Deprivation of Dietary Fiber Enhances Susceptibility of Piglets to Lung Immune Stress.

Yi Yang,Xuemei Jiang,Wentao Li,De Wu,Xuelin Cai,Lianqiang Che,Lijia Zhang,Yan Lin,Zhengfeng Fang,Jian Li,Bin Feng,Xilun Zhao,Shengyu Xu,Yong Zhuo

doi:10.3389/fnut.2022.827509

Abstract

Growing evidence suggests that dietary fiber enhances short-chain fatty acid (SCFA) producing gut microbes, improving lung immunity against invading pathogens via the gut–lung axis. This study investigated the effects of dietary fiber on lung immune stress after challenge with complete Freund's adjuvant (CFA) containing killed Mycobacterium tuberculosis. Thirty-six healthy hybrid Duroc, Landrace, and Yorkshire male piglets (9.7 ± 1.07 kg, 35 ± 3 days) were randomly fed a low fiber (LF) diet formulated with semipurified corn starch, soy protein concentrate, and fishmeal or a high fiber (HF) diet composed of 1,000 g LF diet plus 20 g inulin, and 100 g cellulose. Piglets were housed individually in the metabolism cages with eighteen replicates per group, with one pig per cage. All the piglets received similar levels of digestible energy and lysine and had similar weight gain. After dietary treatment for 28 days, nine piglets per group were intravenously administered CFA (0.4 mg/kg) or an equivalent amount of sterile saline in a 2 × 2 factorial arrangement. In piglets fed the LF diet, CFA caused lung damage and elevated serum C-reactive protein and relative mRNA expression of genes related to lung inflammation (NLRP3, Casp1, ASC, IL1β, IL18, Bax). Compared with the LF diet, the HF diet increased bacterial diversity and Deferribacteres (p = 0.01) in the phylum level and unidentified_Ruminococcaceae (p = 0.03) and Catenisphaera (p < 0.01) in the genus level. The HF diet improved increased short-chain fatty acids in feces, blood, cecal, and colonic digesta; reduced lung damage; and promoted lung recovery. Overall, dietary fiber deprivation enhanced the risk of piglets to lung immune stress, demonstrating the importance of dietary fiber in gut–lung health.

Highlights

Asthma is a chronic inflammatory disease of the airway, and more than 300 million people worldwide are threatened by this disease [1]
Throughout the experiment, there were no significant differences in body weight (BW), average daily feed intake (ADFI) or digestible energy, and lysine intake between piglets fed the high fiber (HF) and low fiber (LF) diets
Regardless of complete Freund’s adjuvant (CFA) treatment, piglets fed the HF diet had significantly higher concentrations of acetate, propionate, and butyrate in their caecal digesta and colonic digesta compared to piglets fed the LF diet (Table 4, p < 0.01)

Summary

Introduction

Asthma is a chronic inflammatory disease of the airway, and more than 300 million people worldwide are threatened by this disease [1]. Numerous studies suggest that the intestinal microbiota is a link between respiratory diseases and the immune system, and many recent studies. The treatment of intestinal diseases is known to prevent lung diseases, such as asthma, adult respiratory distress syndrome, and chronic obstructive pulmonary disease (COPD) [13,14,15]. Improvements in lung health are closely related to the treatment of intestinal disorders, such as colitis, irritable bowel syndrome, inflammatory bowel disease, and others [16, 17]. Together, these studies demonstrate that gut–lung communication plays a role in the control of overall health

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