the rise of fgf23 from mendelian obscurity to mainstream...

The Rise of FGF23 from MendelianObscurity to Mainstream Cardiovascular Notoriety: A Case-Study in Translational Research

Myles Wolf, MD, MMScUniversity of Miami Miller School of Medicine

Disclosures: Abbott (Honoraria), Amgen (Consultant), Genzyme(Honoraria), Luitpold (Consultant), Shire (Research support)

Importance of PhosphatePhospholipid bilayersCell signalingGlycolysisATPUnloading O2 (2,3-BPG)

2

3

Intestinal Phosphate AbsorptionLinear absorption, nonsaturable function of intakeApproximately 60-75% of intakePrimarily in small intestine1,25(OH)2D3 stimulates absorption via NaPi2bMost phosphate absorption vitamin D independent

via paracellular transport

Phosphate Balance

Hruska KA et al. Kidney International (2008) 74, 148–157

Prie D et al. Kidney International (2009) 75, 882-889.

Renal Phosphate Handling: Proximal Tubule

Apical

Basolateral

Block GA et al. Am J Kidney Dis 1998 Apr;31(4):607-17

Increased mortality associated with hyperphosphatemia

N = 6,407

7

Survival in Pre-Dialysis CKD According to Serum P Levels

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0 1 2 3 42745 1752 1053 350

Survival (y)Number of Persons at Risk

Prop

ortio

n Su

rviv

ing

P Level Relative to Estimated CrCl

Lowest QuintileAverage (Middle) QuintileHighest Quintile

CrCl = creatinine clearance.Kestenbaum et al. J Am Soc Nephrol 2005;16: 520-528.

8Dhingra, R. et al. Arch Intern Med 2007.

Risk of Incident CVD According to Baseline Phosphate Level in Framingham

DISORDERED PHOSPHATE HOMEOSTASIS: RISK FACTOR FOR ADVERSE CVD OUTCOMES

9

Rare Disorders of Phosphate Homeostasis

10

HypophosphatemiaUrinary phosphate wasting

Inappropriately low calcitriolRickets (osteomalacia)Variable (normal) PTH

X-linked hypophosphatemia

Autosomal dominant hypophosphatemia

Autosomal recessive hypophosphatemia

Tumor-inducedosteomalacia

FGF23 as Phosphatonin

11AJP-Endocrinol Metab • VOL 285 • JULY 2003

XTIOFD

ADHR

X XLH

Secreted by osteocytes/osteoblasts

12

FGF-23 in normal physiology

29 healthy men subjected to low phosphate diet with phosphate binder, followed by phosphate loading FGF-23 decreased with low

phosphate and increased with phosphate load FGF-23 may play an

important role in normal phosphate regulation

Ferrari, J Clin Endocrinol Metab 2004

Classic Physiological Actions of FGF23

FGF23

Phosphaturia 1,25D

PTH

Collateral damageCKD progressionLeft ventricular hypertrophyEndothelial dysfunctionVascular stiffnessDeath

? ?

+__

_

+

+

+

+

Wolf M. J Am Soc Nephrol 2010

FGF23:Stimulates phosphaturiaStimulates CYP24Inhibits CYP27B1Inhibits PTH

MEANWHILE….

14

15

Survival of Patients on Hemodialysis According to Type of IV Vitamin D Therapy

Teng et al. N Engl J Med. 2003;349:446-456.

Paricalcitol

Calcitriol

Sur

viva

l (%

)

0102030405060708090

100

0 5 10 15 20 25 30 35 40

Sur

viva

l (%

)

Switchto Calcitriol

0102030405060708090

100

0 5 10 15 20 25 30 35 40

Switch to Paricalcitol

3-year survival:59% vs 51%Log rank P<0.001

2-year survival:73% vs 64%Log rank P = 0.04

N = 67,399 N = 16,483

Follow-Up (mo)

16

Calcitriol Deficiency and SHPT as CKD Progresses

*Abnormal PTH based on Kidney Disease Outcomes Quality Initiative (K/DOQI) Clinical Practice Guidelines for Bone Metabolism and Disease in CKD. 2003.Kates et al. Am J Kidney Dis. 1997;30:809-813; Martinez et al. Am J Kidney Dis. 1997;29:496-502; Martinez et al. Nephrol Dial Transplant. 1996;11(suppl 3):22-28; St. John et al. Nephron. 1992;61:422-427.

