The gut microenvironment in CKDa promising target of therapy

P. Evenepoel

Department of Internal Medicine, NephrologyUniversity Hospitals Leuven

Department of Immunology and Microbiology, laboratory of Nephrology, KU Leuven

Antalya 2018

Disclosures

• Advisory Board: Kaleido, Hepawash

• Gut microenvironment in CKD• Consequences of a disturbed gut

microenvoronment in CKD • Targeting the gut microenvironment

Outline

Gut microenvironment/ecosystem in health

Gut microbiota Gut epithelial barrier

Affects host systemic immune function

Affects host metabolism (energy, fat, glucose, bone..)

Protects against entry of microorganisms, microbial toxins, digestive enzymes, antigens… and other harmful luminal contents

• Epithelial cell• Apical junctional complex

• Tight junctions• Transmembrane: occludin, claudin• Cytosolic: zonula occludens• Perijunctional: actin-myosin

• Adherens junction

SYMBIOSIS-COMMENSALISM (alliance)

Gut ecosystem in CKD

Gut microbiota Gut epithelial barrier

DYSBIOSIS

• Leaky gut• Altered microbial composition• Altered microbial metabolism

X X

The gut ecosystem in CKD

Gut microbiota Gut epithelial barrier

DYSBIOSIS

• Leaky gut• Altered microbial composition• Altered microbial metabolism

X X

Vaziri et al. Kidney Int 2013;83(2):308-15

• ESRD• Drug therapy• Diet• Exposure to dialysis

• ESRD

CKD and gut microbiota

Humans Rats

CKD and gut microbiota

Wong et al. AJN 2014

CKD induces expansion of urease and uricase-containing, indole and p-cresol-forming and contraction of short-chain fatty acid-producing microbiota

Poesen et al. ASN 2013 (unpublished data)

CKD and microbial metabolism

Poesen et al. JASN 2015

Volatile organic compounds patterns

Evenepoel et al. Kidney Int 2009; Nicholson et al. Science 2012; Scott et al. Pharmacol Res 2013; David et al. Nature. 2014

CKD and microbial metabolism

Protein FermentationCHO fermentation

CKD and microbial metabolism

• Colonic -NH3 availability• Dietary protein intake• Small intestinal digestion and absorption

efficacy• Colonic CHO availability

• ≈dietary fiber intake• Colonic transit time

Evenepoel doctoral thesis, 1997Evenepoel Kidney int 2009Bammens et al. Kidney Int 2003David et al. Nature. 2014

CKD

≈

CKD, a state of increased protein fermentation

CKD 1-2 CKD 3 CKD 4-5

The gut ecosystem in CKD

Gut microbiota Gut epithelial barrier

DYSBIOSIS

• Leaky gut• Altered microbial composition• Altered microbial metabolism

X X

Vaziri et al. Nephrol Dial Transpl 2012:27; 2686-93

CKD and Intestinal epithelial barrier

Vaziri et al. NDT 2012

Western blotting

Intestinal permeability

D-lactate: increased serum levels in CKD

PEG: increased relative 24h urinary recovery after intestinal exposure

Magnusson et al. Gut 1991

Shi et al. Dig Dis Sci 2014

uremia

Causes of leaky gut in CKD

Diet

GIT physiology (TT, pH…)

polypharmacy

comorbidity

URMs(urea, phenols, …)

hypervolemia

Hemodynamic instability-ischemia

Direct toxicity: NH4OH Indirect toxicity through ATP depletion: phenols, indoles

Leaky gutGut dysbiosis

Consequences of gut dysbiosis in CKD

Diet

GIT physiology

polypharmacy

comorbidity

Uremic toxins(urea, phenols)

hypervolemia

ischaemia

Altered microbiota

Altered metabolism

Phenols/indoles↑ Lipopolysaccharides↑

Leaky gutGut dysbiosis

Chronic Kidney Disease Dialysis

CHO fermentation

protein fermentation

SCFAs↓

Gut ecosystem in CKD

Prevotella Bacteroidetes

Feed-forward cycle

• Gut microenvironment in CKD• Consequences of a disturbed gut

microenvoronment in CKD • Targeting the gut microenvironment

Outline

SCFAs↓ Phenolindole↑

LPS↑

Consequences of disturbed gut ecosystem in CKD

Consequences of gut dysbiosis in CKD

Diet

GIT physiology

polypharmacy

comorbidity

Uremic toxins(urea, phenols)

hypervolemia

ischaemia

Altered microbiota

Altered metabolism

Phenols/indoles↑ Lipopolysaccharides↑

Leaky gutGut dysbiosis

Chronic Kidney Disease Dialysis

CHO fermentation

protein fermentation

SCFAs↓

Prevotella Bacteroidetes

Consequences of disturbed gut ecosystem in CKD

Enteroendocrine L cell

SCFAs: mechanisms of action

Adapted from Li et al. Drug Design, Develop &Ther 2017; Koh et al. Cell 2016; Schroeder et al. Cell Host & Microbe 2018

