Pathology of extracellular matrix and connective tissue
Dr. Radina IvanovaDr. Radina Ivanova
Associate Professor of PathologyAssociate Professor of PathologyMedical University of SofiaMedical University of Sofia
Pathology of extracellular matrix and connective tissue
Abnormal accumulations in the extracellular matrix – types.
Disorders in the metabolism and structure of the collagen.
Disorders in the content of the proteoglycans.
Fibrinoid change in the extracellular matrix. Hyaline change in the extracellular matrix.
Pathology of extracellular matrix and connective tissue
Amyloid deposition in the extracellular matrix. Types of amyloidosis.
Generalized systemic amyloidosis. Localized amyloidosis. Special staining
methods. Tincture properties of the amyloid. Morphology of amyloid deposition. Deposition of calcium in the extracellular
matrix. Deposition of urates in the extracellular
matrix.
Extracellular matrix
It consists of: the interstitial matrix between cells basement membranes underlying epithelia and
surrounding vessels The ECM serves several important functions:
It provides mechanical support to tissues (collagens and elastin)
It acts as a substrate for cell growth and the formation of tissue microenvironments
It regulates cell proliferation and differentiation proteoglycans bind growth factors and display them at high
concentration, and fibronectin and laminin stimulate cells via cellular integrin receptors
An intact ECM is required for tissue regeneration if the ECM is damaged, repair can only be accomplished by
scar formation.
Extracellular matrix 3 basic components of ECM
fibrous structural proteins such as collagens and elastins, which confer tensile strength and recoil
fibrillar and nonfibrillar BM - nonfibrillar collagen type
IV water-hydrated gels such as
proteoglycans and hyaluronan, which permit lubrication
glycosaminoglycans (dermatan sulfate and heparan sulfate)
adhesive glycoproteins that connect the matrix elements to one another and to cells
fibronectin Laminin Integrins
Abnormal accumulations in the extracellular matrix - types.
Disorders in the metabolism and structure of the collagen.
Disorders in the metabolism and structure of the elastins.
Disorders in the content of the proteoglycans Abnormal accumulations in the ECM
Proteins Fibrinod Hyalin Amyloid
Inorganic substances Ca Urates
Disorders in the metabolism and structure of the collagen
Increased collagen synthesis (fibrosis)
Abnormal structure of collagen Abnormal collagenolysis
Increased collagen synthesis
= Fibrosis (sclerosis) Fibroblasts, myofibroblasts,
smooth mucle cells Van Gieson – collagen - red
activity of lysyl-oxidase Types
Substitutive Heart - cicatrix post MI Liver cirrhosis – chronic
hepatitis Intestitial
Pulmo – in chronic left-sided heart failure (induratio fusca pulmonis)
Abnormal structure of collagen
Genetic defects in collagen structure Marfan’s syndrome Ehlers-Danlos syndrome
Marfan’s syndrome Autosomal dominant disorder of connective tissues, the
basic biochemical abnormality affects fibrillin 1. Which is the major component of microfibrils found in the
extracellular matrix, component of elastins Mutations in the FBN1 gene, which maps to chromosome
15q21. Morphology
Skeleton Arachnodactyly, hyperextensibility of joints, spinal deformities,
such as kyphoscoliosis, deformed chest Eyes
bilateral dislocation or subluxation cardiovascular system
aneurysmal dilation and aortic dissection Regurgitation of mitral valve, congestive heart failure
Ehlers-Danlos syndromes
There are six variants of Ehlers-Danlos syndromes, all caused by defects in collagen synthesis or assembly
30 distinct types of collagen, and all of them have characteristic tissue distributions and are the products of different genes
the clinical heterogeneity of EDS can be explained by mutations in different collagen genes
Deficiency of the enzyme lysyl hydroxylase Deficient synthesis of type III collagen resulting from mutations
affecting the COL3A1 gene conversion of procollagen type I to collagen, resulting from a
mutation in two type I collagen genes (COL1A1 and COL1A2) Clinical features are:
fragile, hyperextensible skin vulnerable to trauma hypermobile joints rupture of internal organs like colon, cornea, and large
arteries Wound healing is poor
