Reproductive Senescence and Ischemic Stroke Remodel the Gut Microbiome and Modulate the Effects of Estrogen Treatment in Female Rats

Oral Microbiome Dysbiosis as a Risk Factor for Stroke: A Comprehensive Review

Stroke represents a significant global health burden, with a substantial impact on mortality, morbidity, and long-term disability. The examination of stroke biomarkers, particularly the oral microbiome, offers a promising avenue for advancing our understanding of the factors that contribute to stroke risk and for developing strategies to mitigate that risk. This review highlights the significant correlations between oral diseases, such as periodontitis and caries, and the onset of stroke. Periodontal pathogens within the oral microbiome have been identified as a contributing factor in the exacerbation of risk factors for stroke, including obesity, dyslipidemia, atherosclerosis, hypertension, and endothelial dysfunction. The alteration of the oral microbiome may contribute to these conditions, emphasizing the vital role of oral health in the prevention of cardiovascular disease. The integration of dental and medical health practices represents a promising avenue for enhancing stroke prevention efforts and improving patient outcomes.

Unveiling the potential of estrogen: Exploring its role in neuropsychiatric disorders and exercise intervention

Neuropsychiatric disorders shorten human life spans through multiple ways and become major threats to human health. Exercise can regulate the estrogen signaling, which may be involved in depression, Alzheimer's disease (AD) and Parkinson's disease (PD), and other neuropsychiatric disorders as well in their sex differences. In nervous system, estrogen is an important regulator of cell development, synaptic development, and brain connectivity. Therefore, this review aimed to investigate the potential of estrogen system in the exercise intervention of neuropsychiatric disorders to better understand the exercise in neuropsychiatric disorders and its sex specific. Exercise can exert a protective effect in neuropsychiatric disorders through regulating the expression of estrogen and estrogen receptors, which are involved in neuroprotection, neurodevelopment, and neuronal glucose homeostasis. These processes are mediated by the downstream factors of estrogen signaling, including N-myc downstream regulatory gene 2 (Ndrg2), serotonin (5-HT), delta like canonical Notch ligand 1 (DLL1), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), etc. In addition, exercise can act on the estrogen response element (ERE) fragment in the genes of estrogenic downstream factors like β-amyloid precursor protein cleavase 1 (BACE1). However, there are few studies on the relationship between exercise, the estrogen signaling pathway, and neuropsychiatric disorders. Hence, we review how the estrogen signaling mediates the mechanism of exercise intervention in neuropsychiatric disorders. We aim to provide a theoretical perspective for neuropsychiatric disorders affecting female health and provide theoretical support for the design of exercise prescriptions.

Impact of menopause-associated frailty on traumatic brain injury

Navigating menopause involves traversing a complex terrain of hormonal changes that extend far beyond reproductive consequences. Menopausal transition is characterized by a decrease in estradiol-17β (E2), and the impact of menopause resonates not only in the reproductive system but also through the central nervous system, musculoskeletal, and gastrointestinal domains. As women undergo menopausal transition, they become more susceptible to frailty, amplifying the risk and severity of injuries, including traumatic brain injury (TBI). Menopause triggers a cascade of changes leading to a decline in muscle mass, accompanied by diminished tone and excitability, thereby restricting the availability of irisin, a crucial hormone derived from muscles. Concurrently, bone mass undergoes reduction, culminating in the onset of osteoporosis and altering the dynamics of osteocalcin, a hormone originating from bones. The diminishing levels of E2 during menopause extend their influence on the gut microbiota, resulting in a reduction in the availability of tyrosine, tryptophan, and serotonin metabolites, affecting neurotransmitter synthesis and function. Understanding the interplay between menopause, frailty, E2 decline, and the intricate metabolisms of bone, gut, and muscle is imperative when unraveling the nuances of TBI after menopause. The current review underscores the significance of accounting for menopause-associated frailty in the incidence and consequences of TBI. The review also explores potential mechanisms to enhance gut, bone, and muscle health in menopausal women, aiming to mitigate frailty and improve TBI outcomes.

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.

Gut Microbiota in Ischemic Stroke: Role of Gut Bacteria-Derived Metabolites

Ischemic stroke (IS) remains a leading cause of death and long-term disability globally. Several mechanisms including glutamate excitotoxicity, calcium overload, neuroinflammation, oxidative stress, mitochondrial damage, and apoptosis are known to be involved in the pathogenesis of IS, but the underlying pathophysiology mechanisms of IS are not fully clarified. During the past decade, gut microbiota were recognized as a key regulator to affect the health of the host either directly or via their metabolites. Recent studies indicate that gut bacterial dysbiosis is closely related to hypertension, diabetes, obesity, dyslipidemia, and metabolic syndrome, which are the main risk factors for cardiovascular diseases. Increasing evidence indicates that IS can lead to perturbation in gut microbiota and increased permeability of the gut mucosa, known as "leaky gut," resulting in endotoxemia and bacterial translocation. In turn, gut dysbiosis and impaired intestinal permeability can alter gut bacterial metabolite signaling profile from the gut to the brain. Microbiota-derived products and metabolites, such as short-chain fatty acids (SCFAs), bile acids (BAs), trimethylamine N-oxide (TMAO), lipopolysaccharides (LPS), and phenylacetylglutamine (PAGln) can exert beneficial or detrimental effects on various extraintestinal organs, including the brain, liver, and heart. These metabolites have been increasingly acknowledged as biomarkers and mediators of IS. However, the specific role of the gut bacterial metabolites in the context of stroke remains incompletely understood. In-depth studies on these products and metabolites may provide new insight for the development of novel therapeutics for IS.

Estradiol mediates colonic epithelial protection in aged mice after stroke and is associated with shifts in the gut microbiome

The gut is a major source of bacteria and antigens that contribute to neuroinflammation after brain injury. Colonic epithelial cells (ECs) are responsible for secreting major cellular components of the innate defense system, including antimicrobial proteins (AMP) and mucins. These cells serve as a critical regulator of gut barrier function and maintain host-microbe homeostasis. In this study, we determined post-stroke host defense responses at the colonic epithelial surface in mice. We then tested if the enhancement of these epithelial protective mechanisms is beneficial in young and aged mice after stroke. AMPs were significantly increased in the colonic ECs of young males, but not in young females after experimental stroke. In contrast, mucin-related genes were enhanced in young females and contributed to mucus formation that maintains the distance between the host and gut bacteria. Bacterial community profiling was done using universal amplification of 16S rRNA gene sequences. The sex-specific colonic epithelial defense responses after stroke in young females were reversed with ovariectomy and led to a shift from a predominately mucin response to the enhanced AMP expression seen in males after stroke. Estradiol (E2) replacement prior to stroke in aged females increased mucin gene expression in the colonic ECs. Interestingly, we found that E2 treatment reduced stroke-associated neuronal hyperactivity in the insular cortex, a brain region that interacts with visceral organs such as the gut, in parallel to an increase in the composition of Lactobacillus and Bifidobacterium in the gut microbiota. This is the first study demonstrating sex differences in host defense mechanisms in the gut after brain injury.

Association analysis of the gut microbiota in predicting outcomes for patients with acute ischemic stroke and H-type hypertension

Introduction

H-type hypertension (HHTN) is a subtype of hypertension that tends to worsen the prognosis of acute ischemic stroke (AIS). Recent studies have highlighted the vital role of gut microbiota in both hypertension and AIS, but there is little available data on the relationship between gut microbiota and the progression of AIS patients with HHTN. In this study, we investigated the microbial signature of AIS patients with HHTN and identified characteristic bacteria as biomarkers for predicting prognosis.

