Evidence that the loss of colonic anti-microbial peptides may promote dysbiotic Gram-negative inflammaging-associated bacteria in aging mice

Introduction: Aging studies in humans and mice have played a key role in understanding the intestinal microbiome and an increased abundance of "inflammaging" Gram-negative (Gn) bacteria. The mechanisms underlying this inflammatory profile in the aging microbiome are unknown. We tested the hypothesis that an aging-related decrease in colonic crypt epithelial cell anti-microbial peptide (AMP) gene expression could promote colonic microbiome inflammatory Gn dysbiosis and inflammaging. Methods: As a model of aging, C57BL/6J mice fecal (colonic) microbiota (16S) and isolated colonic crypt epithelial cell gene expression (RNA-seq) were assessed at 2 months (mth) (human: 18 years old; yo), 15 mth (human: 50 yo), and 25 mth (human: 84 yo). Informatics examined aging-related microbial compositions, differential colonic crypt epithelial cell gene expressions, and correlations between colonic bacteria and colonic crypt epithelial cell gene expressions. Results: Fecal microbiota exhibited significantly increased relative abundances of pro-inflammatory Gn bacteria with aging. Colonic crypt epithelial cell gene expression analysis showed significant age-related downregulation of key AMP genes that repress the growth of Gn bacteria. The aging-related decrease in AMP gene expressions is significantly correlated with an increased abundance in Gn bacteria (dysbiosis), loss of colonic barrier gene expression, and senescence- and inflammation-related gene expression. Conclusion: This study supports the proposed model that aging-related loss of colonic crypt epithelial cell AMP gene expression promotes increased relative abundances of Gn inflammaging-associated bacteria and gene expression markers of colonic inflammaging. These data may support new targets for aging-related therapies based on intestinal genes and microbiomes.

The Human Microbiome and Its Role in Musculoskeletal Disorders

Musculoskeletal diseases (MSDs) are characterized as injuries and illnesses that affect the musculoskeletal system. MSDs affect every population worldwide and are associated with substantial global burden. Variations in the makeup of the gut microbiota may be related to chronic MSDs. There is growing interest in exploring potential connections between chronic MSDs and variations in the composition of gut microbiota. The human microbiota is a complex community consisting of viruses, archaea, bacteria, and eukaryotes, both inside and outside of the human body. These microorganisms play crucial roles in influencing human physiology, impacting metabolic and immunological systems in health and disease. Different body areas host specific types of microorganisms, with facultative anaerobes dominating the gastrointestinal tract (able to thrive with or without oxygen), while strict aerobes prevail in the nasal cavity, respiratory tract, and skin surfaces (requiring oxygen for development). Together with the immune system, these bacteria have coevolved throughout time, forming complex biological relationships. Changes in the microbial ecology of the gut may have a big impact on health and can help illnesses develop. These changes are frequently impacted by lifestyle choices and underlying medical disorders. The potential for safety, expenses, and efficacy of microbiota-based medicines, even with occasional delivery, has attracted interest. They are, therefore, a desirable candidate for treating MSDs that are chronic and that may have variable progression patterns. As such, the following is a narrative review to address the role of the human microbiome as it relates to MSDs.

Colonic Epithelial Circadian Disruption Worsens Dextran Sulfate Sodium-Induced Colitis

BACKGROUND

Disruption of central circadian rhythms likely mediated by changes in microbiota and a decrease in gut-derived metabolites like short chain fatty acids (SCFAs) negatively impacts colonic barrier homeostasis. We aimed to explore the effects of isolated peripheral colonic circadian disruption on the colonic barrier in a mouse model of colitis and explore the mechanisms, including intestinal microbiota community structure and function.

METHODS

Colon epithelial cell circadian rhythms were conditionally genetically disrupted in mice: TS4Cre-BMAL1lox (cBMAL1KO) with TS4Cre as control animals. Colitis was induced through 5 days of 2% dextran sulfate sodium (DSS). Disease activity index and intestinal barrier were assessed, as were fecal microbiota and metabolites.

RESULTS

Colitis symptoms were worse in mice with peripheral circadian disruption (cBMAL1KO). Specifically, the disease activity index and intestinal permeability were significantly higher in circadian-disrupted mice compared with control animals (TS4Cre) (P < .05). The worsening of colitis appears to be mediated, in part, through JAK (Janus kinase)-mediated STAT3 (signal transducer and activator of transcription 3), which was significantly elevated in circadian-disrupted (cBMAL1KO) mice treated with DSS (P < .05). Circadian-disrupted (cBMAL1KO) mice also had decreased SCFA metabolite concentrations and decreased relative abundances of SCFA-producing bacteria in their stool when compared with control animals (TS4Cre).