Abnormal collagenolysis
activity of collagenlytic enzymes Collagenasess
activity of anticollagenases 1- antitrypsin, 1- anticollagenase
1- antitrypsin defficiency an autosomal recessive disorder
marked by abnormally low serum levels of this protease inhibitor
synthesized predominantly by hepatocytes
The AAT gene, chromosome 14, very polymorphic, and at least 75
forms have been identified PiZZ genotype) have circulating AAT
levels that are only 10% of normal levels
marked cholestasis with hepatocyte necrosis in newborns, to childhood cirrhosis, or to a chronic inflammatory hepatitis
PAS stain of liver -red cytoplasmic granules
Disorders in the metabolism and structure of the elastins
Decreased elastogenesis Aging – wrinkles Ectasia of the aorta Senile emphysema
Increased/abnormal elastogenesis=elastosis Senile elastosis –skin Endocardial fibroelastosis
Newborn – left heart ventriculus Aged – right heart ventriculus, carcinoid syndrome
Disorders in the content of the proteoglycans
Impaired proteoglycans’ synthesis Abnormal collagen-proteoglycan
complexes Free proteoglycans accumulate water
tissue swelling mucous appearance Localised
Pretibial myxedema – Bazedow’s disease Generalised
in myxedema (thyroid hypofunction), due to disposal of hondroit-sulfates
Mucoviscidosis
Mucoviscidosis (cystic fibrosis)
Autosomal recessive defect, which leads to lack of a membrane component essential to proper chloride transport across membranes of the mucus-producing exocrine glands and epithelium of respiratory, gastrointestinal tract and pancreas
CFTR, chromosome 7 Viscous secretion in exocrine glands
The disease is named for changes in the pancreas and mucous salivary glands, which have their ducts plugged by viscous mucus, "Cysts" form behind the plugs, and "fibrosis" ensues after years of obstruction.
Clinical features Pancreas and other exocrine glands (bile, duodenum) Pulmo – the bronchial lumens become plugged by super-thick
mucus, there are often lung infections, pneumonias, lung abscesses, bronchiectasis
sweat glands – salty sweat, (chloride is not reabsorbed through the sweat ducts)
Mucoviscidosis pancreatis
Abnormal accumulations in the ECM
Organic substances –mainly proteins Fibrinod Hyalin Amyloid
Inorganic substances Ca Uric acid
Fibrinoid change in ECM
Fibrinoid Morphologic description of non-structured
substance With various chemical composition, mainly plasma
proteins (albumin, globulins, fibrin) Specific staining –positive reaction for fibrin (by Veigert),
yellow – by Van Gieson for fibrosis Concomitant inflammatory reaction
Fibrinoid necrosis In presence of necrotic cells Outcome - cicatrix
Fibrinoid change in ECM Finrinoid in
precipitation of immune complexes Systemic connective
tissue diseases LE, rheumatoid arthritis,
scleroderma and others Localization
skin different organs (ren,
heart, joints) vessels
Rheumatoid arthritis-subcutaneous nodule
- Fibrinoid necrosis and inflammatory reaction
Fibrinoid change in ECM Finrinoid in insudation
of plasma proteins Malignant hypertension
Endothelial cells of small arteriae and arterioles
hyperplastic arteriolosclerosis
Smooth muscle cell hyperplasia and basement membrane duplication
Arterioles have an "onion skin" appearance
Malignant nephrosclerosis
- Fibrinoid necrosis and inflammatory
reaction
Fibrinoid change in ECM
Finrinoid in focal mucosal necrosis Chronic peptic ulcer
Gastric/duodenal Microscopy – 4
zones Debris Fibrinod necrosis Granulation tissue fibrosis
Hyaline change in the ECM
Hyaline Morphologic description of non-
structured substance With various chemical composition,
mainly proteins Hyalos - transparent, “glassy”
Staining –red by Van Gieson for fibrosis No concomitant inflammatory reaction
Hyaline change in the ECMHyalinosis
Connective tissue hyaline
Hyalinization of collagen fibers in fibrosis
Non-structured, without cells, homogenous, “glassy” tissue
Examples Cicatrices, tumors corpus albicans ovarii, glomeruronephritis lien
Corpus albicans ovarii
Hyaline change in the ECMHyalinosis
Vascular hyaline (hyaline arteriolosclerosis)
DM due to nonenzymatic
glycosylation of proteins in the basement membrane and its leak into the vessel wall
Hypertension Increased intraluminal
pressure pushes plasma proteins into the vessel wall.
