The ability of biomarkers to assess the severity of atopic dermatitis

Background

To develop precision medicine for atopic dermatitis (AD), it is critical to establish relevant biomarkers. However, the characteristics of various biomarkers have not been fully understood. We previously carried out the Biomarkers to Predict Clinical Improvement of AD in Patients Treated with Dupilumab (B-PAD) study, a comprehensive nationwide study in Japan, to explore biomarkers for AD.

Objective

The aim of this study is to find biomarkers associated with objective and subjective clinical findings in patients with moderate-to-severe AD based on the B-PAD study and to identify biomarkers sensitive enough to assess the severity of AD.

Methods

We performed the B-PAD study as a consortium composed of 19 medical facilities in Japan, enrolling 110 patients with moderate-to-severe AD. We evaluated the Eczema Area and Severity Index (EASI) for objective assessment as well as the Patient-Oriented Eczema Measure (POEM) and a numeric rating scale for pruritus (pruritis-NRS) for subjective assessment, measuring 19 biomarkers at baseline.

Results

We found that 12, 6, and 7 biomarkers showed significant and positive associations with the EASI, POEM, and pruritis-NRS, respectively. Most of the biomarkers associated with either the POEM or the pruritis-NRS were included among the biomarkers associated with EASI. Of the biomarkers examined, CCL26/eotaxin-3 and SCCA2 were the most capable of assessing severity for EASI, as shown by the 2 kinds of receiver operating characteristic analyses, respectively, whereas lactate dehydrogenase was the best for both the POEM and pruritis-NRS, again using the 2 analyses.

Conclusion

We found biomarkers associated with the EASI, POEM, and pruritis-NRS, respectively, based on the B-PAD study. Moreover, we identified CCL26/eotaxin-3 and/or SCCA2 as the biomarkers having the greatest ability to assess severity in the EASI; lactate dehydrogenase did the same for the POEM and pruritis-NRS. These findings will be useful in treating patients with moderate-to-severe AD.

[RECOMMENDATION FOR ITCH ASSESSMENT FROM THE ATOPIC ITCH CONSENSUS MEETING (AICOM)]

BACKGROUND

Itch is the most troublesome symptom of atopic dermatitis, and it is important to assess it appropriately for optimal treatment. We discussed issues regarding itch and the most appropriate methods of assessment at the Atopic Itch Consensus Meeting (AICOM), attended by physicians and researchers with expertise in itch treatment and research.

METHODS

The AICOM participants prepared a draft consensus statement that addressed the most appropriate itch assessment methods for age groups <2 years, 2-6 years, 7-14 years, and ≥15 years. Consensus was defined as agreement by ≥80% of the participants.

RESULTS

Votes were cast by 20 participants (8 dermatologists, 7 pediatricians, and 5 researchers), and a consensus on the best current methods of itch assessment was reached with 95% agreement. For infants and preschool children, because subjective evaluation is difficult, a checklist for itch assessment was developed for caregivers.

CONCLUSION

For itch assessment, we recommend subjective evaluation by the patient using a rating scale. For infants and preschoolers, evaluation should be done by the caregiver using a checklist, combined with objective evaluation (of skin lesions, for example) by a physician. We anticipate that more objective itch assessment indices will be established in the future.

Oncostatin M suppresses IL31RA expression in dorsal root ganglia and interleukin-31-induced itching

Background

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by intermittent itchy rash. Type 2 inflammatory cytokines such as interleukin (IL)-4, IL-13, and IL-31 are strongly implicated in AD pathogenesis. Stimulation of IL-31 cognate receptors on C-fiber nerve endings is believed to activate neurons in the dorsal root ganglion (DRG), causing itch. The IL-31 receptor is a heterodimer of OSMRβ and IL31RA subunits, and OSMRβ can also bind oncostatin M (OSM), a pro-inflammatory cytokine released by monocytes/macrophages, dendritic cells, and T lymphocytes. Further, OSM expression is enhanced in the skin lesions of AD and psoriasis vulgaris patients.

Objective

The current study aimed to examine the contributions of OSM to AD pathogenesis and symptom expression.