CONCLUSIONS

Disruption of intestinal circadian rhythms in colonic epithelial cells promoted more severe colitis, increased inflammatory mediators (STAT3 [signal transducer and activator of transcription 3]), and decreased gut microbiota-derived SCFAs compared with DSS alone. Further investigation elucidating the molecular mechanisms behind these findings could provide novel circadian directed targets and strategies in the treatment of inflammatory bowel disease.

An open label, non-randomized study assessing a prebiotic fiber intervention in a small cohort of Parkinson's disease participants

A pro-inflammatory intestinal microbiome is characteristic of Parkinson's disease (PD). Prebiotic fibers change the microbiome and this study sought to understand the utility of prebiotic fibers for use in PD patients. The first experiments demonstrate that fermentation of PD patient stool with prebiotic fibers increased the production of beneficial metabolites (short chain fatty acids, SCFA) and changed the microbiota demonstrating the capacity of PD microbiota to respond favorably to prebiotics. Subsequently, an open-label, non-randomized study was conducted in newly diagnosed, non-medicated (n = 10) and treated PD participants (n = 10) wherein the impact of 10 days of prebiotic intervention was evaluated. Outcomes demonstrate that the prebiotic intervention was well tolerated (primary outcome) and safe (secondary outcome) in PD participants and was associated with beneficial biological changes in the microbiota, SCFA, inflammation, and neurofilament light chain. Exploratory analyses indicate effects on clinically relevant outcomes. This proof-of-concept study offers the scientific rationale for placebo-controlled trials using prebiotic fibers in PD patients. ClinicalTrials.gov Identifier: NCT04512599.

Alcohol use disorder as a potential risk factor for COVID-19 severity: A narrative review

In Dec. 2019-January 2020, a pneumonia illness originating in Wuhan, China, designated as coronavirus disease 2019 (COVID-19) was shown to be caused by a novel RNA coronavirus designated as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). People with advanced age, male sex, and/or underlying health conditions (obesity, type 2 diabetes, cardiovascular disease, hypertension, chronic kidney disease, and chronic lung disease) are especially vulnerable to severe COVID-19 symptoms and death. These risk factors impact the immune system and are also associated with poor health, chronic illness, and shortened longevity. However, a large percent of patients without these known risk factors also develops severe COVID-19 disease that can result in death. Thus, there must exist risk factors that promote exaggerated inflammatory and immune response to the SARS-CoV-2 virus leading to death. One such risk factor may be alcohol misuse and alcohol use disorder because these can exacerbate viral lung infections like SARS, influenza, and pneumonia. Thus, it is highly plausible that alcohol misuse is a risk factor for either increased infection rate when individuals are exposed to SARS-CoV-2 virus and/or more severe COVID-19 in infected patients. Alcohol use is a well-known risk factor for lung diseases and ARDS in SARS patients. We propose that alcohol has three key pathogenic elements in common with other COVID-19 severity risk factors: namely, inflammatory microbiota dysbiosis, leaky gut, and systemic activation of the NLRP3 inflammasome. We also propose that these three elements represent targets for therapy for severe COVID-19.

The SARS-CoV-2 S1 Spike Protein Promotes MAPK and NF-kB Activation in Human Lung Cells and Inflammatory Cytokine Production in Human Lung and Intestinal Epithelial Cells

The coronavirus disease 2019 (COVID-19) pandemic began in January 2020 in Wuhan, China, with a new coronavirus designated SARS-CoV-2. The principal cause of death from COVID-19 disease quickly emerged as acute respiratory distress syndrome (ARDS). A key ARDS pathogenic mechanism is the “Cytokine Storm”, which is a dramatic increase in inflammatory cytokines in the blood. In the last two years of the pandemic, a new pathology has emerged in some COVID-19 survivors, in which a variety of long-term symptoms occur, a condition called post-acute sequelae of COVID-19 (PASC) or “Long COVID”. Therefore, there is an urgent need to better understand the mechanisms of the virus. The spike protein on the surface of the virus is composed of joined S1–S2 subunits. Upon S1 binding to the ACE2 receptor on human cells, the S1 subunit is cleaved and the S2 subunit mediates the entry of the virus. The S1 protein is then released into the blood, which might be one of the pivotal triggers for the initiation and/or perpetuation of the cytokine storm. In this study, we tested the hypothesis that the S1 spike protein is sufficient to activate inflammatory signaling and cytokine production, independent of the virus. Our data support a possible role for the S1 spike protein in the activation of inflammatory signaling and cytokine production in human lung and intestinal epithelial cells in culture. These data support a potential role for the SARS-CoV-2 S1 spike protein in COVID-19 pathogenesis and PASC.

