Allium tuberosum alleviates pulmonary inflammation by inhibiting activation of innate lymphoid cells and modulating intestinal microbiota in asthmatic mice

Objective: This study tests whether long-term intake of Allium tuberosum (AT) can alleviate pulmonary inflammation in ovalbumin (OVA)-induced asthmatic mice and evaluates its effect on the intestinal microbiota and innate lymphoid cells (ILCs).

Methods: BALB/c mice were divided into three groups: phosphate buffer saline, OVA and OVA + AT. The asthmatic murine model was established by sensitization and challenge of OVA in the OVA and OVA + AT groups. AT was given to the OVA + AT group by oral gavage from day 0 to day 27. On day 28, mice were sacrificed. Histopathological evaluation of lung tissue was performed using hematoxylin and eosin, and periodic acid-Schiff staining. The levels of IgE in serum, interleukin-5 (IL-5) and IL-13 from bronchoalveolar lavage fluid (BALF) were measured by enzyme-linked immunosorbent assay. The ILCs from the lung and gut were detected by flow cytometry. 16S ribosomal DNA sequencing was used to analyze the differences in colon microbiota among treatment groups.

Results: We found that long-term intake of AT decreased the number of inflammatory cells from BALF, reduced the levels of IL-5 and IL-13 in BALF, and IgE level in serum, and rescued pulmonary histopathology with less mucus secretion in asthmatic mice. 16S ribosomal DNA sequencing results showed that AT strongly affected the colonic bacteria community structure in asthmatic mice, although it had no significant effect on the abundance and diversity of the microbiota. Ruminococcaceae and Desulfovibrionaceae were identified as two biomarkers of the treatment effect of AT. Moreover, AT decreased the numbers of ILCs in both the lung and gut of asthmatic mice.

Conclusion: The results indicate that AT inhibits pulmonary inflammation, possibly by impeding the activation of ILCs and adjusting the homeostasis of gut microbiota in asthmatic mice.