OBJECTIVES:The global spread of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) involves evolutionary convergence. This study is to characterize the chromosomal integration of virulence plasmid fragments in a newly emerged CR-hvKP sequence type 2237 (ST2237) clone and to reconstruct its evolutionary history. METHODS:Seven clinical ST2237 isolates were collected from patients at Beijing Bo'ai Hospital, China, between November 2019 and June 2020. Isolates underwent short-read and nanopore long-read sequencing; complete genomes were assembled and annotated. All publicly available ST2237 genomes (n = 67) were incorporated for comparative, phylogenetic and Bayesian evolutionary analyses. RESULTS:The seven isolates were recovered from six patients in a single ward of Bo'ai Hospital, exhibited 1-17 pairwise single nucleotide polymorphisms and displayed a multidrug-resistant phenotype, indicating ongoing clonal dissemination. A ∼188 kb virulence plasmid fragment carrying iucABCD-iutA, rmpA2 and multiple resistance genes, flanked by IS26 elements, was chromosomally integrated in six of the seven isolates. Across Chinese ST2237 genomes, 95% harboured this integration, with minor rearrangements and occasional virulence gene deletions. The most recent common ancestor was dated to approximately 2012, with five major clades subsequently evolving and inter-provincial spreading across northern, central and western China. CONCLUSIONS:IS26-mediated chromosomal integration of large virulence-resistance modules represents a stable evolutionary strategy in this ST2237 CR-hvKP clone. The nosocomial cluster observed in the hospital and its dissemination to multiple provinces highlight the need for continuous nationwide genomic surveillance of this high-risk clone.

BACKGROUND:The rapid global spread of hypervirulence in Enterobacteriaceae, particularly in carbapenem-resistant Klebsiella pneumoniae, poses a significant public health threat. However, the key genetic vehicles and mechanisms driving horizontal transfer of hypervirulence-associated genes (iucA, iroB, rmpA, rmpA2, and peg-344) remain poorly defined, limiting effective surveillance. METHODS:We performed a large-scale genomic survey of 2,869 virulence-associated plasmid sequences and 2,337 complete Enterobacteriaceae chromosomes. Using comparative genomics and evolutionary analyses, we systematically identified and characterized Hypervirulence-associated Pseudo-Compound Transposons (Hva-PCTs), defined as structured mobile elements in which hypervirulence-associated genes are flanked by insertion sequences. RESULTS:Our results demonstrate that hypervirulence-associated genes are transmitted primarily as discrete IS-bounded units, which we term Hva-PCTs. We identified 29 distinct plasmid-borne Hva-PCTs (pHva-PCTs) and 30 chromosomal Hva-PCTs (cHva-PCTs). These modules show clear species-specific patterns: iucA/iroB-associated Hva-PCTs mainly originate in Escherichia coli and spread through IncFIB-containing multi-replicon plasmids (commonly combined with IncFIC(FII) and/or IncFII, while rmpA/rmpA2/peg-344-containing modules originate in K. pneumoniae and are disseminated via IncHI1B/repB plasmids. Three Hva-PCTs were detected on both plasmids and chromosomes (xHva-PCTs). In one clinical K. pneumoniae isolate (LS356), the identical composite module was present on both replicons. Simpler sub-modules, such as ISKqu3-rmpA2-iucA_1-IS102 and IS102-rmpA-peg-344-iroB_1-IS1A, frequently co-occur on the same plasmid; when positioned in tandem, they reconstitute the full composite structure. This assembly pattern is further supported by a partial duplication event in plasmid pP901. CD-HIT clustering (80% nucleotide identity and 90% coverage) showed that 13 of 22 major clusters contained both plasmid and chromosomal copies, with intra-cluster identities >80% across multiple sequence types and host species. CONCLUSION:Hypervirulence-associated genes in Enterobacteriaceae are disseminated mainly as IS-flanked Hva-PCTs rather than solely through intact virulence plasmids. These modules exhibit strong but not absolute host specificity. The presence of identical Hva-PCTs on plasmids and chromosomes suggests inter-replicon mobility, while their stepwise assembly from simpler sub-modules highlights modular accretion as a key evolutionary process. Tracking Hva-PCTs as distinct mobile units may complement existing plasmid- and gene-centric surveillance approaches for hypervirulent and convergent strains. Experimental validation of their transposition activity and phenotypic effects is still required.

