Timing of itch among children with atopic dermatitis

Circadian Rhythms in Skin Barrier Function in Atopic Dermatitis: A Pilot Study

Atopic dermatitis (AD) is symptomatically worse in the evening, but the mechanism driving nocturnal eczema remains elusive. Our objective was to determine the circadian rhythm of skin barrier function measured by transepidermal water loss (TEWL) in AD patients and explore the molecular underpinnings. A pilot study was performed on a diverse group of AD (n = 4) and control (n = 2) young patients. We used an inpatient tightly controlled, modified, constant routine protocol. TEWL was measured at least every 90 min in the antecubital fossa (lesional) and forearm, while whole blood samples were collected every 4 h. Results show a significant difference in the antecubital fossa TEWL in the AD group versus controls. TEWL in control skin decreases starting a few hours prior to bedtime, both in the antecubital fossa and in the forearm, while in the AD forearm skin, pre-bedtime TEWL increases. We identified 1576 differentially expressed genes using a time-dependent model. The top 20 upregulated gene ontology pathways included neuronal pathways, while the downregulated functional terms included innate immune signaling and viral response. Similar pathways positively correlated with forearm TEWL in controls and inversely with the AD group. Upregulation in sensory perception pathways correlated with increases in lesional (antecubital fossa) TEWL in the evening. Results show skin barrier function worsens in the evening in the AD group, at a time when barrier is normally rejuvenating in healthy skin. This timing and the detection of transcriptomic signatures of sensory perception and diminished viral response might correspond to the nocturnal itch. Larger studies are needed to evaluate these associations in the skin.

Circadian rhythm of cutaneous pruritus

One of the most common and significant symptoms for skin disorders is pruritus. Additionally, it serves as a significant catalyst for the exacerbation or reoccurrence of skin diseases. Pruritus seriously affects patients' physical and mental health, and even the quality of life. It brings a heavy burden to the patients, the families, even the whole society. The pathogenesis and regulation mechanisms for pruritus are complicated and have not yet been elucidated. Previous clinical studies have shown that itch worsens at night in scabies, chronic pruritus, atopic dermatitis, and psoriasis, suggesting that skin pruritus may change with circadian rhythm. Cortisol, melatonin, core temperature, cytokines, and prostaglandins are the main regulatory factors of the circadian rhythm of pruritus. Recent studies have shown that some CLOCK genes, such as BMAL1, CLOCK, PER, and CRY, play an important role in the regulation of the circadian rhythm of pruritus by regulating the Janus tyrosine kinase (JAK)-signal transducer and activator of transcription (STAT) and nuclear factor kappa-B (NF-κB) signaling pathways. However, the mechanisms for circadian clock genes in regulation of circadian rhythm of pruritus have not been fully elucidated. Further studies on the mechanism of circadian clock genes in the regulation of circadian rhythm of pruritus will lay a foundation for elucidating the regulatory mechanisms for pruritus, and also provide new ideas for the control of pruritus and the alleviation of skin diseases.

Assessment and Management of Sleep Disturbances in Atopic Dermatitis: A Review

Atopic dermatitis (AD) is a chronic burdensome inflammatory skin disease with well-established cutaneous and systemic comorbidities and disease burden. AD particularly has profound impacts on sleep in individuals of all ages. Sleep disturbances (SDs) affect 6.2% of school-age children and 33-87.1% of adults with AD. This narrative review addresses the burden of SD in AD patients, as well as biological mechanisms of SD in AD, including biological clocks influencing sleep, inflammation, and behavior. Approaches for early detection, diagnosis, objective quantification, patient education, and management are reviewed. It is imperative to break the itch-scratch cycle to reduce SDs and improve quality of life in individuals with AD.

Physical influences on the skin barrier and pathogenesis of allergy

PURPOSE OF REVIEW

As the incidence of allergic conditions has increased in recent decades, the effects of climate change have been implicated. There is also increased knowledge on the effects of other physical influences, such as scratching and Staphylococcus aureus . The skin barrier is the first line of defense to the external environment, so understanding the ways that these factors influence skin barrier dysfunction is important.

RECENT FINDINGS

Although the impact on environmental exposures has been well studied in asthma and other allergic disorders, there is now more literature on the effects of temperature, air pollution, and detergents on the skin barrier. Factors that cause skin barrier dysfunction include extreme temperatures, air pollution (including greenhouse gases and particulate matter), wildfire smoke, pollen, scratching, S. aureus, and detergents.

SUMMARY

Understanding the ways that external insults affect the skin barrier is important to further understand the mechanisms in order to inform the medical community on treatment and prevention measures for atopic conditions.

Timing of scratch and limb movements during sleep in children with atopic dermatitis

In this retrospective analysis of children with atopic dermatitis (n = 6) who coincidentally had a video polysomnography, we found that most nocturnal limb movements in children with atopic dermatitis are non-scratch versus scratch, 109.0 ± 67.9 vs. 15.3 ± 5.4 (p = 0.01). Average scratch duration was 8.4 ± 2.7 s, which was not different by sleep stage. Scratch movements are distinct in timing, occurring most often during N2 sleep, in the first third of sleep, and peaking at 90 minutes after sleep onset, corresponding with completion of the first sleep cycle.