Insights into the antimicrobial effects of tafenoquine against Enterococcus and its biofilms.

AIM: The purpose of this study is to assess the in vitro antimicrobial and anti-biofilm effects of the anti-protozoal agent tafenoquine (TAF) on Enterococcus and elucidate its underlying mode of action. METHODS AND RESULTS: The present work investigated the susceptibility of TAF on 3 type strains and 11 clinical isolates of enterococci. The results indicated that TAF exhibited powerful antimicrobial activity against both of Enterococcus faecalis and Enterococcus faecium with minimum inhibitory and bactericidal concentrations ranging from 8 to 16 µg ml-1. Meanwhile, biofilm inhibition and eradication assays showed that TAF exhibited potent anti-biofilm activity against E. faecalis ATCC 29212 and E. faecium ATCC 19434. Ultra-microscopic observations revealed significant changes in bacterial morphology and structure caused by TAF, particularly for the disruption of plasma membrane. Mechanistic investigations also revealed that TAF altered both membrane permeability and potential while also impacting adenosine triphosphate production as well as reactive oxygen species generation. In addition, no detectable cytotoxicity of TAF on human cells was observed at concentrations near the minimal inhibitory concentration. CONCLUSIONS: In summary, this study confirmed that TAF could effectively inhibit Enterococcus as well as its biofilm formation.

Simeprevir restores the anti-Staphylococcus activity of polymyxins.

Methicillin-resistant Staphylococcus aureus (MRSA) infection poses a severe threat to global public health due to its high mortality. Currently, polymyxins are mainly used for the treatment of Gram-negative bacterial-related infection, while exhibiting limited antibacterial activities against Staphylococcus aureus (S. aureus). However, the combination of antibiotics with antibiotic adjuvants is a feasible strategy for the hard-treated infection and toxicity reducing. We will investigate the antibacterial activity of simeprevir (SIM), which treated for genotype 1 and 4 chronic hepatitis C, combined with polymyxins against MRSA through high-throughput screening technology. In our study, the synergistic antibacterial effect of SIM and polymyxins against S. aureus in vitro was found by checkerboard assay and time-growth curve. The cytotoxicity of SIM combined with polymyxin B sulfate [PB(S)] or polymyxin E (PE) in vitro was evaluated using CCK-8, human RBC hemolysis and scratch assays. In addition, we investigated the eradication of biofilm formation of S. aureus by biofilm inhibition assay and the killing of persister cells. Moreover, we evaluated the therapeutic effect and in vivo toxicity of the combination against MRSA in murine subcutaneous abscess model. Furthermore, it was preliminarily found that SIM significantly enhanced the destruction of MRSA membrane by SYTOX Green and DISC3(5) probes. In summary, these results reveal that the therapy of SIM combined with polymyxins (especially PE) is promising for the treatment of MRSA infection.

Membrane tethering of CreER decreases uninduced cell labeling and cytotoxicity while maintaining recombination efficiency.

Genetic lineage tracing is indispensable to unraveling the origin, fate, and plasticity of cells. However, the intrinsic leakiness in the CreER-loxP system raises concerns on data interpretation. Here, we reported the generation of a novel dual inducible CreER-loxP system with superior labeling characteristics. This two-component system consists of membrane localized CreER (mCreER: CD8α-FRB-CS-CreER) and TEV protease (mTEVp: CD8α-FKBP-TEVp), which are fusion proteins incorporated with the chemically induced dimerization machinery. Rapamycin and tamoxifen induce sequential dimerization of FKBP and FRB, cleavage of CreER from the membrane, and translocation into the nucleus. The labeling leakiness in Ad293 cells reduced dramatically from more than 70% to less than 5%. This tight labeling feature depends largely on the association of mCreER with HSP90, which conceals the TEV protease cutting site between FRB and CreER and thus preventing uninduced cleavage of the membrane-tethering CreER. Membrane-bound CreER also diminished significantly cytotoxicity. Our studies showed mCreER under the control of the rat insulin promoter increased labeling specificity in MIN6 islet beta-cells. Viability and insulin secretion of MIN6 cells remained intact. Our results demonstrate that this novel system can provide more stringent temporal and spatial control of gene expression and will be useful in cell fate probing.

Glucocorticoid Production in Lymphoid Organs: Acute Effects of Lipopolysaccharide in Neonatal and Adult Mice.

