Chapter 1: The inflammatory Response Flashcards
What cells produce TNF-α?
Activated M1 macrophages are a major source of TNF-alpha.
Also made by:Monocytes, macrophages, neutrophils, NK cells, and several others (T, B, fibroblasts).
What is stimulated by the release of TNF-α?
Production of proinflammatory cytokines (e.g., IL-6), reactive oxygen intermediates, chemotaxins, and endothelial adhesion molecules (all facilitate the recruitment of cells at the site of inflammation).
The main effect of TNF-α is stimulation of cytokines (IL-6, ROS, etc.) that facilitate cell recruitment at the site of inflammation. What are three additional effects of TNF-α?
Activation of natural killer cells, proliferation of cytotoxic T-cells, and T-cell apoptosis.
What are released from the cell surface to reduce the activity of TNF-α?
Tumor necrosis factor soluble receptors
Found constitutively at low levels in the blood but are increased in inflammatory conditions such as sepsis. The solubilized receptors bind to TNF-α and effectively reduce the cytokine’s activity.
TNF-α has both beneficial and deleterious effects. Name some of each:
Beneficial - protects against mycobacterial infection, blocking it in septic patients increases mortality
Deleterious - causes all the classic signs of shock (hypotension, metabolic acidosis), causes inflammation (inflammatory diseases like Crohns).
What is TNF-α?
A membrane-bound surface protein, cleaved by metalloproteases, that is released in soluble form.
Corticosteroids and recombinant TNFR receptors (Enbrel, a treatment for RA/Crohn’s) inhibit TNF-α, which increases risk of what?
Recrudescence of pulmonary mycobacterial infections and infectious complications after orthopedic surgeries.
True or False: Activated M1 macrophages produce proinflammatory cytokines (IL-1β, IL-6, and TNF-α) and prostaglandins, enhancing the inflammatory response?
True
True or False: M2 macrophages are activated in response to proinflammatory cytokines?
False. M2 macrophages are activated in response to anti-inflammatory cytokines (IL-4, IL-13, and IL-10). They then secrete growth factors like PDGF or TGF-β, which stimulate fibroblasts to produce collagen, aiding in wound healing and further dampening the inflammatory response.
True or False: M1 macrophages are activated by infectious agents or proinflammatory cytokines?
True. M1 macrophages are activated by infectious agents or proinflammatory cytokines (interferon-gamma [IFN-γ] or TNF-α). They then produce more proinflammatory cytokines and prostaglandins to increase inflammation.
As the acute inflammatory response resolves, macrophages produce factors that stimulate fibroblasts to produce ________, aiding in wound repair and healing of the inflamed tissue?
Collagen! Fibroblasts are the most common cell that produce collagen.
Prostaglandins are produced in the __________ pathway?
Prostaglandins are produced in the cyclooxygenase (COX) pathway.
What is the starting molecule for prostaglandins?
Arachidonic acid (metabolized along the cyclooxygenase pathway containing COX enzymes).
COX-2 expression is induced by what?
Trauma, growth factors, proinflammatory cytokines, and other mediators.
True or False: COX-1 is constitutively expressed (always present)?
True. It is involved in homeostasis and is present in the majority of mature cells.