Methods

AIS patients with HHTN (n = 150) and without HHTN (n = 50) were enrolled. All patients received a modified Rankin Scale (mRS) assessment at 3 months after discharge. Fecal samples were collected from the participants upon admission, including 150 AIS patients with HHTN, 50 AIS patients with non-HHTN, and 90 healthy subjects with HHTN. These samples were analyzed using 16S rRNA sequencing to characterize the bacterial taxa, predict functions, and conduct correlation analysis between specific taxa and clinical features.

Results

Our results showed that the composition of the gut microbiota in HHTN patients differed significantly from that in non-HHTN patients. The abundance of the genera Bacteroides, Escherichia-Shigella, Lactobacillus, Bifidobacterium, and Prevotella in AIS patients with HHTN was significantly increased compared to AIS patients without HHTN, while the genus Streptococcus, Faecalibacterium, and Klebsiella were significantly decreased. Moreover, Bacteroides, Lactobacillus, Bifidobacterium, and Klebsiella in AIS patients with HHTN were more abundant than healthy subjects with HHTN, while Escherichia-Shigella, Blautia, and Faecalibacterium were less abundant. Moreover, the genera Butyricicoccus, Rothia, and Family_XIII_UCG-001 were negatively connected with the NIHSS score, and the genera Butyricicoccus and Rothia were observed to be negatively associated with the mRS score. The genera Butyricicoccus, Romboutsia, and Terrisporobacter were associated with a poor prognosis, whereas the increase in Butyricimonas and Odoribacter was correlated with good outcomes. Generated by eight genera and clinical indexes, the area under the curve (AUC) value of the receiver operating characteristic (ROC) curve achieved 0.739 to effectively predict the prognosis of AIS patients with HHTN.

Conclusion

These findings revealed the microbial signature of AIS patients with HHTN and further provided potential microbial biomarkers for the clinical diagnosis of AIS patients with HHTN.

Application of omics technology to investigate the mechanism underlying the role of San Hua Tang in regulating microglia polarization and blood-brain barrier protection following ischemic stroke

ETHNOPHARMACOLOGY RELEVANCE

San Hua Tang (SHT) was first mentioned in the book "The Collection of Plain Questions about Pathogenesis, Qi, and Life." SHT has the effect of dispelling wind and dredging collaterals, dredging viscera, and guiding stagnation, and is used in the treatment of ischemic stroke (IS). SHT is composed of Rheum palmatum L., Magnolia officinalis Rehder & E.H.Wilson, Citrus assamensis S.Dutta & S.C.Bhattacharya, and Notopterygium tenuifolium M.L.Sheh & F.T.Pu, which is the traditional prescription of the Tongxia method for the treatment of stroke. Tongxia is one of the "eight methods" used in traditional Chinese medicine, which plays a role in treating diseases by promoting gastrointestinal peristalsis and defecation. Studies have demonstrated a close relationship between gut microbiota metabolism and cerebral stroke; however, the role of SHT in IS treatment through gut microbiota or intestinal metabolites is unclear.

AIM OF THE STUDY

To explore the connotation of the Xuanfu theory and clarify the mechanism underlying SHT-mediated opening Xuanfu methods. Through metabolomics, 16S rRNA gene sequencing, and molecular biology techniques, research on the changes in the gut microbiota and blood-brain barrier (BBB) will highlight greater strategies for the treatment of stroke.

MATERIALS AND METHODS

We used pseudo-germ-free (PGF) rats combined with an ischemia/reperfusion (I/R) rat model for the follow-up experimental research. PGF rats were prepared by the intragastric administration of an antibiotic cocktail for 6 days, following which SHT was administered for 5 consecutive days. The I/R model was performed 1 day following the concluding administration of SHT. We detected the neurological deficit score, cerebral infarct volume, serum inflammatory factor levels (interleukin IL-6, IL-10, IL-17, and tumor necrosis factor alpha), tight junction-related proteins (Zonula occludens-1, Occludin, and Claudin-5), and small glue plasma cell-associated proteins (Cluster of Differentiation 16/Cluster of Differentiation 206, Matrix metalloproteinase, ionized calcium-binding adapter molecule 1, and C-X3-C Motif Chemokine Ligand 1) 24 h following I/R. Using 16S rRNA gene sequencing and non-targeted metabolomics analysis, we explored the relationship between fecal microecology and serum metabolites. Eventually, we analyzed the correlation between the gut microbiota and plasma metabolic profile as well as the mechanism underlying the SHT-mediated regulation of gut microbiota to protect the BBB following stroke.

RESULTS

In IS treatment, SHT is principally involved in reducing neurological injury and the volume of cerebral infarction; protecting the intestinal mucosal barrier; increasing the levels of acetic acid, butyric acid, and propionic acid; promoting the transformation of microglia to the M2 state; reducing inflammatory reactions; and enhancing tight junctions. These therapeutic effects were not observed in the group treated with antibiotics alone or that treated with SHT in combination with antibiotics, thereby indicating SHT plays a therapeutic role through the gut microbiota.

CONCLUSION

SHT regulates the gut microbiota, inhibits pro-inflammatory factors in rats with IS, alleviates an inflammatory injury of the BBB, and plays a protective role in the brain.

The Diagnostic Value of Gut Microbiota Analysis for Post-Stroke Sleep Disorders

BACKGROUND

Gut microbiota have been associated with many psychiatric disorders. However, the changes in the composition of gut microbiota in patients with post-stroke sleep disorders (PSSDs) remain unclear. Here, we determined the gut microbial signature of PSSD patients.

METHODS

Fecal samples of 205 patients with ischemic stroke were collected within 24 h of admission and were further analyzed using 16 s RNA gene sequencing followed by bioinformatic analysis. The diversity, community composition, and differential microbes of gut microbiota were assessed. The outcome of sleep disorders was determined by the Pittsburgh Sleep Quality Index (PSQI) at 3 months after admission. The diagnostic performance of microbial characteristics in predicting PSSDs was assessed by receiver operating characteristic (ROC) curves.

RESULTS

Our results showed that the composition and structure of microbiota in patients with PSSDs were different from those without sleep disorders (PSNSDs). Moreover, the linear discriminant analysis effect size (LEfSe) showed significant differences in gut-associated bacteria, such as species of Streptococcus, Granulicatella, Dielma, Blautia, Paeniclostridium, and Sutterella. We further managed to identify the optimal microbiota signature and revealed that the predictive model with eight operational-taxonomic-unit-based biomarkers achieved a high accuracy in PSSD prediction (AUC = 0.768). Blautia and Streptococcus were considered to be the key microbiome signatures for patients with PSSD.

CONCLUSIONS

These findings indicated that a specific gut microbial signature was an important predictor of PSSDs, which highlighted the potential of microbiota as a promising biomarker for detecting PSSD patients.

