Race Against the Court: The Supreme Court and Minorities in Contemporary America

A Review of Race Against the Court: The Supreme Court and Minorities in Contemporary America by Girardeau A. Span

Magnetization transfer contrast MRI in GFP-tagged live bacteria

Green fluorescent protein (GFP) is a widely utilized molecular reporter of gene expression. However, its use in in vivo imaging has been restricted to transparent tissue mainly due to the tissue penetrance limitation of optical imaging. Magnetization transfer contrast (MTC) is a magnetic resonance imaging (MRI) methodology currently utilized to detect macromolecule changes such as decrease in myelin and increase in collagen content. MTC MRI imaging was performed to detect GFP in both in vitro cells and in an in vivo mouse model to determine if MTC imaging could be used to detect infection from Pseudomonas aeruginosa in murine tissues. It was demonstrated that the approach produces values that are protein specific and concentration dependent. This method provides a valuable, non-invasive imaging tool to study the impact of novel antibacterial therapeutics on bacterial proliferation and perhaps viability within the host system, and could potentially suggest the modulation of bacterial gene expression within the host when exposed to such compounds

Identification of Anti-virulence Compounds That Disrupt Quorum-Sensing Regulated Acute and Persistent Pathogenicity

Etiological agents of acute, persistent, or relapsing clinical infections are often refractory to antibiotics due to multidrug resistance and/or antibiotic tolerance. Pseudomonas aeruginosa is an opportunistic Gram-negative bacterial pathogen that causes recalcitrant and severe acute chronic and persistent human infections. Here, we target the MvfR-regulated P. aeruginosa quorum sensing (QS) virulence pathway to isolate robust molecules that specifically inhibit infection without affecting bacterial growth or viability to mitigate selective resistance. Using a whole-cell high-throughput screen (HTS) and structure-activity relationship (SAR) analysis, we identify compounds that block the synthesis of both pro-persistence and pro-acute MvfR-dependent signaling molecules. These compounds, which share a benzamide-benzimidazole backbone and are unrelated to previous MvfR-regulon inhibitors, bind the global virulence QS transcriptional regulator, MvfR (PqsR); inhibit the MvfR regulon in multi-drug resistant isolates; are active against P. aeruginosa acute and persistent murine infections; and do not perturb bacterial growth. In addition, they are the first compounds identified to reduce the formation of antibiotic-tolerant persister cells. As such, these molecules provide for the development of next-generation clinical therapeutics to more effectively treat refractory and deleterious bacterial-human infections

In-Vivo Expression Profiling of Pseudomonas aeruginosa Infections Reveals Niche-Specific and Strain-Independent Transcriptional Programs

Pseudomonas aeruginosa is a threatening, opportunistic pathogen causing disease in immunocompromised individuals. The hallmark of P. aeruginosa virulence is its multi-factorial and combinatorial nature. It renders such bacteria infectious for many organisms and it is often resistant to antibiotics. To gain insights into the physiology of P. aeruginosa during infection, we assessed the transcriptional programs of three different P. aeruginosa strains directly after isolation from burn wounds of humans. We compared the programs to those of the same strains using two infection models: a plant model, which consisted of the infection of the midrib of lettuce leaves, and a murine tumor model, which was obtained by infection of mice with an induced tumor in the abdomen. All control conditions of P. aeruginosa cells growing in suspension and as a biofilm were added to the analysis. We found that these different P. aeruginosa strains express a pool of distinct genetic traits that are activated under particular infection conditions regardless of their genetic variability. The knowledge herein generated will advance our understanding of P. aeruginosa virulence and provide valuable cues for the definition of prospective targets to develop novel intervention strategies

Race Against the Court: The Supreme Court and Minorities in Contemporary America

A Review of Race Against the Court: The Supreme Court and Minorities in Contemporary America by Girardeau A. Span

Polypharmacology Approaches against the Pseudomonas aeruginosa MvfR Regulon and Their Application in Blocking Virulence and Antibiotic Tolerance

International audiencePseudomonas aeruginosa is an important nosocomial pathogen that is frequently recalcitrant to available antibiotics, underlining the urgent need for alternative therapeutic options against this pathogen. Targeting virulence functions is a promising alternative strategy as it is expected to generate less-selective resistance to treatment compared to antibiotics. Capitalizing on our nonligand-based benzamide-benzimidazole (BB) core structure compounds reported to efficiently block the activity of the P. aeruginosa multiple virulence factor regulator MvfR, here we report the first class of inhibitors shown to interfere with PqsBC enzyme activity, responsible for the synthesis of the MvfR activating ligands HHQ and PQS, and the first to target simultaneously MvfR and PqsBC activity. The use of these compounds reveals that inhibiting PqsBC is sufficient to block P. aeruginosa's acute virulence functions, as the synthesis of MvfR ligands is inhibited. Our results show that MvfR remains the best target of this QS pathway, as we show that antagonists of this target block both acute and persistence-related functions. The structural properties of the compounds reported in this study provide several insights that are instrumental for the design of improved MvfR regulon inhibitors against both acute and persistent P. aeruginosa infections. Moreover, the data presented offer the possibility of a polypharmacology approach of simultaneous silencing two targets in the same pathway. Such a combined antivirulence strategy holds promise in increasing therapeutic efficacy and providing alternatives in the event of a single target's resistance development

MvfR-regulon inhibitors rescue PA14-macrophage cytotoxicity.

<p>PA14-induced killing of Raw264.7 macrophage cells was determined minus and plus 100 µM inhibitor. Error bars represent mean +/− SEM of at least 3 replicates. Differences between PA14 + vehicle and the samples PA14 + M64, PA14 + M62, PA14 + M59, PA14 + M51, PA14 + M50, or PA14 + M27 are statistically significant (<i>p</i><0.01, one way ANOVA, Dunnett's test). Differences between MvfR and MvfR + M64 (<i>p</i>>0.05) or vehicle and M64 (<i>p</i>>0.05) are not statistically significant (unpaired t test). Notably, M64 does not alter cytotoxicity of <i>mvfR</i> cells, and is itself non-cytotoxic.</p

M64 reduces pyocyanin production in <i>P. aeruginosa</i> clinical multi-drug resistant strains.

<p><b>a.</b> Quantitative pyocyanin production in multi-drug resistant clinical <i>P. aeruginosa</i> isolates plus (red) and minus (black) 5 µM M64. A representative image of qualitative pyocyanin production, visible as green media, in PA14 culture +/− M64, is shown above the histogram. <b>b.</b> Antibiotic resistance profile of <i>P. aeruginosa</i> clinical strains and their respective isolation sites from infected patients. Amik. = amikacin, Gent. = gentamycin, Mero. = meropenem, Pip. = piperacin, Tobra. = tobramycin, Cefe. = cefepime, Aze. = azetromycin, Cip. = ciprofloxacin. R = resistant; I = intermediate; S = sensitive.</p