patoloji-ders-notlari

Amyloidosis

Serdar Balcı

Amyloidosis

Serdar BALCI, MD

Amyloidosis

• Deposit, accumulation of fibrillar proteins
• Causes are many inherited and inflammatory disorders
• Extracellular deposits of fibrillar proteins
  • responsible for tissue damage and functional compromise
  • Misfolded proteins or protein fragments, normally soluble accumulate
    • Abnormal fibrils

Right conjunctival amyloidosis.

Al-Ola Abdallah, et al. Am J Case Rep. 2012;13:102-105.

Systemic AL amyloidosis

Estelle Desport, et al. Orphanet J Rare Dis. 2012;7:54-54.

Macroglossia due to amyloidosis

Hakan Emmungil, et al. Case Rep Rheumatol. 2014;2014:549641.

A patient with macroglossia

Gavin M. Melmed. Proc (Bayl Univ Med Cent). 2009 July;22(3):280-283.

Amyloid: Amylose (starch) like

• The fibrillar deposits bind
  • proteoglycans and glycosaminoglycans
  • heparan sulfate and dermatan sulfate
  • plasma proteins
  • serum amyloid P component (SAP)
• These charged sugar groups cause staining characteristics resemble starch → That is why they are called amyloid

PATHOGENESIS OF AMYLOID DEPOSITION

Amyloid

• A disorder of protein misfolding
• Not a structurally homogeneous protein
  • more than 25 different protein
• But has same morphologic appearance
  • Composed of nonbranching fibrils
  • 7.5 to 10 nm in diameter
  • Formed of β-sheet polypeptide chains
  • Congo red stain binds to these fibrils and produces a red–green birefringence

Robbins Basic Pathology

Amyloidosis

• Normally misfolded proteins are removed from body
  • Intracellular, proteasomes
  • Extracellular, macrophages
• Misfolded proteins
  • Unstable
  • Self-associate
  • Form oligomers and fibrils
  • Accumulate in tissues
• Disrupt normal function

Proteins that form amyloid

• Normal proteins
  • when they are produced in increased amounts
  • tendency to fold improperly and associate to form fibrils
• Mutant proteins
  • prone to misfolding
  • aggregation

Robbins and Cotran Pathologic Basis of Disease

Rubin’s Pathology 7th Ed

Rubin’s Pathology 7th Ed

AL (amyloid light chain) protein

• Produced by plasma cells
• Made up of
  • Complete immunoglobulin light chains
  • The amino-terminal fragments of light chains
  • Both
• Monoclonal B cell proliferation
• Defective degradation: some light chains are resistant to complete proteolysis

AA (amyloid-associated) fibril

• Pathogenesis:
  • Long standing inflammation
  • IL-6, IL-1
  • SAA (serum amyloid-associated) protein synthesized by liver
  • Increased SAA levels
  • AA form of amyloid deposits
• Proposed mechanisms:
  • An enzyme defect that results in incomplete breakdown of SAA → insoluble AA molecules
  • Genetically determined structural abnormality in the SAA molecule itself → resistant to degradation by macrophages

Aβ amyloid

• Cerebral lesions of Alzheimer disease
• 4-kDa peptide
• The core of cerebral plaques
• The core of amyloid deposits in cerebral blood vessels
• Derived from
  • Larger transmembrane glycoprotein
  • Amyloid precursor protein (APP)

Rubin’s Pathology 7th Ed

Color Atlas of Pathology

Transthyretin (TTR)

• A normal serum protein that binds and transports thyroxine and retinol
• Mutations in the gene alter its structure
  • Misfolding
  • Aggregation
  • Resistant to proteolysis
  • Familial amyloid polyneuropathies
• Senile systemic amyloidosis
  • Heart of aged persons
  • Protein is structurally normal
  • Accumulates at high concentrations

β2-Microglobulin

• MHC class I molecule, normal serum protein
• Aβ2m fibers are structurally similar to normal β2m protein
• Long-term hemodialysis
  • Present in high concentrations in renal disease
  • Not efficiently filtered through dialysis membranes
  • Retained in the circulation
• 60-80% of patients on long-term dialysis developed amyloid deposits
  • Synovium
  • Joints
  • Tendon sheaths

Other proteins

Procalcitonin

Keratin

Prolactin

CLASSIFICATION OF AMYLOIDOSIS

Robbins Basic Pathology

Primary Amyloidosis: Immunocyte Dyscrasias with Amyloidosis

• Systemic
• AL type
• most common
• Monoclonal plasma proliferation
• 5-15% multiple myeloma
• Malignant Plasma Cells
  • synthesize single Ig (monoclonal gammopathy)
    • protein spike on serum electrophoresis
  • synthesize or secrete λ or κ light chain
    • Bence Jones protein
    • excreted in urine

