Evaluation of proteomic biomarkers associated with circulating microparticles as an effective means to stratify the risk of spontaneous preterm birth

BACKGROUND

The analysis of circulating microparticles in pregnancy is of revolutionary potential because it represents an in vivo biopsy of active gestational tissues.

OBJECTIVE

We hypothesized that circulating microparticle signaling will differ in pregnancies that experience spontaneous preterm birth from those delivering at term and that these differences will be evident many weeks in advance of clinical presentation.

STUDY DESIGN

Utilizing plasma specimens obtained between 10 and 12 weeks' gestation as part of a prospectively collected birth cohort in which pregnancy outcomes are independently validated by 2 board-certified maternal-fetal medicine physicians, 25 singleton cases of spontaneous preterm birth ≤ 34 weeks were matched by maternal age, race, and gestational age of sampling (±2 weeks) with 50 uncomplicated term deliveries. Circulating microparticles from these first-trimester specimens were isolated and analyzed by multiple reaction monitoring mass spectrometry for potential protein biomarkers following previous studies. Markers with robust univariate performance in correlating spontaneous preterm birth were further evaluated for their biological relevance via a combined functional profiling/pathway analysis and for multivariate performance.

RESULTS

Among the 132 proteins evaluated, 62 demonstrated robust power of detecting spontaneous preterm birth in a bootstrap receiver-operating characteristic curve analysis at a false discovery rate of < 20% estimated via label permutation. Differential dependency network analysis identified spontaneous preterm birth-associated coexpression patterns linked to biological processes of inflammation, wound healing, and the coagulation cascade. Linear modeling of spontaneous preterm birth using a multiplex of the candidate biomarkers with a fixed sensitivity of 80% exhibited a specificity of 83% with median area under the curve of 0.89. These results indicate a strong potential of multivariate model development for informative risk stratification.

CONCLUSION

This project has identified functional proteomic factors with associated biological processes that are already unique in their expression profiles at 10-12 weeks among women who go on to deliver spontaneously ≤ 34 weeks. These changes, with further validation, will allow the stratification of patients at risk of spontaneous preterm birth before clinical presentation.

Insulin B chain 9-23 gene transfer to hepatocytes protects from type 1 diabetes by inducing Ag-specific FoxP3+ Tregs

Antigen (Ag)-specific tolerance in type 1 diabetes (T1D) in human has not been achieved yet. Targeting lentiviral vector (LV)-mediated gene expression to hepatocytes induces active tolerance toward the encoded Ag. The insulin B chain 9-23 (InsB9-23) is an immunodominant T cell epitope in nonobese diabetic (NOD) mice. To determine whether auto-Ag gene transfer to hepatocytes induces tolerance and control of T1D, NOD mice were treated with integrase-competent LVs (ICLVs) that selectively target the expression of InsB9-23 to hepatocytes. ICLV treatment induced InsB9-23-specific effector T cells but also FoxP3(+) regulatory T cells (Tregs), which halted islet immune cell infiltration, and protected from T1D. Moreover, ICLV treatment combined with a single suboptimal dose of anti-CD3 monoclonal antibody (mAb) is effective in T1D reversal. Splenocytes from LV.InsB9-23-treated mice, but not from LV.OVA (ovalbumin)-treated control mice, stopped diabetes development, demonstrating that protection is Ag-specific. Depletion of CD4(+)CD25(+)FoxP3(+) T cells led to diabetes progression, indicating that Ag-specific FoxP3(+) Tregs mediate protection. Integrase-defective LVs (IDLVs).InsB9-23, which alleviate the concerns for insertional mutagenesis and support transient transgene expression in hepatocytes, were also efficient in protecting from T1D. These data demonstrate that hepatocyte-targeted auto-Ag gene expression prevents and resolves T1D and that stable integration of the transgene is not required for this protection. Gene transfer to hepatocytes can be used to induce Ag-specific tolerance in autoimmune diseases.