PurposeST15 Klebsiella pneumoniae (Kp) is increasingly prevalent in China and worldwide. Currently, the mechanisms underlying the acquisition of hypervirulence-associated genes in sequence Type 15 (ST15) Kp are still not well studied. The global prevalence of ST15 Kp is increasing, alongside notable increases in both resistance and virulence.MethodsIn this study, we collected 766 isolates of Kp from a tertiary hospital and 19,060 Kp genomes from the NCBI Assembly database. We analyzed the phylogenetic characteristics and profiles of hypervirulence-associated genes among ST15 genomes, as well as their associations with other sequence types (STs).ResultsWe observed that the hypervirulence-associated genes in the ST15 carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates were all located on plasmids, indicating the potential for horizontal transfer. Plasmid exchange and recombination are closely linked to transmission patterns in different regions. Notably, in Asia, lineages carrying the virulence plasmid genes iucA and rmpA2 constitute the dominant population, accounting for 49.1% of the regional epidemic strains (with 48.5% lacking hypervirulence-associated genes). The clustering of these isolates and their close genetic relationships suggest that hypervirulent ST15 strains are well adapted and spread rapidly in this region. Two main pathways for the acquisition of virulence plasmids by ST15 CRKP isolates were identified: One involves the recombination of nonvirulence plasmids with the classic virulence plasmid pVir from ST11, and the other involves the direct acquisition of virulence plasmids from other genera. We also found that one ST15 CRKP strain harbors multiple copies of key virulence genes.ConclusionOverall, the genetic diversity of hypervirulence-associated genes within ST15 CRKP isolates may enhance the ability to survive and spread globally, offering crucial evidence for clinical strategies aimed at managing this strain.

Abstract The clinical management of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) is increasingly moving from reactive treatment to proactive early warning. However, existing environmental forecasting approaches remain constrained by heterogeneous exposure-response relationships, limited AECOPD-specific evidence for digital behavioral surveillance, and vulnerability to concept drift under nonstationary social and health care conditions. This viewpoint argues for a drift-aware multimodal early warning research agenda that integrates environmental exposure data, candidate digital behavioral signals, and routinely collected clinical burden indicators. Drawing on representative literature from environmental epidemiology, respiratory medicine, digital epidemiology, and medical informatics, we discuss current methodological challenges and potential directions for future AECOPD surveillance. Particular attention is paid to multimodal data integration, concept drift, adaptive state-space modeling, regime-aware handling of structural breaks, and equity-related challenges associated with digital behavioral data. Rather than presenting a validated forecasting system, we outline conceptual design considerations for future AECOPD-specific studies, including multimodal data fusion, state-space adaptive updating, drift subtype diagnosis, and subgroup-aware validation strategies. We also highlight important evidence gaps, particularly regarding the use of internet search queries and social media signals for AECOPD prediction. Drift-aware multimodal surveillance represents a promising direction for future AECOPD early warning, but substantial methodological, clinical, and implementation challenges remain. Future research should prioritize disease-specific validation, transparent evaluation of adaptive forecasting methods, and equitable deployment across populations with differing levels of digital access and health care resources.

AIMS:Interleukin-17A (IL-17A) aggravates poststroke neurological damage and enhances neutrophil extracellular traps (NETs) formation, yet the underlying mechanism remains unclear. This study aimed to elucidate how IL-17A regulates NETs generation after ischemic stroke. METHODS:Using a mouse middle cerebral artery occlusion (MCAO) model, we administered the Peptidylarginine deiminase 4 (PAD4) inhibitor GSK484 or an IL-17A-neutralizing antibody (IL-17mAb). Infarct volume and neurological function were assessed, and protein expression of PAD4, myeloperoxidase (MPO), citrullinated histones H3 (CitH3), protein kinase Cζ (PKCζ), and phosphorylated extracellular signal-regulated kinase (p-ERK) was evaluated. IL-17A-/- mice and primary neutrophils were used to further validate the signaling pathway. RESULTS:Inhibiting PAD4 with GSK484 can significantly reduce infarct size, improve neurological outcomes, and decrease PAD4, MPO, and CitH3 protein levels. Subsequently, we found that IL-17mAb treatment can reduce the expression of PAD4, MPO, and CitH3 in the peri-infarct area, as well as the expression of PKC-ζ and p-ERK. Similarly, the expression of PAD4 and CitH3 decreased in the peri-infarct area of IL-17A-/- MCAO mice. Finally, we verified IL-17A induced PAD4 upregulation via the PKCζ-ERK-ROS axis in vitro. CONCLUSION:IL-17A promotes NETs formation by upregulating PAD4 through the PKCζ-ERK-ROS pathway, exacerbating ischemic brain injury. Targeting this axis may offer a novel therapeutic strategy for stroke.