Primary Amyloidosis: No other disease found

Have increased plasma cells in bone marrow

Not enough to cause tumor but increased light chain in serum or urine

Reactive Systemic Amyloidosis (Secondary amyloidosis)

• Systemic
• AA protein
• Secondary to an associated inflammatory condition
• Chronic inflammation
  • Tuberculosis
  • Bronchiectasis
  • Chronic osteomyelitis
  • Autoimmune disease
    • RA
    • Ankylosing spondylitis
    • Inflammatory bowel disease
  • Chronic skin infections
    • “skin-popping” of narcotics
• Tumors
  • Renal cell carcinoma
  • Hodgkin lymphoma

Familial (Hereditary) AmyloidosisFamilial Mediterranean Fever (FMF)

• AA proteins
• Autosomal recessive
• Attacks of fever
• Inflammation of serosal surfaces
• Peritoneum, pleura, and synovial membrane
• Seen in
  • Turkey
  • Armenian
  • Sephardic Jewish
  • Arabic

Gene → pyrin

Protein → component of the inflammasome

Patients have gain-of-function mutations in pyrin → constitutive overproduction of the pro-inflammatory cytokine IL-1 → Persistent inflammation

Familial (Hereditary) AmyloidosisFamilial Amyloidotic Polyneuropathies

Peripheral and autonomic nerves

In different parts of the world

Portugal, Japan, Sweden, United States

Mutant forms of transthyretin (ATTRs)

Hemodialysis-Associated Amyloidosis

Long-term hemodialysis for renal failure

Deposition of β 2 -microglobulin

Could not be filtered and accumulates

Carpal Tunnel Syndrome

New membranes are told to filter these proteins as well

Localized Amyloidosis

• Limited to a single organ or tissue
• Detectable nodular masses or microscopic
• Nodular (tumor-forming) deposits
  • Lung, larynx, skin, urinary bladder, tongue, eye
• Infiltrates of lymphocytes and plasma cells in the periphery
  • Is it a response or are they responsible for it?

Endocrine Amyloid

• Endocrine tumors
  • Medullary carcinoma of the thyroid gland
    • polypeptide hormones
  • Islet tumors of the pancreas
    • islet amyloid polypeptide
  • Pheochromocytoma
  • Undifferentiated carcinomas of the stomach
• Islets of Langerhans, type 2 diabetes mellitus

Color Atlas of Pathology

Medullary carcinoma of thyroid

Color Atlas of Pathology

Amyloid of Aging

• Senile systemic amyloidosis
  • Systemic deposition of amyloid in elderly (70s-80s)
  • Heart (senile cardiac amyloidosis)
    • Restrictive cardiomyopathy
    • Arrhythmias
    • Normal transthyretin
• Mutant form of TTR
  • Typically affecting only the heart
  • 4% of the black population United States are carriers of the mutant allele
  • cardiomyopathy identified in both homozygous and heterozygous

MORPHOLOGY OF AMYLOIDOSIS

Morphology of Amyloidosis

• Small amounts are recognized with iodine and sulfuric acid
  • Reddish (mahogany) brown staining of the amyloid deposits
• Larger amounts
  • Organ is enlarged
  • Tissue appears gray with a waxy, firm consistency
• Histologic examination
  • Amyloid deposition is always extracellular and begins between cells
  • Often closely adjacent to basement membranes
  • As amyloid accumulates, it grows over, surround and destroy the cells
  • AL form, perivascular and vascular localizations are common

Methods to detect amyloid

Eosinophilic amorphous acellular material with H&E

Weakly PAS positive (starch like)

Congo-Red: Apple-green birefringence under polarized light

Crystal violet: __ metachromatic staining__

Electron Microscopy

Immunohistochemistry

Mass Spectrometry-Based Proteomic Analysis

Serum, urine electrophoresis

Genetic mutation analysis

Robbins Basic Pathology

Congo red–stain: Apple-green birefringence under polarized light

Robbins Basic Pathology

Robbins Basic Pathology

Amyloid in Kidney

• **Most common and most serious **
• Grossly
  • Unchanged
  • Abnormally large, pale, gray, and firm
  • In long-standing cases, reduced in size
• Microscopically
  • Glomeruli
    • Focal deposits within the mesangial matrix
    • Diffuse or nodular thickenings of the basement membranes of the capillary loops
    • Grows over capillary lumina
    • Obliteration of the vascular tuft
  • Interstitial peritubular tissue
    • Amorphous pink casts within the tubular lumens
  • Walls of the blood vessels
    • Marked vascular narrowing

Rubin’s Pathology 7th Ed

Amyloid in Spleen

Moderate or even marked enlargement (200 to 800 gm)

Limited to the splenic follicles

Limited to splenic sinuses

Color Atlas of Pathology

Amyloid in Liver

Massive enlargement (9000)

Extremely pale, grayish, and waxy on both the external surface and the cut section

