BACKGROUND:Macrophage polarization plays a key role in chronic inflammatory joint diseases such as rheumatoid arthritis.Cerium dioxide(CeO2)nanoparticles have a wide range of biomedical applications such as modulating the local inflammatory microenvironment of tissues.OBJECTIVE:To investigate the role of CeO2 nanoparticles on macrophage polarization and inflammatory factor expression,as well as inflammatory modulation in a co-culture system of macrophages and fibroblasts.METHODS:(1)CeO2 nanoparticles were dispersed and observed morphologically by transmission electron microscopy.(2)Human leukemia monocytes(THP-1)were induced to differentiate and establish the M1 macrophage pro-inflammatory cell model of rheumatoid arthritis.The cells were divided into M0 group(undifferentiated macrophages),M1 group(successful macrophage modeling),CeO2 nanoparticle treatment group(M1 group with CeO2 nanoparticle treatment),and dexamethasone control group(M1 group with dexamethasone treatment)and incubated for 48 hours.The effects of CeO2 nanoparticles on the expression of inflammatory factors(endogenous nitric oxide synthase,CD86,CD80)in M1 macrophages and M1 macrophage phenotype(CD80,CD206)were detected by RT-qPCR,western blot assay,and flow cytometry.(3)A co-culture system of macrophages and fibroblasts was established,and CeO2 nanoparticles acted on the upper macrophages.The regulation of CeO2 nanoparticles on the expression of inflammatory factors(interleukin-6,tumor necrosis factor-α,cyclooxygenase-2,and endogenous nitric oxide synthase)of fibroblasts in the co-culture system was observed at the mRNA and protein levels.RESULTS AND CONCLUSION:(1)Transmission electron microscopy showed that the diameter of CeO2 nanoparticles was(19.5±2.0)nm.(2)Compared with the M0 group,the mRNA of endogenous nitric oxide synthase and CD86,and the protein expression of endogenous nitric oxide synthase and CD80 in the M1 group were upregulated.Compared with the M1 group,the mRNA expression of endogenous nitric oxide synthase and CD86,and the protein expression of endogenous nitric oxide synthase and CD80 in the CeO2 nanoparticle treatment group were downregulated.Flow cytometry showed that 20 nm CeO2 nanoparticles downregulated the number of M1 macrophages.(3)Compared with the M1 group,20 nm CeO2 nanoparticles downregulated the mRNA and protein expression of inflammatory factors(tumor necrosis factor α,interleukin 6,cyclooxygenase 2,and endogenous nitric oxide synthase)in the co-culture system HFL1 cells.(4)The results showed that 20 nm CeO2 nanoparticles can alleviate inflammation in the co-culture system by inhibiting the expression of pro-inflammatory factors in M1 macrophages,providing a new idea for the treatment of inflammatory diseases such as rheumatoid arthritis.

BACKGROUND:Macrophage polarization plays a key role in chronic inflammatory joint diseases such as rheumatoid arthritis.Cerium dioxide(CeO2)nanoparticles have a wide range of biomedical applications such as modulating the local inflammatory microenvironment of tissues.OBJECTIVE:To investigate the role of CeO2 nanoparticles on macrophage polarization and inflammatory factor expression,as well as inflammatory modulation in a co-culture system of macrophages and fibroblasts.METHODS:(1)CeO2 nanoparticles were dispersed and observed morphologically by transmission electron microscopy.(2)Human leukemia monocytes(THP-1)were induced to differentiate and establish the M1 macrophage pro-inflammatory cell model of rheumatoid arthritis.The cells were divided into M0 group(undifferentiated macrophages),M1 group(successful macrophage modeling),CeO2 nanoparticle treatment group(M1 group with CeO2 nanoparticle treatment),and dexamethasone control group(M1 group with dexamethasone treatment)and incubated for 48 hours.The effects of CeO2 nanoparticles on the expression of inflammatory factors(endogenous nitric oxide synthase,CD86,CD80)in M1 macrophages and M1 macrophage phenotype(CD80,CD206)were detected by RT-qPCR,western blot assay,and flow cytometry.(3)A co-culture system of macrophages and fibroblasts was established,and CeO2 nanoparticles acted on the upper macrophages.The regulation of CeO2 nanoparticles on the expression of inflammatory factors(interleukin-6,tumor necrosis factor-α,cyclooxygenase-2,and endogenous nitric oxide synthase)of fibroblasts in the co-culture system was observed at the mRNA and protein levels.RESULTS AND CONCLUSION:(1)Transmission electron microscopy showed that the diameter of CeO2 nanoparticles was(19.5±2.0)nm.(2)Compared with the M0 group,the mRNA of endogenous nitric oxide synthase and CD86,and the protein expression of endogenous nitric oxide synthase and CD80 in the M1 group were upregulated.Compared with the M1 group,the mRNA expression of endogenous nitric oxide synthase and CD86,and the protein expression of endogenous nitric oxide synthase and CD80 in the CeO2 nanoparticle treatment group were downregulated.Flow cytometry showed that 20 nm CeO2 nanoparticles downregulated the number of M1 macrophages.(3)Compared with the M1 group,20 nm CeO2 nanoparticles downregulated the mRNA and protein expression of inflammatory factors(tumor necrosis factor α,interleukin 6,cyclooxygenase 2,and endogenous nitric oxide synthase)in the co-culture system HFL1 cells.(4)The results showed that 20 nm CeO2 nanoparticles can alleviate inflammation in the co-culture system by inhibiting the expression of pro-inflammatory factors in M1 macrophages,providing a new idea for the treatment of inflammatory diseases such as rheumatoid arthritis.