In sepsis, immunosuppression is commonly observed as lipopolysaccharide (LPS) tolerance in macrophages. Leukocyte immunoglobulin-like receptor B2 (LILRB2) is an inhibitory receptor on immune cells that may play a crucial role in the immunosuppressive phenotype of LPS-tolerant macrophages, although its exact function in sepsis remains unclear. In this study, macrophages were exposed to single or sequential LPS doses to induce LPS stimulation or tolerance. Cell viability was assessed using CCK-8 assay, apoptosis, and macrophage polarization were detected by flow cytometry, and pro-inflammatory cytokine levels were measured by RT-qPCR and ELISA. Molecular interactions were explored using Co-IP, ChIP, and dual-luciferase assays, while mRNA and protein expression were assessed by RT-qPCR and Western blotting. The results showed that LILRB2 was upregulated in macrophages following LPS stimulation, with a more significant increase in the LPS-tolerant group. Knocking down LILRB2 reversed the immunosuppressive phenotype of LPS-tolerant macrophages and restored the inhibition of MyD88/NF-κB signaling and p65 nuclear translocation caused by LPS tolerance. Mechanistically, LILRB2 interacted with Toll-like receptor 8 (TLR8) to inhibit the MyD88/NF-κB signaling pathway in LPS-tolerant macrophages. Furthermore, the upregulation of the Spi-1 proto-oncogene (SPI1) enhanced the immunosuppressive phenotype by transcriptionally activating LILRB2. In conclusion, SPI1 upregulation promoted the immunosuppressive phenotype of LPS-tolerant macrophages by activating LILRB2 transcription, which inhibited TLR8-mediated MyD88/NF-κB signaling. This study clarifies the role of LILRB2 and its underlying mechanisms in LPS-tolerant macrophages.

OBJECTIVES:To quantify the global and regional burden of bloodstream infections associated with and attributable to carbapenem-resistant Gram-negative bacteria. METHODS:We extracted data from the Measuring Infectious Causes and Resistance Outcomes for Burden Estimation database, which includes the estimated burden of 23 pathogens and 88 pathogen-drug combinations across 12 major infectious syndromes globally in 2019. The number and rate of deaths, as well as disability-adjusted life-years linked to bloodstream infections, were systematically analyzed. RESULTS:In 2019, bloodstream infections accounted for approximately 2.91 (95% UI, 1.74-4.53) million deaths globally, with Gram-negative bacteria responsible for 51.1% of these fatalities. An estimated 391,800 (95% UI 221,500-631,400) deaths were associated with carbapenem resistance, constituting 26.3% of all bloodstream infection-related deaths. The highest burden of carbapenem resistance was seen in South Asia, East Asia, and Eastern Europe, while the lowest burden was in Sub-Saharan Africa. Notably, Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa were the leading carbapenem-resistant pathogens contributing to mortality. CONCLUSIONS:Our findings underscore the significant global burden of bloodstream infections caused by carbapenem-resistant Gram-negative bacteria, with notable regional disparities. There is an urgent need for enhanced surveillance, improved infection prevention and control measures, and better access to first-line antibiotics, particularly in high-burden regions.

Human respiratory viruses (HRVs) can cause a spectrum of respiratory infections, which pose a significant challenge to global public health and are associated with a substantial economic impact. Traditional studies have often relied on in vitro culture systems utilizing transformed cell lines and animal models. However, there has been a shift towards emerging research models. Organoids are three-dimensional cell cultures that self-organize and differentiate into functional cell types, closely mimicking the structure and function of organs in vivo. Increasing evidence suggests that human lung organoids serve as reliable and effective models for studying HRVs. In this review, we compare common research models for HRVs, outline the establishment of human lung organoids, and explore their applications in HRV studies.