The Intestinal Microbiome in Dogs with Chronic Enteropathies and Cobalamin Deficiency or Normocobalaminemia-A Comparative Study

Cobalamin deficiency is a common sequela of chronic enteropathies (CE) in dogs. Studies comparing the intestinal microbiome of CE dogs with cobalamin deficiency to those that are normocobalaminemic are lacking. Therefore, our aim was to describe the fecal microbiome in a prospective, comparative study evaluating 29 dogs with CE and cobalamin deficiency, 18 dogs with CE and normocobalaminemia, and 10 healthy control dogs. Dogs with cobalamin deficiency were also analyzed after oral or parenteral cobalamin supplementation. Overall microbiome composition (beta diversity) at baseline was significantly different in CE dogs with cobalamin deficiency when compared to those with normocobalaminemia (p = 0.001, R = 0.257) and to healthy controls (p = 0.001, R = 0.363). Abundances of Firmicutes and Actinobacteria were significantly increased (q = 0.010 and 0.049), while those of Bacteroidetes and Fusobacteria were significantly decreased (q = 0.002 and 0.014) in CE dogs with cobalamin deficiency when compared to healthy controls. Overall microbiome composition in follow-up samples remained significantly different after 3 months in both dogs receiving parenteral (R = 0.420, p = 0.013) or oral cobalamin supplementation (R = 0.251, p = 0.007). Because cobalamin supplementation, in combination with appropriate therapy, failed to restore the microbiome composition in the dogs in our study, cobalamin is unlikely to be the cause of those microbiome changes but rather an indicator of differences in underlying pathophysiology that do not influence clinical severity but result in a significant aggravation of dysbiosis.

Secukinumab attenuates neuroinflammation and neurobehavior defect via PKCβ/ERK/NF-κB pathway in a rat model of GMH

AIMS

Germinal matrix hemorrhage (GMH) is a disastrous clinical event for newborns. Neuroinflammation plays an important role in the development of neurological deficits after GMH. The purpose of this study is to investigate the anti-inflammatory role of secukinumab after GMH and its underlying mechanisms involving PKCβ/ERK/NF-κB signaling pathway.

METHODS

A total of 154 Sprague-Dawley P7 rat pups were used. GMH was induced by intraparenchymal injection of bacterial collagenase. Secukinumab was administered intranasally post-GMH. PKCβ activator PMA and p-ERK activator Ceramide C6 were administered intracerebroventricularly at 24 h prior to GMH induction, respectively. Neurobehavioral tests, western blot and immunohistochemistry were used to evaluate the efficacy of Secukinumab in both short-term and long-term studies.

RESULTS

Endogenous IL-17A, IL-17RA, PKCβ and p-ERK were increased after GMH. Secukinumab treatment improved short- and long-term neurological outcomes, reduced the synthesis of MPO and Iba-1 in the perihematoma area, and inhibited the synthesis of proinflammatory factors, such as NF-κB, IL-1β, TNF-α and IL-6. Additionally, PMA and ceramide C6 abolished the beneficial effects of Secukinumab.

CONCLUSION

Secukinumab treatment suppressed neuroinflammation and attenuated neurological deficits after GMH, which was mediated through the downregulation of the PKCβ/ERK/NF-κB pathway. Secukinumab treatment may provide a promising therapeutic strategy for GMH patients.

Involvement of baroreflex deficiency in the age-related loss of estrogen efficacy against cerebral ischemia

For post-menopausal women, stroke is complicated by the variable effects of estrogen therapy and the age-related therapeutic consequences involved. Estrogen therapy has been shown to have an age-dimorphic effect, which is neuroprotective in young females, but non-neuroprotective, even neurotoxic in acyclic females. We hypothesized that arterial baroreflex (ABR) and its downstream acetylcholine-α7 nicotinic acetylcholine receptor (α7nAChR) anti-inflammatory pathways are involved in estrogen efficacy toward cerebral ischemic damage. Our data showed that estrogen supplements contributed to ABR improvement and neuroprotection in adult, not aged, ovariectomized (OVX) rats. In adult rats, OVX-induced estrogen deficiency aggravated middle cerebral artery occlusion (MCAO), which induced brain infarction and reduced ABR function, with decreased α7nAChR expression of the brain and exaggerated inflammation following MCAO; these effects were significantly prevented by supplementation with estrogen. ABR impairment by sinoaortic denervation partly attenuated the estrogen effect on baroreflex sensitivity (BRS) and ischemic damage in adult rats, as well as α7nAChR expression and inflammatory response. These data suggested that ABR and acetylcholine-α7nAChR anti-inflammatory pathways are involved in the neuroprotection of estrogen in adult OVX rats. In contrast, aged rats exhibited more severe ischemic damage and inflammatory response than adult rats, as well as poorer baroreflex function and lower α7nAChR expression. Estrogen supplements did not improve BRS or confer neuroprotection in aged rats without affecting brain α7nAChR and post-ischemic inflammation. Most importantly, ketanserin restored ABR function and significantly postponed the onset of stroke in aged female strokeprone spontaneously hypertensive rats, whereas estrogen treatment failed to delay the development of stroke. Our findings reveal that estrogen is protective against ischemic stroke (IS) in adult female rats and that ABR played a role in this beneficial action. Dysfunction of ABR and unresponsiveness to estrogen in aged female rats may contribute to a reduced estrogen efficacy against cerebral ischemia.

Human Cord Blood-Endothelial Progenitor Cells Alleviate Intimal Hyperplasia of Arterial Damage in a Rat Stroke Model

Human cord blood-endothelial progenitor cells (hCB-EPCs) isolated from the human umbilical cord can be used to repair damaged arteries. In this study, we used an animal model with pathological changes that mimics artery wall damage caused by stent retrievers in humans. We injected hCB-EPCs to investigate their effect on endothelial hyperplasia and dysfunction during intimal repair. Four groups were established based on the length of reperfusion (3 and 28 days), as well as the presence or absence of hCB-EPC therapy. Damage to the internal carotid artery was evaluated by hematoxylin-eosin and immunohistochemical staining. Stroke volume was not significantly different between non-EPC and EPC groups although EPC treatment alleviated intimal hyperplasia 28 days after intimal damage. Vascular endothelial growth factor (VEGF) and eNOS expression were significantly higher in the EPC-treated group than in the non-EPC group 3 days after intimal damage. In addition, MMP9 and 4HNE expression in the EPC-treated group was significantly lower than in the non-EPC group. Ultimately, this study found that venous transplantation of hCB-EPCs could inhibit neointimal hyperplasia, alleviate endothelial dysfunction, suppress intimal inflammation, and reduce oxidative stress during healing of intimal damage.

Gut microbial dysbiosis correlates with stroke severity markers in aged rats

Background

An imbalanced gut microbial community, or dysbiosis, has been shown to occur following stroke. It is possible that this dysbiosis negatively impacts stroke recovery and rehabilitation. Species level resolution measurements of the gut microbiome following stroke are needed to develop and test precision interventions such as probiotic or fecal microbiota transplant therapies that target the gut microbiome. Previous studies have used 16S rRNA amplicon sequencing in young male mice to obtain broad profiling of the gut microbiome at the genus level following stroke, but further investigations will be needed with whole genome shotgun sequencing in aged rats of both sexes to obtain species level resolution in a model which will better translate to the demographics of human stroke patients.

Methods

Thirty-nine aged male and female rats underwent middle cerebral artery occlusion. Fecal samples were collected before stroke and 3 days post stroke to measure gut microbiome. Machine learning was used to identify the top ranked bacteria which were changed following stroke. MRI imaging was used to obtain infarct and edema size and cerebral blood flow (CBF). ELISA was used to obtain inflammatory markers.