The cellular and molecular mechanisms of immuno-suppression by human type 1 regulatory T cells

The immuno-regulatory mechanisms of IL-10-producing type 1 regulatory T (Tr1) cells have been widely studied over the years. However, several recent discoveries have shed new light on the cellular and molecular mechanisms that human Tr1 cells use to control immune responses and induce tolerance. In this review we outline the well known and newly discovered regulatory properties of human Tr1 cells and provide an in-depth comparison of the known suppressor mechanisms of Tr1 cells with FOXP3⁺ T_reg. We also highlight the role that Tr1 cells play in promoting and maintaining tolerance in autoimmunity, allergy, and transplantation.

Reduced IL-2 expression in NOD mice leads to a temporal increase in CD62Llo FoxP3+ CD4+ T cells with limited suppressor activity

IL-2 plays a critical role in the induction and maintenance of FoxP3-expressing regulatory T cells (FoxP3(+) Tregs). Reduced expression of IL-2 is linked to T-cell-mediated autoimmune diseases such as type 1 diabetes (T1D), in which an imbalance between FoxP3(+) Tregs and pathogenic T effectors exists. We investigated the contribution of IL-2 to dysregulation of FoxP3(+) Tregs by comparing wildtype NOD mice with animals congenic for a C57BL/6-derived disease-resistant Il2 allele and in which T-cell secretion of IL-2 is increased (NOD.B6Idd3). Although NOD mice exhibited a progressive decline in the frequency of CD62L(hi) FoxP3(+) Tregs due to an increase in CD62L(lo) FoxP3(+) Tregs, CD62L(hi) FoxP3(+) Tregs were maintained in the pancreatic lymph nodes and islets of NOD.B6Idd3 mice. Notably, the frequency of proliferating CD62L(hi) FoxP3(+) Tregs was elevated in the islets of NOD.B6Idd3 versus NOD mice. Increasing levels of IL-2 in vivo also resulted in larger numbers of CD62L(hi) FoxP3(+) Tregs in NOD mice. These results demonstrate that IL-2 influences the suppressor activity of the FoxP3(+) Tregs pool by regulating the balance between CD62L(lo) and CD62L(hi) FoxP3(+) Tregs. In NOD mice, reduced IL-2 expression leads to an increase in nonsuppressive CD62L(lo) FoxP3(+) Tregs, which in turn correlates with a pool of CD62L(hi) FoxP3(+) Tregs with limited proliferation.

Inducible adeno-associated virus-mediated IL-2 gene therapy prevents autoimmune diabetes

IL-2 and TGF-β1 play key roles in the immunobiology of Foxp3-expressing CD25(+)CD4(+) T cells (Foxp3(+)Treg). Administration of these cytokines offers an appealing approach to manipulate the Foxp3(+)Treg pool and treat T cell-mediated autoimmunity such as type 1 diabetes. However, efficacy of cytokine treatment is dependent on the mode of application, and the potent pleiotropic effects of cytokines like IL-2 may lead to severe side effects. In the current study, we used a gene therapy-based approach to assess the efficacy of recombinant adeno-associated virus vectors expressing inducible IL-2 or TGF-β1 transgenes to suppress ongoing β cell autoimmunity in NOD mice. Intramuscular vaccination of recombinant adeno-associated virus to 10-wk-old NOD female mice and a subsequent 3 wk induction of IL-2 was sufficient to prevent diabetes and block the progression of insulitis. Protection correlated with an increased frequency of Foxp3(+)Treg in the periphery as well as in the draining pancreatic lymph nodes and islets. IL-2 induced a shift in the ratio favoring Foxp3(+)Treg versus IFN-γ-expressing T cells infiltrating the islets. Induction of IL-2 had no systemic effect on the frequency or activational status of T cells and NK cells. Induction of TGF-β1 had no effect on the Foxp3(+)Treg pool or the progression of β cell autoimmunity despite induced systemic levels of activated TGF-β1 that were comparable to IL-2. These results demonstrate that inducible IL-2 gene therapy is an effective and safe approach to manipulate Foxp3(+)Treg and suppress T cell-mediated autoimmunity and that under the conditions employed, IL-2 is more potent than TGF-β1.

