ELAVL1 promotes LPS-induced endothelial cells injury through modulation of cytokine storm.

Sepsis is a life-threatening systemic organ dysfunction caused by the host's unregulated response to a widespread bacterial infection. Endothelial injury is a major pathophysiologic symptom of sepsis and is considered a critical factor in promoting the progression of disease severity. ELAV like RNA binding protein 1(ELAVL1) is a ubiquitously expressed RNA-binding protein that may play an important role during sepsis. Nonetheless, the molecular mechanisms of ELAVL1 on endothelial cell damage in sepsis have not been well defined. Here, we aimed to confirm the role of ELAVL1 in sepsis-induced endothelial cell damage using lipopolysaccharide (LPS)-induced zebrafish and endothelial cells (ECs) models. We found that zebrafish larvae treated with LPS exhibited systemic endothelial cell damage, mostly manifested as pericardial edema, curved tail, and impaired angiogenesis. LPS treatments also significantly induced the expression levels of inflammatory cytokines (interleukin-6 (IL-6), IL-8, and tumor necrosis factor (TNF)-α) in vivo. In vitro, we observed the increase of ELAVL1 cytoplasmic translocation with LPS treatment. Mechanistically, targeted disruption of the ELAVL1 gene decreased the expression of TNF-α, IL-6, and IL-8 during induction of sepsis and alleviated LPS-induced blood vessel injury in zebrafish. Taken together, our study indicates that ELAVL1 knockdown may alleviate sepsis-induced endothelial cells injury by suppressing cytokine storm. Our research suggests that inhibition of ELAVL1 could reduce the level of inflammatory cytokine production induced by LPS and protect against endothelial cell injury. ELAVL1 might be a potential therapeutic target to block endothelial cells injury associated with sepsis.

SUPPLEMENTATION WITH NICOTINAMIDE RIBOSIDE ATTENUATES T CELL EXHAUSTION AND IMPROVES SURVIVAL IN SEPSIS.

ABSTRACT: T cell exhaustion is the main cause of sepsis-induced immunosuppression and is associated with the poor prognosis. Nicotinamide adenine dinucleotide (NAD + ) is well known for its anti-aging effect, but its role in sepsis-induced T cell exhaustion remains to be elucidated. In the present study, using a classic septic animal model, we found that the levels of NAD + and its downstream molecule, which is sirtuins 1 (SIRT1), in T cells in sepsis were decreased. Supplementation with nicotinamide ribose (NR), the precursor of NAD + , right after cecal ligation and puncture significantly increased the levels of NAD + and SIRT1. Supplementation with NR alleviated the depletion of mononuclear cells and T lymphocytes in spleen in sepsis and increased the levels of CD3 + CD4 + and CD3 + CD8 + T cells. Interestingly, both Th1 and Th2 cells were expanded after NR treatment, but the balance of Th1/Th2 was partly restored. Nicotinamide ribose also inhibited the regulatory T cells expansion and programmed cell death 1 expression in CD4 + T cells in sepsis. In addition, the bacteria load, organ damage (lung, heart, liver, and kidney), and the mortality of septic mice were reduced after NR supplementation. In summary, these results demonstrate the beneficial effect of NR on sepsis and T cell exhaustion, which is associated with NAD + /SIRT1 pathway.

A new criteria for acute on preexisting kidney dysfunction in critically ill patients.

Critically ill patients with preexisting kidney dysfunction (PKD) are at high risk for acute kidney injury (AKI). Nevertheless, there is no criteria for screening and classifying AKI in patients with PKD. In this study, after assessing relationship between the change in SCr from baseline and in-hospital mortality, a new criteria, named APKD, for identifying AKI in PKD was proposed. APKD defined AKI in critically ill patients with PKD as an absolute increase of ≥ 0.2 mg/dL in SCr within 48 h or an increase in SCr ≥ 1.1 times over baseline within 7 d. APKD detected more AKI among PKD patients compared with the other criteria. Additionally, the AKI patients identified by APKD but missed by the other criteria had higher mortality than those without AKI. APKD shows higher sensitivities than KDIGO criteria in predicating in-hospital mortality. APKD, but not the KDIGO, is effective for staging the severity of AKI in patients with PKD. In conclusion, APKD is more effective in screening and classifying AKI in critically ill patients with PKD compared with the earlier criteria, and it may helpful in guiding clinical treatment and predicting prognosis.

Characterization and identification of a novel chromosomal class C ß-lactamase, LAQ-1, and comparative genomic analysis of a multidrug resistance plasmid in Lelliottia amnigena P13.