Background:Chronic obstructive pulmonary disease (COPD) and atrial fibrillation (AF) frequently coexist, and their concurrence is associated with worse clinical outcomes than either condition alone. Inflammation plays a central role in the pathogenesis of both diseases. The systemic immune-inflammation index (SII), derived from neutrophil, platelet, and lymphocyte counts, has emerged as a promising marker reflecting systemic inflammation. However, its prognostic value in critically ill patients with concurrent COPD and AF remains unclear. This study aimed to investigate the association between SII and in-hospital mortality in intensive care unit (ICU) patients with both COPD and AF. Methods:We identified ICU patients from Medical Information Mart for Intensive Care meeting the following criteria: patients with first ICU admission, concurrent diagnoses of COPD and AF; exclusion criteria included patients aged <18 years, patients without COPD, patients without AF, length of admission to ICU less than <24 hours, lymphocyte, neutrophil, or platelet counts missing or zero. Baseline patient characteristics included vital signs, laboratory profiles, medications, and critical illness severity scores. Baseline patient characteristics included vital signs, laboratory profiles, medications, and critical illness severity scores. The highest peripheral blood cell count recorded during the first 24 hours of ICU admission was used to calculate SII, and log transformation was applied. The study endpoint was in-hospital mortality, defined as death from any cause occurring during the hospitalization period. Logistic regression analysis, restricted cubic spline (RCS) regression, two-piecewise logistic regression modeling with smoothing, and subgroup analyses were performed to assess the relationship between SII and in-hospital mortality using data. Results:The cohort (mean age 74.1±9.4 years, 60.1% male) had an in-hospital mortality rate of 20.4%. After adjustment for sex, age, vital signs, medications, comorbidities, each unit increase in log transferred SII conferred an odds ratio (OR) of 1.72 [95% confidence interval (CI): 1.00-2.94, P=0.048]. The high log transferred SII group (≥2.9) showed 2.78-fold higher mortality (OR =2.78, 95% CI: 1.37-5.62, P=0.005) compared to the low log transferred SII group. RCSs demonstrated a nonlinear association between log transferred SII and in-hospital mortality (P for non-linearity =0.019). Subgroup analyses confirmed the robustness of this association. Conclusions:Our findings position SII as a potentially valuable biomarker for risk stratification in patients with COPD and AF, with the identified threshold potentially serving as a clinical decision point for intensifying monitoring or considering immunomodulatory therapies. Future prospective studies should validate these findings and explore whether SII guided management improves outcomes in this high-risk population.

Introduction:Tropheryma whipplei (TW) can cause various infections that are relatively rare worldwide. With the development of molecular biology, the ability to detect TW has increased in recent years. However, its significance in lower respiratory tract samples remains unclear. Patients and Methods:We collected the clinical data of 5 patients admitted to a tertiary care hospital in Beijing with TW detected by bronchoalveolar lavage fluid (BALF) mNGS and reviewed all case reports of TW-related pneumonia in China (up to November 2024) to analyse the features of this disease among Chinese patients. Results:A total of 41 articles reporting 55 cases were identified. Fifty-two (94.5%) patients had respiratory symptoms. Fifteen (27.3%) patients developed severe pneumonia. Confirmation of TW infection was achieved through methods including the assessment of TW reads and relative abundance (63.6%), empirical treatment (18.2%), lung biopsy histopathology (14.5%), and qPCR confirmation (3.6%). Fifty (90.9%) patients received antibiotic therapy. Fifty-one (92.7%) patients had a good prognosis. Conclusion:TW can enter the lower respiratory tract through multiple routes. When TW sequences are detected in lower respiratory tract samples, it is important to consider not only the read and relative abundance but also histopathological findings such as interstitial pneumonia and the presence of PAS- or PASM-positive bacilli within foamy macrophages as they can aid in diagnosing TW infection. MDT discussions and empirical antibiotic therapy targeting TW are viable options when a patient's condition deteriorates. Microbiological testing of saliva, gastric fluid, blood, and faeces may help clarify the source of TW.

