Biomaterials-based nanoparticles conjugated to regulatory T cells provide a modular system for localized delivery of pharmacotherapeutic agents.

Type 1 diabetes (T1D) presents with two therapeutic challenges: the need to correct underlying autoimmunity and restore ß-cell mass. We harnessed the unique capacity of regulatory T cells (Tregs) and the T cell receptor (TCR) to direct tolerance induction along with tissue-localized delivery of therapeutic agents to restore endogenous ß-cell function. Specifically, we designed a combinatorial therapy involving biomaterials-based poly(lactic-co-glycolic acid) nanoparticles co-loaded with the Treg growth factor, IL-2, and the ß-cell regenerative agent, harmine (a tyrosine-regulated kinase 1A [DYRK1A] inhibitor), conjugated to the surface of Tregs. We observed continuous elution of IL-2 and harmine from nanoparticles for at least 7 days in vitro. When conjugated to primary human Tregs, IL-2 nanoparticles provided sufficient IL-2 receptor signaling to support STAT5 phosphorylation for sustained phenotypic stability and viability in culture. Inclusion of poly-L-lysine (PLL) during nanoparticle-cell coupling dramatically increased conjugation efficiency, providing sufficient IL-2 to support in vitro proliferation of IL-2-dependent CTLL-2 cells and primary murine Tregs. In 12-week-old female non-obese diabetic mice, adoptive transfer of IL-2/harmine nanoparticle-conjugated NOD.BDC2.5 Tregs, which express an islet antigen-specific TCR, significantly prevented diabetes demonstrating preserved in vivo viability. These data provide the preclinical basis to develop a biomaterials-optimized cellular therapy to restore immune tolerance and promote ß-cell proliferation in T1D through receptor-targeted drug delivery within pancreatic islets.

Effects of type 1 diabetes-associated IFIH1 polymorphisms on MDA5 function and expression.

Recent evidence has highlighted the role of the innate immune system in type 1 diabetes (T1D) pathogenesis. Specifically, aberrant activation of the interferon response prior to seroconversion of T1D-associated autoantibodies supports a role for the interferon response as a precipitating event toward activation of autoimmunity. Melanoma differentiation-associated protein 5 (MDA5), encoded by IFIH1, mediates the innate immune system's interferon response to certain viral species that form double-stranded RNA (dsRNA), the MDA5 ligand, during their life cycle. Extensive research has associated single nucleotide polymorphisms (SNPs) within the coding region of IFIH1 with T1D. This review discusses the different risk and protective IFIH1 alleles in the context of recent structural and functional analysis that relate to MDA5 regulation of interferon responses. These studies have provided a functional hypothesis for IFIH1 T1D-associated SNPs' effects on MDA5-mediated interferon responses as well as supporting the genome-wide association (GWA) studies that first associated IFIH1 with T1D.

Elevated corticosterone in the dorsal hindbrain increases plasma norepinephrine and neuropeptide Y, and recruits a vasopressin response to stress.

Repeated stress and chronically elevated glucocorticoids cause exaggerated cardiovascular responses to novel stress, elevations in baseline blood pressure, and increased risk for cardiovascular disease. We hypothesized that elevated corticosterone (Cort) within the dorsal hindbrain (DHB) would: 1) enhance arterial pressure and neuroendocrine responses to novel and repeated restraint stress, 2) increase c-Fos expression in regions of the brain involved in sympathetic stimulation during stress, and 3) recruit a vasopressin-mediated blood pressure response to acute stress. Small pellets made of 10% Cort were implanted on the surface of the DHB in male Sprague-Dawley rats. Blood pressure was measured by radiotelemetry. Cort concentration was increased in the DHB in Cort-treated compared with Sham-treated rats (60 ± 15 vs. 14 ± 2 ng Cort/g of tissue, P < 0.05). DHB Cort significantly increased the integrated arterial pressure response to 60 min of restraint stress on days 6, 13, and 14 following pellet implantation (e.g., 731 ± 170 vs. 1,204 ± 68 mmHg/60 min in Sham- vs. Cort-treated rats, day 6, P < 0.05). Cort also increased baseline blood pressure by day 15 (99 ± 2 vs. 108 ± 3 mmHg for Sham- vs. Cort-treated rats, P < 0.05) and elevated baseline plasma norepinephrine and neuropeptide Y concentrations. Cort significantly enhanced stress-induced c-Fos expression in vasopressin-expressing neurons in the paraventricular nucleus of the hypothalamus, and blockade of peripheral vasopressin V1 receptors attenuated the effect of DHB Cort to enhance the blood pressure response to restraint. These data indicate that glucocorticoids act within the DHB to produce some of the adverse cardiovascular consequences of chronic stress, in part, by a peripheral vasopressin-dependent mechanism.

