Dialog between skin and its microbiota: Emergence of “Cutaneous Bacterial Endocrinology”

Abstract

The pioneering work of Kaplan and Greenberg [1] led to admit that, as eukaryotic cells, bacteria can communicate. In fact, many multicellular social bacterial behaviours such as swarming type motility, [2] biofilm formation [3] and virulence expression, [4] require population synchronization and that is performed at least partly through a highly regulated cell-to-cell communication system called quorum sensing (QS). QS is based on the bacterial population density, which is performed through secretion and sensing of specific signal molecules named autoinducers. Nowadays, many QS autoinducers, such as the N-acyl homoserine lactones (AHL) and quinolones (Gram-negative

Effect of 17β-estradiol on a Human Vaginal Lactobacillus Crispatus Strain

“…The absence of effect of 17β-estradiol on the growth of L. crispatus CIP104459 is consistent with previous studies showing that human neurohormones and neurotransmitters, including substance P, calcitonin gene related peptide (CGRP), natriuretic peptides, GABA and catecholamines, are generally without effect on the cultivability of commensal bacteria 36 . Conversely, it was demonstrated that steroid hormones, such as estradiol and androstenedione, have an inhibitory effect on the growth of Helicobacter pylori 40 .…”

“…Cutaneous bacteria such as C. acnes were also shown to express sensors for catecholamines (noradrenalin and adrenalin) suggesting that C. acnes acts as a relay between stress and acne 37 . Bacteria even produce small eukaryotic communication molecules such as histamine, glutamine and particularly γ-aminobutyric acid (GABA), which are well-known as eukaryotic communication molecules 36 . GABA is even considered as the universal inter-kingdom communication factor 38 .…”

“…There is now ample evidence that the response of human commensal bacteria to peptidic hormones and neurohormones is essential to skin homeostasis 36 . Cutaneous bacteria such as C. acnes were also shown to express sensors for catecholamines (noradrenalin and adrenalin) suggesting that C. acnes acts as a relay between stress and acne 37 .…”

Towards a renaissance of dermatoendocrinology: Selected current frontiers

“…[7,33,36] With the current Focus Theme Issue dedicated to dermatoendocrinology, Experimental Dermatology continues this proud publication tradition and acknowledges the major advances that this rapidly evolving skin research arena has witnessed over the past decade. We start off with a very thought-provoking "cutaneous bacterial endocrinology" review by Racine et al [37] that portrays an intriguing, Following up on their previous exploration of this topic, [35] Soeberdt et al [38] then provide a pharmaceutical R&D perspective on how compounds that target neuroendocrine signalling in human skin and its appendages may be recruited and repurposed for the management of psoriasis, acne, alopecia areata, hyperhidrosis and atopic dermatitis and which formidable challenges one faces along this path. The editors are convinced that this neuropharmacological approach to dermatoendocrinology, in particular the repurposing of FDA-approved neuropharmacological agents such as naltrexone or aprepitant [39][40][41][42] for dermatological purposes represents one of the most exciting and clinically relevant frontiers in investigative dermatology.…”

“…We start off with a very thought‐provoking “cutaneous bacterial endocrinology” review by Racine et al [37] that portrays an intriguing, bi‐directional communication between the cutaneous neuroendocrine system and the skin microbiome: on the one hand, skin‐derived neuromediators such as substance P, catecholamines and calcitonin gene‐related peptide affect the physiology and virulence of skin‐associated bacteria, while on the other some bacteria can even synthesize and release histamine, glutamate and γ‐aminobutyric acid or peptides with partial homology to neurohormones such as α‐melanocyte‐stimulating hormone (α‐MSH) that interact with cognate receptors expressed by skin cells.…”