Allergic asthma is a disease caused by allergens entering the respiratory tract, stimulating B lymphocytes to produce specific antibodies (mainly IgE) and stimulating mast cells, basophils and other immune cells to release inflammatory mediators.

In recent years, many epidemiological studies have shown that the incidence of asthma is related to diet. A high-fat, low fiber diet increases the risk of asthma. In addition, providing a diet rich in fruits and vegetables to patients with clinical asthma can alleviate their respiratory symptoms. However, the specific mechanism of this beneficial clinical outcome is unclear. In order to further explore the role of cellulose in the development of asthma, we established an asthma mouse model and gave high fiber diet to intervene.

Experimental method

Thirty C57 mice were divided into routine group (n), asthma group (as) and high fiber diet group (HF). The conventional diet contained 5% cellulose, and the high fiber diet contained 30% cellulose. The increase of cellulose content was achieved by reducing the content of corn starch. After that, the lung inflammation of mice was detected by ELISA and h&e staining, and the changes of intestinal flora and short chain fatty acids in feces were detected.

Experimental results and discussion

Pathological sections of the lung showed that in group n, the wall and smooth muscle of the bronchioles were thin, there were no foreign bodies in the cavities and alveoli, and there were no obvious inflammatory cell infiltration around the bronchi or vascular walls. In as group, the wall of small bronchus was thickened, the wall of blood vessels was thickened, smooth muscle proliferated, lumen was narrowed, and there were a large number of eosinophils and lymphocytes infiltrating around bronchus and blood vessels. The pulmonary interstitium and alveolar cavity were filled with exudates, and the alveolar space was widened. Compared with as group, HF group had relatively complete airway epithelial structure, 

he degree of inflammatory cell infiltration around bronchus and blood vessels was significantly reduced, and the exudates in pulmonary interstitium and alveolar cavity were also significantly reduced.

The levels of IL-4 and IgE in as group were significantly higher than those in N group (p<0.05, p<0.05), but the levels of IL-4 and IgE in HF group were significantly lower than those in as group (p<0.01, 0<0.05)

This study shows that a high fiber diet can reduce lung inflammation and asthma symptoms in asthmatic mice. This result may not be caused by the increase of intestinal short chain fatty acids (SCFA), but by regulating the composition of intestinal flora to regulate the body's lipid metabolism, so as to participate in the inflammatory response of remote organs.