Methods

The expression levels of the OSM gene (OSM) and various cytokine receptor genes were measured in human patient skin samples, isolated human monocytes, mouse skin samples, and mouse DRG by RT-qPCR. Itching responses to various pruritogens were measured in mice by counting scratching episodes.

Results

We confirmed overexpression of OSM in skin lesions of patients with AD and psoriasis vulgaris. Monocytes isolated from the blood of healthy subjects overexpressed OSM upon stimulation with IL-4 or GM-CSF. Systemic administration of OSM suppressed IL31RA expression in the mouse DRG and IL-31-stimulated scratching behavior. In contrast, systemic administration of OSM increased the expression of IL-4- and IL-13-related receptors in the DRG.

Conclusion

These results suggest that OSM is an important cytokine in the regulation of skin monocytes, promoting the actions of IL-4 and IL-13 in the DRG and suppressing the action of IL-31. It is speculated that OSM released from monocytes in skin modulates the sensitivity of DRG neurons to type 2 inflammatory cytokines and thereby the severity of AD-associated skin itch.

Monitoring Sleep and Scratch Improves Quality of Life in Patients with Atopic Dermatitis

Atopic dermatitis itch may cause sleep disturbance and impair quality of life. For patients finding topical therapy difficult to continue, it is important to control itch and reduce scratching. This study developed algorithms to measure nocturnal sleep and scratch, using an actigraph device worn on the back of the hand, and assessed smartphone application feedback to improve adherence with therapy. In the first trial, actigraph measurements in 5 participants who wore the device were highly correlated with measurements by a sleep-monitoring device beneath the mattress. Total actigraph-measured scratching duration for each hour of sleep was highly correlated with measurements by a person rating infrared video-recording of the sleepers. In the second trial, 40 patients with atopic dermatitis were randomly allocated into an intervention group that used the actigraph and smartphone application, and a control group that did not. Both groups were instructed to use the same moisturizer. Dermatology Life Quality Index scores decreased significantly from baseline and were lower than those in the control group at week 8. It is suggested that the device and associated smartphone application reinforced therapy adherence, moisturizer use, and contributed to improved quality of life in patients with atopic dermatitis.

[JAPANESE TRANSLATION AND LINGUISTIC VALIDATION OF THE RECAP OF ATOPIC ECZEMA (RECAP)]

BACKGROUND

The Recap of atopic eczema (RECAP), a new core outcome of the atopic dermatitis trial, was translated into Japanese and linguistically validated.

METHODS

Translation into Japanese was accomplished according to the ISPOR (International Society for Pharmacoeconomics and Outcome Research) guidelines and the basic guidelines for scale translation. The translation process included two forward translations, reconciliation with native English speakers, third-party back translation, cognitive debriefing, review and harmonization by the original authors. Twenty-seven atopic dermatitis and pediatric specialists from 21 centers in Japan participated in the translation process. Cognitive debriefing was conducted through face-to-face interviews using a think-aloud method with the interview guide including questions about comprehensibility, relevance, comprehensiveness, recall period and suggested improvements, based on the COSMIN methodology.

RESULTS

No linguistic or cultural problems were encountered in the translation into Japanese. Cognitive debriefings were conducted with 10 adult patients and 10 parents of pediatric patients. Some minor modifications were made following discussion and approval by the research team and the original authors. The Japanese version of RECAP was considered to be understandable, comprehensive and relevant for adult patients and families of pediatric patients.

CONCLUSION

The Japanese version of the RECAP, which has been validated as linguistically equivalent to the original version, is now available. Further evaluation of the measurement properties is needed in the future.