Fuel colonocytes

Activation of G-Protein Coupled Receptors

Stimulation of the release of (anorexigenic)hormones

PYY GLP-1

Inhibition of histone deacetylase

Enteroendocrine L cell

SCFA, downstream effects

Appetite, glucose & lipid metabolism

Inflammation ↓Blood pressure↓(cardiovascular homeostasis)

Li et al. Drug Design, Develop &Ther 2017; Marques et al. Circulation 2017; Koh et al. Cell 2016

CKD

Colonic homeostasis

Consequences of gut dysbiosis in CKD

Diet

GIT physiology

polypharmacy

comorbidity

Uremic toxins(urea, phenols)

hypervolemia

ischaemia

Altered microbiota

Altered metabolism

Phenols/indoles↑ Lipopolysaccharides↑

Leaky gutGut dysbiosis

Chronic Kidney Disease Dialysis

CHO fermentation

protein fermentation

SCFAs↓

Prevotella Bacteroidetes

Consequences of disturbed gut ecosystem in CKD

Meijers B K , Evenepoel P Nephrol. Dial. Transplant. 2011;26:759-761

Metabolism indoles & phenols

Gut Bacteria

p-cresol

Trp

Phe

Protein

Peptide

Indole

Free p-cresyl sulphate

Free indoxyl sulphate

PCS/IndS in CKD

Anal

yte

(tota

l) co

ncne

ntra

tion

CKD1-2 CKD3 CKD4-5 CKD5D Tx CKD3T

Barreto et al. CJASN 2009

Circulating levels↑ elimination↓

Nephron loss Downregulation of transporters

production↑ Free fraction↑ Glucuronidation/Sulphation↑

Circulating levels↓ elimination↑ production↓

Immunosuppression Antbiotics

X 10-30

Indoxyl sulphate

p-cresyl sulphate, measured as p-cresol

Barreto et al. CJASN 2009; Meijers et al. CJASN 2010; Dobre et al. CJASN 2013; Poesen et al. NDT 2016; Poesen et al. CJASN 2016; Liabeuf et al. Circ J 2016; Sirich et al. Kidney Int 2013

Meijers et al. CJASN 2010

[PCS] & [IndS]: determinants

•Age•Gender•eGFR*/RRF•Diet•Diabetes•Colonic transit time

Itoh et al. Anal Bioanal Chem. 2012; Melamed et al BMC Nephrol 2013; Meijers et al. CJASN 2012; Lin et al. Kidney Blood Press Res. 2015; Viaene et al. PlosOne 2014

Lack of relationship Regional differencesDeterminants

* Except renal transplant recipients

QATs 1 and 3

Oxidative stress

Increased ROS productionIncreased NADPH oxidase activity

AhR

RAASactivation

Cellular senescence

pro-inflammatory &pro-fibrotic genes↑(e.g. IL-1β, IL-6, TNF-α, TGF- β, PAI-1)

Osteoblast-specific

proteins↑

Klotho↓

Vascular calcification

Renal fibrosisCardiac fibrosisatherosclerosis

Renal, Cardiovascular, and Bone dysfunction, Anemia

NF-KB

MAPKs

senescence-related proteins↑

Glomerulirpodocyte

injury

OAT

PTHR1↓Obl dysfunction

Low bone turnover

Vascular calcification

Fetuin-↓

TGF-↑HIF↓

Renal tissue remodeling &fibrosis

Anemia

Stabi-lization

TF

Throm-bosis

EGFRactivation

EMT

Signaling pathways

Meijers, Jouret, Evenepoel Pharm Res 2018

Free PCS ≥1.97 mg/l

Free PCS <1.97 mg/l

p-cresyl Sulphate, measured as p-cresol

Mortality, dialysis

Bammens et al. Kidney Int 2006 Mar;69(6):1081-7

HD, prevalent, n=175Follow-up: 34 monthsEndpoint: n=60

p-cresyl sulphate

PCS IndS RefMortality √ √ Bammens et al. Kidney Int 2006; Barreto et

al. CJASN 2009; Liabeuf et al. NDT 2010Wu et al. NDT 2012; Lin et al. PlosOne 2015 (meta-analysis)

