Scaling of stochastic growth and division dynamics: A comparative study of individual rod-shaped cells in the Mother Machine and SChemostat platforms.

Microfluidic platforms enable long-term quantification of stochastic behaviors of individual bacterial cells under precisely controlled growth conditions. Yet, quantitative comparisons of physiological parameters and cell behaviors of different microorganisms in different experimental and device modalities is not available due to experiment-specific details affecting cell physiology. To rigorously assess the effects of mechanical confinement, we designed, engineered, and performed side-by-side experiments under otherwise identical conditions in the Mother Machine (with confinement) and the SChemostat (without confinement), using the latter as the ideal comparator. We established a protocol to cultivate a suitably engineered rod-shaped mutant of Caulobacter crescentus in the Mother Machine and benchmarked the differences in stochastic growth and division dynamics with respect to the SChemostat. While the single-cell growth rate distributions are remarkably similar, the mechanically confined cells in the Mother Machine experience a substantial increase in interdivision times. However, we find that the division ratio distribution precisely compensates for this increase, which in turn reflects identical emergent simplicities governing stochastic intergenerational homeostasis of cell sizes across device and experimental configurations, provided the cell sizes are appropriately mean-rescaled in each condition. Our results provide insights into the nature of the robustness of the bacterial growth and division machinery.

An immune-competent human gut microphysiological system enables inflammation-modulation by Faecalibacterium prausnitzii.

Crosstalk of microbes with human gut epithelia and immune cells is crucial for gut health. However, there is no existing system for a long-term co-culture of human innate immune cells with epithelium and oxygen-intolerant commensal microbes, hindering the understanding of microbe-immune interactions in a controlled manner. Here, we established a gut epithelium-microbe-immune (GuMI) microphysiological system to maintain the long-term continuous co-culture of Faecalibacterium prausnitzii/Faecalibacterium duncaniae with colonic epithelium, antigen-presenting cells (APCs, herein dendritic cells and macrophages), and CD4+ naive T cells circulating underneath the colonic epithelium. In GuMI-APC condition, multiplex cytokine assays suggested that APCs contribute to the elevated level of cytokines and chemokines secreted into both apical and basolateral compartments compared to GuMI condition that lacks APC. In GuMI-APC with F. prausnitzii (GuMI-APC-FP), F. prausnitzii increased the transcription of pro-inflammatory genes such as toll-like receptor 1 (TLR1) and interferon alpha 1 (IFNA1) in the colonic epithelium, without a significant effect on cytokine secretion, compared to the GuMI-APC without bacteria (GuMI-APC-NB). In contrast, in the presence of CD4+ naive T cells (GuMI-APCT-FP), TLR1, IFNA1, and IDO1 transcription levels decreased with a simultaneous increase in F. prausnitzii-induced secretion of pro-inflammatory cytokines (e.g., IL8) compared to GuMI-APC-FP that lacks T cells. These results highlight the contribution of individual innate immune cells in regulating the immune response triggered by the gut commensal F. prausnitzii. The integration of defined populations of immune cells in the gut microphysiological system demonstrated the usefulness of GuMI physiomimetic platform to study microbe-epithelial-immune interactions in healthy and disease conditions.

Emergent Spatiotemporal Organization in Stochastic Intracellular Transport Dynamics.

The interior of a living cell is an active, fluctuating, and crowded environment, yet it maintains a high level of coherent organization. This dichotomy is readily apparent in the intracellular transport system of the cell. Membrane-bound compartments called endosomes play a key role in carrying cargo, in conjunction with myriad components including cargo adaptor proteins, membrane sculptors, motor proteins, and the cytoskeleton. These components coordinate to effectively navigate the crowded cell interior and transport cargo to specific intracellular locations, even though the underlying protein interactions and enzymatic reactions exhibit stochastic behavior. A major challenge is to measure, analyze, and understand how, despite the inherent stochasticity of the constituent processes, the collective outcomes show an emergent spatiotemporal order that is precise and robust. This review focuses on this intriguing dichotomy, providing insights into the known mechanisms of noise suppression and noise utilization in intracellular transport processes, and also identifies opportunities for future inquiry. Expected final online publication date for the Annual Review of Biophysics, Volume 53 is May 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Complete genome sequences of Methylococcus capsulatus (Norfolk) and Methylocaldum szegediense (Norfolk) isolated from a landfill methane biofilter.

