Comparative immune responses against Psoroptes ovis in two cattle breeds with different susceptibility to mange

Abstract

The sheep scab mite, Psoroptes ovis, is a major problem in the beef cattle industry, especially in Belgian Blue (BB) cattle. This breed is naturally more predisposed to psoroptic mange but reasons for this high susceptibility remain unknown. Different immune responses could be a potential cause; thus in this study, the cutaneous immune response and in vitro cellular immune response after antigen re-stimulation were examined in naturally infested BB. Cytokine production in the skin and in circulating re-stimulated peripheral blood mononuclear cells (PBMC) demonstrated a mixed pro-inflammatory Th2/Th17 profile, with transcription of IL-4, IL-13, IL-6 and IL-17. Strong IL-17 up-regulation in the skin of BB was associated with an influx of eosinophils and other immune cells, potentially leading towards more severe symptoms. Virtually no changes in cutaneous IFN-γ transcription were detected, while there was substantial IFN-γ up-regulation in re-stimulated PBMC from infested and uninfested animals, potentially indicating a role of this pro-inflammatory cytokine in the innate immune response. In Holstein–Friesian (HF) cattle, generally more resistant to P. ovis infection, a largely similar immunologic response was observed. Differences between HF and BB were the lack of cutaneous IL-17 response in infested HF and low transcription levels of IFN-γ and high IL-10 transcription in re-stimulated PBMC from both infested and uninfested animals. Further research is needed to identify potential cell sources and biological functions for these cytokines and to fully unravel the basis of this different breed susceptibility to P. ovis.

Host immune responses to the itch mite, Sarcoptes scabiei, in humans

“…Recently our group reported that PBMC gamma delta (γδ) + T cells increased in mange infected pigs relative to controls from as early as one week post mite infestation with these increases sustained throughout the infestation [ 88 ]. Similarly, strong PBMC proliferation of γδ + T cells was reported in cattle infested with P. ovis [ 33 ]. These peripheral blood responses mirrored cutaneous responses, with skin cell infiltrates in the lesions of CS pigs showing significantly higher γδ + T cell numbers than those with OS [ 88 ].…”

“…In CS, skin biopsy sections from two patients have shown large numbers of eosinophils in the dermis [ 24 ] and 58% of a cohort of CS patients were reported to have peripheral eosinophilia [ 14 ]. In Psoroptes ovis infested sheep and cattle, lesional histology studies also show an eosinophil dominated immunoinflammatory infiltrate [ 32 , 33 ]. In addition, eosinophil infiltrations have been detected in the skin dermis of red foxes infested with S. scabiei [ 34 ].…”

“…PBMCs isolated from CS patients secreted increased levels of Th2 cytokines IL-4, IL-5 and IL-13, and decreased secretion of the Th1 cytokine IFN-γ as compared to OS upon stimulation with scabies mite antigens [ 35 ], similar to those seen with Der p 1 and HDM allergy [ 99 ]. Transcriptional analysis of skin biopsies from pigs with CS and cattle susceptible to severe psoroptic mange similarly revealed increased expression of IL-4, IL-5 and IL-13 [ 33 , 46 ]. IL-4 and IL-13 play important roles in class switching of B cells and induce co-expression of IgE and IgG4 [ 100 , 101 ], and thus the presence of these cytokines in CS is in alignment with the extremely high levels of IgG4 and IgE observed [ 14 ].…”

“…Studies have demonstrated increased TGF-β, IL-23 and IL-1β expression in immune response to scabies mite infestation [ 18 , 46 ], indicating that there are immune signals available in the local skin environment which may foster the generation of IL-17 secreting T cells. Furthermore, our group has shown increased IL-17 and IL-23 production in T cells isolated from skin lesions of pigs with CS [ 46 , 88 ] and high levels of IL-17 have also been documented in the skin lesions of cattle breeds susceptible to psoroptic mange but not in those breeds resistant to Psoroptes infestation [ 33 ]. IL-17 secretion further exacerbates the ongoing inflammatory responses by inducing expression of TNF-α, IL-1β and IL-6 in epithelial cells as well as keratinocytes and fibroblasts [ 103 ].…”

Decomposing variation in immune response in a wild rodent population

“…Individuals vary in their immune response. Within a population, some individuals may fail to make protective immune responses following either natural infection or vaccination and so are especially vulnerable to infectious disease 1–4 . Defining the patterns of such variability will enhance our ability to manage the health of individuals – especially those that are most susceptible to infectious disease in human, livestock or wildlife populations.…”