Itch in Atopic Dermatitis - What Is New?
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ABSTRACT:
SUBMITTER: Legat FJ
PROVIDER: S-EPMC8137993 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Itch is a defining symptom of atopic dermatitis. Crosstalk between keratinocytes, the immune system and non-histaminergic sensory nerves is responsible for the pathophysiology of chronic itch in atopic dermatitis. An expanding understanding of the contribution of the nervous system and its interaction with immune pathways in atopic itch are helping to identify new therapeutic strategies.
| S-EPMC7027518 | biostudies-literature
Project description:Several studies show that itch and scratching cannot only be induced by pruritogens like histamine or cowhage, but also by the presentation of certain (audio-) visual stimuli like pictures on crawling insects or videos showing other people scratching. This phenomenon is coined "Contagious itch" (CI). Due to the fact that CI is more profound in patients with the chronic itchy skin disease atopic dermatitis (AD), we believe that it is highly relevant to study brain processing of CI in this group. Knowledge on brain areas involved in CI in AD-patients can provide us with useful hints regarding non-invasive treatments that AD-patients could profit from when they are confronted with itch-inducing situations in daily life. Therefore, this study investigated the brain processing of CI in AD-patients. 11 AD-patients underwent fMRI scans during the presentation of an itch inducing experimental video (EV) and a non-itch inducing control video (CV). Perfusion based brain activity was measured using arterial spin labeling functional MRI. As expected, the EV compared to the CV led to an increase in itch and scratching (p < 0.05). CI led to a significant increase in brain activity in the supplementary motor area, left ventral striatum and right orbitofrontal cortex (threshold: p < 0.001; cluster size k > 50). Moreover, itch induced by watching the EV was by trend correlated with activity in memory-related regions including the temporal cortex and the (pre-) cuneus as well as the posterior operculum, a brain region involved in itch processing (threshold: p < 0.005; cluster size k > 50). These findings suggest that the fronto-striatal circuit, which is associated with the desire to scratch, might be a target region for non-invasive treatments in AD patients.
| S-EPMC5524890 | biostudies-other
Project description:BackgroundPsychological factors are known to significantly modulate itch in patients suffering from chronic itch. Itch is also highly susceptible to both placebo and nocebo (negative placebo) effects. Brain activity likely supports nocebo-induced itch, but is currently unknown.MethodsWe collected functional MRI (fMRI) data from atopic dermatitis (AD) patients, in a within-subject design, and contrast brain response to nocebo saline understood to be allergen vs open-label saline control. Exploratory analyses compared results to real allergen itch response and placebo responsiveness, evaluated in the same patients.ResultsNocebo saline produced greater itch than open saline control (P < 0.01). Compared to open saline, nocebo saline demonstrated greater fMRI response in caudate, dorsolateral prefrontal cortex (dlPFC), and intraparietal sulcus (iPS) - brain regions important for cognitive executive and motivational processing. Exploratory analyses found that subjects with greater dlPFC and caudate activation to nocebo-induced itch also demonstrated greater dlPFC and caudate activation, respectively, for real allergen itch. Subjects reporting greater nocebo-induced itch also demonstrated greater placebo reduction of allergen-evoked itch, suggesting increased generalized modulation of itch perception.ConclusionsOur study demonstrates the capacity of nocebo saline to mimic both the sensory and neural effects of real allergens and provides an insight to the brain mechanisms supporting nocebo-induced itch in AD, thus aiding our understanding of the role that expectations and other psychological factors play in modulating itch perception in chronic itch patients.
