Chronic Inflammation

When does chronic inflammation occur

Acute inflammation fails to eliminate the stimulus

After multiple episodes of acute inflammation

Secondary to unique biochemical characteristics including virulence factors of the stimulus

Mechanisms of chronic inflammation

persistence/resistence or unresponsiveness

Isolation in tissue

Autoimmunity

Idiopathic

Characteristics of chronic inflammation

Walled off exudate-abscess

Walled off stimulus within granuloma/pyogranuloma

Fibrosis

Prescence of certain leukocytes

Lymphocytes in chronic inflammation causes what

A swelling or mass effect

Th 1 lymphocytes play a role in what?

Foreign body reactions and immune responses to endogenous antigens as well as intracellular pathogens

Part of cell-mediated adaptive immune response

Classic pathway-proinflammatory, anti-tumoral, tissue injury

Th2 lymphocytes are seen with what?

Chronic allergic reactions—> mast cells, eosinophils

Part of humoral adaptive immune response

Play a role in extracellular parasites

Alternative Pathway

What is the star player of chronic inflammation?

What does it do?

Macrophages

Bridges innate and adaptive immune response as an APC and key role in tissue repair

Role of eosinophils in chronic inflammation

accompanied by granulomatous inflammation that infiltrate in dense sheets, grossly forming plaques, and wrap around collagen causing degeneration

When do abscesses form?

When acute inflammation fails to eliminate stimulus

What is an abscess

a collection of neutrophils mixed with cell debris and a fibrous capsule that eventually walls off infection and requires lancing

What type of cell predominates with granulomatous

Macrophages

Factors determining granulomatous inflammation ensues

Inciting agent

Host immune response

Interplay of inflammatory mediators

uncommon idiopathic forms

nodular/tuberculoid granulomatous are arranged how

in discrete nodules/masses ± necrotic center

Diffuse/lepromatous granulomatous have macrophages arranged how

in discrete sheets, poorly demarcated and widespread distribution

Ex: Paratuberculosis

Johne’s disease

Pyogranulonatous are a collection of what

neutrophils and macrophages

Lymphoplasmacytic includes

thick Sheets or nodules of lymphocytes and plasma cells that are seen in inflammatory bowel disease in cats/dogs

What is classic example of neoplastic transformation

injection site sarcomas in cats

What is sclerosis

a specific type of fibrosis in which tissue is replaced by firm fibrous connective tissue after injury or inflammation

What is rodent ulcer

oral plaque on upper lip around philtrum causing swelling of region with variable ulceration