Proactive maintenance therapy of canine atopic dermatitis with the anti-IL-31 lokivetmab. Can a monoclonal antibody blocking a single cytokine prevent allergy flares?

Update on the role of cytokines and chemokines in canine atopic dermatitis

BACKGROUND

Cytokines and chemokines play central roles in the pathogenesis of canine atopic dermatitis (cAD). Numerous studies have been published and provide new insights into their roles in cAD.

OBJECTIVES

To summarise the research updates on the role of cytokines and chemokines in the pathogenesis of cAD since the last review by the International Committee on Allergic Diseases of Animals in 2015.

MATERIAL AND METHODS

Online citation databases, abstracts and proceedings from international meetings on cytokines and chemokines relevant to cAD that had been published between 2015 and 2022 were reviewed.

RESULTS

Advances in technologies have allowed the simultaneous analysis of a broader range of cytokines and chemokines, which revealed an upregulation of a multipolar immunological axis (Th1, Th2, Th17 and Th22) in cAD. Most studies focused on specific cytokines, which were proposed as potential novel biomarkers and/or therapeutic targets for cAD, such as interleukin-31. Most other cytokines and chemokines had inconsistent results, perhaps as a consequence of their varied involvement in the pathogenesis of different endotypes of cAD.

CONCLUSIONS AND CLINICAL RELEVANCE

Inconsistent results for many cytokines and chemokines illustrate the difficulty of studying the complex cytokine and chemokine networks in cAD, and highlight the need for more comprehensive and structured studies in the future.

Clinical Guidelines for the Use of Antipruritic Drugs in the Control of the Most Frequent Pruritic Skin Diseases in Dogs

Pruritus is a common clinical sign in many skin disorders and is currently the main complaint in canine dermatology. Pruritic skin diseases can affect the quality of life of dogs and their owners. Several families of antipruritic drugs are available to help control pruritus in dogs. The aim of this review is to help practitioners select the most appropriate symptomatic treatment in the most frequent situations of dermatological pruritus in dogs. The molecules reviewed here are systemic and topical glucocorticoids, antihistamines, ciclosporin, oclacitinib and lokivetmab. A level of evidence (1, 2 or 3) has been established according to a detailed algorithm for each individual study in the literature published between 1990 and March 2021. The guidelines result from evidence grading using the strength of recommendation taxonomy (SoRT) and clinical recommendations using a thorough methodology.

A Pilot Study To Establish an Ovalbumin-induced Atopic Dermatitis Minipig Model

Introduction

Because minipig skin is similar to human skin in anatomy and physiology, establishing an atopic dermatitis (AD) minipig model seems meaningful.

Material and Methods

We applied 1-fluoro-2,4-dinitrobenzene (DNFB) or ovalbumin onto the back skin of five Yucatan minipigs aged 8-10 months and 19 kg in median weight. Two minipigs with the same parameters served as controls.

Results

Both DNFB and ovalbumin mediated epithelial hyperplasia, spongiosis, and immune cell infiltration in the dermis, which is a typical histopathological feature of AD. Moreover, AD upregulated the Th1- and Th2-related cytokine expressions in DNFB- or in ovalbumin-treated skin. Notably, AD-induced minipigs exhibited greater cytokine serum concentrations.

Conclusion

Histopathological finding and cytokine analysis revealed that DNFB or ovalbumin mediates AD. However, ovalbumin-treated minipig is a more reliable and precise AD model owing to the DNFB-induced severe skin damage. In summary, ovalbumin-treated skin shows similar AD as human in histopathological and molecular analysis.

IL-31 and IL-31 receptor expression in acute experimental canine atopic dermatitis skin lesions

BACKGROUND

To optimise the interleukin (IL)-31-blocking therapy in atopic dermatitis (AD), an understanding of the chronology in the expression of IL-31 and its receptor (IL-31RA) is needed.

HYPOTHESIS/OBJECTIVES

(i) To assess the chronological expression of IL-31 in canine AD skin lesions, (ii) to compare it with serum IL-31 levels and macroscopic skin lesion scores, and (iii) to determine the identity of IL-31- and IL-31RA-positive cells.

