this lecture is about the pathophysiology of proteinuria and therapy of diabetic nephropathy

1. Diabetic Nephropathy
pathophysiology ..pathology… therapy
Dr. Muhamed Al Rohani,MD

2. Complications of Type 2 Diabetes
Microvascular Complications
Diabetic Retinopathy
Leading cause of
blindness in
working-age adults
Diabetic Nephropathy
Leading cause of
end-stage renal disease
Macrovascular Complications
Stroke
2- to 4-fold increase
in cardiovascular
mortality and stroke
Heart
Disease
Diabetic Neuropathy
Leading cause of
nontraumatic lower
extremity amputations
Peripheral
Vascular Disease
Harris MI. Clin Invest Med. 1995;18:231-239.
Nelson RG, et al. Adv Nephrol Necker Hosp. 1995;24:145-156.
World Health Organization. Diabetes Mellitus Fact Sheet 138. 2002.
ADA. National diabetes fact sheet. Available at:
http://www.diabetes.org/diabetes-statistics/national-diabetes-fact-sheet.jsp.

3. Natural history of DN

4. Definition
progressive rise in urine albumin excretion coupled
with increasing BP and leading to declining GFR
and CKD
Abnormal urine albumin excretion
• >30 mg/24 hours
and/or
diabetic glomerular lesions
and/or
loss of glomerular filtration rate
ADA recommendations, Diabetes Care, January 2012

5. Epidemiology
Diabetic nephropathy affects
approximately one third of
people with type 1 or type 2
diabetes mellitus.
Increase prevalence of DM
USA
4% 1995 – 5.4% 2025
Now: USA 7% (20.8 million)
Worldwide:
2.8 % 171 million 2000 –
4.4% 366 million 2030
DN prevalence
In India: 5.5% and 8.9%
Asian Indians in UK 22.3%
Incident ESRD patients.
Adj: age/gender/race; ref: 2010 ESRD patients.

6. Epidemiology
Type 1 Diabetic

25 - 45% will develop diabetic nephropathy

80- 90% with microalbuminuria will progress to overt diabetic
nephropathy in 5 - 10 years

nearly 100% with gross proteinuria will progress to ESRD in 7 - 10 yrs
Type 2 Diabetic
 50% will have microalbuminuria at the time of presentation with hypertension
 10-20% with microalbuminuria will progress to overt nephropathy.
Risk factors for DN:
Family history
Hypertension
Dyslipidemia
Obese
Male
smokers
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7. Pathology and pathophysiology

8. Pathophysiological stages
Stage increased GFR
Increased filtration pressure as result of increased
intraglolerular pressure
Increased UOP and low s.cra, urea
Pathological change but no clinically evident disease
Proteinuria
Mesangial expansion and increased matrix change in pore
sizes leading to leakage of protein
Starling Foces: increased plasma flow, increased
glomerular capillary hydrostatic pressure
Microhematuria
Ischemic injury of tubules due to construction and
stenosis of efferent arteriole
Decreased GFR
Atrophy and death of nephrons
CKD and ESKD
Loss of compensation mechanisms of nephrons

9. Endothelium
Fenestration (60 – 100 nm)
Glycocalyx (network of proteoglycans
with neg. charge
Endothelial cell injury:
Increased permeability
Impaired nitric oxide production
Upregulation of adhesion molecules
Defects of the glycocalyx:
Decrease of negativity associated
with increased albumin clearance
GBM:
It is 300 – 400 nm tick gel like structure and 90% water
It contains: collagen IV, heparan sulfate proteoglucans, laminin, nidogen
Heparan sulfate reduction correlates with degree of proteinuria
Its degradation is mediated by heparanase
This theory approved in Type 1 and 2 DM but in advanced human cases but not in the
early stage where there is also proteinuria.
Thickening of GBM:
Accumulation of extracellular matrix
Reduction in matrix degradation due to decreased metalloproteinase