OBJECTIVE To investigate the effect and potential mechanism of toosendanin in enhancing the antileukemic activity of cytosine arabinoside against acute myeloid leukemia （AML） based on the mammalian target of rapamycin complex 1 （mTORC1） signaling pathway.METHODS Female NSG immunodeficient mice were used to establish an AML model via a single γ-ray irradiation followed by a single tail-vein injection of a U937 cell suspension. The effects of cytosine arabinoside （2.5 mg/kg）， toosendanin （1.0 mg/kg）， and cytosine arabinoside+toosendanin （2.5 mg/kg+1.0 mg/kg） on body weight， survival time， peripheral blood routine indicators， histopathological morphology， and the expressions of autophagy-related proteins were explored. Using U937 cells as the subject， the effects of cytosine arabinoside （1 μmol/L）， toosendanin （160 nmol/L）， and cytosine arabinoside+toosendanin （1 μmol/L+160 nmol/L） on the expressions of autophagy-related proteins， mTORC1 signaling pathway-related proteins and mRNAs were investigated. The targeting relationship between toosendanin and the selective autophagy ligand 1 （also known as p62） was validated， and the Gene Ontology （GO） and Kyoto Encyclopedia of Genes and Genomes （KEGG） enrichment analyses， as well as molecular docking， were performed. A p62 -knockdown U937 stable cell line was constructed， and the underlying mechanism of toosendanin-induced sensitization was verified.RESULTS Animal experiments confirmed that the combination of toosendanin and cytosine arabinoside significantly improved body weight， survival time and peripheral blood routine indicators in AML mice （ P ＜0.05）， alleviated pathological changes such as leukemic cell infiltration and focal necrosis in bone marrow， liver， and spleen tissues， and modulated the expressions of autophagy-related proteins. Cell experiments confirmed that toosendanin could reverse cytosine arabinoside-induced activation of the autophagy cascade （manifested by downregulation of the protein expressions of microtubule-associated protein 1 light chain 3B and Beclin-1， upregulation the protein expression of p62）， and might inhibit the expression of the downstream Unc-51-like autophagy activating kinase 1 （ULK1） complex （including ULK1， ULK2， autophagy-related protein 13， and FAK family interacting protein of 200 kDa） by activating the mTORC1 signaling pathway （ P ＜0.05）. The sensitizing effect of toosendanin was associated with the inhibition of autophagy and the regulation of the mTORC1 signaling pathway； it could stably bind to p62 via hydrophobic interactions. Mechanism verification experiments indicated that upon p62 knockdown， toosendanin was no longer able to activate the mTORC1 signaling pathway or inhibit autophagy.CONCLUSIONS Toosendanin may enhance chemo-sensitivity of AML cells to cytosine arabinoside by directly targeting the p62 protein， which subsequently activates the mTORC1 signaling pathway， and thereby suppresses cytosine arabinoside-induced protective autophagy.