Impact of alcohol-induced intestinal microbiota dysbiosis in a rodent model of Alzheimer's disease

Introduction: Alzheimer's disease (AD) is a devastating neurodegenerative disorder. While genetics are important in the development of AD, environment and lifestyle are also important factors influencing AD. One such lifestyle factor is alcohol consumption. Unhealthy and excessive chronic alcohol consumption is associated with a greater risk of all types of dementia, especially AD. Alcohol consumption has numerous effects on the body, including alterations to the intestinal microbiota (dysbiosis) and intestinal barrier dysfunction (leakiness and intestinal hyperpermeability), with evidence indicating that inflammation resulting from dysbiosis and barrier dysfunction can promote neuroinflammation impacting brain structure and function. Objective: This study sought to determine the impact of alcohol-induced dysbiosis and barrier dysfunction on AD-like behavior and brain pathology using a transgenic rodent model of AD (3xTg-AD). Methods: Alcohol (20%) was administered to 3xTg-AD mice in the drinking water for 20 weeks. Intestinal (stool) microbiota, intestinal barrier permeability, systemic inflammation (IL-6), behavior, and AD pathology (phosphorylated tau and β-amyloid), and microglia were examined. Results: Alcohol consumption changed the intestinal microbiota community (dysbiosis) and increased intestinal barrier permeability in both control and 3xTg-AD mice (oral/urine sugar test and lipopolysaccharide-binding protein (LBP)). However, alcohol consumption did not influence serum IL-6, behavior, or β-amyloid, phosphorylated tau, or microglia in 3xTg-AD mice. Important differences in genotype and sex were noted. Conclusion: Alcohol-induced microbiota dysbiosis and intestinal barrier dysfunction did not exacerbate behavior or AD-like brain pathology in the 3xTg-AD mouse model of AD which could, in part, be the result of a lack of systemic inflammation.

Abnormal intestinal milieu in posttraumatic stress disorder is not impacted by treatment that improves symptoms

Posttraumatic stress disorder (PTSD) is a psychiatric disorder, resulting from exposure to traumatic events. Current recommended first-line interventions for the treatment of PTSD include evidence-based psychotherapies, such as cognitive processing therapy (CPT). Psychotherapies are effective for reducing PTSD symptoms, but approximately two-thirds of veterans continue to meet diagnostic criteria for PTSD after treatment, suggesting there is an incomplete understanding of what factors sustain PTSD. The intestine can influence the brain and this study evaluated intestinal readouts in subjects with PTSD. Serum samples from controls without PTSD (n = 40) from the Duke INTRuST Program were compared with serum samples from veterans with PTSD (n = 40) recruited from the Road Home Program at Rush University Medical Center. Assessments included microbial metabolites, intestinal barrier, and intestinal epithelial cell function. In addition, intestinal readouts were assessed in subjects with PTSD before and after a 3-wk CPT-based intensive treatment program (ITP) to understand if treatment impacts the intestine. Compared with controls, veterans with PTSD had a proinflammatory intestinal environment including lower levels of microbiota-derived metabolites, such as acetic, lactic, and succinic acid, intestinal barrier dysfunction [lipopolysaccharide (LPS) and LPS-binding protein], an increase in HMGB1, and a concurrent increase in the number of intestinal epithelial cell-derived extracellular vesicles. The ITP improved PTSD symptoms but no changes in intestinal outcomes were noted. This study confirms the intestine is abnormal in subjects with PTSD and suggests that effective treatment of PTSD does not alter intestinal readouts. Targeting beneficial changes in the intestine may be an approach to enhance existing PTSD treatments.NEW & NOTEWORTHY This study confirms an abnormal intestinal environment is present in subjects with PTSD. This study adds to what is already known by examining the intestinal barrier and evaluating the relationship between intestinal readouts and PTSD symptoms and is the first to report the impact of PTSD treatment (which improves symptoms) on intestinal readouts. This study suggests that targeting the intestine as an adjunct approach could improve the treatment of PTSD.

Gut-Brain Communication in Parkinson's Disease: Enteroendocrine Regulation by GLP-1

PURPOSE OF REVIEW

Defective gut-brain communication has recently been proposed as a promoter of neurodegeneration, but mechanisms mediating communication remain elusive. In particular, the Parkinson's disease (PD) phenotype has been associated with both dysbiosis of intestinal microbiota and neuroinflammation. Here, we review recent advances in the PD field that connect these two concepts, providing an explanation based on enteroendocrine signaling from the gut to the brain.

