Immunoexpression of IL-33 in the different clinical aspects of canine atopic dermatitis.

Canine atopic dermatitis (CAD) is a chronic and inflammatory skin condition with a multifaceted origin, involving genetic factors, skin barrier abnormalities, immune responses, and hypersensitivity to various allergens. Interleukin 33 (IL-33), released by keratinocytes upon cellular injury, plays a crucial role in atopic dermatitis pathogenesis by inducing Th2 lymphocyte-mediated immune responses. This study aimed to evaluate IL-33 expression in dogs with atopic dermatitis and compare it to a control group. Forty-nine dogs were included, with 39 having atopic dermatitis, subdivided into groups based on clinical characteristics, and ten in the control group. Lesion and pruritus scores were assessed, and incisional biopsies were analyzed for dermatopathological characteristics. IL-33 expression was evaluated using immunohistochemistry, the analyses were blinded, based on the measurement of immunostaining areas using Image Pro-Plus software, version 4.5, relying on a semi-automatic color segmentation method, where the tissue immunostaining area for each biomarker was artificially delimited and quantified. Statistically significant differences in IL-33 immunostaining were found among groups (P=0.0005). Lichenified dogs (group 4) exhibited higher immunostaining compared to erythema (group 3) (P=0.0006), alesional pruritus (group 2) (P=0.0261), and the control group (group 1) (P=0.0079). IL-33 immunostaining increased with lesion progression, strongly correlating with lesion scores (P<0.0001), particularly in patients with chronic lesions characterized by erythema and lichenification. These findings suggest IL-33's significant role in canine atopic dermatitis pathogenesis and its association with lesion and inflammation scores during the chronic phase. This suggests potential therapeutic interventions targeting IL-33 or its receptors, though further studies are needed to explore these possibilities.

Bacterial microbiota and proinflammatory cytokines in the anal sacs of treated and untreated atopic dogs: Comparison with a healthy control group.

The pathogenesis of anal sacculitis has not been extensively investigated, although atopic dogs seem to be predisposed to the disease. The aim of this study was therefore to characterize and compare the bacterial microbiota and pro-inflammatory cytokines in the anal sacs of dogs from three groups (healthy dogs, untreated atopic dogs and atopic dogs receiving antipruritic treatment or allergen-specific immunotherapy) in order to determine whether changes could be at the origin of anal sacculitis in atopic dogs. Bacterial populations of anal sac secretions from fifteen healthy dogs, fourteen untreated and six treated atopic dogs were characterized by sequencing the V4 region of the 16S rRNA gene using Illumina technology. Proinflammatory cytokines were analyzed with the Luminex multiplex test. Community membership and structure were significantly different between the anal sacs of healthy and untreated atopic dogs (P = 0.002 and P = 0.003, respectively) and between those of untreated and treated atopic dogs (P = 0.012 and P = 0.017, respectively). However, the community structure was similar in healthy and treated atopic dogs (P = 0.332). Among the proinflammatory cytokines assessed, there was no significant difference between groups, except for interleukin 8 which was higher in the anal sacs of untreated atopic dogs compared to treated atopic dogs (P = 0.02), and tumor necrosis factor-alpha which was lower in the anal sacs of healthy dogs compared to treated atopic dogs (P = 0.04). These results reveal a dysbiosis in the anal sacs of atopic dogs, which may partially explain the predisposition of atopic dogs to develop bacterial anal sacculitis. Treatments received by atopic dogs (oclacitinib, desloratadine and allergen-specific immunotherapy) shift the microbiota of the anal sacs towards that of healthy dogs. Further studies are required to identify significant cytokines contributing to anal sacculitis in atopic dogs.

PDE4D and miR-203 are promising biomarkers for canine atopic dermatitis.

