitope of adenovirus serotype 5 (Ad5) vector hexon-6 capsid protein containing a thiol-oxidoreductase motif was used in an attempt to prevent specific antibody production in response to Ad5 vectors. We demonstrate here that such immunization carried out before intravenous administration of Ad5 vectors prevents antibody production to the ensemble of Ad5 vector proteins in both BALB/c and C57BL/6 mice. The antibody response to Ad5 is dependent on innate immune activation, seemingly involving natural killer T (NKT) cells. We observed that immunization with a class II-restricted Ad5 peptide prevents such NKT cell activation. Increased transgenesis and prolonged transgene expression result from such immunization, providing a simple protocol for improving gene therapy.

B-lymphocytes as key players in chemical-induced asthma.

T-lymphocytes and B-lymphocytes are key players in allergic asthma, with B-lymphocytes producing antigen-specific immunoglobulins E (IgE). We used a mouse model of chemical-induced asthma and transferred B-lymphocytes from sensitized animals into naïve wild type mice, B-lymphocyte knock-out (B-KO) mice or severe combined immunodeficiency (SCID) mice. On days 1 and 8, BALB/c mice were dermally sensitized with 0.3% toluene diisocyanate (TDI) (20 µl/ear). On day 15, mice were euthanized and the auricular lymph nodes isolated. B-lymphocytes (CD19(+)) were separated from the whole cell suspension and 175,000 cells were injected in the tail vein of naïve wild type, B-KO or SCID mice. Three days later, the mice received a single oropharyngeal challenge with 0.01% TDI (20 µl) or vehicle (acetone/olive oil (AOO)) (controls). Airway reactivity to methacholine and total and differential cell counts in the bronchoalveolar lavage (BAL) fluid were measured 24 hours after challenge. B-lymphocytes of AOO or TDI-sensitized mice were characterized for the expression of surface markers and production of cytokines. We found that transfer of B-cells obtained from mice dermally sensitized to toluene diisocyanate (TDI) into naïve wild type mice, B-KO mice or SCID mice led, within three days, to an acute asthma-like phenotype after an airway challenge with TDI. This response was specific and independent of IgE. These B-lymphocytes showed antigen presenting capacities (CD80/CD86 and CD40) and consisted of B effector (Be)2- (IL-4) and Be1-lymphocytes (IFN-γ). The transferred B-lymphocytes were visualized near large airways, 24 hours after TDI challenge. Thus, B-lymphocytes can provoke an asthmatic response without the action of T-lymphocytes and without major involvement of IgE.

Increased synapse formation obtained by T cell epitopes containing a CxxC motif in flanking residues convert CD4+ T cells into cytolytic effectors.

The nature of MHC class II-binding epitopes not only determines the specificity of T cell responses, but may also alter effector cell functions. Cytolytic CD4+ T cells have been observed primarily in anti-viral responses, but very little is known about the conditions under which they can be elicited. Their potential as regulators of immune responses, however, deserves investigations. We describe here that inclusion of a thiol-disulfide oxidoreductase motif within flanking residues of class II-restricted epitopes results, both in vitro and in vivo, in elicitation of antigen-specific cytolytic CD4+ T cells through increased synapse formation. We show that both naïve and polarized CD4+ T cells, including Th17 cells, can be converted by cognate recognition of such modified epitopes. Cytolytic CD4+ T cells induce apoptosis on APCs by Fas-FasL interaction. These findings potentially open the way towards a novel form of antigen-specific immunosuppression.

Circulating apoptotic endothelial cells and apoptotic endothelial microparticles independently predict the presence of cardiac allograft vasculopathy.

