the gut microenvironment in ckd a promising target of therapy · gut dysbiosis leaky gut...
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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 ASN 2013 (unpublished data)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
BadGood