Heat shock protein (HSP) 60 nonspecifically activates cells of the innate immune system. In the present study, we characterized the effects of human HSP60 maturation, cytokine release, and T cell-activating capacity of bone marrow-derived dendritic cells (DC). Furthermore, we analyzed HSP60-induced signal transduction in DC. HSP60 strongly stimulated DC for maturation and release of TNF-α, IL-12, and IL-1β. However, HSP60 elicited only a weak IL-10 response in DC suggesting a Th1 bias. HSP60-treated DC induced proliferation of allogeneic T cells. Again, a Th1 bias was noted in that cocultures of allogeneic T cells and HSP60-treated DC released IFN-γ but only small amounts of IL-10 and no detectable IL-4. Signaling via Toll-like receptor 4 was involved in HSP60-induced cytokine release and maturation because DC of C3H/HeJ mice with a mutant Toll-like receptor 4 showed deficient response to HSP60. HSP60 was found to rapidly activate the mitogen-activated protein kinases p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinase as well as IκB in DC. Phosphorylation of these signaling molecules was also mediated by LPS, but with much slower kinetics. Thus, HSP60 stimulates DC more rapidly than LPS and elicits a Th1-promoting phenotype. These results suggest that DC play a pivotal role in priming for destructive Th1-type responses at sites of local HSP60 release.

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Administration of DiaPep277 seems safe and may have beneficial effects on C-peptide levels over time in some patients with T1D, but this finding was not accompanied by reduced HbA1c or insulin requirement. Studies with more patients and longer follow-up are needed to further study the effect of DiaPep277.

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Diabetes mellitus type 1 is a chronic disease in which the insulin-secreting ss-cells are selectively destroyed by an immune-mediated process. Autoantibodies directed against several islet antigens are useful parameters to estimate the risk to develop diabetes, but cell-mediated immunity involving T lymphocytes plays a major part in causing the specific destruction of ss-cells. T cells are characterized by their antigen-specificity, phenotype and cytokine-secreting profile. T cells that secrete cytokines of the T helper 1 (Th1) type have been shown to transfer diabetes in animal studies, in contrast to T helper 2 (Th2) cytokine-secreting T cells that are thought to be rather nondestructive. In the absence of phenotypic markers for Th1 and Th2 cells, several different approaches have been taken to examine T cell responses in detail. Methods involve T-cell proliferation assays, Enzyme-Linked-Immuno-Sorbent-Assay (ELISA) analysis of secreted cytokines and phenotype analysis applying flow cytometry. A more recent development is ELISPOT analysis, which enables the investigator to determine the qualitative and quantitative antigen-specific immune response on a single-cell level with regard to cytokine secretion. This article aims to give an introduction to the advantages and limitations inherent in the different techniques and their potential relevance for immunological studies in diabetes mellitus type 1.

SummaryOral administration of proteases such as bromelain and papain is commonly used in patients with a wide range of inflammatory conditions, but their molecular and cellular mechanisms of action are still poorly understood. The aim of our study was to investigate the impact of these proteases on the release of interleukin-6 (IL-6) and other cytokines in the recently described modified mixed lymphocyte culture (MMLC) test system which is based on the mutual interaction of cells of the innate and adaptive immunity. Bromelain and papain enhanced IL-6 production dose-dependently up to 400-fold in MMLC before and up to 30-fold after neutralization of LPS content of proteases using polymyxin B, indicating that IL-6 induction by protease treatment was attributable to both protease action and LPS content of enzyme preparations. The production of IFNγ γ γ γ and IL-10 was not altered by bromelain or papain, indicating a selective and differential immune activation. Both proteases impaired cytokine stability, cell proliferation and expression of cell surface molecules like CD14 only marginally, suggesting no impact of these mechanisms on protease-mediated cytokine release. These findings might provide the mechanistic rationale for the current use of proteases in wound healing and tissue regeneration since these processes depend on IL-6 induction.