Results

Dysbiosis was demonstrated by an increase in pathogenic bacteria such as Butyricimonas virosa (15.52 fold change, p < 0.0001), Bacteroides vulgatus (7.36 fold change, p < 0.0001), and Escherichia coli (47.67 fold change, p < 0.0001). These bacteria were positively associated with infarct and edema size and with the inflammatory markers Ccl19, Ccl24, IL17a, IL3, and complement C5; they were negatively correlated with CBF. Conversely, beneficial bacteria such as Ruminococcus flavefaciens (0.14 fold change, p < 0.0001), Akkermansia muciniphila (0.78 fold change, p < 0.0001), and Lactobacillus murinus (0.40 fold change, p < 0.0001) were decreased following stroke and associated with all the previous parameters in the opposite direction of the pathogenic species. There were not significant microbiome differences between the sexes.

Conclusion

The species level resolution measurements found here can be used as a foundation to develop and test precision interventions targeting the gut microbiome following stroke. Probiotics that include Ruminococcus flavefaciens, Akkermansia muciniphila, and Lactobacillus murinus should be developed to target the deficit following stroke to measure the impact on stroke severity.

Sex differences in the diathetic effects of shift work schedules on circulating cytokine levels and pathological outcomes of ischemic stroke during middle age

Shift work is associated with increased risk for vascular disease, including stroke- and cardiovascular-related mortality. However, evidence from these studies is inadequate to distinguish the effect of altered circadian rhythms in isolation from other risk factors for stroke associated with shift work (e.g., smoking, poor diet, lower socioeconomic status). Thus, the present study examined the diathetic effects of exposure to shifted LD cycles during early adulthood on circadian rhythmicity, inflammatory signaling and ischemic stroke pathology during middle age, when stroke risk is high and outcomes are more severe. Entrainment of circadian activity was stable in all animals maintained on a fixed light:dark 12:12 cycle but was severely disrupted during exposure to shifted LD cycles (12hr advance/5d). Following treatment, circadian entrainment in the shifted LD group was distinguished by increased daytime activity and decreased rhythm amplitude that persisted into middle-age. Circadian rhythm desynchronization in shifted LD males and females was accompanied by significant elevations in circulating levels of the inflammatory cytokine IL-17A and gut-derived inflammatory mediator lipopolysaccharide (LPS) during the post-treatment period. Middle-cerebral artery occlusion, 3 months after exposure to shifted LD cycles, resulted in greater post-stroke mortality in shifted LD females. In surviving subjects, sensorimotor performance, assessed 2- and 5-days post-stroke, was impaired in males of both treatment groups, whereas in females, recovery of function was observed in fixed but not shifted LD rats. Overall, these results indicate that early exposure to shifted LD cycles promotes an inflammatory phenotype that amplifies stroke impairments, specifically in females, later in life.

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Early exposure to shifted LD cycles alters circadian entrainment of the activity rhythm that persists into middle age.

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In conjunction with circadian dysregulation, shift work-like schedules promote the induction of key inflammatory mediators.

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In females, exposure to shift work-like schedules amplifies functional impairments caused by strokes arising later in life.

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Circadian dysregulation during shift work is a hysteretic risk factor in the overall severity of ischemic strokes.

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Shift work-related circadian dysregulation affects stroke outcomes independent of lifestyle vascular disease risk factors.

Gut microbes in cerebrovascular diseases: Gut flora imbalance, potential impact mechanisms and promising treatment strategies

The high morbidity, mortality, and disability rates associated with cerebrovascular disease (CeVD) pose a severe danger to human health. Gut bacteria significantly affect the onset, progression, and prognosis of CeVD. Gut microbes play a critical role in gut-brain interactions, and the gut-brain axis is essential for communication in CeVD. The reflection of changes in the gut and brain caused by gut bacteria makes it possible to investigate early warning biomarkers and potential treatment targets. We primarily discussed the following three levels of brain-gut interactions in a systematic review of the connections between gut microbiota and several cerebrovascular conditions, including ischemic stroke, intracerebral hemorrhage, intracranial aneurysm, cerebral small vessel disease, and cerebral cavernous hemangioma. First, we studied the gut microbes in conjunction with CeVD and examined alterations in the core microbiota. This enabled us to identify the focus of gut microbes and determine the focus for CeVD prevention and treatment. Second, we discussed the pathological mechanisms underlying the involvement of gut microbes in CeVD occurrence and development, including immune-mediated inflammatory responses, variations in intestinal barrier function, and reciprocal effects of microbial metabolites. Finally, based on the aforementioned proven mechanisms, we assessed the effectiveness and potential applications of the current therapies, such as dietary intervention, fecal bacterial transplantation, traditional Chinese medicine, and antibiotic therapy.

Alterations in gut microbiota are related to metabolite profiles in spinal cord injury

Studies have shown that gut microbiota metabolites can enter the central nervous system via the blood-spinal cord barrier and cause neuroinflammation, thus constituting secondary injury after spinal cord injury. To investigate the correlation between gut microbiota and metabolites and the possible mechanism underlying the effects of gut microbiota on secondary injury after spinal cord injury, in this study, we established mouse models of T8-T10 traumatic spinal cord injury. We used 16S rRNA gene amplicon sequencing and metabolomics to reveal the changes in gut microbiota and metabolites in fecal samples from the mouse model. Results showed a severe gut microbiota disturbance after spinal cord injury, which included marked increases in pro-inflammatory bacteria, such as Shigella, Bacteroides, Rikenella, Staphylococcus, and Mucispirillum and decreases in anti-inflammatory bacteria, such as Lactobacillus, Allobaculum, and Sutterella. Meanwhile, we identified 27 metabolites that decreased and 320 metabolites that increased in the injured spinal cord. Combined with pathway enrichment analysis, five markedly differential amino acids (L-leucine, L-methionine, L-phenylalanine, L-isoleucine and L-valine) were screened out, which play a pivotal role in activating oxidative stress and inflammatory responses following spinal cord injury. Integrated correlation analysis indicated that the alteration of gut microbiota was related to the differences in amino acids, which suggests that disturbances in gut microbiota might participate in the secondary injury through the accumulation of partial metabolites that activate oxidative stress and inflammatory responses. Findings from this study provide a new theoretical basis for improving the secondary injury after spinal cord injury through fecal microbial transplantation.

The effect of fecal microbiota transplantation on stroke outcomes: A systematic review

BACKGROUND AND PURPOSE

Fecal microbiota transplantation (FMT) is a novel microbiota-based therapeutic method that transfers stool from donor into a recipient and its application is under investigating for neurological disorders such as stroke. In this systematic review, we assessed the effect of FMT in progression and treatment of stroke and recovery of post-stroke complications.

METHODS

Preliminary studies were searched in MEDLINE via PubMed, Scopus, COCHRANE library and Google Scholar, databases up to February 2022. The search strategy was restricted to articles about FMT in stroke. The initial search yielded 4570 articles, of which 19 publications were included in our systematic review.

RESULTS

Based on outcomes transferring microbiome from healthy or ischemic donor to other ischemic recipient can affect brain infarct volume and survival rate, neurological and behavioral outcomes, and inflammatory pathways.

CONCLUSIONS

Our systematic review on preclinical studies showed that manipulating gut microbiota via FMT can be a possible therapeutic approach for treatment of stroke and recovery of post-stroke complications.