ANIMALS

Four atopic dogs sensitised to house dust mites.

METHODS AND MATERIALS

Skin and blood samples were obtained 0 h, 24 h, 48 and 96 h after allergen provocation. IL-31 and IL-31RA single-staining immunofluorescence (IF), as well as IL-31/CD3, IL-31/CD4 and IL-31RA/β3-tubulin double-staining IF were performed. The IL-31-positive cells were counted subjectively.

RESULTS

The peak IL-31 expression for three of four dogs occurred 24 h or 48 h postchallenge; it started to decrease at 96 h. There was no significant correlation between the IL-31 expression scores and the serum IL-31 concentrations or the macroscopic skin lesion scores (P = 0.35 and P = 0.36, respectively). The majority of IL-31-positive cells were positive for CD3 (range 91-100%) and CD4 (range 63-100%), indicating that they were helper T (Th) cells. Unexpectedly, sebaceous glands were strongly immunolabelled with IL-31; the extinction of this positivity after immunoabsorption with IL-31 further supported the validity of this immunostaining. The IL-31RA was visualised on keratinocytes and a small proportion of dermal nerves.

CONCLUSIONS AND CLINICAL IMPORTANCE

The early and transient production of IL-31 by Th cells supports the concept of using IL-31 inhibiting strategies as a proactive therapy to prevent flares of AD skin lesions.

Weekly topical therapy based on plant extracts combined with lokivetmab in canine atopic dermatitis

BACKGROUND

Lokivetmab is an effective treatment for atopic dermatitis (AD) in dogs. The aim of this prospective study was to determine if topical products containing plant extracts could enhance the clinical efficacy of lokivetmab.

ANIMALS

Thirty atopic dogs were included.

METHODS AND MATERIALS

Dogs were allocated randomly to be treated either with a single injection of lokivetmab (mean dose 1.34 mg/kg; Group A) or to a single injection (mean dose 1.28 mg/kg) coupled with a weekly topical treatment using a shampoo and a spot-on specifically designed to improve skin barrier defect (Group B). Clinical parameters evaluated included pruritus (pruritus Visual Analog Scale) and skin lesions (Canine Atopic Dermatitis Lesion Index, CADLI); cosmetic evaluation, and owner and investigator global assessment of efficacy (OGATE) also were carried out. Dogs were re-examined after 10, 17 and 31 days, and until a clinical relapse occurred.

RESULTS

An improvement was noted for all dogs, with scores being significantly better in dogs in Group B than in those in Group A; after 10 days for cosmetic evaluation, 17 days for pruritus (P = 0.039) and OGATE, and 31 days for CADLI (P = 0.043). A longer-lasting remission was noted in Group B compared to Group A; dogs receiving the combined treatment showed an extended time to flare compared to dogs treated with lokivetmab alone (P = 0.012).

CONCLUSIONS AND CLINICAL IMPORTANCE

This study suggests that combining lokivetmab with topical therapies designed to repair the skin barrier potentially have value in the treatment of AD in dogs.

Atopic Dermatitis in Domestic Animals: What Our Current Understanding Is and How This Applies to Clinical Practice

Atopic dermatitis is a clinical syndrome that affects both people and animals. Dogs closely mimic the complexity of the human skin disease, and much progress has been made in recent years in terms of our understanding of the role of skin impairment and the identification of new treatments. Cats and horses also develop atopic syndromes which include both cutaneous and respiratory signs, yet studies in these species are lagging. It is now recognized that atopic dermatitis is not a single disease but a multifaceted clinical syndrome with different pathways in various subgroups of patients. Appreciating this complexity is clinically relevant as we develop more targeted treatments which may work well in some patients but not in others. Different phenotypes of atopic dermatitis have been described in dogs, and it is possible that phenotypes related to breed and age may exist in other animals similar to how they are described in people. The awareness of different mechanisms of disease leads to the desire to correlate different phenotypes with specific biomarkers and responses to treatment. In this review, the current understanding and updated information on atopic syndrome in animals are described, highlighting opportunities for further studies in the future.

