They play key roles in enabling white blood cells to adhere to the inner surface of blood vessels, migrate out of the blood vessels into the tissue, and be chemotactically attracted to the injured or infected site. They also trigger extracellular killing by neutrophils. The endothelial cells form a fine network of new capillaries into the injured area to supply blood, oxygen, and nutrients to the inflamed tissue. The fibroblasts deposit the protein collagen in the injured area and form a bridge of connective scar tissue to close the open, exposed area. This is called fibrosis or scarring, and represents the final healing stage .
Inflammation is regulated by cytokines .
So as can be seen, acute inflammation is essential to body defense. Chronic inflammation , however, can result in considerable tissue damage and scarring . With prolonged increased capillary permeability, neutrophils continually leave the blood and accumulate in the tissue at the infected or injured site. As they discharge their lysosomal contents and oxidizing agents, surrounding tissue is destroyed and eventually replaced with scar tissue . Anti-inflammatory agents such as antihistamines or corticosteroids may have to be given to relieve symptoms or reduce tissue damage.