OBJECTIVES: Maintenance of endothelial homeostasis may prevent the development of cardiac allograft vasculopathy (CAV). This study investigated whether biomarkers related to endothelial injury and endothelial repair discriminate between CAV-negative and CAV-positive heart transplant recipients. BACKGROUND: CAV is the most important determinant of cardiac allograft survival and a major cause of death after heart transplantation. METHODS: Fifty-two patients undergoing coronary angiography between 5 and 15 years after heart transplantation were recruited in this study. Flow cytometry was applied to quantify endothelial progenitor cells (EPCs), circulating endothelial cells (CECs), and endothelial microparticles. Cell culture was used for quantification of circulating EPC number and hematopoietic progenitor cell number and for analysis of EPC function. RESULTS: The EPC number and function did not differ between CAV-negative and CAV-positive patients. In univariable models, age, creatinine, steroid dose, granulocyte colony-forming units, apoptotic CECs, and apoptotic endothelial microparticles discriminated between CAV-positive and CAV-negative patients. The logistic regression model containing apoptotic CECs and apoptotic endothelial microparticles as independent predictors provided high discrimination between CAV-positive and CAV-negative patients (C-statistic 0.812; 95% confidence interval: 0.692 to 0.932). In a logistic regression model with age and creatinine as covariates, apoptotic CECs (p = 0.0112) and apoptotic endothelial microparticles (p = 0.0141) were independent predictors (C-statistic 0.855; 95% confidence interval: 0.756 to 0.953). These 2 biomarkers remained independent predictors when steroid dose was introduced in the model. CONCLUSIONS: The high discriminative ability of apoptotic CECs and apoptotic endothelial microparticles is a solid foundation for the development of clinical prediction models of CAV.

Antielastin B-cell and T-cell immunity in patients with chronic obstructive pulmonary disease.

RATIONALE: Antielastin autoimmunity has been hypothesised to drive disease progression in chronic obstructive pulmonary disease (COPD). The proposed mechanism is currently disputed by conflicting data. The authors aimed to explore antibody responses against elastin in a large and extensively characterised COPD population and to assess elastin-specific peripheral T-cell reactivity in a representative subgroup. METHODS: Antielastin antibodies were analysed with indirect ELISA on the plasma of 320 patients with COPD (Global Initiative for Chronic Obstructive Lung Disease 1-4) and 143 smoking controls. In a second group of 40 patients with COPD and smoking controls, T-cell responses against extracellular matrix (elastin, collagen I and collagen V) were determined with enzyme-linked immunosorbent spot (EliSpot) (interferon γ (IFNγ) and interleukin-2) on peripheral blood mononuclear cells and compared with the responses of 11 never-smoking controls. RESULTS: Antielastin antibody titres were not elevated in patients with COPD compared with smoking controls and even decreased significantly with increasing severity of COPD (p<0.001). Lower antielastin antibody titres were also found in a subgroup of patients with CT-proven emphysema. Elastin-specific INFγ-mediated T helper 1 responses could not be revealed in smoking subjects with and without COPD. Collagen I-mediated T-cell responses were also absent, which contrasted with a significant increased anticollagen V response in the smoking controls and patients with COPD compared with the never smokers (p=0.008). Collagen V-mediated T-cell responses could not discriminate between patients with COPD and smoking controls. CONCLUSION: A systemic immune response against elastin could not be identified in patients with COPD. By contrast, collagen V-mediated autoimmunity was increased in the subgroup of smokers and may potentially contribute to the pathogenesis of COPD.

Topical HDL administration reduces vein graft atherosclerosis in apo E deficient mice.

OBJECTIVE: Use of autologous vein grafts for surgical revascularisation is limited by vein graft failure. Topical high-density lipoprotein (HDL) administration on the adventitial side of vein grafts was evaluated as a new therapeutic modality to improve vein graft patency and function. METHODS: Caval veins of C57BL/6 apo E(-/-) mice were grafted to the right carotid arteries of recipient 3 month-old C57BL/6 TIE2-LacZ/apo E(-/-) mice. HDL (200 µg/ml; 50 µl) in 20% pluronic F-127 gel was applied on the adventitial side of vein grafts. RESULTS: Topical HDL application reduced intimal area by 55% (p < 0.001) at day 28 compared to control mice. Blood flow quantified by micro magnetic resonance imaging at day 28 was 2.8-fold (p < 0.0001) higher in grafts of topical HDL treated mice than in control mice. Topical HDL potently reduced intimal inflammation and resulted in enhanced endothelial regeneration as evidenced by a 1.9-fold (p < 0.05) increase in the number of CD31 positive endothelial cells. HDL potently enhanced migration and adhesion of endothelial colony-forming cells (ECFCs) in vitro, and these effects were dependent on signaling via scavenger receptor-BI, extracellular signal-regulated kinases, and NO, and on increased ß1 integrin expression. Correspondingly, the number of CD31 ß-galactosidase double positive cells, reflecting incorporated circulating progenitor cells, was 3.9-fold (p < 0.01) higher in grafts of HDL treated mice than in control grafts. CONCLUSIONS: Topical HDL administration on the adventitial side of vein grafts attenuates vein graft atherosclerosis via increased incorporation of circulating progenitor cells in the endothelium, enhanced endothelial regeneration, and reduced intimal inflammation.

