Caffeic acid modulates activation of neutrophils and attenuates sepsis-induced organ injury by inhibiting 5-LOX/LTB4 pathway.

BACKGROUND: Sepsis is a critical systemic inflammatory syndrome which usually leads to multiple organ dysfunction. Caffeic acid (CA), a phenolic compound derived from various plants, has been proved to be essential in neuroprotection, but its role in septic organ damage is unclear. This research aimed to investigate whether CA protects against organ injury in a mouse model of cecal ligation and puncture (CLP). METHODS: CA (30 mg/kg) or vehicle was administered by intraperitoneal injection immediately after CLP. The samples of blood, lungs, and livers were collected 24 h later. Organ injury was assessed by histopathological examination (HE staining), neutrophil infiltration (myeloperoxidase fluorescence), oxidative stress levels (MDA, SOD, HO-1), and inflammatory cytokines (TNF-α, IL-1ß, and IL-6) release in lung and liver tissues. Neutrophil extracellular trap (NET) formation was analyzed by immunofluorescence. In vitro experiments were performed to investigate the potential mechanisms of CA using small interfering RNA (siRNA) techniques in neutrophils, and the effect of CA on neutrophil apoptosis was analyzed by flow cytometry. RESULTS: Results showed that CA treatment improved the 7-day survival rate and attenuated the histopathological injury in the lung and liver of CLP mice. CA significantly reduced neutrophil infiltration in the lungs and livers of CLP mice. TNF-α, IL-1ß, IL-6 and LTB4 were reduced in serum, lung, and liver of CA-treated CLP mice, and phosphorylation of MAPK (p38, ERK, JNK) and p65 NF-κB was inhibited in lungs and livers. CA treatment further increased HO-1 levels and enhanced superoxide dismutase (SOD) activity, but reduced malondialdehyde (MDA) levels and NET formation. Similarly, in vitro experiments showed that CA treatment and 5-LOX siRNA interference inhibited inflammatory activation and NET release in neutrophils, suppressed MAPK and NF-κB phosphorylation in LPS-treated neutrophils, and decreased LTB4 and cfDNA levels. Flow cytometric analysis revealed that CA treatment reversed LPS-mediated delayed apoptosis in human neutrophils, and Western blot also indicated that CA treatment inhibited Bcl-2 expression but increased Bax expression. CA treatment did not induce further changes in neutrophil apoptosis, inflammatory activation, and NET release when 5-LOX was knocked down by siRNA interference. CONCLUSIONS: CA has a protective effect on lung and liver injury in a murine model of sepsis, which may be related to inhibition of the 5-LOX/LTB4 pathway.

ß-Nicotinamide mononucleotide activates NAD+/SIRT1 pathway and attenuates inflammatory and oxidative responses in the hippocampus regions of septic mice.

Sepsis-associated encephalopathy (SAE) is one of the common serious complications in sepsis, and the pathogenesis of SAE remains unclear. Sirtuin 1 (SIRT1) has been reported to be downregulated in the hippocampus and SIRT1 agonists can attenuated the cognitive dysfunction in septic mice. Nicotinamide adenine dinucleotide (NAD+) is a key substrate to maintain the deacetylation activity of SIRT1. As an intermediate of NAD+, ß-Nicotinamide Mononucleotide (NMN) has been reported to be promising in treating neurodegenerative diseases and cerebral ischemic injury. Thus we sought to investigate the potential role of NMN in SAE treatment. The SAE model was established by cecal ligation and puncture (CLP) in vivo, and neuroinflammation model was established with LPS-treated BV-2 cells in vitro. Memory impairment was assessed by Morris water maze and fear conditioning tests. As a result, the levels of NAD+, SIRT1 and PGC-1α were significantly reduced in the hippocampus of septic mice, while the acetylation of total lysine, phosphorylation of P38 and P65 were enhanced. All these changes induced by sepsis were inverted by NMN. Treating with NMN resulted in improved behavior performance in the fear conditioning tests and Morris water maze. Apoptosis, inflammatory and oxidative responses in the hippocampus of septic mice were attenuated significantly after NMN administration. These protective effect of NMN against memory dysfunction, inflammatory and oxidative injuries were reversed by the SIRT1 inhibitor, EX-527. Similarly, LPS-induced activation of BV-2 cells were attenuated by NMN, EX-527 or SIRT1 knockdown could reverse such effect of NMN in vitro. In conclusion, NMN is protective against sepsis-induced memory dysfunction, and the inflammatory and oxidative injuries in the hippocampus region of septic mice. The NAD+/SIRT1 pathway might be involved in one of the mechanisms of the protective effect.

