An engineered bacterial symbiont allows noninvasive biosensing of the honey bee gut environment.

The honey bee is a powerful model system to probe host-gut microbiota interactions, and an important pollinator species for natural ecosystems and for agriculture. While bacterial biosensors can provide critical insight into the complex interplay occurring between a host and its associated microbiota, the lack of methods to noninvasively sample the gut content, and the limited genetic tools to engineer symbionts, have so far hindered their development in honey bees. Here, we built a versatile molecular tool kit to genetically modify symbionts and reported for the first time in the honey bee a technique to sample their feces. We reprogrammed the native bee gut bacterium Snodgrassella alvi as a biosensor for IPTG, with engineered cells that stably colonize the gut of honey bees and report exposure to the molecules in a dose-dependent manner through the expression of a fluorescent protein. We showed that fluorescence readout can be measured in the gut tissues or noninvasively in the feces. These tools and techniques will enable rapid building of engineered bacteria to answer fundamental questions in host-gut microbiota research.

Mechanical and cold polymodality coexist in tactile peripheral afferents, and it's not mediated by TRPM8.

In the mammalian somatosensory system, polymodality is defined as the competence of some neurons to respond to multiple forms of energy (e.g., mechanical and thermal). This ability is thought to be an exclusive property of nociceptive neurons (polymodal C-fiber nociceptors) and one of the pillars of nociceptive peripheral plasticity. The current study uncovered a completely different neuronal sub-population with polymodal capabilities on the opposite mechanical modality spectrum (tactile). We have observed that several tactile afferents (1/5) can respond to cold in non-nociceptive ranges. These cells' mechanical thresholds and electrical properties are similar to any low-threshold mechano-receptors (LT), conducting in a broad range of velocities (Aδ to Aß), lacking CGRP and TRPM8 receptors. Due to its density, cold-response range, speed, and response to injury (or lack thereof), we speculate on its role in controlling reflexive behaviors (wound liking and rubbing) and modulation of nociceptive spinal cord integration. Further studies are required to understand the mechanisms behind this neuron's polymodality, central architecture, and impact on pain perception.

Effects of systemic oxytocin administration on ultraviolet B-induced nociceptive hypersensitivity and tactile hyposensitivity in mice.

Ultraviolet B (UVB) radiation induces cutaneous inflammation, leading to thermal and mechanical hypersensitivity. Here, we examine the mechanical properties and profile of tactile and nociceptive peripheral afferents functionally disrupted by this injury and the role of oxytocin (OXT) as a modulator of this disruption. We recorded intracellularly from L4 afferents innervating the irradiated area (5.1 J/cm2) in 4-6 old week male mice (C57BL/6J) after administering OXT intraperitoneally, 6 mg/Kg. The distribution of recorded neurons was shifted by UVB radiation to a pattern observed after acute and chronic injuries and reduced mechanical thresholds of A and C- high threshold mechanoreceptors while reducing tactile sensitivity. UVB radiation did not change somatic membrane electrical properties or fiber conduction velocity. OXT systemic administration rapidly reversed these peripheral changes toward normal in both low and high-threshold mechanoreceptors and shifted recorded neuron distribution toward normal. OXT and V1aR receptors were present on the terminals of myelinated and unmyelinated afferents innervating the skin. We conclude that UVB radiation, similar to local tissue surgical injury, cancer metastasis, and peripheral nerve injury, alters the distribution of low and high threshold mechanoreceptors afferents and sensitizes nociceptors while desensitizing tactile units. Acute systemic OXT administration partially returns all of those effects to normal.

Neuroactive metabolites modulated by the gut microbiota in honey bees.

Honey bees have emerged as a new model to study the gut-brain axis, as they exhibit complex social behaviors and cognitive abilities, while experiments with gnotobiotic bees have revealed that their gut microbiota alters both brain and behavioral phenotypes. Furthermore, while honey bee brain functions supporting a broad range of behaviors have been intensively studied for over 50 years, the gut microbiota of bees has been experimentally characterized only recently. Here, we combined six published datasets from metabolomic analyses to provide an overview of the neuroactive metabolites whose abundance in the gut, hemolymph and brain varies in presence of the gut microbiota. Such metabolites may either be produced by gut bacteria, released from the pollen grains during their decomposition by bacteria, or produced by other organs in response to different bacterial products. We describe the current state of knowledge regarding the impact of such metabolites on brain function and behavior and provide further hypotheses to explore in this emerging field of research.