Retroviral vectors induce epigenetic chromatin modifications and IL-10 production in transduced B cells via activation of toll-like receptor 2.

The immune response toward viral vectors used for gene therapy and genetic vaccination appears to be critically important in determining the therapeutic outcome. However, the mechanisms that control the immune response following gene transfer are poorly understood. Unexpectedly, we found that integrating retroviral vector particles induce stable interleukin-10 (IL-10) production in murine (BALB/c H-2(d)) transduced B cells. This requires a novel mechanism whereby the interaction of retroviral vector particle with its cognate cellular receptor activates intracellular signaling pathways resulting in stable epigenetic modifications. Murine B cells exposed to retroviral vector particles triggered the colocalization of the retroviral cellular receptor [mouse cationic amino acid transporter 1 (mCAT1)] and Toll-like receptor 2 (TLR2) into lipid microrafts, which in turn activated TLR2 signaling pathways. TLR2 activation induced STAT3 phosphorylation and increased phosphorylated histone 3 (H3) at the STAT3-binding site of the IL-10 promoter. In addition, TLR2 activation during transduction activates nuclear factor of κ light polypeptide gene enhancer in B-cells inhibitor, α (NFKBIA), thereby preventing the translocation of the nuclear factor-κB (NF-κB) complex to the nucleus and the transcription of proinflammatory cytokines. These findings open new perspectives for controlling immune responses following gene therapy and genetic vaccination.

In vivo induction of type 1-like regulatory T cells using genetically modified B cells confers long-term IL-10-dependent antigen-specific unresponsiveness.

Regulatory T cells (Tregs) hold much promise for the therapy of allergy and autoimmunity, but their use is hampered by lack of Ag specificity (natural Tregs) and difficulty to expand in vitro or in vivo (adaptive Tregs). We designed a method for in vivo induction of Ag-specific Tregs, in BALB/c H-2d, that share characteristics with type 1 Tregs (Tr1). A retroviral vector was constructed encoding a major T cell epitope of a common allergen, Der p 2, fused to an endosomal targeting sequence (gp75) for efficient MHC class II presentation. B cells transduced with such construct were adoptively transferred to BALB/c mice before or after peptide immunization. Long-lasting Ag-specific immune tolerance was achieved in both cases. Genetically modified B cells constitutively expressed the transgene for at least 3 mo. B cells from IL-10(-/-) mice were unable to induce tolerance. Upon transfer, B cells induced Foxp3(-)CD4(+) T cells showing phenotypic and functional characteristics comparable to Tr1-cells, including production of IL-10 but not of TGF-beta, and high expression of CTLA-4. Adoptive transfer of such T cells conferred unresponsiveness to allergen immunization and prevented the development of Der p 2-induced asthma. Functional Tr1-like cells can therefore be induced in vivo using retrovirally transduced B cells.

Critical role of scavenger receptor-BI-expressing bone marrow-derived endothelial progenitor cells in the attenuation of allograft vasculopathy after human apo A-I transfer.

