The Cutaneous Microbiota & Cytokine Profile in Feline Allergic Dermatitis
Abstract
Feline atopic syndrome (FAS) is an allergic dermatological disease affecting cats, which has an unclear pathogenesis and clinical signs that are unique from atopic dermatitis affecting other species. Two factors thought to contribute to the disease are the microbial communities inhabiting the skin and immune dysfunction.
To address the involvement of the microbiota, the skin and oral microbiota on healthy animals was evaluated to understand what could be considered “normal”. The influence of two potentially important factors, breed and environment, on the bacterial and fungal microbiota was analyzed. Environment had little to almost no impact on the skin microbiota, with differences between indoor and outdoor cats only observed in the oral cavity. Breed also had little influence, although more so than environment, which indicates this factor may be worth taking into consideration for future studies.
With the understanding breed could have an influence on the cutaneous microbial communities, the sample cohort for the second study comparing healthy and allergic feline skin was restricted to mostly domestic short-haired cats. Due to their notorious role in allergic dermatoses, staphylococcal communities on feline skin were evaluated. Species-level characterization demonstrated that feline cutaneous staphylococcal populations are diverse, with several species of substantial relative abundance identified. S. epidermidis was the most prevalent species identified from healthy samples, while S. capitis was the most prominent in allergic samples.
Finally, cutaneous and systemic immune dysfunction in allergic cats and non-affected controls was evaluated, with the hypothesis that allergic individuals would have an immune system that favored a Th2-skewed response. Immunohistochemistry targeting IL-31, an important molecule in pruritus signaling in dogs and people, and RNAscope targeting IL-31 and other Th2-associated molecules was performed on skin biopsies. Serum samples were subjected to a multiplex panel covering 19 Th1- and Th2-associated molecules and an IL-31 enzyme-linked immunosorbent assay (ELISA). One target involved in IL-31 signaling, OSMR-β was found to have higher mRNA expression in the skin of affected cats relative to controls.
The results of this research indicate the pathomechanisms behind feline allergic dermatitis may include microbial and immune involvement. The specific immune profiles and cutaneous microbiota of allergic individuals is still unclear, however these results suggest species-level staphylococcal and OSMR signaling may be worth further investigating.
Citation
Older, Caitlin Elizabeth (2020). The Cutaneous Microbiota & Cytokine Profile in Feline Allergic Dermatitis. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /192488.