A new fluorescent probe for the visualization of progerin.

Hutchinson-Gilford progeria syndrome (HGPS) or progeria is a rare genetic disease that causes premature aging, leading to a drastic reduction in the life expectancy of patients. Progeria is mainly caused by the intracellular accumulation of a defective protein called progerin, generated from a mutation in the LMNA gene. Currently, there is only one approved drug for the treatment of progeria, which has limited efficacy. It is believed that progerin levels are the most important biomarker related to the severity of the disease. However, there is a lack of effective tools to directly visualize progerin in the native cellular models, since the commercially available antibodies are not well suited for the direct visualization of progerin in cells from the mouse model of the disease. In this context, an alternative option for the visualization of a protein relies on the use of fluorescent chemical probes, molecules with affinity and specificity towards a protein. In this work we report the synthesis and characterization of a new fluorescent probe (UCM-23079) that allows for the direct visualization of progerin in cells from the most widely used progeroid mouse model. Thus, UCM-23079 is a new tool compound that could help prioritize potential preclinical therapies towards the final goal of finding a definitive cure for progeria.

Lactated Ringers Use in the First 24 Hours of Hospitalization Is Associated With Improved Outcomes in 999 Patients With Acute Pancreatitis.

INTRODUCTION: Recent pilot trials in acute pancreatitis (AP) found that lactated ringers (LR) usage may result in decreased risk of moderately severe/severe AP compared with normal saline, but their small sample sizes limit statistical power. We investigated whether LR usage is associated with improved outcomes in AP in an international multicenter prospective study. METHODS: Patients directly admitted with the diagnosis of AP were prospectively enrolled at 22 international sites between 2015 and 2018. Demographics, fluid administration, and AP severity data were collected in a standardized prospective manner to examine the association between LR and AP severity outcomes. Mixed-effects logistic regression analysis was performed to determine the direction and magnitude of the relationship between the type of fluid administered during the first 24 hours and the development of moderately severe/severe AP. RESULTS: Data from 999 patients were analyzed (mean age 51 years, female 52%, moderately severe/severe AP 24%). Usage of LR during the first 24 hours was associated with reduced odds of moderately severe/severe AP (adjusted odds ratio 0.52; P = 0.014) compared with normal saline after adjusting for region of enrollment, etiology, body mass index, and fluid volume and accounting for the variation across centers. Similar results were observed in sensitivity analyses eliminating the effects of admission organ failure, etiology, and excessive total fluid volume. DISCUSSION: LR administration in the first 24 hours of hospitalization was associated with improved AP severity. A large-scale randomized clinical trial is needed to confirm these findings.

The noncoding small RNA SsrA is released by Vibrio fischeri and modulates critical host responses.

The regulatory noncoding small RNAs (sRNAs) of bacteria are key elements influencing gene expression; however, there has been little evidence that beneficial bacteria use these molecules to communicate with their animal hosts. We report here that the bacterial sRNA SsrA plays an essential role in the light-organ symbiosis between Vibrio fischeri and the squid Euprymna scolopes. The symbionts load SsrA into outer membrane vesicles, which are transported specifically into the epithelial cells surrounding the symbiont population in the light organ. Although an SsrA-deletion mutant (ΔssrA) colonized the host to a normal level after 24 h, it produced only 2/10 the luminescence per bacterium, and its persistence began to decline by 48 h. The host's response to colonization by the ΔssrA strain was also abnormal: the epithelial cells underwent premature swelling, and host robustness was reduced. Most notably, when colonized by the ΔssrA strain, the light organ differentially up-regulated 10 genes, including several encoding heightened immune-function or antimicrobial activities. This study reveals the potential for a bacterial symbiont's sRNAs not only to control its own activities but also to trigger critical responses promoting homeostasis in its host. In the absence of this communication, there are dramatic fitness consequences for both partners.

The mechanism of an electrostatic nanofilter: overcoming entropy with electrostatics.