BACKGROUND: Canine atopic dermatitis (CAD) is a common genetically predisposed, inflammatory, and pruritic skin disorder that affects dogs globally. To date, there are no specific biomarkers available to diagnose CAD, and the current diagnosis is based on a combination of criteria including patient history, clinical signs, and exclusion of other relevant differential diagnoses. METHODS AND RESULTS: We examined the gene expression of phosphodiesterase 4D (PDE4D) in peripheral blood mononuclear cells (PBMCs), as well as miR-203 and miR-483 in plasma, in three groups: healthy dogs, CAD dogs, and other inflammatory pruritic skin diseases (OIPSD) such as pemphigus foliaceus, scabies, cutaneous lymphoma, and dermatophytosis. Our results showed that PDE4D gene expression in the CAD group is statistically higher compared to those in the healthy and OIPSD groups, suggesting PDE4D may be a specific marker for CAD. Nevertheless, no correlation was found between PDE4D gene expression levels and the lesion severity gauged by CAD severity index-4 (CADESI-4). We also showed that miR-203 is a generic marker for clinical dermatitis and differentiates both CAD and OIPSD inflammatory conditions from healthy controls. CONCLUSIONS: We show that PDE4D is a potential marker to differentiate CAD from non-atopic healthy and OIPSD while miR-203 may be a potential marker for general dermatologic inflammation. Future study of PDE4D and miR-203 on a larger scale is warranted.

Investigation of the relationship between atopic dermatitis of dogs and intestinal epithelial damage.

BACKGROUND: A significant association between atopic dermatitis and leaky gut syndrome has been demonstrated in humans. No studies have been conducted to determine whether there is an association between atopic dermatitis and intestinal damage in dogs. OBJECTIVES: This study aimed to determine whether there is an association between canine atopic dermatitis and intestinal damage using selected intestinal-related biomarkers. METHODS: Twenty-six dogs with atopic dermatitis and 10 healthy dogs were included. Moderate-to-severe pruritus, erythema, erosion and alopecia on different parts of the body were sought in dogs to suspect atopic dermatitis. The presence of atopic dermatitis was confirmed by an allergic skin test. Serum biomarkers including intestinal fatty acid binding protein (I-FABP), intestinal alkaline phosphatase (IAP), trefoil factor-3 (TFF-3), immunoglobulin E (IgE), interleukin-4 (IL-4) and interleukin-13 (IL-13) concentrations were measured from venous blood samples. RESULTS: Of the 26 dogs tested for allergens, 16 were found to be sensitive to mould mites, 10 to vernal grass, eight to house dust mites, five to wheat dust and five to grass pollen mix allergens. Significant increases in serum IAP, TFF-3, IgE, IL-4 and IL-13 concentrations were determined. CONCLUSION: It was thought that the increase in TFF-3 and IAP concentrations may be due to the presence of intestinal epithelial damage and the repair of this damage. In addition, the development of atopic dermatitis may be predisposed to the entry of allergens into the body through sites of intestinal damage.

Establishment of clinical criteria for the diagnosis of adverse food reactions in dogs with atopic dermatitis.

BACKGROUND: Diagnosis of canine adverse food reactions (AFRs) is based on vague criteria, such as '>50% improvement' during elimination diet trial (EDT) followed by 'deterioration' during provocation test (PT). OBJECTIVE: The objective of the study was to use predefined criteria to evaluate response during EDT [i.e., Owner Global Assessment of Treatment Efficacy (OGATE) = good-to-excellent] and relapse during PT [i.e., Owner Global Assessment of Challenge Deterioration (OGACD) = moderate-to-severe and/or >100% increase of lesional (Canine Atopic Dermatitis Extent and Severity Index, 4th iteration, CADESI-04) and/or of pruritus (pruritus Visual Analog Scale, PVAS) scores]. ANIMALS: Twenty-nine dogs with atopic dermatitis. MATERIALS AND METHODS: An extensively hydrolysed diet was fed to all dogs followed, in seven of 11 nonresponders, by a second home-made novel-protein EDT. Dogs responding to either EDT were challenged with their previous diet. RESULTS: Thirteen (44.8%) dogs were diagnosed with AFRs: at the end of EDT, their OGATE was good (9 of 13; 69.2%) or excellent (four of 13; 30.8%), and both CADESI-04 (46.7%) and PVAS (71.1%) had decreased significantly; at the end of PT, OGACD was moderate or severe in 12 of 13 (92.3%) dogs, and both CADESI-04 (127.9%) and PVAS (181.8%) had increased significantly. Of the 16 dogs without AFRs, 6 (37.5%) responded to the commercial (n = 5) or home-made (n = 1) diet [OGATE = good (three of six) or excellent (three of six)], with significant concurrent reduction of CADESI-04 and nonsignificant reduction of PVAS, yet they did not relapse during PT. CONCLUSIONS AND CLINICAL RELEVANCE: The proposed (predefined) criteria for the evaluation of response during EDT and deterioration during PT seem reliable and are easily applicable in clinical practice and research.