Immunotherapy for the Prevention and Treatment of Type 1 Diabetes

A major effort has been on-going to develop immunotherapies to prevent and/or treat type 1 diabetes (T1D). This autoimmune disease is characterized by the selective loss of the insulin-producing beta cells via the cumulative effects of autoantigen-specific CD4(+) and CD8(+) T cells, autoantibodies, and activated antigen-presenting cells. To be applicable in a clinical setting, immunotherapies must suppress established beta-cell autoimmunity. Preclinical studies and recent clinical findings suggest that antigen-specific and systemic-based strategies can be effective in this regard. However, either approach alone may not be sufficient to block the diabetogenic response and establish long-term protection in the clinic. In this review, we will discuss the importance of both strategies and how a combinatorial approach to treat T1D is appealing.

Gene gun-mediated DNA vaccination enhances antigen-specific immunotherapy at a late preclinical stage of type 1 diabetes in nonobese diabetic mice

Type 1 diabetes (T1D) is characterized by the T cell mediated destruction of the insulin-producing beta cells. Antigen-specific immunotherapies are used to selectively tolerize beta cell-specific pathogenic T cells either directly, or indirectly through the induction of immunoregulatory T cells. A key concern of antigen-specific immunotherapy is exacerbating autoimmunity. We compared the T cell reactivity and efficacy induced by plasmid DNA (pDNA) encoding glutamic acid decarboxylase 65 (GAD65) administered via intramuscular versus gene gun vaccination in NOD mice at a late preclinical stage of T1D. Whereas intramuscular injection of pGAD65 promoted a predominant type 1 CD4(+) T cell response and failed to suppress ongoing beta cell autoimmunity, gene gun vaccination preferentially induced IL-4 secreting CD4(+) T cells and significantly delayed the onset of diabetes. These findings demonstrate that gene gun delivery of autoantigen-encoding pDNA preferentially elicits immunoregulatory T cells and offers a safe, effective mode of pDNA vaccination for the treatment of T1D and other autoimmune diseases.

The type and frequency of immunoregulatory CD4+ T-cells govern the efficacy of antigen-specific immunotherapy in nonobese diabetic mice

Antigen-specific immunotherapy, an approach to selectively block autoimmune diabetes, generally declines in nonobese diabetic (NOD) mice as disease progresses. To define the parameters influencing the efficacy of antigen-specific immunotherapy once diabetes is established, plasmid DNA (pDNA) vaccination was used to suppress autoimmune-mediated destruction of syngeneic islet grafts in diabetic NOD recipients. pDNAs encoding a glutamic acid decarboxylase 65 (GAD65)-Ig molecule (pGAD65), interleukin (IL)-4 (pIL4), and IL-10 (pIL10) significantly delayed the onset of recurrent diabetes compared with pGAD65+pIL10-vaccinated recipients. Despite differences in efficacy, a similar frequency of GAD65-specific CD4(+) T-cells secreting IL-4, IL-10, or interferon-gamma were detected in mice treated with pGAD65+pIL4+pIL10 and pGAD65+pIL10. However, the frequency of FoxP3-expressing CD4(+)CD25(+)CD62L(hi) T-cells was increased in the renal and pancreatic lymph nodes of diabetic recipients vaccinated with pGAD65+pIL4+pIL10. These immunoregulatory CD4(+)CD25(+) T-cells (CD4(+)CD25(+) Treg) exhibited enhanced in vivo and in vitro suppressor activity that partially was transforming growth factor-beta dependent. Furthermore, duration of islet graft protection in pGAD65+pIL4+pIL10-vaccinated diabetic recipients correlated with the persistence of CD4(+)CD25(+) Treg. These data demonstrate that the frequency and maintenance of FoxP3-expressing CD4(+)CD25(+) Treg influence antigen-induced suppression of ongoing beta-cell autoimmunity in diabetic recipients.

