Sensitive scalp is associated with excessive sebum and perturbed microbiome.

BACKGROUND: Sensitive scalp, one of the most frequent complaints among sensitive skin syndrome, has been described as abnormal and unpleasant sensory reactions of the scalp to environmental stimulus. However, the symptoms are usually objective and hard to diagnose. OBJECTIVE: This study aimed to reveal the biophysical properties and etiology of sensitive scalp. METHODS: Sixty-two healthy female subjects were enrolled and divided into nonsensitive scalp (NS) and sensitive scalp (SS) groups according to questionnaires. Noninvasive instruments were used to measure biophysical properties. Ultra-performance liquid chromatography-tandem mass spectrometry and gas chromatography mass spectrometry were introduced to quantify skin lipids profiles, and 16S rRNA sequencing was used to detect the composition of bacteria. RESULTS: Sensitive scalp showed elevated pH level, more irritated skin, and more fluorescence of porphyrins. Increased sebum production was found in SS group at occiput, among which free fatty acids, cholesteryl ester, and squalene were significantly in higher amount compared with NS. SS also had significantly higher percentage of Propionibacterium, and lower bacterial diversity. CONCLUSIONS: Taken together, sensitive scalp showed disrupted barrier function, abnormal sebum amount and composition, as well as perturbed microbiome, which might be the direct cause. Products targeting these features could be helpful for the treatment of sensitive scalp.

A marketed fermented dairy product containing Bifidobacterium lactis CNCM I-2494 suppresses gut hypersensitivity and colonic barrier disruption induced by acute stress in rats.

BACKGROUND: Fermented milk (FM) containing Bifidobacterium lactis CNCM I-2494 and yogurt strains improves irritable bowel syndrome (IBS) symptoms in constipated IBS patients. In rats, stressful events exacerbate IBS symptoms and result in the alteration of gut sensitivity and permeability via epithelial cell cytoskeleton contraction. In a stress model, we aimed at evaluating the effect of B. lactis CNCM I-2494 as a pure strain or contained in an FM product on visceral sensitivity and the impact of this FM on intestinal barrier integrity. METHODS: Visceral sensitivity was analyzed in rats subjected to partial restraint stress (PRS). Rats received during 15 days the B. lactis as a pure strain (10(6) to 10(10) CFU mL(-1)), B. lactis in an FM product (10(8) CFU g(-1), diluted or not), or a control product. Gut paracellular permeability, colonic occluding and Jam-A proteins, and blood endotoxin levels were determined in rats receiving B. lactis in an FM product submitted or not to a PRS. KEY RESULTS: The FM product showed a dose-dependent inhibitory effect on stress-induced visceral hypersensitivity. A similar antihyperalgesic effect was observed at 10(10) CFU mL(-1) of pure B. lactis administration. The FM product prevented the increase in intestinal permeability induced by PRS and restored occludin and JAM-A expressions to control levels. The FM product abolished the increase concentration of blood endotoxin induced by PRS. CONCLUSIONS & INFERENCES: This study illustrates that a probiotic food containing B. lactis CNCM I-2494 strain reduces visceral hypersensitivity associated with acute stress by normalizing intestinal epithelial barrier via a synergistic interplay with the different probiotic strains and/or metabolites contained in this product.