ABSTRACT
BACKGROUND: Heat shock proteins (Hsp) act as intracellular chaperones and in addition are used as adjuvant in vaccines of peptides complexed with recombinant Hsp. By interacting with autologous peptides, Hsp may promote the induction of autoimmune reactivity. OBJECTIVE: Here, we analysed whether the effect of Hsp on macrophages is modulated by insulin peptides known to interact with Hsp. RESULTS: Combinations of the 70 kDa Hsp DnaK with peptide B11-23 from the core region of the proinsulin B-chain induced the release of the inflammatory mediators interleukin-6, tumor necrosis factor α, and interleukin-1ß from cells of human and murine macrophage lines. In parallel, there was high-affinity binding of B11-23 to DnaK. DnaK mixed with peptides from other regions of the insulin molecule did not stimulate cytokine secretion. DnaK alone induced little cytokine production, and peptides alone induced none. CONCLUSION: The macrophage-stimulating potential of Hsp70 family proteins when combined with the proinsulin B-chain peptide B11-23 may contribute to the immunodominance of this peptide in the development of beta cell-directed autoimmunity in type 1 diabetes.
Subject(s)
Autoantigens/metabolism , HSP70 Heat-Shock Proteins/metabolism , Macrophages/metabolism , Proinsulin/metabolism , Animals , Cell Line , Humans , Interleukin-1beta/metabolism , Interleukin-6/metabolism , Mice , Tumor Necrosis Factor-alpha/metabolismABSTRACT
OBJECTIVES: In this study, we analyzed the prognostic value of different MRI progression patterns for survival in patients with recurrent malignant glioma treated with the vascular endothelial growth factor antibody bevacizumab. PATIENTS AND METHODS: Twenty-six adult patients with recurrent malignant glioma treated with bevacizumab or bevacizumab/irinotecan were retrospectively analyzed for the development of contrast-enhanced (T1-weighted MRI) and T2/FLAIR lesions. According to the progression pattern, patients were divided into 3 subgroups: (1) patients with primarily progressive contrast-enhanced lesions in the first MRI after initiation of therapy ('primary PD group'); (2) patients with stable or regressive enhanced lesions but progressive FLAIR lesions ('FLAIR-only PD group'), and (3) patients with stable or regressive contrast-enhanced T1 and FLAIR lesions ('no PD group'). RESULTS: Overall survival (OS) in the 6 patients in the FLAIR-only PD group was not significantly different from the 11 patients in the no PD group (median 311 vs. 254 days, respectively). In contrast, survival in the FLAIR-only PD group was significantly better (p = 0.025) than in the primary PD group. CONCLUSION: FLAIR-only progression is not an independent prognostic factor negatively influencing OS in recurrent glioblastoma treated with bevacizumab and should not lead to discontinuation of bevacizumab therapy.
Subject(s)
Angiogenesis Inhibitors/therapeutic use , Antibodies, Monoclonal, Humanized/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Brain Neoplasms/drug therapy , Glioblastoma/drug therapy , Neoplasm Recurrence, Local/drug therapy , Neoplasm Recurrence, Local/pathology , Adult , Analysis of Variance , Bevacizumab , Brain Neoplasms/mortality , Brain Neoplasms/pathology , Camptothecin/administration & dosage , Camptothecin/analogs & derivatives , Disease Progression , Female , Germany/epidemiology , Glioblastoma/mortality , Glioblastoma/pathology , Humans , Irinotecan , Magnetic Resonance Imaging , Male , Middle Aged , Neoplasm Recurrence, Local/mortality , Prognosis , Retrospective Studies , Survival Analysis , Treatment OutcomeSubject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Melanoma/drug therapy , Melanoma/radiotherapy , Meningeal Neoplasms/drug therapy , Meningeal Neoplasms/radiotherapy , Combined Modality Therapy , Cytarabine/administration & dosage , Dacarbazine/administration & dosage , Dacarbazine/analogs & derivatives , Humans , Injections, Spinal , Liposomes/administration & dosage , Male , Middle Aged , TemozolomideABSTRACT
BACKGROUND: Chaperones facilitate proper folding of peptides and bind to misfolded proteins as occurring during periods of cell stress. Complexes of peptides with chaperones induce peptide-directed immunity. Here we analyzed the interaction of (pre)proinsulin with the best characterized chaperone of the hsp70 family, bacterial DnaK. RESULTS: Of a set of overlapping 13-mer peptides of human preproinsulin high affinity binding to DnaK was found for the signal peptide and one further region in each proinsulin domain (A- and B-chain, C-peptide). Among the latter, peptides covering most of the B-chain region B11-23 exhibited strongest binding, which was in the range of known high-affinity DnaK ligands, dissociation equilibrium constant (K'd) of 2.2 ± 0.4 µM. The B-chain region B11-23 is located at the interface between two insulin molecules and not accessible in insulin oligomers. Indeed, native insulin oligomers showed very low DnaK affinity (K'd 67.8 ± 20.8 µM) whereas a proinsulin molecule modified to prevent oligomerization showed good binding affinity (K'd 11.3 ± 7.8 µM). CONCLUSIONS: Intact insulin only weakly interacts with the hsp70 chaperone DnaK whereas monomeric proinsulin and peptides from 3 distinct proinsulin regions show substantial chaperone binding. Strongest binding was seen for the B-chain peptide B 11-23. Interestingly, peptide B11-23 represents a dominant autoantigen in type 1 diabetes.