RECENT FINDINGS

There have been several recent accounts highlighting the importance of the microbiota-gut-brain axis in PD. The objective of this review is to discuss the role of the neuroendocrine system in gut-brain communication as it relates to PD pathogenesis, as this system has not been comprehensively considered in prior reviews. The incretin hormone glucagon-like peptide 1 (GLP-1) is secreted by enteroendocrine cells of the intestinal epithelium, and there is evidence that it is neuroprotective in animal models and human subjects with PD. Agonists of GLP-1 receptors used in diabetes appear to be useful for preventing neurodegeneration. New tools and models have enabled us to study regulation of GLP-1 secretion by intestinal microbiota, to understand how this process may be defective in PD, and to develop methods for therapeutically modifying disease development or progression using the enteroendocrine system. GLP-1 secretion by enteroendocrine cells may be a key mediator of neuroprotection in PD, and new findings in this field may offer unique insights into PD pathogenesis and therapeutic strategies.

Intestinal Barrier Dysfunction in the Absence of Systemic Inflammation Fails to Exacerbate Motor Dysfunction and Brain Pathology in a Mouse Model of Parkinson's Disease

Introduction

Parkinson's disease (PD) is the second most common neurodegenerative disease associated with aging. PD patients have systemic and neuroinflammation which is hypothesized to contribute to neurodegeneration. Recent studies highlight the importance of the gut-brain axis in PD pathogenesis and suggest that gut-derived inflammation can trigger and/or promote neuroinflammation and neurodegeneration in PD. However, it is not clear whether microbiota dysbiosis, intestinal barrier dysfunction, or intestinal inflammation (common features in PD patients) are primary drivers of disrupted gut-brain axis in PD that promote neuroinflammation and neurodegeneration.

Objective

To determine the role of microbiota dysbiosis, intestinal barrier dysfunction, and colonic inflammation in neuroinflammation and neurodegeneration in a genetic rodent model of PD [α-synuclein overexpressing (ASO) mice].

Methods

To distinguish the role of intestinal barrier dysfunction separate from inflammation, low dose (1%) dextran sodium sulfate (DSS) was administered in cycles for 52 days to ASO and control mice. The outcomes assessed included intestinal barrier integrity, intestinal inflammation, stool microbiome community, systemic inflammation, motor function, microglial activation, and dopaminergic neurons.

Results

Low dose DSS treatment caused intestinal barrier dysfunction (sugar test, histological analysis), intestinal microbiota dysbiosis, mild intestinal inflammation (colon shortening, elevated MPO), but it did not increase systemic inflammation (serum cytokines). However, DSS did not exacerbate motor dysfunction, neuroinflammation (microglial activation), or dopaminergic neuron loss in ASO mice.

Conclusion

Disruption of the intestinal barrier without overt intestinal inflammation is not associated with worsening of PD-like behavior and pathology in ASO mice.

Deep nasal sinus cavity microbiota dysbiosis in Parkinson's disease

Olfactory dysfunction is a pre-motor symptom of Parkinson’s disease (PD) that appears years prior to diagnosis and can affect quality of life in PD. Changes in microbiota community in deep nasal cavity near the olfactory bulb may trigger the olfactory bulb-mediated neuroinflammatory cascade and eventual dopamine loss in PD. To determine if the deep nasal cavity microbiota of PD is significantly altered in comparison to healthy controls, we characterized the microbiota of the deep nasal cavity using 16S rRNA gene amplicon sequencing in PD subjects and compared it to that of spousal and non-spousal healthy controls. Correlations between microbial taxa and PD symptom severity were also explored. Olfactory microbial communities of PD individuals were more similar to those of their spousal controls than to non-household controls. In direct comparison of PD and spousal controls and of PD and non-spousal controls, significantly differently abundant taxa were identified, and this included increased relative abundance of putative opportunistic-pathobiont species such as Moraxella catarrhalis. M. catarrhalis was also significantly correlated with more severe motor scores in PD subjects. This proof-of-concept study provides evidence that potential pathobionts are detected in the olfactory bulb and that a subset of changes in the PD microbiota community could be a consequence of unique environmental factors associated with PD living. We hypothesize that an altered deep nasal microbiota, characterized by a putative pro-inflammatory microbial community, could trigger neuroinflammation in PD.

Dietary Regulation of Gut-Brain Axis in Alzheimer's Disease: Importance of Microbiota Metabolites

Alzheimer's disease (AD) is a neurodegenerative disease that impacts 45 million people worldwide and is ranked as the 6th top cause of death among all adults by the Centers for Disease Control and Prevention. While genetics is an important risk factor for the development of AD, environment and lifestyle are also contributing risk factors. One such environmental factor is diet, which has emerged as a key influencer of AD development/progression as well as cognition. Diets containing large quantities of saturated/trans-fats, refined carbohydrates, limited intake of fiber, and alcohol are associated with cognitive dysfunction while conversely diets low in saturated/trans-fats (i.e., bad fats), high mono/polyunsaturated fats (i.e., good fats), high in fiber and polyphenols are associated with better cognitive function and memory in both humans and animal models. Mechanistically, this could be the direct consequence of dietary components (lipids, vitamins, polyphenols) on the brain, but other mechanisms are also likely to be important. Diet is considered to be the single greatest factor influencing the intestinal microbiome. Diet robustly influences the types and function of micro-organisms (called microbiota) that reside in the gastrointestinal tract. Availability of different types of nutrients (from the diet) will favor or disfavor the abundance and function of certain groups of microbiota. Microbiota are highly metabolically active and produce many metabolites and other factors that can affect the brain including cognition and the development and clinical progression of AD. This review summarizes data to support a model in which microbiota metabolites influence brain function and AD.

