Interleukin-31, a Potent Pruritus-Inducing Cytokine and Its Role in Inflammatory Disease and in the Tumor Microenvironment

Role of IL-4 and IL-13 in Cutaneous T Cell Lymphoma

The interleukins IL-4 and IL-13 are increasingly recognized contributors to the pathogenesis of cutaneous T cell lymphomas (CTCLs), and their role in disease-associated pruritus is accepted. The prevailing Th2 profile in advanced CTCL underscores the significance of understanding IL-4/IL-13 expression dynamics from the early stages of disease, as a shift from Th1 to Th2 may explain CTCL progression. Targeted agents blocking key cytokines of type 2 immunity are established therapeutics in atopic disorders and have a promising therapeutic potential in CTCL, given their involvement in cutaneous symptoms and their contribution to the pathogenesis of disease. IL-4, IL-13, and IL-31 are implicated in pruritus, offering therapeutic targets with dupilumab, tralokinumab, lebrikizumab, and nemolizumab. This review analyzes current knowledge on the IL-4/IL-13 axis in mycosis fungoides and Sezary syndrome, the most common types of CTCL, examining existing literature on the pathogenetic implications with a focus on investigational treatments. Clinical trials and case reports are required to shed light on novel uses of medications in various diseases, and ongoing research into the role of IL-4/IL-13 axis blockers in CTCL therapy might not only improve the management of disease-related pruritus but also provide in-depth insights on the pathophysiologic mechanisms of CTCL.

Nemolizumab: First Approval

Nemolizumab is a subcutaneously administered humanized anti-interleukin-31 (IL-31) receptor A (IL-31RA) monoclonal antibody that is being developed by Chugai Pharmaceutical Co. Ltd, Maruho Co. Ltd and Galderma Pharma S.A. for the treatment of skin diseases, including atopic dermatitis (AD), AD associated pruritus (ADaP), prurigo nodularis (PN), chronic kidney disease associated pruritus (CKDaP) and systemic sclerosis (SSc). IL-31 is a neuroimmune cytokine that induces itch, inflammation, keratinocyte differentiation and fibroblast activation in chronic pruritic skin diseases. Nemolizumab (Mitchga^® Syringes) was approved in Japan on 28 March 2022 for use in adults and children over the age of 13 years for the treatment of itch associated with AD (only when existing treatment is insufficiently effective). This article summarizes the milestones in the development of nemolizumab leading to this first approval.

The Effects of Cannabinoid Agonist, Heat Shock Protein 90 and Nitric Oxide Synthase Inhibitors on Increasing IL-13 and IL-31 Levels in Chronic Pruritus

BACKGROUND

Heat shock protein 90 (Hsp90) inhibitor and cannabinoid agonists ameliorate dry skin-induced chronic itch. We have recently reported that cannabinoids, hsp90 and nitric oxide (NO) are involved in dry skin-induced itch. Here, we investigated the contribution of the Th2 cell signaling pathway to the antipruritic effect of the hsp90 inhibitor 17-Alilamino-17-demethoxygeldanamycin (17-AAG), nitric oxide synthase (NOS) inhibitor Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) and cannabinoid agonist WIN 55,212-2 on a dry skin-induced scratch.

METHODS

Dry skin-induced chronic itching was created by topical application of AEW (acetone/diethyl ether/water). WIN 55,212-2 (1 mg/kg, i.p.), L-NAME (1 mg/kg, i.p.) and increasing doses of 17-AAG (1, 3 and 5 mg/kg,i.p.) were administered to Balb/c mice (for each group, n = 6). After these applications, skin tissues were taken from the nape region of all of the mice. Gene and protein expressions of IL-13 and IL-31 were evaluated in skin tissues by RT-PCR and immunohistochemistry, respectively.

RESULTS

IL-13 and IL-31 mRNA expressions and immune positive cell counts were increased in the AEW applied groups. WIN 55,212-2 reduced both of the increased cytokines levels, while L-NAME decreased only the IL-13. 17-AAG dose-dependently reduced the increased cytokine levels. IL-13 and IL-31 levels significantly decreased following the co-administration of these agents.

CONCLUSION

These results show that increased levels of IL-13 and IL-31 are associated with pruritus. Hsp90 inhibition and cannabinoid system activation may induce antipruritic effects through down-regulation of these cytokines.

