2. Out comes of Acute Inflammation
May have one of three outcomes:
1. Complete resolution
2. Healing by fibrosis
3. Chronic inflammation
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3. Out comes of Acute Inflammation
May have one of three outcomes:
1. Complete resolution
2. Healing by fibrosis
3. Chronic inflammation
This occurs when:
• There is persistence of injurious agent
• There is interference with normal healing
process
Eg: Peptic ulcer, Complicated pneumonia
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5. Chronic Inflammation
• It’s inflammation of prolonged duration
(weeks or months)
• Here tissue injury, and attempts at repair
coexist
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11. Chronic Inflammation
ROLE OF MACROPHAGES
The macrophage is the dominant cellular player in chronic
inflammation
Macrophages are one component of the mononuclear
phagocyte system
The half-life of blood monocytes is about 1 day, whereas
the life span of tissue macrophages is several months
or years
Emigrate into extravascular tissues quite early in acute
inflammation, and within 48 hours
Extravasation is governed by: Adhesion molecules &
chemical mediators
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13. Chronic Inflammation
ROLE OF MACROPHAGES
Macrophages may be activated by a variety of
stimuli:
Microbial products binding with TLRs
Cytokines (e.g., IFN-γ) and
other chemical mediators
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14. Chronic Inflammation
ROLE OF MACROPHAGES
The products of activated macrophages
1. serve to ELIMINATE injurious agents &
2. to initiate the process of REPAIR
3. responsible for much of the TISSUE INJURY
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15. Chronic Inflammation
ROLE OF MACROPHAGES
Activation of macrophages results in:
1. increased levels of lysosomal enzymes
2. reactive oxygen and nitrogen species
3. production of cytokines, growth factors
4. other mediators of inflammation
5. Some of these products are toxic to microbes
and host cells
6. Cytokines, chemotactic factors
7. Growth factors – PDGF, Angiogenesis
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21. Chronic Inflammation
OTHER CELLS IN CHRONIC INFLAMMATION
Plasma cells:
• Develop from activated B lymphocytes
• Produce antibodies
• Abs may act against persistent foreign or self
antigens
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22. Chronic Inflammation
OTHER CELLS IN CHRONIC INFLAMMATION
Eosinophils:
• Immune reactions mediated by IgE
• Parasitic infections
• Chemokine that recruits EØ is eotaxin
• Eosinophilic granules that contain major basic protein
• MBP is toxic to parasites
• EØs are of beneficial in controlling parasitic infections, but
they contribute to tissue damage
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23. Chronic Inflammation
OTHER CELLS IN CHRONIC INFLAMMATION
Mast cells:
Widely distributed in connective tissues
Participate in acute and chronic inflammations
Mast cell receptor (FcεRI) binds Fc portion of IgE
Degranulation – releases histamine and prostaglandins
Allergic reactions – sometimes fatal - anaphylactic shock
Secrete a plethora of cytokines
Have the ability to both promote and limit inflammatory
reactions in different situations
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25. GRANULOMATOUS
INFLAMMATION
• It’s a distinctive pattern of chronic
inflammation
• Seen in some infectious and noninfectious
conditions
• It’s an attempt to contain an offending
agent that is difficult to eradicate
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27. Granuloma
Def: A granuloma is a focus of chronic
inflammation consisting of a microscopic
aggregation of macrophages that are
transformed into epithelium-like cells,
surrounded by a collar of mononuclear
leukocytes, principally lymphocytes and
occasionally plasma cells.
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28. Granuloma
Components:
Epithelioid cells: have a pale pink granular
cytoplasm with indistinct cell boundaries, often
appearing to merge into one another. The
nucleus is oval or elongate, and may show
folding of the nuclear membrane (boomarang)
Giant cells: Epithelioid cells fuse to form giant cells
in the periphery or sometimes in the center of
granulomas. - Langhans-type giant cell / foreign
body–type giant cell
Older granulomas develop an enclosing rim of
fibroblasts and connective tissue
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29. Granuloma
Types:
There are two types of granulomas, which
differ in their pathogenesis:
1. Foreign body granulomas Eg: Silica
2. Immune granulomas Eg: TB
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