Novel Mechanisms and Therapeutic Targets for Ischemic Stroke: A Focus on Gut Microbiota

Ischemic stroke is the most common type of stroke with limited treatment options. Although the pathological mechanisms and potential therapeutic targets of ischemic stroke have been comprehensively studied, no effective therapies were translated into clinical practice. Gut microbiota is a complex and diverse dynamic metabolic ecological balance network in the body, including a large number of bacteria, archaea, and eukaryotes. The composition, quantity and distribution in gut microbiota are found to be associated with the pathogenesis of many diseases, such as individual immune abnormalities, metabolic disorders, and neurodegeneration. New insight suggests that ischemic stroke may lead to changes in the gut microbiota and the alterations of gut microbiota may determine stroke outcomes in turn. The link between gut microbiota and stroke is expected to provide new perspectives for ischemic stroke treatment. In this review, we discuss the gut microbiota alterations during ischemic stroke and gut microbiota-related stroke pathophysiology and complications. Finally, we highlight the role of the gut microbiota as a potential therapeutic target for ischemic stroke and summarize the microbiome-based treatment options that can improve the recovery of stroke patients.

Gut dysbiosis and age-related neurological diseases in females

Historically, females have been underrepresented in biological research. With increased interest in the gut microbiome and the gut-brain axis, it is important for researchers to pursue studies that consider sex as a biological variable. The composition of the gut microbiome is influenced by environmental factors, disease, diet, and varies with age and by sex. Detrimental changes in the gut microbiome, referred to as dysbiosis, is believed to influence the development and progression of age-related neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and stroke. Many are investigating the changes in microbial populations in order or to better understand the role of the gut immunity and the microbiome in neurodegenerative diseases, many of which the exact etiology remains elusive, and no cures exist. Others are working to find diagnostic markers for earlier detection, or to therapeutically modulate microbial populations using probiotics. However, while all these diseases present in reproductively senescent females, most studies only use male animals for their experimental design. Reproductively senescent females have been shown to have differences in disease progression, inflammatory responses, and microbiota composition, therefore, for research to be translational to affected populations it is necessary for appropriate models to be used. This review discusses factors that influence the gut microbiome and the gut brain axis in females, and highlights studies that have investigated the role of dysbiosis in age-related neurodegenerative disorders that have included females in their study design.

Dynamic Alteration of the Gut Microbiota Associated with Obesity and Intestinal Inflammation in Ovariectomy C57BL/6 Mice

OBJECTIVE

Estrogen is a critical hormone that is mainly produced by the ovary in females. Estrogen deficiency leads to various syndromes and diseases, partly due to gut microbiota alterations. Previous studies have shown that estrogen deficiency affects the gut microbiota at 6-8 weeks after ovariectomy, but the immediate effect of estrogen deficiency on the gut microbiota remains poorly understood.

METHODS

To investigate the short time and dynamic effects of decreased estrogen levels on the gut microbiota and their potential impact on estrogen deficiency-related diseases, we performed metagenomic sequencing of 260 fecal samples from 50 ovariectomy (OVX) and 15 control C57BL/6 female mice at four time points after surgery.

RESULTS

We found that seven gut microbiota species, including E. coli, Parabacteroides unclassified, Lachnospiraceae bacterium 8_1_57FAA, Bacteroides uniformis, Veillonella unclassified, Bacteroides xylanisolvens, and Firmicutes bacterium M10_2, were abundant in OVX mice. The abundance of these species increased with time after OVX surgery. The relative abundance of the opportunistic pathogen E. coli and the Crohn's disease-related Veillonella spp. was significantly correlated with mouse weight gain in the OVX group. Butyrate production and the Entner-Doudoroff pathway were significantly enriched in the control mouse group, while the degradation of glutamic acid and aspartic acid was enriched in the OVX mouse group. As the time after OVX surgery increased, the bacterial species and metabolic pathways significantly changed and tended to suggest an inflammatory environment, indicating a subhealthy state of the gut microbiota in the OVX mouse group.

CONCLUSIONS

Taken together, our results show that the dynamic gut microbiota profile alteration caused by estrogen deficiency is related to obesity and inflammation, which may lead to immune and metabolic disorders. This study provides new clues for the treatment of estrogen deficiency-related diseases.

Impact of intestinal disorders on central and peripheral nervous system diseases

Brain injuries and neurological diseases have a significant impact on the gut microbiome and the gut barrier. Reciprocally, gut disorders, such as Inflammatory Bowel Syndromes (IBS), can affect the development and pathology of neurodegenerative and neuropsychiatric diseases, although this aspect is less well studied and is the focus of this review. Inflammatory Bowel Syndrome (IBS) is a chronic and debilitating functional gastrointestinal disorder afflicting an estimated 9-23% of the world's population. A hallmark of this disease is leaky gut, a pathology in which the integrity of the gut blood barrier is compromised, causing gut contents such as immune cells and microbiota to enter the bloodstream leading to low-grade systemic inflammation. The increased levels of inflammation associated cytokines in circulation has the potential to affect all organs, including the brain. Although the brain is protected by the blood brain barrier, inflammation associated cytokines can damage the junctions in this barrier and allow brain infiltration of peripheral immune cells. Central inflammation in the brain is associated with various neurodegenerative disease such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, and neuropsychiatric disorders, namely, depression, and anxiety. Neurodegenerative diseases are of particular concern due to the anticipated rise in the population of the elderly and consequently, the prevalence of these diseases. Additionally, depression and anxiety are the most common mental illnesses affecting roughly 18% of the American population. In this review, we will explore the mechanisms by which IBS can influence the risk and severity of neurological disease.

Distinct gut microbiomes in two polar bear subpopulations inhabiting different sea ice ecoregions

Gut microbiomes were analyzed by 16S rRNA gene metabarcoding for polar bears (Ursus maritimus) from the southern Beaufort Sea (SB), where sea ice loss has led to increased use of land-based food resources by bears, and from East Greenland (EG), where persistent sea ice has allowed hunting of ice-associated prey nearly year-round. SB polar bears showed a higher number of total (940 vs. 742) and unique (387 vs. 189) amplicon sequence variants and higher inter-individual variation compared to EG polar bears. Gut microbiome composition differed significantly between the two subpopulations and among sex/age classes, likely driven by diet variation and ontogenetic shifts in the gut microbiome. Dietary tracer analysis using fatty acid signatures for SB polar bears showed that diet explained more intrapopulation variation in gut microbiome composition and diversity than other tested variables, i.e., sex/age class, body condition, and capture year. Substantial differences in the SB gut microbiome relative to EG polar bears, and associations between SB gut microbiome and diet, suggest that the shifting foraging habits of SB polar bears tied to sea ice loss may be altering their gut microbiome, with potential consequences for nutrition and physiology.