Objective To examine the changing prevalence and antimicrobial resistance profiles of Burkholderia cepacia in 52 hospitals across China from 2015 to 2021.Methods A total of 9 261 strains of B.cepacia were collected from 52 hospitals between January 1,2015 and December 31,2021.Antimicrobial susceptibility of the strains was tested using Kirby-Bauer method or automated antimicrobial susceptibility testing systems according to a unified protocol.The results were interpreted according to the breakpoints released in the Clinical & Laboratory Standards Institute(CLSI)guidelines(2023 edition).Results A total of 9 261 strains of B.cepacia were isolated from all age groups,especially elderly patients.The proportion was 11.1％(1 032 strains)in children,significantly lower than the proportion in adults.About half(46.5％,4 310/9 261)of the strains were isolated from patients at least 60 years old and 42.3％(3 919/9 261)of the strains were isolated from young adults.Most isolates(71.1％)were isolated from sputum and respiratory secretions,followed by urine(10.7％)and blood samples(8.1％).B.cepacia isolates were highly susceptible to the five antimicrobial agents recommended in the CLSI M100 document(33rd edition,2023).B.cepacia isolates showed relatively higher resistance rates to meropenem and levofloxacin.However,the resistance rates to ceftazidime,trimethoprim-sulfamethoxazole,and minocycline remained below 8.1％.The percentage of B.cepacia strains resistant to levofloxacin was the highest compared to other antibiotics in any of the three age groups(from 12.4％in the patients＜18 years old to 20.6％in the patients aged 60 years or older).Conclusions B.cepacia is one of the clinically important non-fermenting gram-negative bacteria.Accurate and timely reporting of antimicrobial susceptibility test results and ongoing antimicrobial resistance surveillance are helpful for rational prescription of antimicrobial agents and proper prevention and control of nosocomial infections.

Objective To summarize the changing prevalence of carbapenem resistance in Enterobacterales based on the data of CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021 for improving antimicrobial treatment in clinical practice.Methods Antimicrobial susceptibility testing was performed using a commercial automated susceptibility testing system according to the unified CHINET protocol.The results were interpreted according to the breakpoints of the Clinical & Laboratory Standards Institute(CLSI)M100 31st ed in 2021.Results Over the seven-year period(2015-2021),the overall prevalence of carbapenem-resistant Enterobacterales(CRE)was 9.43％(62 342/661 235).The prevalence of CRE strains in Klebsiella pneumoniae,Citrobacter freundii,and Enterobacter cloacae was 22.38％,9.73％,and 8.47％,respectively.The prevalence of CRE strains in Escherichia coli was 1.99％.A few CRE strains were also identified in Salmonella and Shigella.The CRE strains were mainly isolated from respiratory specimens(44.23±2.80)％,followed by blood(20.88±3.40)％and urine(18.40±3.45)％.Intensive care units(ICUs)were the major source of the CRE strains(27.43±5.20)％.CRE strains were resistant to all the β-lactam antibiotics tested and most non-β-lactam antimicrobial agents.The CRE strains were relatively susceptible to tigecycline and polymyxins with low resistance rates.Conclusions The prevalence of CRE strains was increasing from 2015 to 2021.CRE strains were highly resistant to most of the antibacterial drugs used in clinical practice.Clinicians should prescribe antimicrobial agents rationally.Hospitals should strengthen antibiotic stewardship in key clinical settings such as ICUs,and take effective infection control measures to curb CRE outbreak and epidemic in hospitals.