Interleukin-31 and Pruritic Skin

Skin inflammation often evokes pruritus, which is the major subjective symptom in many inflammatory skin diseases such as atopic dermatitis and prurigo nodularis. Pruritus or itch is a specific sensation found only in the skin. Recent studies have stressed the pivotal role played by interleukin-31 (IL-31) in the sensation of pruritus. IL-31 is produced by various cells including T helper 2 cells, macrophages, dendritic cells and eosinophils. IL-31 signals via a heterodimeric receptor composed of IL-31 receptor A (IL-31RA) and oncostatin M receptor β. Recent clinical trials have shown that the anti-IL-31RA antibody nemolizumab can successfully decrease pruritus in patients with atopic dermatitis and prurigo nodularis. The IL-31 pathway and pruritic skin are highlighted in this review article.

Interleukin 31 in insect bite hypersensitivity-Alleviating clinical symptoms by active vaccination against itch

BACKGROUND

Insect bite hypersensitivity (IBH) is the most common seasonal pruritic allergic dermatitis of horses occurring upon insect bites. In recent years, a major role for IL-31 in allergic pruritus of humans, monkeys, dogs, and mice was acknowledged. Here, we investigate the role of IL-31 in IBH of horses and developed a therapeutic vaccine against equine IL-31 (eIL-31).

METHODS

IL-31 levels were quantified in allergen-stimulated peripheral blood mononuclear cells (PBMCs) and skin punch biopsies of IBH lesions and healthy skin from IBH-affected and healthy horses. The vaccine consisted of eIL-31 covalently coupled to a virus-like particle (VLP) derived from cucumber mosaic virus containing a tetanus toxoid universal T-cell epitope (CuMVTT). Eighteen IBH-affected horses were recruited and immunized with 300 μg of eIL-31-CuMVTT vaccine or placebo and IBH severity score was recorded.

RESULTS

IL-31 was increased in PBMCs and exclusively detectable in skin lesions of IBH-affected horses. Vaccination against eIL-31 reduced delta clinical scores when compared to previous untreated IBH season of the same horses and to placebo-treated horses in the same year. The vaccine was well tolerated without safety concerns throughout the study.

CONCLUSION

TH2-derived IL-31 is involved in IBH pathology and accordingly the immunotherapeutic vaccination approach targeting IL-31 alleviated clinical scores in affected horses.

Role of the Pruritic Cytokine IL-31 in Autoimmune Skin Diseases

Many autoimmune skin diseases, such as bullous pemphigoid (BP), psoriasis and certain types of chronic urticaria, are associated with intensive pruritus. While histamine and neuropeptides have previously been ascribed to play a role in itch that accompanies these diseases, recent evidence suggests that the pruritogenic cytokine interleukin (IL)-31 is a major driver of pruritic responses. IL-31 was originally shown to be produced by activated helper T cells, particularly Th2 cells, mast cells, macrophages and dendritic cells. However, more recent evidence demonstrated that eosinophils are a major source of this cytokine too, particularly in bullous pemphigoid. Basophils have also been shown to express the cytokine which, through autocrine action, strongly supports the production of other Th2-type cytokines from these cells. These investigations suggest that the dynamic recruitment of eosinophils and basophils in some autoimmune skin diseases could play an important role in the severity of IL-31-mediated itch. Furthermore, these studies suggest that IL-31, in addition to its pruritic actions, also has potential immunomodulatory roles in terms of supporting Th2-type immunity, which often underpins IgE-associated autoimmune diseases (such as bullous pemphigoid and urticaria) as well as allergies. While the role of IL-31 in psoriasis remains to be clarified, current evidence shows that this cytokine plays a major role in BP, chronic spontaneous urticaria and dermatomyositis. This suggests potential use of IL-31 receptor-blocking therapeutic approaches (e.g., Nemolizumab) for the treatment of IL-31-associated disorders.