Role of Eosinophil Relative Count and Neutrophil-to-Lymphocyte Ratio in the Assessment of Severity of Atopic Dermatitis

The aim of this study is to elucidate the relationship between 2 different types of severity-indicating parameters (i.e. between subjective and objective severity-indicating parameters in patients with atopic dermatitis. The disease severity of 55 patients with atopic dermatitis was assessed using 7 subjective parameters indicating severity, including visual analogue scale for itch, Patient-Oriented Eczema Measure, 5-D itch scale, Dermatology Life Quality Index, Eczema Area and Severity Index, body surface area, and Investigator Global Assessment, and 8 objective parameters indicating severity, including eosinophil relative count, neutrophil-to-lymphocyte ratio, lactate dehydrogenase, and thymus and activation-regulated chemokine. Five subjective parameters reflecting itch correlated significantly with eosinophil relative count, but not with neutrophil-to-lymphocyte ratio. In contrast, 2 subjective parameters, mainly reflecting the degree of inflammation and area of affected regions, correlated significantly with neutrophil-to-lymphocyte ratio. The eosinophil relative count may correlate with the degree of itch, while the neutrophil-to-lymphocyte ratio may correlate with the degree of inflammation and the area of the affected region. The eosinophil relative count and neutrophil-to-lymphocyte ratio may thus be stand-alone parameters from each other in the assessment of the severity of atopic dermatitis.

The first Japanese family of CDH3-related hypotrichosis with juvenile macular dystrophy

BACKGROUND

Hypotrichosis with juvenile macular dystrophy (HJMD) is a rare autosomal recessive inherited disorder caused by biallelic variants in the CDH3 gene encoding P-cadherin. Here, we report two Japanese sibling patients with HJMD.

METHODS

Whole-exome sequencing (WES) was performed to identify disease-causing variants. In addition, ophthalmic and dermatological examinations were performed to classify the phenotype of each patient.

RESULTS

The WES analysis revealed novel compound heterozygous CDH3 variants [c.123_129dupAGGCGCG (p.Glu44fsX26) and c.2280+1G>T] in both patients; the unaffected, nonconsanguineous parents each exhibited one of the variants. Both patients showed the same clinical findings. Ophthalmologically, they exhibited progressive loss of visual acuity and chorioretinal macular atrophy, as examined with fundoscopy, fundus autofluorescence imaging, and optical coherence tomography. Full-field electroretinography, assessing generalized retinal function, revealed nearly normal amplitudes of both rod- and cone-mediated responses. Multifocal electroretinography, reflecting macular function, showed extremely decreased responses in the central area, corresponding to the chorioretinal atrophy. Dermatological examination revealed diffuse thinning of the scalp hair, which was sparse and fragile.

CONCLUSION

This is the first report of Japanese patients with HJMD and novel compound heterozygous truncating variants in CDH3. Our findings can expand the knowledge and understanding of CDH3-related HJMD, which could be helpful to ophthalmologists and dermatologists.

Direct evidence that the brain reward system is involved in the control of scratching behaviors induced by acute and chronic itch

In the present study, we demonstrated that there is a direct relationship between scratching behaviors induced by itch and functional changes in the brain reward system. Using a conditional place preference test, the rewarding effect was clearly evoked by scratching under both acute and chronic itch stimuli. The induction of ΔFosB, a member of the Fos family of transcription factors, was observed in dopamine transporter (DAT)-positive dopamine neurons in the ventral tegmental area (VTA) of mice suffering from a chronic itch sensation. Based on a cellular analysis of scratching-activated neurons, these neurons highly expressed tyrosine hydroxylase (TH) and DAT genes in the VTA. Furthermore, in an in vivo microdialysis study, the levels of extracellular dopamine in the nucleus accumbens (NAcc) were significantly increased by transient scratching behaviors. To specifically suppress the mesolimbic dopaminergic pathway using pharmacogenetics, we used the TH-cre/hM4Di mice. Pharmacogenetic suppression of mesolimbic dopaminergic neurons significantly decreased scratching behaviors. Under the itch condition with scratching behaviors restricted by an Elizabethan collar, the induction of ΔFosB was found mostly in corticotropin-releasing hormone (CRH)-containing neurons of the hypothalamic paraventricular nucleus (PVN). These findings suggest that repetitive abnormal scratching behaviors under acute and chronic itch stimuli may activate mesolimbic dopamine neurons along with pleasant emotions, while the restriction of such scratching behaviors may initially induce the activation of PVN-CRH neurons associated with stress.

