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Dandruff is a common and challenging complaint associated with type of scalp, skin and population. Scalp seborrheic dermatitis (SD) is a more severe manifestation of dandruff associated with very severe itching and inflammation. Histamine is an interesting biomarker released in scalp affected by dandruff and SD even though the mechanism is not well understood yet. A monocentre clinical study was conducted to confirm the relationship between dandruff/SD and scalp histamine level in an Indian population. Highly sensitive liquid chromatography coupled with mass spectrometry was used for histamine quantification in scalp from samples obtained non-invasively. Results showed that scalps with dandruff and mild to moderate SD had higher histamine levels compared with healthy scalps.

Background Urban pollution is correlated with an increased prevalence of skin pigmentation disorders, however the physiological processes underlying this association are unclear. Objectives To delineate the relationship between polycyclic aromatic hydrocarbons (PAHs), a key constituent of atmospheric pollution, and immunity/skin pigmentation pathways. Methods We exposed peripheral blood mononuclear cells (PBMC) to PAHs and performed cytokines/chemokine profiling. We then examined the effect of immune activation on pigmentation by co-culturing PBMC and Benzo(a)pyrene (BaP) with reconstructed human pigmented epidermis (RHPE). To study the mechanism, we treated keratinocytes with conditioned medium from BaP-exposed PBMC and studied DNA damage responses, aryl hydrocarbon receptor (AhR) activation and pro-pigmentation factor, proopiomelanocortin (POMC) secretion. Results PAHs induced up-regulation of inflammatory cytokines/chemokine in PBMC. Co-culturing of RHPE with PBMC+BaP resulted in increased melanin content and localization. BaP conditioned medium significantly increased DNA damage, p53 stabilization, AhR activation and POMC secretion in keratinocytes. We found that IFNγ induced DNA damage while TNFα and IL-8 potentiated POMC secretion in keratinocytes. Importantly, BaP conditioned medium-induced DNA damage and POMC secretion is prevented by antioxidants vitamin E, vitamin C and sulforaphane, as well as the prototypical corticosteroid dexamethasone. Finally, vitamin C and sulforaphane enhanced the genome protective and depigmentation effects of dexamethasone, providing proof-of-concept for a combinatorial approach for the prevention and/or correction of PAH-induced pigment spots formation. Conclusion Our study reveals the importance of systemic immunity in regulating PAH-induced skin pigmentation, and provide a new keratinocytes DNA damage response mechanistic target for the prevention or reversal of pollution-associated skin pigmentation.