Altered fecal microbiota, IgA, and fermentative end-products in adult dogs fed prebiotics and a nonviable Lactobacillus acidophilus

A study investigating the use of a nonviable Lactobacillus acidophilus (NVL: Culbac; TransAgra, Storm Lake, IA) and a mixed prebiotic (MP) blend (beet pulp, fructooligosaccharide (FOS), mannanoligosaccharide (MOS), inulin, and kelp) was done to evaluate changes in fecal microbiota, fermentative end products, and gut immune health in healthy female and male adult Beagle dogs (n = 24; 5.74 ± 2.18 yr; 9.30 ± 1.32 kg). The study protocol was first approved by the facility's Institutional Animal Care and Use Committee (Summit Ridge Farms; Susquehanna, PA) and followed throughout. Each of four test diets (control, NVL, MP, and MP + NVL [formulated to crude protein 25%, crude fat 14%, crude fiber 10% as-fed]) was fed once daily to maintain body weight for 21 d in a randomized-crossover design (four treatment periods and four washout periods). Fecal samples were collected on days 0 and 21 only for immunoglobulin A (IgA) and microbiota evaluation (16S rRNA V4 region and qPCR for Escherichia coli and Bifidobacterium), and fecal fermentative end-products and fecal pH were assessed only on day 21. Over the test periods, apparent total tract nutrient digestibility and stool quality were assessed. Data were analyzed by ANOVA (SAS v9.4, Cary, NC) or Kruskal-Wallis for between-diet effects, and paired t-test or Wilcoxon for time effects. Statistical significance was set at P ≤ 0.05. Apparent total tract nutrient digestibility revealed feeding MP-containing diets resulted in lower (P < 0.05) crude protein and fat digestibility vs. control and NVL diets. When dogs were fed MP, they had lower (P < 0.05) fecal pH compared with control and NVL diets, whereas fecal pH was lower in (P < 0.05) MP + NVL- vs. NVL-fed dogs. Fecal E. coli was (P < 0.05) lower at day 21 vs. day 0 when dogs were fed MP. Fecal Fusobacterium spp. was lower (P < 0.05) in both MP diets vs. control. Fecal Lactobacillus spp. increased (P < 0.05) from baseline with MP. Both diets with MP elicited greater (P < 0.05) fecal acetate and propionate concentration vs. control diet. At day 21, fecal IgA was greater (P < 0.05) in MP and MP + NVL compared with NVL diet. Only when dogs were fed MP did they have increased (P < 0.05) fecal IgA from day 21 vs. day 0. The MP + NVL diet decreased (P < 0.05) fecal isovalerate, isobutyrate, phenol, and indole vs. control. Overall, the MP elicited the most changes on microbiota, fermentative end-products, and IgA. Further investigation into NVL's gut health benefits is warranted.

Surgical Menopause and Estrogen Therapy Modulate the Gut Microbiota, Obesity Markers, and Spatial Memory in Rats

Menopause in human females and subsequent ovarian hormone deficiency, particularly concerning 17β-estradiol (E2), increase the risk for metabolic dysfunctions associated with obesity, diabetes type 2, cardiovascular diseases, and dementia. Several studies indicate that these disorders are also strongly associated with compositional changes in the intestinal microbiota; however, how E2 deficiency and hormone therapy affect the gut microbial community is not well understood. Using a rat model, we aimed to evaluate how ovariectomy (OVX) and subsequent E2 administration drive changes in metabolic health and the gut microbial community, as well as potential associations with learning and memory. Findings indicated that OVX-induced ovarian hormone deficiency and E2 treatment had significant impacts on several health-affecting parameters, including (a) the abundance of some intestinal bacterial taxa (e.g., Bifidobacteriaceae and Porphyromonadaceae), (b) the abundance of microbial short-chain fatty acids (SCFAs) (e.g., isobutyrate), (c) weight/BMI, and (d) high-demand spatial working memory following surgical menopause. Furthermore, exploratory correlations among intestinal bacteria abundance, cognition, and BMI underscored the putative influence of surgical menopause and E2 administration on gut-brain interactions. Collectively, this study showed that surgical menopause is associated with physiological and behavioral changes, and that E2-linked compositional changes in the intestinal microbiota might contribute to some of its related negative health consequences. Overall, this study provides novel insights into interactions among endocrine and gastrointestinal systems in the post-menopausal life stage that collectively alter the risk for the development and progression of cardiovascular, metabolic, and dementia-related diseases.

Influence of the gut microbiome on inflammatory and immune response after stroke

Researches on the bidirectional communications between the gut microbiota and brain, termed the gut-brain axis, often bring about discoveries and drive the development of medicine and biology for stroke. Following stroke, the gut-brain axis is perturbed significantly on dysbiotic gut microbiome, intestinal dysfunction, enteric nervous system, increased gut permeability, and activated immune cells in the gut, which in turn results in infiltration of pro-inflammatory cells or bacterial toxins into brain tissue through impaired blood-brain barrier (BBB), finally exacerbated brain infarction. Herein, we illuminate the changes in the immune system and highlight the possible mechanisms of the gut microbiota to regulate inflammatory and immune processes in the context of stroke. We conducted a systematic literatures search in PubMed, Web of Science, Embase, and guideline-specific databases until May 2021 using the following key terms: gut microbiota, stroke, immune, and inflammation.

Long-Term Recovery of the Fecal Microbiome and Metabolome of Dogs with Steroid-Responsive Enteropathy

The long-term impact of treatment of dogs with steroid-responsive enteropathy (SRE) on the fecal microbiome and metabolome has not been investigated. Therefore, this study aimed to evaluate the fecal microbiome and metabolome of dogs with SRE before, during, and following treatment with standard immunosuppressive therapy and an elimination diet. We retrospectively selected samples from 9 dogs with SRE enrolled in a previous clinical trial, which received treatment for 8 weeks, and had achieved remission as indicated by the post-treatment clinical scores. Long-term (1 year) samples were obtained from a subset (5/9) of dogs. Samples from 13 healthy dogs were included as controls (HC). We evaluated the microbiome using 16S rRNA sequencing and qPCR. To evaluate the recovery of gut function, we measured fecal metabolites using an untargeted approach. While improvement was observed for some bacterial taxa after 8 weeks of treatment, several bacterial taxa remained significantly different from HC. Seventy-five metabolites were altered in dogs with SRE, including increased fecal amino acids and vitamins, suggesting malabsorption as a component of SRE. One year after treatment, however, all bacterial species were evaluated by qPCR and 16S rRNA gene sequencing, and all but thirteen metabolites were no longer different from healthy controls.

The effects of signalment, diet, geographic location, season, and colitis associated with antimicrobial use or Salmonella infection on the fecal microbiome of horses

BACKGROUND

The fecal microbiome of healthy horses may be influenced by signalment, diet, environmental factors, and disease.

OBJECTIVES

To assess the effects of age, breed, sex, geographic location, season, diet, and colitis caused by antibiotic use (antimicrobial-associated diarrhea [AAD]) and Salmonella infection on fecal microbiota.

ANIMALS

Healthy horses (n = 80) were sampled from nonhospital environments across multiple geographical locations in the United States. Horses with AAD (n = 14) were defined as those that developed diarrhea secondary to antimicrobial use. Horses with Salmonella infection (n = 12) were presented with spontaneous onset of colitis and subsequently tested positive on Salmonella quantitative polymerase chain reaction. All horses were >1 year of age and stratified by a dietary scale that included forages (pasture and hay) and concentrates grouped by percentage of fiber and amount.

METHODS

Illumina sequencing of 16S rRNA genes was performed on fecal DNA.

RESULTS

Healthy horses fed higher amounts of grain clustered separately from those fed lower amounts of grain (analysis of similarities [ANOSIM], R = 0.356-0.385, Q = 0.002). Horses with AAD and Salmonella had decreased richness and evenness compared to healthy horses (P < .05). Univariable analysis of the 3 groups identified increases in Bacteroidetes (Q = 0.002) and Protebacteria (Q = 0.001) and decreases in Verrucomicrobia (Q = 0.001) in AAD horses whereas Salmonella horses had less Firmicutes (Q = 0.001) when compared to healthy horses.

