Periostin is a protein produced by cells and secreted into their immediate surroundings, an area known as the extracellular matrix. This matrix provides structural support, and periostin functions within it like cellular glue or scaffolding, helping to organize and strengthen tissues. The production of this protein is dynamic, as its levels can increase in response to physical stress or injury, playing a part in how the body adapts and heals.
Periostin’s Function in Body Tissues
Periostin is involved in the development and maintenance of skeletal tissues. It was first identified in the periosteum, a dense layer of connective tissue covering the outer surface of bones, where it contributes to bone growth, strength, and fracture repair. Its functions also extend to dental health, as it is found in the periodontal ligament that anchors a tooth’s root to the jawbone, maintaining stability.
The protein is a component of the body’s natural repair mechanisms, especially in skin. While present at low levels in healthy skin, its production increases at injury sites to aid in organizing collagen fibers, which is fundamental for tissue regeneration and wound closure. An absence of adequate periostin can impede the healing process and delay skin repair.
Beyond injury repair, periostin contributes to the long-term integrity of connective tissues under constant mechanical stress, such as heart valves and tendons. In healthy heart valves, it is localized to the subendothelial layer, where it supports the valve’s structure and function under the pressures of blood flow.
The Connection Between Periostin and Disease
The same healing properties that make periostin useful can become detrimental when its production is continuous or excessive, a common feature in chronic diseases. In these situations, the protein’s role shifts from repair to driving pathology, where its persistent activity leads to harmful tissue changes.
Elevated periostin levels are linked to certain allergic and inflammatory diseases, particularly a subtype of severe asthma called Type 2 or eosinophilic asthma. In the airways of these patients, inflammatory signals trigger cells to overproduce periostin. This contributes to tissue remodeling, which includes thickening of the airway walls and increased mucus production, narrowing the airways and making breathing difficult.
Periostin is also implicated in cancer progression. Some tumors exploit the protein to create a supportive microenvironment that facilitates their growth and spread (metastasis). By binding to receptors on cancer cells, periostin can trigger pathways that enhance cell survival, invasion into nearby tissues, and the formation of new blood vessels. This has been observed in malignancies like breast, lung, and pancreatic cancers.
The protein is a factor in fibrosis, the formation of excessive scar tissue in organs. For example, after a heart attack, sustained periostin expression can lead to stiff scarring that impairs the heart’s ability to pump blood. It also contributes to fibrosis in the lungs and kidneys and the thickening of heart valves, which can disrupt blood flow.
Medical Applications of Periostin
The presence and quantity of periostin in the body are clinically relevant, making it useful for diagnosis and treatment. Its most established application is as a biomarker, a measurable substance that indicates a particular disease state. Measuring periostin levels provides specific insights into a patient’s condition.
A simple blood test can measure circulating periostin, and this is useful in the management of severe asthma. High levels of the protein in the blood can identify patients with the specific subtype of Type 2 inflammation. This helps predict which individuals may benefit from medications known as biologics, which target the specific inflammatory pathways driving their disease. This biomarker is also under investigation for its potential in heart failure and certain cancers.
Researchers are exploring periostin as a therapeutic target. The goal is to develop drugs that can block the protein’s activity, thereby halting its harmful effects in chronic diseases. These therapies aim to prevent or reduce fibrosis in the heart and lungs, calm airway inflammation in asthma, and slow tumor metastasis. While this research is promising, these treatments are largely in experimental stages and not yet widely available.