Lactobacillus reuteri in its biofilm state promotes neurodevelopment after experimental necrotizing enterocolitis in rats

Cell-Free Supernatant of Lactobacillus rhamnosus and Bifidobacterium breve Ameliorates Ischemic Stroke-Generated Neurological Deficits in Rats

The beneficial effects of probiotics, postbiotics, and paraprobiotics have already been registered in managing ischemic stroke-generated neuroinflammation and gut dysbiosis. Herein, we examined the impact of cell-free supernatant (CFS) obtained from probiotics (Lactobacillus rhamnosus UBLR-58 and Bifidobacterium breve UBBr-01) in a rat transient middle cerebral artery occlusion (MCAO) model of focal cerebral injury. Pre-MCAO supplementation of probiotics (2 × 109 CFU/mL) for 21 days or CFS (1 mL/rat) for 7 days protect the MCAO-induced somatosensory and motor impairments recorded at 24 h and 72 h after reperfusion in foot-fault, rotarod, adhesive removal, and vibrissae-evoked forelimb placing tests. We also noted the reduced infarct area and neuronal degradation in the right hemisphere of probiotics- and CFS-recipient MCAO-operated animals. Moreover, MCAO-induced altered concentrations of glial-fibrillary acidic protein, NeuN, zonula occludens-1 (ZO-1), TLR4, IL-1β, IL-6, and TNF-α, as well as matrix metalloproteinase-9 (MMP9) were reversed in the treatment groups. Probiotics and CFS treatment ameliorated the elevated levels of IL-6, IL-1β, and MMP9 in the blood plasma of rats. The disrupted microbial phyla, Firmicutes-to-Bacteroides ratio, villi/crypt ratio, and decreased mucin-producing goblet cells, ZO-1, and occludin in the colon of MCAO-operated rats were recovered following probiotics and CFS treatment. NMR characterization of CFS and rat blood plasma revealed the presence of several important bacterial metabolites. These findings suggest that the CFS obtained from Lactobacillus rhamnosus UBLR-58 and Bifidobacterium breve UBBr-01 has the propensity to improve MCAO-generated neurological dysfunctions in rats by dampening neuroinflammation and modulating the gut-brain axis modulators.

Effect of Oral Chondroitin Sulfate Supplementation on Acute Brain Injury in a Murine Necrotizing Enterocolitis Model

BACKGROUND

Necrotizing enterocolitis (NEC) is a devastating condition where inflammatory changes and necrosis in the gut results in activation of brain microglia and subsequent neurodevelopmental impairment. Chondroitin sulfate (CS) is a glycosaminoglycan in human breast milk that is absent in conventional formulas. We hypothesized that oral formula supplementation with CS during a murine model of experimental NEC would not only attenuate intestinal injury, but also brain injury.

STUDY DESIGN

NEC was induced in mouse pups on postnatal days (PNDs) 5 to 8. Three conditions were studied: (1) breastfed controls, (2) NEC, and (3) NEC+enteral CS (formula+200 mg/kg/d of CS). Pups were euthanized on PND 9 or reunited with dams by the evening of PND 8. Intestinal segments were H&E stained, and immunohistochemistry was performed on brain tissue for Iba-1 to assess for microglial morphology and cortical changes. Neurodevelopmental assays were performed on mice reunited with foster dams on PND 9. Single-cell RNA-sequencing analysis was performed on human intestinal epithelial cells exposed to (1) nothing, (2) hydrogen peroxide (H 2 O 2 ) alone, or (3) H 2 O 2 + CS to look at the differential gene expression between groups. Groups were compared with ANOVA or Kruskal-Wallis tests as appropriate with p < 0.05 considered significant.

RESULTS

Compared with NEC, mice treated with oral CS showed improved clinical outcomes, decreased intestinal injury, and attenuated microglial activation and deleterious cortical change. Mice with CS performed better on early neurodevelopmental assays when compared with NEC alone. Single-cell analysis of HIEC-6 cells demonstrated that CS treatment down regulated several inflammatory pathways including nuclear factor κB-suggesting an explanation for the improved Th17 intestinal cytokine profile.

CONCLUSIONS

Oral CS supplementation improved both physiological, clinical, and developmental outcomes. These data suggest that CS is a safe compound for formula supplementation for the prevention of NEC.

Superior performance of biofilm versus planktonic Limosilactobacillus reuteri in protection of the intestines and brain in a piglet model of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of gastrointestinal-related death in premature infants. Its etiology is multifactorial, with intestinal dysbiosis playing a major role. Probiotics are a logical preventative therapy for NEC, however their benefits have been inconsistent. We previously developed a novel probiotic delivery system in which planktonic (free-living) Limosilactobacillus reuteri (Lr) is incubated with biocompatible dextranomer microspheres (DM) loaded with maltose (Lr-DM-maltose) to induce biofilm formation. Here we have investigated the effects of Lr-DM-maltose in an enteral feed-only piglet model of NEC. We found a significant decrease in the incidence of Definitive NEC (D-NEC), death associated with D-NEC, and activated microglia in the brains of piglets treated with Lr-DM-maltose compared to non-treated piglets. Microbiome analyses using 16S rRNA sequencing of colonic contents revealed a significantly different microbial community composition between piglets treated with Lr-DM-maltose compared to non-treated piglets, with an increase in Lactobacillaceae and a decrease in Clostridiaceae in Lr-DM-maltose-treated piglets. Furthermore, there was a significant decrease in the incidence of D-NEC between piglets treated with Lr-DM-maltose compared to planktonic Lr. These findings validate our previous results in rodents, and support future clinical trials of Lr in its biofilm state for the prevention of NEC in premature neonates.