Exploration of biomarkers to predict clinical improvement of atopic dermatitis in patients treated with dupilumab: A study protocol

BACKGROUND

Atopic dermatitis (AD) is a common eczematous skin disorder that profoundly reduces the quality of life due to intractable pruritus. Excellent therapeutic success of the anti-interleukin 4 receptor-α antibody dupilumab in clinical trials and a real-world clinical context indicates the crucial roles of interleukin (IL)-4 and IL-13 in the pathogenesis of AD. Along with the clinical improvement in skin scores and pruritus, dupilumab significantly and progressively reduces and normalizes the upregulated expression of T helper type 2 signatures such as Chemokine (C-C motif) ligand (CCL)17, CCL18, CCL22, and CCL26 in the lesional skin of AD. However, no blood/serum biomarkers are known to predict good or poor outcome in patients with AD treated with dupilumab.

METHODS

Patients are at least 18 years of age and have moderate-to-severe AD with Eczema Area and Severity Index (EASI) ≥16, Investigator's Global Assessment ≥3, and body surface area ≥10%. We are going to enroll more than 130 subjects from 18 medical facilities. Clinical objective findings will be evaluated by EASI. Subjective symptoms will be assessed by Patient-Oriented Eczema Measure, Numerical Rating Scale for Pruritus (Pruritus-NRS), Skin Comfort-NRS, and Treatment Satisfaction-NRS. We will measure 18 blood/serum biomarkers including % eosinophils in blood cell count, lactate dehydrogenase, total IgE, soluble interleukin 2 receptor, CCL17, CCL18, CCL22, CCL26, CCL27, IL-13, IL-22, IL-24, IL-25, IL-31, IL-33, thymic stromal lymphopoietin, periostin, and squamous cell carcinoma antigen-2. The clinical evaluation and biomarker sampling will be performed at 0, 2, 4, 8, and 16 weeks of dupilumab treatment. We will also perform proteomic analysis (of roughly 300 proteins) of the patients' sera obtained at 0 and 2 weeks of treatment. The primary endpoint is the association between "baseline levels of 18 biomarkers" and "% change from baseline of EASI at 16 weeks of dupilumab treatment."

DISCUSSION

This is the first clinical trial to explore the biomarkers, including potential proteomic markers, most strongly associated with improvement in EASI in patients with moderate-to-severe AD treated with dupilumab for 16 weeks (B-PAD study). A limitation is that we will only enroll Japanese patients.

Chronic intestinal pseudo-obstruction with pneumatosis cystoides intestinalis in a patient with systemic sclerosis: A case report

RATIONALE

Chronic intestinal pseudo-obstruction (CIPO) and pneumatosis cystoides intestinalis (PCI) are rare abdominal diseases and the pathological mechanisms have not been fully elucidated. Systemic sclerosis (SSc), which is characterized by the progressive sclerotic changes of skin and internal organs, is a refractory collagen disease and is frequently associated with digestive disorders including CIPO.

PATIENT CONCERNS

A 68-year-old woman who has been well managed for SSc over the long term, who presented with abdominal fullness for the first time.

DIAGNOSES

Abdominal X-ray and computed tomography (CT) images showed PCI with pneumoperitoneum findings. Based on the diagnosis of CIPO, we evaluated the intestinal peristalsis of the patient by using cine magnetic resonance imaging (MRI).

INTERVENTIONS

Oral medications of 15 g/d of Daikenchuto, 750 mg/d of Metronidazole and Sodium Picosulfate were started for improving the bowel peristaltic movement and decreasing intestinal gas production.

OUTCOMES

A great improvement of CIPO and PCI by multidrug therapy without any surgical treatments for such an unusual case.

LESSONS

This case indicates that SSc can be accompanied with not only CIPO but also PCI as digestive disorders and that cine MRI, which is a definitely beneficial imaging modality, can intelligibly visualize the peristalsis of the intestines and lead to successful medical control by noninvasive treatment.

