A uniform step size, low-voltage piezoelectric motor with dual-channel force loop.

Recently, a variety of piezoelectric motors with remarkable performance have appeared. However, due to the hysteresis effect of piezoelectrics and stress return errors within the mechanical structures, the existing piezoelectric motors still face some challenges, such as inconsistent step size, high working voltage, and considerable speed variances during upward vs downward movements even under identical driving voltage signals. Here, we introduce a novel low-voltage piezoelectric motor with a dual-channel force loop based on piezoelectric stacks, in which each slider has two force loops connected with other sliders and the internal elastic preload element is installed, which can effectively address these issues. This new type of piezoelectric motor has low working voltage (starting voltage is only 0.8 V, significantly lower than that of conventional piezoelectric motors), large driving force, uniform step size, and excellent linearity.

Clinical characteristics of radiation-induced optic neuropathy: A single-center retrospective study.

Purpose: To observe the clinical and imaging characteristics of radiation-induced optic neuropathy (RION). Methods: We retrospectively reviewed the clinical data of 43 patients (69 eyes) who were diagnosed with RION at the Chinese PLA General Hospital from 2010 to 2021. Results: The latency from radiotherapy to onset of visual loss ranged from 1 to 132 (36.33 â€‹± â€‹30.48) months. Optic disc pallor and optic disc edema were found in 27.0% (10/37) and 8.1% (3/37) of the eyes, respectively, within 2 months. After treatment, the best corrected visual acuity (BCVA) was restored in 24.6% (17/69) of the eyes and the final BCVA improved in 13.0% (9/69) of the eyes. An 82.5% (33/40) of the eyes with magnetic resonance imaging (MRI) showed enhancement of the affected optic nerve, mostly (69.7%) in the intracranial segment, and 36.4% (12/33) of the eyes with expansion and T2-high signals also showed enhancement of the affected optic nerve. The superior retinal nerve fiber layer (RNFL) and the outer circle superior quadrant (OS) of the inner limiting membrane to retinal pigment epithelium (ILM-RPE) layer thinned significantly during the first month. The center of the ILM-RPE layer thickened significantly during the first two months and the inner circle temporal quadrant (IT) of the ILM-RPE layer thickened significantly from the third to sixth month. The RNFL thinned significantly after 6 months except for the temporal quadrant, and the average inner circle superior quadrant (IS) and outer circle of the ILM-RPE layer thinned significantly after 6 months. There was no significant difference between hyperbaric oxygen therapy (HBOT) and high-dose intravenous methylprednisolone (IVMP) therapy in improving BCVA recovery or final BCVA (P â€‹> â€‹0.05). Conclusions: The structural damage of the RNFL and ILM-RPE layer occurred during the first month, the RNFL showed progressive thinning during the follow-up period, while the ILM-RPE layer showed thinning during the first month, thickening from the third to sixth month, and thinning after 6 months. There was a discrete region of enhancement of the optic nerve, often with expansion and high-T2 signals on MRI. HBOT and high-dose IVMP therapy were hardly effective for treating RION in the non-acute stage.

Upregulation of C-X-C motif chemokine 12 in the spinal cord alleviated the symptoms of experimental autoimmune encephalomyelitis in Lewis rats.

Background: C-X-C motif chemokine 12 (CXCL12) is a chemokine that performs many functions. Studies have shown that CXCL12 can aggravate inflammatory symptoms in the central nervous system (CNS). Evidence also indicates that CXCL12 can promote the repair of myelin sheaths in the CNS in experimental autoimmune encephalomyelitis (EAE). Here, we investigated the function of CXCL12 in CNS inflammation by upregulating CXCL12 in the spinal cord and subsequently inducing EAE. Materials and methods: CXCL12 upregulation in the spinal cords of Lewis rats was induced by the injection of adeno-associated virus 9 (AAV9)/eGFP-P2A-CXCL12 after intrathecal catheter implantation. Twenty-one days after AAV injection, EAE was induced and clinical score was collected; Immunofluorescence staining, WB and LFB-PAS staining were used to evaluate the effect of CXCL12 upregulation. In the in vitro study, oligodendrocyte precursor cells (OPCs) were harvested, cultured with CXCL12 and AMD3100, and subjected to immunofluorescence staining for functional assessment. Results: CXCL12 was upregulated in the lumbar enlargement of the spinal cord by AAV injection. In each stage of EAE, upregulation of CXCL12 significantly alleviated clinical scores by inhibiting leukocyte infiltration and promoting remyelination. In contrast, the addition of AMD3100, which is a CXCR4 antagonist, inhibited the effect of CXCL12. In vitro, 10 ng/ml CXCL12 promoted the differentiation of OPCs into oligodendrocytes. Conclusion: AAV-mediated upregulation of CXCL12 in the CNS can alleviate the clinical signs and symptoms of EAE and significantly decrease the infiltration of leukocytes in the peak stage of EAE. CXCL12 can promote the maturation and differentiation of OPCs into oligodendrocytes in vitro. These data indicate that CXCL12 effectively promotes remyelination in the spinal cord and decreases the signs and symptoms of EAE.

