3-propionic Acid Research Articles

A gut microbial metabolite cocktail fights against obesity through modulating the gut microbiota and hepatic leptin signaling.

Excessive body weight and obesity elevate the risk of chronic non-communicable diseases. The judicious application of the gut microbiome, encompassing both microorganisms and their derived compounds, holds considerable promise in the treatment of obesity. In this study, we showed that a cocktail of gut microbiota-derived metabolites, comprising indole 3-propionic acid (IPA), sodium butyrate (SB) and valeric acid (VA), alleviated various symptoms of obesity in both male and female mice subjected to a high-fat diet (HFD). The 16S ribosomal RNA (rRNA) sequencing revealed that administering the cocktail via oral gavage retained the gut microbiota composition in obese mice. Fecal microbiota transplantation using cocktail-treated mice as donors mitigated the obesity phenotype of HFD-fed mice. Transcriptomic sequencing analysis showed that the cocktail preserved the gene expression profile of hepatic tissues in obese mice, especially up-regulated the expression level of leptin receptor. Gene delivery via in vivo fluid dynamics further validated that the anti-obesity efficacy of the cocktail was dependent on leptin signaling at least partly. The cocktail also inhibited the expression of appetite stimulators in hypothalamus. Together, the metabolite cocktail combated adiposity by retaining the gut microbiota configuration and activating the hepatic leptin signaling pathway. Our findings provide a sophisticated regulatory network between the gut microbiome and host, and highlight a cocktail of gut microbiota-derived metabolites, including IPA, SB, and VA, might be a prospective intervention for anti-obesity in a preclinical setting. © 2024 Society of Chemical Industry.

Effect of indole 3-propionic acid from microbiota on the immunity of CD8+ T cell to improve chemotherapy of colorectal cancer.

e15194 Background: Sensitivity of chemotherapy is a great challenge to improve the treatment efficacy in patients with colorectal cancer (CRC). Increasing study has revealed the role of microbiota in the modulation of chemotherapy sensitivity. However, the mechanism how microbiota regulates the efficacy of 5-fluorouracil (5-FU) is far from clear. Methods: We used germ-free mice and antibiotic-treated mice to demonstrate the impact of the gut microbiota on 5-FU sensitivity. Metabolomics analysis of serum from patients with CRC or mice experiments were applied to identify the key metabolite, indole 3-propionic acid (IPA). Specific pattern of microbiota with capability to produce IPA was revealed by metagenomics analysis of the mice feces. Single-cell RNA (scRNA) sequencing was subsequently used and antibody blockade experiments as well as T cell adoptive transfer experiment were conducted to confirm the role of CD8+ T cells in 5-FU treatment. AHR KO mice model was used to reveal how IPA regulate the immunity of CD8+ T cells. Engineering Escherichia coli strain BL21 with capability to produce IPA was constructed to modulate the chemotherapy sensitivity. Results: Decreased sensitivity of 5-FU chemotherapy was observed in both germ-free mice and antibiotic-treated mice models. Accumulation of serum IPA was found in mice with vancomycin intervention and verified in CRC patient with chemotherapy resistance. Additionally, metagenomic analysis of mice feces revealed that Clostridium sporogenes capable of producing IPA, are crucial for 5-FU chemotherapy sensitivity. Supplementation with IPA or Clostridium sporogenes could obviously improve the sensitivity of 5-FU chemotherapy. Subsequently scRNA sequencing analysis of tumor tissue revealed a higher infiltration of CD8+ T cells after IPA intervention. The role of IPA-induced CD8+ T cells in 5-FU treatment was confirmed by antibody blockade experiments and T cell adoptive transfer experiment. Further, improved therapeutic sensitivity by IPA and the infiltration of CD8+ T cells were vanished in AHR KO mice model. Biosynthesis of IPA by engineering bacteria was found to enhance the sensitivity of 5-FU chemotherapy. Conclusions: Indole 3-propionic acid from microbiota enhances the immunity of CD8+ T cell via activation of AHR signaling pathway, thus providing potential therapeutic strategies to improve the efficacy of chemotherapy in colorectal cancer.

