Skin transient receptor potential channels expression and microvascular reactivity to cooling in primary and secondary Raynaud's phenomenon.

Temperature-sensitive Transient Receptor Potential (TRP) channels contribute to modulating skin vascular tone. Their role in Raynaud's Phenomenon (RP) remains unknown. We aimed to investigate TRPs expression in the skin, along with microvascular reactivity to cooling in patients with primary and secondary RP, compared with healthy subjects. Skin blood flow was measured in 10 regions of interest on the dorsum of the hand before, during, and after a 30-min cooling at 8°C. Skin biopsies were performed from a subset of participants at the distal phalanx before and after cooling. RNAs were extracted, sequenced, and TRPs mRNA expression quantified. TRPs mRNA were successfully quantified, but no significant differences in their expression were observed between groups, or in response to cooling. There was a decreased perfusion at the distal phalanx over time, in secondary RP compared with primary RP (adjusted p = 0.03) or healthy subjects (adjusted p = 0.042). Gene expression profiles were more similar between primary RP and healthy subjects than with secondary RP. This study shows an impairment of microvascular reactivity to cold in secondary, but not in primary RP. Transcriptomic data suggest involvement of the NO pathway in secondary RP, while TRP channel expression appears unchanged; however, their function could be impaired, which should be further investigated.