Limits...
The involvement of interleukin-22 in the expression of pancreatic beta cell regenerative Reg genes.

Hill T, Krougly O, Nikoopour E, Bellemore S, Lee-Chan E, Fouser LA, Hill DJ, Singh B - Cell Regen (Lond) (2013)

Bottom Line: This was associated with increased islet Regenerating (Reg) genes expression, and elevated IL-22-producing Th17 T-cells in the pancreas.Our results showed: 1) Reg1 and Reg2 mRNA abundance to be significantly increased in IL-22-treated islets in vitro; 2) IL-22 mRNA expression in the pre-diabetic mouse pancreas increased with time following CFA treatment; 3) a reduced expression of IL-22Rα following CFA treatment; 4) a down-regulation in Reg1 and Reg2 mRNA expression in the pancreas of pre-diabetic mice injected with an IL-22 neutralizing antibody; and 5) an increased islet β-cell DNA synthesis in vitro in the presence of IL-22.We conclude that IL-22 may contribute to the regeneration of β-cells by up-regulating Regenerating Reg1 and Reg2 genes in the islets.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, University of Western Ontario, London, ON Canada.

ABSTRACT

Background: In Type 1 diabetes, the insulin-producing β-cells within the pancreatic islets of Langerhans are destroyed. We showed previously that immunotherapy with Bacillus Calmette-Guerin (BCG) or complete Freund's adjuvant (CFA) of non-obese diabetic (NOD) mice can prevent disease process and pancreatic β-cell loss. This was associated with increased islet Regenerating (Reg) genes expression, and elevated IL-22-producing Th17 T-cells in the pancreas.

Results: We hypothesized that IL-22 was responsible for the increased Reg gene expression in the pancreas. We therefore quantified the Reg1, Reg2, and Reg3δ (INGAP) mRNA expression in isolated pre-diabetic NOD islets treated with IL-22. We measured IL-22, and IL-22 receptor(R)-α mRNA expression in the pancreas and spleen of pre-diabetic and diabetic NOD mice. Our results showed: 1) Reg1 and Reg2 mRNA abundance to be significantly increased in IL-22-treated islets in vitro; 2) IL-22 mRNA expression in the pre-diabetic mouse pancreas increased with time following CFA treatment; 3) a reduced expression of IL-22Rα following CFA treatment; 4) a down-regulation in Reg1 and Reg2 mRNA expression in the pancreas of pre-diabetic mice injected with an IL-22 neutralizing antibody; and 5) an increased islet β-cell DNA synthesis in vitro in the presence of IL-22.

Conclusions: We conclude that IL-22 may contribute to the regeneration of β-cells by up-regulating Regenerating Reg1 and Reg2 genes in the islets.

No MeSH data available.


Related in: MedlinePlus

A model for cytokine-mediated up-regulation of theβ-cellReggenes leading toβ-cell regeneration. Interleukin-22 (red) binds to its receptor complex, IL-22Rα/IL-10Rβ, which activates the Stat3 transcription factor protein (1), STAT3 then migrates into the nucleus of the β-cell and stimulates Reg gene transcription and translation (green). Secreted Reg proteins are then thought to activate Cyclin D1. This allows the β-cell to enter the G1/S transition of the cell cycle leading to regeneration. IL-22 can also activate the MAP3 kinases leading to Cyclin D1 (2), which in turn inactivates the Retinoblastoma (Rb). Platelet-derived growth factor (PDGF) (blue) similarly leads the activation of Cyclin D1, which in turn inactivates Rb allowing the release of sequestered transcription factors (TF) essential for the G1–S progression of the cell cycle. Reg2 gene expression by activating Stat3, believed to be caused by receptor-induced Src kinase activity. The known signaling pathways (black and blue) and the proposed signaling pathways (green) are identified.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4230743&req=5

Fig6: A model for cytokine-mediated up-regulation of theβ-cellReggenes leading toβ-cell regeneration. Interleukin-22 (red) binds to its receptor complex, IL-22Rα/IL-10Rβ, which activates the Stat3 transcription factor protein (1), STAT3 then migrates into the nucleus of the β-cell and stimulates Reg gene transcription and translation (green). Secreted Reg proteins are then thought to activate Cyclin D1. This allows the β-cell to enter the G1/S transition of the cell cycle leading to regeneration. IL-22 can also activate the MAP3 kinases leading to Cyclin D1 (2), which in turn inactivates the Retinoblastoma (Rb). Platelet-derived growth factor (PDGF) (blue) similarly leads the activation of Cyclin D1, which in turn inactivates Rb allowing the release of sequestered transcription factors (TF) essential for the G1–S progression of the cell cycle. Reg2 gene expression by activating Stat3, believed to be caused by receptor-induced Src kinase activity. The known signaling pathways (black and blue) and the proposed signaling pathways (green) are identified.

