Preventive Effects of Bacillus licheniformis on Heat Stroke in Rats by Sustaining Intestinal Barrier Function and Modulating Gut Microbiota

Abstract

Heat stroke (HS) models in rats are associated with severe intestinal injury, which is often considered as the key event at the onset of HS. Probiotics can regulate the gut microbiota by inhibiting the colonization of harmful bacteria and promoting the proliferation of beneficial bacteria. Here, we investigated the preventive effects of a probiotic Bacillus licheniformis strain (BL, CMCC 63516) on HS rats as well as its effects on intestinal barrier function and gut microbiota. All rats were randomly divided into four groups: control (Con) + PBS (pre-administration with 1 ml PBS twice a day for 7 days, without HS induction), Con + BL group (pre-administration with 1 ml 1 × 108 CFU/ml BL twice a day for 7 days, without HS induction), HS + PBS (PBS, with HS induction), and HS + BL (BL, with HS induction). Before the study, the BL strain was identified by genomic DNA analysis. Experimental HS was induced by placing rats in a hot and humid chamber for 60 min until meeting the diagnostic criterion of HS onset. Body weight, core body temperature, survival rate, biochemical markers, inflammatory cytokines, and histopathology were investigated to evaluate the preventive effects of BL on HS. D-Lactate, I-FABP, endotoxin, and tight-junction proteins were investigated, and the fluorescein isothiocyanate-dextran (FD-4) test administered, to assess the degree of intestinal injury and integrity. Gut microbiota of rats in each group were analyzed by 16S rRNA sequencing. The results showed that pre-administration with BL significantly attenuated hyperthermia, reduced HS-induced death, alleviated multiple-organ injury, and decreased the levels of serum inflammatory cytokines. Furthermore, BL sustained the intestinal barrier integrity of HS rats by alleviating intestinal injury and improving tight junctions. We also found that BL significantly increased the ratios of two probiotic bacteria, Lactobacillus and Lactococcus. In addition, Romboutsia, a candidate biomarker for HS diagnosis, was unexpectedly detected. In summary, BL pre-administration for 7 days has preventative effects on HS that may be mediated by sustaining intestinal barrier function and modulating gut microbiota.

Probiotic Effects of Bacillus licheniformis DSM5749 on Growth Performance and Intestinal Microecological Balance of Laying Hens

“…Recent reports have demonstrated that B. licheniformis CGMCC 1.3448 enhances epithelial barrier integrity in laying hens ( 18 ) and B. licheniformis B26 in broiler chickens ( 52 ), characterized by the increased expression of ZO -1, Occludin and Claudin-1 at the mRNA level in the gut. A study suggested that B. licheniformis preadministration alleviated intestinal injury and improved gut barrier function during and after heat stroke (HS) onset ( 53 ). This research indicated that B. licheniformis maintained the mucosal barrier and intestinal health.…”

Overview of the Importance of Biotics in Gut Barrier Integrity

“…Moreover, the intestinal microbiota was rebalanced. Another study indicated the protective role of B. licheniformis CMCC 63516 on heat stroke in rats [ 59 ]. The B. licheniformis was introduced in quantity 10 8 CFU/mL twice daily for 7 days.…”

Potential Benefits of Probiotics and Prebiotics for Coronary Heart Disease and Stroke

“…bulgaricus) , and L. acidophilus improved ischemia via the mechanisms involved in anti-oxidation and anti-inflammation and ameliorated neurological deficits [ 75 , 76 ]. The intake of probiotic Bacillus licheniformis CMCC 63516 showed preventive effects on heat stroke in rats by sustaining intestinal barrier function, such as increasing tight junctions and decreasing intestinal injury and modulating gut microbiota, e.g., increasing the ratio of Lactobacillus and Lactococcus in the gut microbiota [ 77 ]. Moreover, the protective effect of Lactobacillus amylovorus DSM 16698T (ILA) on cerebral ischemia reperfusion injury in rats was observed through attenuating cerebral infarction volume and neural cell apoptosis, decreasing the levels of MDA and TLR-4, and increasing superoxide dismutase (SOD) activity [ 78 ].…”

“…The abovementioned research regarding the role of probiotics in CHD revealed that administration of pure probiotic strains or the co-supplementation of probiotics with other products attenuated levels of hs-CPR and other inflammatory factors [ 67 , 68 , 69 , 70 , 71 ]. In addition, the anti-inflammatory effects of probiotics on stroke by decreasing the expression of tight junction proteins and inflammatory cytokines such as TNF-α were observed [ 76 , 77 , 78 ]. Although these studies demonstrated that the introduction of probiotics is associated with anti-inflammatory effects on CHD and stroke, the mechanism of this action is yet to be investigated.…”

“…The intake of probiotic strains, such as L. plantarum 299v and L. rhamnosus GG, could improve CVD via alleviating inflammatory responses, which include decreased IL-8, IL-12, IL-1β, and TNF-α in patients [ 72 , 73 , 74 ]. In addition, it has been reported that the induction of probiotics C. butyricum , B. breve , L. casei , L. bulgaricus , L. acidophilus , and Bacillus licheniformis showed preventive effects on stoke along with reduced levels of inflammatory cytokines in both mice and rats [ 75 , 76 , 77 , 78 ]. In addition, probiotics could alter specific commensal bacteria of the gut microbiota, such as Prevotella and Oscillibacter , which have been shown to produce anti-inflammatory metabolites and thus decrease Th17 polarization and promote the differentiation of anti-inflammatory T reg /Type 1 regulatory T (Tr1) cells in the gut [ 111 ].…”