ACT001 Relieves NMOSD Symptoms by Reducing Astrocyte Damage with an Autoimmune Antibody.

Neuromyelitis optica spectrum disorder (NMOSD) is a central nervous system inflammatory demyelinating disease, the pathogenesis of which involves autoantibodies targeting the extracellular epitopes of aquaporin-4 on astrocytes. We neutralized the AQP4-IgG from NMOSD patient sera using synthesized AQP4 extracellular epitope peptides and found that the severe cytotoxicity produced by aquaporin-4 immunoglobin (AQP4-IgG) could be blocked by AQP4 extracellular mimotope peptides of Loop A and Loop C in astrocyte protection and animal models. ACT001, a natural compound derivative, has shown anti-tumor activity in various cancers. In our study, the central nervous system anti-inflammatory effect of ACT001 was investigated. The results demonstrated the superior astrocyte protection activity of ACT001 at 10 µM. Furthermore, ACT001 decreases the behavioral score in the mouse NMOSD model, which was not inferior to Methylprednisolone Sodium Succinate, the first-line therapy of NMOSD in clinical practice. In summary, our study showed that astrocytes are protected by specific peptides, or small molecular drugs, which is a new strategy for the treatment of NMOSD. It is possible for ACT001 to be a promising therapy for NMOSD.

Serial analyses of clinical spectra and outcomes in Chinese women with pregnancy-induced optic neuritis.

Objective: This study aimed to investigate the clinical spectra and outcomes in pregnancy-related optic neuritis (ON). Methods: We analyzed the clinical subtype and prognosis of women with pregnancy-related ON in the neuro-ophthalmology department of the First Medical Center at the Chinese PLA General Hospital from January 2014 to December 2019. Results: A total of 54 patients, including 21 (38.9%) with idiopathic ON (ION), 27 (50.0%) with aquaporin-4 (AQP4)-ON, and 6 (11.6%) with myelin oligodendrocyte glycoprotein (MOG)-ON, who experienced 58 informative pregnancies and 67 episodes of pregnancy-related ON were assessed. Among the ON attacks, there were 11 (16.4%) during pregnancy and 56 (83.6%) within 1 year postpartum (PP1) or after abortion, including 33 (49.3%) in the first trimester. In total, 14 (25.9%) patients with ON onset before pregnancy had a higher relapse rate during PP1 than within 1 year before pregnancy (p = 0.021), and 24 (85.7%) eyes with ION and nine (100%) with MOG-ON had significantly better visual outcomes (p ≥ 0.5) than those with AQP4-ON (14, 35%) (p < 0.001 and p < 0.001, respectively). Two AQP4-ON patients had premature birth and low baby weight, respectively. There were no birth defects or stillbirths. Conclusion: The significantly increased relapse rate and numerous cases of ON after pregnancy suggest that delivery adversely affects the course of ON.

Leber's hereditary optic neuropathy companied with multiple-related diseases.