Klebsiella pneumoniae, an emerging multidrug-resistant pathogen, exhibits hypermucoviscosity (HMV) as a critical virulence trait mediated by its capsular polysaccharide (CPS). Recent discoveries have determined acetylation as a significant modification for CPS, although its impact on HMV and virulence was previously unknown. This study elucidates the roles of two enzymes: Klebsiella pneumoniae Acetylated CPS Esterase (KpACE), an esterase that removes acetyl groups from CPS, and WcsU, an acetyltransferase that adds acetyl groups to CPS. KpACE is highly upregulated in an ompR-deficient mutant lacking HMV, and its overexpression consistently reduces HMV and diminishes virulence in a mouse model of pneumonia. The esterase domain-containing KpACE effectively deacetylates model sugar substrates and CPS-K2. Site-directed mutagenesis of the conserved catalytic histidine residue at position 370 significantly reduces its enzymatic activity. This reduction correlates with decreased HMV, affecting key virulence traits including biofilm formation and serum resistance. Similarly, a deficiency in the wcsU gene abolishes CPS acetylation, and reduces HMV and virulence. These results highlight the importance of the delicate balance between CPS acetylation by WcsU and deacetylation by KpACE in regulating the pathogenicity of K. pneumoniae. Understanding this balance provides new insights into the modulation of virulence traits and potential therapeutic targets for combating K. pneumoniae infections.

The human ether-a-go-go-related gene ( hERG ) encodes the Kv11.1 (or hERG) channel that conducts the rapidly activating delayed rectifier potassium current (IKr). Naturally occurring mutations in hERG impair the channel function and cause long QT syndrome type 2. Many missense hERG mutations lead to a lack of channel expression on the cell surface, representing a major mechanism for the loss-of-function of mutant channels. While it is generally thought that a trafficking defect underlies the lack of channel expression on the cell surface, in the present study, we demonstrate that the trafficking defective mutant hERG G601S can reach the plasma membrane but is unstable and quickly degrades, which is akin to WT hERG channels under low K+ conditions. We previously showed that serine (S) residue at 624 in the innermost position of the selectivity fi lter of hERG is involved in hERG membrane stability such that substitution of serine 624 with threonine (S624T) enhances hERG stability and renders hERG insensitive to low K+ culture. Here, we report that the intragenic addition of S624T substitution to trafficking defective hERG mutants G601S, N470D, and P596R led to a complete rescue of the function of these otherwise loss-of-function mutant channels to a level similar to the WT channel, representing the most effective rescue means for the function of mutant hERG channels. These fi ndings not only provide novel insights into hERG mutation-mediated channel dysfunction but also point to the critical role of S624 in hERG stability on the plasma membrane.

Introduction: Pulmonary histoplasmosis is a fungal disease that is endemic in North and Central America. It is relatively rare in China and commonly misdiagnosed as tuberculosis or cancer due to nonspecific clinical and radiographic manifestations. Rapid and accurate pathogen tests are critical for the diagnosis of pulmonary histoplasmosis. Methodology: We report two cases of pulmonary histoplasmosis. We collected all the relevant case reports on the Chinese mainland (from 1990 to 2022) to analyze features of this disease among Chinese patients. Results: A total of 42 articles reporting 101 cases were identified, and the two cases reported in this article were also included for analysis. Sixty-three (61.2%) patients had respiratory symptoms and 35 (34.0%) patients were asymptomatic. The most common radiographic findings were pulmonary nodules or masses (81.6%). Twenty-two (21.4%) patients were misdiagnosed as tuberculosis, and 37 (35.9%) were misdiagnosed as lung tumors before pathological findings. Metagenomic next‑generation sequencing (mNGS) testing provided a rapid diagnostic and therapeutic basis for three patients. Conclusions: Clinical features and imaging findings of pulmonary histoplasmosis are not specific. Relevant epidemiological history and timely pathogen detection are important for diagnosis. mNGS can shorten the time required for diagnosis and allow earlier initiation of targeted antibiotic therapy.