Here we report the complete genome sequence of two moderately thermophilic methanotrophs isolated from a landfill methane biofilter, Methylococcus capsulatus (Norfolk) and Methylocaldum szegediense (Norfolk).

An immune-competent human gut microphysiological system enables inflammation-modulation of Faecalibacterium prausnitzii.

Crosstalk of microbes with human gut epithelia and immune cells is crucial for gut health. However, there is no existing system for a long-term co-culture of human innate immune cells with epithelium and oxygen-intolerant commensal microbes, hindering the understanding of microbe-immune interactions in a controlled manner. Here, we establish a gut epithelium-microbe-immune microphysiological system to maintain the long-term continuous co-culture of Faecalibacterium prausnitzii/Faecalibacterium duncaniae with colonic epithelium, antigen-presenting cells (APCs, herein dendritic cells and macrophages), with CD4+ naïve T cells circulating underneath the colonic epithelium. Multiplex cytokine assays suggested that APCs contribute to the elevated level of cytokines and chemokines being secreted into both apical and basolateral compartments. In contrast, the absence of APCs does not allow reliable detection of these cytokines. In the presence of APCs, F. prausnitzii increased the transcription of pro-inflammatory genes such as toll-like receptor 1 (TLR1) and interferon alpha 1 (IFNA1) in the colonic epithelium, but no significant change on the secreted cytokines. In contrast, integration of CD4+ naïve T cells reverses this effect by decreasing the transcription of TLR1, IFNA1, and indoleamine 2,3-dioxygenase, and increasing the F. prausnitzii-induced secretion of pro-inflammatory cytokines such as IL-8, MCP-1/CCL2, and IL1A. These results highlight the contribution of individual innate immune cells in the regulation of the immune response triggered by the gut commensal F. prausnitzii. The successful integration of defined populations of immune cells in this gut microphysiological system demonstrated the usefulness of the GuMI physiomimetic platform to study microbe-epithelial-immune interactions in health and disease.

Establishment of a 96-well transwell system using primary human gut organoids to capture multiple quantitative pathway readouts.

Disruptions in the gut epithelial barrier can lead to the development of chronic indications such as inflammatory bowel disease (IBD). Historically, barrier function has been assessed in cancer cell lines, which do not contain all human intestinal cell types, leading to poor translatability. To bridge this gap, we adapted human primary gut organoids grown as monolayers to quantify transcription factor phosphorylation, gene expression, cytokine production, and barrier function. In this work we describe and characterize a novel 96-well human gut organoid-derived monolayer system that enables quantitative assessment of candidate therapeutics. Normal human intestine differentiation patterns and barrier function were characterized and confirmed to recapitulate key aspects of in vivo biology. Next, cellular response to TNF-α (a central driver of IBD) was determined using a diverse cadre of quantitative readouts. We showed that TNF-α pathway antagonists rescued damage caused by TNF-α in a dose-dependent manner, indicating that this system is suitable for quantitative assessment of barrier modulating factors. Taken together, we have established a robust primary cell-based 96-well system capable of interrogating questions around mucosal response. This system is well suited to provide pivotal functional data to support translational target and drug discovery efforts.

A review of implementation intentions as a tool to benefit high-need patients and healthcare systems: U.S. veterans affairs as an exemplar.