CV morbidity Vascular calcification √ Barreto et al. CJASN 2009; Liabeuf et al. NDT 2010

Atherosclerosis √ √ Jing et al. Kidney Int 2015; Hsu et al. Clin Invest Med 2013

Thrombosis √ Wu et al. JASN 2015Art stiffness √ √ Barreto et al. CJASN 2009Prolonged QTc √ Tang et al. PlosOne 2015MACE √ Meijers et al. Kidney Int 2008

Renal disease progression

√ Wu et al. NDT 2011

*Associations stronger or only observed for free levels

Toxicity: clinical evidence*

Consequences of gut dysbiosis in CKD

Diet

GIT physiology

polypharmacy

comorbidity

Uremic toxins(urea, phenols)

hypervolemia

ischaemia

Altered microbiota

Altered metabolism

Phenols/indoles↑ Lipopolysaccharides↑

Leaky gutGut dysbiosis

Chronic Kidney Disease Dialysis

CHO fermentation

protein fermentation

SCFAs↓

Prevotella Bacteroidetes

Consequences disturbed gut ecosytem in CKD

LPS and oxidative stress/inflammation

CKD, a state of increased oxidative stress and micro-inflammation

LPS

mCD14 sCD14

clearance

monocyte

Author n  CRP threshold (mg/L) prevalence (%)McIntyre et al. 98 10 53CREED Investigators 112 5 65Owen and Lowrie 1054 8 35Qureshi et al. 128 10 53Zimmermann et al.  280 8 46Yean et al.  91 5,2 51

Stenvinkel Blood Purif 2001;19:53-61Carrero and Stenvinkel Sem Dialysis 2010;23:498-509

Median CRP level in general Western population : 1-3 mg/lMedian CRP level in European dialysis patients: 4-5 mg/l

CKD stage 5D

CKD is a state of micro-inflammation

CVD CKD

InfectionsWasting

Insulin resistance

INFLAMMATION&

OXIDATIVE STRESS

Consequences of inflammation and oxidative stress

Poesen et al. CJASN 2015

Patient and Renal survival

Leuven mild-to-moderate CKD cohort (n=495)

sCD14

• sCD14 levels are a marker of endotoxin exposure (endotoxinemia)• sCD14 levels associate negatively with eGFR• SCD14 levels associate positively with surrogate markers of inflammation

Karolinska HD cohort, prevalent (n=211)

Raj et al. AJKD 2009

PATIENT SURVIVAL RENAL SURVIVAL

All-cause mortality

Consequences of gut dysbiosis in CKD

Diet

GIT physiology

polypharmacy

comorbidity

Uremic toxins(urea, phenols)

hypervolemia

ischaemia

Altered microbiota

Altered metabolism

Phenols/indoles↑ Lipopolysaccharides

INFLAMMATION, OXIDATIVE STRESSCVD-PEW-CKD-Hypertension

INSULIN RESISTANCEINFECTIONS

Leaky gutGut dysbiosis

Chronic Kidney Disease Dialysis

CHO fermentation

protein fermentation

SCFAs↓

Prevotella Bacteroidetes

Consequences disturbed gut ecosytem in CKD

Sumida et al. JASN 2017

Height↑

Colon length↑

Colon Transit time↑

Minko et al. FASEN J 2014 (abstract)

Shapiro et al. CJASN 2015

What tells epidemiology?

