Renal lesions aggravation are prevented by
low doses of sitagliptin in a rat model of
type 2 diabetes
Cristina Mega, Helena Vala, Jorge Oliveira, Rosa Fernandes, Filipa Mascarenhas-Melo,
Belmiro Parada, Rui Pinto, Frederico Teixeira, Flávio Reis, Edite Teixeira de Lemos
Major complications of Type 2 Diabetes Mellitus (T2DM)
Macrovascular
Heine RJ, Spijkerman AM. 2006.
Microvascular
Cardiovascular
diseases
Retinopathy
Neuropathy
Nephropathy
Diabetic Nephropathy – A Major Diabetic Complication
• Diabetic nephropathy is a major microvascular complication of T2DM
• Incidence of T2DM is rapidly increasing, as well as the prevalence of
chronic kidney disease (CKD), resulting from these diabetic
complications
• In different regions of the World, it accounts for almost one-third of all
cases of end-stage renal disease (ESRD)
Diabetes
remains the single
most important cause of kidney failure
Therapeutic Goals in Type 2 Diabetes Mellitus (T2DM)
Prevention of Diabetes-Induced
dysmetabolism and associated
vascular complications
Blood Glucose levels
Insulin
secretion/action
Therapeutic Goals in Type 2 Diabetes Mellitus (T2DM)
Until now, anti-diabetic drugs were
able to
Hyperglycaemia
None were able to
preserve β-cells
Anti-diabetic drugs
Sitagliptin

Knowing that



incretin defect is a major contributor to β-cell
dysfunction
incretins stimulate release of insulin by β-cells
incretin inhibits glucagon release by α-cells
and that in T2DM the incretin effect is decreased
New anti-diabetic drugs, focus on the increase of
incretin levels in diabetic patients, like Sitagliptin
a dipeptidyl peptidase-4 (DPP-4) inhibitor and one
of the best known incretin enhancers
Sitagliptin targets 2 physiologic
glucose-lowering actions with a single oral agent
Improves
24 h
glycaemic
control
Incretin hormones GLP-1 and
GIP are released by the
intestine throughout the day
Glucose dependent
Their levels increase in
response to a meal and are
found to be reduced in
Diabetes
GLP-1
Beta cells
 Insulin
(GLP-1 and GIP)
GIP
2-4
minutes
DPP-4
enzyme
X
Inactive
GLP-1
Inactive
GIP
 Glucagon
Alpha cells
Glucose
uptake by
peripheral
tissues
(GLP-1)
SITAGLIPTIN allows
for a longer
circulation life for
incretins
Glucose
production
by liver
B
L
O
O
D
G
L
U
C
O
S
E
Inhibition of DPP-4 activity, by incretin enhancers, such
as Sitagliptin (Known Effects)
Improve glycaemic control,
in diabetic patients
Preserving
pancreatic function
by prolonging the actions of incretin hormones
but the real impact of low-dose sitagliptin treatment on
diabetic nephropathy remains to be elucidated
Assess the effects
SITAGLIPTIN
?
Prevention of Diabetes-Induced
dysmetabolism and microvascular
complications – Diabetic Nephropathy
AIM:
Evaluate the effects of chronic (6 weeks) inhibition of DPP-4 by low doses of
sitagliptin, in the ZDF rat, an animal model of T2DM, on progression of
renal lesions
Animals and experimental design:
♂ Zucker Diabetic Fatty
(ZDF fa/fa) (n=16)
Age: 20 weeks
Controls: their lean littermates
(ZDF +/+) (n=8)
Age: 20 weeks
Divided in 2 subgroups (n = 8 rats)
treated with:
- Sitagliptin 10 mg/kg/BW/day
or
- Vehicle (orange juice)
SID (6:00 PM), for 6 weeks
Sample Collection and Preparation
Blood and tissues - collected at 20 weeks (Ti) and at 26 weeks (Tf)
Renal specimens were paraffin-embedded and the 3 µm thick sections
stained for routine histopathological diagnosis with haematoxylin and
eosin (HE) and Periodic Acid of Schiff (PAS)
All samples were examined by light microscopy using a Zeiss Axioplan
2 microscope
Histomorphological Evaluation
Mesangial expansion
GBM thickening
Capsule of Bowman thickening
Nodular sclerosis
Glomerulosclerosis
Atrophy
Hyalinosis of the vascular pole
R
E
N
A
Arteriolar hyalinosis
Arteriosclerosis.