Mentions: The exact mechanism underlying CFA-induced Reg gene upregulation has not been clearly defined. Experiments in the past have shown IL-6 to be an intermediate for Reg2 and Reg1 gene induction in the pancreas, since the IL-6 upstream response element is conserved among these Reg genes [5, 22]. Since IL-6 signaling leads to the activation of Stat3 transcription factors inside target cells [23], it was believed that Reg2 gene induction was also Stat-3 mediated [7]. Our results confirm and extend the role of the cytokine, IL-22, in up-regulating the Reg2 gene as well as Reg1, thus supporting our original hypothesis. We confirmed a 3-fold and 4.2-fold increase in Reg2 and Reg1 gene expression respectively when pre-diabetic (6-week-old) pancreatic islets were incubated with 10 ng/mL of recombinant IL-22 in vitro for 48 hrs. We have previously shown that the PCR results for the expression of Reg genes in the pancreatic islets in our studies correlate with the expression of Reg proteins by using Western blot assay [5]. This suggests that Reg2 gene expression, like Reg1, can be induced via Stat3 signaling and that IL-22 may be an immune response-mediated agent for the induction of these Reg genes within the pancreatic islets during insulitis [7, 16] (Figure 6). This finding is supported by a previous study by Aggarwal et al.[16], who had shown that the in vivo injection of IL-22 resulted in a rapid induction of Reg2 expression in the pancreas of C57/BL6 mice. Interestingly, in our in vitro study recombinant IL-22 resulted in a noticeable down-regulation of Reg2 and Reg1 expression in the islets from 6-week-old NOD mice when incubated with high concentrations (50 ng/mL) of IL-22. This may suggest that pancreatic β-cells exhibit a dose-dependent response to IL-22, and that an excess of the cytokine may be inhibitory to islet Reg gene expression. In contrast to the other Reg genes, the expression of Reg3δ was not affected by IL-22 treatment in the pancreatic islets and thus confirms past studies showing Reg3δ expression to be absent in the α- and β-cells. We also found Reg2 and Reg1 expression to be drastically reduced in the pancreas of pre-diabetic mice injected with a neutralizing IL-22 antibody, confirming that IL-22 is an upstream activator for these Reg genes. These findings support the study by Zhang et al.[24] who found the Reg1 and Reg2 genes to be induced by IL-22 in the colonic epithelial cells of Citrobacter rodentium-infected WT mice, but for expression to be completely abolished in IL-22 knock-out infected mice. As shown by our studies with Th17 supernatant, cytokines other than IL-22 may contribute to the upregulation of Reg genes. We are currently exploring this possibility in our laboratory.Figure 6


The involvement of interleukin-22 in the expression of pancreatic beta cell regenerative Reg genes.

Hill T, Krougly O, Nikoopour E, Bellemore S, Lee-Chan E, Fouser LA, Hill DJ, Singh B - Cell Regen (Lond) (2013)

A model for cytokine-mediated up-regulation of theβ-cellReggenes leading toβ-cell regeneration. Interleukin-22 (red) binds to its receptor complex, IL-22Rα/IL-10Rβ, which activates the Stat3 transcription factor protein (1), STAT3 then migrates into the nucleus of the β-cell and stimulates Reg gene transcription and translation (green). Secreted Reg proteins are then thought to activate Cyclin D1. This allows the β-cell to enter the G1/S transition of the cell cycle leading to regeneration. IL-22 can also activate the MAP3 kinases leading to Cyclin D1 (2), which in turn inactivates the Retinoblastoma (Rb). Platelet-derived growth factor (PDGF) (blue) similarly leads the activation of Cyclin D1, which in turn inactivates Rb allowing the release of sequestered transcription factors (TF) essential for the G1–S progression of the cell cycle. Reg2 gene expression by activating Stat3, believed to be caused by receptor-induced Src kinase activity. The known signaling pathways (black and blue) and the proposed signaling pathways (green) are identified.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230743&req=5