10. Systemic HTN, RAS and
hyperinsuliemia
 Efferent vasocostruction
 intraglomerular HTN
Cytokines
High blood glucose
Free radicals
Mesangial cell
expansion
inflammation
Atherosclerosis of efferent arteriole
Mesangial matrix expansion
Fibrin collagens deposition in GBM
Intraglomerular mesangial cells:
Axis holding the edothelial and epithelial cells
Construction and dilatation leading to fenestration change the filtration

11. Hyaline subendothelial deposition
GBM thickening
by collagens : IV
(α3,α4,α5)
Mesangial expansion
By collagens : IV (α1,α2)
V, VI

12. Pores
Barrier
size
Electric charge
Molecular weight
MW: < 40 kDa free to pass
> 100 kDa totally restricted
Albumin mw 69 kDa
Microalbuminuria:
Change in elecric charge
Macroalbuminuria:
Change in elecric charge
Increased pores size
Electric charge:
Anionic ferritin restricted
Cationic ferritin pass to podocyte
Positively charged Dextran
permeable more than neg. or
neutral charged dextran

13. Synthesis and maintenance of the GBM
Counteraction of hydrostatic pressure
Critical membrane of the filtration barrier
(last frontier)
The narrow gaps 30 – 40 nm premeable
for water and solutes
It contains cytoskeleton
The apical membrane contains
podocalyxin, podoplanin and podoendin
which are responable of the negative
charge
Podocytopenia:
Loss of negative charge (loss of podocalyxin)
Change in the pores size due to damage in the diagram integrity
Causes of reduced number of podocytes:
Podocyte detacement
Podocyte apoptosis
Inability to proliferate and restore podocyte number
Silt diaphragm abnormalities:
Abnormalities of nephrin
Foot process widening and effacement

14. Pathological classification of DN
Class
I
Description
Inclusion Criteria
Biopsy does not meet any of the criteria mentioned below
Mild or nonspecific LM changes and for class II, III, or IV
EM-proven GBM thickening
GBM > 395 nm in female and >430 nm in male individuals
9 years of age and older, Podocyte hypertrophy
IIa
Biopsy does not meet criteria for class III or IV
Mild mesangial expansion
IIb
Mild mesangial expansion in >25% of the observed
mesangium
Biopsy does not meet criteria for class III or IV
Severe mesangial expansion
III
Severe mesangial expansion in >25% of the observed
mesangium
Nodular sclerosis (Kimmelstiel–
Wilson lesion)
Biopsy does not meet criteria for class IV
At least one convincing Kimmelstiel–Wilson lesion
IV
Advanced diabetic
glomerulosclerosis
Global glomerular sclerosis in >50% of glomeruli
Lesions from classes I through III

16. Mechanisms of proteinuria
Site of injury
Glomerular hemodynamics
glomerular endothelial cell
GBM
podocyte
Glomerular hyperfiltration
Endothelial cell injury Diminished Hyperglycemia< AGE, ROS Endothelial cell injury or
endothelial glycocalyx
enzymatic cleavage
Altered VEGF signaling
Podocyte injury or loss
Irregular thickening
Decreased negative charge
Podocytopenia
Loss of slit diaphragm integrity
Foot process widening and
effacement
Loss negative charge
proximal tubule
Afferent arteriole vasodilatation
Efferent arteriole vasoconstriction
glomerular capillary pressure
Decrease protein reabsorption
production and/or degradation of extracellular matrix
proteins
production and/or degradation of HSPG
Detachment, apoptosis, lack of proliferation
Decrease or changes in subcellular localization of nephrin
Disrupted actin cytoskeleton
Loss of slit diaphragm integrity
Impaired podocyte GBM interaction
Podocalyxin
Tubular injury and interstitial fibrosis
AGE, advanced glycosylation end products; HSPG, heparan sulfate proteoglycan; ROS, reactive
oxygen species; VEGF, vascular endothelial growth factor.