The emerging role of the neuroimmune cytokine interleukin-31 in chronic inflammatory skin diseases

Chronic inflammatory skin diseases pose significant challenges for both patients and clinicians worldwide. Atopic dermatitis (AD), the most common of these diseases, affects up to 8% of the adult population depending on geographic location and demographic group, while prurigo nodularis (PN) is a less common disease that causes significant burden. In these inflammatory skin conditions, pruritus is a cardinal symptom. Interleukin 31 (IL-31), described as a neuroimmune modulator, has been shown to have a prominent role in both inflammation and itch. IL-31 acts through a receptor complex consisting of IL-31 receptor α (IL-31RA) and oncostatin M receptor β (OSMRβ). IL-31 is produced by a variety of cells, including type 2 helper T cells, and IL-31 signaling can activate three important pathways: JAK/STAT, P13K/AKT, and ERK/MAPK. IL-31 is elevated in AD and PN, and is thought to induce chemokine genes CCL1, CCL17, and CCL22. The chemokines recruit T cells to affected skin, where more IL-31 is secreted. The IL-31 receptor complex is also abundant in dorsal root ganglia in human tissue, home of primary sensory neurons and the distal source of "itch sensations". IL-31 and its receptor complex have an important role in chronic inflammatory diseases, including AD and PN, and blocking the IL-31/IL-31RA signaling may represent an important new therapeutic approach for these diseases, which continue to have significant unmet medical needs.

Rationale and design of the multicentric, double-blind, double-placebo, randomized trial APrepitant versus HYdroxyzine in association with cytoreductive treatments for patients with myeloproliferative neoplasia suffering from Persistent Aquagenic Pruritus. Trial acronym: APHYPAP

Background

Aquagenic pruritus (AP), an intense sensation of scratching induced after water contact, is the most troublesome aspect of BCR-ABL1-negative myeloproliferative neoplasms (MPNs). Mostly described in polycythemia vera (PV, ~ 40%), it is also present in essential thrombocythemia (ET) and primary myelofibrosis (PMF) (10%). Even if this symptom can decrease or disappear under cytoreductive treatments, 30% of treated MPN patients still persist with a real impact on the quality of life (QoL). Because its pathophysiology is poorly understood, efficient symptomatic treatments of AP are missing. The neuropeptide substance P (SP) plays a crucial role in the induction of pruritus. Several studies showed the efficacy of aprepitant, an antagonist of SP receptor (NK-1R), in the treatment of chronic pruritus but never evaluated in AP. The objectives of APHYPAP are twofold: a clinical aim with the evaluation of the efficacy of two drugs in the treatment of a persistent AP for MPN patients and a biological aim to find clues to elucidate AP pathophysiology.

Methods/design

A multicentric, double-blind, double-placebo, randomized study will include 80 patients with MPN (PV or ET or PMF) treated since at least 6 months for their hemopathy but suffering from a persistent AP (VAS intensity ≥6/10). Patients will be randomized between aprepitant (80 mg daily) + placebo to match to hydroxyzine OR hydroxyzine (25 mg daily) + placebo to match to aprepitant for 14 days. At D0, baseline information will be collected and drugs dispense. Outcome measures will be assessed at D15, D30, D45, and D60. The primary study endpoint will be the reduction of pruritus intensity below (or equal) at 3/10 on VAS at D15. Secondary outcome measures will include the number of patients with a reduction or cessation of AP at D15 or D60; evaluation of QoL and AP characteristics at D0, D15, D30, D45, and D60 with MPN-SAF and AP questionnaires, respectively; modification of plasmatic concentrations of cytokines and neuropeptides at D0, D15, D30, and D60; and modification of epidermal innervation density and pruriceptor expression at D0 and D15.

Discussion

The APHYPAP trial will examine the efficacy of aprepitant vs hydroxyzine (reference treatment for AP) to treat persistent AP in MPN patients. The primary objective is to demonstrate the superiority of aprepitant vs hydroxyzine to treat persistent AP of MPN patients. The treatment received will be considered efficient if the AP intensity will be reduced at 3/10 or below on VAS after 14 days of treatment. The results of this study may provide a new treatment option for this troublesome symptom and also give us more insights in the pathophysiology understanding of AP.

Trial registration

APHYPAP. NCT03808805, first posted: January 18, 2019; last update posted: June 10, 2021. EudraCT 2018-090426-66