Identical beta cell-specific CD8(+) T cell clonotypes typically reside in both peripheral blood lymphocyte and pancreatic islets

A major issue regarding T cell responses in autoimmunity is how the repertoire compares between the periphery and target organ. In type 1 diabetes, the status of at-risk or diabetic individuals can be monitored by measuring beta cell-specific T cells isolated from PBL, but whether these T cells accurately reflect the repertoire residing in the pancreatic islets is unclear. The TCR repertoire of disease-relevant, tetramer-sorted CD8(+) T cells was examined at the single-cell level in PBL, pancreatic lymph nodes (PLN), and the islets of individual NOD mice. CDR3alpha and CDR3beta sequences demonstrated that the same repertoire of T cells in PBL was detected in the islets and PLN, although the frequency of specific clonotypes varied. Albeit infrequent, clonotypes that were prevalent in the islets but not found in PBL were also detected. beta cell Ag immunization expanded immunodominant PBL clonotypes present in the islets and PLN. These results show that insight into repertoire profiles of islet-infiltrating T cells can be obtained from PBL.

Glucose-responsive expression of the human insulin promoter in HepG2 human hepatoma cells

The concept of insulin production afforded by hepatic gene therapy retains promise as a potential therapy for type 1 diabetes, but the approach has been limited by the need for strict transgene regulation in response to fluctuating levels of both glucose and insulin. Furthermore, while hepatocytes contain various glucose-responsive elements, they lack the appropriate regulated secretory system necessary for insulin release, thereby necessitating the requirement for transcriptional regulation of hepatic insulin production under the direction of a glucose-responsive promoter. To address this, we have evaluated several glucose-responsive promoters that may be used successfully for hepatic insulin production via recombinant adeno-associated virus (rAAV) therapy. Our results suggest that the human insulin promoter represents a strong candidate as a robust, glucose-responsive promoter for regulated hepatic insulin production.

Systemic overexpression of IL-10 induces CD4+CD25+ cell populations in vivo and ameliorates type 1 diabetes in nonobese diabetic mice in a dose-dependent fashion

Early systemic treatment of nonobese diabetic mice with high doses of recombinant adeno-associated virus (rAAV) vector expressing murine IL-10 prevents type 1 diabetes. To determine the therapeutic parameters and immunological mechanisms underlying this observation, female nonobese diabetic mice at 4, 8, and 12 wk of age were given a single i.m. injection of rAAV-murine IL-10 (10(4), 10(6), 10(8), and 10(9) infectious units (IU)), rAAV-vector expressing truncated murine IL-10 fragment (10(9) IU), or saline. Transduction with rAAV-IL-10 at 10(9) IU completely prevented diabetes in all animals injected at all time points, including, surprisingly, 12-wk-old animals. Treatment with 10(8) IU provided no protection in the 12-wk-old injected mice, partial prevention in 8-wk-old mice, and full protection in all animals injected at 4 wk of age. All other treatment groups developed diabetes at a similar rate. The rAAV-IL-10 therapy attenuated pancreatic insulitis, decreased MHC II expression on CD11b+ cells, increased the population of CD11b+ cells, and modulated insulin autoantibody production. Interestingly, rAAV-IL-10 therapy dramatically increased the percentage of CD4+CD25+ regulatory T cells. Adoptive transfer studies suggest that rAAV-IL-10 treatment alters the capacity of splenocytes to impart type 1 diabetes in recipient animals. This study indicates the potential for immunomodulatory gene therapy to prevent autoimmune diseases, including type 1 diabetes, and implicates IL-10 as a molecule capable of increasing the percentages of regulatory cells in vivo.