Anti-scratching Behavioral Effects of N-Stearoyl-phytosphingosine and 4-Hydroxysphinganine in Mice

A phytosphingosine derivative mYG-II-6 inhibits histamine-mediated TRPV1 activation and MRGPRX2-dependent mast cell degranulation

BACKGROUND

Phytosphingosine and its derivative are known for their skin-protective properties. While mYG-II-6, a phytosphingosine derivative, has shown anti-inflammatory and antipsoriatic effects, its potential antipruritic qualities have yet to be explored. This study aimed to investigate mYG-II-6's antipruritic properties.

METHODS

The calcium imaging technique was employed to investigate the activity of ion channels and receptors. Mast cell degranulation was confirmed through the β-hexosaminidase assay. Additionally, in silico molecular docking and an in vivo mouse scratching behavior test were utilized.

RESULTS

Using HEK293T cells transfected with H1R and TRPV1, we examined the impact of mYG-II-6 on histamine-induced intracellular calcium rise, a key signal in itch-mediating sensory neurons. Pretreatment with mYG-II-6 significantly reduced histamine-induced calcium levels and inhibited TRPV1 activity, suggesting its role in blocking the calcium influx channel. Additionally, mYG-II-6 suppressed histamine-induced calcium increase in primary cultures of mouse dorsal root ganglia, indicating its potential antipruritic effect mediated by histamine. Interestingly, mYG-II-6 exhibited inhibitory effects on human MRGPRX2, a G protein-coupled receptor involved in IgE-independent mast cell degranulation. However, it did not inhibit mouse MrgprB2, the ortholog of human MRGPRX2. Molecular docking analysis revealed that mYG-II-6 selectively interacts with the binding pocket of MRGPRX2. Importantly, mYG-II-6 suppressed histamine-induced scratching behaviors in mice.

CONCLUSIONS

Our findings show that mYG-II-6 can alleviate histamine-induced itch sensation through dual mechanisms. This underscores its potential as a versatile treatment for various pruritic conditions.

Phytosphingosine derivatives ameliorate skin inflammation by inhibiting NF-κB and JAK/STAT signaling in keratinocytes and mice

Phytosphingosine is abundant in plants and fungi and is found in mammalian epidermis, including the stratum corneum. Phytosphingosine and its derivatives N-acetyl phytosphingosine and tetraacetyl phytosphingosine are part of the natural defense system of the body. However, these molecules exhibit strong toxicities at high concentrations. We synthesized phytosphingosine derivatives, mYG-II-6 ((Z)-4-oxo-4-(((2S,3S,4R)-1,3,4-trihydroxyoctadecan-2-yl)amino)but-2-enoic acid) and fYG-II-6 ((E)-4-oxo-4-(((2S,3S,4R)-1,3,4-trihydroxyoctadecan-2-yl)amino)but-2-enoic acid), to increase efficacy and decrease toxicity, and the biological activities of the derivatives in the inflammatory response were examined. Both YG-II-6 compounds effectively suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammatory skin damage and inflammatory response in a mouse model. In addition, topical application of fYG-II-6 suppressed ear swelling and psoriasiform dermatitis in the ears of IL-23-injected mice. Anti-inflammatory and antipsoriatic activities of the phytosphingosine derivatives inhibited NF-κB, JAK/signal transducer and activator of transcription (JAK/STAT), and mitogen-activated protein kinase (MAPK) signaling. Finally, the YG-II-6 compounds induced programmed cell death in keratinocytes and mouse skin and were less toxic than phytosphingosine. Our study demonstrated that the phytosphingosine-derived YG-II-6 compounds have much stronger biological potencies than the lead compounds. The YG-II-6 compounds ameliorated inflammatory skin damage. Thus, YG-II-6 compounds are potential topical agents for treating chronic inflammatory skin diseases, such as psoriasis.