Microbiota-indole 3-propionic acid-brain axis mediates abnormal synaptic pruning of hippocampal microglia and susceptibility to ASD in IUGR offspring

BackgroundAutism spectrum disorder (ASD) has been associated with intrauterine growth restriction (IUGR), but the underlying mechanisms are unclear.ResultsWe found that the IUGR rat model induced by prenatal caffeine exposure (PCE) showed ASD-like symptoms, accompanied by altered gut microbiota and reduced production of indole 3-propionic acid (IPA), a microbiota-specific metabolite and a ligand of aryl hydrocarbon receptor (AHR). IUGR children also had a reduced serum IPA level consistent with the animal model. We demonstrated that the dysregulated IPA/AHR/NF-κB signaling caused by disturbed gut microbiota mediated the hippocampal microglia hyperactivation and neuronal synapse over-pruning in the PCE-induced IUGR rats. Moreover, postnatal IPA supplementation restored the ASD-like symptoms and the underlying hippocampal lesions in the IUGR rats.ConclusionsThis study suggests that the microbiota-IPA-brain axis regulates ASD susceptibility in PCE-induced IUGR offspring, and supplementation of microbiota-derived IPA might be a promising interventional strategy for ASD with a fetal origin.21xhjpDoyB4JmdH7kH-NGnVideo

Redox Targets for Phosphine–Boranes

Understanding the complex mechanisms underlying redox-mediated biological processes is a fundamental pillar of cellular biology. We describe the identification and quantification of disulfide formation and reduction in response to phosphine–borane complexes. We illustrate the specific cysteine reduction effects of the novel phosphine–borane complex bis(3-propionic acid methyl ester) phenylphosphine–borane complex (PB1) on cultured 661W cells. A total of 1073 unique protein fragments from 628 unique proteins were identified and quantified, of which 13 were found to be statistically significant in comparison to control cells. Among the 13 identified proteins were Notch1, HDAC1, UBA1, USP7, and subunits L4 and L7 of the 60S ribosomal subunit, all of which are involved in redox or cell death-associated pathways. Leveraging the ability of tandem mass tagging mass spectrometry to provide quantitative data in an exploratory manner provides insight into the effect PB1 and other phosphine–borane compounds may have on the cysteine redoxome.

Maternal PBDE exposure disrupts gut microbiome and promotes hepatic proinflammatory signaling in humanized PXR-transgenic mouse offspring over time.

Developmental exposure to the persistent environmental pollutant, polybrominated diphenyl ethers (PBDEs), is associated with increased diabetes prevalence. The microbial tryptophan metabolite, indole-3-propionic acid (IPA), is associated with reduced risk of type 2 diabetes and lower-grade inflammation and is a pregnane X receptor (PXR) activator. To explore the role of IPA in modifying the PBDE developmental toxicity, we orally exposed humanized PXR-transgenic (hPXR-TG) mouse dams to vehicle, 0.1 mg/kg/day DE-71 (an industrial PBDE mixture), DE-71+IPA (20 mg/kg/day), or IPA, from 4 weeks preconception to the end of lactation. Pups were weaned at 21 days of age and IPA supplementation continued in the corresponding treatment groups. Tissues were collected at various ages until 6 months of age (n = 5 per group). In general, the effect of maternal DE-71 exposure on the gut microbiome of pups was amplified over time. The regulation of hepatic cytokines and prototypical xenobiotic-sensing transcription factor target genes by DE-71 and IPA was age- and sex-dependent, where DE-71-mediated mRNA increased selected cytokines (Il10, Il12p40, Il1β [both sexes], and [males]). The hepatic mRNA of the aryl hydrocarbon receptor (AhR) target gene Cyp1a2 was increased by maternal DE-71 and DE-71+IPA exposure at postnatal day 21 but intestinal Cyp1a1 was not altered by any of the exposures and ages. Maternal DE-71 exposure persistently increased serum indole, a known AhR ligand, in age- and sex-dependent manner. In conclusion, maternal DE-71 exposure produced a proinflammatory signature along the gut-liver axis, including gut dysbiosis, dysregulated tryptophan microbial metabolism, attenuated PXR signaling, and elevated AhR signaling in postweaned hPXR-TG pups over time, which was partially corrected by IPA supplementation.

