Anti-Inflammatory Activity of a Potent, Selective Leukotriene A4 Hydrolase Inhibitor in Comparison with the 5-Lipoxygenase Inhibitor Zileuton

ABSTRACT Leukotriene A 4 hydrolase (LTA 4 H) catalyzes production of the proinflammatory lipid mediator, leukotriene (LT) B 4 , which is implicated in a number of inflammatory diseases. We have identified a potent and selective inhibitor of both the epoxide hydrolase and aminopeptidase activities of recombinant human LTA 4 H (IC 50 , approximately 10 nM). In a murine model of arachidonic acid-induced ear inflammation, the LTA 4 H inhibitor, JNJ-26993135 (1-[4-(benzothiazol-2-yloxy)-benzyl]-piperidine-4-carboxylic acid), dose-dependently inhibited ex vivo LTB 4 production in blood, in parallel with dose-dependent inhibition of neutrophil influx (ED 50 , 1-3 mg/kg) and ear edema. In murine whole blood and in zymosan-induced peritonitis, JNJ-26993135 selectively inhibited LTB 4 production, without affecting cysteinyl leukotriene production, while maintaining or increasing production of the anti-inflammatory mediator, lipoxin (LX) A 4 . The 5-lipoxygenase (5-LO) inhibitor zileuton showed inhibition of LTB 4 , LTC 4 , and LXA 4 production. Although zileuton inhibited LTB 4 production in the peritonitis model more effectively than the LTA 4 H inhibitor, the influx of neutrophils into the peritoneum after 1 and 2 h was significantly higher in zileuton-versus JNJ-26993135-treated animals. This difference may have been mediated by the increased LXA 4 levels in the presence of the LTA 4 H inhibitor. The selective inhibition of LTB 4 production by JNJ-26993135, while increasing levels of the anti-inflammatory mediator, LXA 4 , may translate to superior therapeutic efficacy versus 5-LO or 5-LO-activating protein inhibitors in LTB 4 -mediated inflammatory diseases

Prochlorococcus extracellular vesicles: molecular composition and adsorption to diverse microbes

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biller, S. J., Lundeen, R. A., Hmelo, L. R., Becker, K. W., Arellano, A. A., Dooley, K., Heal, K. R., Carlson, L. T., Van Mooy, B. A. S., Ingalls, A. E., & Chisholm, S. W. Prochlorococcus extracellular vesicles: molecular composition and adsorption to diverse microbes. Environmental Microbiology. (2022), https://doi.org/10.1111/1462-2920.15834.Extracellular vesicles are small (~50–200 nm diameter) membrane-bound structures released by cells from all domains of life. While vesicles are abundant in the oceans, their functions, both for cells themselves and the emergent ecosystem, remain a mystery. To better characterize these particles – a prerequisite for determining function – we analysed the lipid, protein, and metabolite content of vesicles produced by the marine cyanobacterium Prochlorococcus. We show that Prochlorococcus exports a diverse array of cellular compounds into the surrounding seawater enclosed within discrete vesicles. Vesicles produced by two different strains contain some materials in common, but also display numerous strain-specific differences, reflecting functional complexity within vesicle populations. The vesicles contain active enzymes, indicating that they can mediate extracellular biogeochemical reactions in the ocean. We further demonstrate that vesicles from Prochlorococcus and other bacteria associate with diverse microbes including the most abundant marine bacterium, Pelagibacter. Together, our data point toward hypotheses concerning the functional roles of vesicles in marine ecosystems including, but not limited to, possibly mediating energy and nutrient transfers, catalysing extracellular biochemical reactions, and mitigating toxicity of reactive oxygen species.This work was funded by grants from the National Science Foundation (OCE-1356460 to S.W.C.) and the Simons Foundation (SCOPE Award ID 329108 to B.A.S.V.M., A.E.I., S.W.C.; Life Sciences Project Award ID 337262, S.W.C.; Simons Award ID 385428 to A.E.I. and 598819 to K.R.H.). K.W.B was supported by the Postdoctoral Scholarship Programme at the Woods Hole Oceanographic Institution. R.A.L was partially supported by a postdoctoral fellowship from the Swiss National Science Foundation

Stress response of a marine ammonia-oxidizing archaeon informs physiological status of environmental populations.