A randomized double-blind clinical trial: Comparison of oclacitinib with a traditional Chinese herbal medicine product (Dihuang Guiqin capsule) in the treatment of canine atopic dermatitis.

Canine atopic dermatitis (cAD) is a common chronic inflammatory skin disease, which seriously affects the quality of life for both dogs and their owners. Currently, the common therapeutic drugs in the clinic have disadvantages such as obvious adverse effects and high prices. Traditional Chinese herbal medicine (TCHM) has great potential for the treatment of cAD. The aim of this study is to compare the effects of different doses of the TCHM product (Dihuang Guiqin capsule) and oclacitinib in the treatment of cAD through a randomized, double-blind trial. Sixty dogs diagnosed with AD were randomly and evenly divided into four groups (n = 15). The TCHM treatment group consisted of three subgroups that received three different oral doses (20, 40, and 60 mg/kg BW), while the control group received 0.5 mg/kg BW of oclacitinib. Each group was administered twice daily for 14 consecutive days. The results showed that both TCHM and oclacitinib significantly improved cAD-induced itching (evaluated by pVAS) and skin lesions (evaluated by CADESI-04), while interleukin 31 (IL-31) concentrations decreased significantly (P < 0.05) and serum biochemical indicators returned to normal. In particular, The therapeutic effects of TCHM medium- and high-dose groups were similar to those of oclacitinib (P > 0.05). The preliminary recommended dose of Dihuang Guiqin capsule for the treatment of cAD has been determined to be 40-60 mg/kg BW twice daily for 14 consecutive days, which can be reduced to once daily as appropriate. Dihuang Guiqin capsule was safe and well tolerated, which may be a new option for the treatment of cAD.

A placebo-controlled, double-blind study evaluating the effect of orally administered polyunsaturated fatty acids on the oclacitinib dose for atopic dogs.

BACKGROUND: Supplementation of polyunsaturated fatty acids (PUFA) enables dose reduction of prednisolone and ciclosporin in canine atopic dermatitis (cAD). OBJECTIVE: To determine if oral administration of PUFA reduces the dose of oclacitinib in cAD. ANIMALS: Twenty-two client-owned dogs with cAD receiving oclacitinib. MATERIALS AND METHODS: Dogs received a fish oil product (PUFA) or paraffin oil (placebo) for 16 weeks. Owners adjusted the oclacitinib dose according to daily pruritus assessments. On Day (D)0, D56 and D112, Canine Atopic Dermatitis Extent and Severity Index, fourth iteration (CADESI-04), pruritus Visual Analog Scale (PVAS), quality-of-life score (QoL), Global Assessment (GA), quality-of-coat (QoC) and adverse events were recorded. RESULTS: Mean daily oclacitinib dose was significantly reduced in the PUFA group from 0.51 ± 0.20 mg/kg/24 h (D0) to 0.19 ± 0.14 mg/kg/24 h (D85-112; p < 0.00001) and not in the placebo group (D0: 0.70 ± 0.33 mg/kg/24 h; D85-112: 0.53 ± 0.35 mg/kg/24 h, p = 0.5422). CADESI-04 did not change over time or differ between groups. PVAS was significantly lower in the PUFA group (2.8 ± 1.5) compared to placebo (4.2 ± 1.6) at D112 (p = 0.0375). QoL and QoC improved only in the PUFA group (QoL: D0: 20 ± 7, D112: 12 ± 5, p = 0.0057; QoC: D0: 0 ± 0.5, D112: 1 ± 0.5, p = 0.0410). GA on D112 was higher in the PUFA group (p = 0.008). No adverse events were observed. CONCLUSION: Oral supplementation of PUFA allowed dose reduction of oclacitinib and improved PVAS, QoL, QoC and GA. The use of PUFA is recommended and was safe in the atopic study dogs receiving oclacitinib.

