Integration of metagenomics and metaproteomics in the intestinal lavage fluids benefits construction of discriminative model and discovery of biomarkers for HBV liver diseases.

Intestinal lavage fluid (IVF) containing the mucosa-associated microbiota instead of fecal samples was used to study the gut microbiota using different omics approaches. Focusing on the 63 IVF samples collected from healthy and hepatitis B virus-liver disease (HBV-LD), a question is prompted whether omics features could be extracted to distinguish these samples. The IVF-related microbiota derived from the omics data was classified into two enterotype sets, whereas the genomics-based enterotypes were poorly overlapped with the proteomics-based one in either distribution of microbiota or of IVFs. There is lack of molecular features in these enterotypes to specifically recognize healthy or HBV-LD. Running machine learning against the omics data sought the appropriate models to discriminate the healthy and HBV-LD IVFs based on selected genes or proteins. Although a single omics dataset is basically workable in such discrimination, integration of the two datasets enhances discrimination efficiency. The protein features with higher frequencies in the models are further compared between healthy and HBV-LD based on their abundance, bringing about three potential protein biomarkers. This study highlights that integration of metaomics data is beneficial for a molecular discriminator of healthy and HBV-LD, and reveals the IVF samples are valuable for microbiome in a small cohort.

Membrane contact probability: An essential and predictive character for the structural and functional studies of membrane proteins.

One of the unique traits of membrane proteins is that a significant fraction of their hydrophobic amino acids is exposed to the hydrophobic core of lipid bilayers rather than being embedded in the protein interior, which is often not explicitly considered in the protein structure and function predictions. Here, we propose a characteristic and predictive quantity, the membrane contact probability (MCP), to describe the likelihood of the amino acids of a given sequence being in direct contact with the acyl chains of lipid molecules. We show that MCP is complementary to solvent accessibility in characterizing the outer surface of membrane proteins, and it can be predicted for any given sequence with a machine learning-based method by utilizing a training dataset extracted from MemProtMD, a database generated from molecular dynamics simulations for the membrane proteins with a known structure. As the first of many potential applications, we demonstrate that MCP can be used to systematically improve the prediction precision of the protein contact maps and structures.

Bartonella rochalimae, B. grahamii, B. elizabethae, and Wolbachia spp. in Fleas from Wild Rodents near the China-Kazakhstan Border.

The Alataw Pass, near the Ebinur Lake Wetland (northwest of China) and Taldykorgan (east of Kazakhstan), is a natural habitat for wild rodents. To date, little has been done on the surveillance of Bartonella spp. and Wolbachia spp. from fleas in the region. Here we molecularly detected Bartonella spp. and Wolbachia spp. in wild rodent fleas during January and October of 2016 along the Alataw Pass-Kazakhstan border. A total of 1,706 fleas belonging to 10 species were collected from 6 rodent species. Among the 10 flea species, 4 were found to be positive for Wolbachia, and 5 flea species were positive for Bartonella. Molecular analysis indicated that i) B. rochalimae was firstly identified in Xenopsylla gerbilli minax and X. conforms conforms, ii) B. grahamii was firstly identified in X. gerbilli minax, and iii) B. elizabethae was firstly detected in Coptopsylla lamellifer ardua, Paradoxopsyllus repandus, and Nosopsyllus laeviceps laeviceps. Additionally, 3 Wolbachia endosymbionts were firstly found in X. gerbilli minax, X. conforms conforms, P. repandus, and N. laeviceps laeviceps. BLASTn analysis indicated 3 Bartonella species showed genotypic variation. Phylogenetic analysis revealed 3 Wolbachia endosymbionts were clustered into the non-Siphonaptera Wolbachia group. These findings extend our knowledge of the geographical distribution and carriers of B. rochalimae, B. grahamii, B. elizabethae, and Wolbachia spp. In the future, there is a need for China-Kazakhstan cooperation to strengthen the surveillance of flea-borne pathogens in wildlife.

Cell behaviors underlying Myxococcus xanthus aggregate dispersal.

