Biology subjects

McQuade, R. M.

Publications and source records attributed to McQuade, R. M..

2 recordsLinked to original sources

bioRxiv2025

Probing the activity of cysteine cathepsins in inflammatory bowel diseases

Cathepsin S is a cysteine protease that has been implicated in inflammatory bowel diseases (IBD) for its ability to promote visceral pain. Given its pro-inflammatory roles, we hypothesized that cathepsin S would drive other symptoms associated with IBD. Using activity-based probes, we investigated cysteine cathepsin activation in human and murine colitis. We observed a significant increase in fecal cathepsin S in patients with ulcerative colitis compared to healthy controls, while cathepsin S in mucosal biopsies was unchanged. Mice with experimental colitis exhibited a modest increase in mucosal activity of both cathepsin S and X compared to naive mice. Luminal secretion of cathepsin S was dramatically increased upon colitis induction, although differences between mouse colonies were observed. To investigate the contribution of cathepsin S and cathepsin X to colitis, we induced colitis in cathepsin-deficient mice. Cathepsin X-deficient mice exhibited no clear differences in disease indicators compared to wild-type mice. While cathepsin S-deficient mice exhibited less rectal bleeding, less splenomegaly and marginally improved histological scores, weight loss, diarrhea, colon shortening, and myeloperoxidase activity were not significantly different from wild-type mice. To determine whether pharmacologic inhibition of cathepsin S activity would ameliorate symptoms of colitis, a reversible inhibitor LY3000328 was administered to mice at the initiation of colitis. LY3000328 provoked a clear upregulation of cathepsin S and L activity in the mucosa, most likely through a compensatory mechanism. This increase in protease activity was associated with exacerbated histological scores and splenomegaly. Collectively, these results suggest that cathepsin S, but not cathepsin X, may contribute to some of the symptoms of experimental colitis. While cathepsin S has potential to be a therapeutic target in colitis, improved strategies to sustain its inhibition are required in future.

pathology↗

bioRxiv2024

Gut Analysis Toolbox: Automating quantitative analysis of enteric neurons

The enteric nervous system (ENS) plays an important role in coordinating gut function. The ENS consists of an extensive network of neurons and glial cells within the wall of the gastrointestinal tract. Alterations in neuronal distribution, function, and type are strongly associated with enteric neuropathies and gastrointestinal (GI) dysfunction and can serve as biomarkers for disease. However, current methods for assessing neuronal counts and distribution suffer from undersampling. This is partly due to challenges associated with imaging and analyzing large tissue areas, and operator bias due to manual analysis. Here, we present the Gut Analysis Toolbox (GAT), an image analysis tool designed for characterization of enteric neurons and their neurochemical coding using 2D images of GI wholemount preparations. GAT is developed for the Fiji distribution of ImageJ. It has a user-friendly interface and offers rapid and accurate cell segmentation. Custom deep learning (DL) based cell segmentation models were developed using StarDist. GAT also includes a ganglion segmentation model which was developed using deepImageJ. In addition, GAT allows importing of segmentation generated by other software. DL models have been trained using ZeroCostDL4Mic on diverse datasets sourced from different laboratories. This captures the variability associated with differences in animal species, image acquisition parameters, and sample preparation across research groups. We demonstrate the robustness of the cell segmentation DL models by comparing them against the state-of-the-art cell segmentation software, Cellpose. To quantify neuronal distribution GAT applies proximal neighbor-based spatial analysis. We demonstrate how the proximal neighbor analysis can reveal differences in cellular distribution across gut regions using a published dataset. In summary, GAT provides an easy-to-use toolbox to streamline routine image analysis tasks in ENS research. GAT enhances throughput allowing unbiased analysis of larger tissue areas, multiple neuronal markers and numerous samples rapidly.

neuroscience↗