CONCLUSIONS AND CLINICAL IMPORTANCE

Although the amount of grain in the diet had some impact on the fecal microbiome, colitis had a significantly larger influence. Horses with ADD have a more severe dysbiosis than do horses with Salmonella.

Inflammation increases the development of depression behaviors in male rats after spinal cord injury

Following spinal cord injury, 18-26% of patients are diagnosed with depressive disorders, compared to 8-12% in the general population. As increased inflammation strongly correlates with depression in both animal and human studies, we hypothesized that the immune activation inherent to SCI could increase depression-like behavior. Thus, we proposed that reducing immune activation with minocycline, a microglial inhibitor, would decrease depression-like behavior following injury. Male Sprague-Dawley rats were given minocycline in their drinking water for 14 days following a moderate, mid-thoracic (T12) spinal contusion. An array of depression-like behaviors (social activity, sucrose preference, forced swim, open field activity) were examined prior to injury as well as on days 9-10, 19-20, and 29-30 post-injury. Peripheral cytokine levels were analyzed in serum collected prior to injury and 10 days post-injury. Hierarchical cluster analysis divided subjects into two groups based on behavior: depressed and not-depressed. Depressed subjects displayed lower levels of open field activity and social interaction relative to their not-depressed counterparts. Depressed subjects also showed significantly greater expression of pro-inflammatory cytokines both before and after injury and displayed lower levels of hippocampal neurogenesis than not-depressed subjects. Intriguingly, subjects who later showed depressive behaviors had higher baseline levels of the pro-inflammatory cytokine IL-6, which persisted throughout the duration of the experiment. Minocycline, however, did not affect serum cytokine levels and did not block the development of depression; equal numbers of minocycline versus vehicle-treated subjects appeared in both phenotypic groups. Despite this, these data overall suggest that molecular correlates of inflammation prior to injury could predict the development of depression after a physical stressor.

Di-(2-ethylhexyl) phthalate exposure induces female reproductive toxicity and alters the intestinal microbiota community structure and fecal metabolite profile in mice

Di-(2-ethylhexyl) phthalate (DEHP) is one of the most commonly used plasticizers, and it is widely applied in various plastic products. DEHP is an endocrine-disrupting chemical (EDC) that has been shown to disrupt the function of reproductive system in females. Although many studies have shown that DEHP potentially causes female reproductive toxicity, including depletion of the primordial follicle and decreased sex hormone production, the specific mechanisms by which DEHP affects female reproduction remain unknown. In recent years, research focused on the intestinal flora has provided an idea to eliminate our confusion, and gut bacterial dysbiosis may contribute to female reproductive toxicity. In the present study, the feces of DEHP-exposed mice were collected and analyzed using 16S rRNA amplicon sequencing and untargeted global metabolite profiling of metabolomics. DEHP obviously causes reproductive toxicity, including the ovarian organ coefficient, estradiol level, histological features of the ovary and estrus. Furthermore, DEHP exposure alters the structure of the intestinal microbiota community and fecal metabolite profile in mice, suggesting that the reproductive toxicity may be caused by gut bacterial dysbiosis and altered metabolites, such as changes in the levels of short-chain fatty acid (SCFA). Additionally, it is well known that changes in gut microbiota and fecal metabolites cause inflammation and tissue oxidative stress, expectedly, we found oxidative stress in the ovary and systemic inflammation in DEHP exposed mice. Thus, based on our findings, DEHP exposure may cause gut bacterial dysbiosis and altered metabolite profiles, particularly SCFA profiles, leading to oxidative stress in the ovary and systemic inflammation to ultimately induce female reproductive toxicity.

Alterations in the gut microbiota and metabolite profiles in the context of neuropathic pain

The aim of this study was to explore the relationships among gut microbiota disturbances and serum and spinal cord metabolic disorders in neuropathic pain. 16S rDNA amplicon sequencing and serum and spinal cord metabolomics were used to identify alterations in the microbiota and metabolite profiles in the sham rats and the chronic constriction injury (CCI) model rats. Correlations between the abundances of gut microbiota components at the genus level, the levels of serum metabolites, and pain-related behavioural parameters were analysed. Ingenuity pathway analysis (IPA) was applied to analyse the interaction networks of the differentially expressed serum metabolites. First, we found that the composition of the gut microbiota was different between rats with CCI-induced neuropathic pain and sham controls. At the genus level, the abundances of Helicobacter, Phascolarctobacterium, Christensenella, Blautia, Streptococcus, Rothia and Lactobacillus were significantly increased, whereas the abundances of Ignatzschineria, Butyricimonas, Escherichia, AF12, and Corynebacterium were significantly decreased. Additionally, 72 significantly differentially expressed serum metabolites and 17 significantly differentially expressed spinal cord metabolites were identified between the CCI rats and the sham rats. Finally, correlation analysis showed that changes in the gut microbiota was significantly correlated with changes in serum metabolite levels, suggesting that dysbiosis of the gut microbiota is an important factor in modulating metabolic disturbances in the context of neuropathic pain. In conclusion, our research provides a novel perspective on the potential roles of the gut microbiota and related metabolites in neuropathic pain.

The Gut Microbiome of Dogs and Cats, and the Influence of Diet

The gut microbiome is a functional organ, and responds metabolically to the nutrient composition within the diet. Fiber, starch, and protein content have strong effects on the microbiome composition, and changes in these nutrient profiles can induce rapid shifts. Due to functional redundancy of bacteria within microbial communities, important metabolites for health can be produced by different bacteria. Microbiome alterations associated with disease are of greater magnitude than those seen in healthy dogs on different diets. Dietary changes, addition of prebiotics, and probiotics, can be beneficial to improve microbial diversity and to normalize metabolite production in diseased dogs.

Sex differences in stroke outcome correspond to rapid and severe changes in gut permeability in adult Sprague-Dawley rats

BACKGROUND

Sex differences in experimental stroke outcomes are well documented, such that adult males have a greater infarct volume, increased stroke-induced mortality, and more severe sensory-motor impairment. Based on recent evidence that the gut is an early responder to stroke, the present study tested the hypothesis that sex differences in stroke severity will be accompanied by rapid and greater permeability of the gut-blood barrier and gut dysbiosis in males as compared to females.

METHOD

Male and female Sprague-Dawley rats (5-7 months of age) were subject to endothelin (ET)-1-induced middle cerebral artery occlusion (MCAo). Sensory-motor tests were conducted pre- and 2 days after MCAo. Gut permeability was assessed in serum samples using biomarkers of gut permeability as well as functional assays using size-graded dextrans. Histological analysis of the gut was performed with H&E staining, periodic acid-Schiff for mucus, and immunohistochemistry for the tight junction protein, ZO-1. Fecal samples obtained pre- and post-stroke were analyzed for bacterial taxa and short-chain fatty acids (SCFAs).

RESULTS

After stroke, males displayed greater mortality, worse sensory-motor deficit, and higher serum levels of proinflammatory cytokines IL-17A, MCP-1, and IL-5 as compared to females. MCAo-induced gut permeability was rapid and severe in males as indicated by dextran extravasation from the gut to the blood in the hyperacute (< 2 h) and early acute (2 days) phase of stroke. This was accompanied by dysmorphology of the gut villi and dysregulation of the tight junction protein ZO-1 in the acute phase. Fecal 16s sequencing showed no differences in bacterial diversity in the acute phase of stroke. Predictive modeling indicated that markers of gut permeability were associated with acute sensory-motor impairment and infarct volume.