Attenuated Postprandial GLP-1 Response in Parkinson's Disease

The incretin hormone glucagon-like peptide 1 (GLP-1) has neuroprotective effects in animal models of Parkinson’s disease (PD), and GLP-1 receptor agonists are associated with clinical improvements in human PD patients. GLP-1 is produced and secreted by intestinal L-cells in response to consumption of a meal. Specifically, intestinal microbiota produce short chain fatty acids (SCFA) which, in turn, promote secretion of GLP-1 into the systemic circulation, from which it can enter the brain. Our group and others have reported that PD patients have an altered intestinal microbial community that produces less SCFA compared to age-matched controls. In this report, we demonstrate that PD patients have diminished GLP-1 secretion in response to a meal compared to their household controls. Peak postprandial GLP-1 levels did not correlate with PD disease severity, motor function, or disease duration. These data provide the scientific rationale for future studies designed to elucidate the role of GLP-1 in the pathogenesis of PD and test the potential utility of GLP-1-directed therapies.

Plasma Markers of Disrupted Gut Permeability in Severe COVID-19 Patients

A disruption of the crosstalk between the gut and the lung has been implicated as a driver of severity during respiratory-related diseases. Lung injury causes systemic inflammation, which disrupts gut barrier integrity, increasing the permeability to gut microbes and their products. This exacerbates inflammation, resulting in positive feedback. We aimed to test whether severe Coronavirus disease 2019 (COVID-19) is associated with markers of disrupted gut permeability. We applied a multi-omic systems biology approach to analyze plasma samples from COVID-19 patients with varying disease severity and SARS-CoV-2 negative controls. We investigated the potential links between plasma markers of gut barrier integrity, microbial translocation, systemic inflammation, metabolome, lipidome, and glycome, and COVID-19 severity. We found that severe COVID-19 is associated with high levels of markers of tight junction permeability and translocation of bacterial and fungal products into the blood. These markers of disrupted intestinal barrier integrity and microbial translocation correlate strongly with higher levels of markers of systemic inflammation and immune activation, lower levels of markers of intestinal function, disrupted plasma metabolome and glycome, and higher mortality rate. Our study highlights an underappreciated factor with significant clinical implications, disruption in gut functions, as a potential force that may contribute to COVID-19 severity.

Circadian misalignment by environmental light/dark shifting causes circadian disruption in colon

BACKGROUND

Physiological circadian rhythms (CRs) are complex processes with 24-hour oscillations that regulate diverse biological functions. Chronic weekly light/dark (LD) shifting (CR disruption; CRD) in mice results in colonic hyperpermeability. However, the mechanisms behind this phenomenon are incompletely understood. One potential innovative in vitro method to study colonic CRs are colon organoids. The goals of this study were to utilize circadian clock gene Per2 luciferase reporter (Per2::Luc) mice to measure the effects of chronic LD shifting on colonic tissue circadian rhythmicity ex vivo and to determine if organoids made from shifted mice colons recapitulate the in vivo phenotype.

METHODS

Non-shifted (NS) and shifted (S) BL6 Per2::Luc mice were compared after a 22-week experiment. NS mice had a standard 12h light/12h dark LD cycle throughout. S mice alternated 12h LD patterns weekly, with light from 6am-6pm one week followed by shifting light to 6pm-6am the next week for 22 weeks. Mice were tested for intestinal permeability while colon tissue and organoids were examined for CRs of bioluminescence and proteins of barrier function and cell fate.

RESULTS

There was no absolute difference in NS vs. S 24h circadian period or phase. However, chronic LD shifting caused Per2::Luc S mice colon tissue to exhibit significantly greater variability in both the period and phase of Per2::Luc rhythms than NS mice colon tissue and organoids. Chronic LD shifting also resulted in increased colonic permeability of the Per2::Luc mice as well as decreased protein markers of intestinal permeability in colonic tissue and organoids from shifted Per2:Luc mice.

CONCLUSIONS

Our studies support a model in which chronic central circadian disruption by LD shifting alters the circadian phenotype of the colon tissue and results in colon leakiness and loss of colonic barrier function. These CRD-related changes are stably expressed in colon stem cell derived organoids from CRD mice.

