Tuft cell
Tuft Cells
Tuft cells are a specialized type of epithelial cell found in various tissues throughout the body, including the intestines, airways, and taste buds. They are characterized by their unique morphology, featuring a prominent apical tuft of microvilli extending into the lumen of the tissue. These microvilli are densely packed and often associated with signaling molecules.
Function
Tuft cells are primarily involved in chemosensory transduction, acting as sentinels that detect chemical signals in their environment. Upon stimulation by specific ligands, tuft cells release mediators that activate nearby cells, initiating downstream immune or physiological responses. They play a critical role in:
- Immune Response: In the intestines and airways, tuft cells are important for detecting parasitic infections and initiating type 2 immunity, characterized by the release of cytokines such as IL-25, IL-13, and leukotrienes. These cytokines activate downstream immune cells, such as innate lymphoid cells (ILCs) and eosinophils, to combat the infection.
- Taste Perception: In taste buds, tuft cells contribute to the detection of umami and potentially other taste modalities.
- Tissue Homeostasis: Tuft cells may also play a role in maintaining tissue homeostasis and regulating cell growth and differentiation in their surrounding microenvironment.
Morphology and Markers
Besides the apical tuft, tuft cells exhibit other characteristic features. They possess large, ovoid nuclei and abundant cytoplasm. Several molecular markers are used to identify tuft cells, including:
- Doublecortin-like kinase 1 (DCLK1): A commonly used marker for tuft cells.
- Cytokeratin 18 (KRT18): An epithelial marker often expressed in tuft cells.
- G protein-coupled receptor T1R3 (Tas1r3): Expressed in tuft cells of the taste buds, involved in umami taste detection.
- Transient receptor potential cation channel M5 (TRPM5): A signaling molecule downstream of taste receptors.
Distribution
Tuft cells are found in a range of epithelial tissues including:
- Small intestine
- Colon
- Airways (trachea, bronchi)
- Taste buds
- Gallbladder
- Pancreatic ducts
Their distribution varies depending on the tissue and the species.
Clinical Significance
Dysregulation of tuft cell function has been implicated in various diseases, including:
- Inflammatory bowel disease (IBD): Changes in tuft cell number and activity have been observed in IBD.
- Asthma: Tuft cells contribute to the pathogenesis of asthma by promoting type 2 inflammation in the airways.
- Cancer: The role of tuft cells in cancer is complex and may vary depending on the type of cancer.
Further research is ongoing to fully elucidate the function of tuft cells in health and disease.