Emerging risk factors and markers of CKD progression

Emerging risk factors and markers of CKD progression Florian Kronenberg Innsbruck Medical University, Division of Genetic Epidemiology

CKD: Relevance of the problem

Initiation and progression of CKD Traditional progression factors or markers: Initiating factors: Age Gender Ethnicity Family history of CKD Diabetes mellitus Metabolic syndrome Hyperfiltration states High normal urinary albumin excretion Dyslipidemia Nephrotoxins Primary kidney disease Urological disorders Cardiovascular disease Chronic Kidney Disease Emerging progression factors or markers:? Progression GFR decline ESRD Nature Rev. Nephrol. 5:677-89, 2009

Definition of CKD progression Surrogates of GFR slope Doubling of baseline serum creatinine level Need of renal replacement therapy (dialysis and/or transplantation) Particular relative increase from baseline serum creatinine level Yearly or monthly decline in GFR GFR reduction to 50% of baseline Graft loss Indices of renal damage Worsening of proteinuria Appearance of albuminuria in patients with diabetes

Mild to Moderate Kidney Disease Study 227 patients with primary non-diabetic CKD Patients with nephrotic syndrome excluded Recruited 1996/97 Age 46 ± 13 years Iohexol clearance at baseline: average GFR 64 ± 39 ml/min Followed for 7 years Endpoint: doubling of serum creatinine and/or ESRD 177 completed follow-up 65 reached endpoint (36 Crea-doubling, 29 ESRD)

ADMA: Asymetric Dimethylarginine Potent and long-lasting endogenous inhibitor of NO synthase less NO production NO is a potent vasodilatator and regulator of the vascular tone and blood flow Kidney is the main site of ADMA removal ADMA markedly increased in renal patients High ADMA levels related to atherosclerotic complications

ADMA: Biochemical Pathway 20% Renal excretion Proteins with ADMA residues ADMA L-arginine NO synthase LDL cholesterol Homocysteine Hyperglycemia Hypertension Smoking Inflammation Aging D D A H 80% Dimethlyamine + Citrulline DDAH, dimethylarginine dimethylaminehydrolase NO Consequences of decreased NO Decreased renal plasma flow Increased renovascular resistance Increased blood pressure Endothelial damage Progression of chronic kidney disease Nature Rev. Nephrol. 5:677-89, 2009

ADMA and progression of CKD: MMKD-Study Cox regression: HR 1.47 (95% CI 1.12-1.93) for 0.1 µm/l increase Fliser et al.: J.Am.Soc.Nephrol. 16:2456-61, 2005

ADMA and progression of CKD and death n=29 n=31 ADMA <0.76 µm/l ADMA <0.76 µm/l ADMA 0.76 µm/l ADMA 0.76 µm/l n=131, age 71±11yrs, GFR 8-77 ml/min, follow-up 27 mos Ravani et al.: J.Am.Soc.Nephrol. 16: 2449-55, 2005

ADMA and progression of CKD Hanai et al: NDT 24:1884-8, 2009: Progression of diabetic nephropathy 37 of 225 patients with T2DM Lajer et al: Diabetes care 31:747-52, 2008: 397 patients with T1DM and nephropathy Yearly decline in GFR p<0.001

Calcium-phosphate metabolism Progression of CKD in animal models: High phosphate High PTH Lack of active vitamin D Ca-Ph metabolism and progression of CKD in humans: High phosphate (5 of 5 studies) and high Ca*Ph (3 of 4 studies) High PTH levels (2 of 2 studies) Fibroblast Growth Factor 23 (FGF23): Recently identified phosphatonin Regulator of phosphate balance Under physiological conditions: high phosphate load results in increased FGF23 secretion and phosphaturia

Calcium-phosphate metabolism and progression Results from the MMKD Study Non-progressors (n=112) Progressors (n=65) p-value FGF 23 c-terminal (ru/ml) 92 ± 113 351 ± 394 <0.001 FGF 23 intact (pg/ml) 35 ± 28 69 ± 70 <0.001 Phosphate (mmol/l) 1.04 ± 0.38 1.25 ± 0.27 <0.001 Ca x P product (mmol 2 /L 2 ) 2.46 ± 0.85 2.90 ± 0.65 <0.001 Parathormone (pmol/l) 6.5 ± 5.3 22.5 ± 20.0 <0.001 Fliser, Kollerits et al.: J.Am.Soc.Nephrol. 18:2600-8, 2007