Objective: To elucidate the clinical, radiologic characteristics of Leber's hereditary optic neuropathy (LHON) associated with the other diseases. Materials and methods: Clinical data were retrospectively collected from hospitalized patients with LHON associated with the other diseases at the Neuro-Ophthalmology Department at the Chinese People's Liberation Army General Hospital (PLAGH) from December 2014 to October 2018. Results: A total of 13 patients, 24 eyes (10 men and 3 women; mean age, 30.69 ± 12.76 years) with LHON mitochondrial DNA (mtDNA) mutations, were included in the cohort. 14502(5)11778(4)11778 &11696(1)12811(1)11696(1)3460(1). One patient was positive for aquaporin-4 antibody (AQP4-Ab), and two were positive for myelin oligodendrocyte glycoprotein antibody (MOG-Ab). Three patients were associated with idiopathic optic neuritis (ON). Two patients were with compression optic neuropathy. Three patients were with the central nervous system (CNS) diseases. One patient was with proliferative diabetic retinopathy (PDR) and one with idiopathic orbital inflammatory syndrome (IOIS). At the onset, visual acuity (VA) in eighteen eyes was below 0.1, one eye was 0.5, five eyes were above 0.5, while VA in sixteen eyes was below a 0.1 outcome, three eyes experienced moderate vision loss. MRI images showed T2 lesions and enhancement in nine patients who received corticosteroids treatment; additional immune modulators treatment was performed on two patients. None of the patients had relapse during the follow-up time. Conclusion: Leber's hereditary optic neuropathy can be accompanied with multiple-related diseases, especially different subtypes of ON, which were also exhibited with IOIS and compression optic neuropathy for the first time in this cohort. This condition may be a distinct entity with an unusual clinical and therapeutic profile.

FSP1, a novel KEAP1/NRF2 target gene regulating ferroptosis and radioresistance in lung cancers.

In the study of "A targetable CoQ-FSP1 axis drives ferroptosis- and radiation-resistance in KEAP1 inactive lung cancers" which was published earlier in Nature Communications, the authors have identified a novel KEAP1/NRF2 target gene, FSP1, and demonstrated that FSP1 plays an essential role in NRF2-mediated ferroptosis resistance and radioresistance in KEAP1-deficient lung cancer cells. Currently, many NRF2 target genes have been found to participate in the regulation of ferroptosis, and exactly which one plays a dominant role seems unclear. This study proposes that FSP1 is the key effector in NRF2-mediated ferroptosis resistance and radioresistance in KEAP-deficient lung cancer cells, as we discussed in the manuscript.

Shionone-Targeted Pneumolysin to Ameliorate Acute Lung Injury Induced by Streptococcus pneumoniae In Vivo and In Vitro.

Streptococcus pneumoniae (S. pneumoniae), as a Gram-positive bacterium, can cause severe bacterial pneumonia, and result in high morbidity and mortality in infected people. Meanwhile, isolated drug-resistant S. pneumoniae is growing, which raises concerns about strategies for combatting S. pneumoniae infection. To disturb S. pneumoniae pathogenicity and its drug-resistance, developing novel anti-infective strategies or compounds is urgent. In this study, the anti-infective effect of shionone was explored. A minimum inhibitory concentration (MIC) assay and growth curve determination were performed to evaluate the effect of the tetracyclic triterpenoid compound shionone against S. pneumoniae. Hemolysis tests, western blotting, oligomerization inhibition assays, and molecular docking were carried out to explore the anti-infective mechanism of shionone. Moreover, the protective effect of shionone was also confirmed in a mousepneumonia model. The results showed that the excellent hemolytic inhibitory activity of shionone was observed at less than 8 µg/mL. Meanwhile, shionone could disturb the oligomerization of pneumolysin (PLY) but did not interfere with PLY expression at less than 4 µg/mL. Molecular docking suggested that shionone targeted the ASP-59, ILE-60, THR-57, PHE-344, and ASN-346 amino acid sites to reduce S. pneumoniae pathogenicity. Furthermore, shionone alleviated lung histopathologic injury and decreased lung bacterial colonization in vivo. The above results showed that shionone could bind to the PLY active pocket under the concentrations of 8 µg/mL and neutralize PLY hemolysis activity to reduce S. pneumoniae pathogenicity in vitro and in vivo.

Efficacy of Plasma Exchange Treatment for Demyelinating Optic Neuritis Associated with Various Serum Antibodies: A Prospective Cohort Study.

