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Islet remodeling in female mice with spontaneous autoimmune and streptozotocin-induced diabetes.

Plesner A, Ten Holder JT, Verchere CB - PLoS ONE (2014)

Bottom Line: Islet alpha- and delta-cells are spared autoimmune destruction directed at beta-cells in type 1 diabetes resulting in an apparent increase of non-beta endocrine cells in the islet core.Serum levels of insulin, glucagon and GLP-1 were measured to compare hormone levels with respect to disease state.Alpha- or delta-cell mass in STZ-diabetic mice did not normalize by replacement of insulin via osmotic mini-pumps or islet transplantation.

View Article: PubMed Central - PubMed

Affiliation: Departments of Pathology and Laboratory Medicine, Child & Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.

ABSTRACT
Islet alpha- and delta-cells are spared autoimmune destruction directed at beta-cells in type 1 diabetes resulting in an apparent increase of non-beta endocrine cells in the islet core. We determined how islet remodeling in autoimmune diabetes compares to streptozotocin (STZ)-induced diabetes. Islet cell mass, proliferation, and immune cell infiltration in pancreas sections from diabetic NOD mice and mice with STZ-induced diabetes was assessed using quantitative image analysis. Serial sections were stained for various beta-cell markers and Ngn3, typically restricted to embryonic tissue, was only upregulated in diabetic NOD mouse islets. Serum levels of insulin, glucagon and GLP-1 were measured to compare hormone levels with respect to disease state. Total pancreatic alpha-cell mass did not change as autoimmune diabetes developed in NOD mice despite the proportion of islet area comprised of alpha- and delta-cells increased. By contrast, alpha- and delta-cell mass was increased in mice with STZ-induced diabetes. Serum levels of glucagon reflected these changes in alpha-cell mass: glucagon levels remained constant in NOD mice over time but increased significantly in STZ-induced diabetes. Increased serum GLP-1 levels were found in both models of diabetes, likely due to alpha-cell expression of prohormone convertase 1/3. Alpha- or delta-cell mass in STZ-diabetic mice did not normalize by replacement of insulin via osmotic mini-pumps or islet transplantation. Hence, the inflammatory milieu in NOD mouse islets may restrict alpha-cell expansion highlighting important differences between these two diabetes models and raising the possibility that increased alpha-cell mass might contribute to the hyperglycemia observed in the STZ model.

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Proliferation of endocrine cells and leukocytes in NOD and Balb/c mouse islets.Co-immunostaining for the nuclear proliferation marker BrdU (green) and islet hormones (red) in 4, 12 and 20 wk old female NOD (A) and age-matched Balb/c mice (B). Sections are counterstained with DAPI to visualize nuclei (and infiltrating immune cells). White arrows indicate double-positive cells, and white arrowheads indicate single BrdU-positive cells within the islet mantel. Scale bar = 10 µm.
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pone-0102843-g005: Proliferation of endocrine cells and leukocytes in NOD and Balb/c mouse islets.Co-immunostaining for the nuclear proliferation marker BrdU (green) and islet hormones (red) in 4, 12 and 20 wk old female NOD (A) and age-matched Balb/c mice (B). Sections are counterstained with DAPI to visualize nuclei (and infiltrating immune cells). White arrows indicate double-positive cells, and white arrowheads indicate single BrdU-positive cells within the islet mantel. Scale bar = 10 µm.

Mentions: To determine the degree of proliferating endocrine cells during ongoing beta-cell destruction in the NOD mouse, we quantified BrdU-labeled pancreas sections immunostained for glucagon, insulin or somatostatin (Fig. 5a and 6a). We observed sustained high levels of proliferating insulin-positive cells in all age groups (4 wk: 2.6±0.1%; 12 wk: 2.7±0.3%; 20 wk: 3.3±0.5%). By contrast, the high level of proliferating glucagon-positive cells found in young NOD mice (2.9±0.2%) decreased to 1.7±0.2% (p<0.01) in 12 wk old mice and further to 0.9±0.2% (p<0.001) in 20 wk old mice. Age-matched Balb/c mice demonstrated a similar significant decrease over time in the number of proliferating alpha, beta and delta-cells although the overall proliferative rate was ∼3-fold lower in this strain (Fig. 5b and 6b) compared to NOD mice. In the STZ model of diabetes, we found a significant increase in the number of proliferating alpha-cells compared to diabetic NOD mice (Fig. 6c) correlating with the significant increase in alpha-cell mass observed in this model (Fig. 4b). The degree of proliferation was confirmed by double immunostaining endocrine cells with Ki67 as an alternative marker (Figure S1). Both our pre-diabetic NOD mice and STZ-diabetic mice that received islet transplants to normalize fasting glycemia were found to have impaired glucose tolerance (data not shown). The higher post-prandial glucose excursions in these animals could contribute to islet cell proliferation despite the presence of normal fasting glycemia.