Objective To characterize the changing species distribution and antibiotic resistance profiles of respiratory isolates in hospitals participating in the CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021.Methods Commercial automated antimicrobial susceptibility testing systems and disk diffusion method were used to test the susceptibility of respiratory bacterial isolates to antimicrobial agents following the standardized technical protocol established by the CHINET program.Results A total of 589 746 respiratory isolates were collected from 2015 to 2021.Overall,82.6％of the isolates were Gram-negative bacteria and 17.4％were Gram-positive bacteria.The bacterial isolates from outpatients and inpatients accounted for(6.0±0.9)％and(94.0±0.1)％,respectively.The top microorganisms were Klebsiella spp.,Acinetobacter spp.,Pseudomonas aeruginosa,Staphylococcus aureus,Haemophilus spp.,Stenotrophomonas maltophilia,Escherichia coli,and Streptococcus pneumoniae.Each microorganism was isolated from significantly more males than from females(P＜0.05).The overall prevalence of methicillin-resistant S.aureus(MRSA)was 39.9％.The prevalence of penicillin-resistant S.pneumoniae was 1.4％.The prevalence of extended-spectrum β-lactamase(ESBL)-producing E.coli and K.pneumoniae was 67.8％and 41.3％,respectively.The overall prevalence of carbapenem-resistant E.coli,K.pneumoniae,Enterobacter cloacae,Pseudomonas aeruginosa,and Acinetobacter baumannii was 3.7％,20.8％,9.4％,29.8％,and 73.3％,respectively.The prevalence of β-lactamase was 96.1％in Moraxella catarrhalis and 60.0％in Haemophilus influenzae.The H.influenzae isolates from children(＜18 years)showed significantly higher resistance rates to β-lactam antibiotics than the isolates from adults(P＜0.05).Conclusions Gram-negative bacteria are still predominant in respiratory isolates associated with serious antibiotic resistance.Antimicrobial resistance surveillance should be strengthened in clinical practice to support accurate etiological diagnosis and appropriate antimicrobial therapy based on antimicrobial susceptibility testing results.

Objective:To translate the quality of life tool for patients with aplastic anaemia and paroxysmal nocturnal haemoglobinuria (QLQ-AA/PNH) into Chinese, and to test its reliability and validity.Methods:According to the scale translation principle, the Chinese version of QLQ-AA/PNH was formed through translation, back translation and cross-cultural adaptation. A cross-sectional survey method was used to conveniently select 58 patients with aplastic anemia who were treated in the hematology department of the Second Affiliated Hospital of Dalian Medical University from January 2018 to September 2023 for investigation, and to evaluate the reliability and validity of the scale.Results:The Chinese version of QLQ-AA/PNH retains 36 items, and 5 common factors (psychological status dimension, life burden dimension, physical condition dimension, illness anxiety dimension and other symptom dimension) were extracted through exploratory factor analysis. The cumulative variance contribution rate reached 71.33%, and the factor load of each entry was greater than 0.5 on corresponding common factors. The Cronbach α coefficient of the scale as a whole was 0.971, the broken half reliability coefficient was 0.985, the Cronbach α coefficient of each common factor was 0.637 to 0.954, and the broken half reliability coefficient was 0.637 to 0.930. Conclusions:The Chinese version of QLQ-AA/PNH has been proved to be valid and reliable. It is a valuable tool for evaluating the quality of life among patients with aplastic anaemia.

Aim To investigate the effect of PU.1 in-hibitor DB2313 on lupus nephritis in MRL/lpr mice and its mechanism.Methods Thirty female MRL/lpr mice were randomly divided into the model group,DB2313 group and TACI-Ig group,with 10 mice in each group.Another 10 female BALB/c mice were se-lected as normal control groups.Mice in the DB2313 group received intraperitoneal DB2313 injections every two days,and those in the TACI-Ig group received subcutaneous injections of TACI-Ig every two days.Mice in the control group and model group were intra-gastrically given the same amount of 0.9％NaCl injec-tion every day.Before the drug intervention and for 1 to 5 weeks after the intervention,the urine of mice was collected regularly,the urine protein content was meas-ured,and the renal damage index was evaluated.The histopathological changes of kidney were observed by HE,Masson and PAS staining.The expression levels of immune complex of C3 in kidney tissue were detec-ted by immunohistochemistry.The concentrations of u-rea nitrogen(BUN),serum creatinine(Scr),inter-leukin-6(IL-6),and tumor necrosis factor alpha(TNF-α)in the serum samples were assayed utilizing the respective kits.The expression levels of PU.1 and FLT3 in kidney tissues were determined by immunoflu-orescence technology,and the protein expressions of PU.1,FLT3,PI3K,AKT and phosphorylated AKT(p-AKT)in kidney tissues were detected by Western blot.Results DB2313 treatment significantly allevia-ted the pathological damage of kidney in MRL/lpr mice,and reduced the deposition of C3,kidney injury index and 24-hour urine protein in renal tissue.The results of ELISA showed that DB2313 administration could significantly reduce the serum levels of BUN,Scr,IL-6 and TNF-α in MRL/lpr mice.The results of immunofluorescence and Western blot further showed that DB2313 treatment could significantly down-regu-late the protein expression of PU.1,PI3K and p-AKT,and up-regulate the protein expression of FLT3.Con-clusion DB2313 has an ameliorating effect on lupus nephritis in MRL/lpr mice,and its underlying mecha-nism may involve the inhibition of the transcription fac-tor PU.1-mediated signaling pathway.