INTRODUCTION: To evaluate the value of plasma exchange (PE) for patients with three subtypes of demyelinating optic neuritis (ON): aquaporin-4 (AQP4) antibody-positive ON (AQP4-ON), myelin oligodendrocyte glycoprotein (MOG) antibody-positive ON (MOG-ON), and AQP4 and MOG double-antibody-seronegative ON (D-ON). METHODS: A single-center prospective study compared the logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) at most severe onset, 1 day before intravenous high-dose methylprednisolone (IVMP) treatment, 1 day before PE treatment, after five-cycles of PE therapy, and at 1-, 3-, and 6-month follow-up visits. The proportions of eyes in each visual outcome category were also compared. Logistic regression and a receiver operating characteristic curve were used to analyze predicted factors for VA improvement. RESULTS: A total of 124 ON attacks of 122 patients were included. No significant differences were found in BCVA (P = 0.659) before and after PE therapy for 22 D-ON attacks, but VA improved in two of six MOG-ON patients. In 95 AQP4-ON patients suffering 96 attacks, the mean logMAR BCVA markedly improved and was steadily maintained after five-cycles of PE treatments (adjusted P < 0.001), with VA exhibiting a significantly increasing trend (adjusted P = 0.001) after PE treatment. The combination of the number of previous ON episodes and the time window to PE treatment showed accuracy of 74.7% for predicting an improvement in BCVA score ≥ 2 levels. In addition, a combination of logMAR VA before PE and the time window to PE treatment resulted in 83.4% accuracy in predicting whether VA would regain 1.0 logMAR. CONCLUSION: PE therapy effectively improves visual outcomes for AQP4-ON patients, but offers limited value for D-ON patients. Early initiation greatly increases likelihood of achieving VA improvement.

Vision Prognosis and Associated Factors of Optic Neuritis in Dependence of Glial Autoimmune Antibodies.

PURPOSE: To assess the visual prognosis of optic neuritis (ON) in dependence of the glial autoimmune antibody status and associated factors. DESIGN: Longitudinal observational cohort study. METHODS: Patients with ON and measurements of serum concentrations of glial autoantibodies were consecutively and longitudinally examined with a minimal follow-up of 3 months. Patients with multiple sclerosis and double seronegative results were excluded. RESULTS: The study included 529 patients (aquaporin-4 immunoglobulin [AQP4-IgG] seropositive, n = 291; myelin oligodendrocyte glycoprotein immunoglobulin [MOG-IgG] seropositive, n = 112; double-seronegative, n = 126) with 1022 ON episodes (AQP4-IgG seropositive, n = 550; MOG-IgG seropositive, n=254; double-seronegative, n = 218). Prevalence of severe vision loss (best-corrected visual acuity [BCVA] ≤20/200 at the end of follow-up) was higher (P < .001) in the AQP4-IgG group (236/550; 42.9%) than in the seronegative group (68/218; 31.2%) and in the MOG-IgG group (15/254; 5.9%). Prevalence of good vision recovery (BCVA≥20/40) was higher (P < .001) in the MOG-IgG group (229/254; 90.2%) than in the seronegative group (111/218; 50.9%) and in the AQP4-IgG group (236/550; 42.9%). In multivariable logistic analysis, higher prevalence of severe vision loss was associated with AQP4-IgG seropositivity (odds ratio [OR] 1.66; 95% CI 1.14, 2.43; P = .008), male sex (OR 1.97, 95% CI 1.33, 2.93; P < .001), age at ON onset >45 years (OR 1.93, 95% CI 1.35, 2.77; P < .001), nadir vision ≤20/200 (OR 14.11, 95% CI 6.54, 36.93; P < .001), and higher number of recurrences (OR 1.35, 95% CI 1.14, 1.61; P = .001). Higher prevalence of good vision outcome was associated with MOG-IgG seropositivity (OR 8.13, 95% CI 4.82, 14.2; P < .001), age at ON onset <18 years (OR 1.78, 95% CI 1.18, 2.71; P = .006), nadir visual acuity ≥20/40 (OR 4.03; 95% CI 1.45, 14.37; P = .015), and lower number of recurrences (OR 0.60; 95% CI 0.50, 0.72; P < .001). CONCLUSION: Severe vision loss (prevalence in the AQP4-IgG group, MOG-IgG group, and seronegative group: 42.9%, 5.9%, and 31.2%, respectively) was associated with AQP4-IgG seropositivity, male gender, older age at onset, worse nadir vision, and higher number of recurrences.

