The effects of NDM-5 on Escherichia coli and the screening of interacting proteins.

Carbapenem-resistant Escherichia coli (E. coli) strains are widely distributed and spreading rapidly, creating significant challenges for clinical therapeutics. NDM-5, a novel mutant of New Delhi Metallo-ß-Lactamase-1 (NDM-1), exhibits high hydrolase activity toward carbapenems. Since the genetic backgrounds of clinically isolated carbapenem-resistant E. coli are heterogeneous, it is difficult to accurately evaluate the impact of blaNDM-5 on antibiotic resistance. Herein, E. coli BL21 was transformed with a plasmid harboring blaNDM-5, and the resultant strain was named BL21 (pET-28a-blaNDM-5). Consistent with the findings of previous studies, the introduction of exogenous blaNDM-5 resulted in markedly greater resistance of E. coli to multiple ß-lactam antibiotics. Compared with BL21 (pET-28a), BL21 (pET-28a-blaNDM-5) exhibited reduced motility but a significant increase in biofilm formation capacity. Furthermore, transcriptome sequencing was conducted to compare the transcriptional differences between BL21 (pET-28a) and BL21 (pET-28a-blaNDM-5). A total of 461 differentially expressed genes were identified, including those related to antibiotic resistance, such as genes associated with the active efflux system (yddA, mcbR and emrY), pili (csgC, csgF and fimD), biofilm formation (csgD, csgB and ecpR) and antioxidant processes (nuoG). Finally, the pGS21a plasmid harboring blaNDM-5 was transformed into E. coli Rosetta2, after which the expression of the NDM-5 protein was induced using isopropyl-ß-D-thiogalactoside (IPTG). Using glutathione-S-transferase (GST) pull-down assays, total proteins from E. coli were scanned to screen out 82 proteins that potentially interacted with NDM-5. Our findings provide new insight into the identified proteins to identify potential antibiotic targets and design novel inhibitors of carbapenem-resistant bacteria.

Inhibition of the P2X7 receptor prevents atrial proarrhythmic remodeling in experimental post-operative atrial fibrillation.

BACKGROUND: Post-operative atrial fibrillation (POAF) is a common complication in patients undergoing cardiac surgery. The purinergic receptor P2X7 (P2X7R) is involved in some cardiovascular diseases, whereas its effects on atrial fibrillation (AF) are unclear. OBJECTIVE: This study was to assess the effect of P2X7R on atrial arrhythmogenic remodeling in the rat model of sterile pericarditis (SP). METHODS: Male Sprague-Dawley (SD) rats were used to induce the SP model. Electrocardiogram, atrial electrophysiological protocol, histology, mRNA sequencing, real-time quantitative PCR, western blot, and Elisa assay were performed. RESULTS: SP significantly up-regulated P2X7R expression; increased AF susceptibility; reduced the protein expression of ion channels including Nav1.5, Cav1.2, Kv4.2, Kv4.3, and Kv1.5; caused atrial fibrosis; increased norepinephrine (NE) level in plasma; promoted the production of inflammatory cytokines such as TNF-α, IL-1ß, and IL-6; increased the accumulation of immune cells (CD68- and MPO- positive cells); and activated NLRP3 inflammasome signaling pathway. P2X7R antagonist Brilliant Blue G (BBG) mitigated SP-induced alterations. The mRNA sequencing demonstrated that BBG prevented POAF mainly by regulating the immune system. In addition, another selective P2X7R antagonist A740003, and IL-1R antagonist anakinra also reduced AF inducibility in the SP model. CONCLUSIONS: P2X7R inhibition prevents SP-induced atrial proarrhythmic remodeling, which is closely associated with the improvement of inflammatory changes, ion channel expression, atrial fibrosis, and sympathetic activation. The findings point to P2X7R inhibition as a promising target for AF (particularly POAF) and perhaps other conditions.

P2X7 receptor inhibition prevents atrial fibrillation in rodent models of depression.

