[Show abstract][Hide abstract] ABSTRACT: Proteases are used in therapy for autoimmune diseases yet the mechanism of their action remains to be determined. We studied the immunological basis of protease therapy in the context of Type I (insulin-dependent) diabetes mellitus.
We studied the effects of proteases (trypsin, papain, chymotrypsin, bromelain) on immune reactivity of a series of autoreactive T-cell clones from prediabetic subjects and patients with a recent onset of Type I diabetes and specific to the autoantigens GAD65, IA-2 and insulin-secretory granule protein.
Cell surface expression of adhesion, co-stimulatory and homing molecules on both antigen-presenting cells and T cells was changed after protease treatment. Cytokine analyses showed a selective inhibition of proinflammatory (Th-1) but not Th-2 cytokine production. Autoreactive T-cell proliferation was inhibited at pharmacological serum concentrations, whereas non-specific proliferation to phytohaemagglutinin was not affected at these concentrations. Preincubation experiments on T cells and antigen-presenting cells separately showed that this effect was mediated by APCs, but not T-cells.
Proteases have pleiotropic immunological effects supporting an immunomodulatory potential for the intervention of chronic inflammatory diseases and Th-1 mediated oedema formation.
[Show abstract][Hide abstract] ABSTRACT: Adhesion molecules are important for leukocyte extravasation and for the delivery of costimulatory signals in T cell activation. We therefore interfered in the immune process leading to islet inflammation in diabetes prone NOD mice by oral vaccination with plasmid DNA encoding soluble ICAM-1. Female NOD mice were treated orally with ICAM-1, TGF-beta, or control plasmid DNA and received a single injection of cyclophosphamide for synchronization and acceleration of the disease process in the pancreas. Quantitative RT-PCR analysis of pancreatic mRNA showed that cyclophosphamide induced the expression of Th1 cytokines (IFN-gamma and IL-12p40) in vehicle- or control plasmid-treated mice. Treatment with ICAM-1 and TGF-beta DNA resulted in increased levels of IL-10 mRNA in the pancreas, indicating an anti-inflammatory regulatory immune response. Histological analysis of pancreatic islets showed that the DNA treatment did not alter islet infiltration in response to cyclophosphamide. Hence vaccination with the ICAM-1 plasmid had not suppressed leukocyte migration but rather modulated lymphocyte activity, similarly as seen for the TGF-beta-encoding plasmid. Neither of the three plasmids caused recognizable changes in cytokine expression in the small intestine, Peyer's patches, or mesenteric lymph nodes. We conclude that oral vaccination with DNA encoding immunoregulatory molecules such as ICAM-1 and TGF-beta represents an approach for modulating the ongoing inflammatory process in the pancreas of diabetes prone NOD mice.
Journal of Molecular Medicine 06/2002; 80(5):301-8. DOI:10.1007/s00109-002-0324-8 · 5.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Intercellular adhesion molecule (ICAM)-1 is involved in forming the immunological synapse. The contribution of ICAM-1 to immune responses is not critical because mice with a disrupted ICAM-1 gene do not have grossly abnormal immune reactivity. Here we report on the surprising finding that diabetes-prone NOD mice with a disrupted ICAM-1 gene (ICAM-1(-/-)) are completely protected from disease development. While 64% of ICAM-1(+/+) and 44% of ICAM-1(+/-) female NOD mice developed overt diabetes until 310 days old, no ICAM-1(-/-) NOD mice became hyperglycaemic. Histological examinations revealed minor infiltration around pancreatic islets of ICAM1(-/-) NOD mice. Administration of cyclophosphamide caused a progression to severe islet destruction in ICAM-1(+/+) NOD mice within 10 days. In contrast, ICAM-1(-/-) mice showed only mild insulitis. Furthermore, ICAM-1(+/+) NOD mice showed an increase of IFN-gamma, interleukin (IL)-12p40 and IL-12p35 pancreatic mRNA levels, leading to an increased ratio of IFN-gamma: IL-4 and IL-12p40: IL-12p35 expression. In contrast, ICAM-1(-/-) NOD mice did not upregulate IFN-gamma or IL-12p40 gene expression but maintained IL-4 and increased IL-12p35 gene expression. These results identify a dominant and non-redundant role of ICAM-1 in the development of autoimmune diabetes.
Journal of Autoimmunity 10/2001; 17(2):109-17. DOI:10.1006/jaut.2001.0526 · 8.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mice deficient in intercellular adhesion molecule-1 (ICAM-1), lacking membranous ICAM-1, show a normal development but abnormalities of inflammatory and immune functions. Although the membrane-bound form of ICAM-1 is not detectable in the mutant strain, circulating ICAM-1 (cICAM) is present in serum from ICAM-1-deficient mice in similar amounts as in serum from wild-type mice. These findings were confirmed in vitro by flow cytometric analysis of lipopolysaccharide-stimulated spleen cells, and cICAM-enzyme-linked immunosorbent assay analysis of supernatants of cultured spleen cells. To analyze for the source of cICAM-1, spleen cell RNA was isolated and ICAM-1 RNA was amplified by reverse transcriptase-polymerase chain reaction using primers binding in the 5' and 3' untranslated regions. Different fragments were cloned and sequenced. In wild-type RNA the common 5 domain form of ICAM-1 was identified. In RNA from ICAM-1 mutant mice only 3 smaller fragments were found. Sequencing these fragments identified 3 alternatively spliced isoforms of ICAM-1, lacking 2 or 3 extracellular domains. However, in all spliced fragments the transmembrane domain was included. Therefore, we postulate that circulating forms of ICAM-1 are generated by proteolytic cleavage of membranous ICAM-1. The data indicate that the expression of membranous ICAM-1 and the appearance of circulating forms in serum are independently regulated mechanisms. (Blood. 2000;95:1350-1355)
[Show abstract][Hide abstract] ABSTRACT: Multiple injections of low-dose streptozotocin (LDSZ) induce immune-mediated insulitis and diabetes in C57BL/6 (H-2b) mice. To evaluate the role of the intercellular adhesion molecule-1 (ICAM-1) for LDSZ induced immune-mediated diabetes, we have investigated mice genetically deficient in the ICAM-1 gene (ICAM-1-/-) in comparison to wild-type (ICAM-1+/+) mice. ICAM-1-/- mice, which had a mixed genetic background of C57BL/6 and DBA/2 mice, were backcrossed to C57BL/6 mice and screened for H2b homogenicity. Mice received five daily injections of 40 mg/kg streptozotocin. On day 21 after the first LDSZ injection 55% of the ICAM-1+/+ (female 33%, male 80%) and 50% of the ICAM-1-/- (female 20%, male 100%), mice had blood glucose levels over 200 mg/dl. Mean blood glucose levels increased in response to LDSZ treatment, however, no differences between ICAM-1+/+ and ICAM-1-/- mice were noted. Histological examinations of pancreatic islets revealed mononuclear infiltration of pancreatic islets without significant differences between both groups of mice. In summary, LDSZ-induced immune-mediated insulitis and diabetes development occurs in ICAM-1-/- mice similarly than in ICAM-1+/+ mice. These results do not support the hypothesis that ICAM-1 plays a key role during immune-mediated infiltration and destruction of pancreatic islets in LDSZ induced diabetes.
Hormone and Metabolic Research 01/2000; 31(12):636-40. DOI:10.1055/s-2007-978812 · 2.12 Impact Factor