PD-L1 promotes GSDMD-mediated NET release by maintaining the transcriptional activity of Stat3 in sepsis-associated encephalopathy.

Sepsis-associated encephalopathy (SAE), as shown as acute and long-term cognitive impairment, is associated with increased mortality of sepsis. The causative factors of SAE are diverse and the underlying pathological mechanisms of SAE remain to be fully elucidated. Multiple studies have demonstrated a crucial role of microglia in the development of SAE, but the role of neutrophils and neutrophil extracellular traps (NETs) in SAE is still unclear. Here, we firstly show that in murine sepsis model, neutrophils and NETs promote blood-brain barrier (BBB) disruption, neuronal apoptosis and microglia activation in hippocampus and induce hippocampus-dependent memory impairment. Anti-Gr-1 antibody or DNase I treatment attenuates these sepsis-induced changes. Then, we find that genetic deletion of neutrophil GSDMD or PD-L1 reduces NET release and improves SAE in murine sepsis model. Finally, in human septic neutrophils, p-Y705-Stat3 binds to PD-L1, promotes PD-L1 nuclear translocation and enhances transcription of the gasdermin D (GSDMD) gene. In summary, our findings firstly identify a novel function of PD-L1 in maintaining transcriptional activity of p-Y705-Stat3 to promote GSDMD-dependent NET release in septic neutrophils, which plays a critical role in the development of SAE.

The role of G protein-coupled receptor in neutrophil dysfunction during sepsis-induced acute respiratory distress syndrome.

Sepsis is defined as a life-threatening dysfunction due to a dysregulated host response to infection. It is a common and complex syndrome and is the leading cause of death in intensive care units. The lungs are most vulnerable to the challenge of sepsis, and the incidence of respiratory dysfunction has been reported to be up to 70%, in which neutrophils play a major role. Neutrophils are the first line of defense against infection, and they are regarded as the most responsive cells in sepsis. Normally, neutrophils recognize chemokines including the bacterial product N-formyl-methionyl-leucyl-phenylalanine (fMLP), complement 5a (C5a), and lipid molecules Leukotriene B4 (LTB4) and C-X-C motif chemokine ligand 8 (CXCL8), and enter the site of infection through mobilization, rolling, adhesion, migration, and chemotaxis. However, numerous studies have confirmed that despite the high levels of chemokines in septic patients and mice at the site of infection, the neutrophils cannot migrate to the proper target location, but instead they accumulate in the lungs, releasing histones, DNA, and proteases that mediate tissue damage and induce acute respiratory distress syndrome (ARDS). This is closely related to impaired neutrophil migration in sepsis, but the mechanism involved is still unclear. Many studies have shown that chemokine receptor dysregulation is an important cause of impaired neutrophil migration, and the vast majority of these chemokine receptors belong to the G protein-coupled receptors (GPCRs). In this review, we summarize the signaling pathways by which neutrophil GPCR regulates chemotaxis and the mechanisms by which abnormal GPCR function in sepsis leads to impaired neutrophil chemotaxis, which can further cause ARDS. Several potential targets for intervention are proposed to improve neutrophil chemotaxis, and we hope that this review may provide insights for clinical practitioners.

GSDMD-mediated NETosis promotes the development of acute respiratory distress syndrome.

