Broad-spectrum in vitro activity of macrophage infectivity potentiator inhibitors against Gram-negative bacteria and Leishmania major.

BACKGROUND: The macrophage infectivity potentiator (Mip) protein, which belongs to the immunophilin superfamily, is a peptidyl-prolyl cis/trans isomerase (PPIase) enzyme. Mip has been shown to be important for virulence in a wide range of pathogenic microorganisms. It has previously been demonstrated that small-molecule compounds designed to target Mip from the Gram-negative bacterium Burkholderia pseudomallei bind at the site of enzymatic activity of the protein, inhibiting the in vitro activity of Mip. OBJECTIVES: In this study, co-crystallography experiments with recombinant B. pseudomallei Mip (BpMip) protein and Mip inhibitors, biochemical analysis and computational modelling were used to predict the efficacy of lead compounds for broad-spectrum activity against other pathogens. METHODS: Binding activity of three lead compounds targeting BpMip was verified using surface plasmon resonance spectroscopy. The determination of crystal structures of BpMip in complex with these compounds, together with molecular modelling and in vitro assays, was used to determine whether the compounds have broad-spectrum antimicrobial activity against pathogens. RESULTS: Of the three lead small-molecule compounds, two were effective in inhibiting the PPIase activity of Mip proteins from Neisseria meningitidis, Klebsiella pneumoniae and Leishmania major. The compounds also reduced the intracellular burden of these pathogens using in vitro cell infection assays. CONCLUSIONS: These results indicate that Mip is a novel antivirulence target that can be inhibited using small-molecule compounds that prove to be promising broad-spectrum drug candidates in vitro. Further optimization of compounds is required for in vivo evaluation and future clinical applications.

Short- and Long-Term Effects of Rehabilitation after Perimesencephalic Subarachnoid Hemorrhage.

In about 25% of patients with spontaneous subarachnoid hemorrhage (SAH), a bleeding source cannot be identified during radiological diagnostics. Generally, the outcome of perimesencephalic or prepontine (PM) SAH is known to be significantly better than after non-PM SAH. Data about long-term follow-up concerning physical and mental health are scarce, so this study is reports on long-term results. We measured the influence of PM SAH on a quality-of-life modified Rankin (mRs) scale after six months. For long-term follow-up, a SF-36 questionnaire was used. Questionnaires were sent out between 18 and 168 months after ictus. In 37 patients, a long-term follow-up was available (up to 14 years after SAH). Data detected with the SF-36 questionnaire are compared to reference applicability to the standard population. In total, 37 patients were included for further analysis and divided in 2 subgroups; 13 patients (35%) received subsequent rehabilitation after clinical stay and 24 (65%) did not. In the short-term outcome, a significant improvement from discharge until follow-up was identified in patients with subsequent rehabilitation, but not in the matched pair group without rehabilitation. When PM SAH was compared to the standard population, a reduction in quality of life was identified in physical items (role limitations because of physical health problems, physical functioning) as well as in psychological items (role limitations because of emotional problems). Subsequent rehabilitation on PM SAH patients probably leads to an increase in independence and better mRs. While better mRs was shown at discharge in patients without subsequent rehabilitation, the mRs of rehabilitants was nearly identical after rehabilitation. Patients with good mRs also reached high levels of health-related quality of life (HRQoL) without rehabilitation. Thus, subsequent rehabilitation needs to be encouraged on an individual basis. Indication criteria for subsequent rehabilitation should be defined in further studies to improve patient treatment and efficiency in health care.

Non-aneurysmal non-perimesencephalic subarachnoid hemorrhage: effect of rehabilitation at short-term and in a prospective study of long-term follow-up.

BACKGROUND: A recently published prospective study identified an impaired outcome of patients with non-perimesencephalic (NPM) subarachnoid hemorrhage (SAH). Our objective was to analyze the long-term outcome of patients with subsequent rehabilitation after NPM SAH. METHODS: A comparison of patients with NPM SAH receiving subsequent in-patient rehabilitation was done at discharge (using the modified Rankin scale (mRS)), short-term outcome after 6 months (mRS), and prospectively using a questionnaire (short-form health survey with 36 questions (SF-36)), which was sent to 66 patients. RESULTS: Thirty-seven patients answered the SF-36, on average 6.3 years after ictus (range 1.5-14 years). After NPM SAH, the mRS is impaired. Patients with subsequent rehabilitation had a significant better improvement until short-term follow-up. Until long-term outcome, the psychological items were non-significantly reduced, whereas all physical items (physical functioning, role limitations because of physical health problems, bodily pain, and general health perceptions) were significantly decreased compared to the standard population. In patients with subsequent rehabilitation, all items were only non-significantly reduced. About 16% of the patients developed secondary neurological and/or psychiatric diseases. CONCLUSIONS: The quality of life (QoL) is decreased after NPM SAH. In the long-term follow-up, a significant reduction in physical items was identified. Due to subsequent in-patient rehabilitation after NPM SAH, the impairment can be improved significantly until short-term follow-up. Whereas patients with NPM SAH had a significantly decreased QoL at long-term follow-up, for patients with rehabilitation, the QoL was only slightly (non-significantly) reduced. Therefore, patients should receive subsequent rehabilitation after NPM SAH to improve the functional short-term outcome (mRS) and long-term QoL. www.clinicaltrials.gov (Identifier No. NCT02334657).