Implementation intentions (if-then plans) are an evidence-based behavior change strategy designed to translate behavioral intentions into habits [1]. Despite extensive evidence of its potential utility, this behavior change strategy is underutilized and under-researched in high-need healthcare contexts within the United States (U.S.) which face high rates of chronic conditions and barriers to care such as rurality, lack of resources, and cognitive strain from mental health and neurological conditions [2,3]. Implementation intentions have demonstrated efficacy in promoting many health behaviors proven to mitigate chronic conditions, namely physical activity, healthy diet, and substance use reduction [4-6]. In addition, the accessible, adaptable, and self-driven nature of implementation intentions allow the technique to meet many of the individual and system-level priorities of these high-need care contexts. By being patient-driven, proactive, and personalized, implementation intentions can help these patients cultivate healthy habits as part of their everyday lives. At the systems-level, implementation intentions' inexpensiveness, scalability, and compatibility with telemedicine platforms allow them to be integrated easily into existing healthcare system infrastructure [7,8]. This review describes these concepts in detail, and uses the Veterans Affairs (VA) healthcare system as an exemplar to provide concrete examples of how and where implementation intentions could be integrated in a healthcare system, within some existing programs, to benefit both the system and individual patients.

Deterministic early endosomal maturations emerge from a stochastic trigger-and-convert mechanism.

Endosomal maturation is critical for robust and timely cargo transport to specific cellular compartments. The most prominent model of early endosomal maturation involves a phosphoinositide-driven gain or loss of specific proteins on individual endosomes, emphasising an autonomous and stochastic description. However, limitations in fast, volumetric imaging long hindered direct whole cell-level measurements of absolute numbers of maturation events. Here, we use lattice light-sheet imaging and bespoke automated analysis to track individual very early (APPL1-positive) and early (EEA1-positive) endosomes over the entire population, demonstrating that direct inter-endosomal contact drives maturation between these populations. Using fluorescence lifetime, we show that this endosomal interaction is underpinned by asymmetric binding of EEA1 to very early and early endosomes through its N- and C-termini, respectively. In combination with agent-based simulation which supports a 'trigger-and-convert' model, our findings indicate that APPL1- to EEA1-positive maturation is driven not by autonomous events but by heterotypic EEA1-mediated interactions, providing a mechanism for temporal and population-level control of maturation.

Which Intervention Strategies Promote the Adoption and Maintenance of Physical Activity? Evidence From Behavioral Trials With Cancer Survivors.

BACKGROUND/PURPOSE: We address four questions about interventions to promote physical activity in cancer survivors: (a) How often is both the adoption and maintenance of behavior change tested in trials? (b) How often do interventions generate adoption-plus-maintenance of behavior change? (c) Are intervention strategies specifically geared at promoting maintenance of behavior change deployed in trials? and (d) Which intervention strategies distinguish trials that promote both the adoption and maintenance of physical activity from trials that promote adoption-only or generate no behavioral changes? METHODS: Computerized literature searches identified 206 reports of randomized trials that measured physical activity in the wake of the intervention. RESULTS: Only 51 reports (24%) measured both behavioral adoption (postintervention) and behavioral maintenance (≥3 months follow-up). The 51 reports included 58 tests of interventions; 22% of tests observed both adoption and maintenance of physical activity, 26% reported adoption-only, and 52% found no change in behavior. Change techniques designed to promote behavioral maintenance were used much less frequently than adoption techniques or adoption and maintenance techniques. Interventions that aimed to improve quality of life, used supervised exercise sessions, were undertaken in community centers, and deployed fewer behavior change techniques were associated with adoption-plus-maintenance of physical activity in cancer survivors. CONCLUSIONS: The present findings offer new insights into the adoption and maintenance of physical activity and highlight the need to routinely assess these forms of behavior change in future trials. More extensive testing of intervention strategies specifically geared at maintenance of behavior change is warranted.

