Acute shock induced by antigen vaccination in NOD mice

Soluble antigen arrays provide increased efficacy and safety over free peptides for tolerogenic immunotherapy

Autoantigen-specific immunotherapy using peptides offers a more targeted approach to treat autoimmune diseases, but clinical implementation has been challenging. We previously showed that multivalent delivery of peptides as soluble antigen arrays (SAgAs) efficiently protects against spontaneous autoimmune diabetes in the non-obese diabetic (NOD) mouse model. Here, we compared the efficacy, safety, and mechanisms of action of SAgAs versus free peptides. SAgAs, but not their corresponding free peptides at equivalent doses, efficiently prevented the development of diabetes. SAgAs increased the frequency of regulatory T cells among peptide-specific T cells or induce their anergy/exhaustion or deletion, depending on the type of SAgA used (hydrolysable (hSAgA) and non-hydrolysable 'click' SAgA (cSAgA)) and duration of treatment, whereas their corresponding free peptides induced a more effector phenotype following delayed clonal expansion. Over time, the peptides induced an IgE-independent anaphylactic reaction, the incidence of which was significantly delayed when peptides were in SAgA form rather than in free form. Moreover, the N-terminal modification of peptides with aminooxy or alkyne linkers, which was needed for grafting onto hyaluronic acid to make hSAgA or cSAgA variants, respectively, influenced their stimulatory potency and safety, with alkyne-functionalized peptides being more potent and less anaphylactogenic than aminooxy-functionalized peptides. Immunologic anaphylaxis occurred in NOD mice in a dose-dependent manner but not in C57BL/6 or BALB/c mice; however, its incidence did not correlate with the level of anti-peptide antibodies. We provide evidence that SAgAs significantly improve the efficacy of peptides to induce tolerance and prevent autoimmune diabetes while at the same time reducing their anaphylactogenic potential.

Soluble antigen arrays improve the efficacy and safety of peptide-based tolerogenic immunotherapy

Autoantigen-specific immunotherapy using peptides offers a more targeted approach to treat autoimmune diseases, but the limited in vivo stability and uptake of peptides impedes clinical implementation. We previously showed that multivalent delivery of peptides as soluble antigen arrays (SAgAs) efficiently protects against spontaneous autoimmune diabetes in the non-obese diabetic (NOD) mouse model. Here, we compared the efficacy, safety, and mechanisms of action of SAgAs versus free peptides. SAgAs, but not their corresponding free peptides at equivalent doses, efficiently prevented the development of diabetes. SAgAs increased the frequency of regulatory T cells among peptide-specific T cells or induce their anergy/exhaustion or deletion, depending on the type of SAgA (hydrolysable (hSAgA) and non-hydrolysable 'click' SAgA (cSAgA)) and duration of treatment, whereas their corresponding free peptides induced a more effector phenotype following delayed clonal expansion. Moreover, the N-terminal modification of peptides with aminooxy or alkyne linkers, which was needed for grafting onto hyaluronic acid to make hSAgA or cSAgA variants, respectively, influenced their stimulatory potency and safety, with alkyne-functionalized peptides being more potent and less anaphylactogenic than aminooxy-functionalized peptides. Both SAgA variants significantly delayed anaphylaxis compared to their respective free peptides. The anaphylaxis, which occurred in NOD mice but not in C57BL/6 mice, was dose-dependent but did not correlate with the production of IgG1 or IgE against the peptides. We provide evidence that SAgAs significantly improve the efficacy and safety of peptide-based immunotherapy.

Knockdown of IFNAR2 reduces the inflammatory response in mouse model of type 1 diabetes

BACKGROUND

and Purpose: To investigate the biological role of interferon α/β receptor 2 (IFNAR2) in type 1 diabetes (T1D).