CONCLUSIONS

These data show that extensive leakiness of the gut barrier is associated with severe post-stroke disability and suggest that reinforcing this barrier may improve stroke outcomes.

Dysbiosis is one of the risk factor for stroke and cognitive impairment and potential target for treatment

More than 50 million people have various forms of cognitive impairment basically caused by neurodegenerative diseases, such as Alzheimer's, Parkinson's, and cerebrovascular diseases as well as stroke. Often these conditions coexist and exacerbate one another. The damaged area in post-stroke dementia may lead to neurodegenerative lesions. Gut microbiome functions like an endocrine organ by generating bioactive metabolites that can directly or indirectly impact human physiology. An alteration in the composition and function of intestinal flora, i.e. gut dysbiosis, is implicated in neurodegenerative and cerebrovascular diseases. Additionally, gut dysbiosis may accelerate the progression of cognitive impairment. Dysbiosis may result from obesity; metabolic disorders, cardiovascular disease, and sleep disorders, Lack of physical activity is associated with dysbiosis as well. These may coexist in various patterns in older people, enhancing the risk, incidence, and progression of cerebrovascular lesions, neurodegenerative disorders, and cognitive impairment, creating a vicious circle. Recently, it has been reported that several metabolites produced by gut microbiota (e.g., trimethylamine/trimethylamine N-oxide, short-chain fatty acids, secondary bile acids) may be linked to neurodegenerative and cerebrovascular diseases. New treatment modalities, including prebiotic and probiotics, may normalize the gut microbiota composition, change the brain-gut barrier, and decrease the risk of the pathology development. Fecal microbiota transplantation, sometimes in combination with other methods, is used for remodeling and replenishing the symbiotic gut microbiome. This promising field of research is associated with basic findings of bidirectional communication between body organs and gut microbiota that creates new possibilities of pharmacological treatments of many clinical conditions. The authors present the role of gut microbiota in physiology, and the novel therapeutic targets in modulation of intestinal microbiota Personalized therapies based on their personal genome make up could offer benefits by modulating microbiota cross-talk with brain and cardiovascular system. A healthy lifestyle, including pre and probiotic nutrition is generally recommended. Prevention may also be enhanced by correcting gut dysbiosis resulting a reduced risk of post-stroke cognitive impairment including dementia.

Effects of metronidazole on the fecal microbiome and metabolome in healthy dogs

Background

Metronidazole has a substantial impact on the gut microbiome. However, the recovery of the microbiome after discontinuation of administration, and the metabolic consequences of such alterations have not been investigated to date.

Objectives

To describe the impact of 14‐day metronidazole administration, alone or in combination with a hydrolyzed protein diet, on fecal microbiome, metabolome, bile acids (BAs), and lactate production, and on serum metabolome in healthy dogs.

Animals

Twenty‐four healthy pet dogs.

Methods

Prospective, nonrandomized controlled study. Dogs fed various commercial diets were divided in 3 groups: control group (no intervention, G1); group receiving hydrolyzed protein diet, followed by metronidazole administration (G2); and group receiving metronidazole only (G3). Microbiome composition was evaluated with sequencing of 16S rRNA genes and quantitative polymerase chain reaction (qPCR)‐based dysbiosis index. Untargeted metabolomics analysis of fecal and serum samples was performed, followed by targeted assays for fecal BAs and lactate.

Results

No changes were observed in G1, or G2 during diet change. Metronidazole significantly changed microbiome composition in G2 and G3, including decreases in richness (P < .001) and in key bacteria such as Fusobacteria (q < 0.001) that did not fully resolve 4 weeks after metronidazole discontinuation. Fecal dysbiosis index was significantly increased (P < .001). Those changes were accompanied by increased fecal total lactate (P < .001), and decreased secondary BAs deoxycholic acid and lithocholic acid (P < .001).

Conclusion and Clinical Importance

Our results indicate a minimum 4‐week effect of metronidazole on fecal microbiome and metabolome, supporting a cautious approach to prescription of metronidazole in dogs.

The alteration of gut microbiome and metabolism in amyotrophic lateral sclerosis patients

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease accompanied with severe paralysis or even death, while the pathogenesis of ALS is still unclear and no effective therapy exists. The accumulating evidence has indicated the association between gut microbiota and various neurological diseases. Thus, to explore the potential role of gut microbiome in ALS, 20 patients diagnosed with probable or definite ALS and 20 healthy controls were enrolled and their fecal excrements were collected. The analysis of fecal community diversity with 16S rDNA sequencing showed an obvious change in microbial structure of ALS patients, where Bacteroidetes at the phylum level and several microbes at the genus level were up-regulated, while Firmicutes at the phylum level and Megamonas at the genus level were down-regulated compared to healthy controls. Additionally, decreased gene function associated with metabolic pathways was observed in ALS patients. The metagenomics further demonstrated the discrepancies in microflora at the species level and relevant metabolites thereof were also revealed when combined with metabolomics. In conclusion, the altered composition of the gut microbiota and metabolic products in ALS patients provided deeper insights into the pathogenesis of ALS, and these biomarkers might be established as potential therapeutic targets which deserve further exploration.

Distinct Commensal Bacterial Signature in the Gut Is Associated With Acute and Long-Term Protection From Ischemic Stroke

Background and Purpose- Commensal gut bacteria have a profound impact on stroke pathophysiology. Here, we investigated whether modification of the microbiota influences acute and long-term outcome in mice subjected to stroke. Methods- C57BL/6 male mice received a cocktail of antibiotics or single antibiotic. After 4 weeks, fecal bacterial density of the 16S rRNA gene was quantitated by qPCR, and phylogenetic classification was obtained by 16S rRNA gene sequencing. Infarct volume and hemispheric volume loss were measured 3 days and 5 weeks after middle cerebral artery occlusion, respectively. Neurological deficits were tested by the Tape Test and the open field test. Results- Mice treated with a cocktail of antibiotics displayed a significant reduction of the infarct volume in the acute phase of stroke. The neuroprotective effect was abolished in mice recolonized with a wild-type microbiota. Single antibiotic treatment with either ampicillin or vancomycin, but not neomycin, was sufficient to reduce the infarct volume and improved motorsensory function 3 days after stroke. This neuroprotective effect was correlated with a specific microbial population rather than the total bacterial density. In particular, random forest analysis trained for the severity of the brain damage revealed that Bacteroidetes S24.7 and the enzymatic pathway for aromatic metabolism discriminate between large versus small infarct size. Additionally, the microbiota signature in the ampicillin-treated mice was associated with a reduced gut inflammation, long-term favorable outcome shown by an amelioration of the stereotypic behavior, and a reduction of brain tissue loss in comparison to control and was predictive of a regulation of short-chain fatty acids and tryptophan pathways. Conclusions- The findings highlight the importance of the intestinal microbiota in short- and long-term outcomes of ischemic stroke and raises the possibility that targeted modification of the microbiome associated with specific microbial enzymatic pathways may provide a preventive strategy in patients at high risk for stroke. Visual Overview- An online visual overview is available for this article.