Research Notes: A Poison Ivy Model and a Live Therapeutic Treatment
Safety Assessment
Mary Parker

Research Notes: A Poison Ivy Model and a Live Therapeutic Treatment

Breaking new ground in how to study a perennial summer problem, and using bacteria to treat a chronic GI problem. 

Mouse model validated for testing allergic reaction to poison ivy irritant

An inescapable fact of summer for many people around the world is the regrowth of poison ivy. The resin urushiol that is found in the leaves, stems, and roots of poison ivy and other related plants can cause allergic reactions in people and animals with a range of severity. Moreover, increasingly warmer global temperature is also contributing to widening the geographical location of poison ivy and related plants, further increasing the exposure risk.

Charles River recently collaborated with AstraZeneca in developing a mouse model for poison ivy-induced contact dermatitis. The findings were presented at the Federation of Clinical Immunology Societies (FOCIS) meeting in Boston last month. According to Charles River’s Dr. Harunor Rashid, one of the senior investigators involved in the work, there are very limited animal models available to the research community to study poison ivy-related skin conditions, which makes it difficult to test treatment options. Urushiol is a mixture of several closely related organic compounds, so Dr. Rashid and his colleagues had to first identify a reliable source in order to obtain reproducible results. They then used ear skin of the mice to test the urushiol-induced allergic reactions. Their experiments established an effective allergic contact dermatitis model, with redness and swelling observed on the areas of the ears exposed to urushiol.

The team also effectively used flow cytometry and gene analysis in the ear tissues to identify the pathways and cell types involved in the allergic reaction induced by urushiol. Of particular interest was the involvement of Th17-derived cytokines in the reaction, which may prove useful as a treatment target in the future.

Dr. Rashid and his colleagues will be publishing their results for the greater interest of the research community so that a concerted efforts could be made to better understand the underlying mechanisms and to find appropriate therapeutic options for this major public health hazard.

Charles River team tests effectiveness of bacteria against dysbiosis and E. coli

The common belief that bacteria is always bad for you is being challenged every day by new research. For people suffering from imbalances in their microbiome, or the community of bacterial species that lives inside us all, the importance of helpful bacteria to overall health is obvious.

A recent poster prepared in part by Charles River’s own Dominic Poulin and Rana Samadfam from InVivo Pharmacology in Senneville, and presented at the Federation of Clinical Immunology Societies (FOCIS) meeting in Boston last month, describes the effectiveness of bacterial treatments for dysbiosis mouse models. The mice were given dextran sulfate sodium (DSS) to mimic an ulcerative colitis-like condition, then were given various combinations of Lactobacillus bacteria species for a live theraeputic treatment regimen.

Dysbiosis is an umbrella term for various microbial imbalances in the body and has been associated with diseases like ulcerative colitis (UC). Typical digestive symptoms include bloody or soft feces, weight loss, and colonic inflammation. Australian company Servatus Biopharmaceuticals provided three Lactobacillus species as treatment options, which were administered to the model mice separately and in combination.

The results of the experiment showed the best outcomes in the mice treated with all three species at once. The treatment produced firmer and less bloody stool compared with each species alone. The relationship between each Lactobacillus species and pathogenic E. coli was also tested, leading to mixed results depending on the species of bacteria and strain of E. coli.

The research was also presented this month at the Chem International Conference on Immunity and Immunochemistry in San Francisco,