Heat stimuli test by infrared reveals rosacea as a heat sensitive skin disorder

A survey-based study suggested sun exposure as possible precipitating factors for rosacea,1Bae Y.I. Yun S.J. Lee J.B. Kim S.J. Won Y.H. Lee S.C. Clinical evaluation of 168 Korean patients with rosacea: the sun exposure correlates with the erythematotelangiectatic subtype.Ann Dermatol. 2009; 21: 243-249Crossref PubMed Scopus (53) Google Scholar but a second study failed to confirm a correlation between rosacea and UV exposure.2McAleer M.A. Fitzpatrick P. Powell F.C. Papulopustular rosacea: prevalence and relationship to photodamage.J Am Acad Dermatol. 2010; 63: 33-39Abstract Full Text Full Text PDF PubMed Scopus (67) Google Scholar Because many facial inflammatory dermatoses are photosensitive or photoaggravated,3Chen L. Zheng J. Does sensitive skin represent a skin condition or manifestations of other disorders?.J Cosmet Dermatol. 2021; 20: 2058-2061Crossref PubMed Scopus (6) Google Scholar we sought to determine whether infrared heat alone could provoke the disease. An InfraCare infrared lamp HP3631 (Philips) was used. Subjects faced the device at a 30-cm distance for 6 minutes. A TiVi700 (WheelsBridge AB) score for local relative red blood cell concentration was determined via polarization spectroscopy, measured in Tivi arbitrary units (TiVi AU).4Guzman-Sanchez D.A. Ishiuji Y. Patel T. Fountain J. Chan Y.H. Yosipovitch G. Enhanced skin blood flow and sensitivity to noxious heat stimuli in papulopustular rosacea.J Am Acad Dermatol. 2007; 57: 800-805Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar VISIA (Canfield Scientific) was used for facial photograph recording. Skin redness assessed by a∗ value (Courage + Khazaka), which represents the red–green value of the skin surface (Supplementary Fig 1, A, available via Mendeley at https://data.mendeley.com/datasets/hss9gb6gr6/2). All features were measured before and after heat stimulation of cheek skin. Patients with erythematotelangiectatic rosacea (ETR, N = 23), papulopustular rosacea (PPR, N = 17), and discoid lupus erythematous (DLE, N = 16) were enrolled, as well as 15 healthy controls. After heat stimulation, the facial temperature of all participants increased from 31.88 to 33.76 °C to an average of 34.93 to 35.31 °C, with no difference among 4 groups (Supplementary Table I, available via Mendeley at https://data.mendeley.com/datasets/hss9gb6gr6/2). All participants experienced visible flushing after heat provocation (Supplementary Fig 1, C to J, available via Mendeley at https://data.mendeley.com/datasets/hss9gb6gr6/2), but the skin of DLE and healthy control subjects did not develop changes in erythema assessment (Supplementary Table I). A significant increase after heat stimulation was observed in both ETR and PPR after heat stimulation for facial TiVi AU (P<.001 for ETR; P <.05 for PPR) and VISIA erythema score (P <.01; P <.001) (Supplementary Table I). Additionally, we found a significant difference in change of TiVi AU between ETR and healthy controls (10.30% ± 9.07% vs 1.84% ± 3.52%, P =.015) (Fig 1). ETR also revealed a higher a∗ after stimulation (P <.001) (Supplementary Table I). To investigate the effects of acute photosensitivity, we next measured minimal erythema dose (MED) for both UV-A and UV-B on abdomen of participants with ETR (N = 20) and PPR (N = 14). Patients with DLE (N = 16) and chronic actinic dermatitis (CAD, N = 25) served as positive controls. The skin types of the patients were type II and III. Overall, 18.75% (3/16) patients with DLE and 52% (13/25) patients with CAD demonstrated a decreased UV-B–MED; 43.75% (7/16) patients with DLE and 96% (24/25) patients with CAD had decreased UV-A–MED. In contrast, only 5% (1/20) of patients with ETR showed a decreased MED for UV-B (P <.001) and 10% (2/20) for UV-A (P <.0001). PPR demonstrated similar results (Table I). Although subjects in ETR and PPR groups had lighter skin, they showed a significantly higher MED than patients with DLE and CAD (Supplementary Fig 2, available via Mendeley at https://data.mendeley.com/datasets/hss9gb6gr6/2). This suggests that photoaggravation of rosacea may not come from UV.Table IThe difference of MED–UV-B and MED–UV-A in ETR, PPR, DLE, and CADDiseaseSkin phototype (type II/III, N)Male/female (N)Age (y)Decreased MED–UV-BN (%)Decreased MED–UV-AN (%)ETR14/60/2039.251 (5.00)2 (10.00)PPR10/40/1438.431 (7.14)1 (7.14)DLE8/80/1636.93 (18.75)7 (43.75)CAD0/2520/559.9313 (52.00)24 (96.00)P <.001P <.0001Decreased UV-B–MED considered as ≤23.4 mJ/cm2; decreased UVA-MED considered as ≤24 J/m2; significantly different frequencies among the 4 groups were detected by χ2 test.CAD, Chronic actinic dermatitis; DLE, discoid lupus erythematous; ETR, erythematotelangiectatic rosacea; MED, minimal erythema dose; N, number of subjects; PPR, papulopustular rosacea; UV-B, ultraviolet B; UV-A, ultraviolet A. Open table in a new tab Decreased UV-B–MED considered as ≤23.4 mJ/cm2; decreased UVA-MED considered as ≤24 J/m2; significantly different frequencies among the 4 groups were detected by χ2 test. CAD, Chronic actinic dermatitis; DLE, discoid lupus erythematous; ETR, erythematotelangiectatic rosacea; MED, minimal erythema dose; N, number of subjects; PPR, papulopustular rosacea; UV-B, ultraviolet B; UV-A, ultraviolet A. Guzman-Sanchez et al4Guzman-Sanchez D.A. Ishiuji Y. Patel T. Fountain J. Chan Y.H. Yosipovitch G. Enhanced skin blood flow and sensitivity to noxious heat stimuli in papulopustular rosacea.J Am Acad Dermatol. 2007; 57: 800-805Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar reported enhanced sensitivity to heat stimuli in rosacea. Of interest, alpha receptor agonists and a 26S proteasome inhibitor inhibit erythema in rosacea,5Jackson J.M. Coulon R. Arbiser J.L. Evaluation of a first-in-class proteasome inhibitor in patients with moderate to severe rosacea.J Drugs Dermatol. 2021; 20: 660-664PubMed Google Scholar which could be the possible mechanism underlying the heat-induced inflammation in rosacea. Our study lends additional support for a provocative role of infrared heat stimuli in rosacea. Physical sunlight protection that blocks both UV exposure and heat may be preferable. None.