Chestnut Shell Tannins: Effects on Intestinal Inflammation and Dysbiosis in Zebrafish

Abstract

The aim of the present study was to test the possible ameliorative efficacy of phytochemicals such as tannins on intestinal inflammation and dysbiosis. The effect of a chestnut shell (Castanea sativa) extract (CSE) rich in polyphenols, mainly represented by tannins, on k-carrageenan-induced intestinal inflammation in adult zebrafish (Danio rerio) was tested in a feeding trial. Intestinal inflammation was induced by 0.1% k-carrageenan added to the diet for 10 days. CSE was administered for 10 days after k-carrageenan induced inflammation. The intestinal morphology and histopathology, cytokine expression, and microbiota were analyzed. The k-carrageenan treatment led to gut lumen expansion, reduction of intestinal folds, and increase of the goblet cells number, accompanied by the upregulation of pro-inflammatory factors (TNFα, COX2) and alteration in the number and ratio of taxonomic groups of bacteria. CSE counteracted the inflammatory status enhancing the growth of health helpful bacteria (Enterobacteriaceae and Pseudomonas), decreasing the pro-inflammatory factors, and activating the anti-inflammatory cytokine IL-10. In conclusion, CSE acted as a prebiotic on zebrafish gut microbiota, sustaining the use of tannins as food additives to ameliorate the intestinal inflammation. Our results may be relevant for both aquaculture and medical clinic fields.

Dietary Polyphenol, Gut Microbiota, and Health Benefits

“…Mango supplementation in mice fed with a high-fat diet can prevent the loss of beneficial intestinal bacteria, especially Bifidobacteria, Akkermansia, and Aldercrutzia [ 47 ]. Orso applied a diet of chestnut shell extract rich in tannin to a zebrafish intestinal inflammation model and found that it promoted the growth of healthy and beneficial bacteria ( Enterobacteriaceae and Pseudomonas ) [ 48 ]. Supplementation with polyphenols can also change the ratio of Firmicutes to Bacteroides .…”

Dietary Supplementation with a Blend of Hydrolyzable and Condensed Tannins Ameliorates Diet-Induced Intestinal Inflammation in Zebrafish (Danio rerio)

“…The histological analysis was achieved as described by Orso et al [21]. Specifically, intestine samples were fixed for 24 h at 4 • C in 4% formalin (pH 7.4) prepared in 0.01 M PBS (phosphate-buffered saline).…”

“…Dehydration in a series of increasing ethanol grades and clarification with xylene were performed prior to embedding tissues in paraffin. Embedded samples were cut with a microtome (Leica Microsystems, Wetzlar, Germany) into 5 µm sections, and, as reported by Orso et al [21], anatomically comparable sections of the mid-intestine were selected to be deparaffinized and stained with hematoxylin and eosin (H&E) or Alcian blue to perform morphological analyses and count of the number of goblet cells, respectively. A Leica DMI6000 light microscope equipped with a Leica DFC340 digital camera (Leica Microsystems, Wetzlar, Germany) was used to analyze the stained intestinal sections at 20X and 40X magnifications.…”

“…A Leica DMI6000 light microscope equipped with a Leica DFC340 digital camera (Leica Microsystems, Wetzlar, Germany) was used to analyze the stained intestinal sections at 20X and 40X magnifications. The score number was calculated by utilizing the score system proposed by Orso et al [21], and goblet cell quantification was performed as previously illustrated by Imperatore et al [32].…”

“…The migration of neutrophils to the affected areas and the production of proinflammatory cytokines take place before the effects are observed histologically (a reduction in villi and an increase in goblet cells) [19,20], shortening study times and giving considerable economic advantage. In a diet-induced intestinal inflammation zebrafish model, the increases in proinflammatory cytokines, neutrophil infiltration, goblet cells, and villi alteration with a loss of mucosal architecture were evident after a 10-day treatment with k-carrageenan [21].…”