Parkinson's disease (PD) is associated with both locomotor deficits and gastrointestinal dysfunction, including microbiota dysbiosis and intestinal inflammation. This study investigates the effects of BBr60, a novel strain of high-purity therapeutic Bifidobacterium breve, on intestinal microbiota dysbiosis, intestinal inflammation, and neuroinflammation in PD mice. In animal experiments, we established an in vivo mouse model of Parkinson's disease using 6-hydroxydopamine (6-OHDA) and administered BBr60, along with NLRP3 agonists and inhibitors, via gavage. Behavioral testing was conducted to assess locomotor activity in mice. The 16S rRNA assay was employed to characterize the intestinal microbiota, while gas chromatography-mass spectrometry (GC-MS) was utilized to analyze short-chain fatty acids (SCFA). In cellular experiments, SCFA mixtures formulated according to the SCFA profile observed in animal experiments were administered to RAW264.7 macrophages together with NLRP3 agonists and inhibitors. Western blot (WB) and immunofluorescence (IF) techniques were used for the detection of relevant biomarkers. We found significant microbiota dysbiosis and an imbalance in NLRP3/NLRP6 inflammasomes in the intestine of PD mice. Treatment with BBr60 improved locomotor activity, alleviated microbiota dysbiosis, and increased SCFA in the intestine. BBr60 also restored the NLRP3/NLRP6 balance and inhibited macrophage M1-type polarization in the intestinal environment. Furthermore, SCFAs have been demonstrated to inhibit lipopolysaccharide (LPS)-induced M1-type polarization of macrophages by restoring the balance between NLRP3 and NLRP6 in RAW264.7 macrophages. However, this inhibitory effect was diminished in the presence of an NLRP3 activator. Similarly, the activator of NLRP3 also abrogated the ameliorating effect of BBr60 in intestinal inflammation and neuroinflammation of PD mice. In summary, these findings underscore the pivotal role of the NLRP3/NLRP6 inflammasome and SCFA-mediated signaling in macrophage polarization and intestinal homeostasis. BBr60 may be a promising therapeutic candidate for PD, by ameliorating pathological changes in the intestine.