Brain effects of gestating germ-free persist in mouse neonates despite acquisition of a microbiota at birth

At birth, mammals experience a massive colonization by microorganisms. We previously reported that newborn mice gestated and born germ-free (GF) have increased microglial labeling and alterations in developmental neuronal cell death in the hippocampus and hypothalamus, as well as greater forebrain volume and body weight when compared to conventionally colonized (CC) mice. To test whether these effects are solely due to differences in postnatal microbial exposure, or instead may be programmed in utero, we cross-fostered GF newborns immediately after birth to CC dams (GF→CC) and compared them to offspring fostered within the same microbiota status (CC→CC, GF→GF). Because key developmental events (including microglial colonization and neuronal cell death) shape the brain during the first postnatal week, we collected brains on postnatal day (P) 7. To track gut bacterial colonization, colonic content was also collected and subjected to 16S rRNA qPCR and Illumina sequencing. In the brains of GF→GF mice, we replicated most of the effects seen previously in GF mice. Interestingly, the GF brain phenotype persisted in GF→CC offspring for almost all measures. In contrast, total bacterial load did not differ between the CC→CC and GF→CC groups on P7, and bacterial community composition was also very similar, with a few exceptions. Thus, GF→CC offspring had altered brain development during at least the first 7 days after birth despite a largely normal microbiota. This suggests that prenatal influences of gestating in an altered microbial environment programs neonatal brain development.

Gut-Brain cross talk: The pathogenesis of neurodevelopmental impairment in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating condition of multi-factorial origin that affects the intestine of premature infants and results in high morbidity and mortality. Infants that survive contend with several long-term sequelae including neurodevelopmental impairment (NDI)-which encompasses cognitive and psychosocial deficits as well as motor, vision, and hearing impairment. Alterations in the gut-brain axis (GBA) homeostasis have been implicated in the pathogenesis of NEC and the development of NDI. The crosstalk along the GBA suggests that microbial dysbiosis and subsequent bowel injury can initiate systemic inflammation which is followed by pathogenic signaling cascades with multiple pathways that ultimately lead to the brain. These signals reach the brain and activate an inflammatory cascade in the brain resulting in white matter injury, impaired myelination, delayed head growth, and eventual downstream NDI. The purpose of this review is to summarize the NDI seen in NEC, discuss what is known about the GBA, explore the relationship between the GBA and perinatal brain injury in the setting of NEC, and finally, highlight the existing research into possible therapies to help prevent these deleterious outcomes.

Biofilm-based delivery approaches and specific enrichment strategies of probiotics in the human gut

The use of probiotics has been one of the effective strategies to restructure perturbed human gut microbiota following a disease or metabolic disorder. One of the biggest challenges associated with the use of probiotic-based gut modulation strategies is to keep the probiotic cells viable and stable during the gastrointestinal transit. Biofilm-based probiotics delivery approaches have emerged as fascinating modes of probiotic delivery in which probiotics show significantly greater tolerance and biotherapeutic potential, and interestingly probiotic biofilms can be developed on food-grade surfaces too, which is ideal for the growth and proliferation of bacterial cells for incorporation into food matrices. In addition, biofilms can be further encapsulated with food-grade materials or with bacterial self-produced biofilms. This review presents a newly emerging and unprecedently discussed techniques for the safe delivery of probiotics based on biofilms and further discusses newly emerging prebiotic materials which target specific gut microbiota groups for growth and proliferation.

Next-Generation Probiotic Therapy to Protect the Intestines From Injury

Probiotics are live microorganisms that, when administered in adequate amounts, provide health benefits to the host. Some strains of the probiotic Lactobacillus reuteri (L. reuteri) have both antimicrobial and anti-inflammatory properties that may be exploited for the treatment and prevention of different gastrointestinal diseases, including necrotizing enterocolitis (NEC) and Clostridioides difficile (C. difficile) infection. Our laboratory has developed a new delivery system for L. reuteri in which the probiotic is incubated with biocompatible, semipermeable, porous dextranomer microspheres (DM) that can be loaded with beneficial and diffusible cargo. L. reuteri can be induced to form a biofilm by incubating the bacteria on the surface of these microspheres, which enhances the efficacy of the probiotic. Loading the DM with sucrose or maltose induces L. reuteri to produce more biofilm, further increasing the efficacy of the probiotic. Using a rat model of NEC, L. reuteri administered in its biofilm state significantly increases animal survival, reduces the incidence of NEC, preserves gut barrier function, and decreases intestinal inflammation. In a murine model of Clostridiodes difficile infection, L. reuteri administered in its biofilm state decreases colitis when administered either before or after C. difficile induction, demonstrating both prophylactic and therapeutic efficacy. There are currently no FDA-approved probiotic preparations for human use. An FDA-approved phase I clinical trial of L. reuteri in its biofilm state in healthy adults is currently underway. The results of this trial will be used to support a phase 1 clinical trial in neonates, with the goal of utilizing L. reuteri in its biofilm state to prevent NEC in premature neonates in the future.