Dualsteric muscarinic antagonists--orthosteric binding pose controls allosteric subtype selectivity.

Bivalent ligands of G protein-coupled receptors have been shown to simultaneously either bind to two adjacent receptors or to bridge different parts of one receptor protein. Recently, we found that bivalent agonists of muscarinic receptors can simultaneously occupy both the orthosteric transmitter binding site and the allosteric vestibule of the receptor protein. Such dualsteric agonists display a certain extent of subtype selectivity, generate pathway-specific signaling, and in addition may allow for designed partial agonism. Here, we want to extend the concept to bivalent antagonism. Using the phthal- and naphthalimide moieties, which bind to the allosteric, extracellular site, and atropine or scopolamine as orthosteric building blocks, both connected by a hexamethonium linker, we were able to prove a bitopic binding mode of antagonist hybrids for the first time. This is demonstrated by structure-activity relationships, site-directed mutagenesis, molecular docking studies, and molecular dynamics simulations. Findings revealed that a difference in spatial orientation of the orthosteric tropane moiety translates into a divergent M2/M5 subtype selectivity of the corresponding bitopic hybrids.

Molecular alliance-from orthosteric and allosteric ligands to dualsteric/bitopic agonists at G protein coupled receptors.

Cell-membrane-spanning G protein coupled receptors (GPCRs) belong to the most important therapeutic target structures. Endogenous transmitters bind from the outer side of the membrane to the "orthosteric" binding site either deep in the binding pocket or at the extracellular N-terminal end of the receptor protein. Exogenous modulators that utilize a different, "allosteric", binding site unveil a pathway to receptor subtype-selectivity. However, receptor activation through the orthosteric area is often more powerful. Recently there has been evidence that orthosteric/allosteric, in other words "dualsteric", hybrid compounds unite subtype selectivity and receptor activation. These "bitopic" modulators channelreceptor activation and subsequent intracellular signaling into a subset of possible routes. This concept offers access to GPCR modulators with an unprecedented receptor-subtype and signaling selectivity profile and, as a consequence, to drugs with fewer side effects.

The allosteric vestibule of a seven transmembrane helical receptor controls G-protein coupling.

Seven transmembrane helical receptors (7TMRs) modulate cell function via different types of G proteins, often in a ligand-specific manner. Class A 7TMRs harbour allosteric vestibules in the entrance of their ligand-binding cavities, which are in the focus of current drug discovery. However, their biological function remains enigmatic. Here we present a new strategy for probing and manipulating conformational transitions in the allosteric vestibule of label-free 7TMRs using the M(2) acetylcholine receptor as a paradigm. We designed dualsteric agonists as 'tailor-made' chemical probes to trigger graded receptor activation from the acetylcholine-binding site while simultaneously restricting spatial flexibility of the receptor's allosteric vestibule. Our findings reveal for the first time that a 7TMR's allosteric vestibule controls the extent of receptor movement to govern a hierarchical order of G-protein coupling. This is a new concept assigning a biological role to the allosteric vestibule for controlling fidelity of 7TMR signalling.

A small-molecule inhibitor of Nipah virus envelope protein-mediated membrane fusion.

Nipah virus (NiV), a highly pathogenic paramyxovirus, causes respiratory disease in pigs and severe febrile encephalitis in humans with high mortality rates. On the basis of the structural similarity of viral fusion (F) proteins within the family Paramyxoviridae, we designed and tested 18 quinolone derivatives in a NiV and measles virus (MV) envelope protein-based fusion assay beside evaluation of cytotoxicity. We found five compounds successfully inhibiting NiV envelope protein-induced cell fusion. The most active molecules (19 and 20), which also inhibit the syncytium formation induced by infectious NiV and show a low cytotoxicity in Vero cells, represent a promising lead quinolone-type compound structure. Molecular modeling indicated that compound 19 fits well into a particular protein cavity present on the NiV F protein that is important for the fusion process.