Microscopy protein deposits in the
vessel wall, which occludes the lumen
Hyalinosis arteriolarum renis
Amyloid deposition in the ECM
Amyloid Abnormal protein substance, which deposits among
the cells in various tissues and organs (amyloidosis) Microscopy – eosinophilic amorphous deposits, similar
to hyaline But with special stainings
R. Virchov - the term amyloid (amyloss = starch) Tincture properties of the amyloid similar to the starch Cut organ is painted with iodine (red-brown) and
sulfuric acid (dark blue) amyloid binds a wide variety of proteoglycans and
glycosaminoglycans and the presence of abundant charged sugar groups give the deposits staining characteristics that were thought to resemble starch
Amyloid deposition in the ECMSpecial staining methods. Metilviolet and cresylviolet
– red staining (metachromasia)
Congo red – red staining under light microscopy
Congo red - apple-green birefringence under polarized light
Tioflavin S – yellow-green fluorescence
Immuhohistochemistry
Pathogenesis of amyloid deposition
Amyloidosis is a disorder of protein misfolding Abnormal folding of normal or mutant proteins
Amyloid is not a structurally homogeneous protein, although it always has the same morphologic appearance
more than 20 (at last count, 23) different proteins can aggregate and form fibrils with the appearance of amyloid
all amyloid deposits are composed of nonbranching fibrils, 7.5 to 10 nm in diameter, each formed of β-sheet polypeptide chains that are wound together
Main types of amyloid proteins Amyloid light chain (AL)
Derived from light chains (e.g., Bence Jones protein) Amyloid-associated (AA)
Derived from serum associated amyloid (SAA), an acute phase reactant
β-Amyloid (Aβ) Derived from amyloid precursor protein (protein
product of chromosome 21) Endocrine amyloid (AE)
Pathogenesis of amyloid deposition
The deposition of these proteins may result from:
excessive production of proteins that are prone to misfolding and aggregation
mutations that produce proteins that cannot fold properly and tend to aggregate
defective or incomplete proteolytic degradation of extracellular proteins
Types of amyloidosis Amyloidosis is a condition associated with a number of inherited and
inflammatory disorders in which extracellular deposits of fibrillar proteins are responsible for tissue damage and functional compromise.
Generalized Systemic Primary amyloidosis (AL amyloid disposition, associated with multiple myelomas) Secondary (reactive) - AA amyloid, associated with chronic inflammation (e.g.,
rheumatoid arthritis, tuberculosis) Hereditary (autosomal recessive disorder involving AA amyloid (e.g., familial
Mediterranean fever) Localized (confined to a single organ, e.g., brain)
Generalized systemic amyloidosis
Primary amyloidosis AL amyloid disposition Associated with immunocyte dyscrasias- multiple myeloma
(30% of cases), some B-cell lymphomas Secondary (reactive)
AA amyloid Associated with chronic inflammation -rheumatoid arthritis,
tuberculosis Similar tissue involvement in both primary and secondary
types Renm liver, heart, GIT
Hereditary Autosomal recessive disorder involving AA amyloid (e.g.,
familial Mediterranean fever) in individuals of Armenian, Sephardic Jewish, and Arabic origins a febrile disorder characterized by attacks of fever
accompanied by inflammation of serosal surfaces, including peritoneum, pleura, and synovial membrane.
Localized amyloidosis Amyloid nodules
AL protein Nodular deposits of amyloid + plasma cells in pulmo, skin,
tongue Alzheimer's disease
Aβ Endocrine Amyloid
certain endocrine tumors, such as medullary carcinoma of the thyroid gland, islet tumors of the pancreas, pheochromocytomas, and undifferentiated carcinomas of the stomach
in the islets of Langerhans – DM type 2 diabetes Amyloid of Aging
Senile systemic amyloidosis in elderly patients (usually in their 70s and 80s
With dominant involvement and related dysfunction of the heart
Senile cerebral
Morphology of amyloid deposition
Histologically, the amyloid deposition is always extracellular it begins between cells, often closely
adjacent to basement membranes
WHERE? BLOOD VESSEL WALLS, at first KIDNEY SPLEEN LIVER HEART
Amyloidosis of the kidney Grossly
may appear unchanged it may be abnormally large, pale,
gray, and firm; in long-standing cases, the kidney
may be reduced in size. Microscopically amyloid deposits
are found in: in the glomeruli
diffuse or nodular thickenings of the basement membranes of the capillary loops
total obliteration of the vascular tuft in the interstitial peritubular tissue
frequently associated with the appearance of amorphous pink casts within the tubular lumens
in the walls of the blood vessels of all sizes
often causing marked vascular narrowing.
Amyloidosis of the kidney HE, MV
Amyloidosis of the spleen Grossly
often causes moderate or even marked enlargement (200-800 gm)
firm in consistency, and cut surfaces reveal pale gray, waxy deposits.
