1. in the pancreatic beta-cell
Effects of gliclazide
on oxidative stress
in the pancreatic beta-cell
Piero Marchetti
University of Pisa

2. Defining T2DM

3. Defining T2DM …varying degrees of insulin resistance
and insulin secretory deficiency

4. Defining T2DM …varying degrees of insulin resistance
and insulin secretory deficiency

5. The natural history of T2DM

6. T2DM: the fundamental factor is…

7. T2DM: the fundamental factor is…
…the beta-cell!

8. To be discussed
The beta-cell in normal conditions and in type 2 diabetes
The importance of oxidative stress induced beta-cell damage
The role of gliclazide

9. To be discussed
The beta-cell in normal conditions and in type 2 diabetes
The importance of oxidative stress induced beta-cell damage
The role of gliclazide

10. Islet of Langerhans ~ 3,000 cells 75% Beta cells 200 µm
25% non-Beta cells
200 µm
Micrograph: Lelio Orci, Geneva
Presented by Pr Philippe Halban
at the 1st Amsterdam Diabetes Meeting, March 30-April 1, 2006

11. The normal beta-cell ~ 10,000 granules 10 µm
Presented by Pr Philippe Halban
at the 1st Amsterdam Diabetes Meeting, March 30-April 1, 2006
Micrograph: Lelio Orci, Geneva

12. The normal beta-cell
Half-life of ~30 days

13. The normal beta-cell Half-life of ~30 days
Apoptosis is the major mechanism of death

14. The normal beta-cell Half-life of ~30 days
Apoptosis is the major mechanism of death
normal

15. The normal beta-cell Half-life of ~30 days
Apoptosis is the major mechanism of death
normal
apoptotic

16. The normal beta-cell Half-life of ~30 days
Apoptosis is the major mechanism of death
New beta-cells by
replication
neogenesis

17. The beta-cell in T2DM Butler P et al, Diabetes 2003
Del Guerra S et al, Diabetes 2005

18. Summary1 Compared to the normal situation, in T2DM there is:
decreased beta-cell mass
reduced insulin secretion function (in particular in response to glucose)

19. To be discussed
The beta-cell in normal conditions and in type 2 diabetes
The importance of oxidative stress induced beta-cell damage
The role of gliclazide

20. Beta-cell oxidative stress in human T2DM beta-cells

21. Beta-cell oxidative stress in human T2DM beta-cells

22. Beta-cell oxidative stress in human T2DM beta-cells
8-OHdG immunostaining

23. Beta-cell oxidative stress in human T2DM beta-cells

24. Beta-cell oxidative stress in human T2DM beta-cells

25. Beta-cell oxidative stress in human T2DM beta-cells

26. Beta-cell oxidative stress in human T2DM beta-cells

27. Beta-cell oxidative stress in human T2DM beta-cells

28. Beta-cell oxidative stress in human T2DM beta-cells
gene expression
Marchetti P et al, JCEM 2004

29. Glucose Toxicity
Robertson RP, JBC 2004

30. Summary2
In T2DM, there is increased oxidative stress at the beta-cell level, which contributes to:
mass reduction
insulin secretion defects

31. The beta-cell in T2DM
normal

32. The beta-cell in T2DM Genetic factors Acquired factors normal
(glucotoxicity, lipotoxicity,
IAAP, others)
normal

33. The beta-cell in T2DM Genetic factors Acquired factors normal
(glucotoxicity, lipotoxicity,
IAAP, others)
normal
Type 2 diabetes

34. The beta-cell in T2DM Genetic factors Acquired factors
(glucotoxicity, lipotoxicity,
IAAP, others)
normal
WHAT’S THE ROLE OF
SULPHONYLUREAS?
Type 2 diabetes

35. To be discussed
The beta-cell in normal conditions and in type 2 diabetes
The importance of oxidative stress induced beta-cell damage
The role of gliclazide

36. The role of sulphonylureas
Some studies have reported increased sulphonylurea-induced beta-cell apoptosis in-vitro

37. The role of sulphonylureas
Some studies have reported increased sulphonylurea-induced beta-cell apoptosis in-vitro
ctrl nategl glibencl
Maedler K et al, JCEM 2005

38. The role of gliclazide
Diabetes Metab Res Rev 2007

39. The role of gliclazide
Human islets were prepared by collagenase digestion and density gradient purification
number
age (yrs)
gender
BMI (Kg/m2) 16
57.9 ± 5.7
10M 6F
24.6 ±
3.2

40. Density gradient purification
Preparation of isolated human islets
Collagenase digestion
Density gradient purification

41. The role of gliclazide Culture for 5 days in:
continuous normal glucose medium (NG, 5.5 mM) or high (HG, 16.7 mM) and normal glucose media, alternating every 24h
with or without 10 µmol/l glibenclamide (GLIB) or 1/10 µmol/l gliclazide (GLICL)

42. The role of gliclazide Assessment of:
acute glucose-stimulated insulin secretion
beta-cell apoptosis and mitochondrial morphology (electron microscopy)
gene expression
protein expression
oxidative stress (nitrotyrosine concentration)

43. The role of gliclazide
Stimulation index (% of controls) *

44. The role of gliclazide
Stimulation index (% of controls) * * * *

45. The role of gliclazide
Beta-cell apoptosis (%) * *

46. (antioxidant properties)
The role of gliclazide
(antioxidant properties)

47. (antioxidant properties)
The role of gliclazide
(antioxidant properties)
Scott NA et al, Eur J Pharmacol 1991
Noda Y et al, Res Commun Mol Pathol Pharmacol 1997
Jennings PE and Belch JJ, Metabolism 2000
Renier G et al, J Diabetes Complications 2000
Fava D et al, Diabet Med 2002
Onozato ML et al, Kidney Int 2004
Alper G et al, Endocr Res 2005
Li L and Renier G, Metabolism 2006

48. The role of gliclazide

49. The role of gliclazide
Nitrotyrosine (ng/ml) * **

50. The role of gliclazide

51. The role of gliclazide
Ctrl
H2O2

52. The role of gliclazide
Ctrl
H2O2
H2O2+GLICL
H2O2+GLIB

53. The role of gliclazide
% viability
H2O2 (µmol/l)

54. Summary3
Gliclazide has several beneficial effects on beta-cells, including:
better survival
improved function

55. Conclusions
The pancreatic beta-cell is central to the development and progression of diabetes
Several factors and mechanisms contribute to beta-cell damage in T2DM, including increased oxidative stress
Gliclazide has protective effects on the beta-cell, due, at least in part, to its antioxidant properties
Additional long term, prospective studies in patients are needed to confirm the in-vitro data

56. in the pancreatic beta-cell
Effects of gliclazide
on oxidative stress
in the pancreatic beta-cell
Thank you very much
for your attention!!!
Piero Marchetti
University of Pisa