Cancer survivors need to not only adopt, but also maintain, physical activity to benefit their health and wellbeing. We undertook a systematic review of interventions to promote the adoption and maintenance of physical activity in cancer survivors. Out of 206 physical activity interventions for cancer survivors that we identified, only 51 (24%) measured both the adoption and maintenance of behavior change. Of these 51 intervention studies, only 22% were effective in promoting both the adoption and maintenance of physical activity. We developed a new classification of behavior change techniques used in interventions and discovered that techniques specifically designed to promote behavioral maintenance were used only rarely. We found that interventions that aimed to improve quality of life, used supervised exercise sessions, and were undertaken in community centers predicted adoption-plus-maintenance of physical activity in cancer survivors. These findings underscore the need for more trials that assess the adoption and maintenance of physical activity and for new research programs focused on evaluating the efficacy of maintenance techniques.

Cellular learning: Habituation sans neurons in a unicellular organism.

Stentor coeruleus cells stochastically switch between non-responsive (contracted) and responsive (extended) states. Learning is accomplished via habituation, in which the internal model is updated to reflect the current environment by tuning the transition rates according to the time series properties of mechanical stimuli.

How Does Self-Control Promote Health Behaviors? A Multi-Behavior Test of Five Potential Pathways.

BACKGROUND: Self-control is generally defined as the capacity to override impulses and is a robust predictor of health behaviors. This paper integrates trait, reasoned action, and habit approaches to develop and test a mechanistic account of how self-control influences health actions. PURPOSE: We tested five potential pathways from self-control to behavior, termed the valuation, prioritization, habituation, translation, and inhibition routes. METHODS: At baseline, participants (N = 663 adults) completed survey measures of reasoned action approach variables and habits in relation to eight health behaviors and the Brief Self-Control Scale. Three months later, participants reported their behavior. Multi-level modeling was used to test pathways across behaviors. RESULTS: Supporting the valuation route, affective attitude, cognitive attitude, descriptive norms, and perceived behavioral control mediated the self-control-intention relation, and intentions and perceived behavioral control mediated the relationship between self-control and health behaviors. Self-control also predicted the priority accorded to different considerations during intention formation. Higher self-control was associated with stronger prediction by cognitive attitudes and perceived behavioral control and weaker prediction by habits and injunctive norms. Self-control predicted habit formation, and habits mediated the self-control-behavior relation. Finally, self-control was associated with the improved translation of intentions into health behaviors and with greater inhibition of affective and habitual influences. Findings for the different pathways were not moderated by whether approach (health-protective behaviors) or avoidance responses (health-risk behaviors) were at issue. CONCLUSIONS: The present research offers new insights into why self-control promotes health behavior performance, and how deficits in self-control might be offset in future behavior-change interventions.

Self-control is the capacity to override impulses and is known to predict engagement in health behaviors. This article tests five hypotheses about how self-control drives health actions. We find that high self-control not only helps to override impulses (feelings and habits), it also influences (a) how favorable are people's thoughts, feelings, and intentions about health behaviors, (b) what considerations determine the intention to act (e.g., high self-control means people give higher priority to the perceived healthiness of the behavior and how much control they have over its performance), (c) whether people form habits that make it less effortful to perform health behaviors, and (d) how effectively people translate their "good" intentions into health behaviors. Thus, we find support for five different routes from self-control to engagement in health behaviors.

Health and environmental impact assessment of landfill mining activities: A case study in Norfolk, UK.

