Fig. 3.

Reduction of SARS-CoV-2 membrane glycoprotein-induced IL-6 secretion and PDE4B expression by butyric acid produced by mycelium fermentation of L. rhamnosus EH8. (A) HPLC chromatographs with milli-absorbance units (mAU) of the butyric acid in media containing mycelium (FM), L. rhamnosus EH8 (L.r) or L. rhamnosus EH8 plus mycelium (L.r+FM) were displayed. Different concentrations of butyric acid were applied onto HPLC to establish a standard curve (STD). (B) The concentrations of butyric acid were quantified based on the height (mAU) of STD. J774 macrophage cell lines (10⁵ cells/well) in 12-well cell culture plates were treated with butyric acid or H₂O for 10 min before addition of SARS-CoV-2 membrane glycoprotein for 12 h. (C) The mRNA expression of PDE4B and (D) secretion of IL-6 were quantified by RT PCR and ELISA, respectively. Results are the mean ± SD obtained from three separate experiments. *p < 0.05. **p < 0.01 (two-tailed t-test).