Glucagon-Like Peptide-1 Protects Human Islets against Cytokine-Mediated β-Cell Dysfunction and Death: A Proteomic Study of the Pathways Involved

Glucagon-like peptide-1 (GLP-1) has been shown to protect pancreatic β-cells against cytokine-induced dysfunction and destruction. The mechanisms through which GLP-1 exerts its effects are complex and still poorly understood. The aim of this study was to analyze the protein expression profiles of human islets of Langerhans treated with cytokines (IL-1β and IFN-γ) in the presence or absence of GLP-1 by 2D difference gel electrophoresis and subsequent protein interaction network analysis to understand the molecular pathways involved in GLP-1-mediated β-cell protection. Co-incubation of cytokine-treated human islets with GLP-1 resulted in a marked protection of β-cells against cytokine-induced apoptosis and significantly attenuated cytokine-mediated inhibition of glucose-stimulated insulin secretion. The cytoprotective effects of GLP-1 coincided with substantial alterations in the protein expression profile of cytokine-treated human islets, illustrating a counteracting effect on proteins from different functional classes such as actin cytoskeleton, chaperones, metabolic proteins, and islet regenerating proteins. In summary, GLP-1 alters in an integrated manner protein networks in cytokine-exposed human islets while protecting them against cytokine-mediated cell death and dysfunction. These data illustrate the beneficial effects of GLP-1 on human islets under immune attack, leading to a better understanding of the underlying mechanisms involved, a prerequisite for improving therapies for diabetic patients.status: publishe

Spironolactone inhibits production of proinflammatory cytokines, including tumour necrosis factor-α and interferon-γ, and has potential in the treatment of arthritis

Evidence suggests that spironolactone, an aldosterone antagonist, has effects on many cell types independent of its binding to cytosolic mineralocorticoid receptors. We tested the effects of spironolactone on ex vivo-activated human blood leucocytes using gene expression analyses (GeneChip®, 12 000 genes) and enzyme immunoassay for quantitating secreted pro- and anti-inflammatory cytokines. Furthermore, to evaluate the safety and efficacy of spironolactone as an anti-inflammatory drug 21 patients with rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA) or other arthritides were treated for up to 22 months with 1–3 mg/kg/day. Spironolactone, at in vivo attainable doses, markedly suppressed transcription of several proinflammatory cytokines and, accordingly, inhibited release of tumour necrosis factor, lymphotoxin, interferon-γ, granulocyte-macrophage colony-stimulating factor and interleukin 6 (70–90% inhibition). Release of these cytokines was also suppressed when testing whole blood from RA patients receiving 50 mg spironolactone twice daily, indicating that pharmaceutical use of the drug may suppress the release of inflammatory cytokines. Spironolactone therapy was generally well tolerated, although treatment had to be stopped in two adults on concomitant methotrexate therapy. Sixteen patients (76%) responded favourably. American College of Rheumatology criteria (ACR)20 or better was achieved in six of nine RA patients; four reached ACR70. Eight of nine JIA patients improved. In conclusion, spironolactone inhibits production of several proinflammatory cytokines considered to be of pathogenic importance in many immunoinflammatory diseases and shows positive effect in patients with chronic arthritis. Its effect as an anti-inflammatory drug should be explored, because prolonged spironolactone therapy is reasonably safe and economically attractive compared with many modern anti-inflammatory therapies