17. Proteinuria Is an Independent Risk Factor
for Mortality in Type 2 Diabetes
1.0
Normoalbuminuria
(n=191)
Survival
(all-cause mortality)
0.9
Microalbuminuria
(n=86)
0.8
0.7
Macroalbuminuria
(n=51)
0.6
0.5
0
1
2
3
Years
Gall et al. Diabetes. 1995;44:1303.
4
5
6

19. Factors affecting urinary albumin excretion
Increases AER
Decreases AER
 Strenuous exercise
 Poorly controlled DM
 Heart failure
 UTI
 Acute febrile illness
 Uncontrolled HPT
 Haematuria
 Menstruation
 Pregnancy
 NSAIDs
 ACE inhibitors

21. SCREENING FOR
NEPHROPATHY
WHEN: Type 1 - annually after puberty and 5 years of DM
Type 2 - at diagnosis and then annually
WHAT: random urine ACR;
and random urine dipstick
Suspicion of
nondiabetic
renal disease?
No
Normal
< 2.0 mg/mmol men
< 2.8 mg/mmol women
Rescreen in 1 year
Check ACR results
Microalbuminuria
2.0 - 20 mg/mmol men
2.8 - 28 mg/mmol women
Only 1 abnormal ACR:
Repeat screen in 1 year
1/26/2014
Up to 2 repeat random urine ACRs
performed 1 week to 2 months
apart
Yes
Workup or referral for
nondiabetic renal
disease
Macroalbuminuria
> 20 mg/mmol men
> 28 mg/mmol women
Diabetic nephropathy
diagnosed
Any 2 abnormal out of 3
ACRs: Diabetic
nephropathy diagnosed
21

22. Stages of Renal Involvement According to
the Urinary Albumin Level
SPECIMEN COLLECTED
First voided morning specimen
Albumin Excretion
24hr collection
(mg/24h)
Timed collection
(μg/min)
Normoalbuminuria
<30
Microalbuminuria
Overt proteinuria
Urine Albumin
concentration
(mg/l)
Urine
Albumin:Creatinine
ratio* (mg/mmol)
<20
<20
<3.5 (F)
<2.5 (M)
30-300
20-200
20-200
3.5 to 35 (F)
2.5 to 25 (M)
>300
>200
>200
>35 (F)
>25 (M)

23. TREATMENT OF NEPHROPATHY
Already on ACE inhibitor?
Choose 2nd line therapy: ACE or
ARB and add non-DHP CCB
YES
NO
On first-line nephropathy
drug?
NO
Add first-line drug;
Recheck ACR in 2
weeks to 2 months
YES
YES
NO
ACR normal?
Yes
First line drug at
maximum dose?
NO
Titrate up; recheck ACR
in
2 weeks to 2 months
Remeasure ACR in 1 year
First line drugs:
Type 1- ACE inhibitor
Type 2 with Cr Cl > 60 mL/min - ACE inhibitor or ARB
Type 2 with Cr Cl 60 mL/min - ARB
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24. Table 2. Recommendations for the Comprehensive
Management of T2DM Patients with CKD
Factor
Recommendations
Lifestyle factors
diet, exercise, smoking,and alcohol intake
Blood glucose
Treatment goal:
HbA1c <6.5%
Preprandial plasma glucose 90-130 mg/dl
Postprandial plasma glucose <180 mg/dl
Blood pressure
Goal ≤130/80 mm Hg
Use maximal tolerated dose of ACE inhibitor or ARB before
adding a second agent
Cholesterol
Goal <4.0 mmol/L for total cholesterol and <2.0 mmol/L for
LDL-C
Consider use of a statin irrespective of baseline lipid values for
the secondary prevention of cardiovascular disease
Platelets
Consider use of low dose aspirin for the secondary prevention
of cardiovascular disease
Monitoring
Annual monitoring of eGFR and ACR