Lead Sequestration in Perovskite Photovoltaic Device Encapsulated with Water-Proof and Adhesive Poly(ionic liquid)

The inevitable usage of toxic lead impedes the commercialization of lead halide perovskite solar cells, especially considering lead ions potentially unseals from the discarded and damaged devices and consequently contaminates the environment. In this work, we proposed a poly(ionic liquid) (PIL) cohered sandwich structure (PCSS) to realize lead sequestration in perovskite solar cells by a water-proof and adhesive poly([1-(3-propionic acid)-3-vinylimidazolium] bis(trifluoromethanesulphonyl)imide (PPVI-TFSI). A transparent ambidextrous protective shield manufactured from PPVI-TFSI was achieved and applied in lead sequestration for perovskite solar cells. PCSS provides robustness and water-resistance, which improves device stability toward water erosion and extreme situations (such as acid, base, salty water, and hot water). PPVI-TFSI exhibited excellent affinity toward lead with adsorption capacity of 516 mg·g-1, which assisted to prevent lead leakage in abandoned devices as proved in the test of wheat germination vividly. PCSS provides a promising solution for complex lead sequestration and management issues, which contribute to the commercialization of perovskite solar cells.

Gut microbiota-derived indole 3-propionic acid partially activates aryl hydrocarbon receptor to promote macrophage phagocytosis and attenuate septic injury.

Sepsis is associated with a high risk of death, and the crosstalk between gut microbiota and sepsis is gradually revealed. Indole 3-propionic acid (IPA) is a gut microbiota-derived metabolite that exerts immune regulation and organ protective effects. However, the role of IPA in sepsis is not clear. In this study, the role of IPA in sepsis-related survival, clinical scores, bacterial burden, and organ injury was assessed in a murine model of cecal ligation and puncture-induced polymicrobial sepsis. Aryl hydrocarbon receptor (AhR) highly specific inhibitor (CH223191) was used to observe the role of AhR in the protection of IPA against sepsis. The effects of IPA on bacterial phagocytosis by macrophages were investigated in vivo and vitro. The levels of IPA in feces were measured and analyzed in human sepsis patients and patient controls. First, we found that gut microbiota-derived IPA was associated with the survival of septic mice. Then, in animal model, IPA administration protected against sepsis-related mortality and alleviated sepsis-induced bacterial burden and organ injury, which was blunted by AhR inhibitor. Next, in vivo and vitro, IPA enhanced the macrophage phagocytosis through AhR. Depletion of macrophages reversed the protective effects of IPA on sepsis. Finally, on the day of ICU admission (day 0), septic patients had significantly lower IPA level in feces than patient controls. Also, septic patients with bacteremia had significantly lower IPA levels in feces compared with those with non-bacteremia. Furthermore, in septic patients, reduced IPA was associated with worse clinical outcomes, and IPA in feces had similar prediction ability of 28-day mortality with SOFA score, and increased the predictive ability of SOFA score. These findings indicate that gut microbiota-derived IPA can protect against sepsis through host control of infection by promoting macrophages phagocytosis and suggest that IPA may be a new strategy for sepsis treatment.

Gut microbiota-derived indole 3-propionic acid protects against radiation toxicity via retaining acyl-CoA-binding protein

BackgroundWe have proved fecal microbiota transplantation (FMT) is an efficacious remedy to mitigate acute radiation syndrome (ARS); however, the mechanisms remain incompletely characterized. Here, we aimed to tease apart the gut microbiota-produced metabolites, underpin the therapeutic effects of FMT to radiation injuries, and elucidate the underlying molecular mechanisms.ResultsFMT elevated the level of microbial-derived indole 3-propionic acid (IPA) in fecal pellets from irradiated mice. IPA replenishment via oral route attenuated hematopoietic system and gastrointestinal (GI) tract injuries intertwined with radiation exposure without precipitating tumor growth in male and female mice. Specifically, IPA-treated mice represented a lower system inflammatory level, recuperative hematogenic organs, catabatic myelosuppression, improved GI function, and epithelial integrity following irradiation. 16S rRNA gene sequencing and subsequent analyses showed that irradiated mice harbored a disordered enteric bacterial pattern, which was preserved after IPA administration. Notably, iTRAQ analysis presented that IPA replenishment retained radiation-reprogrammed protein expression profile in the small intestine. Importantly, shRNA interference and hydrodynamic-based gene delivery assays further validated that pregnane X receptor (PXR)/acyl-CoA-binding protein (ACBP) signaling played pivotal roles in IPA-favored radioprotection in vitro and in vivo.ConclusionsThese evidences highlight that IPA is a key intestinal microbiota metabolite corroborating the therapeutic effects of FMT to radiation toxicity. Owing to the potential pitfalls of FMT, IPA might be employed as a safe and effective succedaneum to fight against accidental or iatrogenic ionizing ARS in clinical settings. Our findings also provide a novel insight into microbiome-based remedies toward radioactive diseases.5xbhwSC1V4FsDQpg8AwjrSVideo abstract.