Recurrent neutrophilic dermatosis of the face: A report of two cases and review of the published work

Recurrent neutrophilic dermatosis of the face is a disease that is morphologically and histopathologically compatible with Sweet's syndrome, but is distributed on the face without fever, laboratory abnormalities or associated disorders. At present, it is unclear whether our cases belong to the chronic and mild variant of Sweet's syndrome or are independent entities. Here, we present two cases of recurrent neutrophilic dermatosis of the face with good response to systemic corticosteroids or potassium iodine, as well as those of cases reported in the published work.

Retiform hemangioendothelioma treated with conservative therapy: report of a case and review of the literature

BACKGROUND

Retiform hemangioendothelioma (RH) is a locally aggressive vascular tumor. Wide surgical excision with tumor-free margins is the standard treatment strategy. However, surgical excision is not an option for lesions near critical anatomical structures, such as those on the face. We report the case of a patient with retiform hemangioendothelioma that responded to non-surgical treatments.

METHODS

We describe the case of a 72-year-old male patient with a retiform hemangioendothelioma on the face that responded to a combination of pulsed dye laser, local corticosteroid injection, and application of imiquimod cream. In addition, we reviewed past case reports of patients with retiform hemangioendothelioma.

RESULTS

Thirty-five cases that describe the management of RH, including the present case, have been reported. Review of the cases indicate a relatively low disease-free survival rate in cases that underwent surgical excision as the initial therapy for retiform hemangioendothelioma.

CONCLUSION

Surgical excision might not be the best therapeutic option. Local control with conservative therapy is an acceptable strategy for lesions in anatomical regions including the face.

Impact of disease severity on work productivity and activity impairment in Japanese patients with atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disease that is characterized by chronic and persisting pruritic and eczematous lesions. There has been no study of work productivity and activity in AD patients in relation to disease severity. The purpose of this study was to examine the impact of disease severity on work productivity and activity impairment (WPAI) in adult AD patients using the Japanese version of the questionnaire. Data were collected from 112 AD patients who visited the Jikei University Hospital. Outcomes as measured by the questionnaire included employment status, total work productivity impairment (TWPI) and total activity impairment (TAI). We investigated the correlation between TWPI or TAI scores and severity scoring of AD (SCORAD) for disease severity and dermatology life quality index (DLQI) for quality of life impairment. Both TWPI and TAI scores were significantly correlated with the SCORAD and DLQI scores (P < 0.001), indicating disease severity is significantly associated with WPAI in Japanese adult AD patients. Further studies are necessary to evaluate the effects of treatments on WPAI for severe AD patients.

A study of serum concentrations and dermal levels of NGF in atopic dermatitis and healthy subjects

Nerve growth factor (NGF) was reported to be increased in the serum and skin of atopic dermatitis (AD) patients, to the extent that serum nerve growth factor levels were proposed to serve as a marker of disease severity. We studied NGF levels in the serum and dermis using skin microdialysis and attempted to correlate them with disease severity. We also examined if potential differences between morning and evening levels of NGF can explain the phenomenon of nocturnal itch. In addition, neurogenic inflammation and itch were induced using histamine iontophoresis in lesional and non-lesional skin and the effect of experimental itch on dermal NGF concentration was examined. We found that systemic (serum) and eczematous skin levels of NGF in AD are significantly lower in comparison to healthy controls. Serum NGF decreases from morning to late afternoon in both groups. Interestingly, serum NGF levels were correlated to disease severity in the morning in AD, although the NGF concentration in AD were significantly lower than in the healthy group. The local itch and neurogenic inflammation induction via experimental histamine reduced local NGF levels in the eczema and non-lesional skin in atopics, but not in the healthy controls, where it was slightly increased. The higher the clinical severity of the eczema, a significantly less pronounced effect of neurogenic inflammation on the local levels of NGF was found. The availability of measurable NGF might be reduced by a higher expression of NGF receptors. The fluctuations of NGF levels during the day suggest a complex modulation of this neurotrophin, potentially linked to stress or to an altered neurophysiological mechanism.

Distinct patterns of brain activity evoked by histamine-induced itch reveal an association with itch intensity and disease severity in atopic dermatitis

BACKGROUND

Little is known about brain mechanisms supporting the experience of chronic puritus in disease states.