METHODS

First, IFNAR2 mRNA and protein expression levels in serum of T1D patients and healthy controls were detected by RT-qPCR and Western blot. For experimental studies, 80 male C57BL/6 mice were randomly divided into 4 groups with 20 mice in each group: the control group, the T1D group, the T1D + ad-con group and the T1D + ad-si-IFNAR2 group. The T1D mouse model was generated by multiple intraperitoneal injections of small doses of streptozotocin (STZ). Body weight and blood glucose levels were measured weekly until 6 weeks. After 6 weeks, all mice were sacrificed and the levels of insulin (Ins), tumor necrosis factor α (TNF-α), interleukin 4 (IL-4), IL-6, and type I interferon γ (IFN-γ), IFNAR2 protein expression, the number of dendritic cells (DCs), and changes in islet β cells were assessed.

RESULTS

IFNAR2 mRNA and protein expression levels in serum of T1D patients were significantly higher than those in healthy controls (P < 0.05). Furthermore, IFNAR2 protein expression, number of DCs, and IFNAR2 mRNA, blood glucose, TNF-α, and IFN-γ levels were significantly upregulated in T1D mice compared with the control group (P < 0.05), while weight, and Ins, IL-6, and IL-4 levels were decreased (P < 0.05). However, knockdown of IFNAR2 reversed these trends. There was no significant difference in markers between the T1D + ad-con group and the T1D group (P > 0.05).

CONCLUSIONS

Knockdown of IFNAR2 reduced the inflammatory response and improved islet function of T1D mice.

Soluble Antigen Arrays Efficiently Deliver Peptides and Arrest Spontaneous Autoimmune Diabetes

Antigen-specific immunotherapy (ASIT) offers a targeted treatment of autoimmune diseases that selectively inhibits autoreactive lymphocytes, but there remains an unmet need for approaches that address the limited clinical efficacy of ASIT. Soluble antigen arrays (SAgAs) deliver antigenic peptides or proteins in multivalent form, attached to a hyaluronic acid backbone using either hydrolysable linkers (hSAgAs) or stable click chemistry linkers (cSAgAs). They were evaluated for the ability to block spontaneous development of disease in a nonobese diabetic mouse model of type 1 diabetes (T1D). Two peptides, a hybrid insulin peptide and a mimotope, efficiently prevented the onset of T1D when delivered in combination as SAgAs, but not individually. Relative to free peptides administered at equimolar dose, SAgAs (particularly cSAgAs) enabled a more effective engagement of antigen-specific T cells with greater persistence and induction of tolerance markers, such as CD73, interleukin-10, programmed death-1, and KLRG-1. Anaphylaxis caused by free peptides was attenuated using hSAgA and obviated using cSAgA platforms. Despite similarities, the two peptides elicited largely nonoverlapping and possibly complementary responses among endogenous T cells in treated mice. Thus, SAgAs offer a novel and promising ASIT platform superior to free peptides in inducing tolerance while mitigating risks of anaphylaxis for the treatment of T1D.

Contribution of both B-cell intrinsic alterations as well as non-hematopoietic-derived factors in the enhanced immune response of the NOD mouse

The underlying cellular and molecular mechanism for the development of Type 1 diabetes is still to be fully revealed. We have previously demonstrated that the NOD mouse, a model for Type 1 diabetes, display a prolonged and enhanced immune response to both self and non-self-antigens. The molecular explanation for this defect however, has not been determined. In this study we immunized NOD and C57BL/6 (B6) with the conventional antigen i.e. hen egg lysozyme (HEL) and analyzed B cell activation, germinal center reaction and antibody clearance. Corroborating our previous observations NOD mice responded robustly to a single immunization of HEL. Immunofluorescence analysis of the spleen revealed an increased number of germinal centers in unimmunized NOD compared to B6. However, post immunization germinal center numbers were similar in NOD and B6. NOD mice showed lower response to BCR stimulation with anti-IgM, in particular at lower concentrations of anti-IgM. Antibody clearance in vivo did not differ between the strains. To determine the cell type that is responsible for the prolonged and enhance immune response, we reconstituted NOD-RAGs with cells from primed donors in different combinations. NOD B cells were required to reproduce the phenotype; however the non-lymphoid compartment of NOD origin also played a role. Based on our results we propose that preexisting GCs in the NOD promote the robust response and alteration in the BCR signaling could promote survival of stimulated cells. Overall, this mechanism could in turn also contribute to the activation and maintenance of autoreactive B cells in the NOD mouse.

