phenanthrenes and Diabetes-Mellitus--Type-1

Triptolide (TPL) possesses profound immunosuppressive effects and has potential in allograft transplantation. We investigated whether TPL treatment prevents autoimmune diabetes in nonobese diabetic (NOD) mice and prolongs the survival of islet grafts against autoimmune attack or allograft rejection.. Diabetic incidence was monitored in TPL-treated NOD mice. Nonobese diabetic or BALB/c islets were transplanted into diabetic recipients treated with TPL. Different T-cell subsets in grafts or spleen were analyzed. The proliferation, apoptosis, cytokines, and activities of AKT, NFκB, and caspases 3, 8, and 9 of T cells were determined.. Diabetic incidence was reduced and inflammatory cytokines were decreased in islets and spleen under TPL treatment. T-cell proliferation was reduced and the survival of syngeneic or allogeneic grafts was significantly increased in TPL-treated mice. The populations of CD4, CD8, CD4CD69, CD8CD69, and interferon-γ-producing T cells in islet grafts and spleen were reduced. Triptolide treatment increased the apoptosis of T cells in the spleen of recipients. Levels of phosphorylated protein kinase B and phosphorylated inhibitor of kappa B in splenocytes were reduced and caspases 3, 8, and 9 were increased in TPL-treated mice.. Triptolide treatment not only reduced the diabetic incidence in NOD mice but also prolonged the survival of syngeneic or allogeneic grafts.

Topics: Animals; Apoptosis; Blotting, Western; Caspases; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cell Proliferation; Cytokines; Diabetes Mellitus, Type 1; Diterpenes; Epoxy Compounds; Female; Flow Cytometry; Graft Survival; Immunosuppressive Agents; Interferon-gamma; Islets of Langerhans; Islets of Langerhans Transplantation; Mice; Mice, Inbred BALB C; Mice, Inbred NOD; Mice, SCID; NF-kappa B; Phenanthrenes; Proto-Oncogene Proteins c-akt; Spleen

Our goal was to identify the role of poly(ADP-ribose) polymerase (PARP) in cerebrovascular dysfunction in Type 1 diabetes mellitus (T1D). In a first series of studies, rats were assigned to nondiabetic and diabetic (streptozotocin; 50 mg/kg IP) groups. Two to three months after injection of streptozotocin, we examine in vivo responses of pial arterioles to nitric oxide synthase (NOS)-dependent (adenosine diphosphate (ADP), acetylcholine and histamine) and -independent (nitroglycerin) agonists. After the initial examination of reactivity to the agonists, we treated pial arterioles acutely with an inhibitor of PARP (PJ-34; 1 microM), and then we again examined responses to the agonists. In a second series of studies, we examine superoxide production (lucigenin chemiluminescence) by parietal cortex tissue in nondiabetic and diabetic rats. We found that dilation of pial arterioles in response to ADP, acetylcholine and histamine, but not to nitroglycerin, was impaired in diabetic compared to nondiabetic rats. In addition, although PJ-34 did not alter responses in nondiabetic rats, PJ-34 alleviated T1D-induced impairment of NOS-dependent vasodilation. We also found that basal production of superoxide was increased in diabetic compared to nondiabetic rats and that PJ-34 decreased this basal production of superoxide. Our findings suggest that T1D impairs NOS-dependent reactivity of cerebral arterioles by a mechanism that appears to be related to the formation of superoxide via activation of PARP.

Topics: Acetylcholine; Adenosine Diphosphate; Animals; Arterioles; Blood Glucose; Blood Pressure; Body Weight; Cerebrovascular Circulation; Cerebrovascular Disorders; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Enzyme Inhibitors; Histamine; Male; Models, Biological; Nitroglycerin; Parietal Lobe; Phenanthrenes; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Rats; Rats, Sprague-Dawley; Superoxides; Vasodilation

Poly (ADP-ribose) polymerase (PARP) is a nuclear enzyme that consumes NAD in response to DNA strand breaks. The PARP inhibitor nicotinamide prevents NAD consumption and protects islet beta-cells from chemically induced necrosis but not cytokine-induced apoptosis. Therefore, it is unclear how nicotinamide protects NOD mice from autoimmune diabetes in which apoptosis is the mode of beta-cell death. To investigate the mechanism of diabetes prevention by PARP inhibition, we studied the effects of a novel, potent PARP inhibitor, PJ34, a phenanthridinone derivative, on diabetes development in NOD mice and on diabetes recurrence in diabetic NOD mice transplanted with syngeneic islets. PJ34 administration from age 5 or 15 weeks significantly decreased insulitis, beta-cell destruction and diabetes incidence, and protection from diabetes continued for 12 weeks after PJ34 therapy was stopped. Similarly, syngeneic islet graft survival was prolonged and outlasted therapy in PJ34-treated mice. Immunohistochemical studies revealed significantly fewer leukocytes in islet grafts of PJ34-treated mice, together with increased apoptosis of these cells and decreased expression of the T helper 1-type cytokine interferon (IFN)-gamma. These results suggest that PARP inhibition protects against autoimmune beta-cell destruction in NOD mice by inducing apoptosis of islet-infiltrating leukocytes and decreasing IFN-gamma expression in the islets.

Topics: Aging; Animals; Apoptosis; Diabetes Mellitus, Type 1; Enzyme Inhibitors; Interferon-gamma; Interleukins; Islets of Langerhans; Islets of Langerhans Transplantation; Leukocytes; Mice; Mice, Inbred NOD; Niacinamide; Phenanthrenes; Poly(ADP-ribose) Polymerase Inhibitors; Recurrence; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors; Transplantation, Isogeneic