Transcript Dyslipidemia & Diabetes

Hepatosteatosis
Prof Samir Helmy Assaad-Khalil
Unit of Diabetes & Metabolism
Alexandria Faculty of Medicine
2007
Agenda
 Definition
 Common Causes of Steatosis
 Prevalence Data
 Ethnic and gender differences
 Relationship between fatty liver disease & Met.
Syndrome
 Pathogenesis of fat accumulation in the liver
 Screening tests / Diagnosis
 Management
Definition
 Hepatosteatosis is defined as fat deposition in
the liver that exceeds 5% of the total weight of
liver, or with > 5% of hepatocytes containing fat
deposits under light microscopic examination
 It occurs under several disease states.
Fatty disorders of the liver may be
l
 Alcoholic (AFLD)
 Non-alcoholic.(NAFLD)
NAFLD includes both:
 Hepatic Steatosis
 NASH
l
l
l

Causes of Nonalcoholic Fatty Liver Disease
Nutritional
Drugs
Metabolic/Genetic
Obesity
Type 2 DM
Protein-calorie
malnutrition
Starvation
Total parenteral nutrition
Rapid weight loss
Corticosteroids
Estrogens
Salicylates
Calcium channel
blockers
Amiodarone
Tamoxifen
Tetracycline
Chloroquine
Perhexiline maleate
Wilson's disease
Lipodystrophy
Dysbetalipoproteinemia
Weber-Christian
disease
Wolman's disease
Cholesterol ester
storage
*HIV, human immunodeficiency virus.
Other
Environmental
hepatotoxins
Inflammatory bowel
disease
HIV* infection
Small bowel diverticulosis
Inborn Errors of Metabolism Associated
With Steatosis
 Abetalipoproteinemia
 Familial hepatosteatosis
 Galactosemia
 Glycogen storage disease
 Hereditary fructose intolerance
 Homocystinuria
 Systemic carnitine deficiency
 Tyrosinemia
 Resfum's disease
 Schwachman's syndrome
 Weber-Christian syndrome
 Wilson's disease
Acquired Metabolic Disorders Associated
With Steatosis