Effects of cyanobacterial suspensions as bio-fertilizers on growth factors and the essential oil composition of chamomile, Matricaria chamomilla L.

The cyanobacterial species used in this study were collected from medicinal plant beds and were cultured using nitrate free BG-11 medium. As heterocystous cyanobacteria fix atmospheric nitrogen and some of them additionally produce phytohormones, we hypothesized that using a suspension of beneficial cyanobacterial species in the soil of the plant might enhance its growth and would probably also affect the essential oil of this plant. Based on a seedling growth test, the cyanobacterial species Nostoc carneum, Wollea vaginicola and Nostoc punctiforme were selected for a pot trial. A glasshouse experiment with seven replicates was designed to evaluate the effects of the cyanobacterial suspensions on Matricaria chamomilla L. growth and essential oil production. The cyanobacterial suspensions were applied 15 days after planting. Fifty days after flowering the plants were harvested and the plant growth parameters were measured. Additionally, the chemical composition of soil samples from both the treatments and control pots were analyzed. All of the studied cyanobacterial suspensions had a significant effect on the weight of essential oil as well as on root growth. The chamazulene content of the essential oil in plants treated with N. carneum was 26.9% more than in the control. HPLC analysis revealed that the cyanobacterial species used in this experiment were able to produce plant growth–promoting hormones such as indole 3-acetic acid, indole 3-propionic acid and indole 3-butyric acid. There was a significant positive correlation between cyanobacterial IAA and all of the growth factors, as well as some constituents of the essential oil.

The pregnane X receptor and its microbiota-derived ligand indole 3-propionic acid regulate endothelium-dependent vasodilation.

We proposed that circulating metabolites generated by the intestinal microbiota can affect vascular function. One such metabolite, indole 3-propionic acid (IPA), can activate the pregnane X receptor(PXR), a xenobiotic-activated nuclear receptor present in many tissues, including the vascular endothelium. We hypothesized that IPA could regulate vascular function by modulating PXR activity. To test this, Pxr+/+ mice were administered broad-spectrum antibiotics for 2 wk with IPA supplementation. Vascular function was evaluated by bioassay using aorta and pulmonary artery ring tissue from antibiotic-treated Pxr+/+ and Pxr-/-mice, supplemented with IPA, and using aorta tissue maintained in organ culture for 24 h in the presence of IPA. Endothelium-dependent, nitric oxide(NO)-mediated muscarinic and proteinase-activated receptor 2(PAR2)-stimulated vasodilation was assessed. Endothelial nitric oxide synthase (eNOS) abundance was evaluated in intact tissue or in aorta-derived endothelial cell cultures from Pxr+/+ and Pxr-/- mice, and vascular Pxr levels were assessed in tissues obtained from Pxr+/+ mice treated with antibiotics and supplemented with IPA. Antibiotic-treated Pxr+/+ mice exhibited enhanced agonist-induced endothelium-dependent vasodilation, which was phenocopied by tissues from either Pxr-/- or germ-free mice. IPA exposure reduced the vasodilatory responses in isolated and cultured vessels. No effects of IPA were observed for tissues obtained from Pxr-/- mice. Serum nitrate levels were increased in antibiotic-treated Pxr+/+and Pxr-/- mice. eNOS abundance was increased in aorta tissues and cultured endothelium from Pxr-/- mice. PXR stimulation reduced eNOS expression in cultured endothelial cells from Pxr+/+ but not Pxr-/- mice. The microbial metabolite IPA, via the PXR, plays a key role in regulating endothelial function. Furthermore, antibiotic treatment changes PXR-mediated vascular endothelial responsiveness by upregulating eNOS.

Melatonin Treatment Enhances Aβ Lymphatic Clearance in a Transgenic Mouse Model of Amyloidosis.