Clinical predictive factors for diagnosis of MOG-IgG and AQP4-IgG related paediatric optic neuritis: a Chinese cohort study.

BACKGROUND: Different glial-autoantibodies-related paediatric optic neuritis (ON) are associated with different clinical characteristics and prognosis that require different treatments. Because glial autoantibody detection is not available in some parts of the world and there is often a delay in obtaining results, clinical factors that can be used to predict the subtype of paediatric ON are needed. METHODS: This was a single-centre retrospective cohort study. Children who presented with their first ON attack and with complete clinical data were included in the analysis. Single and multiple parameters for predicting paediatric myelin oligodendrocyte glycoprotein immunoglobin-associated ON (MOG-ON) and aquaporin-4 immunoglobin-related ON (AQP4-ON) were calculated. RESULTS: 78 paediatric patients had their first ON attack from January 2016 to December 2019, of whom 69 were included in the final analysis, including 33 MOG-ON cases, 17 AQP4-ON cases and 19 Seronegative-ON cases. For predicting paediatric MOG-ON, the most sensitive predictors were 'male or optic disc swelling (ODS) or bilateral' (sensitivity 0.97 (95% CI 0.82 to 1.00)) and 'follow-up visual acuity (VA) ≤0.1 logMAR or ODS' (sensitivity 0.97 (95% CI 0.82 to 1.00)), and the most specific factor was 'Age ≤11 y and simultaneous CNS involvement' (specificity 0.97 (95% CI 0.84 to 1.00)). For predicting paediatric AQP4-ON, the most sensitive predictor was 'Female or without ODS' (sensitivity 1.00 (95% CI 0.77 to 1.00)), and the most specific factors were Neurological history (sensitivity 0.94 (95% CI 0.83 to 0.98)) and follow-up VA >1.0 logMAR (sensitivity 0.96 (95% CI 0.86 to 0.99)). CONCLUSION: According to our data from a Chinese paediatric cohort, using multiple parameters increases the sensitivity and specificity of diagnosing paediatric MOG-ON and AQP4-ON. These can assist clinicians in diagnosing and treating paediatric ON when glial autoantibody status is not available.

Quercetin impairs Streptococcus pneumoniae biofilm formation by inhibiting sortase A activity.

Biofilm formation mediated by sortase A (srtA) is important for bacterial colonisation and resistance to antibiotics. Thus, the inhibitor of SrtA may represent a promising agent for bacterial infection. The structure of Streptococcus pneumoniae D39 srtA has been characterised by crystallisation. Site-directed mutagenesis was used for the determination of the key residues for the activity of S. pneumoniae D39 srtA. An effective srtA inhibitor, quercetin, and its mechanism was further identified using srtA activity inhibition assay and molecular modelling. In this study, the crystal structure of S. pneumoniae D39 srtA has been solved and shown to contain a unique domain B. Additionally, its transpeptidase activity was evaluated in vitro. Based on the structure, we identified Cys207 as the catalytic residue, with His141 and Arg215 serving as binding sites for the peptide substrate. We found that quercetin can specifically compete with the natural substrate, leading to a significant decrease in the catalytic activity of this enzyme. In cells co-cultured with this small molecule inhibitor, NanA cannot anchor to the cell wall effectively, and biofilm formation and biomass decrease significantly. Interestingly, when we supplemented cultures with sialic acid, a crucial signal for pneumococcal coloniation and the invasion of the host in the co-culture system, biofilm loss did not occur. This result indicates that quercetin inhibits biofilm formation by affecting sialic acid production. In conclusion, the inhibition of pneumococcal srtA by the small molecule quercetin offers a novel strategy for pneumococcal preventative therapy.

Oligopeptide Targeting Sortase A as Potential Anti-infective Therapy for Staphylococcus aureus.