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



Diabetes mellitus
Obesity
Inflammatory bowel disease
Jejuno-ileal bypass
Kwashiorkor and marasmus
Serum lipid abnormalities
Starvation and cachexia
Severe anemia
Total parenteral nutrition
Drugs/Toxins Associated With Steatosis
Metals
Antibiotics
 Azaserine
 Antimony
 Bleomycin
 Barium salts
 Puromycin
 Borates
 Tetracycline
 Carbon disulfide
Other drugs
 Chromates
 Amiodarone
 Phosphorus
 Coumadin
 Rare earths of low atomic numbers
 Dichloroethylene
 Thallium compounds
 Ethionine
 Uranium compounds
 Ethyl bromide
 Estrogens
Cytotoxic/cytostatic drugs
 Flectol H
 l-Asparaginase
 Glucocorticoids
 Azacytidine
 Hydrazine
 Azauridine
 Hypoglycin
 Methotrexate
 Orotate
 Perhexilene maleate
 Safrole
Prevalence Data: Risk Factors
Obesity
60-95%
Distribution of NAFLD by Racial/Ethnic
Group
9%
29%
4%
10%
16%
17%
6%
6%
59%
44%
NAFLD Study Population
Caucasian
African-American
Estimated Alameda County
Population (represented by KP Membership)
Latino – Hispanic
Asian
Other
Distribution of Gender in Persons with
NAFLD
39
40
35
Male = 77
Female = 74
32
Number of 30
Patients 25
23 23
22
20
15
10
5
0
6
6
0
Caucasian
LatinoHispanic
AfricanAmerican
Asian
Disease Associations in Different Racial/
Ethnic Groups With NAFLD
Caucasian
LatinoHispanic
AfricanAmerican
Asian
P- value
34.0
34.0
37.8
26.7
P<0.001*
T2DM (%)
47.9
45.6
50.0
25
P=0.03*
Lipids (%)
49.2
43.4
57.1
57.1
NS
BMI, mean
(kg /
m2)
* Asian versus other groups combined
* Asian versus other groups combined
Clinical features of MS in patients with
NASH
Yasemin H. et al., Annals of Hepatology 2006; 5(2): April-June: 109-114
Chronic hyperinsulinemia &
carbohydrate ingestion
 Chronic hyperinsulinemia & carbohydrate
ingestion stimulate de novo lipogenesis by
stimulating the activity of lipogenic enzymes such
as the sterol regulatory element binding proteins
(SREBP-1c).
 The FFA stored in the liver can originate from
hydrolysis of dietary chylomicrons or adiposity.
SREBPs suppress IRS-2-mediated
insulin signalling in the liver
 Insulin receptor substrate 2 (IRS-2) is the main
mediator of insulin signaling in the liver,
controlling insulin sensitivity.
 Sterol regulatory element binding proteins
(SREBPs) directly repress transcription of IRS-2
and inhibit hepatic insulin signaling.
Ide T et al., Nat Cell Biol. 2004 Apr;6(4):351-7.
Pathogenesis
“2 Hit” Paradigm
“First hit”
–
“Second hit” –
Excess fat accumulation
Intrahepatic oxidative stress
Lipid peroxidation
TNF-alpha, cytokine cascade
Oxidative Stress & Mitochondrial
Changes
 Chronic oxidative stress has been implicated with
a) Formation of lipid hydroperoxides.
b) Induction of certain microsomal enzymes e.g. cytochrome
P450 2 El.
 Mitochondrial changes:
a) Mitochondrial damage with inhibition of mitochondrial
electron transport chain activity.
b) Release of mitochondrial free radicals.
c) Depletion of mitochondrial glutathione pools.
Kupffer`s Cell Dysfunction
 Hepatic steatosis also promotes:
a) Kupffer’s cell dysfunction
b) Impaired phagocytosis
c) Chronic low grade endotoxemia.
 Endotoxemia stimulate hepatic production of:
a) TNF- 
b) IL-6 and IL-8
c) Promote neutrophil chemotaxis & an inflammatory
response.
Adiponectin
 Decreased serum adiponectin concentrations
correlates with hepatic fat content in patients with
type 2 diabetes.
 Hepatocyte growth factor (HGF) is not only an
antiapoptotic and antifibrotic factor of liver, but it
is also an adipokine.
Serum leptin & NASH studies in humans
Leptin in the Field of Hepatic Fibrosis:
A Pivotal or an Incidental Player?
CVH, chronic viral hepatitis; NASH, nonalcoholic steatohepatitis;
NAFLD,nonalcoholic fatty liver disease
Sotirios K. et al Dig Dis Sci DOI 10.1007/s10620-006-9126-0
Serum Leptin Levels Are Associated With
Tamoxifen-Induced Hepatic Steatosis
Serum leptin levels in patients with a normal liver or stable hepatic
steatosis (group 1) and with increased hepatic steatosis (group 2)
Nazan Günel et al., Curr Med Res Opin 19(1):47-50, 2003.
Ghrelin in NAFLD
 Ghrelin is reduced in NAFLD vs. controls
 Insulin resistance is a major factor controlling
ghrelin levels in subjects with and without
NAFLD.
Tumor necrosis factor-α (TNF-α) gene
 Tumor necrosis factor-α (TNF-α) gene expression
is increased in adipose tissue in insulin resistant
obese and type 2 diabetic patients.
 In patients with NASH, TNF-α gene expression is
increased in both hepatocytes and adipose tissue.
The microbial theory
 Conversion of choline into methylamines by
microbiata in strain 129S6 on a high-fat diet
reduces the bioavailability of choline and mimics
the effect of choline-deficient diets, causing
NAFLD.
 Fatty liver due to chronic choline-deficient diet
exacerbates liver hepatitis, which is predominantly
facilitated by T cells.
 Delayed intestinal transit may contribute to
intestinal bacterial overgrowth (IBO).
Soza A et al., Dig Dis Sci. 2005 Jun;50(6):1136-40.
Rosiglitazone
 Rosiglitazone decreases liver fat and increases
insulin clearance. The decrease in liver fat by
rosiglitazone is associated with an increase in
serum adiponectin concentrations.
 Despite this beneficial effect of TZDs, in certain
individuals however, in addition to increasing fat
mass, TZDs have the potential to exacerbate