Anti-CD3 antibody treatment induces hypoglycemia and super tolerance to glucose challenge in mice through enhancing glucose consumption by activated lymphocytes.

Anti-CD3 antibody has been employed for various immune-mediated disorders. However, whether anti-CD3 administration leads to rapid metabolic alternation has not been well investigated. In the current study, we studied how anti-CD3 treatment affected blood glucose levels in mice. We found that anti-CD3 treatment induced immediate reduction of blood glucose after administration. Furthermore, a single dose of anti-CD3 treatment corrected hyperglycemia in all nonobese diabetic mice with recently diagnosed diabetes. This glucose-lowering effect was not attributable to major T cell produced cytokines. Of interest, when tested in a normal strain of mice (C57BL/6), the serum levels of C-peptide in anti-CD3 treated animals were significantly lower than control mice. Paradoxically, anti-CD3 treated animals were highly tolerant to exogenous glucose challenge. Additionally, we found that anti-CD3 treatment significantly induced activation of T and B cells in vitro and in vivo. Further studies demonstrated that anti-CD3 treatment lowered the glucose levels in T cell culture media and increased the intracellular transportation of 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2 deoxyglucose (2-NBDG) particularly in activated T and B cells. In addition, injection of anti-CD3 antibodies induced enhanced levels of Glut1 expression in spleen cells. This study suggests that anti-CD3 therapy-induced hypoglycemia likely results from increased glucose transportation and consumption by the activated lymphocytes.

Anti-thymocyte globulin (ATG) differentially depletes naïve and memory T cells and permits memory-type regulatory T cells in nonobese diabetic mice.

BACKGROUND: ATG has been employed to deplete T cells in several immune-mediated conditions. However, whether ATG administration affects naïve and memory T cell differently is largely unknown. THE CONTEXT AND PURPOSE OF THE STUDY: In this study, we assessed how murine ATG therapy affected T cell subsets in NOD mice, based on their regulatory and naïve or memory phenotype, as well as its influence on antigen-specific immune responses. RESULTS: Peripheral blood CD4+ and CD8+ T cells post-ATG therapy declined to their lowest levels at day 3, while CD4+ T cells returned to normal levels more rapidly than CD8+ T cells. ATG therapy failed to eliminate antigen-primed T cells. CD4+ T cell responses post-ATG therapy skewed to T helper type 2 (Th2) and possibly IL-10-producing T regulatory type 1 (Tr1) cells. Intriguingly, Foxp3+ regulatory T cells (Tregs) were less sensitive to ATG depletion and remained at higher levels following in vivo recovery compared to controls. Of note, the frequency of Foxp3+ Tregs with memory T cell phenotype was significantly increased in ATG-treated animals. CONCLUSION: ATG therapy may modulate antigen-specific immune responses through inducing memory-like regulatory T cells as well as other protective T cells such as Th2 and IL-10-producing Tr1 cells.

Administration of recombinant human thioredoxin-1 significantly delays and prevents autoimmune diabetes in nonobese diabetic mice through modulation of autoimmunity.

BACKGROUND: Thioredoxin as a biological antioxidant plays an important role in regulating the redox system. The administration of recombinant thioredoxin has been demonstrated to be anti-inflammatory. In this study, the effect of recombinant human thioredoxin-1 (rhTrx-1) in preventing type 1 diabetes (T1D) in nonobese diabetic (NOD) mice was evaluated. METHODS: Eight-week-old NOD mice were treated with intravenous injection of rhTrx-1 (5 µg/mouse/day) for 5 weeks (5 days a week), followed by every other day for additional 5 weeks. Diabetes onset was monitored twice a week. Pancreatic histology and ß-cell mass were examined by hematoxylin and eosin (H&E) and insulin immunohistochemistry staining, respectively. Adoptive transfer experiments were executed to assess autoimmune T cells modulated by rhTrx treatment. RESULTS: The intravenous administration of rhTrx-1 significantly delayed and prevented T1D in NOD mice. The histology data showed that rhTrx-1 treatment markedly reduced insulitic lesions and significantly preserved insulin-producing ß cells. Adoptive transfer of spleen cells from rhTrx-1-treated mice into nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice significantly reduced the diabetes onset than transfer of those from phosphate-buffered saline-treated mice. Adoptive co-transfer experiments demonstrated that spleen cells from rhTrx-1-treated mice significantly delayed diabetes induced by the co-transferred diabetogenic spleen cells from the new-onset diabetic mice. CONCLUSIONS: Antioxidant rhTrx-1 effectively prevents T1D which may be attributed to its activity to modulate autoimmunity.