Causes of Liver Cirrhosis

1. Alcohol (Alcohol-Related Liver Disease - ArLD)

2. Chronic Viral Hepatitis

• Hepatitis B (HBV): A major cause globally, especially in Asia and sub-Saharan Africa. Treated with nucleoside/nucleotide HBV DNA polymerase inhibitors (tenofovir, entecavir) or pegylated interferon. Long-term antiviral therapy with TDF or entecavir has been shown to result in regression of cirrhosis in ~75% at year 5.
• Hepatitis C (HCV): Previously a leading cause; highly effective direct-acting antivirals (DAAs) have dramatically reduced progression. Successful HCV treatment is the clearest example of fibrosis reversibility in cirrhosis.

3. Metabolic Dysfunction-Associated Steatohepatitis (MASH / NASH)

4. Biliary Diseases

5. Autoimmune Hepatitis (AIH)

6. Inherited / Metabolic Disorders

7. Cardiac / Vascular Causes

• Cardiac cirrhosis (Congestive hepatopathy): Right heart failure or tricuspid regurgitation causes chronic hepatic venous congestion, leading to "nutmeg liver" and ultimately cirrhosis.
• Budd-Chiari syndrome: Hepatic vein thrombosis causing outflow obstruction.
• Veno-occlusive disease (sinusoidal obstruction syndrome): Obliteration of central hepatic venules, often post-bone marrow transplant.

8. Toxic / Drug-Induced

9. Cryptogenic Cirrhosis

10. Less Common Causes

• Schistosomiasis - periportal fibrosis from Schistosoma mansoni or S. japonicum, common in the Middle East, Africa, and South America
• Sarcoidosis - granulomatous hepatitis
• Celiac disease - chronic immune injury
• Thyroid disease (hypothyroidism associated with NAFLD)

Summary Table (Harrison's Classification)

In clinical practice, alcohol and chronic viral hepatitis (B and C) together account for the vast majority of cirrhosis cases worldwide, though MASH is rapidly increasing in prevalence in high-income countries.

Pathophysiology of Hepatic Fibrosis in Cirrhosis

The Normal Liver Architecture (Baseline)

• Hepatocytes (parenchymal cells)
• Sinusoidal endothelial cells (fenestrated, allowing free exchange)
• Kupffer cells (resident macrophages, within the sinusoidal lumen)
• Hepatic stellate cells (HSCs) - quiescent pericytes in the space of Disse (between endothelium and hepatocytes)

Step 1 - Initiation: Hepatocellular Injury

• Apoptosis (programmed cell death)
• Necrosis / sterile necrosis (releasing danger-associated molecular patterns, DAMPs)
• Inflammation (recruitment of neutrophils, monocytes)

Step 2 - Kupffer Cell Activation

• Necrotic debris from injured hepatocytes
• Acetaldehyde and its protein adducts (in alcohol-related disease)
• Lipopolysaccharide (LPS) from gut bacteria arriving via the portal vein, binding Toll-like receptor 4 (TLR4)

• TGF-β1 (transforming growth factor beta-1) - the master profibrogenic cytokine
• Reactive oxygen species (ROS) via NADPH oxidase
• Nitric oxide (NO) via inducible NOS
• PDGF (platelet-derived growth factor)
• Connective tissue growth factor (CTGF)
• Chemokines and other inflammatory mediators

Fig: Hepatocyte injury → Kupffer cell activation → TGF-β and ROS release → Stellate cell stimulation → Collagen + matrix metalloproteinase production → Fibrosis. (Basic Medical Biochemistry, 6e)

Step 3 - Hepatic Stellate Cell (HSC) Activation - The Central Event

• Lose vitamin A lipid droplets - a hallmark morphologic change
• Undergo proliferation (myofibroblast phenotype)
• Develop prominent rough endoplasmic reticulum
• Become contractile (express alpha-smooth muscle actin, α-SMA) - this is why portal hypertension develops; HSCs can physically constrict sinusoids
• Massively upregulate extracellular matrix (ECM) synthesis

Step 4 - Extracellular Matrix (ECM) Overproduction

Step 5 - Matrix Remodeling: The MMPs vs. TIMPs Imbalance

• Matrix metalloproteinases (MMPs) (especially MMP-1) normally degrade type I collagen
• TIMPs (tissue inhibitors of metalloproteinases, esp. TIMP-1) block MMPs
• In chronic injury: TIMP-1 levels rise, MMP-1 activity falls → net collagen accumulation
• 4-hydroxynonenal (lipid peroxidation product) upregulates both procollagen type I and TIMP-1 gene expression simultaneously

