The small-molecule formyl peptide receptor biased agonist, compound 17b, is a vasodilator and anti-inflammatory in mouse precision-cut lung slices.

BACKGROUND AND PURPOSE: Pulmonary arterial hypertension (PAH), a rare fatal disorder characterised by inflammation, vascular remodelling and vasoconstriction. Current vasodilator therapies reduce pulmonary arterial pressure but not mortality. The G-protein coupled formyl peptide receptors (FPRs) mediates vasodilatation and resolution of inflammation, actions possibly beneficial in PAH. We investigated dilator and anti-inflammatory effects of the FPR biased agonist compound 17b in pulmonary vasculature using mouse precision-cut lung slices (PCLS). EXPERIMENTAL APPROACH: PCLS from 8-week-old male and female C57BL/6 mice, intrapulmonary arteries were pre-contracted with 5-HT for concentration-response curves to compound 17b and 43, and standard-of-care drugs, sildenafil, iloprost and riociguat. Compound 17b-mediated relaxation was assessed with FPR antagonists or inhibitors and in PCLS treated with TNF-α or LPS. Cytokine release from TNF-α- or LPS-treated PCLS ± compound 17b was measured. KEY RESULTS: Compound 17b elicited concentration-dependent vasodilation, with potencies of iloprost > compound 17b = riociguat > compound 43 = sildenafil. Compound 17b was inhibited by the FPR1 antagonist cyclosporin H but not by soluble guanylate cyclase, nitric oxide synthase or cyclooxygenase inhibitors. Under inflammatory conditions, the efficacy and potency of compound 17b were maintained, while iloprost and sildenafil were less effective. Additionally, compound 17b inhibited secretion of PAH-relevant cytokines via FPR2. CONCLUSIONS AND IMPLICATIONS: Vasodilation to compound 17b but not standard-of-care vasodilators, is maintained under inflammatory conditions, with additional inhibition of PAH-relevant cytokine release. This provides the first evidence that targeting FPR, with biased agonist, simultaneously targets vascular function and inflammation, supporting the development of FPR-based pharmacotherapy to treat PAH.

Tryptophan-metabolizing gut microbes regulate adult neurogenesis via the aryl hydrocarbon receptor.

While modulatory effects of gut microbes on neurological phenotypes have been reported, the mechanisms remain largely unknown. Here, we demonstrate that indole, a tryptophan metabolite produced by tryptophanase-expressing gut microbes, elicits neurogenic effects in the adult mouse hippocampus. Neurogenesis is reduced in germ-free (GF) mice and in GF mice monocolonized with a single-gene tnaA knockout (KO) mutant Escherichia coli unable to produce indole. External administration of systemic indole increases adult neurogenesis in the dentate gyrus in these mouse models and in specific pathogen-free (SPF) control mice. Indole-treated mice display elevated synaptic markers postsynaptic density protein 95 and synaptophysin, suggesting synaptic maturation effects in vivo. By contrast, neurogenesis is not induced by indole in aryl hydrocarbon receptor KO (AhR-/-) mice or in ex vivo neurospheres derived from them. Neural progenitor cells exposed to indole exit the cell cycle, terminally differentiate, and mature into neurons that display longer and more branched neurites. These effects are not observed with kynurenine, another AhR ligand. The indole-AhR-mediated signaling pathway elevated the expression of ß-catenin, Neurog2, and VEGF-α genes, thus identifying a molecular pathway connecting gut microbiota composition and their metabolic function to neurogenesis in the adult hippocampus. Our data have implications for the understanding of mechanisms of brain aging and for potential next-generation therapeutic opportunities.

Neurogenesis and prolongevity signaling in young germ-free mice transplanted with the gut microbiota of old mice.

The gut microbiota evolves as the host ages, yet the effects of these microbial changes on host physiology and energy homeostasis are poorly understood. To investigate these potential effects, we transplanted the gut microbiota of old or young mice into young germ-free recipient mice. Both groups showed similar weight gain and skeletal muscle mass, but germ-free mice receiving a gut microbiota transplant from old donor mice unexpectedly showed increased neurogenesis in the hippocampus of the brain and increased intestinal growth. Metagenomic analysis revealed age-sensitive enrichment in butyrate-producing microbes in young germ-free mice transplanted with the gut microbiota of old donor mice. The higher concentration of gut microbiota-derived butyrate in these young transplanted mice was associated with an increase in the pleiotropic and prolongevity hormone fibroblast growth factor 21 (FGF21). An increase in FGF21 correlated with increased AMPK and SIRT-1 activation and reduced mTOR signaling. Young germ-free mice treated with exogenous sodium butyrate recapitulated the prolongevity phenotype observed in young germ-free mice receiving a gut microbiota transplant from old donor mice. These results suggest that gut microbiota transplants from aged hosts conferred beneficial effects in responsive young recipients.

The gut microbiota influences skeletal muscle mass and function in mice.