IMPORTANCE: Understanding the processes behind bacterial biofilm formation, maintenance, and dispersal is essential for addressing their effects on health and ecology. Within these multicellular communities, various cues can trigger differentiation into distinct cell types, allowing cells to adapt to their specific local environment. The soil bacterium Myxococcus xanthus forms biofilms in response to starvation, marked by cells aggregating into mounds. Some aggregates persist as spore-filled fruiting bodies, while others disperse after initial formation for unknown reasons. Here, we use a combination of cell tracking analysis and computational simulations to identify behaviors at the cellular level that contribute to aggregate dispersal. Our results suggest that cells in aggregates actively determine whether to disperse or persist and undergo a transition to sporulation based on a self-produced cue related to the aggregate size. Identifying these cues is an important step in understanding and potentially manipulating bacterial cell-fate decisions.

Sequelae of long COVID, known and unknown: A review of updated information.

Over three years have passed since the COVID-19 pandemic started. The dangerousness and impact of COVID-19 should definitely not be ignored or underestimated. Other than the symptoms of acute infection, the long-term symptoms associated with SARS-CoV-2 infection, which are referred to here as "sequelae of long COVID (LC)", are also a conspicuous global public health concern. Although such sequelae were well-documented, the understanding of and insights regarding LC-related sequelae remain inadequate due to the limitations of previous studies (the follow-up, methodological flaws, heterogeneity among studies, etc.). Notably, robust evidence regarding diagnosis and treatment of certain LC sequelae remain insufficient and has been a stumbling block to better management of these patients. This awkward situation motivated us to conduct this review. Here, we comprehensively reviewed the updated information, particularly focusing on clinical issues. We attempt to provide the latest information regarding LC-related sequelae by systematically reviewing the involvement of main organ systems. We also propose paths for future exploration based on available knowledge and the authors' clinical experience. We believe that these take-home messages will be helpful to gain insights into LC and ultimately benefit clinical practice in treating LC-related sequelae.

CD4-CD8-T cells contribute to the persistence of viral hepatitis by striking a delicate balance in immune modulation.

Viral hepatitis remains the most common cause of liver disease and a major public health problem. Here, we focus on the role of CD4 CD8 double negative T (DN T) cells involved in the mechanisms of viral persistence in hepatitis. C3H/HeJ mice infected with murine hepatitis virus strain 3 (MHV-3) were used to display chronic viral hepatitis. DN T cells dramatically increased in MHV-3 infected mice. Adoptive transfer of DN T cells from MHV-3 infected mice led to a significant increase in mice survival. The DN T cells with production of IFN-γ and IL-2 are able to kill virus-specific CD8(+) T cells via the Fas/FasL dependent pathway. The delicate balance of multiple effects of DN T cells may lead to viral persistence in MHV-3 induced hepatitis. In short, our study identified DN T cells contributing to viral persistence in MHV-3 induced hepatitis in C3H/HeJ mice, which provides a rationale for modulating DN T cells for the management of viral hepatitis.

Identification and Validation of Potential Candidate Genes of Colorectal Cancer in Response to Fusobacterium nucleatum Infection.

Objective: Recent investigations revealed the relationship between Fusobacterium nucleatum (Fn) infection and colorectal cancer (CRC). However, how the host genes changes contribute to CRC in response to Fn infection remains largely unknown. Materials and methods: In the present study, we aimed to comprehensively analyze microarray data obtained from a Caco-2 infection cell model using integrated bioinformatics analysis and further identify and validate potential candidate genes in Fn-infected Caco-2 cells and CRC specimens. Results: We identified 10 hub genes potentially involved in Fn induced tumor initiation and progression. Furthermore, we demonstrated that the expression of centrosomal protein of 55 kDa (CEP55) is significantly higher in Fn-infected Caco-2 cells. Knocking down of CEP55 could arrest the cell cycle progression and induce apoptosis in Fn-infected Caco-2 cells. The expression of CEP55 was positively correlated with the Fn amount in Fn-infected CRC patients, and these patients with high CEP55expression had an obviously poorer differentiation, worse metastasis and decreased cumulative survival rate. Conclusion: CEP55 plays an important role in Fn-infected colon cancer cell growth and cell cycle progression and could be used as a new diagnostic and prognostic biomarker for Fn-infected CRC.

Theileria, Hepatozoon and Taenia infection in great gerbils (Rhombomys opimus) in northwestern China.

