A 'brain-gut-skin axis focused' clinical perspective approach with intestinal microbiota analyzes in dogs with atopic dermatitis

Objective: Canine atopic dermatitis, which is among the inflammatory skin diseases occurring in dogs, is most commonly directed against environmental allergens and progresses with inflammatory and pruritic allergic skin involvement with characteristic clinical features associated with Immunoglobulin E antibodies. Numerous studies have shown that the development of allergic diseases such as asthma and atopic dermatitis is closely related to changes in gut microbial diversity and composition. The development of enteric diseases is often accompanied by signs of cutaneous lesions, meaning that the gut and skin can affect each other. Therefore, targeting gut microbial changes may be an alternative to regulate immune responses and improve cutaneous health in patients with atopic dermatitis. To better understand dysbiosis, it is important to follow the interaction between the skin and gut microbiome and shed light on new therapeutic approaches. The main goal of our study was to demonstrate that microbiota changes, as well as allergenic factors that cause atopic dermatitis, cause changes in dogs suffering from atopy and are directly related to the disease. Materials and Methods: The animal material of our study consisted of dogs of both sexes and of different ages, brought to the Small Animal Clinic of the Faculty of Veterinary Medicine, Aydın Adnan Menderes University, with a preliminary diagnosis of atopic dermatitis (itching, alopecia, crusting, dandruff, hyperpigmentation, etc.) anamnesis. Group I included dogs with atopic dermatitis in line with Favrot criteria (n=14), and Group II included 26 dogs, healthy dogs (without atopic dermatitis or any other disease) (n = 12). Detailed laboratory analyzes including epidermal corneometric analyzes were performed for the relevant diseases in the cases. IgE levels specific to 20 different allergens in dogs in all groups were determined by the in vitro Polycheck allergy test. Microbiota analyzes were carried out by storing the collected fecal samples under the necessary conditions and using the MiDOG® All-in-One Microbial Test with a new generation DNA sequencing test and outsourcing overseas services. Appropriate statistical methods were used to calculate and compare the obtained parameters. Results: In the results of microbiota composition based on phylum, it was seen that Bacteroidetes and Proteobacteria were higher in percentage terms in dogs with atopic dermatitis compared to the healthy group, and on the contrary, Firmicutes, Actinobacteria and Fusobacteria were higher in the healthy group compared to the group of dogs with atopic dermatitis. At family level, members of Actinomycetaceae, Corynebacteriaceae, Porphyromonadaceae, Streptococcaceae, Fusobacteriaceae, Campylobacteraceae, Enterobacteriaceae, Pseudomonadaceae families were numerically higher in animals with atopic dermatitis than in healthy animals, while Coriobacteriaceae, Clostridiaceae, Peptostreptococcaceae, Ruminococcaceae, Bacteroidaceae, Lachnospiraceae families were seen to be higher in healthy animals than in sick animals. Among the species most frequently seen in the species-based microbiome results of healthy animals were unidentified bacteria from the Fusobacteriales family, Peptoclostridium sp34341, Porphyromonas cangingivalis, Corynebacterium amycolatum and Corynebacterium jeikeium. Species seen in the species-based microbiome results of dogs with atopic dermatitis include Megamonas funiformis, unidentified bacteria from the Pseudomonadales and Fusobacteriales families, Corynebacterium amycolatum, Porphyromonas cangingivalis, Campylobacter helveticus, Corynebacterium lactis, Bacteroides plebeius, Prevotella copri, Fusobacterium mortiferum and Blautia hansenii was detected. Conclusion: Significant differences were found between the analyzed patients and the control group. The close relationship between microbiota analyzes and atopic dermatitis is promising for future treatment methods.