Cells of Acute Inflammation, Chemical Component of Inflammation

What are the cells of Acute Inflammation?

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• Eosinophil

• Platelets

• Neutrophils

• Macrophages

• Mast Cells

• Basophil

• Endothelial cells

What is the Mast cell and their activated function?

The Mast Cell is the most important cellular activator of the inflammatory response

• Activated function: release of granules containing histamine and active agents

• Resides in the skin, gut and respiratory tract

What are Neutrophils and their activated function?

Neutrophils are the first on scene (within 90 minutes)

• Activated function: contains PRRs (pattern recognition receptors) that bind onto microbes for phagocytosis

What do Neutrophils produce?

Neutrophils produce ROS and proteases to kill bacteria, and vasoactive mediators, cytokines and chemokines

What are macrophages and their activated function?

Macrophages are resident in some tissues and is the dominant phagocyte later in inflammation (48 hours) and controls the later healing process

• Activated function: Phagocytosis and antigen presentation

What are endothelial cells?

Endothelial cells are specialized cells that form a thin layer in the interior surface of all blood vessels and heart chambers

What do endothelial cells do when they are activated?

When activated, they make leukocyte adhesion molecules, which allow leukocytes to move to sites of damage or infection

• They also produce cytokines such as IL-1 and IL-8

What agents can activate endothelial cells?

Endothelial cells can be activated by bacteria, viruses, cytokines, physical and oxidative stress, and oxidized low density lipoproteins

What are platelets activated by?

Platelets are activated by exposed collagen and clotting factors such as Tissue Factor and Platelet Activating Factor (PAF)

What inflammatory mediators do Platelets produce?

Platelets produce cytokines, chemokines and histamine

What are Basophil’s activated function?

Basophil activated function: release of histamine and other vasoactive cytokines

What are eosinophils?

Eosinophils are a type of white blood cell involved in allergies and parasites

What do eosinophils do in hypersensitivity reactions?

Eosinophils release leukotrienes and other inflammatory mediators, and these chemicals cause inflammation and contribute to allergy symptoms

What are the two main groups in chemicals controlling inflammation?

1. Chemicals produced by the liver and always present in plasma

2. Chemicals produced by the cells

What are the three key protein systems produced by the liver?

1. Clotting proteins / Kinin system

   1. Major kinin: bradykinin, which causes increased vessel permeability and produces pain

2. Complement System

   1. Activation of proteins that either kill pathogens or intensifies reactions of the inflammatory response

3. Acute phase proteins:

   1. Promotes fever, inflammation and leukocyte recruitment and activation such as C-reactive protein (CRP)

What are the three actions of complement?

1. Degranulation of mast cells

2. Opsonization

3. Cytolysis

What are the chemicals produced by cells and what do they do?

1. Histamine

   1. Released during acute inflammation by mast cells, basophils, and platelets

   2. Histamine increases vasodilation and increased capillary permeability

2. Prostaglandins and leukotrienes

   1. Found in cell membranes

   2. Aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) reduce inflammation

What are cytokines? What are some examples of cytokines?

3. Cytokines

   1. Proteins made by many cells to communicate in order to produce an inflammatory response (such as interleukin 1 and tumor necrosis factor - alpha)

   2. Also produced by damaged tissue cells for inflammation

What are the effects of cytokines?

Effects include: increased activity of WBCs, causing endothelial cells to produce adhesion molecules, which stimulate the acute phase response

What are chemokines?

3. Chemokines

   1. A type of cytokine which function as chemoattractants to recruit and direct the migration of immune and inflammatory cells such as IL-8