OBJECTIVES

To examine the difference in brain processing of histamine-induced itch in patients with active atopic dermatitis (AD) vs. healthy controls with the emerging technique of functional magnetic resonance imaging (fMRI) using arterial spin labelling (ASL).

METHODS

Itch was induced with histamine iontophoresis in eight patients with AD and seven healthy subjects.

RESULTS

We found significant differences in brain processing of histamine-induced itch between patients with AD and healthy subjects. Patients with AD exhibited bilateral activation of the anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), retrosplenial cingulate cortex and dorsolateral prefrontal cortex (DLPFC) as well as contralateral activation of the caudate nucleus and putamen. In contrast, healthy subjects activated the primary motor cortex, primary somatosensory cortex and superior parietal lobe. The PCC and precuneus exhibited significantly greater activity in patients vs. healthy subjects. A significant correlation between percentage changes of brain activation was noted in the activation of the ACC and contralateral insula and histamine-induced itch intensity as well as disease severity in patients with AD. In addition, an association was noted between DLPFC activity and disease severity.

CONCLUSIONS

Our results demonstrate that ASL fMRI is a promising technique to assess brain activity in chronic itch. Brain activity of acute itch in AD seems to differ from that in healthy subjects. Moreover, the activity in cortical areas involved in affect and emotion correlated to measures of disease severity.

In vitro and in vivo characterization of a novel liposomal butorphanol formulation for treatment of pruritus

As yet no transdermal topical formulations have been developed for the treatment of chronic itch. We developed a formulation containing 2 mg butorphanol tartrate in 100 microl purified water encapsulated into multilamellar phospholipid vesicles. Drug permeation experiments were studied with Franz diffusion chambers using human skin in vitro and on rat skin in vivo. Histological analysis of rat skins was performed to evaluate skin irritation of the formulation in vivo. Physical properties showed stable formulation with desirable viscosity. In vitro dermal penetration rate data suggest that there was significant permeation at time-points 2 h and 4 h, and a steady state was achieved afterwards to 24 h. Maximal plasma butorphanol concentration was noted at 2 h and steady state was achieved at 8 h. Visual skin assessment as well as histological analysis of excised rat skin did not demonstrate any evidence of inflammation and irritation. In vitro and in vivo analysis demonstrated release of a consistent amount of butorphanol in a sustained manner for 24 h. This liposomal transdermal delivery formulation could serve as a method to deliver butorphanol for patients with chronic pruritus.

Repetitive scratching and noxious heat do not inhibit histamine-induced itch in atopic dermatitis

BACKGROUND

Repetitive scratching is the most common behavioural response to itch in atopic dermatitis (AD). Patients with chronic itch often report that very hot showers inhibit itch. We recently reported that scratching and noxious heat stimuli inhibit histamine-induced itch in healthy subjects. However, no psychophysical studies have been performed in AD to assess the effects of repetitive heat pain stimuli and scratching on histamine-induced itch.

OBJECTIVES

To examine the effects of repetitive noxious heat and scratching on itch intensity in patients with AD using quantitative sensory testing devices.

METHODS

Itch was induced with histamine iontophoresis in 16 patients with AD in both lesional and nonlesional skin as well as in 10 healthy subjects. Repetitive noxious heat and scratching were applied 3 cm distal to the area of histamine iontophoresis. Subjects rated their perceived intensity of histamine-induced itch with a computerized visual analogue scale.

RESULTS

Our results demonstrate that repetitive noxious heat and scratching do not inhibit itch intensity in lesional and nonlesional AD skin but do so in healthy skin. Of note, both these stimuli increase itch intensity in lesional AD skin.

CONCLUSIONS

Our results strongly suggest that scratching and noxious thermal stimuli have a different effect upon histamine-induced itch perception in patients with AD when compared with healthy controls. This difference may be associated with both peripheral and central sensitization of nerve fibres in AD.

Enhanced skin blood flow and sensitivity to noxious heat stimuli in papulopustular rosacea

BACKGROUND

Although patients with rosacea often complain of increased skin sensitivity, there has been no quantitative sensory testing of this phenomenon. Furthermore, cutaneous blood flow in these patients has not been assessed using state-of-the-art laser Doppler imaging (LDI).