High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their high affinity for ammonia, efficient carbon fixation, and copper (Cu)-centric respiratory system. However, little is known about their response to nutrient stress. We therefore used global transcriptional and proteomic analyses to characterize the response of a model AOA, Nitrosopumilus maritimus SCM1, to ammonia starvation, Cu limitation and Cu excess. Most predicted protein-coding genes were transcribed in exponentially growing cells, and of ~74% detected in the proteome, ~6% were modified by N-terminal acetylation. The general response to ammonia starvation and Cu stress was downregulation of genes for energy generation and biosynthesis. Cells rapidly depleted transcripts for the A and B subunits of ammonia monooxygenase (AMO) in response to ammonia starvation, yet retained relatively high levels of transcripts for the C subunit. Thus, similar to ammonia-oxidizing bacteria, selective retention of amoC transcripts during starvation appears important for subsequent recovery, and also suggests that AMO subunit transcript ratios could be used to assess the physiological status of marine populations. Unexpectedly, cobalamin biosynthesis was upregulated in response to both ammonia starvation and Cu stress, indicating the importance of this cofactor in retaining functional integrity during times of stress

Ruthenium Complexes are pH-Activated Metallo Prodrugs (pHAMPs) with Light-Triggered Selective Toxicity Toward Cancer Cells

Metallo prodrugs that take advantage of the inherent acidity surrounding cancer cells have yet to be developed. We report a new class of pH-activated metallo prodrugs (pHAMPs) that are activated by light- and pH-triggered ligand dissociation. These ruthenium complexes take advantage of a key characteristic of cancer cells and hypoxic solid tumors (acidity) that can be exploited to lessen the side effects of chemotherapy. Five ruthenium complexes of the type [(N,N)₂Ru­(PL)]²⁺ were synthesized, fully characterized, and tested for cytotoxicity in cell culture (<b>1</b>_<b>A</b>: N,N = 2,2′-bipyridine (bipy) and PL, the photolabile ligand, = 6,6′-dihydroxybipyridine (6,6′-dhbp); <b>2</b>_<b>A</b>: N,N = 1,10-phenanthroline (phen) and PL = 6,6′-dhbp; <b>3</b>_<b>A</b>: N,N = 2,3-dihydro-[1,4]­dioxino­[2,3-<i>f</i>]­[1,10]­phenanthroline (dop) and PL = 6,6′-dhbp; <b>4</b>_<b>A</b>: N,N = bipy and PL = 4,4′-dimethyl-6,6′-dihydroxybipyridine (dmdhbp); <b>5</b>_<b>A</b>: N,N = 1,10-phenanthroline (phen) and PL = 4,4′-dihydroxybipyridine (4,4′-dhbp). The thermodynamic acidity of these complexes was measured in terms of two p<i>K</i>_a values for conversion from the acidic form (<b>X</b>_<b>A</b>) to the basic form (<b>X</b>_<b>B</b>) by removal of two protons. Single-crystal X-ray diffraction data is discussed for <b>2</b>_<b>A</b>, <b>2</b>_<b>B</b>, <b>3</b>_<b>A</b>, <b>4</b>_<b>B</b>, and <b>5</b>_<b>A</b>. All complexes except <b>5</b>_<b>A</b> showed measurable photodissociation with blue light (λ = 450 nm). For complexes <b>1</b>_<b>A</b>–<b>4</b>_<b>A</b> and their deprotonated analogues (<b>1</b>_<b>B</b>–<b>4</b>_<b>B</b>), the protonated form (at pH 5) consistently gave faster rates of photodissociation and larger quantum yields for the photoproduct, [(N,N)₂Ru­(H₂O)₂]²⁺. This shows that low pH can lead to greater rates of photodissociation. Cytotoxicity studies with <b>1</b>_<b>A</b>–<b>5</b>_<b>A</b> showed that complex <b>3</b>_<b>A</b> is the most cytotoxic complex of this series with IC₅₀ values as low as 4 μM (with blue light) versus two breast cancer cell lines. Complex <b>3</b>_<b>A</b> is also selectively cytotoxic, with sevenfold higher toxicity toward cancerous versus normal breast cells. Phototoxicity indices with <b>3</b>_<b>A</b> were as high as 120, which shows that dark toxicity is avoided. The key difference between complex <b>3</b>_<b>A</b> and the other complexes tested appears to be higher uptake of the complex as measured by inductively coupled plasma mass spectrometry, and a more hydrophobic complex as compared to <b>1</b>_<b>A</b>, which may enhance uptake. These complexes demonstrate proof of concept for dual activation by both low pH and blue light, thus establishing that a pHAMP approach can be used for selective targeting of cancer cells