underlying hepatosteatosis.
Hepatic iron
 Many patients with NASH have biochemical
evidence of iron overload.
 Yet, it has been suggested that the iron overload
may be a result of hemachromatosis gene
mutation which is ethnic specific and is probably
not seen outside the population of Anglo-Celtic
Caucasian descent.
Uraz S et al., Dig Dis Sci. 2005 May;50(5):964-9.
Inflammatory liver steatosis caused
by IL-12 and IL-18
 Acute fatty degeneration in the liver is caused by
various agents, such as aspirin, valproic acid, and
ibuprofen, that directly inhibit mitochondrial betaoxidation of fatty acid and oxidative
phosphorylation.
 IL-12 and IL-18 may mediate inflammatory
hepatosteatosis through impairment of the
microcirculation, which leads to mitochondrial
dysfunction in hepatocytes.
Kaneda M et al., J Interferon Cytokine Res. 2003 Mar;23(3):155-62.
The Serum Levels of IL-1b, IL-6, IL-8
and TNF-a in Nonalcoholic Fatty Liver
Serum cytokine values of NAFL and control groups.
IL-8 might play a more
important role in the
pathogenesis of liver
steatosis than TNF-a,
IL-1b and IL-6.
Ülyas Tuncer et al., Turk J Med Sci 33 (2003) 381-386
Post-transplant NASH
Re-transplantation
Cirrhosis
NASH
33%
Steatosis
60%
12.5%
Steatosis in chronic hepatitis B : a result of
metabolic causes attributable to the host
rather than the effect of the viruses.
Comparison of cholesterol and triglyceride levels
of groups with & without steatosis (P<0.05).
Comparison of BMI of groups with & without
steatosis(P<0.05
Altlparmak E et al. Causes of steatosisWorld J Gastroenterol May 28, 2005 Volume 11 Number 20
NASH in patients with HCV
 The presence of NASH in patients with HCV is
strongly associated with:
 Features of the metabolic syndrome
 Is a risk factor for advanced fibrosis with bridging.
 Risk factors for advanced fibrosis in patients with
NASH & HCV are:
 Weight.
 Presence of diabetes.
 Presence and degree of cytological ballooning.
Pathogenesis of NASH
Interruption of insulin signaling
in hepatocytes causes fatty liver.
Increase hepatic FA content
causes hepatic IR
TNF  plays an
important role in IR
evidenced by
improvement of
insulin sensitivity by
genetic disruption of
type 1 TNF receptors
Insulin
resistance (IR)
FFA
- Insulin signaling
-  fat in liver
Bacterial
endotoxins
- TNF
Steatosis
The liver metabolizes FFAs
(partly mediated by lipase
which is inhibited by insulin)
When FFAs accumulate in the liver ,
they are oxidized by mitochondria .
When FFAs accumulation exceeds
oxidation ,the triglycerides and fat
accumulate in the liver
Endotoxins from intestinal bacteria escape into
the mesenteric blood & trigger a sustained
hepatic inflammatory cytokine response (TNF).
Lipid peroxidation
NASH patients have higher concentration of total & FFA
and total saturated & monounsaturated FAs, mainly due to
the increase of: Hexadecanoic acid, Hexadecenoic acid &
Octadecenoic acid. While absolute PUFA was not increased
TNF
Cytokines
Chronic oxidative stress with a) Induction
of certain microsomal enzymes
(cytochrom P450 2 El) b) Lipid
peroxidation. c) Mitochondrial damage
with depletion of mitochondrial glutathion
pools and release of mitochondrial free
radicals which induce lipid peroxidation
of hepatocyte membranes; initiate an
inflammatory response with release of
cytokines (TNF , IL-6, IL- 8) and
stimulate fibrosis.
Steatohepatitis
Iron
TGF-
Cytokines
Cirrhosis
Reduced antipyrine clearance (Cl-AP (reflects
hepatic microsomal oxidative capacity)
Hepatic iron may contribute to the pathogenesis
of NASH by : 1- Induction of lipid peroxidation of
organelle membranes resulting in membrane disruption.
2- Impaired mitochondrial oxidative metabolism. 3Hepatocyte injury and death. 4- Lipocyte activation and
stimulation of collagen type I gene activation & fibrosis.
Clinical Features of NASH
Symptoms
o Vague (fatigue, malaise, right upper quadrant discomfort)
o Variable
o Mostly absent
Signs
o Hepatomegaly common
o Splenomegaly in some
o Portal HTN unusual
Laboratory values
o Increased AST, ALT typical
o +/2 increased alk. phos., GGT
o Increased cholesterol, triglycerides common
o Increased glucose common
o Viral markers (2)
o Autoantibodies (2)
o Iron studies abnormal sometimes
Imaging
o Fatty liver
Transaminases
 Alanine transaminase (ALT) levels are higher than
aspartate transaminase (AST) levels in most
instances.
 AST level may occasionally be higher than the
ALT level, especially in the presence of cirrhosis.
 The usual AST/ALT ratio is < 1 in patients with
NASH and may be used to differentiate it from
alcoholic liver disease (> 2 in the latter).
 NASH can present with normal ALT values (in 2025% of patients) despite the presence of a full
histologic spectrum.
Symptoms of obstructive sleep apnea
in patients with nonalcoholic fatty liver
disease
 Approximately one-half of NAFLD patients,
whether NAFL or NASH, have Syndrome of Sleep
Apnea.
Singh H et al., Dig Dis Sci. 2005 Dec;50(12):2338-43.
Demonstration of fat in
the liver, staging & grading
 The presence of fat in the liver can be
demonstrated by various imaging modalities;
however, no current noninvasive method can
distinguish NASH from NAFLD.
 Liver biopsy remains the gold standard for staging
and grading
Histologic criteria