First appear in the space of Disse

Progressively enlarge to encroach on the adjacent hepatic parenchyma and sinusoids

Trapped liver cells undergo compression atrophy

Replaced by sheets of amyloid

Normal liver function may be preserved even in the setting of severe involvement

Rubin’s Pathology 7th Ed

Heart

Systemic involvement

AL form

Isolated form (senile amyloidosis)

older persons

Normal grossly or minimal to moderate cardiac enlargement

Gray-pink, subendocardial elevations, in atrial chambers

Histologic examination

Deposits begin between myocardial fibers cause pressure atrophy

Robbins Basic Pathology

Rubin’s Pathology 7th Ed

Other Organs

• Adrenals
• Thyroid
• Pituitary
• Tongue may produce macroglossia
• Gingival, intestinal, and rectal biopsies are useful in diagnosis
• Abdominal fat aspirates are used for diagnosis
• β2-microglobulin amyloid
  • long-term dialysis
  • carpal ligaments of the wrist
  • compression of the median nerve (carpal tunnel syndrome)

Clinical Course of Amyloidosis

Atrophy

Toxic to neighbour cells

Impair normal organ, tissue function

Depend on organ and severity of involvement

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Amyloid

Proteinaceous substance deposited between cells in various tissues and organs in a variety of clinical settings.

starchlike staining properties, PAS positive

Amorphous, eosinophilic, hyaline extracellular substance

• chemically diverse
• typical physical properties:
  • irrespective of their biochemical composition
  • form nonbranching long fibrils (7.5–10 mm)
  • By electron diffraction, they are arranged into b-pleated sheaths.
  • Congo red staining is typical
  • Under polarized light, Congo red-stained amyloid fibrils show an apple green birefringence.

Amyloidosis

• group of diseases characterized by a deposition of amyloid in various organs
  • as a primary disease
    • in multiple myeloma
  • Secondary
    • during the course of chronic inflammatory or other diseases.
  • may be limited (localized) to a single organ
  • may be systemic
  • may be hereditary

Primary amyloidosis

Systemic deposition of AL-type amyloid

Associated with plasma cell neoplasia and B-cell lymphoma

Monoclonal gammopathy (whole immunoglobulins or only light chains) found by electrophoresis of serum

Secondary systemic amyloidosis

• Underlying disease
  • tuberculosis, chronic osteomyelitis, rheumatoid arthritis, cancer
  • heroin abuse
• Widespread deposition of AA protein in many organs

Amyloidosis of aging

• Systemic deposition of amyloid in elderly
• Frequent involvement of the heart
  • Cardiac amyloidosis

Systemic amyloidosis

• Kidneys
  • Both kidneys enlarged, pale, and waxy
  • Glomerular mesangial, interstitial, and vascular wall depositions
• Spleen
  • **Splenomegaly **
  • nodular (follicular) depositions: sago spleen
  • maplike (red pulp) depositions: lardaceous spleen
• Liver
  • Hepatomegaly
  • extracellular amyloid
  • pressure atrophy of hepatocytes
• Small blood vessels
• Diagnosis may be made by biopsy of tissue
  • fat pad, gingiva, or rectum

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the traditional approaches to therapy focus on treating the underlying disease—specifically, chemotherapy for myeloma (with AL amyloidosis) and antibiotics for chronic infections or anti- inflammatory agents for autoimmune diseases (with AA amyloidosis).

Some breakthroughs appear imminent, however: Building on an improved understanding of protein folding, research has led to production of a number of useful small molecules—so-called “amyloid breakers,” now entering into clinical trial. Some of these interfere with the binding of chaperone proteins such as substance P and apolipoprotein E4 (apoE4), which can propagate the β-sheet content of Aβ peptides and promote pathogenic fibril formation in the brain: CPHPC is a carboxypyrrolidinyl carboxylic acid derivative that binds to the P component and results in its prompt removal from the circulation thus eliminating an important “nucleation factor” for amyloid propagation. Other agents such as tramiprosate inhibit the interactions between interstitial glycosaminoglycans and Aβ that normally stabilize fibril formation; these breakers are sulfated glycosaminoglycan mimetics. Yet another approach is to stabilize native transthyretin tetramers with drugs like tafamadis or diflunisal to prevent the dissociation of monomeric components (e.g., from mutant isoforms) that can then misfold into amyloid fibrils.

With these approaches, coupled with earlier detection of amyloid deposits before irreversible damage is done, what previously has been an intractable and inexorable process may eventually become manageable.

References

Robbins Basic Pathology, 9 th __ Ed, pp:__ 153-154

Pathology Secrets, 3 rd __ ed, pp:74-75__

http://www.mayomedicallaboratories.com/articles/hottopics/2009-12a-amyloidosis.html

Rubin’s Pathology 7th Ed Clinicopathologic Foundations Of Medicine, pp: 563-573

Color Atlas of Pathology, pp:48-54