YY-1224, a terpene trilactone-strengthened Ginkgo biloba, attenuates neurodegenerative changes induced by β-amyloid (1-42) or double transgenic overexpression of APP and PS1 via inhibition of cyclooxygenase-2

BACKGROUND

Ginkgo biloba has been reported to possess free radical-scavenging antioxidant activity and anti-inflammatory properties. In our pilot study, YY-1224, a terpene trilactone-strengthened extract of G. biloba, showed anti-inflammatory, neurotrophic, and antioxidant effects.

RESULTS

We investigated the pharmacological potential of YY-1224 in β-amyloid (Aβ) (1-42)-induced memory impairment using cyclooxygenase-2 (COX-2) knockout (-/-) and APPswe/PS1dE9 transgenic (APP/PS1 Tg) mice. Repeated treatment with YY-1224 significantly attenuated Aβ (1-42)-induced memory impairment in COX-2 (+/+) mice, but not in COX-2 (-/-) mice. YY-1224 significantly attenuated Aβ (1-42)-induced upregulation of platelet-activating factor (PAF) receptor gene expression, reactive oxygen species, and pro-inflammatory factors. In addition, YY-1224 significantly inhibited Aβ (1-42)-induced downregulation of PAF-acetylhydrolase-1 (PAF-AH-1) and peroxisome proliferator-activated receptor γ (PPARγ) gene expression. These changes were more pronounced in COX-2 (+/+) mice than in COX-2 (-/-) mice. YY-1224 significantly attenuated learning impairment, Aβ deposition, and pro-inflammatory microglial activation in APP/PS1 Tg mice, whereas it significantly enhanced PAF-AH and PPARγ expression. A preferential COX-2 inhibitor, meloxicam, did not affect the pharmacological activity by YY-1224, suggesting that the COX-2 gene is a critical mediator of the neuroprotective effects of YY-1224. The protective activity of YY-1224 appeared to be more efficacious than a standard G. biloba extract (Gb) against Aβ insult.

CONCLUSIONS

Our results suggest that the protective effects of YY-1224 against Aβ toxicity may be associated with its PAF antagonistic- and PPARγ agonistic-potential as well as inhibition of the Aβ-mediated pro-inflammatory switch of microglia phenotypes through suppression of COX-2 expression.

Splenocyte proliferation and anaphylaxis induced by BSA challenge in a D-galactose-induced aging mouse model

We previously found a cross-reactive autoantibody that bound to bovine serum albumin generated in a D-galactose-induced aging mouse model. Also, we confirmed that other reducing sugars (glucose and fructose) could induce the formation of autoantibody, and only following subcutaneous injection, not oral or intraperitoneal administration. Mice that had never been exposed to bovine serum albumin produced an anti-bovine serum albumin autoantibody following repeated subcutaneous injection of D-galactose (D-gal). In this study, we investigated the involvement of the adaptive immune system in the production of this autoantibody. In particular, we examined bovine serum albumin-induced splenocyte proliferation and bovine serum albumin-induced active cutaneous and systemic anaphylaxis in D-gal-treated mice. We find our results particularly interesting: bovine serum albumin stimulates splenocyte proliferation and induces both active cutaneous and systemic anaphylaxis in D-gal-treated mice. In summary, our results suggest that adaptive immune response participates in the autoantibody formation against bovine serum albumin in D-gal-treated mice.

Destabilization of peptide:MHC interaction induces IL-2 resistant anergy in diabetogenic T cells

Autoreactive T cells are responsible for inducing several autoimmune diseases, including type 1 diabetes. We have developed a strategy to induce unresponsiveness in these cells by destabilizing the peptide:MHC ligand recognized by the T cell receptor. By introducing amino acid substitutions into the immunogenic peptide at residues that bind to the MHC, the half life of the peptide:MHC complex is severely reduced, thereby resulting in abortive T cell activation and anergy. By treating a monoclonal diabetogenic T cell population with an MHC variant peptide, the cells are rendered unresponsive to the wild type ligand, as measured by both proliferation and IL-2 production. Stimulation of T cells with MHC variant peptides results in minimal Erk1/2 phosphorylation or cell division. Variant peptide stimulation effectively initiates a signaling program dominated by sustained tyrosine phosphatase activity, including elevated SHP-1 activity. These negative signaling events result in an anergic phenotype in which the T cells are not competent to signal through the IL-2 receptor, as evidenced by a lack of phospho-Stat5 upregulation and proliferation, despite high expression of the IL-2 receptor. This unique negative signaling profile provides a novel means to shut down the anti-self response.