Health-status outcomes with invasive or conservative care in coronary disease

BACKGROUND In the ISCHEMIA trial, an invasive strategy with angiographic assessment and revascularization did not reduce clinical events among patients with stable ischemic heart disease and moderate or severe ischemia. A secondary objective of the trial was to assess angina-related health status among these patients. METHODS We assessed angina-related symptoms, function, and quality of life with the Seattle Angina Questionnaire (SAQ) at randomization, at months 1.5, 3, and 6, and every 6 months thereafter in participants who had been randomly assigned to an invasive treatment strategy (2295 participants) or a conservative strategy (2322). Mixed-effects cumulative probability models within a Bayesian framework were used to estimate differences between the treatment groups. The primary outcome of this health-status analysis was the SAQ summary score (scores range from 0 to 100, with higher scores indicating better health status). All analyses were performed in the overall population and according to baseline angina frequency. RESULTS At baseline, 35% of patients reported having no angina in the previous month. SAQ summary scores increased in both treatment groups, with increases at 3, 12, and 36 months that were 4.1 points (95% credible interval, 3.2 to 5.0), 4.2 points (95% credible interval, 3.3 to 5.1), and 2.9 points (95% credible interval, 2.2 to 3.7) higher with the invasive strategy than with the conservative strategy. Differences were larger among participants who had more frequent angina at baseline (8.5 vs. 0.1 points at 3 months and 5.3 vs. 1.2 points at 36 months among participants with daily or weekly angina as compared with no angina). CONCLUSIONS In the overall trial population with moderate or severe ischemia, which included 35% of participants without angina at baseline, patients randomly assigned to the invasive strategy had greater improvement in angina-related health status than those assigned to the conservative strategy. The modest mean differences favoring the invasive strategy in the overall group reflected minimal differences among asymptomatic patients and larger differences among patients who had had angina at baseline

Initial invasive or conservative strategy for stable coronary disease

BACKGROUND Among patients with stable coronary disease and moderate or severe ischemia, whether clinical outcomes are better in those who receive an invasive intervention plus medical therapy than in those who receive medical therapy alone is uncertain. METHODS We randomly assigned 5179 patients with moderate or severe ischemia to an initial invasive strategy (angiography and revascularization when feasible) and medical therapy or to an initial conservative strategy of medical therapy alone and angiography if medical therapy failed. The primary outcome was a composite of death from cardiovascular causes, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. A key secondary outcome was death from cardiovascular causes or myocardial infarction. RESULTS Over a median of 3.2 years, 318 primary outcome events occurred in the invasive-strategy group and 352 occurred in the conservative-strategy group. At 6 months, the cumulative event rate was 5.3% in the invasive-strategy group and 3.4% in the conservative-strategy group (difference, 1.9 percentage points; 95% confidence interval [CI], 0.8 to 3.0); at 5 years, the cumulative event rate was 16.4% and 18.2%, respectively (difference, 121.8 percentage points; 95% CI, 124.7 to 1.0). Results were similar with respect to the key secondary outcome. The incidence of the primary outcome was sensitive to the definition of myocardial infarction; a secondary analysis yielded more procedural myocardial infarctions of uncertain clinical importance. There were 145 deaths in the invasive-strategy group and 144 deaths in the conservative-strategy group (hazard ratio, 1.05; 95% CI, 0.83 to 1.32). CONCLUSIONS Among patients with stable coronary disease and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of ischemic cardiovascular events or death from any cause over a median of 3.2 years. The trial findings were sensitive to the definition of myocardial infarction that was used