Allograft vasculopathy is the leading cause of death in patients with heart transplantation. Accelerated endothelial regeneration mediated by enhanced endothelial progenitor cell (EPC) incorporation may attenuate the development of allograft vasculopathy. We investigated the hypothesis that modulation of EPC biology and attenuation of allograft vasculopathy by increased high-density lipoprotein cholesterol after human apo A-I (AdA-I) transfer requires scavenger receptor (SR)-BI expression in bone marrow-derived EPCs. After AdA-I transfer, the number of circulating EPCs increased 2.0-fold (P < .001) at different time points in C57BL/6 mice transplanted with SR-BI(+/+) bone marrow but remained unaltered in mice with SR-BI(-/-) bone marrow. The effect of high-density lipoprotein on EPC migration in vitro requires signaling via SR-BI and extracellular signal-regulated kinases and is dependent on increased nitric oxide (NO) production in EPCs. Human apo A-I transfer 2 weeks before paratopic artery transplantation reduced intimal area at day 21 3.7-fold (P < .001) in mice with SR-BI(+/+) bone marrow but had no effect in mice with SR-BI(-/-) bone marrow. AdA-I transfer potently stimulated EPC incorporation and accelerated endothelial regeneration in chimeric SR-BI(+/+) mice but not in chimeric SR-BI(-/-) mice. In conclusion, human apo A-I transfer accelerates endothelial regeneration mediated via SR-BI expressing bone marrow-derived EPCs, thereby preventing allograft vasculopathy.

Three-dimensional structure and IgE-binding properties of mature fully active Der p 1, a clinically relevant major allergen.

BACKGROUND: Der p 1 is a 25-kd allergen with cysteine protease activity. Sensitization to Der p 1 affects a large proportion of individuals with allergy, resulting in rhinitis, asthma, and/or atopic dermatitis. OBJECTIVE: We determined the Der p 1 crystallographic structure to understand the relationships among structure, function, and allergenicity. METHODS: Recombinant pro-Der p 1 was produced in Pichia pastoris and allowed to mature spontaneously before purification by a 2-step procedure. Protease activity was checked by using a fluorogenic peptide substrate. Allergenicity was analysed by IgE binding assays and basophil activation test. The determination of the 3-dimensional structure was obtained by X-ray crystallography at 1.9 A resolution. RESULTS: The recombinant protein is fully active and expresses an allergenicity equivalent to its natural counterpart. Der p 1 exhibits a cysteine protease fold typical of the papain family, has a magnesium binding site, and forms dimers with a large interface. The crystal lattice shows that the dimers are tightly packed in a compact double layer of proteins. Such an assembly likely exists in dry fecal pellets, the natural form of allergen exposure, and appears ideal to interact with cell surface and trigger allergic inflammation. CONCLUSION: We present here the 3-dimensional structural features of mature fully active Der p 1, one of the main allergens involved in human allergic diseases. This opens the possibility to evaluate the importance of enzymatic activity in pathology and possible new therapeutic interventions.

CD4+CD25+ T cells lyse antigen-presenting B cells by Fas-Fas ligand interaction in an epitope-specific manner.

Suppression by regulatory T cells is now acknowledged to play a key role in the down-regulation of T cell responses to foreign and self Ags. In addition to the naturally occurring CD4(+)CD25(+) population, several subtypes of induced regulatory cells have been reported, but their mechanisms of action remain unclear. Conversely, cytotoxic CD4(+) cells that lyse cells presenting their cognate peptide have been described, but their potential role in immunoregulation remains to be delineated. A CD4(+) T cell line derived from BALB/c mice immunized with peptide 21-35, containing a major T cell epitope of a common allergen, Dermatophagoides pteronyssinus group 2 allergen, was found to lyse the Ag-presenting WEHI cell line via Fas-Fas ligand and only in the presence of the cognate peptide. Cytolytic activity was likewise shown for other T cell lines and occurred even after a single cycle of in vitro stimulation. Moreover, T cells that efficiently lysed WEHI cells were unresponsive to stimulation with their cognate Ag and were dependent on IL-2 for growth and survival, which was reflected in a constitutive expression of CD25 independently of activation status. Proliferating B cells were also killed by the CTLs. By lysing Ag-presenting B cells in an epitope-specific manner, the nonproliferating CTLs were shown to down-regulate the proliferation of bystander T cells. These data demonstrate that cytotoxic CD4(+)CD25(+) T cells that lack proliferation capacities have the potential to down-regulate an immune response by killing Ag-presenting B cells. This could represent an important and specific down-regulatory mechanism of secondary immune responses in vivo.