Preliminary evaluation of a commercial shampoo and fine bubble bathing in the treatment of canine atopic dermatitis: A single-blinded, randomised, controlled study.

BACKGROUND: Fine bubble (FB) bathing has shown benefits on a mouse model of atopic dermatitis (AD). However, its efficacy in dogs with AD remains to be evaluated. OBJECTIVE: This study aimed to assess the clinical effectiveness of FB bathing in dogs with AD. ANIMALS: Seventeen dogs with AD whose clinical presentation showed a Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) score of <40. MATERIALS AND METHODS: The dogs were randomly assigned to either the FB bathing group or the shampoo group. The treatments were administered once a week as per the instructions, in a trial totalling 4 weeks. Evaluations were conducted on Day (D)0 and D28 to assess the outcomes of the trial. The severity of AD was measured using the CADESI-04 and the pruritus Visual Analog Scale (PVAS). The skin barrier function parameters, transepidermal water loss (TEWL) and stratum corneum hydration were measured before and after the treatment. RESULTS: Both treatment groups demonstrated a decreasing trend in CADESI-04 scores, yet the FB group exhibited significant improvement in comparison to the shampoo group after 1 month of trial. There were no significant changes in PVAS scores in either group. No significant difference was found in skin barrier function parameters between the two treatments, although TEWL slightly decreased in the FB group and slightly increased in the shampoo group after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: These results suggested that FB treatment provides benefits for dogs with AD and offers an alternative topical treatment option with a lesser impact on skin barrier function compared to frequent shampooing.

Effect of clothianidin exposure at the no-observed-adverse-effect level (NOAEL) in a mouse model of atopic dermatitis.

The effects of exposure to clothianidin (CLO), a neonicotinoid pesticide (NN), on the thymus and intestinal microbiota were recently revealed. Immune cells express nicotinic acetylcholine receptors (nAChRs), an NN target, suggesting CLO may disrupt the immune system. However, the relationship between CLO and atopic dermatitis (AD) is unknown. We administered a no-adverse-effect-level (NOAEL) dose of CLO to male NC/Nga mice with induced AD and measured, at three time points, key AD symptom indicators: epidermal thickening, mast cell number, total plasma IgE, and histamine levels. CLO increased total plasma IgE levels but reduced epidermal thickening, mast cell number, and plasma histamine levels in the early stages of AD. This demonstrates for the first time that CLO exposure inhibits AD's early symptoms.

Comparison of intradermal and serum testing for environmental allergen-specific immunoglobulin E determination in a laboratory colony of cats with naturally acquired atopic syndrome.

BACKGROUND: Allergen testing is used to select antigens included in the desensitisation vaccine. Intradermal skin test (IDT) is the gold standard in cats, yet allergen-specific immunoglobulin (Ig)E serological testing (ASIS) is often used. Feline data are lacking regarding the agreement between IDT and ASIS results. HYPOTHESIS/OBJECTIVES: The first objective of the study was to establish a colony of cats with naturally acquired feline atopic syndrome (FAS). Further objectives were to define their hypersensitivity disorder to detail the allergen tests results, and to assess similarity between the allergen tests. ANIMALS: Thirty-five cats with FAS and 10 control cats. MATERIALS AND METHODS: Enrolled cats went through a five phase-screening and quarantine process before joining the colony. An elimination diet trial was performed on all FAS cats. ASIS and IDT were consecutively performed on all cats under sedation. RESULTS: Reactions to 34 allergens were compiled for the 45 cats. Global sensitivity and specificity of ASIS were 34.7% and 78.9%, respectively. Only flea (ICC = 0.26, p = 0.040) and Dermatophagoides pteronyssinus (ICC = 0.48, p < 0.001) allergens had a significant intraclass correlation (weak agreement). Two FAS cats had negative tests including one cat with a concomitant food allergy. CONCLUSIONS AND CLINICAL RELEVANCE: This study depicts the first reported colony of cats with naturally acquired FAS. This is the first feline study to compare and show the poor agreement between allergen tests with a panel of 34 allergens. This colony also harbours two cats with FAS with negative allergen tests. These may represent the first described cats with an intrinsic form of atopic syndrome.