AIMS: Depression, the most prevalent psychiatric disorder, is associated with the occurrence and development of atrial fibrillation (AF). P2X7 receptor (P2X7R) activation participates in the development of depression, but little attention has been given to its role in AF. This study was to investigate the effects of P2X7R on AF in depression models. METHODS AND RESULTS: Lipopolysaccharide (LPS) and chronic unpredictable stress (CUS) were carried out to induce depression in rodents. Behavioural assessments, atrial electrophysiological parameters, electrocardiogram (ECG) parameters, western blot, and histology were performed. Atrial fibrillation inducibility was increased in both LPS- and CUS-induced depression, along with the up-regulation of P2X7R in atria. CUS facilitated atrial fibrosis. CUS reduced heart rate variability (HRV) and increased the expression of TH and GAP43, representing autonomic dysfunction. Down-regulation of Nav1.5, Cav1.2, Kv1.5, Kv4.3, Cx40, and Cx43 in CUS indicated the abnormalities in ion channels. In addition, the expression levels of TLR4, P65, P-P65, NLRP3, ASC, caspase-1, and IL-1ß were elevated in depression models. Pharmacological inhibitor (Brilliant Blue G, BBG) or genetic deficiency of P2X7R significantly mitigated depressive-like behaviours; ameliorated electrophysiological deterioration and autonomic dysfunction; improved ion channel expression and atrial fibrosis; and prevented atrial NLRP3 inflammasome activation in the pathophysiological process of AF in depression models. CONCLUSION: LPS or CUS induces AF and promotes P2X7R-dependent activation of NLRP3 inflammasome, whereas pharmacological P2X7R inhibition or P2X7R genetic deficiency prevents atrial remodelling without interrupting normal atrial physiological functions. Our results point to P2X7R as an important factor in the pathology of AF in depression.

Tigecycline-resistance mechanisms and biological characteristics of drug-resistant Salmonella Typhimurium strains in vitro.

Increased drug resistance of Gram-negative bacteria to tetracycline caused by the unreasonable overuse of tigecycline has attracted extensive attention to reveal potential mechanisms. Here, we identified a tigecycline-resistant strain called TR16, derived from Salmonella Typhimurium ATCC13311 (AT), and examined its biological characteristics. Compared with AT, the TR16 strain showed significantly higher resistance to amoxicillin but lower resistance to gentamicin. Although the growth curves of TR16 and AT were similar, TR16 showed a significantly increased capacity for biofilm formation and a notably decreased motility compared to AT. Furthermore, transcriptome sequencing and reverse transcription-quantitative PCR (RT-qPCR) were implemented to evaluate the genetic difference between AT and TR16. Whole genome sequencing (WGS) analysis was also conducted to identify single nucleotide polymorphism (SNPs) and screened out two genetic mutations (lptD and rpsJ). The acrB gene of TR16 was knocked out through CRISPR/Cas9 system to further elucidate underlying mechanisms of tigecycline resistance in Salmonella Typhimurium. The up-regulation of acrB in TR16 was verified by RNA-seq and RT-qPCR, and the lack of acrB resulted in a 16-fold reduction in tigecycline resistance in TR16. Collectively, these results implied that AcrB efflux pump plays a key role in the tigecycline resistance of Salmonella, shedding light on the potential of AcrB efflux pump as a novel target for the discovery and development of new antibiotics.

TRPV2 inhibitor tranilast prevents atrial fibrillation in rat models of pulmonary hypertension.

Atrial fibrillation (AF) is common in pulmonary hypertension (PH), whereas the mechanisms and treatments remain to be explored. TRPV2 regulates the structure and function of the cardiovascular system; however, little attention has been given to its role in AF. This study was to determine whether TRPV2 was involved in PH-induced AF and the effects of TRPV2 inhibitor tranilast on AF in rat models of PH. Monocrotaline (MCT) and SU5416/hypoxia (SuHx)-induced PH models were performed to detect atrial electrophysiological parameters. Daily tranilast (a TRPV2 inhibitor) or saline was given starting 1 day before PH establishment. PH increased the susceptibility to AF, with TRPV2 up-regulated in the right atria. Compared to PH rats, tranilast reduced AF inducibility and the prolongations of ERP and APD; mitigated cardiopulmonary remodeling and the increases in P-wave duration and P-R interval; partially reversed the down-regulation of ion channels such as Cav1.2, Nav1.5, Kv4.3, Kv4.2, Kv1.5, Kir2.1, Kir3.1, Kir3.4 as well as connexin (Cx) 40 and Cx43; improved right atrial (RA) fibrosis, enlargement, and myocardial hypertrophy; decreased the accumulation of inflammatory cells; down-regulated inflammatory indicators such as TNF-α, IL-1ß, CXCL1, and CXCL2; and inhibited the activation of the PI3K-AKT-NF-κB signaling pathway. Our results reveal that TRPV2 participates in PH-induced AF, and TRPV2 inhibitor tranilast prevents PH-induced RA remodeling. TRPV2 might be a promising target for PH-induced AF.