Islet remodeling in female mice with spontaneous autoimmune and streptozotocin-induced diabetes.

Plesner A, Ten Holder JT, Verchere CB - PLoS ONE (2014)

Proliferation of endocrine cells and leukocytes in NOD and Balb/c mouse islets.Co-immunostaining for the nuclear proliferation marker BrdU (green) and islet hormones (red) in 4, 12 and 20 wk old female NOD (A) and age-matched Balb/c mice (B). Sections are counterstained with DAPI to visualize nuclei (and infiltrating immune cells). White arrows indicate double-positive cells, and white arrowheads indicate single BrdU-positive cells within the islet mantel. Scale bar = 10 µm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4125302&req=5

pone-0102843-g005: Proliferation of endocrine cells and leukocytes in NOD and Balb/c mouse islets.Co-immunostaining for the nuclear proliferation marker BrdU (green) and islet hormones (red) in 4, 12 and 20 wk old female NOD (A) and age-matched Balb/c mice (B). Sections are counterstained with DAPI to visualize nuclei (and infiltrating immune cells). White arrows indicate double-positive cells, and white arrowheads indicate single BrdU-positive cells within the islet mantel. Scale bar = 10 µm.
Mentions: To determine the degree of proliferating endocrine cells during ongoing beta-cell destruction in the NOD mouse, we quantified BrdU-labeled pancreas sections immunostained for glucagon, insulin or somatostatin (Fig. 5a and 6a). We observed sustained high levels of proliferating insulin-positive cells in all age groups (4 wk: 2.6±0.1%; 12 wk: 2.7±0.3%; 20 wk: 3.3±0.5%). By contrast, the high level of proliferating glucagon-positive cells found in young NOD mice (2.9±0.2%) decreased to 1.7±0.2% (p<0.01) in 12 wk old mice and further to 0.9±0.2% (p<0.001) in 20 wk old mice. Age-matched Balb/c mice demonstrated a similar significant decrease over time in the number of proliferating alpha, beta and delta-cells although the overall proliferative rate was ∼3-fold lower in this strain (Fig. 5b and 6b) compared to NOD mice. In the STZ model of diabetes, we found a significant increase in the number of proliferating alpha-cells compared to diabetic NOD mice (Fig. 6c) correlating with the significant increase in alpha-cell mass observed in this model (Fig. 4b). The degree of proliferation was confirmed by double immunostaining endocrine cells with Ki67 as an alternative marker (Figure S1). Both our pre-diabetic NOD mice and STZ-diabetic mice that received islet transplants to normalize fasting glycemia were found to have impaired glucose tolerance (data not shown). The higher post-prandial glucose excursions in these animals could contribute to islet cell proliferation despite the presence of normal fasting glycemia.

Bottom Line: Islet alpha- and delta-cells are spared autoimmune destruction directed at beta-cells in type 1 diabetes resulting in an apparent increase of non-beta endocrine cells in the islet core.Serum levels of insulin, glucagon and GLP-1 were measured to compare hormone levels with respect to disease state.Alpha- or delta-cell mass in STZ-diabetic mice did not normalize by replacement of insulin via osmotic mini-pumps or islet transplantation.

View Article: PubMed Central - PubMed

Affiliation: Departments of Pathology and Laboratory Medicine, Child & Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.

ABSTRACT
Islet alpha- and delta-cells are spared autoimmune destruction directed at beta-cells in type 1 diabetes resulting in an apparent increase of non-beta endocrine cells in the islet core. We determined how islet remodeling in autoimmune diabetes compares to streptozotocin (STZ)-induced diabetes. Islet cell mass, proliferation, and immune cell infiltration in pancreas sections from diabetic NOD mice and mice with STZ-induced diabetes was assessed using quantitative image analysis. Serial sections were stained for various beta-cell markers and Ngn3, typically restricted to embryonic tissue, was only upregulated in diabetic NOD mouse islets. Serum levels of insulin, glucagon and GLP-1 were measured to compare hormone levels with respect to disease state. Total pancreatic alpha-cell mass did not change as autoimmune diabetes developed in NOD mice despite the proportion of islet area comprised of alpha- and delta-cells increased. By contrast, alpha- and delta-cell mass was increased in mice with STZ-induced diabetes. Serum levels of glucagon reflected these changes in alpha-cell mass: glucagon levels remained constant in NOD mice over time but increased significantly in STZ-induced diabetes. Increased serum GLP-1 levels were found in both models of diabetes, likely due to alpha-cell expression of prohormone convertase 1/3. Alpha- or delta-cell mass in STZ-diabetic mice did not normalize by replacement of insulin via osmotic mini-pumps or islet transplantation. Hence, the inflammatory milieu in NOD mouse islets may restrict alpha-cell expansion highlighting important differences between these two diabetes models and raising the possibility that increased alpha-cell mass might contribute to the hyperglycemia observed in the STZ model.

Show MeSH
Related in: MedlinePlus