General porins are nature's sieving machinery in the outer membrane of Gram-negative bacteria. Their unique hourglass-shaped architecture is highly conserved among different bacterial membrane proteins and other biological channels. These biological nanopores have been designed to protect the interior of the bacterial cell from leakage of toxic compounds while selectively allowing the entry of the molecules needed for cell growth and function. The mechanism of transport through porins is of utmost and direct interest for drug discovery, extending toward nanotechnology applications for blue energy, separations, and sequencing. Here we present a theoretical framework for analysing the filter of general porins in relation to translocating molecules with the aid of enhanced molecular simulations quantitatively. Using different electrostatic probes in the form of a series of related molecules, we describe the nature of this filter and how to finely tune permeability by exploiting electrostatic interactions between the pore and the translocating molecule. Eventually, we show how enhanced simulations constitute today a valid tool for characterising the mechanism and quantifying energetically the transport of molecules through nanopores.

How the physical properties of bacterial porins match environmental conditions.

Transmembrane ß-barrel proteins are key systems for transport phenomena in biology. Based on their broad substrate specificity, they represent good candidates for present and future technological applications, such as DNA/RNA and protein sequencing, sensing of biomedical analytes, and production of blue energy. For a better understanding of the process at the molecular level, we applied parallel tempering simulations in the WTE ensemble to compare two ß-barrel porins from Escherichia coli, OmpF and OmpC. Our analysis showed a different behavior of the two highly homologous porins, where subtle amino acid substitutions can modulate critical properties of mass transport. Interestingly, the differences can be mapped to the respective environmental conditions under which the two porins are expressed. Apart from reporting on the advantages of the enhanced sampling methods in assessing the molecular properties of nanopores, our comparative analysis provided new and key results to better understand biological function and technical applications. Eventually, we showed how results from molecular simulations align well with experimental single-channel measurements, thus demonstrating the mature evolution of numerical methodologies for predicting properties in this field crucial for future biomedical applications.

Potent Anti-amoebic Effects of Ibogaine, Voacangine and the Root Bark Alkaloid Fraction of Tabernaemontana arborea.

Plants of Tabernaemontana species have several pharmacological activities including antimicrobial effects. Amoebiasis continues to be a public health problem, with increasing evidence of resistance to metronidazole. In this study, we assessed the effect of the alkaloid fraction of T. arborea root bark and the alkaloids ibogaine and voacangine on the viability and infectivity of Entamoeba histolytica trophozoites. Cultures were exposed to 0.1 - 10 µg/mL for 24, 48 and 72 h, and viability was then determined using a tetrazolium dye reduction assay and type of cellular death analyzed by flow cytometry. Results showed that the alkaloid fraction, but mainly ibogaine and voacangine alkaloids, exhibited potent dose-dependent anti-amoebic activity at 24 h post-exposure (IC50 4.5 and 8.1 µM, respectively), comparable to metronidazole (IC50 6.8 µM). However, the effect decreased after 48 and 72 h of exposure to concentrations below 10 µg/mL, suggesting that the alkaloids probably were catabolized to less active derivatives by the trophozoites. The treatment of trophozoites with the IC50 s for 24 h induced significant morphological changes in the trophozoites, slight increase in granularity, and death by apoptonecrosis. The capacity of T. arborea alkaloids to inhibit the development of amoebic liver abscesses in hamsters was evaluated. Results showed that even when the treatments reduced the number of amoebic trophozoites in tissue sections of livers, they were unable to limit the formation of abscesses, suggesting their rapid processing to inactive metabolites. This work leaves open the possibility of using Tabernaemontana alkaloids as a new alternative for amoebiasis control.

A combined activation mechanism for the glucagon receptor.

We report on a combined activation mechanism for a class B G-protein-coupled receptor (GPCR), the glucagon receptor. By computing the conformational free-energy landscape associated with the activation of the receptor-agonist complex and comparing it with that obtained with the ternary complex (receptor-agonist-G protein) we show that the agonist stabilizes the receptor in a preactivated complex, which is then fully activated upon binding of the G protein. The proposed mechanism contrasts with the generally assumed GPCR activation mechanism, which proceeds through an opening of the intracellular region allosterically elicited by the binding of the agonist. The mechanism found here is consistent with electron cryo-microscopy structural data and might be general for class B GPCRs. It also helps us to understand the mode of action of the numerous allosteric antagonists of this important drug target.

The cytokine MIF controls daily rhythms of symbiont nutrition in an animal-bacterial association.