Systemic brain derived neurotrophic factor but not intestinal barrier integrity is associated with cognitive decline and incident Alzheimer's disease

The inflammatory hypothesis posits that sustained neuroinflammation is sufficient to induce neurodegeneration and the development of Alzheimer's disease (AD) and Alzheimer's dementia. One potential source of inflammation is the intestine which harbors pro-inflammatory microorganisms capable of promoting neuroinflammation. Systemic inflammation is robustly associated with neuroinflammation as well as low levels of brain derived neurotrophic factor (BDNF) in the systemic circulation and brain. Thus, in this pilot study, we tested the hypothesis that intestinal barrier dysfunction precedes risk of death, incident AD dementia and MCI, cognitive impairment and neuropathology. Serum BDNF was associated with changes in global cognition, working memory, and perceptual speed but not risk of death, incident AD dementia, incident MCI, or neuropathology. Neither of the markers of intestinal barrier integrity examined, including lipopolysaccharide binding protein (LBP) nor intestinal fatty acid binding protein (IFABP), were associated with risk of death, incident AD dementia, incident mild cognitive impairment (MCI), change in cognition (global or domains), or neuropathology. Taken together, the data in this pilot study suggest that intestinal barrier dysfunction does not precede diagnosis of AD or MCI, changes in cognition, or brain pathology. However, since MCI and AD are related to global cognition, the findings with BDNF and the contiguous cognitive measures suggest low power with the trichotomous cognitive status measures. Future studies with larger sample sizes are necessary to further investigate the results from this pilot study.

Disrupted Circadian Rest-Activity Cycles in Inflammatory Bowel Disease Are Associated With Aggressive Disease Phenotype, Subclinical Inflammation, and Dysbiosis

Patients with inflammatory bowel disease (IBD)-Crohn's disease (CD), and ulcerative colitis (UC), have poor sleep quality. Sleep and multiple immunologic and gastrointestinal processes in the body are orchestrated by the circadian clock, and we recently reported that a later category or chronotype of the circadian clock was associated with worse IBD specific outcomes. The goal of this study was to determine if circadian misalignment by rest-activity cycles is associated with markers of aggressive disease, subclinical inflammation, and dysbiosis in IBD. A total of 42 patients with inactive but biopsy-proven CD or UC and 10 healthy controls participated in this prospective cohort study. Subjects were defined as having an aggressive IBD disease history (steroid dependence, use of biologic or immunomodulator, and/or surgery) or non-aggressive history. All participants did two weeks of wrist actigraphy, followed by measurement of intestinal permeability and stool microbiota. Wrist actigraphy was used to calculate circadian markers of rest-activity- interdaily stability (IS), intradaily variability (IV), and relative amplitude (RA). Aggressive IBD history was associated with decrease rest-activity stability (IS) and increased fragmentation compared to non-aggressive IBD and health controls at 0.39 ±.15 vs. 0.51 ± 0.10 vs. 0.55 ± 0.09 (P < 0.05) and 0.83 ± 0.20 vs. 0.72 ± 0.14 (P < 0.05) but not HC at 0.72 ± 0.14 (P = 0.08); respectively. There was not a significant difference in RA by IBD disease history. Increased intestinal permeability and increased TNF-α levels correlated with an increased rest activity fragmentation (IV) at R = 0.35, P < 0.05 and R = 0.37, P < 0.05, respectively; and decreased rest-activity amplitude (RA) was associated with increased stool calprotectin at R = 0.40, P < 0.05. Analysis of intestinal microbiota showed a significant decrease in commensal butyrate producing taxa and increased pro-inflammatory bacteria with disrupted rest-activity cycles. In this study, different components of circadian misalignment by rest-activity cycles were associated with a more aggressive IBD disease history, increased intestinal permeability, stool calprotectin, increased pro-inflammatory cytokines, and dysbiosis. Wrist activity allows for an easy non-invasive assessment of circadian activity which may be an important biomarker of inflammation in IB.

The gut microbiota may be a novel pathogenic mechanism in loosening of orthopedic implants in rats

Particles released from implants cause inflammatory bone loss, which is a key factor in aseptic loosening, the most common reason for joint replacement failure. With the anticipated increased incidence of total joint replacement in the next decade, implant failure will continue to burden patients. The gut microbiome is increasingly recognized as an important factor in bone physiology, however, its role in implant loosening is currently unknown. We tested the hypothesis that implant loosening is associated with changes in the gut microbiota in a preclinical model. When the particle challenge caused local joint inflammation, decreased peri-implant bone volume, and decreased implant fixation, the gut microbiota was affected. When the particle challenge did not cause this triad of local effects, the gut microbiota was not affected. Our results suggest that cross-talk between these compartments is a previously unrecognized mechanism of failure following total joint replacement.