Klebsiella pneumoniae (K. pneumoniae), a significant contributor to the global challenge of antibiotic resistance, is not only a ubiquitous component of the human microbiome but also a potent pathogen capable of causing a spectrum of diseases. This review provides a thorough analysis of the intricate interactions between K. pneumoniae and the human immune system, elucidating its substantial impact on metabolic processes. We explore the mechanisms employed by K. pneumoniae to evade and manipulate immune responses, including molecular mimicry, immune modulation, and biofilm formation. The review further investigates the bacterium's influence on metabolic pathways, particularly glycolysis, highlighting how these interactions exacerbate disease severity. The emergence of multidrug-resistant and extremely drug-resistant strains within the Enterobacteriaceae family has heightened the public health crisis, underscoring the urgency for comprehensive research. We investigate the roles of the host's complement system, autophagy, cell death mechanisms, and various cytokines in combating K. pneumoniae infections, shedding light on areas that warrant further academic investigation. Additionally, the review discusses the challenges posed by K1- and K2-capsule polysaccharides in vaccine development due to their complex molecular structures and adhesive properties. Acknowledging the limited availability of effective antimicrobials, this review advocates for exploring alternative approaches such as immunotherapeutics, vaccinations, and phage therapy. We consolidate current knowledge on K. pneumoniae, covering classical and non-classical subtypes, antimicrobial resistance-mediated genes, virulence factors, and epidemiological trends in isolation and antibiotic resistance rates. This comprehensive review not only advances our understanding of K. pneumoniae but also underscores the imperative for ongoing research and collaborative efforts to develop new prevention and treatment strategies against this formidable pathogen.

Background:The pathogenesis of idiopathic pulmonary fibrosis (IPF) is not well understood. Given the known role of hepatitis C virus (HCV) in inducing cirrhosis, the virus has also received attention in the study of IPF. An earlier retrospective study found an increased incidence of IPF in patients with HCV, supported by evidence in the alveolar lavage fluid of the patients, whereas another set of observational studies did not find an association, which prompted us to explore a causal relationship. It is well known that HCV and hepatitis B virus (HBV) have some similarities: both are RNA viruses, and both have a strong ability to induce cirrhosis, which in turn leads to poor prognosis and increased mortality in patients with viral hepatitis. This factor also inspired us to start exploring whether there is a causal relationship between HBV and IPF. Due to the inherent limitations of previous studies, causality between chronic HBV/HCV infection and IPF is yet to be established. Mendelian randomization (MR) uses genetic variation as exposure and can be used to determine the causal effect of exposure on outcomes. Therefore, we used a two-sample MR study to determine if there is a causal relationship between viral hepatitis and IPF risk. Methods:Single nucleotide polymorphisms (SNPs) were used as instrumental variables (IVs), with chronic HBV and HCV infections as exposure factors and IPF as the outcome variable. Three methods, inverse variance weighting (IVW), weighted median (WM), and MR-Egger regression, were employed for the bidirectional MR. Sensitivity analyses, including horizontal pleiotropy analysis, Cochran's Q test, and leave-one-out evaluation of result reliability, were conducted. Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) and MR-Egger regression tests were used to monitor potential horizontal pleiotropic effects. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to interpret the causal relationship between chronic HBV and HCV infections and IPF. Finally, reverse MR analysis was performed to validate the robustness of the results. Results:The results of the IVW suggested that there was no causal relationship between chronic HBV infection (OR =1.039, 95% CI: 0.935-1.154, P=0.48) and chronic HCV infection (OR =1.146, 95% CI: 0.834-1.576, P=0.40) and the risk of IPF. Sensitivity analysis showed no evidence of reverse causation, horizontal pleiotropy, and heterogeneity. Conclusions:This study, using the bidirectional MR, provides preliminary evidence that chronic HBV and HCV infections are not causally related to IPF at the genetic level. However, this conclusion requires support from larger sample sizes in genome-wide association study (GWAS) databases for further MR analysis, and additional clinical studies and animal experiments are needed for validation.

Background Klebsiella pneumoniae (Kp) is a common community-acquired and nosocomial pathogen. Carbapenem-resistant and hypervirulent (CR-hvKp) variants can emerge rapidly within healthcare facilities and impacted by other infectious agents such as COVID-19 virus. Methods To understand the impact of COVID-19 virus on the prevalence of CR-hvKp, we accessed Kp genomes with corresponding metadata from GenBank. Sequence types (STs), antimicrobial resistance genes, and virulence genes, and those scores and CR-hvKp were identified. We analyzed population diversity and phylogenetic characteristics of five most common STs, measured the prevalence of CR-hvKp, identified CR-hvKp subtypes, and determined associations between carbapenem resistance gene subtypes with STs and plasmid types. These variables were compared pre- and during the COVID-19 pandemic. Findings The proportion of CR-hvKp isolates increased within multiple STs in different continents during the COVID-19 pandemic and persistent CR-hvKp subtypes were found in common STs. blaKPC was dominant in CG258, blaKPC-2 was detected in 97 % of the ST11 CR-hvKp, blaNDM subtypes were prominent in ST147 (87.4 %) and ST307 (70.8 %); blaOXA-48 and its subtypes were prevalent in ST15 (80.5 %). The possession of carbapenemase genes was different among subclades from different origins in different periods of time within each ST. IncFIB/IncHI1B hybrid plasmids contained virulence genes and carbapenemase genes and were predominant in ST147 (67.37 %) and ST307 (56.25 %). Interpretation The prevalence of CR-hvKp increased during the COVID-19 pandemic, which was evident by an increase in local endemic clones. This process was facilitated by the convergence of plasmids containing carbapenemase genes and virulence genes. These findings have implications for the appropriate use of antimicrobials and infection prevention and control during outbreaks of respiratory viruses and pandemic management.