| S-EPMC4609272 | biostudies-literature
Project description:BackgroundPatients with atopic dermatitis (AD) exhibit heterogeneous clinical phenotypes, reflecting different combinations of itch and lesional severity. AD with severe itch but clear-moderate lesions, also known as itch-dominant AD, is a common clinical phenotype.ObjectivesTo evaluate abrocitinib efficacy in patients with moderate-to-severe AD who have itch-dominant AD.MethodsThis post hoc analysis includes pooled data from clinical trials of patients with moderate-to-severe AD receiving abrocitinib (100 or 200 mg) as monotherapy (phase 2b; phase 3 JADE MONO-1 and JADE MONO-2) or in combination with topical therapy (phase 3 JADE COMPARE). Data from the ongoing long-term JADE EXTEND trial (data cutoff April 2020) were also evaluated. Itch-dominant AD was defined as baseline Peak Pruritus Numerical Rating Scale (PP-NRS) score of 7-10 and Investigator's Global Assessment of 0-3 or Eczema Area and Severity Index of 0‒21. Assessments included a ≥4-point improvement in PP-NRS (PP-NRS4), PP-NRS score of 0 (no itch) or 1 (little itch) in patients with PP-NRS score ≥2 at baseline, ≥4-point improvement from baseline in Patient-Oriented Eczema Measure (POEM-4), Patient Global Assessment (PtGA) of clear or almost clear, and Dermatology Life Quality Index (DLQI) score of 0 or 1 (no impact or little impact of AD on quality of life [QoL]).ResultsIn the pooled monotherapy trials, 37% of patients had itch-dominant AD at baseline. As early as Week 2, more patients with itch-dominant AD achieved PP-NRS4 with abrocitinib 100 mg (35%) and abrocitinib 200 mg (57%) versus placebo (7%); 6% and 22% versus 0%, respectively, achieved PP-NRS 0/1. More patients achieved a PtGA of clear/almost clear at Week 12 with abrocitinib 100 mg (28%) and abrocitinib 200 mg (45%) than placebo (9%). Additionally, abrocitinib led to clinically meaningful improvements in POEM and DLQI. Most patients with itch-dominant AD experienced itch improvement over time with abrocitinib monotherapy or with concomitant topical therapy; 86%-87% and 62%-67% of patients had no itch-moderate itch and clear-moderate lesions by weeks 24 and 48, respectively.ConclusionsAbrocitinib is highly efficacious in patients with itch-dominant AD, demonstrating rapid, deep, and sustained improvements in itch and clinically meaningful improvements in patients' QoL.Trial registration numbersNCT02780167; NCT03349060; NCT03575871; NCT03720470; NCT03422822.
| S-EPMC11297436 | biostudies-literature
Project description:Accumulated evidence on type 2 inflammation-associated itch in atopic dermatitis has recently been reported. Crosstalk between the immune and nervous systems (neuroimmune interactions) is prominent in atopic dermatitis research, particularly regarding itch and inflammation. A comprehensive understanding of bidirectional neuroimmune interactions will provide insights into the pathogenesis of itch and its treatment. There is currently no agreed cure for itch in atopic dermatitis; however, increasing numbers of novel and targeted biologic agents have potential for its management and are in the advanced stages of clinical trials. In this review, we summarize and discuss advances in our understanding of type 2 inflammation-associated itch and implications for its management and treatment in patients with atopic dermatitis.
| S-EPMC8618746 | biostudies-literature
Project description:Chronic itch remains a highly prevalent disorder with limited treatment options. Most chronic itch diseases are thought to be driven by both the nervous and immune systems, but the fundamental molecular and cellular interactions that trigger the development of itch and the acute-to-chronic itch transition remain unknown. Here, we show that skin-infiltrating neutrophils are key initiators of itch in atopic dermatitis, the most prevalent chronic itch disorder. Neutrophil depletion significantly attenuated itch-evoked scratching in a mouse model of atopic dermatitis. Neutrophils were also required for several key hallmarks of chronic itch, including skin hyperinnervation, enhanced expression of itch signaling molecules, and upregulation of inflammatory cytokines, activity-induced genes, and markers of neuropathic itch. Finally, we demonstrate that neutrophils are required for induction of CXCL10, a ligand of the CXCR3 receptor that promotes itch via activation of sensory neurons, and we find that that CXCR3 antagonism attenuates chronic itch.
| S-EPMC6884397 | biostudies-literature
Project description:Atopic dermatitis (AD) is a highly prevalent, itchy inflammatory skin disorder that is thought to arise from a combination of skin barrier defect and immune dysregulation. Kallikreins (KLK), a family of serine proteases with a diverse array of homeostatic functions, including skin desquamation and innate immunity, are hypothesized to contribute to AD pathogenesis. However, their precise role in AD has not been clearly defined. In this study, RNA sequencing analyses identified KLK7 as the most abundant and differentially expressed KLK in both human AD and murine AD-like skin. Further, in mice, Klk7 expression was localized to the epidermis in both steady state and inflammation. Unexpectedly, KLK7 was dispensable for the development of AD-associated skin inflammation. Instead, KLK7 was selectively required for AD-associated chronic itch. Even without the alleviation of skin inflammation, KLK7-deficient mice exhibited significantly attenuated scratching, compared with littermate controls, after AD-like disease induction. Collectively, our findings indicate that KLK7 promotes AD-associated itch independently from skin inflammation and reveal a previously unrecognized epidermal-neural mechanism of AD associated itch.