There are 2 histologic patterns of NASH:

Steatosis.

Steatohepatitis

The principle histologic features of NASH are:

The presence of macrovesicular fatty change in hepatocytes

Displacement of the nucleus to the edge of the cell.

Leucocytic infiltration in steatohepatitis.
Imaging
 Transabdominal ultrasound is a sensitive,
noninvasive method for detecting NAFLD. However,
diagnostic criteria are highly operator-dependant
and non-standardized
 Spleen-minus-liver attenuation difference (DeltaS-
LA) derived from CT shows a good correlation with
the pathology of hepatosteatosis.
Duman DG et al., Dig Dis Sci. 2006 Feb;51(2):346-51.
Scintigraphy
 Using scintigraphy, a strong, significant inverse
correlation between the severity of steatosis,
hepatic triglycerides content, and 99mTcmebrofenin uptake rate was observed.
 In the future, noninvasive "dynamic" breath tests
may disclose specific alterations in metabolic
pathways.
Proposed Histologic Spectrum NAFLD
Fat
+
Inflammation
Stage II
Fat
Inflammation
Ballooning
Degeneration
Fat
Ballooning
Degeneration
Fibrosis
+/-Mallory Bodies
Stage IV
Stage III
Stage I
FAT
Matteoni et al, Gastroenterol 1999
Examples of non-alcoholic fatty liver disease (NAFLD)
NASH as a Cause of End-Stage Liver
Disease
 Primary indication for OLT in 31/1,207 (2.6%) of
patients evaluated at Mayo between 1993-98.
 16/546 (2.9%) underwent transplantation for endstage NASH
OLT= Organ Liver Transplant
Charlton et al. Liver Transpl, 2001
Current Management & Future
Therapy for NASH
Current Management



Weight loss
Treatment of diabetes &
lipid disorders
Avoid Ethanol & hepatotoxic drugs
Potential Future Therapy