The voltage-gated Kv1.5 potassium channel, conducting the ultra-rapid delayed rectifier K+ current (IKur) in human cells, plays important roles in the repolarization of atrial action potentials and regulation of the vascular tone. We previously reported that activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) induces endocytic degradation of cell-surface Kv1.5 channels, and a point mutation removing the phosphorylation site, T15A, in the N terminus of Kv1.5 abolished the PMA-effect. In the present study, using mutagenesis, patch clamp recording, Western blot analysis, and immunocytochemical staining, we demonstrate that ubiquitination is involved in the PMA-mediated degradation of mature Kv1.5 channels. Since the expression of the Kv1.4 channel is unaffected by PMA treatment, we swapped the N- and/or C-termini between Kv1.5 and Kv1.4. We found that the N-terminus alone did not but both N- and C-termini of Kv1.5 did confer PMA sensitivity to mature Kv1.4 channels, suggesting the involvement of Kv1.5 C-terminus in the channel ubiquitination. Removal of each of the potential ubiquitination residue Lysine at position 536, 565, and 591 by Arginine substitution (K536R, K565R, and K591R) had little effect, but removal of all three Lysine residues with Arginine substitution (3K-R) partially reduced PMA-mediated Kv1.5 degradation. Furthermore, removing the cysteine residue at position 604 by Serine substitution (C604S) drastically reduced PMA-induced channel degradation. Removal of the three Lysines and Cys604 with a quadruple mutation (3K-R/C604S) or a truncation mutation (Δ536) completely abolished the PKC activation-mediated degradation of Kv1.5 channels. These results provide mechanistic insight into PKC activation-mediated Kv1.5 degradation.

Abstract ID 95535Poster Board 267The human ether-a-go-go related gene (hERG) encodes the Kv11.1 channel which makes up the pore-forming subunit of the rapidly activating delayed rectifier potassium current (IKr). hERG has been implicated as a likely cause for the abnormally higher incidence of long QT syndrome (LQTS) observed in autoimmune patients. More recently, hERG has been identified to interact with the anti-Ro52 IgG autoantibody leading to endocytosis from the plasma membrane. The exact mechanism for this internalization is not well characterized, but one potential cause may be an immunoreceptor tyrosine-based inhibitory motif (ITIM) located within hERG’s C-terminus.Western blot analysis and whole-cell patch clamping were used in this study to analyze hERG expression and channel activity in hERG-HEK cells. hERG was found to interact with several antibodies to varying degrees, inducing a marked reduction in hERG expression from the surface of cells following culturing with IgG. The Fc domain of IgG in particular was identified to bind to the S5-pore linker of hERG, and not the antigen-binding Fab domain. In this study, we proved that the addition of a Src tyrosine kinase inhibitor (Src I1) significantly attenuated IgG-mediated hERG reduction, while adversely, vSrc overexpression mimicked this reduction of hERG. Here we demonstrate that the substitution of Y827 with an alanine (Y827A), thereby disabling hERG’s ITIM, renders hERG completely resistant to the effects of IgG and vSrc.Thus, our results indicate that not only does hERG interact with antibodies other than anti-Ro52 IgG, but that it behaves as a novel Fc receptor with a functioning ITIM that can mediate its own internalization. This is the first evidence of a mechanistic role for the ITIM found within hERG and provides clear insight into not only hERG’s role in autoimmune-induced LQTS but also its potential role in immunity.This work was supported by the Canadian Institutes of Health Research Grant [MOP 72911] to Shetuan Zhang.