The current state of play of rodent models to study the role of vitamin D in UV-induced immunomodulation

Ultraviolet radiation (UVR) from sunlight is immunomodulatory and the main source of vitamin D for humans. Vitamin D can also regulate adaptive immunity, through mechanisms that involve the induction or activation of regulatory T cells. Similar mechanisms have also been proposed for the induction of regulatory T cells after skin exposure to UVR. Here we discuss the converging and diverging immunoregulatory pathways of UVR and vitamin D, including the molecular pathways for regulatory T cell induction, non-genomic pathways regulated by vitamin D, antimicrobial peptides, skin integrity and potential interactions between vitamin D and other UVR-induced mediators. We then discuss possible in vivo approaches that could be used to demonstrate a direct (or otherwise) role for vitamin D in mediating the immunosuppressive effects of UVR such as the use of dietary vitamin D restriction to induce vitamin D deficiency, gene knockout mice or drugs to block enzymes of vitamin D metabolism. We end with discussion of the epigenetic effects of vitamin D and UVR for immunosuppression.

Impact of family history of diabetes on β-cell function and insulin resistance among Chinese with normal glucose tolerance

OBJECTIVE

This study investigated the impact of family history of diabetes (FHD) on β-cell function among Chinese with normal glucose tolerance.

RESEARCH DESIGN AND METHODS

A multistage, stratified, cluster random sampling method was used to select a provincially representative sample from Fujian Province. Eventually, a total of 1,183 subjects were entered into the analysis. Several indexes were used to assess the function of β cells, including homeostasis model assessment (HOMA) of insulin resistance (IR), HOMA of β cells, insulinogenic index (IGI), and disposition index.

RESULTS

Overweight, increased body mass index, higher low-density lipoprotein cholesterol, and higher total cholesterol (TC) were the dominant features of positive FHD (FHD(+)). The FHD(+) subjects had lower insulin sensitivity (P<0.05). FHD(+) subjects showed higher risk of IR after adjusting for other risk factors (odds ratio 1.523 [1.272-2.009]). However, there was no significant difference in insulin secretion between the two groups. With the use of the multiple linear regression model, waist circumference (WC) and triglycerides (TGs) were found to be independent risk factors of the decline of insulin sensitivity in FHD(+) subjects, and insulin sensitivity declined significantly (P<0.05) with the increase of WC and TGs. In addition, the offspring of fathers with diabetes (PT2D) were much older and had higher TC than those of mothers with diabetes (MT2D). After adjusting for gender of the parents, there was no difference between MT2D and PT2D on insulin sensitivity.

CONCLUSIONS

Inheritance if diabetes is associated with the decline of insulin sensitivity. In addition, insulin sensitivity declined with increasing WC and TG in FHD(+) subjects.

Human alpha 1-antitrypsin therapy induces fatal anaphylaxis in non-obese diabetic mice