The recent recognition that many symbioses exhibit daily rhythms has encouraged research into the partner dialogue that drives these biological oscillations. Here we characterized the pivotal role of the versatile cytokine macrophage migration inhibitory factor (MIF) in regulating a metabolic rhythm in the model light-organ symbiosis between Euprymna scolopes and Vibrio fischeri As the juvenile host matures, it develops complex daily rhythms characterized by profound changes in the association, from gene expression to behavior. One such rhythm is a diurnal shift in symbiont metabolism triggered by the periodic provision of a specific nutrient by the mature host: each night the symbionts catabolize chitin released from hemocytes (phagocytic immune cells) that traffic into the light-organ crypts, where the population of V. fischeri cells resides. Nocturnal migration of these macrophage-like cells, together with identification of an E. scolopes MIF (EsMIF) in the light-organ transcriptome, led us to ask whether EsMIF might be the gatekeeper controlling the periodic movement of the hemocytes. Western blots, ELISAs, and confocal immunocytochemistry showed EsMIF was at highest abundance in the light organ. Its concentration there was lowest at night, when hemocytes entered the crypts. EsMIF inhibited migration of isolated hemocytes, whereas exported bacterial products, including peptidoglycan derivatives and secreted chitin catabolites, induced migration. These results provide evidence that the nocturnal decrease in EsMIF concentration permits the hemocytes to be drawn into the crypts, delivering chitin. This nutritional function for a cytokine offers the basis for the diurnal rhythms underlying a dynamic symbiotic conversation.

New Pharmacological Approaches for Rare Diseases.

The expression "rare disease" describes a group of diseases whose individual prevalence is low (between 3.9 and 6.6 in 10,000 subjects depending on the country) but which in total affect up to the 3-6% of the worldwide population [...].

The Modified Pancreatitis Activity Scoring System Shows Distinct Trajectories in Acute Pancreatitis: An International Study.

BACKGROUND & AIMS: The aims of this study were to: (1) assess the performance of the Pancreatitis Activity Scoring System (PASS) in a large intercontinental cohort of patients with acute pancreatitis (AP); and (2) investigate whether a modified PASS (mPASS) yields a similar predictive accuracy and produces distinct early trajectories between severity subgroups. METHODS: Data was prospectively collected through the Acute Pancreatitis Patient Registry to Examine Novel Therapies In Clinical Experience (APPRENTICE) consortium (2015-2018) involving 22 centers from 4 continents. AP severity was categorized per the revised Atlanta classification. PASS trajectories were compared between the three severity groups using the generalized estimating equations model. Four mPASS models were generated by modifying the morphine equivalent dose (MED), and their trajectories were compared. RESULTS: A total of 1393 subjects were enrolled (median age, 49 years; 51% males). The study cohort included 950 mild (68.2%), 315 (22.6%) moderately severe, and 128 (9.2%) severe AP. Mild cases had the lowest PASS at each study time point (all P < .001). A subset of patients with outlier admission PASS values was identified. In the outlier group, 70% of the PASS variation was attributed to the MED, and 66% of these patients were from the United States centers. Among the 4 modified models, the mPASS-1 (excluding MED from PASS) demonstrated high performance in predicting severe AP with an area under the receiver operating characteristic curve of 0.88 (vs area under the receiver operating characteristic of 0.83 in conventional PASS) and produced distinct trajectories with distinct slopes between severity subgroups (all P < .001). CONCLUSION: We propose a modified model by removing the MED component, which is easier to calculate, predicts accurately severe AP, and maintains significantly distinct early trajectories.

The relationship between pre-existing diabetes mellitus and the severity of acute pancreatitis: Report from a large international registry.