目的 探索多重耐药肺炎克雷伯杆菌(MDR-KP)院内感染患者预后的影响因素,并构建预后预测的列线图模型.方法 收集北京市某三级医院2016年12月至2020年12月所有发生MDR-KP院内感染的病例168例,根据预后分为死亡组41例和生存组127例,使用Lasso回归分析得到关联强度较高的危险因素,将其纳入基于R语言的"rms"包进行分析并构建模型.结果 Lasso 回归分析显示,年龄≥80岁、抢救史、感染前30 d呼吸机使用史、感染前30 d输血史、感染前3个月手术史、感染前30 d胸腔穿刺史、感染部位位于肺部及下呼吸道为MDR-KP感染患者发生死亡的独立危险因素,分析得到相应的列线图预测模型.模型在训练集和测试集中ROC曲线下面积(AUC)分别为 0.834(95％CI:0.753～0.915)、0.744(95％CI:0.590～0.897).结论 根据模型评估数据及图表,该MDR-KP院内感染预后预测的列线图预测模型具有较好的检验效能及拟合优度,有助于临床早期识别不良预后患者,尽早采取相关临床干预措施.

Objective:To analyze the clinical characteristics of the patients with allergic asthma caused by pet allergens.Methods:This was a retrospective study.The clinical data of the adult outpatients with allergic asthma caused by pet allergens in Department of Pulmonary and Critical Care Medicine, Beijing Tsinghua Changgung Hospital, Tsinghua University from June 2019 to June 2022 were collected.The clinical characteristics, allergens, eosinophils (EOS) count and percentage, total IgE, FeNO, asthma control test (ACT) scores, pulmonary function, and the effects of allergen withdrawal on asthma control were analyzed retrospectively.Results:There were 575 cases of allergic asthma caused by pet allergens, accounting for 33.8% of allergic asthma (1 701 cases). Among them, 203 cases were allergic to pet allergens single, accounting for 11.9% of allergic asthma.A total of 372 cases were allergic to at least two kinds of inhalation allergens including pet allergens, accounting for 21.9% of allergic asthma.Among patients with asthma caused by pet allergens, the ratio of men to women is 1∶1.75, with an average age of (38.68±14.07) years.A total of 347 cases (60.3%) have a history of pet ownership, with higher pet ownership for mildly allergic patients.A total of 404 cases (70.3%) have chest tightness or wheezing.A total of 345 cases (60.0%) are allergic to allergens combined with dust mite.Compared to asthma patients caused by pet allergens single, patients with multiple inhalation allergens including pet allergens are associated with higher proportion of allergic rhinitis and other allergic diseases ( χ2=14.06, 23.58, both P<0.001), more patients with chest tightness or wheezing ( χ2=27.82, P<0.001), lower ACT scores ( t=5.06, P<0.001), higher blood EOS and total IgE ( Z=2.18, P=0.029; Z=8.89, P<0.001), more patients with obstructive ventilation dysfunction ( χ2=12.42, P=0.001), and lower FEV 1/predicted value% ( t=2.85, P=0.001). About asthma patients caused by pet allergens single, the blood EOS and EOS% in the severe allergic group were higher than those in the mild allergic group ( H=9.44, P<0.009; H=12.69, P=0.002), the total IgE in the severe allergic group was higher than those in the mild and moderate allergic groups ( H=28.68, P<0.001), and the FeNO value in the severe and moderate allergic groups was higher than that in the mild allergic group ( H=18.02, P<0.001). However, there was no significant difference in clinical symptoms and pulmonary function among the different allergic severity groups.With a follow-up of 3 months, the ACT score increased, blood EOS and FeNO decreased in the allergens withdrawal group compared to the allergens non-withdrawal group and the allergens contact free group (all P<0.001). Conclusions:Asthma patients caused by pet allergens account for 33.8% of allergic asthma cases.It is more common in young women, most of whom have pet ownership history.Patients with multiple inhalation allergens including pet allergens show more severe clinical symptoms, higher blood EOS and total IgE, and poorer lung function than those with pet allergens single.Patients severely allergic to pet allergens have higher serum EOS and total IgE, and more severe airway allergic reactions, but their clinical symptoms and pulmonary function are not related to allergy severity.Allergens withdrawal can increase ACT scores, decrease blood EOS, and improve eosinophilic airway inflammation more efficiently.