Gasdermin D (GSDMD) is a classical molecule involved in pyroptosis. It has been reported to be cleaved into N-terminal fragments to form pores in the neutrophil membrane and promote the release of neutrophil extracellular traps (NETs). However, it remains unclear if GSDMD is involved in neutrophil regulation and NET release during ARDS. The role of neutrophil GSDMD in the development of ARDS was investigated in a murine model of ARDS induced by lipopolysaccharide (LPS) using the neutrophil specific GSDMD-deficient mice. The neutrophil GSDMD cleavage and its relationship with NETosis were also explored in ARDS patients. The cleavage of GSDMD in neutrophils from ARDS patients and mice was upregulated. Inhibition of GSDMD by genetic knockout or inhibitors resulted in reduced production of NET both in vivo and in vitro, and attenuation of LPS-induced lung injury. Moreover, in vitro experiments showed that the inhibition of GSDMD attenuated endothelial injury co-cultured with neutrophils from ARDS patients, while extrinsic NETs reversed the protective effect of GSDMD inhibition. Collectively, our data suggest that the neutrophil GSDMD cleavage is crucial in NET release during ARDS. The NET release maintained by cleaved GSDMD in neutrophils may be a key event in the development of ARDS.

Nicotinamide Mononucleotide Attenuates LPS-Induced Acute Lung Injury With Anti-Inflammatory, Anti-Oxidative and Anti-Apoptotic Effects.

INTRODUCTION: Nicotinamide mononucleotide (NMN) is a nucleotide that is commonly recognized for its role as an intermediate of nicotinamide adenine dinucleotide (NAD+) biosynthesis with multiple pharmacological effects. The purpose of this study was to evaluate the protective effect of nicotinamide mononucleotide (NMN) against lipopolysaccharide (LPS)-induced acute lung injury (ALI). METHODS: We investigated the effect of NMN on ALI-induced inflammatory response, oxidative stress, and cell apoptosis. The ALI mouse model was performed by injecting LPS intratracheally at a dose of 10 mg/kg in 50 µL saline. Flow cytometry was used to detect neutrophil infiltration in bronchoalveolar lavage fluid (BALF), and ELISA was used to detect the contents of inflammatory cytokines TNF-α, IL-1ß and IL-6 in BALF. Oxidative stress was evaluated by determining the superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in lung tissue. ROS formation was analyzed by immunofluorescence. Western blotting was performed to detect apoptotic levels and p38MAPK/NF-κB phosphorylation levels in lung tissue. RESULTS: In the ALI mouse model, NMN showed a significant therapeutic effect compared to the LPS group. NMN attenuated the pathological damage and cell apoptosis in lung tissue, decreased the levels of TNF-α, IL-1ß, and IL-6 in BALF, and reduced the number of total cells and neutrophils in BALF. In addition, NMN attenuated the LPS-induced elevation of dry-to-wet ratio, MDA content, p38 MAPK and p65 NF-κB phosphorylation levels, and the SOD activity was increased by NMN treatment. CONCLUSIONS: In conclusion, the present study showed that NMN exerted a protective effect on LPS-induced ALI with anti-inflammatory, antioxidative, and antiapoptotic effects.

The implication of targeting PD-1:PD-L1 pathway in treating sepsis through immunostimulatory and anti-inflammatory pathways.

Sepsis currently remains a major contributor to mortality in the intensive care unit (ICU), with 48.9 million cases reported globally and a mortality rate of 22.5% in 2017, accounting for almost 20% of all-cause mortality worldwide. This highlights the urgent need to improve the understanding and treatment of this condition. Sepsis is now recognized as a dysregulation of the host immune response to infection, characterized by an excessive inflammatory response and immune paralysis. This dysregulation leads to secondary infections, multiple organ dysfunction syndrome (MODS), and ultimately death. PD-L1, a co-inhibitory molecule expressed in immune cells, has emerged as a critical factor in sepsis. Numerous studies have found a significant association between the expression of PD-1/PD-L1 and sepsis, with a particular focus on PD-L1 expressed on neutrophils recently. This review explores the role of PD-1/PD-L1 in immunostimulatory and anti-inflammatory pathways, illustrates the intricate link between PD-1/PD-L1 and sepsis, and summarizes current therapeutic approaches against PD-1/PD-L1 in the treatment and prognosis of sepsis in preclinical and clinical studies.

Corrigendum: PD-L1 maintains neutrophil extracellular traps release by inhibiting neutrophil autophagy in endotoxin-induced lung injury.

[This corrects the article DOI: 10.3389/fimmu.2022.949217.].

Dysregulation of neutrophil death in sepsis.