The great gerbil (Rhombomys opimus), widely distributed in Asia, is a natural reservoir for Yersinia pestis, Leishmania donovani and some species of helminths. In this study, 188 great gerbils were sampled in Alataw City and Manas County, northwestern China, and tested for the presence of Theileria, Hepatozoon and Taenia species by molecular methods. Theileria sp., named as "Candidatus Theileria xinjiangensis", was detected in heart, liver, spleen, lung, and kidney of 6.9% rodents. Six genotypes of "Taenia sp. Rhombomys opimus", which were close to Taenia laticollis (87.3-94.0% identities), were detected in cyst liquid of 5.3% rodents. "Hepatozoon ayorgbor-like" haemogregarines was detected in spleens of 1.6% rodents. To our best knowledge, Candidatus Theileria xinjiangensis, Hepatozoon ayorgbor-like and genotypes of "Taenia sp. Rhombomys opimus" were found for the first time in the great gerbil. These results extend our knowledge on the diversity and pathogenesis of Theileria, Hepatozoon and Taenia species.

Quantification of Myxococcus xanthus Aggregation and Rippling Behaviors: Deep-Learning Transformation of Phase-Contrast into Fluorescence Microscopy Images.

Myxococcus xanthus bacteria are a model system for understanding pattern formation and collective cell behaviors. When starving, cells aggregate into fruiting bodies to form metabolically inert spores. During predation, cells self-organize into traveling cell-density waves termed ripples. Both phase-contrast and fluorescence microscopy are used to observe these patterns but each has its limitations. Phase-contrast images have higher contrast, but the resulting image intensities lose their correlation with cell density. The intensities of fluorescence microscopy images, on the other hand, are well-correlated with cell density, enabling better segmentation of aggregates and better visualization of streaming patterns in between aggregates; however, fluorescence microscopy requires the engineering of cells to express fluorescent proteins and can be phototoxic to cells. To combine the advantages of both imaging methodologies, we develop a generative adversarial network that converts phase-contrast into synthesized fluorescent images. By including an additional histogram-equalized output to the state-of-the-art pix2pixHD algorithm, our model generates accurate images of aggregates and streams, enabling the estimation of aggregate positions and sizes, but with small shifts of their boundaries. Further training on ripple patterns enables accurate estimation of the rippling wavelength. Our methods are thus applicable for many other phenotypic behaviors and pattern formation studies.

Low circadian clock genes expression in cancers: A meta-analysis of its association with clinicopathological features and prognosis.

BACKGROUND: Per1, Per2, Per3, Cry1, Cry2, Bmal1, Npas2 and CLOCK genes are the eight core circadian clock genes. Low expression of these circadian clock genes plays an important role in the progression of cancers. However, its clinicopathological and prognostic value in patients with cancers remains controversial and inconclusive. We performed a meta-analysis of studies assessing the clinicopathological and prognostic significance of low expression of these genes in cancers. METHODS: Relevant studies were searched from the Cochrane Central Register of Controlled Trials, Embase, EBSCO, Ovid, PubMed, Science Direct, Wiley Online Library database, CNKI and Wan Fang database. The meta-analysis was performed by using STATA version 12 software. A random-effect model was employed to evaluate all pooled hazard ratios (HRs) and odd ratios (ORs). RESULTS: A total of 36 studies comprising 7476 cases met the inclusion criteria. Meta-analysis suggested that low expression of Per1 was associated with poor differentiation (Per1: OR=2.30, 95%CI: 1.36∼3.87, P=0.002) and deeper invasion depth (Per1: OR=2.12, 95%CI: 1.62∼2.77, Ρ<0.001); low Per2 expression was correlated with poor differentiation (Per2: OR=2.41, 95%CI: 1.53∼3.79, Ρ<0.001), worse TNM stage (Per2:OR=3.47, 95%CI: 1.88∼6.42, P<0.001) and further metastasis (Per2:OR=2.35, 95%CI: 1.35∼4.11, Ρ=0.003). Furthermore, the results revealed that low expressions of Per1 and Per2 were also correlated with poor overall survival of cancers (Per1: HR=1.35, 95%CI: 1.06∼1.72, P=0.014; Per2: HR=1.43, 95%CI: 1.10∼1.85, P=0.007). Subgroup analysis indicated that low Per1 and Per2 expressions were especially associated with poor prognosis of gastrointestinal caners (Per1: HR=1.33, 95%CI: 1.14∼1.55, Ρ<0.001, Ι2=4.2%; Per2: HR=1.62, 95%CI: 1.25∼2.18, P<0.001, I2=0.0%). CONCLUSIONS: Our study suggested that low Per1, Per2 and Npas2 expression played a distinct and crucial role in progression of cancers. Low expressions of Per1 and Per2 could serve as unfavorable indicators for cancers prognosis, especially for gastrointestinal cancers.

