CD163

CD163

CD163 is a protein that in humans is encoded by the CD163 gene. It is a member of the scavenger receptor cysteine-rich (SRCR) superfamily and is primarily expressed on the surface of monocytes and macrophages. CD163 functions as a scavenger receptor for the hemoglobin-haptoglobin complex, playing a crucial role in the clearance of free hemoglobin from the bloodstream, thereby protecting tissues from oxidative damage.

Structure

CD163 is a transmembrane protein composed of a large extracellular domain, a single transmembrane helix, and a short cytoplasmic tail. The extracellular domain contains multiple SRCR domains, which are responsible for ligand binding. The structure of CD163 allows it to bind to various ligands, including hemoglobin-haptoglobin complexes, bacteria, and other molecules involved in inflammation and immune response.

Function

The primary function of CD163 is to mediate the endocytosis of hemoglobin-haptoglobin complexes. This process is essential for the recycling of iron and the prevention of oxidative stress caused by free hemoglobin. CD163 is also involved in the anti-inflammatory response, as its expression is upregulated by anti-inflammatory cytokines such as IL-10 and glucocorticoids.

CD163 has been implicated in various physiological and pathological processes, including:

• Iron metabolism: By clearing hemoglobin-haptoglobin complexes, CD163 helps maintain iron homeostasis.
• Immune response: CD163 can bind to bacteria and other pathogens, facilitating their clearance by macrophages.
• Inflammation: CD163 expression is associated with the resolution of inflammation, and soluble CD163 (sCD163) levels in the blood can serve as a biomarker for inflammatory diseases.

Clinical Significance

CD163 is a potential biomarker for several diseases, including atherosclerosis, sepsis, and liver disease. Elevated levels of sCD163 have been observed in patients with these conditions, reflecting increased macrophage activation and inflammation.

In addition, CD163 has been studied as a therapeutic target. Modulating CD163 activity could potentially enhance the clearance of hemoglobin and reduce oxidative stress in diseases such as sickle cell disease and hemolytic anemia.

Research

Ongoing research is focused on understanding the role of CD163 in various diseases and its potential as a therapeutic target. Studies are also exploring the use of CD163 as a delivery system for drugs and therapeutic agents, taking advantage of its ability to target macrophages specifically.

Also see

• Monocyte
• Macrophage
• Scavenger receptor
• Hemoglobin
• Inflammation