Sepsis is a prevalent disease that has alarmingly high mortality rates and, for several survivors, long-term morbidity. The modern definition of sepsis is an aberrant host response to infection followed by a life-threatening organ dysfunction. Sepsis has a complicated pathophysiology and involves multiple immune and non-immune mediators. It is now believed that in the initial stages of sepsis, excessive immune system activation and cascading inflammation are usually accompanied by immunosuppression. During the pathophysiology of severe sepsis, neutrophils are crucial. Recent researches have demonstrated a clear link between the process of neutrophil cell death and the emergence of organ dysfunction in sepsis. During sepsis, spontaneous apoptosis of neutrophils is inhibited and neutrophils may undergo some other types of cell death. In this review, we describe various types of neutrophil cell death, including necrosis, apoptosis, necroptosis, pyroptosis, NETosis, and autophagy, to reveal their known effects in the development and progression of sepsis. However, the exact role and mechanisms of neutrophil cell death in sepsis have not been fully elucidated, and this remains a major challenge for future neutrophil research. We hope that this review will provide hints for researches regarding neutrophil cell death in sepsis and provide insights for clinical practitioners.

Salvianolic Acid A Protects against Lipopolysaccharide-Induced Acute Lung Injury by Inhibiting Neutrophil NETosis.

Salvianolic acid A (SAA) is one of bioactive polyphenol extracted from a Salvia miltiorrhiza (Danshen), which was widely used to treat cardiovascular disease in traditional Chinese medicine. SAA has been reported to be protective in cardiovascular disease and ischemia injury, with anti-inflammatory and antioxidative effect, but its role in acute lung injury (ALI) is still unknown. In this study, we sought to investigate the therapeutic effects of SAA in a murine model of lipopolysaccharide- (LPS-) induced ALI. The optimal dose of SAA was determined by comparing the attenuation of lung injury score after administration of SAA at three different doses (low, 5 mg/kg; medium, 10 mg/kg; and, high 15 mg/kg). Dexamethasone (DEX) was used as a positive control for SAA. Here, we showed that the therapeutic effect of SAA (10 mg/kg) against LPS-induced pathologic injury in the lungs was comparable to DEX. SAA and DEX attenuated the increased W/D ratio and the protein level, counts of total cells and neutrophils, and cytokine levels in the BALF of ALI mice similarly. The oxidative stress was also relieved by SAA and DEX according to the superoxide dismutase and malondialdehyde. NET level in the lungs was elevated in the injured lung while SAA and DEX reduced it significantly. LPS induced phosphorylation of Src, Raf, MEK, and ERK in the lungs, which was inhibited by SAA and DEX. NET level and phosphorylation level of Src/Raf/MEK/ERK pathway in the neutrophils from acute respiratory distress syndrome (ARDS) patients were also inhibited by SAA and DEX in vitro, but the YEEI peptide reversed the protective effect of SAA completely. The inhibition of NET release by SAA was also reversed by YEEI peptide in LPS-challenged neutrophils from healthy volunteers. Our data demonstrated that SAA ameliorated ALI via attenuating inflammation, oxidative stress, and neutrophil NETosis. The mechanism of such protective effect might involve the inhibition of Src activation.

PD-L1 maintains neutrophil extracellular traps release by inhibiting neutrophil autophagy in endotoxin-induced lung injury.

Programmed death ligand 1 (PD-L1) is not only an important molecule in mediating tumor immune escape, but also regulates inflammation development. Here we showed that PD-L1 was upregulated on neutrophils in lipopolysaccharide (LPS)-induced acute respiratory distress syndrome (ARDS). Neutrophil specific knockout of PD-L1 reduced lung injury in ARDS model induced by intratracheal LPS injection. The level of NET release was reduced and autophagy is elevated by PD-L1 knockout in ARDS neutrophils both in vivo and in vitro. Inhibition of autophagy could reverse the inhibitory effect of PD-L1 knockout on NET release. PD-L1 interacted with p85 subunit of PI3K at the endoplasmic reticulum (ER) in neutrophils from ARDS patients, activating the PI3K/Akt/mTOR pathway. An extrinsic neutralizing antibody against PD-L1 showed a protective effect against ARDS. Together, PD-L1 maintains the release of NETs by regulating autophagy through the PI3K/Akt/mTOR pathway in ARDS. Anti-PD-L1 therapy may be a promising measure in treating ARDS.