Sortase A (SrtA)-catalyzed anchorage of surface proteins in most Gram-positive bacteria is indispensable for their virulence, suggesting that this transpeptidase is a promising target for antivirulence therapy. Here, an oligopeptide, LPRDA, was identified as an effective inhibitor of SrtA via virtual screening based on the LPXTG substrate sequence, and it was found to inhibit SrtA activity in vitro and in vivo (IC50 = 10.61 µM) by competitively occupying the active site of SrtA. Further, the oligopeptide treatment had no anti-Staphylococcus aureus activity, but it provided protection against S. aureus-induced mastitis in a mouse model. These findings indicate that the oligopeptide could be used as an effective anti-infective agent for the treatment of infection caused by S. aureus or other Gram-positive bacteria via the targeting of SrtA.

Morin Attenuates Streptococcus suis Pathogenicity in Mice by Neutralizing Suilysin Activity.

Streptococcus suis, a Gram-positive pathogen, is widely recognized as an important agent of swine infection, and it is also known to cause a variety of zoonoses, such as meningitis, polyarthritis and pneumonia. Suilysin (SLY), an extracellular pore-forming toxin that belongs to the cholesterol-dependent cytolysin family, is an essential virulence factor of S. suis capsular type 2 (SS2). Here, we found that morin hydrate (morin), a natural flavonoid that lacks anti-SS2 activity, inhibits the hemolytic activity of SLY, protects J774 cells from SS2-induced injury and protects mice from SS2 infection. Further, by molecular modeling and mutational analysis, we found that morin binds to the "stem" domain 2 in SLY and hinders its transformation from the monomer form to the oligomer form, which causes the loss of SLY activity. Our study demonstrates that morin hinders the cell lysis activity of SLY through a novel mechanism of interrupting the heptamer formation. These findings may lead to the development of promising therapeutic candidates for the treatment of SS2 infections.

Insights into structure and activity of natural compound inhibitors of pneumolysin.

Pneumolysin is the one of the major virulence factor of the bacterium Streptococcus pneumoniae. In previous report, it is shown that ß-sitosterol, a natural compound without antimicrobial activity, is a potent antagonist of pneumolysin. Here, two new pneumolysin natural compound inhibitors, with differential activity, were discovered via haemolysis assay. To explore the key factor of the conformation for the inhibition activity, the interactions between five natural compound inhibitors with differential activity and pneumolysin were reported using molecular modelling, the potential of mean force profiles. Interestingly, it is found that incorporation of the single bond (C22-C23-C24-C25) to replace the double bond (hydrocarbon sidechain) improved the anti-haemolytic activity. In view of the molecular modelling, binding of the five inhibitors to the conserved loop region (Val372, Leu460, and Tyr461) of the cholesterol binding sites led to stable complex systems, which was consistent with the result of ß-sitosterol. Owing to the single bond (C22-C23-C24-C25), campesterol and brassicasterol could form strong interactions with Val372 and show higher anti-haemolytic activity, which indicated that the single bond (C22-C23-C24-C25) in inhibitors was required for the anti-haemolytic activity. Overall, the current molecular modelling work provides a starting point for the development of rational design and higher activity pneumolysin inhibitors.

Inhibition of sortase A by chalcone prevents Listeria monocytogenes infection.

The critical role of sortase A in gram-positive bacterial pathogenicity makes this protein a good potential target for antimicrobial therapy. In this study, we report for the first time the crystal structure of Listeria monocytogenes sortase A and identify the active sites that mediate its transpeptidase activity. We also used a sortase A (SrtA) enzyme activity inhibition assay, simulation, and isothermal titration calorimetry analysis to discover that chalcone, an agent with little anti-L. monocytogenes activity, could significantly inhibit sortase A activity with an IC50 of 28.41 ± 5.34 µM by occupying the active site of SrtA. The addition of chalcone to a co-culture of L. monocytogenes and Caco-2 cells significantly inhibited bacterial entry into the cells and L. monocytogenes-mediated cytotoxicity. Additionally, chalcone treatment decreased the mortality of infected mice, the bacterial burden in target organs, and the pathological damage to L. monocytogenes-infected mice. In conclusion, these findings suggest that chalcone is a promising candidate for the development of treatment against L. monocytogenes infection.

Isorhamnetin Attenuates Staphylococcus aureus-Induced Lung Cell Injury by Inhibiting Alpha-Hemolysin Expression.