The release of fine particles during mechanical landfill mining (LFM) operations is a potential environmental pollution and human health risk. Previous studies demonstrate that a significant proportion (40-80% wt) of the content of fine soil-like materials within the size range <10 mm to <4 mm recovered from such operations originate from municipal solid waste (MSW) landfills. This study evaluates the potential health risks caused by emissions from LFM activities. MSW samples recovered from the drilling of four different wells of a closed UK landfill were analysed for physical, chemical, and biological properties to determine the extent of potential contaminant emissions during LFM activities. The results show that fine particles (approximately ≤1.5 mm) accounted for more than 50% of the total mass of excavated waste and contained predominantly soil-like materials. The concentrations of Zn, Cu, Pb, Cd, As, and Cr exceed the permissible limits set by the current UK Soil Guideline Values. The highest geoaccumulation index and contamination factor values for Cu were 2.51 and 12.51, respectively, indicating a moderate to very high degree of contamination. Unsurprisingly, the pollution load index was >1, indicating the extent of pollution within the study area. The hazard quotient values indicated high exposure-related risks for Pb (16.95), Zn (3.56), Cd (1.47), and As (1.46) for allotment land use and As (1.96) for residential land use. The cancer-related risk values were higher than the acceptable range of 1.0 × 10-6 to 1.0 × 10-4. The cancer risk factor indicated that Cr and As were the major human health risk hazards.

Reduction in Hospital Transfers at a US COVID-19 Alternate Care Site: Maintaining Surge Capacity Support in Imperial County, California.

OBJECTIVE: The transfer rate for patients from an Alternate Care Site (ACS) back to a hospital may serve as a metric of appropriate patient selection and the ability of an ACS to treat moderate to severely ill patients accepted from overwhelmed health-care systems. During the coronavirus infectious disease 2019 (COVID-19) pandemic, hospitals worldwide experienced acute surges of patients presenting with acute respiratory failure. METHODS: An ACS in Imperial County, California was re-established in November 2020 to help decompress 2 local hospitals experiencing surges of COVID-19 cases. The patients treated often had multiple comorbid illnesses and required a median supplemental oxygen of 3 L/min (LPM) on admission. Numerous interventions were initiated during a 2-wk period to improve clinical care delivery. RESULTS: The objectives of this retrospective observational study are to evaluate the impact of these clinical and staff interventions at an ACS on the transfer rate and to provide issues to consider for future ACS sites managing COVID-19 patients. CONCLUSIONS: The data suggest that continuous, real-time process-improvement interventions helped reduce the transfer rate back to hospitals from 36.7% to 14.5% and that an ACS is a viable option for managing symptomatic COVID-19 positive patients requiring hospital-level care when hospitals are overburdened.

Color scrambles reveal red and green half-wave linear mechanisms plus a mechanism selective for low chromatic contrast.

This paper introduces a new method to determine how subjects make discriminations among red-green texture stimuli. More specifically, the method determines (1) the number of mechanisms in human vision sensitive to lights that vary along the constant-S cardinal axis (cSCA) of DKL space and (2) the sensitivity of each mechanism to cSCA lights. Each of five subjects was tested in four, separately-blocked tasks. In each task, the subject strove to detect the location of a patch of cSCA-scramble (a spatially random mixture of cSCA lights) in a large, annular background of cSCA-scramble with a different histogram. In different tasks the target patch was (1) redder, (2) greener, (3) higher in red-green contrast, and (4) lower in red-green contrast than the background. For each subject in each task, we measure how target salience is influenced by different cSCA lights. By assuming that in each task each subject uses a weighted sum of his-or-her available mechanisms to construct a "tool" that is optimal for detecting the target, we can derive the sensitivity functions of the mechanisms underlying performance. Results suggest that human vision possesses three mechanisms sensitive to cSCA lights: a red half-wave linear mechanism, a complementary green half-wave linear mechanism, and a third mechanism that is activated by color-scrambles with low chromatic contrast in high-chromatic-contrast backgrounds.

Does increasing autonomous motivation or perceived competence lead to health behavior change? A meta-analysis.