Comparative genome anatomy reveals evolutionary insights into a unique amphitriploid fish.

Triploids are rare in nature because of difficulties in meiotic and gametogenic processes, especially in vertebrates. The Carassius complex of cyprinid teleosts contains sexual tetraploid crucian carp/goldfish (C. auratus) and unisexual hexaploid gibel carp/Prussian carp (C. gibelio) lineages, providing a valuable model for studying the evolution and maintenance mechanism of unisexual polyploids in vertebrates. Here we sequence the genomes of the two species and assemble their haplotypes, which contain two subgenomes (A and B), to the chromosome level. Sequencing coverage analysis reveals that C. gibelio is an amphitriploid (AAABBB) with two triploid sets of chromosomes; each set is derived from a different ancestor. Resequencing data from different strains of C. gibelio show that unisexual reproduction has been maintained for over 0.82 million years. Comparative genomics show intensive expansion and alterations of meiotic cell cycle-related genes and an oocyte-specific histone variant. Cytological assays indicate that C. gibelio produces unreduced oocytes by an alternative ameiotic pathway; however, sporadic homologous recombination and a high rate of gene conversion also exist in C. gibelio. These genomic changes might have facilitated purging deleterious mutations and maintaining genome stability in this unisexual amphitriploid fish. Overall, the current results provide novel insights into the evolutionary mechanisms of the reproductive success in unisexual polyploid vertebrates.

Senkyunolide I protect against lung injury via inhibiting formation of neutrophil extracellular trap in a murine model of cecal ligation and puncture.

BACKGROUND: Senkyunolide I (SEI), a component of a Chinese herb named Ligusticum Chuanxiong hort, which is included in the formulation of Xuebijing Injection, a medication used to treat sepsis in China. Our previous study showed that SEI was protective against sepsis-associated encephalopathy and the present study was performed to investigate the role of SEI in sepsis-induced lung injury in a murine model of cecal ligation and puncture (CLP). METHODS: SEI (36 mg/kg in 200 µl) or vehicle was administered immediately after CLP surgery. The lung injury was assessed 24 h later by histopathological tests, protein concentration in the bronchoalveolar lavage fluid (BALF), neutrophil recruitment in the lung tissue (myeloperoxidase fluorescence, MPO), pro-inflammatory cytokines and oxidative responses. Platelet activation was detected by CD42d/GP5 immunofluorescence and neutrophil extracellular trap (NET) were determined by immunofluorescence assays and enzyme linked immunosorbent assay (ELISA) of MPO-DNA. In vitro experiments were performed to detect the level of MPO-DNA complex released by SEI-treated neutrophils stimulated with phorbol 12-myristate 13-acetate (PMA) or co-cultured with platelets from CLP mice. RESULTS: SEI administration relieved the injury degree in CLP mice according to the histopathological tests (P < 0.05 compared with DMSO + CLP group). Protein level in the BALF and neutrophil infiltration were remarkably reduced by SEI after CLP surgery (P < 0.05 compared with DMSO + CLP group). TNF-α, IL-1ß and IL-6 were decreased in the plasma and lung tissues from CLP mice treated with SEI (P < 0.05 compared with DMSO + CLP group). The phosphorylation of JNK, ERK, p38 and p65 were all inhibited by SEI (P < 0.05 compared with DMSO + CLP group). Immunofluorescence of MPO showed that neutrophil number was significantly lower in SEI treated CLP mice than in vehicle treated CLP mice (P < 0.05). The CD42d/GP5 staining suggested that platelet activation was significantly reduced and the NET level in the lung tissue and plasma was greatly attenuated by SEI treatment (P < 0.05 compared with DMSO + CLP group). In vitro experiments showed that the MPO-DNA level stimulated by PMA was significantly reduced by SEI treatment (P < 0.05 compared with DMSO treatment). Co-culture neutrophils with platelets from CLP mice resulted in higher level of MPO-DNA complex, while SEI partly reversed such effects of platelet on NET formation. CONCLUSIONS: SEI was protective against lung injury induced by CLP in mice. The NET formation was significantly reduced by SEI treatment, which might be involved in the mechanism of the protective effect.

Mechanism of Mitophagy and Its Role in Sepsis Induced Organ Dysfunction: A Review.