Step 6 - Additional Cellular Contributors

• Portal fibroblasts - resident near portal tracts; especially important in biliary cirrhosis (PBC, PSC), where injury starts periportally
• Bone marrow-derived mesenchymal cells - can traffic to the liver
• Epithelial-to-mesenchymal transition (EMT) - hepatocytes or cholangiocytes transdifferentiate into fibroblast-like cells
• Sinusoidal endothelial cells - promote angiogenesis, which releases HSC-activating paracrine signals; new vascular channels within fibrous septa contribute to architectural distortion

Step 7 - Architectural Distortion = Cirrhosis

• Micronodular cirrhosis (nodules <3 mm, often alcoholic)
• Macronodular cirrhosis (nodules >3 mm, often viral)
• Mixed pattern

Fig: A = Normal liver (smooth surface). B = Normal histology (organized sinusoids). C = Cirrhotic liver (orange-tawny, nodular surface). D = Cirrhotic histology (regenerative nodules surrounded by fibrous bands). (Goldman-Cecil Medicine)

1. Portal hypertension - increased resistance to portal flow (both mechanical from fibrous septa + functional from contractile HSC-myofibroblasts constricting sinusoids)
2. Hepatocellular insufficiency - loss of functional hepatocyte mass + impaired sinusoidal exchange

Fibrosis Reversibility

• Successful HCV treatment with DAAs → regression of fibrosis in many patients
• Iron removal in hemochromatosis → fibrosis regression
• Alcohol abstinence in ArLD → variable but meaningful improvement
• Long-term TDF/entecavir in HBV → regression in ~75% at 5 years

Summary Pathway

Chronic Liver Injury (alcohol / virus / metabolic / biliary)
        ↓
Hepatocyte damage → ROS, acetaldehyde, DAMPs
        ↓
Kupffer cell activation → TGF-β1, PDGF, ROS, NO
        ↓
LPS via TLR4 → NF-κB → ↓BAMBI → HSC hypersensitized to TGF-β
        ↓
HSC activation → myofibroblast phenotype
(lose Vit A, gain α-SMA, contractility)
        ↓
↑ Collagen I/III + ECM deposition  +  ↑ TIMP-1 / ↓ MMP-1
        ↓
Net matrix accumulation → bridging fibrosis
        ↓
Regenerative nodules + fibrous septa = CIRRHOSIS
        ↓
Portal hypertension + Hepatocellular failure

Note: Davidson's Principles and Practice of Medicine is not available in the textbook library. The content below is drawn from Yamada's Textbook of Gastroenterology 7e, Sleisenger & Fordtran's GI and Liver Disease, Pye's Surgical Handicraft, and Bailey & Love's Surgery - all of which present the same classical framework. The Davidson's table on causes of pain by abdominal region follows the same structure as below.

Causes of Abdominal Pain by Region

The 9 Regions

┌──────────────────┬──────────────┬──────────────────┐
│ Right             │   Epigastric │  Left             │
│ Hypochondrium     │   Region     │  Hypochondrium    │
├──────────────────┼──────────────┼──────────────────┤
│ Right             │   Umbilical  │  Left             │
│ Lumbar (Flank)    │   Region     │  Lumbar (Flank)   │
├──────────────────┼──────────────┼──────────────────┤
│ Right             │   Hypogastric│  Left             │
│ Iliac Fossa       │   (Pubic)    │  Iliac Fossa      │
└──────────────────┴──────────────┴──────────────────┘

1. Right Hypochondrium (Right Upper Quadrant)

2. Epigastric Region

3. Left Hypochondrium (Left Upper Quadrant)

4. Right Lumbar (Right Flank)

5. Umbilical Region (Periumbilical)

6. Left Lumbar (Left Flank)

7. Right Iliac Fossa (RIF)

8. Hypogastric / Suprapubic Region (Pubic Region)

9. Left Iliac Fossa (LIF)

Extra-Abdominal and Generalised Causes

Key Physiological Principle (Visceral vs. Somatic Pain)

• Foregut (stomach to mid-duodenum, liver, biliary, pancreas, spleen) → Epigastric pain
• Midgut (mid-duodenum to mid-transverse colon, appendix) → Periumbilical pain (e.g., early appendicitis starts central)
• Hindgut (mid-transverse colon to rectum) → Hypogastric/suprapubic pain