BACKGROUND/OBJECTIVES: The relationship between pre-existing diabetes mellitus (DM) and acute pancreatitis (AP) severity has not been established. We assessed the impact of pre-existing DM on AP severity in an international, prospectively ascertained registry. METHODS: APPRENTICE registry prospectively enrolled 1543 AP patients from 22 centers across 4 continents (8 US, 6 Europe, 5 Latin America, 3 India) between 2015 and 2018, and collected detailed clinical information. Pre-existing DM was defined a diagnosis of DM prior to AP admission. The primary outcome was AP severity defined by the Revised Atlanta Classification (RAC). Secondary outcomes were development of systemic inflammatory response syndrome (SIRS) or intensive care unit (ICU) admission. RESULTS: Pre-existing DM was present in 270 (17.5%) AP patients, of whom 252 (93.3%) had type 2 DM. Patients with pre-existing DM were significantly (p < 0.05) older (55.8 ± 16 vs. 48.3 ± 18.7 years), more likely to be overweight (BMI 29.5 ± 7 vs. 27.2 ± 6.2), have hypertriglyceridemia as the etiology (15% vs. 2%) and prior AP (33 vs. 24%). Mild, moderate, and severe AP were noted in 66%, 23%, and 11% of patients, respectively. On multivariable analysis, pre-existing DM did not significantly impact AP severity assessed by the RAC (moderate-severe vs. mild AP, OR = 0.86, 95% CI 0.63-1.18; severe vs. mild-moderate AP, OR = 1.05, 95% CI, 0.67-1.63), development of SIRS, or the need for ICU admission. No interaction was noted between DM status and continent. CONCLUSION: About one in 5 patients with AP have pre-existing DM. Once confounding risk factors are considered, pre-existing DM per se is not a risk factor for severe AP.

Antimycobacterial Activity of Alkaloids and Extracts from Tabernaemontana alba and T. arborea.

Tuberculosis is the main cause of death from a single infectious agent. Globally, according to the World Health Organization, in 2018, there were an estimated 1.2 million tuberculosis deaths. Moreover, there is a continuous appearance of drug-resistant strains. Thus, development of new antituberculosis medicines should receive high priority. Plant-derived natural products are promising candidates for this purpose. We therefore screened alkaloid extracts obtained from the root and stem barks of the Mexican Apocynaceae species Tabernaemontana alba and Tabernaemontana arborea, as well as the pure alkaloids ibogaine, voacangine, and voacamine, tested for activity against Mycobacterium tuberculosis H37Rv and cytotoxicity to mammalian Vero cells using the resazurin microtiter and the MTT assays, respectively. The extracts were analyzed by GC-MS and HPLC-UV. T. arborea root bark alkaloid extract showed the highest activity against M. tuberculosis (MIC100 = 7.8 µg/mL) of the four extracts tested. HPLC suggested that voacangine and voacamine were the major components. The latter was isolated by column chromatography, and its chemical structure was elucidated by 1H and 13C NMR, and MS. Unambiguous assignation was performed by HSQC, HMBC, and NOESY experiments. Voacamine is a dimeric bis-indole-type alkaloid and is 15 times more potent than the monomeric ibogan-type alkaloids ibogaine and voacangine (MIC100 = 15.6, 250.0, and 250.0 µg/mL, respectively). However, all of these compounds showed cytotoxicity to Vero cells, with a poor selectivity index of 1.00, 0.16, and 1.42, respectively. This is the first report of voacamine activity against M. tuberculosis.

Critical symbiont signals drive both local and systemic changes in diel and developmental host gene expression.

The colonization of an animal's tissues by its microbial partners creates networks of communication across the host's body. We used the natural binary light-organ symbiosis between the squid Euprymna scolopes and its luminous bacterial partner, Vibrio fischeri, to define the impact of colonization on transcriptomic networks in the host. A night-active predator, E. scolopes coordinates the bioluminescence of its symbiont with visual cues from the environment to camouflage against moon and starlight. Like mammals, this symbiosis has a complex developmental program and a strong day/night rhythm. We determined how symbiont colonization impacted gene expression in the light organ itself, as well as in two anatomically remote organs: the eye and gill. While the overall transcriptional signature of light organ and gill were more alike, the impact of symbiosis was most pronounced and similar in light organ and eye, both in juvenile and adult animals. Furthermore, the presence of a symbiosis drove daily rhythms of transcription within all three organs. Finally, a single mutation in V. fischeri-specifically, deletion of the lux operon, which abrogates symbiont luminescence-reduced the symbiosis-dependent transcriptome of the light organ by two-thirds. In addition, while the gills responded similarly to light-organ colonization by either the wild-type or mutant, luminescence was required for all of the colonization-associated transcriptional responses in the juvenile eye. This study defines not only the impact of symbiont colonization on the coordination of animal transcriptomes, but also provides insight into how such changes might impact the behavior and ecology of the host.

Symbiotic organs shaped by distinct modes of genome evolution in cephalopods.