Single-Arm, Non-randomized, Time Series, Single-Subject Study of Fecal Microbiota Transplantation in Multiple Sclerosis

Emerging evidence suggests intestinal microbiota as a central contributing factor to the pathogenesis of Relapsing-Remitting-Multiple-Sclerosis (RRMS). This novel RRMS study evaluated the impact of fecal-microbiota-transplantation (FMT) on a broad array of physiological/clinical outcomes using deep metagenome sequencing of fecal microbiome. FMT interventions were associated with increased abundances of putative beneficial stool bacteria and short-chain-fatty-acid metabolites, which were associated with increased/improved serum brain-derived-neurotrophic-factor levels and gait/walking metrics. This proof-of-concept single-subject longitudinal study provides evidence of potential importance of intestinal microbiota in the pathogenesis of MS, and scientific rationale to help design future randomized controlled trials assessing FMT in RRMS patients.

Alcohol-Induced Immune Dysregulation in the Colon Is Diurnally Variable

Introduction

Alcohol increases the risk of colon cancer. Colonic inflammation mediates the effects of alcohol on colon carcinogenesis. Circadian rhythm disruption enhances the alcohol's effect on colonic inflammation and cancer.

Objective

Here, we investigate the diurnal variation of lymphocyte infiltration in the colonic mucosa in response to alcohol.

Methods

Sixty C57BL6/J mice were fed a chow diet, and gavaged with alcohol at a specific time once per day for 3 consecutive days. Immunohistochemistry and immunofluorescence staining were used to quantify total, effector, and regulatory T cells in the colon. Student's t test, one-way ANOVA, and two-way ANOVA were used to determine significance.

Results

Following the alcohol binge, the composition of immune T cell subsets in the mouse colon was time-dependent. Alcohol did not alter the total number of CD3⁺ T cells. However, upon alcohol treatment, T-bet⁺ T helper 1 (Th1) cells appeared to dominate the T cell population following a reduction in Foxp3⁺ regulatory T cell (Treg) numbers. Depletion of Tregs was time-dependent, and their numbers were dramatically reduced when alcohol was administered during the rest phase. A reduction in Tregs significantly increased the Th1/Treg ratio, resulting in a more proinflammatory milieu.

Conclusions

Alcohol enhanced the proinflammatory profile in the colon mucosa, as demonstrated by a higher T-bet⁺/Foxp3⁺ ratio, especially during the rest phase. These findings may partly account for the interaction of circadian rhythm disruption with alcohol in colon inflammation and cancer.

Diet in Parkinson's Disease: Critical Role for the Microbiome

Background: Parkinson's disease (PD) is the most common movement disorder affecting up to 1% of the population above the age of 60 and 4–5% of those above the age of 85. Little progress has been made on efforts to prevent disease development or halt disease progression. Diet has emerged as a potential factor that may prevent the development or slow the progression of PD. In this review, we discuss evidence for a role for the intestinal microbiome in PD and how diet-associated changes in the microbiome may be a viable approach to prevent or modify disease progression.

Methods: We reviewed studies demonstrating that dietary components/foods were related to risk for PD. We reviewed evidence for the dysregulated intestinal microbiome in PD patients including abnormal shifts in the intestinal microbiota composition (i.e., dysbiosis) characterized by a loss of short chain fatty acid (SCFA) bacteria and increased lipopolysaccharide (LPS) bacteria. We also examined several candidate mechanisms by which the microbiota can influence PD including the NLRP3 inflammasome, insulin resistance, mitochondrial function, vagal nerve signaling.

Results: The PD-associated microbiome is associated with decreased production of SCFA and increased LPS and it is believed that these changes may contribute to the development or exacerbation of PD. Diet robustly impacts the intestinal microbiome and the Western diet is associated with increased risk for PD whereas the Mediterranean diet (including high intake of dietary fiber) decreases PD risk. Mechanistically this may be the consequence of changes in the relative abundance of SCFA-producing or LPS-containing bacteria in the intestinal microbiome with effects on intestinal barrier function, endotoxemia (i.e., systemic LPS), NLRP3 inflammasome activation, insulin resistance, and mitochondrial dysfunction, and the production of factors such as glucagon like peptide 1 (GLP-1) and brain derived neurotrophic factor (BDNF) as well as intestinal gluconeogenesis.

Conclusions: This review summarizes a model of microbiota-gut-brain-axis regulation of neuroinflammation in PD including several new mechanisms. We conclude with the need for clinical trials in PD patients to test this model for beneficial effects of Mediterranean based high fiber diets.