Constraining macrophage activation
 Antioxidants (vitamin E, glutathione
pro-drugs)
 Antibiotics (gut decontamination)
 Anti-cytokines (anti-TNF
antibodies, soluble receptors)
Protecting hepatocyte ATP stores
 PPAR agonists
Minimizing Cyp2E1 activity
 Dietary modification (avoid fats)
NASH and effect of weight loss
 Histological & laboratory improvement occurs
with a 10% decrease in body weight.
 However, in some patients, rapid weight loss may
result in mild increase in inflammatory lesions
(hepatitis), despite the regression of steatosis.
This may result from rapid mobilization of fatty
acids or cytokines from adipose tissue, especially
visceral fat.
Silymarin
 Therapeutic approaches include silymarin, the seed
extract of milk thistle, which is a mixture of
flavonolignans
 A hepatoprotective agent stimulating secretion of
adiponectin.
 This flavanoid has also antioxidant, antifibrotic, and
membrane-stabilizing effects.
Schuppan D et al., Hepatology 1999;30:1099-1104
Vitamin E & Betaine
 Vitamin E, an antioxidant agent, reduces liver
inflammation and necrosis.
 Betaine, a naturally occurring choline metabolite,
improves both biochemical parameters and liver
histology.
Metformin
 Metformin improves biochemical indices of
hepatocellular injury and insulin resistance
 Long-term metformin (500 mg 3 times /day for 4
months) resulted in:
 Reduced transaminase levels, which returned to normal in
50% of actively-treated patients.
 Improved insulin sensitivity
 Decreased liver volume by 20%.
 Mechanism of action of metformin in NASH:
 Inhibits the hepatic TNF- activity .
 Inhibits the expression of UCP-2 .
PPAR Agonists
 Thiazolidinediones reduce hepatic fat stores in
type 2 diabetes mellitus.
 PPAR-alpha agonists exert antioxidative effects by
inducing antioxidant enzymes, in addition to
diminishing steatosis
Insulin therapy
 Insulin therapy improves hepatic insulin sensitivity
 It slightly but significantly reduces liver fat content,
independent of serum adiponectin.
Patients receiving long-term total
parenteral nutrition
 Patients receiving long-term total parenteral
nutrition may develop NAFL partially because of
choline deficiency.
 Besides, bacterial overgrowth is enhanced in the
resting intestines.
 Choline supplementation has been reported to
improve or revert hepatic steatosis.
Buchman AL et al., Gastroenterology 1992; 102:1363-1370
Buchman AL,et al. Hepatology 1995;22:1390-1403
Pappo I et al., J Clin Res 1991;51:106-112
Freud HR rt al., J Surg Res 1985;38: 356-363
Iron depletion
 Hepatic iron overload is frequent in NAFLD, and iron
depletion improves liver function tests and insulin
resistance.
 The addition of iron depletion therapy to standard
diet/exercise reduces serum ALT levels in NASH
independently from iron stores, thus representing a
promising effective, safe, and low-cost therapy.
Glucagon-like peptide-1
 Glucagon-like peptide-1 (GLP-1), reverses hepatic
steatosis.
Fat-reduced diet
 Protecting hepatocytes ATP stores & inhibiting
Cyp2E1 activity by dietary modifications (fatreduced diet), may be beneficial in NAFLD patients.
Chavin K et al., J Biol Chem 1999;274:5692-5700
Cortez-Pinto H et al., JAMA 1999;282:1659-1664
Weltman MDet al. Hepatology 1998;27:128-133
Surgical treatment (gastroplasty) improves
metabolic abnormalities & hepatic lesions of
NAFLD in long-term observations
Diffuse grade 3 steatosis &
steatohepatitis in liver biopsy
taken during gastroplasty.
H&E ×250.
Significant improvement of
histologic lesions 8 months
after gastroplasty. H&E ×250.
K. JASKIEWICZ et al. , Digestive Diseases and Sciences, Vol. 51, No. 1 (2006), pp. 21–26
Take Home Message
 The main risk factors for steatosis are obesity, type 2
diabetes & dyslipidemia
 Ethnic & gender differences have important
implications for the development of steatosis-related
liver disease.
 Met. syndrome & adiponectin concentrations are
independently associated with the probability of
steatosis
 Intestinal bacterial overgrowth has been suggested to
play a pathogenic role in patients with nonalcoholic
fatty liver disease (NAFLD).
 Hepatic iron may contribute to the pathogenesis of
NASH
Take Home Message
 IL-12 and IL-18 may mediate inflammatory
hepatosteatosis
 Approximately one-half of NAFLD patients, have
SOSA.
 The most common abnormality in liver function tests is
a two- to fivefold elevation in ALT and AST
 Liver biopsy remains the gold standard for staging and
grading
 Transabdominal ultrasound is a sensitive, noninvasive
method for detecting NAFLD. However, diagnostic
criteria are highly operator-dependant and non
standardized
Take Home Message
 Current management includes weight loss, treatment of
diabetes and lipid disorders as well as avoidance of
alcohol and hepatotoxic drugs.
 Weight loss (about 10%) improves biochemical &
histological profiles in the majority of obese NASH
patients
 Potential future therapies include constraining
macrophage activation using antioxidants, the use of
antibiotics, anti-cytokines & PPAR agonists. Lastly
minimizing Cyp2E1 activity by dietary modification.
 Iron depletion therapy reduces serum ALT levels in NASH
& may be a promising low cost, future therapy.
Thank You !