Association between the TAPSE to PASP ratio and short-term outcome in patients with light-chain cardiac amyloidosis.

BACKGROUND: Amyloid light-chain cardiac amyloidosis (AL-CA) patients experiencing RV failure have a poorer prognosis. The echocardiographic ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary arterial systolic pressure (PASP) serves as a non-invasive proxy for evaluating the coupling between the right ventricle (RV) and pulmonary circulation. The aim of this study was to assess the association between the TAPSE/PASP ratio and short-term outcome in patients with AL-CA. METHODS: Seventy-one patients diagnosed with AL-CA were enrolled in this retrospective cohort study.Short-term outcome was defined as 6-month all-cause mortality. Receiver operating characteristic (ROC), logistic regression, and Kaplan-Meier analysis were used in this study. RESULTS: Among seventy-one patients with AL-CA (mean age, 62 ± 8 years, 69% male), 17 (24%) died within the first 6 months (mean follow-up period 55 ± 48 days). Linear regression analysis indicated that the TAPSE/PASP ratio was correlated with RV global longitudinal strain (r = -0.655, p < 0.001), RV free wall thickness (r = -0.599, p < 0.001), and left atrial reservoir strain (r = 0.770, p < 0.001). The time-dependent ROC and the area under the curve (AUC) showed that the TAPSE/PASP ratio was a better predictor (AUC = 0.798; 95% confidence interval (CI): 0.677-0.929) of short-term outcome than TAPSE (AUC = 0.734; 95% CI: 0.585-0.882) and PASP (AUC: 0.730; 95% CI: 0.587-0.874). Multivariate logistic regression showed that patients with the worse TAPSE/PASP (< 0.47 mm/mmHg) and lower systolic blood pressure (< 100 mmHg) had the highest risk of dying. CONCLUSIONS: The TAPSE/PASP ratio is associated with the short-term outcome of patients with AL-CA. The combination of TAPSE/PASP ratio < 0.474 mmHg and SBP < 100 mmHg could identify the subgroup of patients with AL-CA at elevated risk of poor prognosis.

Crystallization Kinetics Control Enabled by a Green Ionic Liquid Additive toward Efficient and Stable Carbon-Based Mesoscopic Perovskite Solar Cells.

Carbon-based mesoscopic perovskite solar cells (MPSCs) are becoming one of the most competitive photovoltaic technologies owing to their lower manufacturing cost and excellent stability. In this work, methylammonium acetate (MAAc), an ionic liquid additive, is added into methylammonium lead triiodide (MAPbI3) perovskite and is used to fabricate high-performance MPSCs. Systematic and detailed studies have shown that the MAAc interacts with PbI2 preferentially to form a MAPbI3-x(Ac)x intermediate phase that can effectively control the crystallization kinetics of MAPbI3 in the triple-mesoscopic layer. MAPbI3 films with an appropriate amount of MAAc exhibit higher crystallinity, lower defect density, and dense pore filling, which effectively reduce carrier non-radiative recombination loss in MPSCs. As a result, a champion power conversion efficiency (PCE) of 13.54% is obtained based on the optimized MAAc-engineered MPSCs. The PCE is 24% higher than 10.90% of the control devices. Moreover, unencapsulated MAAc-engineered MPSCs retain 90% of their initial PCE after being stored in the dark for 50 days under ambient atmosphere, which demonstrates much better air stability than control devices. This work provides an effective strategy for developing efficient and stable carbon-based MPSCs with an eco-friendly ionic liquid additive.