Multiple Cox regression analysis Adjusted for age, sex, GFR, proteinuria and the other variables of this table Variable (increment) HR (95% CI) p Phosphate (0.1 mmol/l) 1.052 (0.952-1.162) 0.322 Ca x P product (0.1 mmol 2 /L 2 ) 1.024 (0.981-1.068) 0.279 Parathormone (1 pmol/l) 1.009 (0.993-1.025) 0.273 FGF23 c-terminal (10 ru/ml) 1.014 (1.005-1.024) 0.002 FGF23 intact (10 pg/ml) 1.061 (1.018-1.106) 0.005 Fliser, Kollerits et al.: J.Am.Soc.Nephrol. 18:2600-8, 2007

Multiple Cox regression analysis Adjusted for age, sex, GFR, proteinuria and the other variables of this table Variable (increment) HR (95% CI) p Phosphate (0.1 mmol/l) 1.052 (0.952-1.162) 0.322 Ca x P product (0.1 mmol 2 /L 2 ) 1.024 (0.981-1.068) 0.279 Parathormone (1 pmol/l) 1.009 (0.993-1.025) 0.273 FGF23 c-terminal (10 ru/ml) 1.014 (1.005-1.024) 0.002 FGF23 intact (10 pg/ml) 1.061 (1.018-1.106) 0.005 FGF23 c-terminal +250 ru/ml 35% increased risk (adjusted for age, sex, GFR and proteinuria) Fliser, Kollerits et al.: J.Am.Soc.Nephrol. 18:2600-8, 2007

FGF23 and progression of CKD in MMKD Progression 10% 60% Fliser, Kollerits et al.: J.Am.Soc.Nephrol. 18:2600-8, 2007

Vitamin D and CKD progression 168 newly referred patients with CKD stages 2-5 Follow-up median 57 mos. Endpoint: dialysis treatment in 48 cases 10 ng/ml increase in 25- hydroxy vitamin D level was associated with a 40% decrease in hazard ratio for CKD progression Ravani et al.: Kidney Int. 75:88-95, 2009

Adiponectin Produced in adipocytes Central role in glucose and lipid metabolism (insulin sensitizer) An anti-inflammatory, anti-atherosclerotic and vasculo-protective cytokine A large number of studies showed an association between low adiponectin levels and negative outcomes Adiponectin is elevated in patients with kidney impairment

High adiponectin and CKD progression Study Study population End points Specific observation Followup MMKD Study 2007 177 nondiabetic patients with primary CKD Doubling of serum creatinine and / or ESRD (n=65) Observed only in men Median 53 mos. EURAGEDIC Case-Control Study 2008 198 patients with T1DM with nephropathy Dialysis or kidney transplantation (n=40) Median 8.1 yrs. Finish Diabetic Nephropathy Study 2008 1330 patients with T1DM Progression to ESRD (83/296 patients with macroalbuminuria) No association in patients with normo- or microalbuminuria Mean 5 yrs. Kollerits et al.: Kidney Int. 71:1279-86, 2007 Jorsal et al.: Kidney Int. 74:649-54, 2008 Saraheimo et al.: Diabetes care 31:1165-9, 2008

Adiponectin association "reshaped" High adiponectin in other studies predicted lower risk for cardiovascular events in ESRD (Zoccali et al. 2002) mortality in CKD 3 and 4 in the MDRD Study (Menon et al. 2006) mortality in patients with CHF (Kistorp et al. 2005) all-cause and CVD mortality in CAD patients (Pilz et al. 2006) and several other studies The association of adiponectin might turn in the opposite direction in the presence of severe disease conditions A compensatory attempt to attenutae endothelial and vascular damage? Adiponectin resistance?

Apolipoprotein A-IV and CKD progression Activates LPL and LCAT MMKD Study Median = 26 mg/dl Stimulates cholesterol efflux from peripheral cells Reverse cholesterol transport Antioxidative properties Strong association with kidney function p<0.0001 Boes et al.: J.Am.Soc.Nephrol. 17:528-36, 2006

