Clinical and pathological findings of chronic actinic dermatitis

Successful Treatment of Chronic Actinic Dermatitis with Tofacitinib

We present the case of a 58-year-old male patient who presented with pruritic skin plaques and papules on the scalp, face, back, and back of the hands for over a year. The symptoms worsened upon exposure to sunlight and improved on cloudy days. Despite previous attempts at treatment with glucocorticoid ointment and antihistamine drugs, the patient experienced progressive aggravation of symptoms. Physical examination revealed hypertrophic and infiltrating nodules, with significant scratches and local exudation. Skin biopsy confirmed the diagnosis of sun-induced dermatosis. The patient was initiated on tofacitinib, an oral Janus Kinase inhibitor, along with a halometasone ointment, oral ebastine tablets, and strict sun protection. Over the course of four revisits spanning four months, the patient experienced a significant improvement in symptoms, with the rash almost disappearing and pruritus subsiding. The treatment was well tolerated and no adverse effects were observed. Follow-up for six months post-treatment showed no recurrence of symptoms. This case highlights the efficacy of tofacitinib in managing sun-induced pruritic plaques and suggests it as a potential therapeutic option in similar cases.

Deficiency of N6-Methyladenosine Demethylase ALKBH5 Alleviates Ultraviolet B Radiation-Induced Chronic Actinic Dermatitis via Regulating Pyroptosis

Pyroptosis is an inflammatory programmed cell death (PCD) and is reported to be associated with N6-methyladenosine (m6A) modification. This study aimed to investigate the mechanism of m6A demethylase AlkB homolog 5 (ALKBH5) in pyroptosis in the process of chronic actinic dermatitis (CAD). Changes of m6A-related genes were evaluated between CAD and normal samples using quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Human keratinocytes (HaCaT cells) exposed to ultraviolet B (UVB; 10, 20, and 30 mJ/cm2), followed by evaluation of cell proliferation, cell apoptosis, inflammatory cytokines (interleukin (IL)-1β, IL-18, and tumor necrosis factor (TNF-α)), and pyroptosis-related proteins (gasdermin D (GSDMD), Caspase-1, and Caspase-4). Small interfering RNA (siRNA) targeting ALKBH5 was transfected into HaCaT cells to assess the effect of si-ALKBH5 on CAD. A CAD mice model was induced after exposure to UVB (250 mJ/cm2 per day) to confirm the role of ALKBH5 in CAD. AKKBH5 was highly expressed in CAD patients. UVB also promoted ALKBH5 expression, increased cell apoptosis, and induced the release of inflammatory cytokines (IL-1β, IL-18, and TNF-α) as well as pyroptosis-related proteins (GSDMD, Caspase-1, and Caspase-4). Silencing ALKBH5 repressed cell apoptosis and suppressed UVB-induced pyroptosis and inflammatory response. Meanwhile, silencing ALKBH5 attenuated UVB-induced skin damage of CAD mice, accompanied with the reduction in expression of inflammatory cytokines and pyroptosis-related proteins. This study helps to further understand the mechanism of ALKBH5 in CAD-induced pyroptosis and provides novel ideas for the research and management of CAD.

Role of interleukin-36γ induced by ultraviolet radiation in chronic actinic dermatitis

BACKGROUND

Chronic actinic dermatitis (CAD) is an immune-mediated photodermatosis characterized by a high eosinophil count and total immunoglobulin E (IgE) in the peripheral blood of patients. At present, however, the reasons for their elevation remain unclear.

OBJECTIVE

The current study aimed to detect changes in inflammatory cytokines in CAD and explore their role in this disease.

METHODS

Enzyme-linked immunosorbent assay and Luminex assay were conducted to measure inflammatory factor levels. Immunohistochemical analysis and quantitative real-time polymerase chain reaction were performed to evaluate the expression levels of interleukin-36γ (IL-36γ), IL-8, chemokine (C-C motif) ligand 17 (CCL17), and CCL18. CCK8 kits were used to assess cell proliferation. Immunofluorescence was used to detect nuclear factor κB (NF-κB) p65 nuclear translocation. Western blot analysis was performed to detect the protein expression level of phosphorylated NF-κB (p-NF-κB) p65. Hematoxylin and eosin and Masson trichrome staining were applied to observe histological changes in a chronic photo-damaged mouse model.

