Weekly reads: cool olfactory tuft cells, T-cell therapy, NK cells

There’s a fascinating type of olfactory cell. These so-called tuft cells have unusual characteristics, especially for nose cells. I had never heard of them before until reading a new article.

Olfactory epithelium, Olfactory histology
An H&E image of Olfactory epithelium (left) and respiratory epithelium (rght). Many cell types are present in both epithelia including tuft cells that act as sensors.

The inside of the nose may not seem like a very attractive place but there are cool “nose stem cells” in there.  More broadly, there is all kinds of interesting biology going on in the olfactory epithelium. There are more cell types than we might have realized too and the system of smell is quite sensitive. Many of us found this out the hard way during COVID with some loss of sense of smell or taste. That seems to be due in part to injury to the supportive or sustentacular cells.

I’ve been reading up more about the cells in the nose since becoming a professor. This is mainly because in the Histology class that I help teach here at UC Davis School of Medicine, we teach about the microanatomy of the inner nose. At the same time, I’ve been growing concerned about intranasal delivery of unproven stem cells at clinics. When delivered that way, some of the cells could end up in the brain.

Let’s go into the new article on tuft cells.

Olfactory stem & tuft cells

A nasal cell atlas reveals heterogeneity of tuft cells and their role in directing olfactory stem cell proliferation, Science Immunology. This is an intriguing paper cataloging many kinds of nose cells. Beyond the stem cells, there are different kinds of the nasal tuft cells. These amazing cells act as chemical sensors and can impact nearby stem cell and other cell behavior. Tuft cells have roles in various respiratory diseases.

Why do I think tuft cells are so cool? They have taste receptors rather than olfactory receptors. While it seems your nose cannot taste things in the same sense as your tongue because tuft cells do not appear to directly send information to the brain, the cellular ‘tasting’ by tuft cells does influence cells around them. This impact includes regulating nearby olfactory neuron function. Thus, perhaps indirectly the tuft cell “tasting” of the environment can lead to unique signals going to the brain via influence on neighboring neurons.

It seems hard to identify nasal tuft cells visually such as by H&E staining. Still such H&E images of the nasal epithelium are quite striking. I’ve included one above from the Histology class.

To ID tuft cells you need to use immunostaining. There are cousin cells in the intestine that are also called tuft cells and express their own repertoire of taste receptors.

Other recommended reads

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