Natriuretic peptides and CKD progression: MMKD Potent hypotensive, diuretic and natriuretic peptides involved in maintaining cardiovascular and renal homeostasis Produced in the kidney Increased concentrations associated with CVD and renal disease Renoprotective properties compensatory increase in CKD Variable (1 SD increment) HR (95% CI) p-value NT-pro BNP (527 ng/l) 1.15 (0.96-1.38) 0.13 A-type natriuretic peptide (131 pmol/l) 2.11 (1.59-2.80) <0.001 Adrenomedullin (0.42 nmol/l) 2.60 (1.85-3.64) <0.001 Adjusted for age, sex, GFR, and proteinuria Dieplinger et al.: Kidney Int. 75:408-14, 2009

Calculating the gain in information GFR Proteinuria ADMA FGF23 ANP Adrenomedullin NT-proBNP ApoA-IV Problem of correlation of variables (multicollinearity)

MMKD Study: Comparison of parameters adjusted for age, sex, GFR and proteinuria Nature Rev. Nephrol. 5:677-89, 2009

Genomewide association studies (GWAS) 23 pairs of chromosomes Genotyping of up to 1 million single nucleotide polymorphisms (SNPs) in thousands of persons Phenotype (e.g. CKD, CKD progression, GFR) Association analysis

Genetic factors for CKD progression Advantages of polymorphisms: Stability: inherited at conception and do not change with disease Causality is likely (no reverse causation) Gene ADIPOQ (adiponectin) Strong association explains 8% Intermediate phenotype Plasma adiponectin concentrations Strong association explains 10% Endphenotype Progressive CKD Nature Rev. Nephrol. 5:677-89, 2009

Genetic factors for CKD progression Advantages of polymorphisms: Stability: inherited at conception and do not change with disease Causality is likely (no reverse causation) Mendelian Randomization Gene ADIPOQ (adiponectin) Strong association explains 8% Intermediate phenotype Plasma adiponectin concentrations Strong association explains 10% Endphenotype Progressive CKD Weak association explains 0.8% (0.08 x 0.10) Nature Rev. Nephrol. 5:677-89, 2009

Genetic factors for CKD progression Advantages of polymorphisms: Stability: inherited at conception and do not change with disease Causality is likely (no reverse causation) Mendelian Randomization Gene ADIPOQ (adiponectin) Strong association explains 8% Intermediate phenotype Plasma adiponectin concentrations Strong association explains 10% Endphenotype Progressive CKD Requires large sample sizes Weak association explains 0.8% (0.08 x 0.10) Nature Rev. Nephrol. 5:677-89, 2009

Genetic factors for CKD progression Advantages of polymorphisms: Stability: inherited at conception and do not change with disease Causality is likely (no reverse causation) Mendelian Randomization No reverse causation Gene ADIPOQ (adiponectin) Strong association explains 8% Intermediate phenotype Plasma adiponectin concentrations Strong association explains 10% Endphenotype Progressive CKD Requires large sample sizes Weak association explains 0.8% (0.08 x 0.10) Nature Rev. Nephrol. 5:677-89, 2009

GWAS on kidney function Meta-analysis: CKDGen consortium 20 population-based cohort studies >90,000 persons 20 new genetic loci for renal function and chronic kidney disease Uromodulin (UMOD): codes for Tamm-Horsefall protein Association with prevalent and incident CKD and egfr creatinine Rare mutations cause monogenic forms of kidney diseases Köttgen et al.: Nat.Genet. (online)

Future developments Combination of GWAS and metabolomics: Gieger et al.: PLoS Genetics 2008 Illig et al.: Nature Genetics 2010 Personalized health-care system Nature Rev. Nephrol. 5:677-89, 2009

Summary Chronic Kidney Disease Progression GFR decline ESRD Emerging progression factors or markers: (number of studies) They are independent from GFR and proteinuria. Many of them are independent from each other. Some of them might also reflect a cardiorenal syndrome. Large studies are urgently required.

The MMKD Study Group Barbara Kollerits Eva Boes Paul König Karl Lhotta Ulrich Neyer Danilo Fliser Jan Kielstein Iris M. Heid Benjamin Dieplinger Peter Riegler Eberhard Ritz Gerhard Müller Günter Kraatz Johannes Mann Werner Riegel Vedat Schwenger Katharina-Susanne Spanaus Arnold von Eckardstein Renal Units: Project Support: Innsbruck, Feldkirch, Greifswald, Heidelberg, München-Schwabing, Göttingen, Homburg/Saar, Bozen GEN-AU (Austrian Genome Project) Austrian Science Fund, Austrian National Bank Austrian Academy of Sciences Austrian Heart Fund Else Kröner-Fresenius Stiftung