lecture 17 Flashcards
liver disease 2
What do you need to have fibrosis?
necrosis and inflammation which stimulates fatty stellate cells to start laying down collagen
What is alcoholic hepatitis?
Characterised histologically by:
- steatosis
- zone 3 ballooning (hydropic swelling) of hepatocytes and presence of Mallory bodies
- zone 3 spotty necrosis and inflammation (clusters of neutrophils and mononuclear cells)
- zone 3 activation of HSC with perisinusoidal collagen deposition and central perivenous fibrosis with or without obliteration of central veins
- fibrosis progressing to micronodular cirrhosis
pathway to cirrhosis in alcoholic liver disease
What do you see in alcoholic hepatitis?
- ballooned hepatocytes
- mallory bodies
- spotty necrosis/necro-inflammation with clusters of neutrophils
Why are the cells enlarged in alcoholic hepatitis?
- acetaldehyde leads to cytoskeletal and mitochondrial damage
- in the liver the intermediate filaments are cytokeratin 8 and 18: give shape to the liver cell and control where the various organelles sit within the cytoplasm
- also contractile actins that give contractility to the faces of plasma membrane facing the sinusoids (helps create pits where they can take in stuff?), also around the biliary canaliculus they help propel bile into the groove
- microtubules help transport proteins/fats/vesicles etc around the cell
- acetaldehyde causes the cytoskeleton to collapse and aggregates to form mallory bodies
- acquire certain other proteins e.g. ubiquitin, Hsp62, CK8/18
- can’t transport proteins out either so intracellular osmotic pressure raised - cell swells up to several times its normal size, becomes rounded and eventually dies
Why is the central vein lost?
- structure of the central vein dependent on the cells around it
- don’t have an independent wall
- if the hepatocytes disappear the framework for the central vein and the sinusoids collapses
- central vein obliterated
- you get complete disorganisation of the vasculature
- -> bridging portal tracts and central zones surrounding and isolating nodules of regenerating liver cells (fibrosis)
What is liver disease associated with the metabolic syndrome?
- non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)
- alcoholic-like liver injury in a non-drinker
- mostly middle-aged women (80%)
- asymptomatic with other medical problems (obesity, diabetes, hypertension)
- enzyme elevations/hepatomegaly
- underlying cause – metabolic syndrome and insulin resistance
How do we diagnose metabolic syndrome?
- central obesity - waist circumference Europid men ≥ 94cm and women ≥ 80cm; asian men ≥ 90cm and women ≥ 80cm
- plus any two of the following 4 factors:
- raised serum TG level: ≥ 1.7mmol/L
- reduced serum HDL cholesterol <1.29mmol/L in females
- raised BP: systolic ≥130 or diastolic ≥85mmHG
- raised fasting blood glucose (FBG) ≥ 5.6mmol/L
How does central obesity lead to a metabolic and inflammatory cascade?
- complex dyslipidemia: high TG, SD-LDL, low HDL
- systemic inflammation
- endothelial dysfunction
- hypertension
- disordered fibrinolysis
- obstructive sleep apnoea
- atherosclerosis
- polycystic ovary syndrome
- NAFLD/NASH
- Type-2 DM
- insulin resistance
What is the histological spectrum of NAFLD in the metabolic syndrome?
similar to alcoholic liver disease but proportion of patients in the categories of increasing severity differs:
- 70% of patients have steatosis alone or steatosis with non-specific inflammation
- 25% develop non-alcoholic steatohepatitis (NASH)
- 3-5% get cirrhosis (less often than with alcohol)
- < 0.5% develop cirrhosis with HCC (less often than with alcohol)
What are hereditary/genetically determined disorders?
- storage diseases
- hereditary iron overload (genetic haemochromatosis) (common in Australia) (tends to manifest in adolescence, adulthood)
- wilson’s disease (copper)
- alpha-1-antitrypsin deficiency (protease inhibitor, PI) (big cause in children)
- other (tyrosinaemia, glycogen storage disease, galactosaemia, etc)
- CF of the pancrease (childhood)
What are types of liver injury?
- toxic
- metabolic
a) acquired
b) hereditary (storage diseases) - hepatitic
a) infectious (viral hepatitis)
b) immunological (autoimmune hepatitis) - cholestatic (bile not getting out)
- circulatory (cardiac failure)
- neoplastic (cancer)
What is the hepatitic pattern?
- the hepatitic histological pattern is defined as diffuse inflammation of the liver accompanied by features of hepatocellular injury and regeneration of hepatocytes
- hepatic pattern is seen in:
1) viral hepatitis
2) idiosyncratic reactions to therapeutic drugs
3) autoimmune
What is the morphology of the hepatitic pattern?
Parenchymal degeneration and cell death
- ballooning degeneration of hepatocytes
- apoptosis – programmed cell death
- necrosis – various types depending on severity
Inflammatory and mesenchymal reaction
- mononuclear inflammatory reaction in lobules and portal tracts
- hardly ever neutrophils
- Hyperplasia of Kupffer cells
- collections of macrophages containing ceroid and iron pigment at sites of necrosis
Regeneration of hepatocytes
- hypertrophy and mitotic replication of hepatocytes
What can be viewed histologically in acute viral hepatitis?
- lobular disarray and inflammation
- liver cell plates are disordered
- mononuclear cells
- hard to see central vein
- ballooning degeneration and apoptosis of hepatocytes
- collections of pigmented macrophages filled with ceroid demarcating foci of liver cell necrosis (diastase stain)
What kills the cells?
- often the immune reaction to the cell carrying the virus as opposed to the virus itself
What happens after around 6 weeks?
- fast resolving
- liver cells start to go back to their regular arrays
- central vein visible
- sinusoids visible
- residual inflammation remains in the portal tract
- still might be some pigmented macrophages in zone 3