Phenotyping of lumbosacral stenosis in Labrador retrievers using computed tomography.

Deep phenotyping tools for characterizing preclinical morphological conditions are important for supporting genetic research studies. Objectives of this retrospective, cross-sectional, methods comparison study were to describe and compare qualitative and quantitative deep phenotypic characteristics of lumbosacral stenosis in Labrador retrievers using computed tomography (CT). Lumbosacral CT scans and medical records were retrieved from data archives at three veterinary hospitals. Using previously published qualitative CT diagnostic criteria, a board-certified veterinary radiologist assigned dogs as either lumbosacral stenosis positive or lumbosacral stenosis negative at six vertebral locations. A second observer independently measured vertebral canal area, vertebral fat area, and vertebral body area; and calculated ratios of vertebral canal area/vertebral body area and vertebral fat area/vertebral body area (fat area ratio) at all six locations. Twenty-five dogs were sampled (lumbosacral stenosis negative, 11 dogs; lumbosacral stenosis positive, 14 dogs). Of the six locations, cranial L6 was the most affected by lumbosacral stenosis (33%). Five of six dogs (83%) with clinical signs of lumbosacral pain were lumbosacral stenosis positive at two or more levels. All four quantitative variables were significantly smaller at the cranial aspects of the L6 and L7 vertebral foramina than at the caudal aspects (P < 0.0001). Fat area ratio was a significant predictor of lumbosacral stenosis positive status at all six locations with cranial L6 having the greatest predictive value (R2 = 0.43) and range of predictive probability (25-90%). Findings from the current study supported the use of CT as a deep phenotyping tool for future research studies of lumbosacral stenosis in Labrador retrievers.

Association of MHC region SNPs with irritant susceptibility in healthcare workers.

Irritant contact dermatitis is the most common work-related skin disease, especially affecting workers in "wet-work" occupations. This study was conducted to investigate the association between single nucleotide polymorphisms (SNPs) within the major histocompatibility complex (MHC) and skin irritant response in a group of healthcare workers. 585 volunteer healthcare workers were genotyped for MHC SNPs and patch tested with three different irritants: sodium lauryl sulfate (SLS), sodium hydroxide (NaOH) and benzalkonium chloride (BKC). Genotyping was performed using Illumina Goldengate MHC panels. A number of SNPs within the MHC Class I (OR2B3, TRIM31, TRIM10, TRIM40 and IER3), Class II (HLA-DPA1, HLA-DPB1) and Class III (C2) genes were associated (p < 0.001) with skin response to tested irritants in different genetic models. Linkage disequilibrium patterns and functional annotations identified two SNPs in the TRIM40 (rs1573298) and HLA-DPB1 (rs9277554) genes, with a potential impact on gene regulation. In addition, SNPs in PSMB9 (rs10046277 and ITPR3 (rs499384) were associated with hand dermatitis. The results are of interest as they demonstrate that genetic variations in inflammation-related genes within the MHC can influence chemical-induced skin irritation and may explain the connection between inflamed skin and propensity to subsequent allergic contact sensitization.

Genetic Basis of Irritant Susceptibility in Health Care Workers.

OBJECTIVE: The aim of this study was to investigate the association of single nucleotide polymorphisms (SNPs) within genes involved in inflammation, skin barrier integrity, signaling/pattern recognition, and antioxidant defense with irritant susceptibility in a group of health care workers. METHODS: The 536 volunteer subjects were genotyped for selected SNPs and patch tested with three model irritants: sodium lauryl sulfate (SLS), sodium hydroxide (NaOH), and benzalkonium chloride (BKC). Genotyping was performed on genomic DNA using Illumina Goldengate custom panels. RESULTS: The ACACB (rs2268387, rs16934132, rs2284685), NTRK2 (rs10868231), NTRK3 (rs1347424), IL22 (rs1179251), PLAU (rs2227564), EGFR (rs6593202), and FGF2 (rs308439) SNPs showed an association with skin response to tested irritants in different genetic models (all at P < 0.001). Functional annotations identified two SNPs in PLAU (rs2227564) and ACACB (rs2284685) genes with a potential impact on gene regulation. In addition, EGF (rs10029654), EGFR (rs12718939), CXCL12 (rs197452), and VCAM1 (rs3917018) genes showed an association with hand dermatitis (P < 0.005). CONCLUSIONS: The results demonstrate that genetic variations in genes related to inflammation and skin homeostasis can influence responses to irritants and may explain inter-individual variation in the development of subsequent contact dermatitis.

Evaluation of a lymph node proliferation assay for its ability to detect pharmaceuticals with potential to cause immune-mediated drug reactions.

Hypersensitivity reactions to systemically administered drugs cannot be predicted using available preclinical models. This research is a collaborative project to evaluate the ability of the Lymph Node Proliferation Assay (LNPA) to predict systemic hypersensitivity caused by pharmaceuticals. The assay design is a modification of the Local Lymph Node Assay with the major modification being injection of the test substance subcutaneously to achieve a known systemic exposure to the drug. Fourteen compounds were evaluated in the LNPA. These were two clinically negative drugs (Metformin, phenobarbital), an assay positive control (streptozotocin), eight human hypersensitivity positive drugs (sulfamethoxazole, procainamide, clonidine, ofloxacin, nevirapine, abacavir, lamotrigine, zomepirac), and 3 investigational drugs (CM40874, CM40954 and CM40420), one of which caused hypersensitivity in primates. Hypersensitivity-positive drugs were classified as such based on at least two of three independent data sources: U.S. FDA postmarketing database, drug labeling information, and clinical trial data. All drugs were tested in multiple laboratories for a total of 2-12 evaluations per compound. The pure drug substance was used for testing if it could be obtained commercially, otherwise the marketed drug formulation was used. Neither of the negative control drugs showed a positive reaction in the test system. Four of the eight hypersensitivity positive drugs showed a mixed or positive reaction. Two of the three investigational compounds gave a positive response. A smaller number of LNPAs were run concurrently using footpad injection and evaluation of the popliteal lymph node and gave generally comparable results. Additional development may increase the reproducibility of the assay and facilitate detection of drugs that require metabolic activation to become allergenic, or drugs for which there is dose-limiting toxicity. The data suggest that this method might be useful as a first-line screen to identify candidate drugs that are more likely to cause a high prevalence of human drug hypersensitivity.