Genes overexpressed in pancreatic islets of patients with new-onset type 1 diabetes are potential candidates for novel disease-related autoantigens. RT-PCR-based subtractive hybridization was used on islets from a patient who died at the onset of type 1 diabetes, and it identified a type 1 diabetes-related cDNA encoding hepatocarcinoma-intestine-pancreas/pancreatic-associated protein (HIP/PAP). This protein belongs to the family of Reg proteins implicated in islet regeneration; its gene contains a putative interleukin-6 (IL-6) response element. Islets from healthy cadaveric human donors released HIP/PAP protein into the culture medium, and this release was enhanced by the addition of IL-6. The expression pattern of mouse homologues of HIP/PAP was determined in pancreata of prediabetic and diabetic NOD mice. Both groups showed positive immunostaining for HIP/PAP in islets and ductal epithelium. To test whether HIP/PAP is a target of isletdirected autoimmunity, we measured splenic T-cell responses against HIP/PAP in NOD mice. Spontaneous proliferation was detected after 4 weeks. Lymphocytes from islet infiltrates and pancreatic lymph nodes from 7-to 10-week-old NOD mice were used to establish an HIP/PAP-specific I-A g7 -restricted T-cell line, termed WY1, that also responded to mouse islets. WY1 cells homed to islets of NOD-SCID mice and adoptively transferred disease when coinjected with purified CD8 ؉ cells from diabetic NOD mice. Our conclusion was that differential cloning of Reg from islets of a type 1 diabetic patient and the response of Reg to the cytokine IL-6 suggests that HIP/PAP becomes overexpressed in human diabetic islets because of the local inflammatory response. HIP/PAP acts as a T-cell autoantigen in NOD mice. Therefore, autoimmunity to HIP/PAP might create a vicious cycle, accelerating the immune process leading to diabetes. Diabetes 51:339 -346, 2002

The Reg family of proteins has been studied in the context of growth and regeneration in several organs including pancreatic islets. We previously suggested that Reg proteins act as autoantigens in type 1 diabetes, based on evidence that a member of the Reg family (hepatocellular carcinoma intestine pancreas [HIP]/pancreatitis-associated protein [PAP]) was overexpressed in the islets of a patient who died after sudden onset of type 1 diabetes, and that, in NOD mice, Reg-specific T-cells adoptively transferred diabetes. In the current study, we developed antisera to detect individual Reg members in mouse islets and found that RegIII␣ was present in the non-␤-cell portion of the islets, while RegII was predominantly expressed in ␤-cells.

Insulin-producing β cells can partially regenerate in adult pancreatic tissues, both in human and animal models of type 1 diabetes (T1D). Previous studies have shown that treatment with mycobacterial adjuvants such as CFA and bacillus Calmette-Guérin prevents induction and recurrence of T1D in NOD mice with partial recovery of β cell mass. In this study, we investigated factors involved in the regeneration of β cells in the pancreas of NOD mice during diabetes development and after treatment with adjuvants. The Regeneration (Reg) gene family is known to be involved in regeneration of various tissues including β cells. Reg2 expression was found to be upregulated in pancreatic islets both during diabetes development and as a result of adjuvant treatment in diabetic NOD mice and in C57BL/6 mice made diabetic by streptozotocin treatment. The upregulation of Reg2 by adjuvant treatment was independent of signaling through MyD88 and IL-6 because it was not altered in MyD88 or IL-6 knockout mice. We also observed upregulation of Reg2 in the pancreas of diabetic mice undergoing β cell regenerative therapy with exendin-4 or with islet neogenesis-associated protein. Reg2 expression following adjuvant treatment correlated with a reduction in insulitis, an increase in insulin secretion, and an increase in the number of small islets in the pancreas of diabetic NOD mice and with improved glucose tolerance tests in streptozotocin-treated diabetic C57BL/6 mice. In conclusion, adjuvant immunotherapy regulates T1D in diabetic mice and induces Reg2-mediated regeneration of β cells.

