hypertension secondary to neonatal hyperleptinaemia Anne-Maj - - PowerPoint PPT Presentation

Molecular mechanisms of renal dysfunction and hypertension secondary to neonatal hyperleptinaemia

Anne-Maj Samuelsson KCL Division of Women’s Health Note: for non-commercial purposes only

Maternal obesity imprint cardiovascular, renal and metabolic dysfunction in the offspring

Maternal Causes Hyperinsulinaemia Adipokine dysregulation (leptin↑) Baroreflex impairment Psychological stress Oxidative stress Inflammation Renal afferent nerve activation Fetal Causes Sympathetic nervous system activation Physiopathologicalogical mechanism Renin-angiotensin system activation EARLY ORIGIN OF HYPERTENSION/ RENAL DYSFUNCTION Endothelial dysfunction Oxidative stress Nephrogenesis Inflammation Nephron hyperfiltration

Maternal Obesity and Neonatal Leptin

Origin of SNA mediated hypertension

Kirk et al 2009, PlosOne, Samuelsson et al 2013, Hypertension

A. Neonatal leptin surge

• B. ARC pSTAT3

2 4 6 8 10 12 14 OffCon OffOb Delta MAP mmHg) *

500 1000 1500 2000 2500 3000

• 2.30 -

3.30 - 4.16 Number of pSTAT3

• ir Cells/mm

2 * Bregma (mm)

OffOb OffCon

• 2.30 -

3.30 - 4.16

• *

Bregma (mm)

NEONATAL LEPTIN

Early Onset Hypertension Sympathetic Overactivity Hyperphagia Cardiac Dysfunction Renal Function?

Renal dysfunction in animal models

Maternal UN/GDM- Reduced nephron number, increased Na reabsorption, activation of RAS and oxidative stress Maternal HF diet -Salt-induced hypertension, Na-ATPase activity, no serological evidence Renal proximal tubule Na+ reabsorption extracellular volume BP

• Na-ATPase
• Na+/H+exchanger isoform 3 (NHE3)-PT
• Na+-K+-Cl- cotransporter (NKCC2a and b) –TAL

Regulation of sodium homeostasis

• Reactive oxygen species (ROS)
• Ang II
• Cyclo-oxygenase 2 (COX2)
• RSNA

High RSNA Kidney ischemia Intrarenal RAS Hyperfiltration Renal disease

(Merlet-Benichou C et al 1994)(Jones SE et al 2001)(Gilbert JS et al 2005)(Armitage 2005) (Rudyk et al 2000)

To investigate if exposure to elevated leptin in early postnatal life may permanently influence renal function due to altered renal sympathetic nerve activation, oxidative status, and renal vascular smooth muscle responses

Aim

Study Design

Sprague-Dawley rats

Neonatal leptin (3μg/g, L-Tx) Neonatal saline (S-Tx)

F0 F1

(PD9-PD14)

F1

(1-2 month) Telemetry surgery Renal Denervation (RD and SH) Renal Function before and after RD Renal Myography

F1

(6 month) Renal Function Salt loading

C57Bl/6 mice

Neonatal leptin (3μg/g, L-Tx) Neonatal saline (S-Tx)

F0 F1

(PD9-PD15)

F1

(6 month) Telemetry surgery Renal Function Renal QPCR

Hypertension-Unilateral Renal Denervation

*P<0.001, **P<0.01, *P<0.05 (repeated ANOVA t test). Data are presented as mean ± SEM; n=4-8 per group.