The functional interactions between the gut microbiota and the host are important for host physiology, homeostasis, and sustained health. We compared the skeletal muscle of germ-free mice that lacked a gut microbiota to the skeletal muscle of pathogen-free mice that had a gut microbiota. Compared to pathogen-free mouse skeletal muscle, germ-free mouse skeletal muscle showed atrophy, decreased expression of insulin-like growth factor 1, and reduced transcription of genes associated with skeletal muscle growth and mitochondrial function. Nuclear magnetic resonance spectrometry analysis of skeletal muscle, liver, and serum from germ-free mice revealed multiple changes in the amounts of amino acids, including glycine and alanine, compared to pathogen-free mice. Germ-free mice also showed reduced serum choline, the precursor of acetylcholine, the key neurotransmitter that signals between muscle and nerve at neuromuscular junctions. Reduced expression of genes encoding Rapsyn and Lrp4, two proteins important for neuromuscular junction assembly and function, was also observed in skeletal muscle from germ-free mice compared to pathogen-free mice. Transplanting the gut microbiota from pathogen-free mice into germ-free mice resulted in an increase in skeletal muscle mass, a reduction in muscle atrophy markers, improved oxidative metabolic capacity of the muscle, and elevated expression of the neuromuscular junction assembly genes Rapsyn and Lrp4 Treating germ-free mice with short-chain fatty acids (microbial metabolites) partly reversed skeletal muscle impairments. Our results suggest a role for the gut microbiota in regulating skeletal muscle mass and function in mice.

Synthesis of Unique Phosphazane Macrocycles via Steric Activation of C-N Bonds.

Herein we describe that oxidation reactions of the dimeric cyclophosphazanes, [{P(µ-NR)}2(µ-NR)]2, R = tBu (1), to produce a series of diagonally dioxidized products P4(µ-N tBu)6E2 [E = O (2), S (3), and Se (4)] and tetraoxidized frameworks. The latter display an unexpected C-N bond activation and cleavage to produce a series of novel phosphazane macrocyclic arrangements containing newly formed N-H bonds. Macromolecules P4(µ-N tBu)4(µ-NH)2O4 (5) and P4(µ-N tBu)3(µ-NH)3E4, E = S (6) and Se (7), dicleaved and tricleaved products, respectively, are rare examples of dimeric macrocycles containing NH bridging groups. Our theoretical and experimental studies illustrate that the extent to which these C-N bonds are cleaved can be controlled by modification of steric parameters in their synthesis, by adjusting either the steric bulk of the substituents in the parent framework or the size of the chalcogen element introduced during the oxidation process. Our findings represent new synthetic pathways for the synthesis of otherwise-elusive macrocycle arrangements within the phosphazane family.

Steric C-N bond activation on the dimeric macrocycle [{P(µ-NR)}2(µ-NR)]2.

Dimeric cyclophosphazanes [{P(µ-NR)}2(µ-NR)]2 [R = (t)Bu ( 1) and iPr ( 3)] were oxidized with elemental selenium. During these reactions an unexpected C­N bond cleavage and N­H bond formation occurred. Compound 1 produced P4(µ-N(t)Bu)3(µ-NH)3Se4 ( 2) where three tBu groups were lost in the form of isobutylene. In contrast, during the oxidation of the less sterically hindered 3, the resulting product, P4(µ-N(i)Pr)5(µ-NH)Se4 ( 4), showed only one substituent loss. Theoretical studies confirmed the steric nature of the driving force underlying the different outcomes.

Synthesis and Hydrolytic Studies on the Air-Stable [(4-CN-PhO)(E)P(µ-N(t)Bu)]2 (E = O, S, and Se) Cyclodiphosphazanes.

Reaction of 4-CN-PhOH with [ClP(µ-N(t)Bu)]2 (1) (2:1 ratio) in the presence of Et3N produced the functionalized cyclodiphosph(III/III)azane [(4-CN-PhO)P(µ-N(t)Bu)]2 (2). Oxidation of 2 produced cyclodiphosph(V/V)azanes [(4-CN-PhO)(E)P(µ-N(t)Bu)]2 [E = O (3), S (4), and Se (5)]. This is the first example of a series of cyclodiphosph(V/V)azane derivatives obtained from a single cyclophosph(III/III)azane precursor where all the accessible chalcogen oxidized products are air-stable over prolonged periods of time.

Contemporary management of renal trauma.

In the management of renal trauma, surgical exploration inevitably leads to nephrectomy in all but a few specialized centers. With current management options, the majority of hemodynamically stable patients with renal injuries can be successfully managed nonoperatively. Improved radiographic techniques and the development of a validated renal injury scoring system have led to improved staging of injury severity that is relatively easy to monitor. This article reviews a multidisciplinary approach to facilitate the care of patients with renal injury.

Hip3 interacts with the HIRA proteins Hip1 and Slm9 and is required for transcriptional silencing and accurate chromosome segregation.

The fission yeast HIRA proteins Hip1 and Slm9 are members of an evolutionarily conserved family of histone chaperones that are implicated in nucleosome assembly. Here we have used single-step affinity purification and mass spectrometry to identify factors that interact with both Hip1 and Slm9. This analysis identified Hip3, a previously uncharacterized 187-kDa protein, with similarity to S. cerevisiae Hir3. Consistent with this, cells disrupted for hip3+ exhibit a range of growth defects that are similar to those associated with loss of Hip1 and Slm9. These include temperature sensitivity, a cell cycle delay, and synthetic lethality with cdc25-22. Furthermore, genetic analysis also indicates that disruption of hip3+ is epistatic with mutation of hip1+ and slm9+. Mutation of hip3+ alleviates transcriptional silencing at several heterochromatic loci, including in the outer (otr) centromeric repeats, indicating that Hip3 is required for the integrity of pericentric heterochromatin. As a result, loss of Hip3 function leads to high levels of minichromosome loss and an increased frequency of lagging chromosomes during mitosis. Importantly, the function of Hip1, Slm9, and Hip3 is not restricted to constitutive heterochromatic loci, since these proteins also repress the expression of a number of genes, including the Tf2 retrotransposons.