OBJECTIVE: Despite abundant observational and experimental tests, it is not yet clear whether enhancing autonomous motivation or perceived competence leads to health behavior change. We identified interventions that aimed to change these constructs and quantified the magnitude of changes in behavior observed when interventions generated increases in autonomous motivation, perceived competence, or both. METHOD: Computerized searches and additional strategies identified 67 articles that yielded 135 effect sizes relevant to our research questions. Random effects meta-analyses were conducted via STATA. RESULTS: Interventions increased autonomous motivation and perceived competence in 31% and 38% of tests, respectively. Increasing autonomous motivation led to a medium change in health behaviors (d+ = .47, 95% CI [.44, .83]) and increasing perceived competence generated a small-to-medium change (d+ = .34, 95% CI [.22, .47]). Interventions that failed to generate significant improvements in autonomous motivation and perceived competence had much smaller effects on behavior change (d+ = .13 and .10, respectively). There was little evidence of synergistic effects. Changing both autonomous motivation and perceived competence (d+ = .42) did not lead to a larger effect on behavior compared with changing autonomous motivation on its own (d+ = .61), but had a larger effect compared with changing perceived competence on its own (d+ = .21). CONCLUSION: The present review suggests that autonomous motivation and perceived competence are valid targets for interventions to promote health behavior change but also indicates that research is warranted to ensure that interventions more effectively engage these targets. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Benchmarking the effectiveness of interventions to promote physical activity: A metasynthesis.

OBJECTIVE: The effectiveness of physical activity interventions is typically evaluated using null hypothesis significance testing or conventional interpretations of effect size (i.e., "small," "medium," or "large"). As these criteria have recently attracted criticism, we conducted a quantitative integration of meta-analyses (a metasynthesis) in order to provide precise, numerical estimates of intervention effectiveness. The research aimed to specify the percentile distribution of effect sizes in meta-analyses of physical activity trials, and their corresponding values for different types of activity (i.e., steps per day, minutes of moderate/vigorous physical activity [MVPA], meeting World Health Organization (WHO) physical activity guidelines). METHOD: Computerized searches identified 104 meta-analyses incorporating findings from 2,762 trials that met the inclusion criteria for the metasynthesis. RESULTS: The median effect size across all meta-analyses was d+ = .21, equivalent to an increase of 1,320 steps per day, 15.6 additional minutes of daily MVPA, and a 4.3% increase in the proportion of participants meeting WHO guidelines. Separate percentile distributions were computed for different samples (e.g., children, older adults, cancer survivors), measures of physical activity (i.e., objective vs. self-report), settings (e.g., schools, workplace), and follow-up periods (3+, 6+, and 12+ months). CONCLUSIONS: Conventional interpretations of effect size gravely misrepresent the effectiveness of interventions to promote physical activity. The percentile values for effect sizes, steps per days, minutes of MVPA, and percentage meeting guidelines reported here can be used to benchmark the effectiveness of future trials and should enable more informed judgments about trade-offs between effectiveness and considerations such as reach, burden, and cost. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Medical Care at California Wildfire Incident Base Camps.

OBJECTIVE: The California Emergency Medical Services Authority manages and deploys California Medical Assistance Teams (CAL-MAT) to disaster medical incidents in the state. This analysis reviews diagnoses for ambulatory medical visits at multiple wildland fire incident base camp field sites in California during the 2020 fire season. METHODS: Clinical data without personal health information were extracted retrospectively from patient care records from all patients seen by a provider. Results were entered into Excel spreadsheets with calculation of summary statistics. RESULTS: During the 2020 fire season, CAL-MAT teams deployed 21 times for a total of 327 days to base camps supporting large fire incidents and cared for 1756 patients. Impacts of heat and environmental smoke are a constant factor near wildfires; however, our most common medical problem was rhus dermatitis (54.5%) due to poison oak. All 2020 medical missions were further complicated by prevention and management of coronavirus disease (COVID-19). CONCLUSIONS: There is very little literature regarding the acute medical needs facing responders fighting wildland fires. Ninety-five percent of clinical conditions presenting to a field medical team at the wildfire incident base camp during a severe fire season in California can be managed by small teams operating in field tents.

Assessing donor-to-donor variability in human intestinal organoid cultures.