Autophagy, an evolutionarily conserved process, plays an important role in maintaining cellular homeostasis under physiological and pathophysiological conditions. It is widely believed that mitochondria influence the development of disease by regulating cellular metabolism. When challenged by different stimuli, mitochondria may experience morphological disorders and functional abnormalities, leading to a selective form of autophagy-mitophagy, which can clear damaged mitochondria to promote mitochondrial quality control. Sepsis is a complex global problem with multiple organ dysfunction, often accompanied by manifold mitochondrial damage. Recent studies have shown that autophagy can regulate both innate and acquired immune processes to protect against organ dysfunction in sepsis. Sepsis-induced mitochondrial dysfunction may play a pathophysiological role in the initiation and progression of sepsis-induced organ failure. Mitophagy is reported to be beneficial for sepsis by eliminating disabled mitochondria and maintaining homeostasis to protect against organ failure. In this review, we summarize the recent findings and mechanisms of mitophagy and its involvement in septic organ dysfunction as a potential therapeutic target.

Dexmedetomidine reduces the incidence of postoperative delirium after cardiac surgery: a meta-analysis of randomized controlled trials.

BACKGROUND: The role of dexmedetomidine in preventing postoperative delirium (POD) after cardiac surgery remains controversial because of several recent trials with negative results. We aimed to perform an updated meta-analysis of randomized controlled trials (RCTs) to clarify this controversy. METHODS: RCTs investigating the perioperative administration of dexmedetomidine in cardiac surgery were retrieved from PubMed, Web of Science, and the Cochrane library until August,27,2020. Two researchers independently screened the literature, collected the data and evaluated the bias risk of the included studies. The meta-analysis was performed with the RevMan 5.3. RESULTS: A total of 15 studies including 2813 patients were included in the study. A pooled result showed that dexmedetomidine could reduce the risk of POD in adult population underwent cardiac surgery (OR 0.56, 95%CI 0.36-0.89, P = 0.0004, I2 = 64%). The subgroup analysis demonstrated that the protective effect of dexmedetomidine was only present in the patients injected with dexmedetomidine after surgery but not from the start of surgery, in the adult patients without specific age limitation but not in the elderly, and in the studies in comparison with other sedatives but not with placebo. There were no statistical differences when analyzing the secondary outcomes including hypotension (OR 1.13; 95% CI 0.54-2.37, P < 0.00001, I2 = 85%), bradycardia (OR 1.72; 95% CI 0.84-3.53, P = 0.04, I2 = 58%) and atrial fibrillation (OR 0.87; 95% CI 0.70-1.08, P = 0.43, I2 = 0). CONCLUSIONS: Dexmedetomidine can reduce the incidence of POD compared to other sedatives and opioids after cardiac surgery in adult patients. The proper population and timing for perioperative use of dexmedetomidine after cardiac surgery remain to be further investigated.

Senkyunolide I Protects against Sepsis-Associated Encephalopathy by Attenuating Sleep Deprivation in a Murine Model of Cecal Ligation and Puncture.

Sepsis may lead to sleep deprivation, which will promote the development of neuroinflammation and mediate the progression of sepsis-associated encephalopathy (SAE). Senkyunolide I, an active component derived from an herb medicine, has been shown to provide a sedative effect to improve sleep. However, its role in sepsis is unclear. The present study was performed to investigate whether Senkyunolide I protected against SAE in a murine model of cecal ligation and puncture (CLP). Here, we showed that Senkyunolide I treatment improved the 7-day survival rate and reduced the excessive release of cytokines including TNF-α, IL-6, and IL-1ß. A fear conditioning test was performed, and the results showed that Senkyunolide I attenuated CLP-induced cognitive dysfunction. Senkyunolide I treatment also decreased the phosphorylation levels of inflammatory signaling proteins, including p-ERK, p-JNK, p-P38, and p-P65, and the level of inflammatory cytokines, including TNF-α, IL-6, and IL-1ß, in the hippocampus homogenate. Sleep deprivation was attenuated by Senkyunolide I administration, as demonstrated by the modification of the BDNF and c-FOS expression. When sleep deprivation was induced manually, the protective effect of Senkyunolide I against inflammatory responses and cognitive dysfunction was reversed. Our data demonstrated that Senkyunolide I could protect against sepsis-associated encephalopathy in a murine model of sepsis via relieving sleep deprivation.