| S-EPMC7247952 | biostudies-literature
Project description:Anecdotal evidence suggests that 'contagious' itch occurs in daily life when we see other people itch and scratch. This phenomenon has not previously been studied systematically, and factors which can amplify itch perception were unknown.We investigated whether exposure to visual cues of itch can induce or intensify itch in healthy subjects and patients with atopic dermatitis (AD).Participants received histamine or a saline control delivered to the forearm and were asked to watch short video clips of people scratching. Spontaneous scratching induced by visual cues was monitored and analysed.Patients with AD reported a higher itch intensity and scratched more frequently while watching itch videos, even in the presence of mock itch stimuli.Human susceptibility to develop itch when exposed to visual cues is confirmed; it appears to be amplified in patients with AD. These findings suggest that interpersonal social cues can dramatically alter the subjective sensory experience of itch.
| S-EPMC3110738 | biostudies-literature
Project description:Atopic dermatitis (AD) is a chronic skin disease, which is associated with intense itch, skin barrier dysfunction and eczematous lesions. Aberrant IL-20 expression has been implicated in numerous inflammatory diseases, including psoriasis. However, the role of IL-20 in AD remains unknown. Here, RNA-seq, Q-PCR, and immunocytochemistry were utilized to examine disease-driven changes of IL-20 and its cognate receptor subunits in skin from healthy human subjects, AD patients and murine AD-models. Calcium imaging, knockdown and cytokine array were used to investigate IL-20-evoked responses in keratinocytes and sensory neurons. The murine cheek model and behavioral scoring were employed to evaluate IL-20-elicited sensations in vivo. We found that transcripts and protein of IL-20 were upregulated in skin from human AD and murine AD-like models. Topical MC903 treatment in mice ear enhanced IL-20R1 expression in the trigeminal sensory ganglia, suggesting a lesion-associated and epidermal-driven mechanism for sensitization of sensory IL-20 signaling. IL-20 triggered calcium influx in both keratinocytes and sensory neurons, and promoted their AD-related molecule release and transcription of itch-related genes. In sensory neurons, IL-20 application increased TLR2 transcripts, implicating a link between innate immune response and IL-20. In a murine cheek model of acute itch, intradermal injection IL-20 and IL-13 elicited significant itch-like behavior, though only when co-injected. Our findings provide novel insights into IL-20 function in peripheral (skin-derived) itch and clinically relevant intercellular neuron-epidermal communication, highlighting a role of IL-20 signaling in the pathophysiology of AD, thus forming a new basis for the development of a novel antipruritic strategy via interrupting IL-20 epidermal pathways.
| S-EPMC9321592 | biostudies-literature
Project description:PAR2 has been proposed to contribute to lesion formation and intense itch in atopic dermatitis. Here, we tested the ability of a cell-penetrating pepducin, PZ-235, to mitigate the potentially deleterious effects of PAR2 in models of atopic dermatitis. PZ-235 significantly inhibited PAR2-mediated expression of inflammatory factors NF-κB, TSLP, TNF-α, and differentiation marker K10 by 94%-98% (P < 0.001) in human keratinocytes and suppressed IL-4 and IL-13 by 68%-83% (P < 0.05) in mast cells. In delayed pepducin treatment models of oxazolone- and DNFB-induced dermatitis, PZ-235 significantly attenuated skin thickening by 43%-100% (P < 0.01) and leukocyte crusting by 57% (P < 0.05), and it inhibited ex vivo chemotaxis of leukocytes toward PAR2 agonists. Daily PZ-235 treatment of filaggrin-deficient mice exposed to dust mite allergens for 8 weeks significantly suppressed total leukocyte and T-cell infiltration by 50%-68%; epidermal thickness by 60%-77%; and skin thickening, scaling, excoriation, and total lesion severity score by 46%-56%. PZ-235 significantly reduced itching caused by wasp venom peptide degranulation of mast cells in mice by 51% (P < 0.05), which was comparable to the protective effects conferred by PAR2 deficiency. Taken together, these results suggest that a PAR2 pepducin may confer broad therapeutic benefits as a disease-modifying treatment for atopic dermatitis and itch.
| S-EPMC6830517 | biostudies-literature