Dermal immune responses against Psoroptes ovis in two cattle breeds and effects of anti-inflammatory dexamethasone treatment on the development of psoroptic mange

Zhenzhen Chen,Mathilde Pas,Koen Chiers,Peter Geldhof,Stijn Casaert,Bart Pardon,Nathalie De Wilde,Luc Duchateau,Edwin Claerebout,Wouter Van Mol

doi:10.1186/s13567-020-00874-x

Abstract

Psoroptic mange is a common disease of livestock, caused by Psoroptes ovis. Compared to Holstein–Friesian (HF) cattle, the Belgian Blue (BB) cattle breed is highly susceptible to the infestation. However, the mechanism for this difference is still unclear. To determine the factors responsible for this breed susceptibility, the immune response to P. ovis was studied in experimentally infested BB and HF cattle, using clinical signs, histology, immunohistochemical profiling and gene expression analysis of skin biopsies. The mite numbers and lesion area of BB cattle were greater than in HF during the whole study period. Significant influxes of eosinophils in the epidermis and dermis were detected in comparison with the pre-infestation samples in both breeds, with significantly higher eosinophils in BB at 6 weeks post infestation (wpi). Mast cell numbers were unaffected at all stages of infestation in HF, but were significantly elevated relative to pre-infestation in BB cattle at 2 and 6 wpi. The more pronounced cutaneous eosinophilia and higher IL-4 levels at 6 wpi in BB cattle suggest that a Th2-type immune response is underlying the higher susceptibility of the BB breed. In naturally infested BB cattle, development of the psoroptic mange lesions and eosinophils and CD3+ T cell areas were severely depressed after anti-inflammatory treatment with dexamethasone. Together, these results suggest that a stronger Th2-type immune response to P. ovis causes the skin lesions in psoroptic mange in BB cattle and that local anti-inflammatory treatment could potentially be an alternative to control the pathology caused by this parasite.

Highlights

Psoroptic mange is a severe disease, which reduces animal welfare and causes financial losses due to performance loss and treatment costs, especially in the sheep and in the beef industry [1,2,3]
Lesion development and immune response in artificially infested cattle Before infestation, no skin lesions were observed in the Belgian Blue (BB) and HF cattle
P. ovis infestation was associated with significantly increased transcription of several cytokines and genes related to skin pathology, including interleukin (IL)-4, IL-5, IL-6, IL-8, IL-10, IL-13, IFN-γ, loricrin and filaggrin

Summary

Introduction

Psoroptic mange is a severe disease, which reduces animal welfare and causes financial losses due to performance loss and treatment costs, especially in the sheep and in the beef industry [1,2,3]. A rapid growth phase sets in with a sharp increase in mite numbers and active lesions that are mainly found at the withers, back and the tail base, but can eventually cover most of the body [3, 12,13,14] During this process, pruritus becomes more intense due to the host allergic reaction to the mites, leading to self-trauma behaviour, such as licking and rubbing. These actions will make the affected animals comfortable to some degree, mechanical skin abrasion can cause hair loss, skin damage and bleeding wounds [13,14,15] All these factors will intensify the local intradermal inflammation, which leads to increased serum extravasation, creating the perfect microclimate for mites to survive. Natural recovery in Holstein Friesian (HF) cattle is more frequent compared to Belgian Blue (BB) cattle [13]

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