PTX3 - Pentraxin 3 | Elisa - Clia - Antibody - Protein

Background:

Pentraxin 3 (PTX3) is a member of the pentraxin family of proteins, which are characterized by their cyclic multimeric structure and their ability to recognize and bind to various targets, including pathogens, damaged cells, and extracellular matrix components. PTX3 is an essential component of the innate immune system and plays important roles in inflammation, host defense, tissue repair, and regulation of the immune response. PTX3 is a long pentraxin, meaning it has an extended structure compared to short pentraxins like C-reactive protein (CRP). It is composed of five identical subunits arranged in a pentameric ring structure. Each subunit contains a conserved C-terminal domain known as the pentraxin domain, which is responsible for ligand binding, and a unique N-terminal domain involved in oligomerization and interaction with other proteins. PTX3 is produced and secreted by various cell types, including immune cells (such as macrophages, dendritic cells, and neutrophils), endothelial cells, fibroblasts, and certain epithelial cells, in response to inflammatory stimuli, microbial infection, and tissue injury. Its expression can be induced rapidly following activation of innate immune receptors or exposure to pro-inflammatory cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α).PTX3 plays a critical role in innate immunity by recognizing and binding to a wide range of microbial pathogens, including bacteria, fungi, and viruses. It acts as a soluble pattern recognition receptor (PRR) that opsonizes pathogens, promotes their clearance by phagocytic cells, and activates the complement system to enhance immune responses against invading microorganisms. PTX3 is also involved in the regulation of inflammation by modulating the activity of immune cells, such as macrophages, neutrophils, and dendritic cells. It can amplify inflammatory responses by promoting cytokine production and leukocyte recruitment to sites of infection or tissue damage, but it also has anti-inflammatory effects by limiting excessive inflammation and tissue damage.PTX3 contributes to tissue repair and remodeling following injury or infection by promoting angiogenesis, extracellular matrix remodeling, and wound healing. It stimulates the proliferation and migration of endothelial cells, enhances tissue regeneration, and supports the resolution of inflammation.

Protein Structure:

• Composition: PTX3 is a glycoprotein composed of 381 amino acids.
• Domains: The protein consists of:
• N-terminal Domain: This region is unique to long pentraxins and is involved in the specific binding to ligands and cells.
• C-terminal Pentraxin Domain: This domain is conserved among pentraxins and is responsible for the typical pentraxin fold, facilitating the binding to pathogens and complement activation.
• Oligomerization: PTX3 typically forms a decamer, which is essential for its functional activity.

Classification and Subtypes:

• Family: PTX3 belongs to the long pentraxin subfamily, distinct from the short pentraxins like CRP and SAP.
• Subtypes: There are no subtypes of PTX3, but it shares structural and functional similarities with other pentraxins.

Function and Biological Significance:

• Innate Immunity: PTX3 is an essential component of the humoral arm of innate immunity. It recognizes and binds to various pathogens, including bacteria, fungi, and viruses, facilitating their clearance.
• Inflammatory Response: PTX3 is rapidly produced in response to pro-inflammatory cytokines such as IL-1β and TNF-α, as well as microbial recognition through Toll-like receptors (TLRs).
• Complement Activation: PTX3 can activate the classical pathway of the complement system by binding to C1q, enhancing pathogen opsonization and clearance.
• Tissue Remodeling: PTX3 plays a role in tissue repair and remodeling by interacting with extracellular matrix components and modulating the activity of growth factors and enzymes involved in matrix degradation.
• Angiogenesis: It also has a role in the regulation of angiogenesis, contributing to the control of new blood vessel formation in various physiological and pathological conditions.

Interactions:

• Pathogens: PTX3 binds to a range of pathogens, including Aspergillus fumigatus, Neisseria meningitidis, and Pseudomonas aeruginosa, among others.
• Complement System: It interacts with components of the complement system, particularly C1q and Factor H, to regulate complement activation.
• Extracellular Matrix: PTX3 binds to components of the extracellular matrix, such as fibronectin and hyaluronic acid, influencing tissue remodeling processes.
• Receptors: PTX3 interacts with receptors on immune cells, including Fc receptors and TLRs, to modulate immune responses.

Clinical Issues:

• Inflammatory Diseases: Elevated PTX3 levels are associated with various inflammatory and infectious diseases, such as sepsis, rheumatoid arthritis, and cardiovascular diseases. It serves as a biomarker for the severity and prognosis of these conditions.
• Cancer: PTX3 expression is altered in certain cancers, and it may play a role in tumor progression and metastasis. Its levels can correlate with tumor-associated inflammation and angiogenesis.
• Cardiovascular Diseases: PTX3 has been implicated in the pathogenesis of cardiovascular diseases, including atherosclerosis and myocardial infarction, due to its role in inflammation and vascular function.
• Reproductive Health: PTX3 is involved in female fertility, with roles in the architecture of the cumulus oophorus and in embryo implantation.

Summary:

Pentraxin 3 (PTX3) is a multifunctional protein that plays a crucial role in innate immunity, inflammation, and tissue remodeling. Structurally distinct from the short pentraxins CRP and SAP, PTX3 is produced by various cell types in response to inflammatory stimuli and microbial recognition. It facilitates pathogen recognition and clearance, activates the complement system, and modulates immune cell activity. Clinically, PTX3 is a valuable biomarker for inflammatory diseases, infections, and cardiovascular conditions. Its involvement in cancer progression and reproductive health further underscores its broad biological significance and potential as a therapeutic target.