• Microscopically – 2 patterns of amyloid deposits are found in:
in the splenic folliculi producing tapioca-like granules
on gross examination in the interstitial peritubular tissue
in the splenic sinuses and splenic pulp
forming large, sheetlike deposits "lardaceous spleen"
Amyloidosis of the spleenHE, MV
Amyloidosis of the liver Grossly
may cause massive enlargement (as much as 9000 gm).
the liver is extremely pale, grayish, and waxy
Microscopically amyloid deposits are found in
in the space of Disse they encroach on the adjacent
hepatic parenchyma and sinusoids
The trapped liver cells undergo compression atrophy and are eventually replaced by sheets of amyloid
normal liver function may be preserved even in the setting of severe involvement
Amyloidosis of the heart Grossly
The deposits may not be evident on gross examination,
or they may cause minimal to moderate cardiac enlargement.
There are gray-pink, dewdrop-like subendocardial elevations, particularly evident in the atrial chambers.
Microscopically amyloid deposits are found
throughout the myocardium between myocardial fibers and eventually causing their
pressure atrophy
Amyloidosis of the other organs
The adrenals, thyroid, and pituitary amyloid deposition begins in relation to stromal and
endothelial cells and progressively encroaches on the parenchymal cells.
In the gastrointestinal tract amyloid may be found at all levels, sometimes producing
tumorous masses that must be distinguished from neoplasms.
Nodular depositions in the tongue may produce macroglossia
On the basis of the frequent involvement of the gastrointestinal tract in systemic cases, gingival, intestinal, and rectal biopsies serve in the diagnosis of suspected cases
In patients receiving long-term dialysis deposition of β2-microglobulin amyloid occurs most
commonly in the carpal ligaments of the wrist, resulting in compression of the median nerve (carpal tunnel
syndrome).
Common Types of Amyloidosis and Associated Clinical Findings
Type of Amyloidosis Clinical Findings
Primary andsecondary
Nephrotic syndrome, renal failure (common cause of death)Arrhythmia, heart failureMacroglossia, malabsorptionHepatosplenomegalyCarpal tunnel syndrome
Prognosis
Techniques used to diagnose amyloidosis
Immunoelectrophoresis (to detect light chains) in primary amyloidosis
Tissue biopsy (e.g., adipose, rectum)
subsequent Congo red staining is the most important tool in the diagnosis of amyloidosis
Deposition of calcium in the ECM
Calcification - calcium salts Dystrophic - in dead or dying
tissues Local causes – any type of necrosis
Atherosclerosis, LN (tbc), heart valves
Metasatic – in hypercalcemia Systemic causes
Hyperparathyroidism Renal failure destruction of bone vitamin D-related disorders
affects the interstitial tissues of the vasculature, kidneys, lungs, and gastric mucosa.
Macroscopy fine white granules or clumps
Microscopy intracellular and/or extracellular
basophilic deposits
Deposition of urates in ECM
Gout a disorder caused by the
tissue accumulation of excessive amounts of uric acid
result from overproduction of uric acid, reduced excretion, or both
recurrent episodes of acute arthritis, formation of large crystalline aggregates called tophi, chronic joint deformity
primary (90%) and secondary forms
Morphology of Gout Acute arthritis is characterized by a
dense neutrophilic infiltrate permeating the synovium and synovial fluid.
Long, slender, needle-shaped monosodium urate crystals are frequently found in the cytoplasm of the neutrophils as well as in small clusters in the synovium.
The synovium is edematous and congested, and contains scattered mononuclear inflammatory cells.
Chronic tophaceous arthritis evolves from repetitive precipitation of
urate crystals during acute attacks. The synovium - hyperplastic, fibrotic, and
thickened by inflammatory cells Severe cases - juxta-articular bone erosions.
fibrous or bony ankylosis Tophi
They can appear in the articular cartilage of joints and in the periarticular ligaments, tendons, and soft tissues, including the ear lobes, nasal cartilages, and skin of the fingertips.
Superficial tophi can lead to large ulcerations of the overlying skin.
Gouty nephropathy multiple renal complications associated with
urate deposition medullary tophi, intratubular precipitations, or
free uric acid crystals and renal calculi Secondary complications such as
pyelonephritis can occur, especially when there is urinary obstruction.
Gouty tophus -an aggregate of dissolved urate crystals is surrounded by reactive fibroblasts, mononuclear inflammatory cells, and giant cells