Introduction
The skin barrier is characterized by its composition and complex architectural organization with an
adjustable permeability. The peripheral nervous system is involved in skin homeostasis. Its role in
the regulation of the barrier function is not established. The purpose of this study was to identify
the involvement of sensory skin neurons in the modulation of the expression of the junction proteins
involved in the skin's barrier function.
Materials and methods
The analyses were performed on primary human keratinocytes cultured with or without neural
supernatants and skin explants cultured with or without sensory neuron from rats from dorsal root
ganglia (DRGs). The supernatants came from DRG cultures, rat pheochromocytoma cell lines and
differentiated human stem cells. On these cultures we carried out transcriptomic studies by RTqPCR
of junction proteins (Zonula occludens 1 (ZO1), Zonula occludens 2, E Cadherin, Junctional
Adhesion Molecula, Claudin 1, Claudin 2, Claudin 3, Desmocollin 1, Desmoglein) and keratinocyte
differentiation protein such as kallikrein, 6, kallikrein 7, loricrin and involucrin. Protein expression
was explored by immunocytochemistry and immunohistochemistry for Zonula occludens 1 and
Claudine 1. The permeability of skin explants was evaluated by the Lucifer Yellow test.
Results :
In RT-qPCR, there was a statistically significant increase in transcripts of claudine1 of 56 (p=0.03,
n=7), ZO1 of 2.6 (p=0.02, n=7), desmocolline of 2.6 (p= 0.04, n=7) and loricrine of 3.4 (p=0.25,
n=4) among all genes under all conditions after 48 hours of cultivation with DRG compared with
controls. In immunocytochemistry, claudine1 appeared membrane on keratinocytes cultured with
DRG and nuclear in the control. In immunohistochemistry, zonula occludens 1 and claudine 1
proteins were more expressed in the basal layers of the epidermis in the presence of DRG.
Conclusion :
The interaction between keratinocytes and DRG-type neurons in vitro promotes membrane
expression of keratinocyte intercellular junction proteins and modifies tissue and cellular
expression.

The involvement of neurons/keratinocytes interactions in the expression of the junction proteins involved in the skin barrier function.