A multicentre, randomized, double-masked, parallel group, vehicle-controlled phase IIb study to evaluate the safety and efficacy of 1% and 3% topical minocycline gel in patients with papulopustular rosacea.

BACKGROUND: Papulopustular rosacea is characterized by chronic facial erythema and inflammatory facial lesions. Minocycline has anti-inflammatory properties which may be effective in the treatment of rosacea inflammatory lesions. OBJECTIVES: To assess the safety and efficacy of once-daily topical minocycline gel 1% and 3% in patients with papulopustular rosacea. METHODS: This was a prospective, 12-week, double-blinded study conducted at 26 sites in the United States; 270 patients with papulopustular rosacea and 12-40 inflammatory lesions were randomized to minocycline 1%, minocycline 3% or vehicle. The primary endpoint was the mean change in inflammatory lesions at week 12. Key secondary endpoints included success on an Investigator's Global Assessment (IGA). RESULTS: Baseline mean lesion counts were 24·6, 25·1 and 24·3 in the minocycline 1%, minocycline 3% and vehicle groups, respectively; at week 12, the counts had decreased by 12·6, 13·1 and 7·9, respectively. Minocycline significantly decreased lesions, compared with the vehicle [P = 0·01, 95% confidence interval (CI) 7·9 to 0·9, for minocycline 1%; P = 0·007, 95% CI 8·3 to 1·3, for minocycline 3%]. The proportion of patients achieving IGA success was 39% in the minocycline 1% arm [P = 0·34, odds ratio (OR) 1·396 and OR 95% CI 0·71 to 2·75 vs. vehicle], 46% in the minocycline 3% arm (P = 0·04, OR 2·03 and OR 95% CI 1·04 to 3·95 vs. vehicle) and 31% in the vehicle arm. CONCLUSIONS: Minocycline topical gel appears to be safe and tolerable at concentrations of 1% and 3%, and both concentrations significantly decreased inflammatory lesion counts, with a significantly larger proportion of patients achieving IGA success at week 12 in the minocycline 3% arm. These findings support further evaluation of minocycline gel for treating inflammatory lesions associated with papulopustular rosacea. Linked Comment: Hampton. Br J Dermatol 2020; 183:412-413.

Aquaporin 0-calmodulin interaction and the effect of aquaporin 0 phosphorylation.

Aquaporin 0 (AQP0), also known as major intrinsic protein of lens, is the most abundant membrane protein in the lens and it undergoes a host of C-terminally directed posttranslational modifications. The C-terminal region containing the major phosphorylation sites is a putative calmodulin-binding site, and calmodulin has been shown to regulate AQP0 water permeability. The purpose of the present study was to elucidate the role of AQP0 phosphorylation on calmodulin binding. AQP0 C-terminal peptides were synthesized with and without serine phosphorylation on S231 and S235, and the ability of these peptides to bind dansyl-labeled calmodulin and the calcium dependence of the interaction was assessed using a fluorescence binding assay. The AQP0 C-terminal phosphorylated peptides were found to have 20-50-fold lower affinities for calmodulin than the unphosphorylated peptide. Chemical cross-linking studies revealed specific sites of AQP0-calmodulin interaction that are significantly reduced by AQP0 phosphorylation. These data suggest that AQP0 C-terminal phosphorylation affects calmodulin binding in vivo and has a role in regulation of AQP0 function.