Inflammation
Hyaline cylinders
Tubular basement membrane irregularity
Tubular calcification
Interstitial fibrosis/tubular atrophy (IFTA)
L
L
E
S
I
O
N
S
Semi-quantitative scoring of lesions
0 = absent
1 = mild
2 = moderate
3 = severe
Severity
+
0 = < 25%
1 = 25 - 50%
2 = 50 - 75%
3 = > 75 %
(Except IFTA)
Extension
All lesions were evaluated on the total tissue on the slide.
Scored in single blind fashion
Scoring of lesions
VASCULAR
IFTA
Arteriolar hyalinosis
0 = absent
0 = absent
1 = < 25%,
1 = one arteriole with hyalinosis was present
2 = 25 - 50%
3 = > 50%
(of affected area)
2 = more than one arteriole was observed
Arteriosclerosis
0 = no intimal thickening was present
1 = intimal thickening was < than media thickness
2 = intimal thickening > than media thickness
RESULTS
Sitagliptin Reduced Kidney Oxidative Stress
(Positive Impact on Lipid Peroxidation Levels in renal tissues)
Treated
Diabetic
Rats
Ti (20 wks)
Tf (26 wks)
Sitagliptin Reduced Kidney Dysfunction
(Decrease of Blood Urea Nitrogen – BUN)
Effect of Sitagliptin on Glomerular Lesions
Diabetic ZDF (Sita-treated vs Untreated)
UNTREATED
SITA-TREATED RATS
50µm
50µm
25µm
25µm
Effect of Sitagliptin on Glomerular Lesions
Diabetic ZDF (Sita-treated vs Untreated)
UNTREATED
SITAGLIPTIN-TREATED
50µm
50µm
25µm
25µm
mnng
Effect of Sitagliptin on Glomerular Lesions
Diabetic ZDF (Sita-treated vs Untreated)
Effect of Sitagliptin on Tubulointersticial Lesions
Diabetic ZDF (Sita-treated vs Untreated)
UNTREATED
SITAGLIPTIN-TREATED
50µm
50µm
50µm
25µm
All Tubulointerstitial Lesions improved
Diabetic ZDF (Sita-treated vs Untreated)
The Improvement of Glomerular & Tubulointerstitial Lesions
Diabetic ZDF (Sita-treated vs Untreated)
25µm
25µm
Effect of Sitagliptin on Vascular Lesions
Diabetic ZDF (Sita-treated vs Untreated)
UNTREATED
SITA-TREATED ANIMALS
25µm
25µm
Effect of Sitagliptin on Vascular Lesions
Diabetic ZDF (Sita-treated vs Untreated)
UNTREATED
SITAGLIPTIN-TREATED
25µm
25µm
Effect of Sitagliptin on Vascular Lesions
Diabetic ZDF (Sita-treated vs Untreated)
UNTREATED
SITAGLIPTIN-TREATED
25µm
25µm
Effect of Sitagliptin on Vascular Lesions
Diabetic ZDF (Sita-treated vs Untreated)
UNTREATED
SITAGLIPTIN-TREATED
25µm
25µm
Effect of Sitagliptin on Vascular Lesions
Diabetic ZDF (Sita-treated vs Untreated)
Conclusions
In an animal model of T2DM, a 6 week once daily treatment with a low dose
of Sitagliptin promoted:
REGULATION OF DIABETIC
DISMETABOLISM
Hyperglycaemia
Hypertriglyceridaemia
Has the effect in
IMPROVEMENT OF
DIABETIC
NEPHROPATHY
- Glomerulosclerosis
RENAL FUNCTION
Oxidative stress
Blood Urea Nitrogen
- Tubulointerstitial lesions
- Vascular lesions
Conclusions
Sitagliptin was able to delay the development of diabetic
nephropathy in this model of T2DM, viewed by reduction of renal
lesions
This effect might be, at least, partially due, to its benefits on
correction
of
diabetes
dysmetabolism
(hyperglicaemia,
dyslipidaemia and insulin production/sensitivity), as well as due to
a favorable impact on kidney lipid peroxidation
The prevention of diabetic nephropathy evolution might
represent a key step forward in the management of T2DM
and these serious complications
Muito obrigada!
Paljon kiitoksia
Thank you very much!
Cristina Mega, Helena Vala, Jorge Oliveira, Rosa Fernandes, Filipa Mascarenhas-Melo,
Belmiro Parada, Rui Pinto, Frederico Teixeira, Flávio Reis, Edite Teixeira de Lemos
This presentation was supported by the Polytechnic Institute of Viseu, Portugal