Aims/hypothesis The expression of IFNβ in beta cells results in accelerated type 1 diabetes. The REG family of beta cell proliferation factors have been described as autoantigens in autoimmune diabetes. The aim of this study was to determine the effect of IFNβ on Reg expression, and the implications of this in terms of autoimmunity. Methods Reg gene expression was determined in islets from non-obese diabetic (NOD) RIP-HuIFNβ mice by cDNA microarray, quantitative real-time PCR and immunohistochemistry. The effect of IFNβ on Reg1 and Reg2 expression was assessed in the NOD insulinoma cell line NIT-1. IL-6, known to induce Reg expression, was measured in the insulitis microenvironment. Morphological studies were carried out to determine islet enlargement in this model. ResultsReg2 was upregulated in islets from the NOD RIPHuIFNβ mice at the onset of the autoimmune attack. IFNβ upregulates Reg1 and Reg2 genes in NIT-1 cells. The expression of Il6 was increased in islets from transgenic mice and in NIT-1 cells exposed to HuIFNβ. Moreover, islets from transgenic mice were enlarged compared with those from wild-type mice. Conclusions/interpretation Reg overexpression correlates well with the acceleration of diabetes in this model. The upregulation of Reg suggests that islets try to improve hyperglycaemia by regenerating the cells lost in the autoimmune attack. Reg expression is regulated by several factors such as inflammation. Therefore, the overexpression of an IFNβ-induced autoantigen (REG) in the islets during inflammation might contribute to the premature onset of diabetes.

Antigen Ov39, derived from Onchocerca volvulus, cross-reacts on both the T and B cell level with a nonhomologous human retinal antigen, hr44. Lewis rats were immunized to investigate the potential of these antigens to induce eye disease. Histologic and immunohistologic examination of ocular tissues revealed pathologic changes as early as day 12, which included induction or up-regulation of class II and CD68-like antigen on perivascular cells, ramified retinal microglia, dendritiform cells of the iris epithelium, and ciliary epithelium and significant breakdown of anterior and posterior blood-ocular barriers. Extravascular immunoglobulin and staining for CD68-like antigen was detected in the optic nerve after immunization with Ov39. Unrelated structural abnormalities of retina and lens seen in 8% of eyes examined significantly predisposed eyes to the development of Ov39- or hr44-induced pathology. These findings suggest a role for cross-reactive immune responses in the development of ocular onchocerciasis.

SummaryStructural similarities between host self-antigens and infectious organisms may be involved in the expression ofautoimmune reactivity and development of autoimmune disease. The unique eye pathology associated with Onchocerca volvulus infection, particularly the development of posterior segment lesions, may be promoted by such autoreactive responses. Ov39 is a parasitederived antigen that has been shown previously to be antigenically cross-reactive with a 44,000-Mr host ocular component. A clone, designated hr44, was isolated from a cDNA library of human retina by immunoscreen using serum to Ov39. A monoclonal antibody raised to Ov39 also reacted with hr44 and gave evidence for a shared conformational epitope. The primary structure analysis showed that identities between the antigens are limited and confined to small peptides. The cross-reactivity between the antigens appears to involve T cells, since Ov39-specific T cells can be stimulated by hr44, a neural-specific antigen. Based on secondary structure prediction, hr44 has the typical features of a membrane-associated type I antigen with an amino-terminal extracellular domain, mAbs and antisera localized the antigen in the optic nerve, neural retina, retinal pigment epithelium, as well as the epithelial layers of ciliary body and iris.

Abstract5′AMP-activated protein kinase (AMPK) activation occurs under a variety of stress conditions but the role of this enzyme in the promotion or inhibition of stress-induced cell death is unclear. To address this issue, we transformed two different cell lines with shRNA-expressing plasmids, targeting the alpha subunit of AMPK, and verified AMPKα downregulation. The cell lines were then stressed by exposure to medium without glucose (PC12 cells) or with the viral thymidine kinase-specific DNA replication inhibitors: acyclovir, penciclovir and ganciclovir (herpes simplex virus thymidine kinase-expressing Baby Hamster Kidney cells). In non-AMPK-downregulated cells, these stress treatments induced AMPK upregulation and phosphorylation, leaving open the question whether the association of AMPK activation with stress-induced cell death reflects a successful death-promoting or an ineffective death-inhibiting activity. In AMPKα-deficient cells (expressing AMPKα-specific shRNAs or treated with Compound C) exposure to low glucose medium or DNA replication inhibitors led to an enhancement of cell death, indicating that, under the conditions examined, the role of activated AMPK is not to promote, but to protect from or delay stress-induced cell death.

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