Aim To construct and analyze the genotype of G protein-coupled receptor kinase 2(GRK2)conditional knockout mice in synoviocytes,and to provide an animal model for stud-ying the function of GRK2 in synoviocytes.Methods Grk2flox/+mice were bred to generate Grk2flox/flox mice,Grk2flox/flox mice were bred to Col1a1-iCre+mice,Grk2flox/+Col1a1-iCre+mice were bred to Grk2flox/flox mice.Grk2flox/flox Col1a1-iCre+mice were ob-tained as target mice.DNA was extracted and amplified by PCR to identify the genotype.Western blot was used to verify the effect of Grk2 knockout in synovium,liver and kidney tissues.HE staining was used to detect the effects of Grk2 conditional knockout in synovial cells on ankle synovium,liver and kidney tissues.Multiple immunofluorescence was used to detect GRK2 expression in synovial cells.Results The results of gene iden-tification showed that Grk2flox/flox Col1a1-iCre+mice had both Flox and Col1a1-iCre genotypes.Western blot results showed that GRK2 expression decreased in synovial tissues of Grk2flox/flox Col1a1-iCre+mice,but there was no significant change in the expression of GRK2 in liver and kidney tissues.HE staining showed that Grk2flox/flox Col1a1-iCre+mice had no significant pathological changes in the ankle synovium,liver and kidney.The results of multiple immunofluorescence showed that GRK2 expression in synovial cells of Grk2flox/flox Col1a1-iCre+mice de-creased.Conclusion Grk2 conditional knockout mice in syno-viocytes are successfully constructed and identified,which pro-vides an animal model for further study of the role of GRK2 in synovial-related diseases.

Objective To investigate the distribution and antimicrobial resistance profiles of common pathogens isolated from cerebrospinal fluid(CSF)in CHINET program from 2015 to 2021.Methods The bacterial strains isolated from CSF were identified in accordance with clinical microbiology practice standards.Antimicrobial susceptibility test was conducted using Kirby-Bauer method and automated systems per the unified CHINET protocol.Results A total of 14 014 bacterial strains were isolated from CSF samples from 2015 to 2021,including the strains isolated from inpatients(95.3％)and from outpatient and emergency care patients(4.7％).Overall,19.6％of the isolates were from children and 80.4％were from adults.Gram-positive and Gram-negative bacteria accounted for 68.0％and 32.0％,respectively.Coagulase negative Staphylococcus accounted for 73.0％of the total Gram-positive bacterial isolates.The prevalence of MRSA was 38.2％in children and 45.6％in adults.The prevalence of MRCNS was 67.6％in adults and 69.5％in children.A small number of vancomycin-resistant Enterococcus faecium(2.2％)and linezolid-resistant Enterococcus faecalis(3.1％)were isolated from adult patients.The resistance rates of Escherichia coli and Klebsiella pneumoniae to ceftriaxone were 52.2％and 76.4％in children,70.5％and 63.5％in adults.The prevalence of carbapenem-resistant E.coli and K.pneumoniae(CRKP)was 1.3％and 47.7％in children,6.4％and 47.9％in adults.The prevalence of carbapenem-resistant Acinetobacter baumannii(CRAB)and Pseudomonas aeruginosa(CRPA)was 74.0％and 37.1％in children,81.7％and 39.9％in adults.Conclusions The data derived from antimicrobial resistance surveillance are crucial for clinicians to make evidence-based decisions regarding antibiotic therapy.Attention should be paid to the Gram-negative bacteria,especially CRKP and CRAB in central nervous system(CNS)infections.Ongoing antimicrobial resistance surveillance is helpful for optimizing antibiotic use in CNS infections.