GFR (mL/min/1.73 m2)

50

40

30

20

10

0105 95 7585 65 45 35 1555 25

1,25D

Lower range of 1,25D

102030405060708090

100

Pat

ient

s W

ith E

leva

ted

PTH

(%)*

CKD Stage 2 Stage 3

Cal

citri

ol1,

25(O

H) 2

D3

(pg/

mL)

Stage 4●

●

●

●

●

●●

●●

●

●

Serum phosphate is normal in CKD

Estimated glomerular filtration rate (mL/min) Estimated glomerular filtration rate (mL/min)

Gutiérrez OM et al. J Am Soc Nephrol. 2005

18

FGF-23 According to CKD Stage

Mean: 86.2Mean: 436

Gutierrez, et al JASN 2005

Disordered Mineral Metabolism in Rats with Anti-GBM Nephritis

Hasegawa et al. Kidney Int 2010

Effects of Anti-FGF23 Antibodies

Normalize 1,25D

Reverse CYP regulation

Decrease phosphaturia

Increase serum P

Hasegawa et al. Kidney Int 2010

Temporal aspects of disordered mineral metabolism in CKD

Anal

yte

conc

entr

atio

n

>10,000

1000

9060

3040>90 75 60 45 30 15 0 3 6 >12

GFR (mL/min/1.73 m2)

Time post-transplant (months)

1,25D(pg/mL)

cFGF-23(RU/mL)

1 2 3

4

Dialysis

Wolf M. J Am Soc Nephrol 2010

PTH(pg/mL)

Normal PTH range

P(mg/dL)

Normal P range

1. Increased FGF-23 is the earliest alteration in mineral

metabolism in CKD

2. Gradually increasing FGF-23 levels cause early

decline in 1,25D levels 3 .This frees PTH from

feedback inhibition, leading to SHPT

4. All these changes occur long before increases in

serum P levels are evident

FGF23 and Mortality in Incident ESRD

22Gutierrez et al N Engl J Med 2008

23

FGF23 and Mortality in Prevalent ESRD

Quartile 1= <1100 RU/mLQuartile 2= 1100–2700 RU/mLQuartile 3= 2701–8400 RU/mLQuartile 4= >8400 RU/mL

Jean et al. Nephrol Dial Transplant 2009; e-pub ahead of print

100

95

90

85

80

75

70

65

60

Sur

viva

l pro

babi

lity

(%)

Nb at risk 219 186 162 137Quartile 1 54 48 45 41Quartile 2 55 48 43 39Quartile 3 55 46 39 32Quartile 4 55 44 35 25

0 200 400 600 800Time (days)

Quartile 1

Quartile 2

Quartile 3

Quartile 4

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Model 1 Model 2 Model 3

Quartile 1 Quartile 2 Quartile 3 Quartile 4

HOST: Higher FGF23 Associated With Greater Risk of All-Cause Mortality in CKD 4

Model 1: age, race, gender.Model 2: Model 1 + smoking status, alcohol intake, DM, HTN, CVD, BMI, SBP, GFR, treatment assignment, homocysteine, hemoglobin, folate, B12, albumin, calcium, 25(OH)D, 1,25(OH)2D, iPTH, phosphorus, HDL, LDL, triglycerides, and total cholesterol.Model 3: Model 2 + use of medications.Kendrick JR, et al. J Am Soc Nephrol. 2011

Haz

ard

Rat

io fo

r Dea

th

≤216 RU/mL 217-380 RU/mL 381-945 RU/mL > 946 RU/mL

R RR

Prevalent Transplant Recipients: FGF23 & Composite Risk of Death or Allograft Loss

Wolf et al. J Am Soc Nephrol. 2011

0

10

20

30

40

Cum

ulat

ive

Inci

denc

e, C

ompo

site

Out

com

e (%

)

0 1 2 3Analysis time (years)

FGF23 Tertile 2FGF23 Tertile 3

FGF23 Tertile 1

Chronic Renal Insufficiency Cohort Longitudinal prospective cohort study of CKD eGFR 20 – 70 at entry N = 3,939 Oversampled black and Hispanic participants Detailed clinical data Medications Dietary data Blood and 24-hour urine samples Cardiovascular measures Longitudinal follow up

Feldman HI, et al. JASN 2003

http://porter.cceb.upenn.edu:7778/servlet/page?_pageid=55&_dad=portal30&_schema=PORTAL30�

FGF23 and Mortality:266 events, 20.3/1000 person-years

DeathP for trend < 0.001

Years of follow up

0 1 2 3 4 5

30

0

10

20

FGF23 Quartile 1

FGF23 Quartile 2

FGF23 Quartile 3

FGF23 Quartile 4

Isakova et al. JAMA 2011.