It has been postulated that inadequate clearance of the amyloid β protein (Aβ) plays an important role in the accumulation of Aβ in sporadic late onset Alzheimer's disease (AD). While the blood brain barrier (BBB) has taken the center stage in processes involving Aβ clearance, little information is available about the role of the lymphatic system. We previously reported that Aβ is cleared through the lymphatic system. We now assessed lymphatic Aβ clearance by treating a mouse model of AD amyloidosis with melatonin, an Aβ aggregation inhibitor and immuno-regulatory neurohormone. To confirm and expand our initial finding that Aβ is cleared through the lymphatic system. Lymphatic clearance of metabolic and cellular "waste" products from the brain into the peripheral lymphatic system has been known for a long time. However, except for our prior report, there is no additional experimental data published about Aβ being cleared into peripheral lymph nodes. For these experiments, we used a transgenic mouse model (Tg2576) that over-expresses a mutant form of the Aβ precursor protein (APP) in the brain. We examined levels of Aβ in plasma and in lymph nodes of transgenic mice as surrogate markers of vascular and lymphatic clearance, respectively. Aβ levels were also measured in the brain and in multiple tissues. Clearance of Aβ peptides through the lymphatic system was confirmed in this study. Treatment with melatonin led to the following changes: 1-A statistically significant increase in soluble monomeric Aβ40 and an increasing trend in Aβ42 in cervical and axillary lymph nodes of treated mice. 2- Statistically significant decreases in oligomeric Aβ40 and a decreasing trend Aβ42 in the brain. The data expands on our prior report that the lymphatic system participates in Aβ clearance from the brain. We propose that abnormalities in Aβ clearance through the lymphatic system may contribute to the development of cerebral amyloidosis. Melatonin and related indole molecules (i.e., indole- 3-propionic acid) are known to inhibit Aβ aggregation although they do not reverse aggregated Aβ or amyloid fibrils. Therefore, these substances should be further explored in prevention trials for delaying the onset of cognitive impairment in high risk populations.

Polyester-based microdisc systems for sustained release of neuroprotective phosphine-borane complexes

Phosphine-borane complexes are recently developed redox-active drugs that are neuroprotective in models of optic nerve injury and radioprotective in endothelial cells. However, a single dose of these compounds is short-lived, necessitating the development of sustained-release formulations of these novel molecules. We screened a library of biodegradable co- and non-block polyester polymer systems for release of incorporated phosphine-borane complexes to evaluate them as drug delivery systems for use in chronic disease. Bis(3-propionic acid methyl ester)phenylphosphine borane complex (PB1) was combined with biodegradable polymers based on poly(D,L-lactide) (PDLLA), poly(L-lactide) (PLLA), poly(caprolactone) (PCL), poly(lactide-co-glycide) (PLGA), or poly(dioxanone-co-caprolactone) (PDOCL) to make polymer microdiscs, and release over time quantified. Of 22 polymer-PB1 formulations tested, 17 formed rigid polymers. Rates of release differed significantly based on the chemical structure of the polymer. PB1 released from PLGA microdiscs released most slowly, with the most linear release in polymers of 60:40 LA:GA, acid endcap, Mn 15 000–25 000 and 75:25 LA:GA, acid endcap, Mn 45 000–55 000. Biodegradable polymer systems can, therefore, be used to produce sustained-release formulations for redox-active phosphine-borane complexes, with PLGA-based systems most suitable for very slow release. The sustained release could enable translation to a clinical neuroprotective strategy for chronic diseases such as glaucoma.

Axonal Degeneration in Retinal Ganglion Cells Is Associated with a Membrane Polarity-Sensitive Redox Process.

Axonal degeneration is a pathophysiological mechanism common to several neurodegenerative diseases. The slow Wallerian degeneration (WldS) mutation, which results in reduced axonal degeneration in the central and peripheral nervous systems, has provided insight into a redox-dependent mechanism by which axons undergo self-destruction. We studied early molecular events in axonal degeneration with single-axon laser axotomy and time-lapse imaging, monitoring the initial changes in transected axons of purified retinal ganglion cells (RGCs) from wild-type and WldS rat retinas using a polarity-sensitive annexin-based biosensor (annexin B12-Cys101,Cys260-N,N'-dimethyl-N-(iodoacetyl)-N'-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) ethylenediamine). Transected axons demonstrated a rapid and progressive change in membrane phospholipid polarity, manifested as phosphatidylserine externalization, which was significantly delayed and propagated more slowly in axotomized WldS RGCs compared with wild-type axons. Delivery of bis(3-propionic acid methyl ester)phenylphosphine borane complex, a cell-permeable intracellular disulfide-reducing drug, slowed the onset and velocity of phosphatidylserine externalization in wild-type axons significantly, replicating the WldS phenotype, whereas extracellular redox modulation reversed the WldS phenotype. These findings are consistent with an intra-axonal redox mechanism for axonal degeneration associated with the initiation and propagation of phosphatidylserine externalization after axotomy.SIGNIFICANCE STATEMENT Axonal degeneration is a neuronal process independent of somal apoptosis, the propagation of which is unclear. We combined single-cell laser axotomy with time-lapse imaging to study the dynamics of phosphatidylserine externalization immediately after axonal injury in purified retinal ganglion cells. The extension of phosphatidylserine externalization was slowed and delayed in Wallerian degeneration slow (WldS) axons and this phenotype could be reproduced by intra-axonal disulfide reduction in wild-type axons and reversed by extra-axonal reduction in WldS axons. These results are consistent with a redox mechanism for propagation of membrane polarity asymmetry in axonal degeneration.

