Tuft cell

Tuft cells, sometimes referred to as brush cells, are chemosensory cells in the epithelial lining of the intestines and respiratory tract. The names "tuft" and "brush" refer to the microvilli projecting from the cells.

Ordinarily there are very few tuft cells present but they have been shown to greatly increase at times of a parasitic infection. Several studies have proposed a role for tuft cells in defense against parasitic infection. In the intestine, tuft cells are the sole source of secreted interleukin 25 (IL-25). Tuft cells are differentiated from stem cells in the bases of intestinal glands and their increase is seen as a type-2 immune response via ILC2s, which secrete IL-13, causing an increase in the number of tuft cells. Type 2 immunity is involved in parasitic infections and allergic inflammation.

The presence of α-gustducin in intestinal tuft cells raises the idea that tuft cells may be involved in the taste transduction pathway. Cells also express TRPM5, a signaling molecule in bitter and sweet taste signaling. Mature tuft cells express DCLK1. Tuft cells have also been found to secrete endogenous opioids. The transcription factor Gfi1b has been found to be expressed in tuft cells.

ATOH1 is required for tuft cell specification but not for maintenance of a mature differentiated state, and knockdown of Notch results in increased numbers of tuft cells.

Tuft cells have a pear shape, with a wide base, narrow apex, and a "tuft" of microvilli projecting into the lumen of the organ. Tuft cells can be identified by staining for cytokeratin 18, neurofilaments, actin filaments, acetylated tubulin, and DCLK1 to differentiate between tuft cells and enterocytes.

Tuft cells are found in the intestine, pancreas and the respiratory tract, from nose to alveoli.

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