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JBLC Update - May 2018

Update on research into Canine Addisons – May 2018

In 2016 the JBLC was approached by Professor Catchpole to help with funding for a project into autoantibodies in Canine Addisons, to see whether they can be used as part of diagnostic testing and potentially to identify dogs that have an autoimmune reaction, before they develop clinical signs. Bearded Collies were to be one of the breeds focused on in this research.

Funding was also sought from the KC Charitable Trust who donated £25,000 to the project with the proviso that the remaining £5000 required was raised by the JBLC.

We decided to try and raise the funds by setting up a Justgiving page. Each of the six Bearded Collie Clubs made a donation resulting in £1000 to start the ball rolling and together with generous donations of £1000 each from the Pointer Club, Southern Finnish Lapphund Club and Standard Poodle Club, whose breeds were also included in the research, plus money from individual donors, we raised over £10,000.

The research commenced in late 2016, and members of the Beardie community and the other breeds, who owned dogs affected by Addisons, generously sent blood samples to Prof Catchpole for the project which was completed in late 2017.

In addition to the Addisons research Professor Catchpole provided a sample of DNA from an Addisonian Beardie for the KC/AHT Genome project. This, and the DNA from a healthy Bearded Collie, has been sequenced and the resulting data shared with Professor Catchpole for future research.

Unfortunately there was only one Bearded Collie of the 15 tested that demonstrated autoantibody reactivity against P450scc. It is possible that there are breed differences in which adrenal autoantigens drive the autoimmune response and these were not represented for this breed with the panel selected. It is possible that results of screening for autoantibodies against 21-OH, will yield more definitive results. Although this might appear a little disappointing, all knowledge is part of the bigger picture and further research can now be planned.

The JBLC are very grateful to the Clubs mentioned above and to all those individuals who donated money and/or blood samples for this research, their generosity will help to further our knowledge of this complex disease.

Professor Catchpole has kindly written a short summary of the work completed so far.

Serological profiling of Autoantibodies in Canine Hypoadrenocorticism

Brian Catchpole BVetMed MSc PhD FRVCS
Professor of Companion Animal Immunology

Lay Summary:

Canine Addison’s disease results from autoimmune destruction of the adrenal glands, leading to a deficiency in corticosteroid production. This results in a number of clinical signs, from waxing and waning non-specific illness to collapse and sudden death. In humans, the disease is associated with the presence of autoantibodies in the blood, which target the enzymes involved in steroid synthesis (known as P450scc, 21OH, 17OH and 3βHSD). We previously developed a radio- immunoassay for canine P450scc and demonstrated that a proportion of dogs affected with Addison’s disease were autoantibody positive. The aim of the project was 1) to adapt this assay to a non-radioactive format, 2) to expand the autoantigen panel for use in serological testing and 3) to specifically test serum samples from Bearded collies, a high risk breed for this disease.

1) We successfully cloned canine p450scc into a new vector and produced recombinant protein containing a nanoluciferase tag, for use in a luciferase immunoprecipitation assay. Serum samples from Addisonian dogs were tested and a proportion of dogs were shown to be positive, similar to that seen with the original radio-immunoassay.

2) We successfully cloned canine 17OH and 3βHSD, although the cloning of 21OH failed. We developed autoantibody assays for these two additional steroid synthesis enzymes and demonstrated that a proportion of Addisonian dogs were positive (10/58 positive for 17OH autoantibodies and 8/53 positive for 3βHSD autoantibodies). Repeat cloning of canine 21OH into a new vector has now been achieved and we will be testing this autoantigen in the luciferase immunoprecipitation assay in the future (with an undergraduate research student).

3) Serum samples from 15 Bearded collies were submitted to the Royal Veterinary College during the course of the project. These were tested for autoantibodies against P450scc, 17OH and 3βHSD. Only one dog was positive and reacted to P450scc only. It is possible that Bearded collies react to 21OH or some other (as yet unidentified) adrenal autoantigen.

Future plans:

We will continue the research into autoimmunity in Addison’s disease, using undergraduate research project students for small-scale projects. We have a student who is interested in taking on the 21OH immunoassay. We will continue to pursue different avenues for sponsorship (e.g. crowdfunding, charities and commercial sources, such as Dechra). The one year MRes programme is a cost effective way of advancing this research programme as well as providing a postgraduate training experience for a veterinary graduate.

Further details on the project and a copy of the academic abstract can be obtained
from the various Club JBLC representatives or the JBLC Secretary:

Mrs Y Fox, Peters Bank Cottage, Harperley, Stanley, Co. Durham, DH9 9TY
Tel:01207 290036, e mail: Y.Fox@bushbladesbeardies.co.uk

July 2018