Thermodynamic insight into solvent-effect on structures and antifungal activities of manganese(II) complexes with acylhydrazone

Three manganese(II) complexes, [Mn(HL)(EtOH)2Cl]2 (1), [Mn2(HL)2(EtOH)3(H2O)Cl2]2·[Mn(HL)(EtOH)(H2O)Cl]2·[Mn(HL)(EtOH)2Cl]2·4EtOH (2) and Mn(HL)2·2H2O (3) (H2L=N-(2-propionic acid)-(4-methoxy benzoyl) hydrazone), have been synthesized by self-assembly of MnCl2 with H2L in different ethanol/water systems. To better understand the thermodynamic stability of complexes with diverse structures, theoretical investigation of the electronic structures of the compounds has been carried out using density function theoretical calculations. Isothermal titration calorimetry (ITC) was employed to monitor the interactions between Mn(II) and H2L in different solvents, in which the binding constants (Ka) of the systems are 3.54×104, 3.66×104 and 34.97×104Lmol−1 for 1, 2 and 3, respectively. The thermodynamic calculation results indicate that the self-assembly of 1 and 2 are entropy-dominated spontaneous processes, while that of 3 is an enthalpy-driven one. In addition, solvent-effect on antifungal activity for compounds 1–3 was investigated.

Intracellular disulfide reduction by phosphine-borane complexes: Mechanism of action for neuroprotection

Phosphine-borane complexes are novel cell-permeable drugs that protect neurons from axonal injury in vitro and in vivo. These drugs activate the extracellular signal-regulated kinases 1/2 (ERK1/2) cell survival pathway and are therefore neuroprotective, but do not scavenge superoxide. In order to understand the interaction between superoxide signaling of neuronal death and the action of phosphine-borane complexes, their biochemical activity in cell-free and in vitro assays was studied by electron paramagnetic resonance (EPR) spectrometry and using an intracellular dithiol reporter that becomes fluorescent when its disulfide bond is cleaved. These studies demonstrated that bis(3-propionic acid methyl ester) phenylphosphine-borane complex (PB1) and (3-propionic acid methyl ester) diphenylphosphine-borane complex (PB2) are potent intracellular disulfide reducing agents which are cell permeable. EPR and pharmacological studies demonstrated reducing activity but not scavenging of superoxide. Given that phosphine-borane complexes reduce cell injury from mitochondrial superoxide generation but do not scavenge superoxide, this implies a mechanism where an intracellular superoxide burst induces downstream formation of protein disulfides. The redox-dependent cleavage of the disulfides is therefore a novel mechanism of neuroprotection.

Borane-protected phosphines are redox-active radioprotective agents for endothelial cells

Exposure to radiation can damage endothelial cells in the irradiated area via the production of reactive oxygen species. We synthesized phosphine–borane complexes that reduce disulfide bonds and had previously been shown to interfere with redox-mediated signaling of cell death. We hypothesized that this class of drugs could interfere with the downstream effects of oxidative stress after irradiation and rescue endothelial cells from radiation damage. Cultured bovine aortic endothelial cells were plated for clonogenic assay prior to exposure to varying doses of irradiation from a 137Cs irradiator and treated with various concentrations of bis(3-propionic acid methyl ester)phenylphosphine borane complex (PB1) at different time points. The clone-forming ability of the irradiated cells was assessed seven days after irradiation. We compared the radioprotective effects of PB1 with the aminothiol radioprotectant WR1065 and known superoxide scavengers. PB1 significantly protected bovine aortic endothelial cells from radiation damage, particularly when treated both before and after radiation. The radioprotection with 1µM PB1 corresponded to a dose-reduction factor of 1.24. Radioprotection by PB1 was comparable to the aminothiol WR1065, but was significantly less toxic and required much lower concentrations of drug (1µM vs. 4mM, respectively). Superoxide scavengers were not radioprotective in this paradigm, indicating the mechanisms for both loss of clonogenicity and PB1 radioprotection are independent of superoxide signaling. These data demonstrate that PB1 is an effective redox-active radioprotectant for endothelial cells in vitro, and is radioprotective at a concentration approximately 4 orders of magnitude lower than the aminothiol WR1065 with less toxicity.