25. The glycemic control studies
A1c Target : Outcome
UKPDS
10 yrs
> 7%
The clinical lesson from the UKPDS follow-up studies is that,
although the risks of complications of hypertension might
be mitigated with initiation of treatment even after a
prolonged elevation of blood pressure, it is particularly
necessary to treat hyperglycemia appropriately from the
outset of type 2 diabetes.
ADVANCE study
Intensive Blood
Glucose Control
and Vascular
Outcomes in
Patients with Type
2 Diabetes
6.5%
A strategy of intensive glucose control, involving gliclazide
(modified release) and
other drugs as required, that lowered the glycated
hemoglobin value to 6.5% yielded a 10% relative reduction
in the combined outcome of major macrovascular and
microvascular events, primarily as a consequence of a 21%
relative reduction in nephropathy.
ACCORD Study:
Long-Term Effects
of Intensive
Glucose Lowering
on Cardiovascular
Outcomes
<6%
As compared with standard therapy, the use of intensive
therapy for 3.7 years to target a glycated hemoglobin level
below 6% reduced 5-year nonfatal myocardial infarctions
but increased 5-year mortality. Such a strategy cannot be
recommended for high-risk patients with advanced type 2
diabetes.

26. KDIGO recommendation for proteinuria
ACE inhibitors and ARBs are effective in slowing progression of kidney disease characterized by
microalbuminuria in hypertensive patients with type 1 or type 2 diabetes. (Moderate)
ACE inhibitors, ARBs, and nondihydropyridine calcium channel blockers have a greater antiproteinuric
effect than other antihypertensive classes in hypertensive patients with DKD. (Strong)
Dihydropyridine calcium channel blockers, when used to treat hypertension in the absence of ACE
inhibitors or ARBs, are less effective than other agents in slowing progression of DKD. (Strong)
•
ARBs are more effective than other
antihypertensive classes in slowing
progression of kidney disease characterized
by macroalbuminuria in hypertensive
patients with type 2 diabetes. (Strong)
•
•
ACE inhibitors are more effective than
other antihypertensive classes in slowing
progression of kidney disease characterized
by macroalbuminuria in hypertensive
patients with type 1 diabetes. (Strong)
ACE inhibitors may be more effective than
other antihypertensive classes in slowing
the progression of kidney disease
characterized by macroalbuminuria in
hypertensive patients with type 2 diabetes.
(Weak)

27. ACE Inhibitors can prevent progression of renal
failure
Risk reduction is 51%
Reduce microalbuminuria
All causes of mortality
Normotensive Type 2 Diabetics
400
110
Proteinuria
350
320
% Initial GFR
105
Placebo
(mg/day)
100
280
Enalapril
240
95
200
90
160
Placebo
Enalapril
85
120
80
80
0
1
2
3
Years
Ann Intern Med 118 577-581.1993
J Am Soc Nephrol 2006
4
5
6
0
1
2
3
Years
4
5
6

28. Incidence of Progression to Diabetic Nephropathy during Treatment with 150 mg
of Irbesartan Daily, 300 mg of Irbesartan Daily, or Placebo in Hypertensive
Patients with Type 2 Diabetes and Persistent Microalbuminuria.
Parving H et al. N Engl J Med 2001;345:870-878.

29. Olmesartan for the Delay or Prevention of Microalbuminuria in
Type 2 Diabetes in 4447 patients
Conclusion:
• Olmesartan was associated with a delayed onset of microalbuminuria, even though
blood-pressure control
• The higher rate of fatal cardiovascular events with olmesartan among patients with
preexisting coronary heart disease is of concern.
Combined Angiotensin Inhibition for the Treatment of Diabetic
Nephropathy in 1448 patients
Combination therapy with an ACE inhibitor and an ARB was associated with an increased
risk of adverse events among patients with diabetic nephropathy.
There was no benefit with respect to mortality or cardiovascular events. Combination
therapy increased the risk of hyperkalemia and acute kidney injury.

30. Metformin in Patients with T2DM and CKD
• The recommendation of the ADA/EASD
metformin can be used
– down to an eGFR of 30 mL/min/1.73 m2,
– the dose of metformin should be reduced when eGFR
is less than 45 mL/min/1.73 m2.
– Kidney function should be checked regularly (every 6
months)
– discontinued if eGFR falls below 30 mL/min/1.73 m2.
– prescribed with caution in patients with an eGFR less
than 45 mL/min/1.73 m2, which is rapidly
deteriorating.
– All patients should be warned that if they develop a
condition that can lead to dehydration.

