High magnification microscope

The above dewaxed and rehydrated sections were put into a wet box, and an appropriate amount of Weigert ferrioxylamine A and B were mixed in equal amounts. The sections were stained with acidic ethanol differentiation solution for 5–10 min, with ammonia blue return for several seconds, with the fuchsin staining solution for 5–10 min, and washed with acetic acid working solution for 1 min. Then the sections were treated with phosphomolybdenum solution for 1–3 min, and Aniline blue solution for 1–2 min. The sections were dehydrated rapidly with 95% ethanol after acetic acid working solution, and with anhydrous ethanol for 3 times. After that, soak in xylene and add drops of neutral gum to seal tablets. Under a high-magnification microscope (Olympus, Japan) the LV collagen content was measured in five visual fields of each section, and four inconsecutive sections from each heart by using Image J software (National Institutes of Health, USA). The interstitial collagen volume fraction (CVF) was calculated as the ratio of the stained collagen area to the total myocardial area.

The colon tissues were fixed with 4% paraformaldehyde for 24 h. They were embedded in paraffin, cut into 3 μM sections, stained with hematoxylin-eosin, and the colon tissue injury was observed under a high-magnification microscope (Olympus, Japan). The histopathological score of the colon was evaluated under a blind condition. Briefly, the histopathological score of colonic lesions was evaluated based on the degree of inflammation, lesion depth, crypt structure, etc., (Supplementary Table S3). To detect the mucous thickness and mucin-secreting goblet cells number count, AB-PAS staining was performed. AB-PAS (G1285, solarbio) staining kits were applied to the sectioned tissue slides following the manufacturers’ recommended protocols.