beta cell protecting and immunomodulatory activities of Paecilomyces Hepiali Chen mycelium in STZ induced T1DM mice.

The anti-hyperglycemic and immunomodulatory activities of the ethanol extract from Paecilomyces Hepiali Chen (PHC), a Chinese medicine, were investigated in streptozotocin-induced type 1 diabetic (T1DM) mice. Male Balb/c mice, which were i.p. injected with streptozotocin (STZ, 50 mg/kg, for 5 consecutive days) on Day 7, were orally administered saline (the normal control and diabetic control group), Metformin (60 mg/kg, b.w., positive group), or the extract (100 mg/kg, b.w., PHC prevention group) from Day 1 to Day 28, Mice i.p. injected with streptozotocin (STZ, 50 mg/kg, b.w.) for 5 consecutive days prior to PHC treatment (100 mg/kg, b.w.) were used as the PHC treatment group. The effects of PHC on postprandial blood glucose concentrations, plasmatic insulin levels, morphology of pancreatic beta cells and CD4(+) T cells proliferation after 28-day treatment were monitored. Results showed that PHC administered 6 days before STZ induction of diabetes in mice significantly decreased blood glucose level (p < 0.01). An increase of insulin level was also observed as compared to those in the diabetic control group (p < 0.01). In addition, fewer inflammatory cells infiltrated the pancreatic islet and fewer beta cells death by apoptosis within the inflamed islets were observed. More importantly, the CD4(+) T cell proliferation was remarkably attenuated ex vivo in mice preventively treated with PHC (p < 0.01). In comparison to the PHC prevention group, no significant hypoglycemia, changes of insulin level and beta cell protection were observed in mice treated with PHC after STZ administration. Our findings demonstrated that preventive administration of PHC protected beta cells from apoptosis in type 1 diabetes induced by STZ, and the underlying mechanism may be involved in suppressing CD4(+) T cells reaction, reducing inflammatory cells infiltration and protecting beta cell apoptosis in pancreatic islet.

Diabetogenic T cells induce autoimmune diabetes in BALB/c mice.

OBJECTIVE: To investigate the role of T cell and its subsets in the induction of insulitis and type 1 diabetes mellitus (T1DM) in BALB/c mice. METHODS: Autoimmune diabetes mellitus was developed by intraperitoneal injection of 40 mg/kg streptozotocin (STZ) daily for 5 consecutive days in BALB/c mice as sources of donor cells. Spleen cells from diabetic mice were then cultured for 7 days in the stimulation of interleukin-2 (IL-2) to harvest diabetogenic T cells, which were subsequently transferred into normal BALB/c mice recipients. MTT, ELISA, and HE staining were used to analyze the lymphocyte proliferation, cytokine (IL-2, interferon-gamma, IL-4, and IL-10) levels, and pathological changes in pancreatic islets. RESULTS: As few as 3 x 10(6) diabetogenic T cells successfully induced diabetes mellitus in recipients pretreated with STZ twice, whereas transfer of equal amount of normal splenocytes, T cell-depleted diabetogenic splenocytes, or diabetogenic CD4+ T cells alone in recipients receiving STZ twice pretreatment was proved not to induce diabetes mellitus either. A markedly increased lymphocyte proliferation, high levels of interferon-gamma and IL-2 in the supernatants of diabetogenic T cells were observed. In addition, a markedly enhanced lymphocyte proliferation, a high level of interferon-gamma secretion in serum, and numerous lymphocytes infiltration in pancreatic islets were detected in the diabetic mice induced by diabetogenic T cells transfer. CONCLUSIONS: A novel T1DM murine model is established in STZ-pretreated BALB/c mice by adoptive transfer of diabetogenic T cells. CD4+ T cells with interferon-gamma may promote the onset of diabetes mellitus.

Immune tolerance induced by adoptive transfer of dendritic cells in an insulin-dependent diabetes mellitus murine model.

AIM: To investigate the effect and underlying mechanisms of immune-tolerance induced by the adoptive transfer of bone marrow (BM)-derived dendritic cells (DC) in insulin-dependent diabetes mellitus (IDDM) mice. METHODS: The IDDM model was established by a low dose of streptozotocin (STZ) in Balb/c mice. Two DC subpopulations were generated from the BM cells with granulocyte-macrophage colony-stimulating factor with or without interleukin-4. The purity and the T cell stimulatory capability of DC were identified. These cells were used to modulate autoimmune response in pre-diabetic mice. Blood glucose was examined weekly; pancreas tissues were taken for histopathological analysis, and CD4(+) T cells were isolated to detect lymphocyte proliferation by MTT assay and the ratio of CD4(+)CD25(+) T cells by fluorescence-activated cell sorting (FACS). The cytokine secretion was determined by ELISA analysis. RESULTS: Two DC subsets were generated from BM, which have phenotypes of mature DC (mDC) and immature DC (iDC), respectively. The level of blood glucose decreased significantly by transferring iDC (P< 0.01) rather than mDC. Less lymphocyte infiltration was observed in the islets, and pancreatic structure was intact. In vitro, proliferation of lymphocytes decreased and the proportion of CD4(+)CD25(+) T cells increased remarkably, compared with the mDC-treated groups (P< 0.05), which were associated with increased level of the Th2 cytokine and reduced level of the Th1 cytokine after iDC transfer. CONCLUSION: Our data showed that iDC transfer was able to confer protection to mice from STZ-induced IDDM. The immune-tolerance to IDDM may be associated with promoting the production of CD4(+)CD25(+) T cells and inducing regulatory Th2 responses in vivo.