32. KDIGO lipid control in DM
•
•
•
•
Target LDL-C in people with diabetes and CKD stages 1-4 should be < 100 mg/dL;
<70 mg/dL is a therapeutic option. (B)
People with diabetes, CKD stages 1-4, and LDL-C > 100 mg/dL should be treated
with a statin. (B)
Treatment with a statin should not be initiated in patients with type 2 diabetes on
maintenance hemodialysis who do not have a specific cardiovascular indication for
treatment. (A)
Atorvastatin treatment in patients with type 2 diabetes on maintenance treatment
does not improve cardiovascular outcomes. (Strong)

33. Other oral antidiabetic drugs :
DPP-4 inhibitors:
Choices of antidiabetic agents for
patients with type 2 diabetes mellitus
(T2DM) and chronic kidney disease
(CKD) are limited. Available data
suggest that the use of dipeptidyl
peptidase-4 (DPP-4) inhibitors may
be safe in patients at various stages
of renal insufficiency. However,
except for linagliptin, dosage
adjustment is necessary.
patients with moderate renal impairment
(defined in the label as a creatinine
clearance ≥ 30 to < 50 ml/min). In
severe renal impairment (creatinine
clearance < 30 ml/min) or end-stage
renal disease requiring dialysis, the
dose is further reduced to 25 mg
once daily.
Gliclazide
In patients with mild to moderate renal
insufficiency the same dosing
regimen can be used as in patients
with normal renal function with
careful patient monitoring. These
data have been confirmed in clinical
trials.
glimepiride
A multiple-dose titration using doses
ranging from 1 mg to 8 mg daily for 3
months. Baseline creatinine
clearance ranged from 10–60
mL/min.

34. Insulin
Metabolism of insulin: 30–
80% of systemic insulin in
the kidney
40–50% of the endogenous
insulin metabolized by the
liver
Insulin effect on the kidney :
Na reabsorption Increase
glucose and phosphate
higher risk of hypoglycaemia
Intensive glucose control with
HbA1c around 7% is
associated with:
Reduction of microalbuminuria
by 39% and
marcroalbuminuria by 54%

35. Study of Heart and Renal Protection (SHARP): randomized trial to assess the effects of
lowering low-density lipoprotein cholesterol among 9,438 patients with chronic kidney
disease.
RESULTS:
A total of 9,438 CKD patients were randomized, of whom 3,056 were on dialysis. Mean age
was 61 years, two thirds were male, one fifth had diabetes mellitus, and one sixth had
vascular disease. Compared with either placebo or simvastatin alone, allocation to ezetimibe
plus simvastatin was not associated with any excess of myopathy, hepatic toxicity, or biliary
complications during the first year of follow-up. Compared with placebo, allocation to
ezetimibe 10 mg plus simvastatin 20 mg daily yielded average LDL cholesterol differences of
43 mg/dL (1.10 mmol/L) at 1 year and 33 mg/dL (0.85 mmol/L) at 2.5 years. Follow-up is
scheduled to continue until August 2010, when all patients will have been followed for at
least 4 years.
CONCLUSIONS:
SHARP should provide evidence about the efficacy and safety of lowering LDL
cholesterol with the combination of ezetimibe and simvastatin among a wide range
of patients with CKD
(SHARP; Lancet. 2011;377:2181-2192).

36. Bardoxolyne methyl, has been shown to significantly improve the creatinine GFR and
cystatin C GFR in patients with DKD after only 4 weeks
(Schwartz, Denham, Hurwitz, Meyer, & Pergola, 2009).
Recent landmark phase 2 trial of 227 adults with CKD and type 2 DM demonstrated that bardoxolone
methyl ( 75 mg is the optimal dose) improved GFR by at least 8.2 +/-1.5 ml/min over placebo after 24
weeks of treatment and that this effect was maintained after a year of therapy.
(Pergola, et al., 2011).
BUT
Bardoxolone methyl did not improve urinary albumin excretion.
The results in 3 phase study (BEACON)
were disappointing because of elevated rate of CVD including HTN, HF, and increased heart rate
PIRFENIDONE:
Paricalcitol
Ruboxistaurtin
Allopurinol

37. Thank you
The End