Introduction: Lelliottia amnigena, a bacterium usually isolated from natural environments, may cause human infections and has been suggested to be naturally resistant to second- and third-generation cephalosporins. Methods: In this study, we determined the whole-genome sequence of an isolate, L. Amnigena P13, isolated from animal farm sewage. On the basis of genome sequence analysis, susceptibility testing, molecular cloning, and enzyme kinetic parameter analysis, we identified a novel chromosome-encoded AmpC ß-lactamase, LAQ-1. Results and Discussion: bla LAQ-1 is resistant to penicillin G, ampicillin, and several first- to fourth-generation cephalosporins, such as cefazolin, cefoxitin and cefepime. The MIC levels of some ß-lactams, such as cefoxitin, cefepime, aztreonam and cefazolin, for the recombinant clone (pUCP24-bla LAQ-1/DH5α) increased by approximately 4- to 64-fold compared with those of the control strain (pUCP24/DH5α). The kinetic properties of LAQ-1, with the highest catalytic activity observed toward piperacillin, were basically the same as those of typical class C ß-lactamases, and avibactam had a strong inhibitory effect on its hydrolytic activity. The genetic background of bla LAQ-1 was relatively conserved, and no mobile genetic element (MGE) was found around it. The plasmid pP13-67 of L. amnigena P13 harbored 12 resistance genes [qnrS1, aph(6)-Id, aadA2, sul1, sul2, bla TEM-1, qacEΔ1, dfrA12, tetA and floR] related to different mobile genetic elements within an ~22 kb multidrug resistance region. The multidrug resistance region shared the highest nucleotide sequence similarities with those of the chromosomes or plasmids of different bacterial species, indicating the possibility of horizontal transfer of these resistance genes among different bacterial species.

Whole-Genome Sequencing-Based Species Classification, Multilocus Sequence Typing, and Antimicrobial Resistance Mechanism Analysis of the Enterobacter cloacae Complex in Southern China.

Members of the Enterobacter cloacae complex (ECC) are important opportunistic nosocomial pathogens that are associated with a great variety of infections. Due to limited data on the genome-based classification of species and investigation of resistance mechanisms, in this work, we collected 172 clinical ECC isolates between 2019 and 2020 from three hospitals in Zhejiang, China and performed a retrospective whole-genome sequencing to analyze their population structure and drug resistance mechanisms. Of the 172 ECC isolates, 160 belonged to 9 classified species, and 12 belonged to unclassified species based on ANI analysis. Most isolates belonged to E. hormaechei (45.14%) followed by E. kobei (13.71%), which contained 126 STs, including 62 novel STs, as determined by multilocus sequence typing (MLST) analysis. Pan-genome analysis of the two ECC species showed that they have an "open" tendency, which indicated that their Pan-genome increased considerably with the addition of new genomes. A total of 80 resistance genes associated with 11 antimicrobial agent categories were identified in the genomes of all the isolates. The most prevailing resistance genes (12/29, 41.38%) were related to ß-lactams followed by aminoglycosides. A total of 247 ß-lactamase genes were identified, of which the blaACT genes were the most dominant (145/247, 58.70%), followed by the blaTEM genes (21/247, 8.50%). The inherent ACT type ß-lactamase genes differed among different species. blaACT-2 and blaACT-3 were only present in E. asburiae, while blaACT-9, blaACT-12, and blaACT-6 exclusively appeared in E. kobei, E. ludwigii, and E. mori. Among the six carbapenemase-encoding genes (blaNDM-1, blaNDM-5, blaIMP-1, blaIMP-4, blaIMP-26, and blaKPC-2) identified, two (blaNDM-1 and blaIMP-1) were identified in an ST78 E. hormaechei isolate. Comparative genomic analysis of the carbapenemase gene-related sequences was performed, and the corresponding genetic structure of these resistance genes was analyzed. Genome-wide molecular characterization of the ECC population and resistance mechanism would offer valuable insights into the effective management of ECC infection in clinical settings. IMPORTANCE The presence and emergence of multiple species/subspecies of ECC have led to diversity and complications at the taxonomic level, which impedes our further understanding of the epidemiology and clinical significance of species/subspecies of ECC. Accurate identification of ECC species is extremely important. Also, it is of great importance to study the carbapenem-resistant genes in ECC and to further understand the mechanism of horizontal transfer of the resistance genes by analyzing the surrounding environment around the genes. The occurrence of ECC carrying two MBL genes also indicates that the selection pressure of bacteria is further increased, suggesting that we need to pay special attention to the emergence of such bacteria in the clinic.