Experimental Stroke Induces Chronic Gut Dysbiosis and Neuroinflammation in Male Mice

Abstract

Recent literature implicates gut epithelia mucosa and intestinal microbiota as important players in post-stroke morbidity and mortality. As most studies have focused on the acute effects of stroke on gut dysbiosis, our study objective was to measure chronic, longitudinal changes in the gut microbiota and intestinal pathology following ischemic stroke. We hypothesized that mice with experimental ischemic stroke would exhibit chronic gut dysbiosis and intestinal pathology up to 36 days post-stroke compared to sham controls. Male C57BL/6J mice were subjected to 60 minutes of transient middle cerebral artery occlusion (tMCAO) or sham surgery. To determine the long-term effects of tMCAO on gut dysbiosis, fecal boli were collected pre- and post-tMCAO on days 0, 3, 14, and 28. Bioinformatics analysis demonstrate significant differences in abundance among Firmicutes and Bacteroidetes taxa at the phylum, family, and species levels in tMCAO compared to sham mice that persisted up to one month post-stroke. The most persistent changes in post-stroke microbial abundance were a decrease in bacteria family S24-7 and significant increases in Ruminococcaceae. Overall, these changes resulted in a persistently increased Firmicutes:Bacteroidetes ratio in stroke animals. Intestinal histopathology showed evidence of chronic intestinal inflammation that included marked increases in immune cell infiltration with mild-moderate epithelial hyperplasia and villous blunting. Increased astrocyte and microglial activity were also detected one-month post-stroke. These results demonstrate that acute, post-stroke disruption of the gut-brain-microbiota axis progresses to chronic gut dysbiosis, intestinal inflammation, and chronic neuroinflammation.Clinical PerspectivesThe microbiota-gut-brain axis, recently implicated in several neurological disorders, remains largely unexplored at chronic time points post-tMCAO.Our results demonstrate chronic gut dysbiosis, prolonged behavioral deficits, and persistent cerebral and intestinal inflammation post-tMCAO in male C57BL/6J mice.These results suggest that manipulation of microbiota may help reduce poor outcomes after stroke and lead to improved post-stroke functional recovery.

Novel Role of Ghrelin Receptor in Gut Dysbiosis and Experimental Colitis in Aging

“…Our data also showed that the aged group had a higher Firmicutes/Bacteroidetes ratio (F/B ratio) as expected (Figure 1C), which is in support of inflamm-aging. Interestingly, aged GHS-R KO mice showed a significantly increased F/B ratio, which is in line with the microbiome profiles observed in diseases such as obesity, hypertension, and stroke [46][47][48]. Higher F/B ratio in the microbiota of aged GHS-R KO suggests that GHS-R ablation modifies the microbiota toward a disease-susceptible state.…”

Lactulose Improves Neurological Outcomes by Repressing Harmful Bacteria and Regulating Inflammatory Reactions in Mice After Stroke

“…Compared with the PTS_TDW group, lactulose supplementation decreased the abundance of proinflammatory taxa (Gao et al, 2018;Ma et al, 2018) such as Desulfovibrio, Helicobacter, and Turicibacter, which might partially explain the decrease in a-diversity after drug administration [The relative abundance genus csv file and the heatmap of clustering for genus abundance and are in Supplemental Material and Supplemental Figure 4)]. In addition, the ratio of Firmicutes to Bacteroidetes, which is seen as a marker of dysbiosis in some studies, was decreased in the PTS_TDW group compared with the HC group (the average F/B ratios of the HC, PTS_TDW and PTS_LAC groups were 1.186,0.331 and 0.460 respectively; the relative abundance phylum csv file and the heatmap of clustering for phylum abundance are shown in the Supplemental Material and Supplemental Figure 5), while another study found that the Firmicutes to Bacteroidetes ratio increased after stroke (Brichacek et al, 2020); therefore, we speculated that an altered Firmicutes to Bacteroidetes ratio indicated gut dysbiosis.…”

Cerebral ischaemic stroke results in altered mucosal IgA responses and host-commensal microbiota interactions

“…Alterations in gastrointestinal function and commensal microbiota composition following stroke are well described both in patients (Cui et al, 2023; Xia et al, 2019; Xu et al, 2019; Yamashiro et al, 2017; Yin et al, 2015) and animal models (Benakis et al, 2016; Brichacek et al, 2020; Houlden et al, 2016; Singh et al, 2016; Stanley et al, 2016; Stanley et al, 2018). Importantly, changes in microbial communities correlate with worsened stroke outcome and secondary complications (Benakis et al, 2016; Brichacek et al, 2020; Singh et al, 2016; Stanley et al, 2016; Tuz et al, 2022; Xia et al, 2019). Indeed, antibiotic intervention post-stroke can lead to improved outcomes (Benakis et al, 2020b; Liu et al, 2022).…”

“…Increasing evidence suggests that stroke also results in rapid changes in the composition of the gastrointestinal microbiota in both mice and humans (Houlden et al, 2016;Singh et al, 2016;Stanley et al, 2018), which is associated with increased mortality and worsened neurological function (Sun et al, 2021;Xia et al, 2019;. In experimental models of stroke in rodents, changes to the commensal microbiota are also associated with alterations in intestinal motility and loss of barrier integrity (Benakis and Liesz, 2022;Benakis et al, 2020a;Brichacek et al, 2020;Crapser et al, 2016;Delgado Jimenez and Benakis, 2021;Diaz-Marugan et al, 2023;Durgan et al, 2019;Houlden et al, 2016;Singh et al, 2016;Stanley et al, 2016;Stanley et al, 2018). Despite these observations, the underlying factors that drive loss of intestinal function and modulation of the microbiota following stroke remain poorly understood.…”