This document summarizes inflammation and its key aspects. It describes inflammation as the body's protective response to eliminate injurious agents, damaged tissues, and necrotic cells. The signs of inflammation are heat, redness, swelling, pain, and loss of function. There are two major components of acute inflammation - vascular changes that increase blood flow and permeability, and cellular events involving leukocyte recruitment and activation through phagocytosis. Chronic inflammation is characterized by infiltration of mononuclear cells, plasma cells, tissue destruction, repair, and fibrosis over prolonged periods.
2. Survival of all organisms requires they
eliminate:
• foreign invaders (infectious pathogens: viruses,
bacteria, fungi)
• damaged tissues
• Achieved via a complex mechanism
called “inflammation”
3. Inflammation is a protective response
intended to eliminate the initial cause of cell
injury as well as the necrotic cells and
tissues resulting from the original insult
5. A double edge sword?
Although inflammation helps clear infections
and other noxious stimuli and initiates
repair, the inflammatory reaction and the
subsequent repair process can cause
considerable harm.
8. 2 additional signs seen in acute inflammation
• Pain (dolor)
• Loss of function (function laesa)
9. Steps of Inflammation
5R’s
1. Recognition of injurious agent
2. Recruitment of leukocytes
3. Removal of agent
4. Regulation of the response
5. Resolution
12. Acute Inflammation
rapid response to injury or microbes and
other foreign substances that is designed to
deliver leukocytes and plasma proteins to
sites of injury
13. Stimuli
can be triggered by a variety of stimuli
• Infections
• Trauma
• Physical & chemical agents
• Foreign bodies
• Immune reactions
17. Changes in Vascular
Caliber and Flow
• Changes in blood vessels begin rapidly
after infection or injury but may develop
at variable rates, depending on the
nature and severity of the original
inflammatory stimulus.
25. 3. transmigration between endothelial cells;
4. migration in interstitial tissues toward a
chemotactic stimulus
26.
27. Leukocyte activation
• Once leukocytes have been recruited to
the site of infection or tissue necrosis,
they must be activated to perform their
functions
28. • Stimuli for activation include microbes,
products of necrotic cells, and several
mediators
29. Phagocytosis
Consists of 3 distinct but interrelated
steps
1. recognition and attachment of the particle to the
ingesting leukocyte
2. engulfment, with subsequent formation of a phagocytic
vacuole
3. killing and degradation of the ingested material.
31. Patterns of acute
inflammation
• vascular and cellular reactions that
characterize acute inflammation are
reflected in the morphologic appearance
of the reaction
33. serous
characterized by:
• the outpouring of a watery
• relatively protein-poor fluid that,
depending on the site of injury
34. fibrinous
• occurs as a consequence of more severe
injuries,
• resulting in greater vascular permeability
that allows large molecules (such as
fibrinogen) to pass the endothelial barrier
35. suppurative
• manifested by the presence of large
amounts of purulent exudate (pus)
consisting of neutrophils, necrotic cells,
and edema fluid
36. • Abscesses are focal collections of pus
that may be caused by seeding of
pyogenic organisms into a tissue or by
secondary infections of necrotic foci.
38. Chemical mediators of
inflammation
• Mediators may be produced locally by
cells at the site of inflammation,
• or may be circulating in the plasma as
inactive precursors that are activated at
the site of inflammation
42. Chronic Inflammation
• is inflammation of prolonged duration
(weeks to months to years) in which
active inflammation, tissue injury, and
healing proceed simultaneously.
45. Chronic inflammation arises in the following
settings:
1. T lymphocyte-mediated immune
r e s p o n s e c a l l e d d e l a y e d - t y p e
hypersensitivity
2. Immune-mediated inflammatory diseases
3. autoimmune diseases
46. Chronic Inflammatory
Cells and Mediators
• fundamental feature of chronic
inflammation is its persistence
• results from complex interactions
between the cells that are recruited to
the site of inflammation and are activated
at this site
47. Macrophages
• dominant cell of chronic inflammation
• derived from circulating blood monocytes
• act as filters for particulate matter,
microbes, and senescent cells, as well as
acting as sentinels
48. • scattered in most connective tissues,
• also found in organs such as the liver
• spleen and lymph nodes
• central nervous system
• lungs
49. • Together these cells comprise the so-
called mononuclear phagocyte system,
also known by the older name of reticulo-
endothelial system
50.
51. Lymphocytes
• mobilized to the setting of any specific
immune stimulus
• as well as non-immune-mediated
inflammation
52.
53. Eosinophils
• characteristically found in inflammatory
sites around parasitic infections
• or as part of immune reactions mediated
by IgE, typically associated with allergies.
54. Mast cells
• sentinel cells widely distributed in
connective tissues throughout the body,
• participate in both acute and chronic
inflammatory responses
• "armed" with IgE antibody specific for
certain environmental antigens
55. • Neutrophils are the classic hallmarks of
acute inflammation, many forms of
chronic inflammation may nevertheless
continue to show extensive neutrophilic
infiltrates