Update on the role of genetic factors, environmental factors and allergens in canine atopic dermatitis.

BACKGROUND: Canine atopic dermatitis (cAD) is a common, complex and multifactorial disease involving, among others, genetic predisposition, environmental factors and allergic sensitisation. OBJECTIVE: This review summarises the current evidence on the role of genetic and environmental factors and allergic sensitisation in the pathogenesis of cAD since the last review by ICADA in 2015. MATERIALS AND METHODS: Online citation databases and proceedings from international meetings on genetic factors, environmental factors and allergens relevant to cAD that had been published between 2015 and 2022 were reviewed. RESULTS: Despite intensive research efforts, the detailed genetic background predisposing to cAD and the effect of a wide range of environmental factors still need more clarification. Genome-wide association studies and investigations on genetic biomarkers, such as microRNAs, have provided some new information. Environmental factors appear to play a major role. Lifestyle, especially during puppyhood, appears to have an important impact on the developing immune system. Factors such as growing up in a rural environment, large size of family, contact with other animals, and a nonprocessed meat-based diet may reduce the risk for subsequent development of cAD. It appears that Toxocara canis infection may have a protective effect against Dermatophagoides farinae-induced cAD. House dust mites (D. farinae and D. pteronyssinus) remain the most common allergen group to which atopic dogs react. Currently, the major allergens related to D. farinae in dogs include Der f 2, Der f 15, Der f 18 and Zen 1. CONCLUSIONS AND CLINICAL RELEVANCE: Canine atopic dermatitis remains a complex, genetically heterogeneous disease that is influenced by multiple environmental factors. Further, well-designed studies are necessary to shed more light on the role of genetics, environmental factors and major allergens in the pathogenesis of cAD.

A randomised, double-blinded trial to assess the effect of oclacitinib and prednisolone on intradermal allergen and prick tests in dogs with atopic dermatitis.

BACKGROUND: Intradermal (IDT) and prick (PT) tests are used to select allergens for allergen-specific immunotherapy in dogs with atopic dermatitis (cAD). However, the use of antipruritic drugs before performing these tests may influence the results. OBJECTIVE: To evaluate the influence of the drugs oclacitinib and prednisolone on the immediate-phase reactions of IDT and PT. ANIMALS: Thirty client-owned dogs with cAD with positive reactions to at least one allergen extract on IDT or PT. MATERIALS AND METHODS: Dogs were randomly assigned to receive oclacitinib 0.4-0.58 mg/kg per os, every 12 h (n = 14), or prednisolone 0.37-0.65 mg/kg p.o., every 12 h (n = 16) for 14 days. IDT and PT were performed on Day (D)0 before treatment and on D14. RESULTS: At D14 there was no significant reduction in the means of the orthogonal diameters of the positive immediate-phase reactions of the IDT (p = 0.064) in the oclacitinib group; however, in the PT, the diameter of the positive reactions reduced significantly (p = 0.048). In both tests, there was no significant reduction in the total number of positive reactions (IDT, p > 0.999; PT, p = 0.735). In the prednisolone group, the means of the orthogonal diameters of positive immediate-phase reactions were significantly reduced in both tests (IDT, p = 0.001; PT, p ≤ 0.001) and there also was a reduction in the total number of positive reactions (IDT, p = 0.022; PT, p = 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: The use of oclacitinib 0.4-0.58 mg/kg twice daily for 14 days does not interfere with IDT results in dogs with cAD. However, oclacitinib may reduce PT reactivity. The use of prednisolone 0.37-0.65 mg/kg twice daily results in a reduction in both IDT and PT results.

Update on the skin barrier, cutaneous microbiome and host defence peptides in canine atopic dermatitis.