Some remarkable associations

CONSTIPATION BODY HEIGHT

MORTALITYIncident CKD

• Gut microenvironment in CKD• Consequences of a disturbed gut

microenvoronment in CKD • Targeting the gut microenvironment

Outline

• Diet • Prebiotics, probiotics, synbiotics, antibiotics, fecal

microbiota transplant• Adsorbants• Drug therapy to alter nutrient availability• Drug therapy to decrease colonic transit time• Targeting microbial metabolism

Targeting the colonic microenvironment

Treatment options

Adapted from Poesen, Meijers, Evenepoel Sem Dial 2013Vitetta and Globe Mol Nutr Food Res 2013;Ramezani and Raj JASN 2014; Wang et al. Cell 2015; Devlin et al. Cell Host & Microbe 2016; Mishima et al. JASN 2014

Manipulating the Bacteroidestryptophanase gene

Diet and nutriceuticals

Protein restriction

Poesen et al. Plos1 2015

Healthy volunteers: n=29RCT, Interventions:

High protein: 125 g/dLow protein: 50 g/d

Dietary protein restriction“Usual” intake

Kopple et al. Kidney int 2000

Danger of Protein Restriction:

Protein Energy Malnutrition

Up to 75% in CKD stage 5D

Dietary fiber supplementation

n=13438 n=1105 n=30

Fruit and vegetable restriction

Fear for Hyperkalemia

Krishnamurthy et al. Kidney Int 2012 Kalantar-Zadeh et al. JRN 2002

What is the “usual” intake?

Dietary fiber

*prebiotic

Insoluble fiber

Soluble fiber

Dietary fiber supplements: a safe and valid alternative?

*a non-digestible food ingredients that beneficially affect the host by selectively stimulating growth, and/or activity, of one or a restricted number of bacteria in the colon

Fruit & Vegetables

Soluble highly fermentable

oligosaccharides

Soluble highly fermentable

fiber

Intermediate soluble

fermentable fiber

Insoluble slowly

fermentable fiber

Insoluble non-fermentable

fiber

Examples FOS, GOS, lactulose Resistant starch, pectin, guar gum, inulin

Psyllium, ispaghula, oats

Wheat bran, lignin, fruit and vegetables

Cellulose, stercula, methylcellulose

Site of action

Dietary Sources

• Legumes, nuts and seeds

• Wheat, rye• Onions, garlic,

artichoke

• Legumes/pulses

• Rye bread, barley

• Firm bananas• Buckwheat

groats, oats• Cooked and

colled pasta, patato, and rice

• Seeds of the plant Plantago Ovata, and oats

• Some vegetable and fruit

• Wheat bran, wholegrain cereal, Rye, brown rice, …

• High fiber grains and cereals

• Nuts, seeds• Skin of fruits

and vegetables

Not all Dietary fibers are created equal

Correlation between uremic toxins and dietary components of protein and fiber intake in 40 CKD patients

M. Rossi et al. Nutr, Met & CVD 2015

Dietary determinants of serum concentrations of PCS and IS

in healthy individuals and patients with CKD: a cross-

sectional observational study (n=250)

Evenepoel data on file

Protein/Fiber ratio

 

 

 

 

 

 

 

 

W0 W7W6W5W4 W3 W2 W1 W8

          

baseline  primary endpoint

run‐out Oligofructose ‐inulin 

Clinical studies

Meijers et al. NDT 2010

HD, 4-wk – open labed n=22•OF-inulin, escalating dose

HD, 6 wk - single blind RCT•Fiber: Resistant starch ≈ 18 g (n=28)•Control: Waxy corn starch (n=28)

Sirich et al. CJASN 2014

Adsorbant

• Ai Xi Te• Niaoduqing granules

Japan, Taiwan, Korea

AST-120 (kremezinTM): EPPIC trials

Evaluation Prevention of Progression in CKD trialsCKD (sCreat<5mg/dL): n=2035; RCT (placebo vs AST-120 3 g t.i.d.)

Schulman et al. JASN 2014 (ePUB)

Gut Microbiota in Health and Disease

Hippocrates, 400 BC

“First, do not harm”

• Proton pump inhibitors• Iron supplements• Phosphate binders• Antibiotics• Immunosuppressive agents

Drugs affecting the colonic microenvironment

PPI

Interstital nephritisProtein malbasorption

Renal failure

Phenols/indols↑

• Gut microbiota plays an important role in health and disease

• The colon is an appealing target of therapy in CKD and beyond.

Take home messages

Evenepoel Ped Nephol 2017

• Adsorbants so far failed to show a benefit on hard endpoints in RCT

• Dietary interventions are especially promising, but their efficacy remains to be proven.

• Altered co-metabolism may be in the causal way between a Western diet and diseases of civilization, including CVD and CKD

• Metagenomics will become an important clue to personalized – precision medicine.

Take home messages

What should we do?

“Let food be thy medicine”

Hippocrates

Keep it simple

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