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Why can loss of blood flow cause inflammation in tissues?

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Pathways of complement activation — inflammation The main function of complement proteins is to aid in the destruction of pathogens by piercing their outer membranes (cell lysis) or by making them more attractive to phagocytic cells such as macrophages (a process known as opsonization). Some complement components also promote inflammation by stimulating cells to release histamine and by attracting phagocytic cells to the site of infection.

The premise that loss of blood flow causes inflammation is accurate. Inflammation is a protective physiological response to tissue damage, and it can be triggered when tissues die due to a lack of essential oxygen or nutrients, a condition often resulting from restricted blood flow.1

When blood flow to an area is reduced or prevented—a state known as stagnant hypoxia—the affected cells may suffer injury or death. This tissue damage acts as a stimulus for the inflammatory process.21

In a typical inflammatory response, the body initially experiences a brief period of vasoconstriction followed by vasodilation, which increases blood flow to the site of injury. However, when inflammation is triggered by the death of tissue due to ischemia (loss of blood flow), the body is responding to the cellular damage caused by that deprivation. This process is distinct from the vascular changes that occur during an active immune response, where the body intentionally increases blood flow to deliver white blood cells and proteins to the site of injury.31