Psoriasis is a chronic inflammatory skin disease characterized by epidermal gene abnormalities, epidermal barrier defects and inflammation. Corticosteroids are considered to be standard treatments, but often come with side effects and lose efficacy with long-term use. Alternative treatments targeting the epidermal barrier defect are needed to manage the disease. Film-forming substances such as xyloglucan, pea protein and Opuntia ficus-indica extract (XPO) have generated interest for their ability to restore skin barrier integrity and may pose an alternative approach to disease management. Thus, the aim of this two-part study was to evaluate the barrier-protective properties of a topical cream containing XPO on the membrane permeability of keratinocytes exposed to inflammatory conditions and compare its efficacy to dexamethasone (DXM) in an in vivo model of psoriasis-like dermatitis. XPO treatment significantly reduced S. aureus adhesion, subsequent skin invasion and restored epithelial barrier function in keratinocytes. Furthermore, the treatment restored the integrity of keratinocytes, reducing tissue damage. In mice with psoriasis-like dermatitis, XPO significantly reduced erythema, inflammatory markers and epidermal thickening with a superior efficacy to dexamethasone. Given the promising results, XPO may represent a novel steroid-sparing therapeutic for epidermal-related diseases such as psoriasis, thanks to its ability to preserve skin barrier function and integrity.

Psoriasis is strongly associated with insulin resistance (IR). Lipid profile disturbances and upregulation of enzymes crucial for fatty acid oxidation have been reported in patients with psoriasis. Mitochondrial ß-oxidation is altered in patients with IR. Common mitochondrial dysfunction may be involved in the origin of both diseases.

This study aimed to evaluate mitochondrial ß-oxidation, intermediary metabolism, and mitochondrial content in psoriatic patients with or without IR and compare them to healthy controls.

The participants were divided into three groups: (1) psoriasis and IR (n = 26); (2) psoriasis without IR (n = 17); and (3) healthy controls (n = 17). Quantification of amino acids and acylcarnitines (AC) by tandem mass spectrometry, determination of urinary organic acids by gas chromatography/mass spectrometry (GC/MS), and mitochondrial DNA quantification were performed in all groups.

When comparisons were made between the two psoriatic groups, no differences were found between: C5DC + C6OH, C16:1, Met/Leu, Met/Phe, C16:1/C16, and C5DC + C6OH/C4DC + C5OH ratios. Nine analytes were different: phenylalanine, Cit/Phe, and Cit/Tyr ratios, C0, C3, C5, C6DC, C16, and C18:1OH. There were no correlations between psoriasis area and severity index (PASI), body mass index (BMI) and duration of disease with ACs. A higher proportion of patients with psoriasis showed increased urine levels of uric acid and hippuric acid (p = 0.01). The mtDNA content was significantly higher in cases than in controls, with no differences between IR and non-IR psoriatic patients.

Psoriasis patients with and without IR have a different acylcarnitine profile reflecting impaired ß-oxidation. A distinctive profile of acylcarnitines suggests an involvement of mitochondrial function associated with an increase in stearoyl CoA desaturase (SCD) activity in psoriatic patients with and without IR.