A Stable Quaternized Chitosan-Black Phosphorus Nanocomposite for Synergetic Disinfection of Antibiotic-Resistant Pathogens.

Antibiotics are widely used for treatment of bacterial infections, and their overuse has contributed to microbial resistance. Currently, an alternative antibiotic-free therapy for inactivating bacteria is of great interest. Black phosphorus (BP), a biocompatible and nontoxic rising-star two-dimensional layered material, has gained remarkable interest in many bioapplications including biosensing, cancer therapy, drug delivery, and also antibacterial treatment. However, BP nanosheets suffer from instability in ambient environments due to rapid oxidation and degradation. To address this issue, BP nanosheets were modified with quaternized chitosan (QCS) by electrostatic adsorption to prepare a BP-QCS composite for photothermal/pharmaco treatment of bacterial infection. The BP-QCS has obviously enhanced solubility and chemical stability in aqueous suspensions. We have demonstrated that under near-infrared (NIR) irradiation, the BP-QCS can synergistically inactivate more than 95% methicillin-resistant Staphylococcus aureus (S. aureus) (MRSA) and Escherichia coli within 10 min with a dose of only 75 µg/mL in vitro. Meanwhile, the BP-QCS composite under NIR can synergistically inactivate 98% S. aureus in vivo. Furthermore, the BP-QCS suspensions at effective antibacterial concentrations have negligible cytotoxicity and in vivo toxicity.

MeLAD: an integrated resource for metalloenzyme-ligand associations.

MOTIVATION: Metalloenzymes are attractive targets for therapeutic intervention owing to their central roles in various biological processes and pathological situations. The fast-growing body of structural data on metalloenzyme-ligand interactions is facilitating efficient drug discovery targeting metalloenzymes. However, there remains a shortage of specific databases that can provide centralized, interconnected information exclusive to metalloenzyme-ligand associations. RESULTS: We created a Metalloenzyme-Ligand Association Database (MeLAD), which is designed to provide curated structural data and information exclusive to metalloenzyme-ligand interactions, and more uniquely, present expanded associations that are represented by metal-binding pharmacophores (MBPs), metalloenzyme structural similarity (MeSIM) and ligand chemical similarity (LigSIM). MeLAD currently contains 6086 structurally resolved interactions of 1416 metalloenzymes with 3564 ligands, of which classical metal-binding, non-classical metal-binding, non-metal-binding and metal water-bridging interactions account for 63.0%, 2.3%, 34.4% and 0.3%, respectively. A total of 263 monodentate, 191 bidentate and 15 tridentate MBP chemotypes were included in MeLAD, which are linked to different active site metal ions and coordination modes. 3726 and 52 740 deductive metalloenzyme-ligand associations by MeSIM and LigSIM analyses, respectively, were included in MeLAD. An online server is provided for users to conduct metalloenzyme profiling prediction for small molecules of interest. MeLAD is searchable by multiple criteria, e.g. metalloenzyme name, ligand identifier, functional class, bioinorganic class, metal ion and metal-containing cofactor, which will serve as a valuable, integrative data source to foster metalloenzyme related research, particularly involved in drug discovery targeting metalloenzymes. AVAILABILITY AND IMPLEMENTATION: MeLAD is accessible at https://melad.ddtmlab.org. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Dual-modal aptasensor for the detection of isocarbophos in vegetables.

An aptamer-based colorimetric-phosphorescent assay was developed for the detection of isocarbophos. The colorimetric assay relied on the aggregation of gold nanoparticles (AuNPs) caused by the competitive binding of aptamer between isocarbophos and AuNPs in the presence of a high salt concentration. The further addition of persistent luminescence nanorods (PLNRs) into the system showed the phosphorescence sensitively proportional to the concentration of isocarbophos, due to the inner filter effect between PLNRs and AuNPs. The assay showed good linearity within 50-500 µg/L and 5-160 µg/L, and limit of detection of 7.1 µg/L and 0.54 µg/L in colorimetry and phosphorescence mode, respectively. The feasibility of this approach for food analysis was demonstrated with the sensitive and selective determination of isocarbophos residues in vegetables.