28

Stratified Analyses of FGF23 & Mortality

(MV-adjusted)

Isakova et al. JAMA 2011.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Model 1 Model 2 Model 3


Haz

ard

Rat

io fo

r CVE

FGF-23 and CVD Events Among Patients With Advanced CKD

Model 1: age, race, gender.Model 2: Model 1 + smoking status, alcohol intake, DM, HTN, CVD, BMI, SBP, GFR, treatment assignment, homocysteine, hemoglobin, folate, B12, albumin, calcium, 25(OH)D, 1,25(OH)2D, iPTH, phosphorus, HDL, LDL, triglycerides, and total cholesterol.Model 3: Model 2 + use of medications.Kendrick JR, et al. J Am Soc Nephrol. 2011

Parker et al. Ann Intern Med 2010

FGF23, CVD Mortality: Non-CKD

31

FGF23 and Left Ventricular Hypertrophy

Increase in mean LVMI (95% CI) per 1-SD increase

in Log FGF-23, %

p OR (95% CI) of LVH pr 1-SD increase in Log FGF-23

p

Unadjusted model

12 (4-18) <0.001 2.0 (1.2-3.4) 0.006

Multivariable-adjusted model*

11 (3-18) 0.01 2.3 (1.2-4.2) 0.01

Plus active vitamin D use

11 (4-18) 0.005 2.2 (1.2-4.3) 0.01

Plus phosphorus binder use

11 (4-18) 0.003 2.2 (1.2-4.2) 0.01

*Adjusted for age, gender, race, BMI, eGFR, diabetes, hypertension, and serum phosphate

LVH=left ventricular hypertrophy; LVMI=left ventricular mass index

Gutierrez et al. Circulation 2009; e-pub ahead of print

Ascending Quartiles of FGF23 are Associated with Rising LVMI

32

Left

vent

ricul

ar m

ass

inde

x, g

/m2.

7 P for linear trend <0.001

40

50

60


Fibroblast Growth Factor 23 Quartiles

45

55

Faul, Amaral, Oskuei et al. J Clin Invest. 2011.

LV Geometry According to Ascending Quartiles of FGF23

33

27 24 16 10

3531

3019

1112

16

21

27 33 3850

0102030405060708090

100


Prev

alen

ce,%

NormalRemodeling

Eccentric LVHConcentric LVH

Fibroblast Growth Factor 23 QuartilesFaul, Amaral, Oskuei et al. J Clin Invest. 2011.

FGF23 and Incident LVH

n Incident LVHN (%)

RR per unit increase in

lnFGF23All patients 411 84 (20%) 2.4No hypertension 138 13 (13%) 4.4

•Patients with normal LV geometry at baseline•Follow-up ECHO ~3 years later

34Faul, Amaral, Oskuei et al. J Clin Invest. 2011.

FGF23-Induced Hypertrophy of NRVM:FGFR-dependent but klotho independent

35

klotho

GAPDH

GAPDH

FGFR1

FGFR4

FGFR2

FGFR3

L CM BlH

Br K CM BlH

10010 25

FGF2

FGF23

Controlng/mL


Intramyocardial Injection of FGF23 LVH

36

Untreated7D 7D14D 14D

Vehicle FGF23

6.5

7

7.5

8

8.5

Untreated Vehicle FGF23

*

Untreated Vehicle FGF23

*

***

050

100150200250300350400450


Intravenous Injection of FGF23 LVH


MC

WGA

Vehicle FGF23

LV

wal

l thi

ckne

ss, m

m

0

0.5

1.0

1.5

2.0

2.5 * *

Free Wall Septum

0

100

200

300 *

Myo

cyte

cro

ss-

sect

iona

l are

a,μm

2

0

200

400

600

800

1000

FGF2

3, R

U/m

l

Blocking FGF23 Prevents LVH in 5/6 NPX


Sham 5/6 nephrectomy 5/6 nephrectomy+PD173074

0

0.1

0.2

0.3

0.4

0.5

0.6

Sha

m 5/6

5/6

+ P

D

Creatinine

0

50

100

150

200

250

Sha

m 5/6

5/6

+ P

D

SBP

WHERE DOES IT ALL BEGIN?

39

Phosphate, Race & Income in CRIC

Black: 1095White: 1196

Estimated P Intake:No difference by income

Gutierrez et al. J Am Soc Nephrol 2010

FGF23 and Income in CRIC

41

No difference in phosphate intake by

income

Sources of dietary phosphate differ in their “bioavailability”

MeatPlantAdditive

42

No difference in phosphate intake by

income

The Team Laboratory Investigators

– Christian Faul– Ansel Amaral– Behzad Oskuei

Clinical Investigators– Tamara Isakova– Julia Scialla– Orlando Gutierrez

Study Coordinators– Allison Barchi-Chung – Jessica Houston– Eva Schiaventao– Gabriela Vargas– Patricia Wahl

Students– Kelsey Smith

Collaborators– Harold Feldman– Josh Hare– Makoto Kuro-o– Orson Moe– Ming-Chang Hu– Marcus Brand– Harald Jueppner– Mary Leonard– Tony Portale– Isidro Salusky– Ravi Thadhani

CRIC investigators and coordinators Funding

– National Institutes of Health– University of Miami

Study participants

Questions

the rise of fgf23 from mendelian obscurity to mainstream...

Documents