36: Chronic Inflammation

Fates of any acute inflammatory event

• Resolution

• Heal and scar

• Become chronic

If an injury results in fibrosis, it is by definition what type of process

Chronic inflammation

Types of tissues that undergo fibrosis when injured

• Labile tissues with severe injury

• Tissues that can’t heal always scar after injury

Why does acute inflammation progress to chronic

When the thing causing the insult is hard to get rid of, or if the normal healing process is impaired

Timeline that defines chronic

3+ weeks

T/F: an injury can only be acute or chronic inflammation

False; it can have layers of acute inflammation bleeding out to chronic inflammation

Primary cell type in chronic inflammation

Macrophages! Also other monocytes (lymphocytes and plasma cells)

Lymphocyte morphology

LARGE nucleus, not a lot of cytoplasm

Plasma cell morphology

Single nucleus, large clear area next to he nucleus where the golgi apparatus lives

Why is it relevant that plasma cells have a large golgi apparatus

It has one job: to pump out Abs

Macrophage morphology

LARGE, oval nucleus and cytoplasm with lots of vacuoles

Two types of macrophages by origin

• Tissue resident macrophages

• Monocyte derived macrophages

What do macrophages detect

MAMPs and DAMPs

Type of eicosanoid primarily produced by macrophages

Prostaglandins

How do macrophages kill engulfed organisms

RNS, some ROS and lysosomes (less than neutrophils)

Acute inflammation cytokines produced from macrophages

• TNF

• IL-1

• Also: IL-6, IL-8

Chronic inflammation cytokines produced from macrophages

IL-12

What do NK cells scan for

MHC I

Key cytokine produced from NK cells

IFN-γ

Function of B lymphocytes

Ab production to fight extracellular pathogens

Function of T lymphocytes

Kills cells to fight intracellular pathogens

Types of activated monocyte derived macrophages

Classical and alternative

Classically activated macrophage

M1, pro-inflammatory induced by PAMPs, DAMPs, and cytokines

Alternatively activated macrophage

M2, anti-inflammatory and pro-wound repair

Types of chronic exudates

Chronic exudates are always cellular

Types of chronic cellular exudates

• Lymphoplasmacytic

• Granulomatous

Components of a lymphoplasmacytic exudate

Lymphocytes and plasma cells

Components of a granulomatous exudate

Epithelioid macrophages and multinucleated giant cells

Granulomatous exudate morphology

Firm, plate tan, often nodular

Pyogranulomatous exudate

Center of dead neutrophils, forming pus