pneumotaxin3

Pneumotaxin3, also known as pulmonary surfactant protein D (SP-D), is a protein found in the lung's surfactant system. It plays a crucial role in the innate immune defense of the respiratory tract. SP-D is a large glycoprotein belonging to the collectin family, characterized by collagen-like regions and carbohydrate-binding lectin domains. These lectin domains allow SP-D to bind to various microbial carbohydrates, including those found on bacteria, viruses, and fungi.

The primary function of pneumotaxin3 is to act as a pattern recognition molecule. By binding to pathogens, it can agglutinate them, preventing their attachment to lung cells and facilitating their clearance. SP-D can also opsonize microbes, marking them for phagocytosis by immune cells like macrophages. Furthermore, SP-D has been shown to modulate inflammatory responses, potentially dampening excessive inflammation that could damage lung tissue. Research suggests SP-D may also be involved in lung development and repair processes. Its presence is particularly concentrated in the alveolar lining fluid, where it directly interacts with inhaled substances and microorganisms. Variations in SP-D levels or function have been implicated in various lung diseases, including cystic fibrosis and idiopathic pulmonary fibrosis.