Kamimura, M. | Search bioRxiv

bioRxiv2025

Impact of Low-Dose Narrowband UV Radiation on Skin Tissue and Mast Cells in a Canine Model

Narrowband ultraviolet radiation (NB-UVR) therapy is widely utilized in dermatology worldwide. While the immunosuppressive effects of ultraviolet radiation are well-documented, its non-inflammatory effects remain poorly understood. This study evaluated the effects of sub-minimal erythema dose (MED) narrowband ultraviolet radiation using a canine model. The effects of narrowband-ultraviolet B (310 nm) and A2 wavelengths (320 and 330 nm) were compared. Initially, we demonstrated the therapeutic potential of NB-UVR in dogs with spontaneous atopic dermatitis (n = 6, p < 0.05). Following 300 mJ/cm{superscript 2} sub-MED ultraviolet radiation exposure, intradermal skin testing, skin mast cell counts, and RNA sequencing analysis were conducted. Additionally, cell viability (WST assay) and apoptosis (DAPI staining) were assessed in vitro using a canine mast cell line. Ultraviolet radiation exposure significantly reduced intradermal skin test scores across all wavelengths and decreased skin mast cell counts at 310 nm (n = 3, p < 0.05). In vitro, cell viability was significantly reduced at 310 and 320 nm (p < 0.05), and 310 nm irradiation specifically increased apoptotic cell numbers (p < 0.05). RNA sequencing identified 71 differentially expressed genes at 320 nm, with enrichment analysis highlighting muscle cell components and functions, potentially associated with arrector pili muscle activity. These findings suggest that 310 nm irradiation induces apoptosis, while 320 nm elicits non-inflammatory modulatory effects, highlighting distinct wavelength-specific therapeutic mechanisms of narrowband ultraviolet radiation.

immunology↗

bioRxiv2018

Rapid clearing of biological organs by using phosphoric acid, a hydrophilic solution with high refractive index

Tissue clearing is a fundamental challenge in biology and medicine to achieve high-resolution optical imaging of tissues deep inside intact organs. The clearing methods, reported up to now, require long incubation time or physical/electrical pressure to achieve tissue clearing, which is done by matching the refractive indices of the whole sample and medium to that of the lipid layer. Here we show that phosphoric acid increases the refractive index of the medium and can increase the transparency of formalin-fixed tissue samples rapidly. Immersion of fixed tissues of mice in phosphoric acid solutions increased their transparency within 60 min in the case of 3-mm-thick fixed tissue specimens. While phosphoric acid suppresses bright signals on the boundary of cells in their phase-contrast images, it does not damage the morphology of cell membrane with phospholipid bilayer. The protocol presented herein may contribute to develop better and faster soaking methods for tissue clearing than previously reported protocols.\n\nHighlights{blacksquare} Phosphoric acid can reduce light scattering by tissue samples.\n{blacksquare}Tissue clearing effect of phosphoric acid is fast and needs only 60-min incubation.\n{blacksquare}Cell membrane was preserved during incubation using phosphoric acid.

cancer biology↗