Itch intensity in prurigo nodularis is closely related to dermal interleukin-31, oncostatin M, IL-31 receptor alpha and oncostatin M receptor beta.

Prurigo nodularis (PN) is a chronic skin dermatosis with hyperkeratotic and intensely pruritic nodules. Managing PN-associated itch is difficult because its aetiology is still unknown. This study aimed to investigate the correlation between itch intensity in PN and the expression of a pruritogenic cytokine interleukin (IL)-31, its receptor complex components IL-31 receptor α (IL-31RA) and oncostatin M receptor ß (OSMRß), and oncostatin M (OSM), which is a ligand of OSMR ß, through immunofluorescence staining examination. Itch intensity in PN was closely correlated with the number of dermal IL-31(+) cells (Spearman's r = 0.551, p < 0.05), dermal IL-31RA(+) cells (r = 0.475, p < 0.05) and dermal OSM(+) cells (r = 0.505, p < 0.05). In addition, the number of dermal OSMRß (+) cells was increased in PN (t test, p < 0.05), despite not being correlated with itch intensity (Spearman's r = 0.375, p > 0.05). Major cellular sources of dermal IL-31 were T cells (27.0% of total IL-31-expressing cells) and macrophages (35.0%), while those of OSM were mainly T cells (49.8%) and mast cells (26.8%). IL-31RA-expressing dermal cells were mostly mast cells (49.3%) and macrophages (36.6%), and OSMRß was mainly expressed by macrophages (51.8%) in the dermis. These findings indicate that IL-31 (mainly from macrophages and T cells) and OSM (principally from T cells and mast cells) stimulate dermal cells expressing IL-31RA and OSMRß (e.g. macrophages), which may further promote itch and inflammation in PN. This complex dermal milieu of cell/cytokine/receptor network can be a therapeutic target for PN-associated itch.

A New Generation of Treatments for Itch.

For decades, antihistamines have been the mainstay of treatment for chronic pruritus, yet they often only work by making patients drowsy and forgetful of their itch. A new era of antipruritic drugs is quickly approaching, presenting more effective treatments for patients suffering from chronic itch. Several treatments have been developed targeting specific receptors in the nervous system, such as the transient receptor potential channels, sodium channels, neurokinin-1 receptors, opioid receptors, and many more. Additionally, antipruritic therapies developed to work on the immune system have become more targeted, leading to greater safety and efficacy measures. These include crisaborole, several interleukin antagonists, and janus kinase inhibitors. The promising results presented with these new antipruritic therapies allow physicians to be better equipped to treat their itchy patients.

Psychiatric Comorbidities in Non-psychogenic Chronic Itch, a US-based Study.

Research suggests that itch and psychiatric diseases are intimately related. In efforts to examine the prevalence of psychiatric diagnoses in patients with chronic itch not due to psychogenic causes, we conducted a retrospective chart review of 502 adult patients diagnosed with chronic itch in an outpatient dermatology clinic specializing in itch and assessed these patients for a co-existing psychiatric disease. Psychiatric disease was identified and recorded based on ICD-10 codes made at any point in time which were recorded in the patient's electronic medical chart, which includes all medical department visits at the University of Miami. Fifty-five out of 502 (10.9%) of patients were found to have a comorbid psychiatric diagnosis based on ICD-10 codes. The most common psychiatric diagnoses were anxiety disorders (45.5%), followed by major depressive disorder (36.4%). There was no significant association of any specific type of itch to a particular psychiatric disorder. No unique itch characteristics were noted in patients with underlying psychiatric diagnoses.

Chronic itch management: therapies beyond those targeting the immune system.

OBJECTIVE: Chronic itch can be a debilitating, unrelenting symptom. Over the years, we have advanced our knowledge about immune-mediated itch (eg, atopic dermatitis) and have developed several treatments targeting these immune pathways. Chronic itch that is noninflammatory in nature is more elusive. However, we have gained some understanding of the neural component mediating itch and have made progress in treating this challenging symptom. DATA SOURCES: A comprehensive literature search was conducted, and data and literature were reviewed on the topics of chronic itch, its pathophysiology, and nonimmunological treatments for chronic itch that work on the nerves. STUDY SELECTIONS: Basic science papers, review articles, case reports, and clinical trial data were considered. RESULTS: A variety of topical and systemic therapies targeting the nerves have shown effectiveness in treating patients with chronic itch of different types. CONCLUSION: Treating chronic itch may be challenging, but an arsenal of treatments are available and many are on the horizon as we expand our knowledge of mechanisms of itch and the neural receptors involved.

A Case of Friction Alopecia in a Healthy 15-Year-Old Girl.

Friction alopecia is a non-scarring alopecia that causes hair breakage and may cause trichorrhexis nodosa. We report a case of a 15-year-old girl with self-inflicting friction alopecia that demonstrated broken hairs and proximal trichorrhexis nodosa on dermoscopy. We review various causes of friction alopecia and clinical findings, as well as trichorrhexis nodosa.