Fig6: A model for cytokine-mediated up-regulation of theβ-cellReggenes leading toβ-cell regeneration. Interleukin-22 (red) binds to its receptor complex, IL-22Rα/IL-10Rβ, which activates the Stat3 transcription factor protein (1), STAT3 then migrates into the nucleus of the β-cell and stimulates Reg gene transcription and translation (green). Secreted Reg proteins are then thought to activate Cyclin D1. This allows the β-cell to enter the G1/S transition of the cell cycle leading to regeneration. IL-22 can also activate the MAP3 kinases leading to Cyclin D1 (2), which in turn inactivates the Retinoblastoma (Rb). Platelet-derived growth factor (PDGF) (blue) similarly leads the activation of Cyclin D1, which in turn inactivates Rb allowing the release of sequestered transcription factors (TF) essential for the G1–S progression of the cell cycle. Reg2 gene expression by activating Stat3, believed to be caused by receptor-induced Src kinase activity. The known signaling pathways (black and blue) and the proposed signaling pathways (green) are identified.
Mentions: The exact mechanism underlying CFA-induced Reg gene upregulation has not been clearly defined. Experiments in the past have shown IL-6 to be an intermediate for Reg2 and Reg1 gene induction in the pancreas, since the IL-6 upstream response element is conserved among these Reg genes [5, 22]. Since IL-6 signaling leads to the activation of Stat3 transcription factors inside target cells [23], it was believed that Reg2 gene induction was also Stat-3 mediated [7]. Our results confirm and extend the role of the cytokine, IL-22, in up-regulating the Reg2 gene as well as Reg1, thus supporting our original hypothesis. We confirmed a 3-fold and 4.2-fold increase in Reg2 and Reg1 gene expression respectively when pre-diabetic (6-week-old) pancreatic islets were incubated with 10 ng/mL of recombinant IL-22 in vitro for 48 hrs. We have previously shown that the PCR results for the expression of Reg genes in the pancreatic islets in our studies correlate with the expression of Reg proteins by using Western blot assay [5]. This suggests that Reg2 gene expression, like Reg1, can be induced via Stat3 signaling and that IL-22 may be an immune response-mediated agent for the induction of these Reg genes within the pancreatic islets during insulitis [7, 16] (Figure 6). This finding is supported by a previous study by Aggarwal et al.[16], who had shown that the in vivo injection of IL-22 resulted in a rapid induction of Reg2 expression in the pancreas of C57/BL6 mice. Interestingly, in our in vitro study recombinant IL-22 resulted in a noticeable down-regulation of Reg2 and Reg1 expression in the islets from 6-week-old NOD mice when incubated with high concentrations (50 ng/mL) of IL-22. This may suggest that pancreatic β-cells exhibit a dose-dependent response to IL-22, and that an excess of the cytokine may be inhibitory to islet Reg gene expression. In contrast to the other Reg genes, the expression of Reg3δ was not affected by IL-22 treatment in the pancreatic islets and thus confirms past studies showing Reg3δ expression to be absent in the α- and β-cells. We also found Reg2 and Reg1 expression to be drastically reduced in the pancreas of pre-diabetic mice injected with a neutralizing IL-22 antibody, confirming that IL-22 is an upstream activator for these Reg genes. These findings support the study by Zhang et al.[24] who found the Reg1 and Reg2 genes to be induced by IL-22 in the colonic epithelial cells of Citrobacter rodentium-infected WT mice, but for expression to be completely abolished in IL-22 knock-out infected mice. As shown by our studies with Th17 supernatant, cytokines other than IL-22 may contribute to the upregulation of Reg genes. We are currently exploring this possibility in our laboratory.Figure 6

Bottom Line: This was associated with increased islet Regenerating (Reg) genes expression, and elevated IL-22-producing Th17 T-cells in the pancreas.Our results showed: 1) Reg1 and Reg2 mRNA abundance to be significantly increased in IL-22-treated islets in vitro; 2) IL-22 mRNA expression in the pre-diabetic mouse pancreas increased with time following CFA treatment; 3) a reduced expression of IL-22Rα following CFA treatment; 4) a down-regulation in Reg1 and Reg2 mRNA expression in the pancreas of pre-diabetic mice injected with an IL-22 neutralizing antibody; and 5) an increased islet β-cell DNA synthesis in vitro in the presence of IL-22.We conclude that IL-22 may contribute to the regeneration of β-cells by up-regulating Regenerating Reg1 and Reg2 genes in the islets.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, University of Western Ontario, London, ON Canada.

ABSTRACT

Background: In Type 1 diabetes, the insulin-producing β-cells within the pancreatic islets of Langerhans are destroyed. We showed previously that immunotherapy with Bacillus Calmette-Guerin (BCG) or complete Freund's adjuvant (CFA) of non-obese diabetic (NOD) mice can prevent disease process and pancreatic β-cell loss. This was associated with increased islet Regenerating (Reg) genes expression, and elevated IL-22-producing Th17 T-cells in the pancreas.

Results: We hypothesized that IL-22 was responsible for the increased Reg gene expression in the pancreas. We therefore quantified the Reg1, Reg2, and Reg3δ (INGAP) mRNA expression in isolated pre-diabetic NOD islets treated with IL-22. We measured IL-22, and IL-22 receptor(R)-α mRNA expression in the pancreas and spleen of pre-diabetic and diabetic NOD mice. Our results showed: 1) Reg1 and Reg2 mRNA abundance to be significantly increased in IL-22-treated islets in vitro; 2) IL-22 mRNA expression in the pre-diabetic mouse pancreas increased with time following CFA treatment; 3) a reduced expression of IL-22Rα following CFA treatment; 4) a down-regulation in Reg1 and Reg2 mRNA expression in the pancreas of pre-diabetic mice injected with an IL-22 neutralizing antibody; and 5) an increased islet β-cell DNA synthesis in vitro in the presence of IL-22.

Conclusions: We conclude that IL-22 may contribute to the regeneration of β-cells by up-regulating Regenerating Reg1 and Reg2 genes in the islets.

No MeSH data available.


Related in: MedlinePlus