Kudos to @alazozcan.bsky.social, Tommaso, Yuval and Veronique for their insights and work for this review.

Immune cells are more than aggressors; they are also diplomats that prevent conflict by improving the barrier capacity, the ECM, and the mechanical properties of tissues. We are just beginning to scratch the true impact of immune cells on tissues and overall organismal physiology.

Congratulations for this beautiful study, team! 🔥

Gracias Alejo! 🙏

Thank you Ivan!

Thank you Miryam Naddaf for your beautiful News piece
t.co/ccZDZdhAC5

Big thank you to everyone @CNIC and @VBT_Yale that contributed to this paper with funding, ideas, reagents or just moral support. We owe you.

A final take-home message: In biology, cells are not what they look but what they do. Cell lineages are human divides, and the remarkable plasticity of myeloid cells teaches us that biology works by instructing functional programs at defined times and places.

You can find a lot more details, controls and ideas in the paper
With @alazozcan.bsky.social can we are now exploring if this unconventional matrigenic capacity of immune cells matters in other physiological and pathological contexts… stay tuned for more surprises!

When we created a small wound in the skin, matrix-producing neutrophils would rapidly accumulate around the lesion to build matrix "rings" that protected from small molecules or microbes… magical images from the hands of the master of microscopy Uderhardt and @alazozcan.bsky.social

We interpret that neutrophils complement fibroblasts with their unique migratory properties, and capacity to reach places other cells can’t.

We propose that what is unique to neutrophils is their capacity to dynamically reinforce the matrix: the skin becomes stiffer at night-time, when neutrophils enter the tissue! An experiment from the mind and hands of @TVicanolo !

To demonstrate this, we generated a reporter mouse in which collagens produced by neutrophils (or fibroblasts, for comparison) are labeled with mCherry. Amazing craft by @alazozcan.bsky.social to set this up...

But how do neutrophil mediate this unexpected property of the skin? Although questions remain, we find that they are uniquely specialized in depositing matrix components, such as Collagen 3, in specific areas of the skin where large matrix fibers provide mechanical reinforcement to the skin

An exciting finding was that neutropenic mice, or mice lacking TGF signaling in neutrophils, both have major alterations in the skin: matrix structure, composition and skin mechanics are dramatically altered, resulting in a more permeable skin

We report that neutrophils from the skin (and other epithelial barriers) are unique. They produce matrix components, including collagens and enzymes that remodel the matrix. This program, induced through TGFb signaling, is shared by mice and humans.