Symbiotic Bacterial Metabolites Regulate Gastrointestinal Barrier Function via the Xenobiotic Sensor PXR and Toll-like Receptor 4

Intestinal microbial metabolites are conjectured to affect mucosal integrity through an incompletely characterized mechanism. Here we showed that microbial-specific indoles regulated intestinal barrier function through the xenobiotic sensor, pregnane X receptor (PXR). Indole 3-propionic acid (IPA), in the context of indole, is a ligand for PXR in vivo, and IPA downregulated enterocyte TNF-α while it upregulated junctional protein-coding mRNAs. PXR-deficient (Nr1i2(-/-)) mice showed a distinctly "leaky" gut physiology coupled with upregulation of the Toll-like receptor (TLR) signaling pathway. These defects in the epithelial barrier were corrected in Nr1i2(-/-)Tlr4(-/-) mice. Our results demonstrate that a direct chemical communication between the intestinal symbionts and PXR regulates mucosal integrity through a pathway that involves luminal sensing and signaling by TLR4.

Symbiotic bacterial metabolites regulate GI barrier function via PXR and TLR4 (MUC4P.852)

Abstract Intestinal microbial metabolites affect mucosal integrity through incompletely characterized mechanisms. Here we identify microbial specific indoles that regulate intestinal barrier function through the xenobiotic sensor, pregnane X receptor (PXR). Indole 3-propionic acid (IPA), in the context of indole, serves as a ligand for PXR and down-regulates enterocyte TNF-α while up-regulating junctional protein-coding mRNAs. Pxr-/- mice exhibit a distinctly “leaky” gut physiology coupled with up-regulation of the Toll-like receptor (TLR) signaling pathway. These defects in the epithelial barrier are corrected in Pxr-/-/Tlr4-/- double-knockout mice. To validate that IPA drives the anti-inflammatory response directly via PXR, we exposed intestinal commensal-depleted Pxr+/+ and Pxr-/- mice to live (IPA-producing) or heat-killed (non-IPA producing) C. sporogenes preceding indomethacin exposure (toxic small intestinal injury model). There was a significant reduction in histologic injury and mucosal myeloperoxidase (MPO) enzyme activity. The intestinal mucosa exposed to live (as opposed to heat-killed) C. sporogenes had significant induction of PXR target gene (Ugt1a1). These effects were absent in Pxr-/- mice. Our results demonstrate that a direct chemical communication between the intestinal symbionts and PXR regulates mucosal integrity through a pathway which involves luminal sensing and signaling by TLR4.

Synthesis, Crystal Structure of a 2-D Copper (II) Complex Based on Mixed Organic Ligands

A novel copper (II) ternary complex with the formula [Cu (HL) (Py) (H2O)] (H3L˭N-(2-Propionic Acid)-salicyloyl hydrazone, Py = pyridine) has been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The Cu atom in the complex is five-coordinated by one N and two O atoms of HL and one N atom from pyridine, these four atoms are located at the bottom of the square-pyramid, the other coordinating atom is O atom of H2O locating at the apical position. Intermolecular hydrogen bonds link the complex to form a 2D super molecule network.

Synthesis, Characterization, and DNA-Binding Studies of Lanthanide(III) Complexes Ln(H2L) · (HL) · 0.5(bipy)·nH2O1

A series of lanthanide(III) complexes Ln(H2L) · (HL) · 0.5(bipy)·nH2O (where Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, and H3L = N-(2-propionic acid)-salicyloyl hydrazone, bipy = 2,2′-dipyridine) have been synthesized in ethanol-water mixture and characterized. The DNA-binding properties of these complexes were searched for the interaction with CT-DNA by electronic absorption titration and emission titration. The results showed that the interaction between Nd(III) complex and CT-DNA by surface/electrostatic binding, while all the other complexes can bind to calf-thymus DNA mainly by intercalation mode.