Donor-to-donor variability in primary human organoid cultures has not been well characterized. As these cultures contain multiple cell types, there is greater concern that variability could lead to increased noise. In this work we investigated donor-to-donor variability in human gut adult stem cell (ASC) organoids. We examined intestinal developmental pathways during culture differentiation in ileum- and colon-derived cultures established from multiple donors, showing that differentiation patterns were consistent among cultures. This finding indicates that donor-to-donor variability in this system remains at a manageable level. Intestinal metabolic activity was evaluated by targeted analysis of central carbon metabolites and by analyzing hormone production patterns. Both experiments demonstrated similar metabolic functions among donors. Importantly, this activity reflected intestinal biology, indicating that these ASC organoid cultures are appropriate for studying metabolic processes. This work establishes a framework for generating high-confidence data using human primary cultures through thorough characterization of variability.

Coculture of primary human colon monolayer with human gut bacteria.

The presence of microbes in the colon impacts host physiology. Therefore, microbes are being evaluated as potential treatments for colorectal diseases. Humanized model systems that enable robust culture of primary human intestinal cells with bacteria facilitate evaluation of potential treatments. Here, we describe a protocol that can be used to coculture a primary human colon monolayer with aerotolerant bacteria. Primary human colon cells maintained as organoids are dispersed into single-cell suspensions and then seeded on collagen-coated Transwell inserts, where they attach and proliferate to form confluent monolayers within days of seeding. The confluent monolayers are differentiated for an additional 4 d and then cocultured with bacteria. As an example application, we describe how to coculture differentiated colon cells for 8 h with four strains of Bacteroides thetaiotaomicron, each engineered to detect different colonic microenvironments via genetically embedded logic circuits incorporating deoxycholic acid and anhydrotetracycline sensors. Characterization of this coculture system reveals that barrier function remains intact in the presence of engineered B. thetaiotaomicron. The bacteria stay close to the mucus layer and respond in a microenvironment-specific manner to the inducers (deoxycholic acid and anhydrotetracycline) of the genetic circuits. This protocol thus provides a useful mucosal barrier system to assess the effects of bacterial cells that respond to the colonic microenvironment, and may also be useful in other contexts to model human intestinal barrier properties and microbiota-host interactions.

Primary human colonic mucosal barrier crosstalk with super oxygen-sensitive Faecalibacterium prausnitzii in continuous culture.

BACKGROUND: The gut microbiome plays an important role in human health and disease. Gnotobiotic animal and in vitro cell-based models provide some informative insights into mechanistic crosstalk. However, there is no existing system for a long-term co-culture of a human colonic mucosal barrier with super oxygen-sensitive commensal microbes, hindering the study of human-microbe interactions in a controlled manner. METHODS: Here, we investigated the effects of an abundant super oxygen-sensitive commensal anaerobe, Faecalibacterium prausnitzii, on a primary human mucosal barrier using a Gut-MIcrobiome (GuMI) physiome platform that we designed and fabricated. FINDINGS: Long-term continuous co-culture of F. prausnitzii for two days with colon epithelia, enabled by continuous flow of completely anoxic apical media and aerobic basal media, resulted in a strictly anaerobic apical environment fostering growth of and butyrate production by F. prausnitzii, while maintaining a stable colon epithelial barrier. We identified elevated differentiation and hypoxia-responsive genes and pathways in the platform compared with conventional aerobic static culture of the colon epithelia, attributable to a combination of anaerobic environment and continuous medium replenishment. Furthermore, we demonstrated anti-inflammatory effects of F. prausnitzii through HDAC and the TLR-NFKB axis. Finally, we identified that butyrate largely contributes to the anti-inflammatory effects by downregulating TLR3 and TLR4. CONCLUSIONS: Our results are consistent with some clinical observations regarding F. prausnitzii, thus motivating further studies employing this platform with more complex engineered colon tissues for understanding the interaction between the human colonic mucosal barrier and microbiota, pathogens, or engineered bacteria.