Salivary Mucocele in a Laboratory Beagle

The histologic characteristics of a salivary mucocele in a beagle used in a toxicity study are described in this report. A pale yellowish cyst under the mandibular skin containing frothy mucus was observed at necropsy. Microscopically, numerous villous projections arose from the internal surface of the cyst and were lined by stratified epithelial-like macrophages, which were immunopositive for macrophage scavenger receptor A. A ruptured sublingual interlobar duct connected to the lumen was observed near the cyst. Luminal amorphous material showed a positive reaction with Alcian blue and periodic acid-Schiff staining as did mucin in the sublingual gland. Ultrastructurally, the epithelial-like macrophages had numerous vacuoles containing electron-lucent material, which was presumed to be lysosomal in origin, and had pseudopods on their cell surfaces interdigitating with those on the adjacent cells. This case report helps to understand the diversity of the background findings in beagles used in toxicity studies

Polygenic architecture informs potential vulnerability to drug-induced liver injury

Drug-Induced-Liver-Injury (DILI) is a leading cause of termination in drug development programs and removal of drugs from the market, and this is partially due to the inability to identify patients who are at risk1. Here, we developed a polygenic risk score (PRS) for DILI by aggregating effects of numerous genome-wide loci identified from previous large-scale genome-wide association studies (GWAS)2. The PRS predicted the susceptibility to DILI in patients treated with fasiglifam, amoxicillin-clavulanate or flucloxacillin, and in primary hepatocytes and stem cell-derived organoids from multiple donors treated with over 10 different drugs. Pathway analysis highlighted processes previously implicated in DILI, including unfolded protein responses and oxidative stress. In silico screening identified compounds that elicit transcriptomic signatures present in hepatocytes from individuals with elevated PRS, supporting mechanistic links and suggesting a novel screen for safety of new drug candidates. This genetic-, cellular-, organoid- and human-scale evidence underscored the polygenic architecture underlying DILI vulnerability at the level of hepatocytes, thus facilitating future mechanistic studies. Moreover, the proposed “polygenicity-in-a-dish” strategy might potentially inform designs of safer, more efficient, and robust clinical trials