Abnormal Eating Patterns Cause Circadian Disruption and Promote Alcohol-Associated Colon Carcinogenesis

BACKGROUND & AIMS

Alcohol intake with circadian rhythm disruption (CRD) increases colon cancer risk. We hypothesized that eating during or around physiologic rest time, a common habit in modern society, causes CRD and investigated the mechanisms by which it promotes alcohol-associated colon carcinogenesis.

METHODS

The effect of feeding time on CRD was assessed using B6 mice expressing a fusion protein of PERIOD2 and LUCIFERASE (PER2::LUC) were used to model colon polyposis and to assess the effects of feeding schedules, alcohol consumption, and prebiotic treatment on microbiota composition, short-chain fatty acid levels, colon inflammation, and cancer risk. The relationship between butyrate signaling and a proinflammatory profile was assessed by inactivating the butyrate receptor GPR109A.

RESULTS

Eating at rest (wrong-time eating [WTE]) shifted the phase of the colon rhythm in PER2::LUC mice. In TS4Cre × APClox468 mice, a combination of WTE and alcohol exposure (WTE + alcohol) decreased the levels of short-chain fatty acid-producing bacteria and of butyrate, reduced colonic densities of regulatory T cells, induced a proinflammatory profile characterized by hyperpermeability and an increased mucosal T-helper cell 17/regulatory T cell ratio, and promoted colorectal cancer. Prebiotic treatment improved the mucosal inflammatory profile and attenuated inflammation and cancer. WTE + alcohol-induced polyposis was associated with increased signal transducer and activator of transcription 3 expression. Decreased butyrate signaling activated the epithelial signal transducer and activator of transcription 3 in vitro. The relationship between butyrate signaling and a proinflammatory profile was confirmed in human colorectal cancers using The Cancer Genome Atlas.

CONCLUSIONS

Abnormal timing of food intake caused CRD and interacts with alcohol consumption to promote colon carcinogenesis by inducing a protumorigenic inflammatory profile driven by changes in the colon microbiota and butyrate signaling. Accession number of repository for microbiota sequence data: raw FASTQ data were deposited in the NCBI Sequence Read Archive under project PRJNA523141.

Alcohol Effects on Colon Epithelium are Time-Dependent

BACKGROUND

Alcohol intake increases the risk of developing colon cancer. Circadian disruption promotes alcohol's effect on colon carcinogenesis through unknown mechanisms. Alcohol's metabolites induce DNA damage, an early step in carcinogenesis. We assessed the effect of time of alcohol consumption on markers of tissue damage in the colonic epithelium.

METHODS

Mice were treated by alcohol or phosphate-buffered saline (PBS), at 4-hour intervals for 3 days, and their colons were analyzed for (i) proliferation (Ki67) and antiapoptosis (Bcl-2) markers, (ii) DNA damage (γ-H2AX), and (iii) the major acetaldehyde (AcH)-DNA adduct, N2 -ethylidene-dG. To model circadian disruption, mice were shifted once weekly for 12 h and then were sacrificed at 4-hour intervals. Samples of mice with a dysfunctional molecular clock were analyzed. The dynamics of DNA damage repair from AcH treatment as well as role of xeroderma pigmentosum, complementation group A (XPA) in their repair were studied in vitro.

RESULTS

Proliferation and survival of colonic epithelium have daily rhythmicity. Alcohol induced colonic epithelium proliferation in a time-dependent manner, with a stronger effect during the light/rest period. Alcohol-associated DNA damage also occurred more when alcohol was given at light. Levels of DNA adduct did not vary by time, suggesting rather lower repair efficiency during the light versus dark. XPA gene expression, a key excision repair gene, was time-dependent, peaking at the beginning of the dark. XPA knockout colon epithelial cells were inefficient in repair of the DNA damage induced by alcohol's metabolite.

CONCLUSIONS

Time of day of alcohol intake may be an important determinant of colon tissue damage and carcinogenicity.

Circadian rhythms: a regulator of gastrointestinal health and dysfunction

Circadian rhythms regulate much of gastrointestinal physiology including cell proliferation, motility, digestion, absorption, and electrolyte balance. Disruption of circadian rhythms can have adverse consequences including the promotion of and/or exacerbation of a wide variety of gastrointestinal disorders and diseases. Areas covered: In this review, we evaluate some of the many gastrointestinal functions that are regulated by circadian rhythms and how dysregulation of these functions may contribute to disease. This review also discusses some common gastrointestinal disorders that are known to be influenced by circadian rhythms as well as speculation about the mechanisms by which circadian rhythm disruption promotes dysfunction and disease pathogenesis. We discuss how knowledge of circadian rhythms and the advent of chrono-nutrition, chrono-pharmacology, and chrono-therapeutics might influence clinical practice. Expert opinion: As our knowledge of circadian biology increases, it may be possible to incorporate strategies that take advantage of circadian rhythms and chronotherapy to prevent and/or treat disease.