Preferential gene transcription of T helper 2 cytokines in peripheral CCR4(+) CD4(+) lymphocytes in dogs

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.

Expression and functional analysis of chemokine receptor 7 in canine lymphoma cell lines

C-C chemokine receptor 7 (CCR7) contributes to cell homing to lymph nodes (LNs). Recent studies reported that CCR7 is also expressed in tumor cells, which correlates with LN metastasis in various cancers. However, the expression of CCR7 in tumor cells is unknown in dogs due to the lack of appropriate antibodies. In the present study, a fusion protein of C-C chemokine ligand 19 (CCL19) was employed as an alternative method to CCR7 antibodies. The fusion CCL19 protein specifically detected CCR7 expressed in canine lymphoma cell lines, which showed active chemotaxis to both canine and mouse ligands. The present study will help further research on the involvement of canine CCR7 in LN metastasis.

Serum canine thymus and activation-regulated chemokine (TARC/CCL17) concentrations correlate with disease severity and therapeutic responses in dogs with atopic dermatitis

Background

Thymus and activation‐regulated chemokine (TARC/CCL17) has been implicated in the pathogenesis of canine atopic dermatitis (cAD). Serum TARC concentrations are a reliable biomarker for human atopic dermatitis; however, their potential as a biomarker for cAD has not been investigated.

Hypothesis/Objectives

To investigate whether serum TARC concentrations correlate with disease severity and therapeutic responses for cAD.

Animals

Thirty‐nine dogs with cAD and 42 healthy dogs were recruited.

Methods and materials

Serum TARC concentrations in dogs with cAD and healthy dogs were measured by sandwich ELISA with anti‐canine TARC antibodies. The clinical severity of cAD was scored using the validated Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI‐04). Serum TARC concentrations were compared between dogs with cAD and healthy controls, and their relationship with CADESI‐04 was examined. Serum TARC concentrations also were measured in 20 dogs with cAD treated with prednisolone or oclacitinib for four weeks.

Results

Serum TARC concentrations were significantly higher in dogs with cAD than in healthy dogs (P < 0.001). In dogs with cAD, serum TARC concentrations correlated with CADESI‐04 scores (ρ = 0.457, P < 0.01). Furthermore, serum TARC concentrations significantly decreased in treated dogs with the attenuation of clinical signs (P < 0.001). Changes in serum TARC concentrations before and after treatment correlated with those in CADESI‐04 scores (ρ = 0.746, P < 0.001).

Conclusions and clinical relevance

Serum TARC concentrations have potential as a clinical and research tool for the objective evaluation of disease severity and therapeutic responses for cAD.

Foxp3+ Regulatory T Cells Associated With CCL17/CCR4 Expression in Carcinomas of Dogs

Regulatory T cells (Tregs) can be targeted in cancer immunotherapy. A previous study has shown that the chemokine CCL17 and the receptor CCR4 play a role in Treg recruitment in canine urothelial carcinoma. Here, we describe the association of tumor-infiltrating Tregs with CCL17/CCR4 expression in dogs with other carcinomas. In this study, we investigated 23 dogs with mammary carcinoma, 14 dogs with oral squamous cell carcinoma, 16 dogs with pulmonary adenocarcinoma, and 8 healthy control dogs. Immunohistochemistry showed that Foxp3⁺ Tregs and CCR4⁺ cells were increased in the tumor tissues of mammary carcinoma, squamous cell carcinoma, and pulmonary adenocarcinoma, when compared with the healthy tissues. The number of CCR4⁺ cells was associated with that of Foxp3⁺ Tregs. Double immunofluorescence labeling confirmed that most tumor-infiltrating Foxp3⁺ Tregs expressed CCR4. In vitro, canine carcinoma cell lines expressed CCL17 mRNA. Quantitative RT-PCR (reverse transcriptase-polymerase chain reaction) showed that CCL17 mRNA expression in canine carcinomas was increased approximately 10- to 25-fold relative to that of healthy tissues. These results suggest that the CCL17/CCR4 axis may drive Treg recruitment in a variety of canine carcinomas. CCR4 blockade may be a potential therapeutic option for tumor eradication through Treg depletion.

Phenotypic analysis of mice xenografted with canine epitheliotropic cutaneous T-cell lymphoma cells

BACKGROUND

In canine epitheliotropic cutaneous T-cell lymphoma (ECTCL), neoplastic cells cause skin lesions and potentially metastasize to lymph nodes, blood and other organs. Murine models are potentially valuable for elucidating the molecular mechanisms responsible for regulation of ECTCL cell migration.

HYPOTHESIS/OBJECTIVES

To describe a phenotype of mice xenografted with canine ECTCL cells (EO-1 cells).

ANIMALS

Four NOD.CB17-Prkdc^scid /J (NOD SCID) mice were used.

METHODS AND MATERIALS

EO-1 cells were subcutaneously xenografted into NOD SCID mice. After four weeks, the development of tumour lesions in skin and other organs was investigated.

RESULTS

Mice developed skin lesions with metastasis to the lymph nodes, spleen, lung, blood and liver.

CONCLUSIONS AND CLINICAL IMPORTANCE

Mice xenografted with EO-1 cells may be useful for studying the pathogenesis of canine ECTCL.