Glucocorticoids (GCs) are critical modulators of the immune system. The hypothalamic-pituitary-adrenal (HPA) axis regulates circulating GC levels and is stimulated by endotoxins. Lymphoid organs also produce GCs; however, it is not known how lymphoid GC levels are regulated in response to endotoxins. We assessed whether an acute challenge of lipopolysaccharide (LPS) increases lymphoid levels of progesterone and GCs, and expression of steroidogenic enzymes and key HPA axis components (eg, corticotropin-releasing hormone [CRH], adrenocorticotropic hormone [ACTH]). We administered LPS (50 µg/kg intraperitoneally) or vehicle control to male and female C57BL/6J neonatal (postnatal day [PND] 5) and adult (PND90) mice and collected blood, bone marrow, thymus, and spleen 4 hours later. We measured progesterone, 11-deoxycorticosterone, corticosterone, and 11-dehydrocorticosterone via liquid chromatography-tandem mass spectrometry. We measured gene expression of key steroidogenic enzymes (Cyp11b1, Hsd11b1, and Hsd11b2) and HPA axis components (Crh, Crhr1, Pomc, and Mc2r) via quantitative polymerase chain reaction. At PND5, LPS induced greater increases in steroid levels in lymphoid organs than in blood. In contrast, at PND90, LPS induced greater increases in steroid levels in blood than in lymphoid organs. Steroidogenic enzyme transcripts were present in all lymphoid organs, and LPS altered steroidogenic enzyme expression predominantly in the spleen. Lastly, we detected transcripts of key HPA axis components in all lymphoid organs, and there was an effect of LPS in the spleen. Taken together, these data suggest that LPS regulates GC production by lymphoid organs, similar to its effects on the adrenal glands, and the effects of LPS might be mediated by local expression of CRH and ACTH.

Rhamnolipid pretreatment enhances methane production from two-phase anaerobic digestion of waste activated sludge.

In this work, a rhamnolipid (RL) pretreatment technology was proposed to promote methane production from two-phase anaerobic digestion of waste activated sludge. In the first phase (i.e., acidogenic phase), the WAS hydrolysis and acidogenesis were significantly enhanced after RL pretreatment for 4 day, under which the concentration of soluble protein and the short-chain fatty acids (SCFA) in the presence of RL at 0.04 g/g TSS was respectively 2.50 and 5.02 times higher than that without RL pretreatment. However, methane production was inhibited in the presence of RL. In the second phase (i.e., methanogenic phase), batch biochemical methane potential tests suggested that the addition of RL is effective in promoting anaerobic methane production. With an increase of RL dosage from 0 to 0.04 g/g TSS, the cumulative methane yield increased from 100.42 ± 3.01 to 168.90 ± 5.42 mL. Although the added RL could be utilized to produce methane, it was not the major contributor to the enhancement of methane yield. Further analysis revealed that total cumulative yield from the entire two-phase anaerobic digestion (sum of the yield of the acidogenic phase and methanogenic phase) increased from 113.42 ± 3.56 to 164.18 ± 5.20 mL when RL dosage increased from 0 to 0.03 g/g TSS, indicating that the addition of RL induced positive effect on the methane production of the entire two-phase anaerobic digestion. The enzyme activity analysis showed that although higher dosages of RL still inhibited the microorganisms related to methanogenesis to some extends in the methanogenic phase, the inhibitory effect was significantly weakened compared to the acidogenic phase. Microbial analysis revealed that RL reduced the abundance of Candidatus_Methanofastidiosum sp. while increased the abundance of Methanosaeta sp., causing the major methanogenesis pathway to change from hydrogenotrophic to aceticlastic. Moreover, the community of hydrolytic microbes and acidogens was shifted in the direction that is conducive to hydrolysis-acidogenesis. The findings reported not only expand the application field of RL, but also may provide supports for sustainable operation of wastewater treatment plants (WWTPs).

Efficacy of chuanxiong ding tong herbal formula granule in the treatment and prophylactic of migraine patients: a randomized, double-blind, multicenter, placebo-controlled trial.

Objective. To evaluate the efficacy of traditional Chinese herbal ChuanXiong Ding Tong herbal formula granule (CXDT-HFG) for migraine patients with "the Syndrome of Liver Wind and Blood Stasis." Methods. 150 migraine patients were recruited and assigned randomly in a double-blind, placebo-controlled study to receive CXDT-HFG (n = 99) plus necessary analgesics, or placebo (n = 51) plus necessary analgesics for 16 weeks (12 weeks' intervention and 4 weeks' follow up). Outcome measures included migraine days, frequency of migraine attacks, analgesics consumption for acute treatment, and the proportion of responders as well as the visual analogue scale (VAS) scores and intensity for pain. Results. Compared with the placebo group, the CXDT-HFG group showed significant reduction in migraine days and attacks frequency at week 12 and follow-up period (P < 0.05) as well as in the reduction of VAS scores at follow-up period.There was significant difference in the proportion of responders between the two groups at follow-up period (P = 0.014). However there were no significant differences between the two groups in analgesics consumption (P > 0.05). Conclusion. CXDT-HFG was more effective than placebo in decreasing days of migraine attacks, frequency, VAS scores, and relieving pain intensity for migraine patients.