Staphylococcus aureus, like other gram-positive pathogens, has evolved a large repertoire of virulence factors as a powerful weapon to subvert the host immune system, among which alpha-hemolysin (Hla), a secreted pore-forming cytotoxin, plays a preeminent role. We observed a concentration-dependent reduction in Hla production by S. aureus in the presence of sub-inhibitory concentrations of isorhamnetin, a flavonoid from the fruits of Hippophae rhamnoides L., which has little antibacterial activity. We further evaluate the effect of isorhamnetin on the transcription of the Hla-encoding gene hla and RNAIII, an effector molecule in the agr system. Isorhamnetin significantly down-regulated RNAIII expression and subsequently inhibited hla transcription. In a co-culture of S. aureus and lung cells, topical isorhamnetin treatment protected against S. aureus-induced cell injury. Isorhamnetin may represent a leading compound for the development of anti-virulence drugs against S. aureus infections.

Verbascoside Alleviates Pneumococcal Pneumonia by Reducing Pneumolysin Oligomers.

Pneumolysin (PLY), an essential virulence factor of Streptococcus pneumoniae (pneumococcus), can penetrate the physical defenses of the host and possesses inflammatory properties. The vital role PLY plays in pneumococcus pathogenesis makes this virulence factor one of the most promising targets for the treatment of pneumococcal infection. Verbascoside (VBS) is an agent that does not exhibit bacteriostatic activity but has been shown to inhibit PLY-mediated cytotoxicity. The results from molecular dynamics simulations and mutational analysis indicated that VBS binds to the cleft between domains 3 and 4 of PLY, thereby blocking PLY's oligomerization and counteracting its hemolytic activity. Moreover, VBS can effectively alleviate PLY-mediated human alveolar epithelial (A549) cell injury, and treatment with VBS provides significant protection against lung damage and reduces mortality in a pneumococcal pneumonia murine model. Our results demonstrate that VBS is a strong candidate as a novel therapeutic in the treatment of Streptococcus pneumoniae infection.

ß-sitosterol interacts with pneumolysin to prevent Streptococcus pneumoniae infection.

Pneumolysin is one of the major virulence factors elaborated by Streptococcus pneumoniae; this toxin is a member of the cholesterol-dependent cytolysins. Engagement of cholesterol induces the formation of a multi-subunit complex by pneumolysin that lyses host cells by forming pores on the membrane. Because pneumolysin released by bacteria which have been killed by conventional antibiotics is still active, agents capable of directly attacking the toxin are considered advantageous against antimicrobials in the treatment of S. pneumoniae infections. Here we found that the phytosterol, ß-sitosterol, effectively protects against cell lysis caused by pneumolysin. This compound interacts with the toxin at Thr459 and Leu460, two sites important for being recognized by its natural ligand, cholesterol. Similar to cholesterol, ß-sitosterol induces pneumolysin oligomerization. This compound also protects cells from damage by other cholesterol-dependent toxins. Finally, this compound protects mice against S. pneumoniae infection. Thus, ß-sitosterol is a candidate for the development of anti-virulence agents against pathogens that rely on cholesterol-dependent toxins for successful infections.

Liquiritigenin prevents Staphylococcus aureus-mediated lung cell injury via inhibiting the production of α-hemolysin.

Staphylococcus aureus is a significant Gram-positive bacterium that is associated with a broad spectrum of diseases ranging from minor skin infections to lethal pneumonia, endocarditis, and toxinoses. α-Hemolysin is one of the most important exotoxins that contribute to the pathogenesis of S. aureus infections. Liquiritigenin is one of the most significant active components in licorice. In this study, hemolysis, western blot, and real-time reverse transcription-PCR assays were performed to investigate the impact of liquiritigenin on the production of S. aureus α-hemolysin. The results showed that low concentrations of liquiritigenin remarkably decreased S. aureus α-hemolysin production in a dose-dependent manner. Using live/dead cell staining and lactate dehydrogenase assays, we found that liquiritigenin could protect human lung cells (A549) from α-hemolysin-mediated injury. The data indicated that this compound could potentially be useful in developing drugs aiming at staphylococcal α-hemolysin.