Previous studies have shown that human alpha-1 antitrypsin (hAAT) gene delivery prevents type 1 diabetes (T1D) in non-obese diabetic (NOD) mice. Furthermore, hAAT protein administration prolongs acceptance of islet allografts. Therefore, we evaluated the use of purified hAAT protein therapy to prevent T1D in NOD mice. Female NOD, non-obese resistant (NOR), Balb/c and C57BL/6 mice were injected intraperitoneally with vehicle alone or vehicle containing hAAT, human albumin or mouse albumin (or mg/injection/mouse; 2x/week). Preparations of clinical-grade hAAT included API(R), Aralast, Prolastin and Zemaira. Surprisingly, hAAT administration was associated with a high rate of fatal anaphylaxis. In studies seeking T1D prevention at 4 weeks of age, 100% mice died after six injections of hAAT. When administrated at 8-10 weeks of age, most (80-100%) NOD mice died following the fourth injection of hAAT, while 0% of Balb/c and C57BL/6 mice and 10% of NOR mice died. Interestingly, repeated injections of human albumin, but not mouse albumin, also induced sudden death in NOD mice. Antibodies to hAAT were induced 2-3 weeks after hAAT administration and death was prevented by treatment with anti-platelet-activating factor along with anti-histamine. In studies of disease reversal in NOD mice, using the four pharmaceutical grade formulations of hAAT, anaphylactic deaths were observed with all hAAT preparations. The propensity for fatal anaphylaxis following antigenic administration appears to be NOD- but not hAAT-specific. The susceptibility of NOD mice to hypersensitivity provides a significant limitation for testing of hAAT. Development of strategies to avoid this unwanted response is required to use this promising therapeutic agent for T1D.

Comparison of antibody- and cell-mediated immune responses after intramuscular hepatitis C immunizations of BALB/c mice

Current treatments for hepatitis C infection have limited efficacy, and there is no vaccine available. The goal of this study was to compare the immune response to several immunization combinations against hepatitis C virus (HCV). Six groups of mice were immunized at weeks 0, 4, and 8 with different combinations of a candidate HCV vaccine consisting of 100 microg recombinant HCV core/E1/E2 (rHCV) DNA plasmid and/or 25 microg rHCV polyprotein and 50 microL Montanide ISA- 51. Four weeks after the last injection, all groups of mice were sacrificed and blood samples and spleens were collected for measuring the levels of specific HCV antibodies (total IgG, IgG1, and IgG2a). Cell proliferation and intracellular interferon-gamma were also measured. Among the groups of immunized mice, only the mice immunized with rHCV DNA plasmid, rHCV polyprotein, and montanide (group D) and mice immunized with rHCV polyprotein and montanide (group F) demonstrated a significant increase in the total IgG titer after immunization. IgG1 was the predominant antibody detected in both groups D and F. No IgG2a was detected in any of the groups. Proliferation assays demonstrated that splenocytes from group D and group C (rHCV DNA primed/rHCV polyprotein boost) developed significant anti-HCV proliferative responses. The combination of an rHCV DNA plasmid, rHCV polyprotein, and montanide induced a high antibody titer with a predominance of IgG1 antibodies and recognized the major neutralization epitopes in HVR1. In contrast, group C did not show an increase in anti-HCV antibodies, but did show a proliferative response.

Co-delivery of pro-apoptotic BAX with a DNA vaccine recruits dendritic cells and promotes efficacy of autoimmune diabetes prevention in mice

Genetic vaccines encoding pancreatic beta cell antigens can prevent autoimmune (type 1) diabetes when delivered into murine model systems, but there is a need to improve their efficacy. Here, we investigated the effects of intramuscular delivery of DNA coding for the pro-apoptotic protein BAX together with an intracellular or a secreted form of the beta cell antigen glutamic acid decarboxylase (GAD) on diabetes onset and immune responses in non-obese diabetic (NOD) mice. We hypothesized that induction of apoptosis in vaccine-containing cells could lead to GAD tolerance and disease suppression. Remarkably, monitoring of spontaneous diabetes onset indicated that only delivery of DNA coding for secreted GAD and BAX resulted in significant prevention of the disease. Using GFP as a model plasmid-encoded antigen revealed that co-delivery of BAX resulted in the recruitment of GFP-containing dendritic cells (DCs) in the draining lymph nodes and spleen of NOD mice. Furthermore, data indicated that subcellular localization of GAD had an effect on both the number and function of antigen presenting cells (APCs) recruited by BAX as well as on IFN-gamma secretion, and that diabetes suppression was unlikely to be caused by increased T helper 2 (Th2)-like activity. Our results indicate that, under certain conditions, co-delivery of DNA encoding BAX can improve the efficacy of genetic vaccination for prevention of pathogenic autoimmunity via a mechanism likely to involve modulation of antigen presenting cell function. In addition, our data also suggest that properties associated with subcellular localization of an antigen in apoptotic cells can have a significant effect on induced immune responses.