OBJECTIVES

To assess heat pain thresholds and skin blood flow using quantitative thermal sensory testing and LDI in patients with untreated rosacea.

METHODS

Of the total 24 subjects enrolled, 8 had papulopustular rosacea (PPR), 8 had erythematotelangiectatic rosacea (ETR) and 8 were control subjects. Subjective burning perception, heat pain threshold, skin blood flow, and skin temperature was assessed in all subjects. In the ETR and PPR groups, two areas were compared: affected and nonaffected.

RESULTS

Heat pain thresholds of areas affected by rosacea were lower than those of nonaffected areas. In addition, subjective burning perception was increased in rosacea patients when compared with control subjects. Although PPR-affected skin had elevated skin blood flow when compared with nonaffected skin, this was not significant for ETR-affected skin.

LIMITATIONS

The small number of subjects enrolled was the main limitation.

CONCLUSION

This study showed enhanced sensitivity to noxious heat stimuli in rosacea-affected skin, which was more prominent in the PPR group.

Nocturnal itch: why do we itch at night?

Pruritus is exacerbated at night in many systemic and dermatological diseases, resulting in reports of significantly diminished quality of life and sleep disturbances. At present, the underlying mechanisms responsible for night-time itching are not well understood. Nocturnal pruritus may be related to the circadian rhythm of itch mediators and possibly the disruption of such patterns. Diurnal changes in skin physiology, such as temperature and barrier function, may also play a role. Currently, the paucity of specific treatment options for nocturnal pruritus is alarming and needs to be addressed by future research. This review describes the scale of the problem associated with nocturnal pruritus, the impact it has on patients, possible underlying mechanisms and, lastly, treatment options.

Skin barrier structure and function and their relationship to pruritus in end-stage renal disease

BACKGROUND

The relationship between dry skin and uraemic pruritus remains controversial. In addition, there is a lack of published data describing the structure and function of the stratum corneum (SC) in end-stage renal disease (ESRD). The purpose of the present study was to assess the function and structure of the skin barrier in patients with ESRD and to correlate any abnormalities with uraemic pruritus.

METHODS

Thirty-eight subjects participated in the study; 20 with ESRD and 18 healthy controls. Subjects underwent evaluation of SC integrity and permeability barrier recovery, SC surface pH, pruritus and dry skin. The content of glycerol, an important endogenous humectant, was assessed in D-squame tape strips from seven patients with ESRD. Skin biopsies from six of these patients were examined by electron microscopy using ruthenium tetroxide (Ru04)-post-fixation.

RESULTS

Although SC integrity was impaired in ESRD patients (P = 0.001), there were no significant differences in permeability barrier recovery rates between ESRD subjects and controls. However, there was a high significant negative correlation between SC glycerol content and dry skin in the arms of ESRD subjects (r = -0.866, P = 0.01). Yet, there was no consistent correlation between pruritus and either dry skin, SC integrity, glycerol content or surface pH. Electron microscopy revealed no significant ultra-structural abnormalities, with particular reference to the lipid bi-layer.

CONCLUSIONS

SC integrity, but not permeability barrier recovery, is impaired in dialysis patients. Although dry skin in ESRD is associated with reduced SC glycerol levels, the ultra-structure appears to be unaffected.

Menthol: a refreshing look at this ancient compound

Menthol is a naturally occurring cyclic terpene alcohol of plant origin, which has been used since antiquity for medicinal purposes. Its use in dermatology is ubiquitous, where it is frequently part of topical antipruritic, antiseptic, analgesic, and cooling formulations. Despite its widespread use, it was only recently that the mechanism by which menthol elicits the same cool sensation as low temperature was elucidated upon, with the discovery of the TRPM8 receptor. Although almost 5 years have passed since the discovery of this receptor, many dermatologists are still unaware of menthol's underlying target. The purpose of this review is to highlight the recent advances in the mechanism of action of menthol and to provide an overview of its dermatologic applications.