Extensive Histopathological Characterization of Inflamed Bowel in the Dextran Sulfate Sodium Mouse Model with Emphasis on Clinically Relevant Biomarkers and Targets for Drug Development

Abstract

This study aims to develop a reliable and reproducible inflammatory bowel disease (IBD) murine model based on a careful spatial–temporal histological characterization. Secondary aims included extensive preclinical studies focused on the in situ expression of clinically relevant biomarkers and targets involved in IBD. C57BL/6 female mice were used to establish the IBD model. Colitis was induced by the oral administration of 2% Dextran Sulfate Sodium (DSS) for 5 days, followed by 2, 4 or 9 days of water. Histological analysis was performed by sectioning the whole colon into rings of 5 mm each. Immunohistochemical analyses were performed for molecular targets of interest for monitoring disease activity, treatment response and predicting outcome. Data reported here allowed us to develop an original scoring method useful as a tool for the histological assessment of preclinical models of DSS-induced IBD. Immunohistochemical data showed a significant increase in TNF-α, α4β7, VEGFRII, GR-1, CD25, CD3 and IL-12p40 expression in DSS mice if compared to controls. No difference was observed for IL-17, IL-23R, IL-36R or F480. Knowledge of the spatial–temporal pattern distribution of the pathological lesions of a well-characterized disease model lays the foundation for the study of the tissue expression of meaningful predictive biomarkers, thereby improving translational success rates of preclinical studies for a personalized management of IBD patients.

Induction of mastitis by cow-to-mouse fecal and milk microbiota transplantation causes microbiome dysbiosis and genomic functional perturbation in mice

“…Paraffin-embedded tissues were cut on a Leica Rotary Microtome (Leica Microsystems), placed onto SuperFrost Plus slides, and dried overnight at 37 °C. Sections were deparaffinized with xylene, and gradually rehydrated through graded alcohols for staining with standard hematoxylin and eosin (H & E staining) sectioned [ 70 ]. To assess the degree of tissue injury to the mammary gland and colon, we used the Chiu Scoring System [ 71 ] in a blinded manner, where the number of inflammatory cells was counted in 12 randomly selected fields from each slide at a magnification of 400× .…”

“…To assess the degree of tissue injury to the mammary gland and colon, we used the Chiu Scoring System [ 71 ] in a blinded manner, where the number of inflammatory cells was counted in 12 randomly selected fields from each slide at a magnification of 400× . The slides were observed for severe, diffuse interstitial and/or alveolar infiltrate of inflammatory cells, focal to multifocal areas of tissue damage, epithelial abnormalities and extensive necrotic areas in mastitic mice [ 70 ]. The degree of necrosis in mammary gland tissues was scored on a scale of 0–3 (normal 0, mild 1, moderate 2, severe 3).…”

“…The degree of necrosis in mammary gland tissues was scored on a scale of 0–3 (normal 0, mild 1, moderate 2, severe 3). The degree of colon injury was scored as grades 0 (normal mucosa), 1 (development of subepithelial spaces at villus tips), 2 (extension of the subepithelial space with moderate lifting of the epithelial layer), 3 (massive epithelial lifting with a few denuded villi), 4 (denuded villi with exposed capillaries), and 5 (disintegration of the lamina propria, ulceration, and hemorrhage) [ 66 , 70 ]. The slides were assessed under an Olympus BX51 upright microscope (40× objective), and finally images were collected using an Olympus DP73 camera through cellSens entry software (Olympus Corporation, Japan), and visualized using image J software ( https://imagej.nih.gov/ij/ ).…”

Inflammatory Bowel Disease-Associated Gut Commensals Degrade Components of the Extracellular Matrix

“…Colorimetric and fluorescent images were obtained on an inverted Leica DMi8 microscope. The H&E images were blinded prior to histopathological scoring, and we used the method described by Bonfiglio et al ( 87 ) to quantitatively describe the lamina propria cellularity, architectural damage, and epithelial abnormalities ( Table S5 ).…”

Inflammatory bowel disease-associated gut commensals degrade components of the extracellular matrix

“…They were also inspected for visible clinical signs of pathology. The presence of diarrhea, rectal bleeding, and weight lost were separately graded on a 0 to 3 scale (Supplementary Table 5) adapted from Gommeaux et al (74). The scores were then added to calculate the disease activity index (DAI).…”