BACKGROUND: Canine atopic dermatitis (AD) is a complex inflammatory skin disease associated with cutaneous microbiome, immunological and skin barrier alterations. This review summarises the current evidence on skin barrier defects and on cutaneous microbiome dysfunction in canine AD. OBJECTIVE: To this aim, online citation databases, abstracts and proceedings from international meetings on skin barrier and cutaneous microbiome published between 2015 and 2023 were reviewed. RESULTS: Since the last update on the pathogenesis of canine AD, published by the International Committee on Allergic Diseases of Animals in 2015, 49 articles have been published on skin barrier function, cutaneous/aural innate immunity and the cutaneous/aural microbiome in atopic dogs. Skin barrier dysfunction and cutaneous microbial dysbiosis are essential players in the pathogenesis of canine AD. It is still unclear if such alterations are primary or secondary to cutaneous inflammation, although some evidence supports their primary involvement in the pathogenesis of canine AD. CONCLUSION AND CLINICAL RELEVANCE: Although many studies have been published since 2015, the understanding of the cutaneous host-microbe interaction is still unclear, as is the role that cutaneous dysbiosis plays in the development and/or worsening of canine AD. More studies are needed aiming to design new therapeutic approaches to restore the skin barrier, to increase and optimise the cutaneous natural defences, and to rebalance the cutaneous microbiome.

Open trial of recombinant Der f 2 pullulan-conjugated immunotherapy in cats.

BACKGROUND: Allermmune HDM (Zenoaq) is a recombinant Dermatophagoides farinae 2 (Der f 2) pullulan-based immunotherapy vaccine whose efficacy on house dust mite allergic dogs has been demonstrated. There is no published information on its use in cats. OBJECTIVES: The objective of the study was to evaluate the safety and short-term effects of Allermmune HDM in Dermatophagoides farinae (Df)-sensitised cats. MATERIALS AND METHODS: Eleven cats diagnosed with atopic skin syndrome received Allermmune weekly for six weeks then monthly for three months (total duration 18 weeks). On Weeks 0, 6 and 18 clinical lesions were assessed by the Feline Dermatitis Extent and Severity Index (FEDESI); owners assessed pruritus with a 10-cm Visual Analog Scale (pVAS). Concurrent medication use was recorded. The allergen-specific immunoglobulin (Ig)E were measured before study inclusion with a commercial serological assay. RESULTS: There were no evident adverse effects. FEDESI and pVAS improved significantly after six weeks (p = 0.001 and p = 0.01, respectively). The pretreatment Df-specific IgE levels were significantly higher in the cats with improved clinical scores than in the cats with no clinical score change (p = 0.009). CONCLUSIONS AND CLINICAL RELEVANCE: Allermmune HDM may be safe in cats and has the potential to alleviate signs of atopic skin syndrome. Allergen-specific IgE levels may represent an efficacy marker. Controlled studies of longer duration and larger sample size are worth pursuing.

Are images worth a thousand words? A preliminary study testing a video for owner education in canine atopic dermatitis.

BACKGROUND: Successful management of canine atopic dermatitis (cAD) is challenging and effective pet owner education is crucial to successful outcomes. However, there are limited proven educational strategies in this area. Our goal was to create an effective and engaging educational tool for owners of dogs with cAD. HYPOTHESIS: Video-based education efficacy would be comparable to traditional verbal delivery. Secondary objectives included assessing client perception of the intervention, and determining if there were clinical benefits for the dogs and improved client adherence to treatment. SUBJECTS: Twenty-nine dogs with cAD and their owners were recruited from a teaching hospital of a European veterinary medicine faculty. MATERIALS AND METHODS: In this 8 week, prospective, randomised controlled study, clients in the control group (CG, n = 13) received verbal education and those in the intervention group (IG, n = 16) watched a video. Client knowledge was assessed at Day (D)0 and D56. Treatment adherence and perceived utility and appeal ratings were measured at D56. Clinical progress was assessed at D0 and D56 using CADESI-04 and PVAS10. RESULTS: The differences found in the means of cAD knowledge score, clinical outcomes, utility and appeal ratings and owners' adherence score between groups were not statistically significant. A significant association between the outcome and the intervention group concerning education success [CG, six of 13 (46.15%); IG, 15 of 16 (93.75%)] was found (p = 0.01). CONCLUSIONS AND CLINICAL RELEVANCE: Video-based instructions positively impacted owners' education and demonstrated their potential as a valuable tool. The authors believe that video-based education could be a time-efficient alternative for initial cAD education in veterinary clinics.