Microbes have been critical drivers of evolutionary innovation in animals. To understand the processes that influence the origin of specialized symbiotic organs, we report the sequencing and analysis of the genome of Euprymna scolopes, a model cephalopod with richly characterized host-microbe interactions. We identified large-scale genomic reorganization shared between E. scolopes and Octopus bimaculoides and posit that this reorganization has contributed to the evolution of cephalopod complexity. To reveal genomic signatures of host-symbiont interactions, we focused on two specialized organs of E. scolopes: the light organ, which harbors a monoculture of Vibrio fischeri, and the accessory nidamental gland (ANG), a reproductive organ containing a bacterial consortium. Our findings suggest that the two symbiotic organs within E. scolopes originated by different evolutionary mechanisms. Transcripts expressed in these microbe-associated tissues displayed their own unique signatures in both coding sequences and the surrounding regulatory regions. Compared with other tissues, the light organ showed an abundance of genes associated with immunity and mediating light, whereas the ANG was enriched in orphan genes known only from E. scolopes Together, these analyses provide evidence for different patterns of genomic evolution of symbiotic organs within a single host.

Seeding of breast cancer cell line (MDA-MB-231LUC+) to the mandible induces overexpression of substance P and CGRP throughout the trigeminal ganglion and widespread peripheral sensory neuropathy throughout all three of its divisions.

Some types of cancer are commonly associated with intense pain even at the early stages of the disease. The mandible is particularly vulnerable to metastasis from breast cancer, and this process has been studied using a bioluminescent human breast cancer cell line (MDA-MB-231LUC+). Using this cell line and anatomic and neurophysiologic methods in the trigeminal ganglion (TG), we examined the impact of cancer seeding in the mandible on behavioral evidence of hypersensitivity and on trigeminal sensory neurons. Growth of cancer cells seeded to the mandible after arterial injection of the breast cancer cell line in Foxn1 animals (allogeneic model) induced behavioral hypersensitivity to mechanical stimulation of the whisker pad and desensitization of tactile and sensitization of nociceptive mechanically sensitive afferents. These changes were not restricted to the site of metastasis but extended to sensory afferents in all three divisions of the TG, accompanied by widespread overexpression of substance P and CGRP in neurons through the ganglion. Subcutaneous injection of supernatant from the MDA-MB-231LUC+ cell culture in normal animals mimicked some of the changes in mechanically responsive afferents observed with mandibular metastasis. We conclude that released products from these cancer cells in the mandible are critical for the development of cancer-induced pain and that the overall response of the system greatly surpasses these local effects, consistent with the widespread distribution of pain in patients. The mechanisms of neuronal plasticity likely occur in the TG itself and are not restricted to afferents exposed to the metastatic cancer microenvironment.

Inflammatory dysregulation in women with an eating disorder: Relationships with altered emotional reactivity.

BACKGROUND: Some studies suggest that inflammatory signaling dysregulation may contribute to eating disorder (ED) pathophysiology. However, little is known about the influence of inflammatory response on altered processes seen among patients with ED, such as emotional processing and reactivity. OBJECTIVES: The objectives were: (a) to investigate the systemic inflammatory response in ED women; and (b) to analyze the role of inflammatory markers in emotional reactivity. METHOD: Concentrations of several intercellular and intracellular inflammatory mediators (cytokines, prostaglandin by-products and enzymes, TBARS, and MAPK proteins) were quantified in plasma and PBMCs from 68 women with an ED (m = 22.01 years, SD = 9.15) and 35 healthy controls (m = 18.54 years, SD = 4.21). Moreover, emotional reactivity to affective pictures (those without either food or thinness content) was studied using the adult (>18 years old) sample (n = 41). RESULTS: Between-group differences were revealed for most markers (TNF-α, PGE2 , COX2, and ratio of activated MAPK proteins), pointing to increased inflammatory response in patients (p < .01). Women with ED showed heightened emotional reactivity, regardless of picture valence. Principal components derived from inflammatory markers showed an explanatory loading on patient's emotional reaction, in terms of valence and arousal. CONCLUSION: This study corroborates the altered systemic inflammatory response in patients with ED. The inflammatory dysregulation may contribute to ED phenotype, as seen by its relationship with heightened emotional reactivity, even though the inflammatory markers were not evaluated throughout the emotional reactivity protocol.