Although major advancements have made in investigating the aetiology of SLE (systemic lupus erythaematosus), the role of MDSCs (myeloid-derived suppressor cells) in SLE progression remains confused. Recently, some studies have revealed that MDSCs play an important role in lupus mice. However, the proportion and function of MDSCs in lupus mice and SLE patients are still poorly understood. In the present study, we investigated the proportion and function of MDSCs using different stages of MRL/lpr lupus mice and specimens from SLE patients with different activity. Results showed that splenic granulocytic (G-)MDSCs were significantly expanded by increasing the expression of CCR1 (CC chemokine receptor 1) in diseased MRL/lpr lupus mice and in high-disease-activity SLE patients. However, the proportion of monocytic (M-)MDSCs remains similar in MRL/lpr lupus mice and SLE patients. G-MDSCs produce high levels of ROS (reactive oxygen species) through increasing gp91^phox expression, and activated TLR2 (Toll-like receptor 2) and AIM2 (absent in melanoma 2) inflammasome in M-MDSCs lead to IL-1β (interleukin 1β) expression in diseased MRL/lpr mice and high-disease-activity SLE patients. Previous study has revealed that MDSCs could alter the plasticity of Th17 (T helper 17) cells and Tregs (regulatory T-cells) via ROS and IL-1β. Co-culture experiments showed that G-MDSCs impaired Treg differentiation via ROS and M-MDSCs promoted Th17 cell polarization by IL-1β in vitro. Furthermore, adoptive transfer or antibody depletion of MDSCs in MRL/lpr mice confirmed that MDSCs influenced the imbalance of Tregs and Th17 cells in vivo. Our results indicate that MDSCs with the capacity to regulate Th17 cell/Treg balance may be a critical pathogenic factor in SLE.

Dysbiosis of gut microbiota is a critical factor in the pathogenesis of asthma. Manipulating gut microbiota is a promising therapeutic intervention in asthma, and is being extensively studied. Gu-Ben-Fang-Xiao Decoction (GBFXD), derived from traditional Chinese medicine, is an effective and safe therapeutic formula for asthma in remission stage (ARS). Herein, we showed that GBFXD treatment remarkably alleviated ARS by improving respiratory function and lung histopathology. Asthmatic mice displayed a dysbiosis of gut microbiota, represented by significantly increased abundance of Bacteroidetes and decreased abundance of Firmicutes in gut, while GBFXD treatment reversed the gut dysbiosis in asthmatic mice at phylum, family, and genus levels. Moreover, our data showed that GBFXD treatment increased the abundance of short-chain fatty acid (SCFA)-producing bacteria in asthmatic mice, such as Firmicutes, Lachnospiraceae, and Bifidobacteriaceae, which consequently led to elevated levels of SCFAs. Furthermore, GBFXD treatment significantly enhanced the regulatory T cell differentiation via SCFAs, particularly acetate, in asthmatic mice. More critically, the protective effect of GBFXD was shown to be transmissible among asthmatic mice through co-housing microbiota transplantation. Antibiotic cocktail and acetate replenishment experiments also further substantiated the importance of SCFA-producing gut microbiota in GBFXD action. We, thus, demonstrated for the first time that gut microbiota dysbiosis existed in ARS. GBFXD could ameliorate ARS through the microbiota-acetate-Tregs axis.

Jiegeng Gancao decoction, which is composed of Jiegeng and Gancao at a weight ratio of 1:2, was widely used for treating pharyngalgia and cough for thousands of years. Our previous work indicated that Gancao could increase the systemic exposure of platycodin D and deapio-platycodin D, two main components in Jiegeng. However, whether Jiegeng could alter the pharmacokinetics of the main compounds in Gancao is still unknown. Thus, the purpose of this study was to compare the oral pharmacokinetics of flavonoids and saponins from Gancao alone vs. after co-administration with Jiegeng. Furthermore, Caco-2 cell transport and fecal hydrolysis were investigated to explain the altered pharmacokinetic properties. Pharmacokinetics results suggested that the bioavailability of liquiritin, isoliquiritin, glycyrrhizin and its metabolite, glycyrrhetinic acid, could be improved while bioavailability of liquiritigenin and isoliquiritigenin deteriorated when co-administered with Jiegeng. The Caco-2 transport study showed no significant difference of the P_app values of the main components in Jiegeng Gancao decoction when compared with those in Gancao decoction (p > 0.05). The in vitro metabolism study suggested that saponins and flavonoids glycosides in Gancao were influenced and the metabolic characteristics of most ingredients were consistent with pharmacokinetic results, such as liquiritin and glycyrrhetinic acid. The hydrolysis of liquiritigenin and glycyrrhizin observed with fecal lysate in vitro appeared consistent with the oral pharmacokinetics. Based on experiments, the pharmacokinetic profiles of six components in Gancao were influenced by Jiegeng. The metabolic process might partially contribute to the altered pharmacokinetic behavior. The metabolism of some components of Gancao appeared to be inhibited when coadministered with Jiegeng, possibly by the Jiegeng constituent platycodin.