1 month old male rats 6 month old male mice

5 10 15 20 25 90 100 110 120 130 140

Time (Hours) MAP (mmHg)

S-Tx L-Tx

*

5 10 15 20 25 80 90 100 110 120 S-Tx L-Tx Time (min) MAP (mmHg)

**

5 10 15 20 25 80 90 100 110 120 S-Tx SH S-Tx RD Time (hours) MAP (mmHg)

Renal Denervation

5 10 15 20 25 80 90 100 110 120 130 L-Tx SH L-Tx RD Time (hours) MAP (mmHg)

*** **

Renal Artery Myography in the early-hypertensive phase (1 month old)

Noradrenaline

• 10
• 9
• 8
• 7
• 6
• 5
• 4
• 3

25 50 75 100 SNP log [M] Relaxation (%) S-Tx L-Tx

Sodium nitropruisside

• 9
• 8
• 7
• 6
• 5
• 0.5

0.0 0.5 1.0 1.5 2.0 NA log [M] Tension (mN/mm) S-Tx L-Tx pEC50 L-Tx, 5.8±0.1 S-Tx. 5.4±0.1,P<0.05 ECmax L-Tx, 1.7±0.1 S-Tx,1.1±0.1, P<0.01

Renal Denervation

• 8
• 7
• 6
• 5
• 0.5

0.0 0.5 1.0 1.5 2.0 NA log [M] Tension (mN/mm) L-Tx-RD L-Tx-SH pEC50 L-Tx-SH, 6.0±0.1 L-Tx-RD, 5.6±0.1, P<0.05 ECmax L-Tx-SH, 1.8±0.1 L-Tx-RD, 1.2±0.1,P<0.05 pIC50 L-Tx, 6.2±0.1 S-Tx. 6.4±0.1,ns ICmax L-Tx, 49±9 S-Tx, 67±6, P<0.01

• 10
• 9
• 8
• 7
• 6
• 5
• 4
• 3

25 50 75 100 SNP log [M] Relaxation (%) pIC50 L-Tx-SH, 6.3±0.1 L-Tx-RD. 6.4±0.1,ns ICmax L-Tx-SH, 48±3 L-Tx-RD, 62±2, P<0.05 L-Tx-RD L-Tx-SH

Data are presented as mean ± SEM; n=4-8 per group, t-test.

Renal Function and Salt Challenge

20 40 60 S-Tx L-Tx

Water intake (ml/24)

* * * * ** *

10 20 30 40 50 S-Tx L-Tx Urine volume (ml/24h) 10 20 30 40 50 S-Tx L-Tx Albuminuria (mg/ml)

* * *

1 2 3

Creatinine Clearance (ul/min/100gBW)

* * *

S-Tx L-Tx

Data are presented as mean ± SEM; n=4-8 per group,*P<0.05, t-test.

Intrarenal expression of RAS, oxidative stress component and sodium transporters at established-hypertension phase

Renin Angiotensin system Oxidative stress and Fibrosis

500 1000 1500 2000 S-Tx L-Tx Normalised mRNA

* ** * * ** ** **

50 100 150 200 Normalised mRNA

500 1000 1500 2000 2500 S-Tx L-Tx Normalised mRNA

** ** * * *

Data are means±SEM. N=5-6. **p<0.01,*p<0.05 vs S-Tx using t-test

Na/H and Na/K/Cl cotransporters

5000 10000 15000 S-Tx L-Tx Normalised mRNA

*

CONCLUSION

Neonatal leptin treatment (L-TX) led to



Hypertension



MAP before obesity.



Enhanced contractile response in 2 nd order renal arteries



Renal nerve denervation of left kidney showed beneficial effects (normalised the blood pressure and artery function) illustrating the important role of renal sympathetic overactivity in this model



Renal parameters during early hypertensive phase (1 month) showed decreased creatinine clearance. L-Tx rats had significant albuminuria which was totally suppressed by renal denervation.



The renal physiology during established hypertension phase (6 months) showed significant decrease in creatinine clearance, accompanied by an expanded plasma volume and urine albuminuria.

CONCLUSION II

Neonatal leptin treatment (L-TX) led to



Altered renal RAS, sodium transport and oxidative stress markers during established-hypertension phase



Increased renal RAS, Cox-2 and Nox-4 may affect renal microvasculature and Na+ sodium reabsorption via Na+ ATPase contributing further to the permanent hypertensive state.

Page 12

Thanks to

King’s College London Katharina Tilgner Shona Kirk Joaquim Pombo Vanessa Alderman Sarah Wylie Dr Paul Taylor Prof Clive Coen Prof Lucilla Poston