RESULTS

Eosinophils, total IgE, IL-36γ, IL-8, tumor necrosis factor α, CCL17, and CCL18 were elevated in CAD. Of note, IL-36γ promoted the proliferation of eosinophilic cells (EOL-1) and the production of IgE in peripheral blood mononuclear cells. IL-36γ also promoted the production of IL-8 and CCL18 in immortalized human keratinocytes (HaCaT cells), while ultraviolet radiation (UVR)-induced IL-36γ via activation of the NF-κB signaling pathway.

CONCLUSIONS

IL-36γ was involved in the pathogenesis of CAD and UVR contributed to the production of IL-36γ, which may provide a novel therapeutic target for CAD.

LncRNA-WAKMAR2 regulates expression of CLDN1 to affect skin barrier through recruiting c-Fos

BACKGROUND

Chronic actinic dermatitis (CAD) is an immune-mediated photo-allergic skin disease. In the clinic, the treatment of this disease is hampered by the lack of proper understanding of the skin barrier dysfunction mechanism.

OBJECTIVE

To illuminate the mechanism of skin barrier dysfunction in CAD.

METHODS

Transcriptome sequencing and protein profiling were used to detect skin barrier injury-related genes. RNA pull down, a promoter-reporter gene assay, and chromatin isolation by RNA purification-sequencing were used to elucidate the effect of WAKMAR2 in skin barrier functionality.

RESULTS

Transcriptome sequencing from patient's tissues showed a significantly decreased expression of WAKMAR2. Down-regulation of WAKMAR2 destroyed the keratinocyte barrier. Moreover, WAKMAR2 can directly bind to the c-Fos protein. This novel long non-coding RNA (LncRNA)-protein complexes were targeted to the CLDN1 promotor. Overexpression of WAKMAR2 enhanced the promoter activity of CLDN1, while the addition of AP-1 inhibitor could reverse this phenomenon. Furthermore, our in vivo results suggested that expression of WAKMAR2 was required for the repair of skin damage in mice induced by ultraviolet irradiation.

CONCLUSIONS

We identified a crucial LncRNA (WAKMAR2) for the protection of the skin barrier in vitro and in vivo. Mechanically, it can specifically interact with c-Fos protein for the regulation of CLDN1, a finding which could be applied for CAD treatment.

Curcumin Improves Keratinocyte Proliferation, Inflammation, and Oxidative Stress through Mediating the SPAG5/FOXM1 Axis in an In Vitro Model of Actinic Dermatitis by Ultraviolet

Background

Chronic actinic dermatitis (CAD) is an abnormally proliferating photoallergic skin disease. Dysregulated inflammation and oxidative stress are the immediate factors in the abnormal proliferation of keratinocytes. This study aimed to investigate the effect of curcumin on the aberrant proliferation of keratinocytes in an in vitro (actinic dermatitis) AD model and the possible molecular mechanisms.

Methods

The keratinocytes were irradiated with ultraviolet (UV) to construct an in vitro AD model and then processed with different concentrations of curcumin. Cell viability, oxidative stress markers (SOD, GSH-PX, and MDA), activated oxygen species (ROS), and inflammation markers (IL-1β, IL-6, IL-18, and TNFα) were determined, respectively. Western blot was applied to assay the profiles of apoptosis-related proteins (Bax, Bcl-xL, Caspase3, Caspase8, and Caspase9), oxidative stress proteins (Keap1, Nrf2, HO-1, COX2, and iNOS), and inflammatory proteins (NF-κB, MMP1, and MMP9) and SPAG5/FOXM1. Functionally, SPAG5 or FOXM1 overexpression and knockdown models were constructed in keratinocytes to characterize their influence on UV irradiation-mediated keratinocyte dysfunction.

Results

Curcumin weakened UV-mediated inflammation, proliferation, and oxidative stress and impaired apoptosis in keratinocytes. UV boosted SPAG5/FOXM1 expression in cells, while curcumin concentration-dependently retarded SPAG5/FOXM1 expression. Overexpression of SPAG5/FOXM1 fostered UV-mediated inflammation, proliferation, oxidative stress, and intensified apoptosis, whereas curcumin mostly reversed the SPAG5/FOXM1-mediated effects. In addition, knocking down SPAG5/FOXM1 ameliorated UV-mediated keratinocyte dysfunction, whereas curcumin failed to exert further protective effects in cells with knockdown of SPAG5/FOXM1.

Conclusion

Curcumin modulated proliferation, inflammation, oxidative stress, and apoptosis of keratinocytes by restraining the SPAG5/FOXM1 axis.