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.

Tumour necrosis factor-α induces C-C motif chemokine ligand 5 production in canine keratinocytes.

BACKGROUND: C-C motif chemokine ligand (CCL)5 induces skin inflammation in healthy dogs. In addition, CCL5 is overexpressed in the skin of experimental models of canine atopic dermatitis (cAD). Tumour necrosis factor (TNF)-α has been shown to be upregulated in cAD. However, it remains unclear whether TNF-α induces CCL5 production in canine keratinocytes. HYPOTHESIS/OBJECTIVES: To determine the effect of TNF-α on CCL5 production in canine keratinocyte culture and investigate possible synergy with interferon (IFN)-γ and interleukin (IL)-4. MATERIALS AND METHODS: CCL5 protein concentrations were measured by enzyme-linked immunosorbent assay (ELISA) in the culture supernatant of a cell line of canine progenitor epidermal keratinocyte (CPEK) cells stimulated with TNF-α with or without inhibitors of the TNF receptor signalling pathway. CCL5 protein concentrations also were measured in CPEK cells stimulated with TNF-α in the absence or presence of IFN-γ, a T-helper (Th)1-type cytokine, and/or IL-4, a Th2-type cytokine. RESULTS: TNF-α increased CCL5 production in CPEK cells in time- and dose-dependent manners. Inhibitors of the TNF receptor signalling pathway diminished CCL5 production. Although neither IFN-γ nor IL-4 alone induced CCL5 production in CPEK cells, the combination of TNF-α and IFN-γ, and not IL-4, synergistically enhanced CCL5 production in these cells. CONCLUSIONS AND CLINICAL RELEVANCE: TNF-α may be involved in skin inflammation in dogs by promoting CCL5 production in keratinocytes. Furthermore, the synergistic effect of TNF-α and IFN-γ suggests that the local Th1-type milieu may aggravate skin inflammation. Further studies are required to elucidate the role of TNF-α-induced CCL5 production of keratinocytes in the pathogenesis of cAD.

Interleukin-31 in serum and cerebrospinal fluid of dogs with syringomyelia.

BACKGROUND: Syringomyelia is a spinal cord cavity containing cerebrospinal fluid (CSF)-like fluid. If syringomyelia asymmetrically involves the dorsal horn grey matter of the spinal cord, affected dogs show increased signs of dysesthesia and neuropathic pain, like increased itching behaviour. In the dorsal horn, amongst others, receptors for Interleukin-31 (IL-31) can be found. IL-31 is one of the main cytokines involved in the pathogenesis of pruritus in atopic dermatitis in different species. This study investigates suspected elevated levels of IL-31 in serum and CSF of dogs showing signs of pain or increased itching behaviour related to syringomyelia. The IL-31 were measured in archived samples (52 serum and 35 CSF samples) of dogs with syringomyelia (n = 48), atopic dermatitis (n = 3) and of healthy control dogs (n = 11) using a competitive canine IL-31 ELISA. RESULTS: Mean serum IL-31 level in dogs with syringomyelia was 150.1 pg/ml (n = 39), in dogs with atopic dermatitis 228.3 pg/ml (n = 3) and in healthy dogs 80.7 pg/ml (n = 10). Mean CSF IL-31 value was 146.3 pg/ml (n = 27) in dogs with syringomyelia and 186.2 pg/ml (n = 8) in healthy dogs. Individual patients with syringomyelia (especially dogs with otitis media or otitis media and interna or intervertebral disc herniation) showed high IL-31 levels in serum and CSF samples, but the difference was not statistically significant. IL-31 serum and CSF levels did not differ significantly in dogs with syringomyelia with or without itching behaviour and with or without signs of pain. CONCLUSION: Based on this study, increased IL-31 levels seem not to be correlated with itching behaviour or signs of pain in dogs with syringomyelia, but might be caused by other underlying diseases.