Solvate of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-Hexaazaisowurtzitane (CL-20) with both N2 O4 and Stable NO2 Free Radical.

A new solvate of a powerful explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and liquid oxidizer N2 O4 has been synthesized. When stored at room temperature, the white crystals turn yellowish brown, which indicates partial dissociation of N2 O4 with the formation of a stable NO2 free radical, which is confirmed by ESR spectroscopy. The resulting solvate was analyzed by powder X-ray diffraction, IR-spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The vapor pressure of NO2 above the solvate crystals is similar to the pressure above common hydrates. The presence of the NO2 radical does not affect the thermal stability of CL-20. However, under closed conditions, NO2 increases the rate of the autocatalytic decomposition reaction. The kinetics of this reaction at the surface temperature determine the burning rate of the solvate. The novel solvate has a high density (1.98 g cm-3 ), a high predicted detonation velocity and pressure, and sensitivity to impact slightly higher to that of ϵ-CL-20.

[Role of CD4-CD8- T cells in the murine hepatitis virus type 3 induced chronic viral hepatitis].

OBJECTIVE: To investigate role of CD4-CD8- T cells in murine hepatitis virus type 3 (MHV-3) induced chronic viral hepatitis in C3H/Hej mice and to identify their surface markers. METHODS: Thirty C3H/Hej mice received 10 Pfu MHV-3 intraperitoneally, the CD4-CD8- T cells were isolated using magnetic bead sorting on 0, 4, 15, 30, 40 days post MHV-3 infection. The cytotoxic effects of CD4-CD8- T cells on normal and infected hepatocytes, CD8+ T cells and unrelated-virus (murine cytomegalovirus, MCMV) infected CD8+ T cells were examined by non-radioactive cytotoxicity assay. The surface markers of CD4-CD8- T cells were determined by flow cytometry. RESULTS: MHV-3 infected CD4-CD8- T cells showed significant cytotoxic effect on CD8+ T cells, but not on infected hepatocytes or MCMV infected CD8+ T cells. The analysis of cell surface markers demonstrated that the CD4-CD8- T cells are a completely new T cell subset. CONCLUSIONS: CD4-CD8- T cells have significant cytotoxic effect on virus specific CD8+ T cells in MHV-3 infected C3H/Hej mice, which suggests that CD4-CD8- T cells have immune modulatory functions in the development of chronic viral hepatitis. The phenotype of these CD4-CD8- T cells detected by flow cytometry is TCR alpha beta +CD3+CD4- CD8- CD25- CD28- CD30- CD44+.

Suppression of FasL expression in tumor cells and preventing TNF-induced apoptosis was better for immune cells survival.

OBJECTIVE: To elucidate if Fas/FasL signal pathway participates in the immune escape of tumor cells, and if contemporarily preventing Fas/FasL and TNF-induced apoptosis is better for immune cells survival than just blocking Fas/FasL-induced apoptotic signal. METHODS: Suppression of FasL expression in mouse H22 hepatocellular cancer cells by siRNA technique. Wild-type Ad5 14.7K gene was amplified by PCR and transduced into Jurkat T cells. Detecting apoptosis of target Jurkat cells by Flow Cytometry. Detection of TNF-alpha in the culture supernatant of H22 cells by ELISA. FasL and 14.7K gene expression in stably transfected or transduced clones were determined by western blotting. RESULTS: FasL expression in H22 cells was down-regulated following stable transfection with a plasmid encoding antisense FasL cDNA. Down-regulation of FasL expression in H22 cells had no effect on tumor growth in vitro. There was an apparent decrease in the number of apoptotic Jurkat T cells following coculture with transfected H22 cells, relative to coculture with FasL-expressing untransfected cells. Compared with untransduced Jurkat cells, apoptotic rates in 14.7K transduced Jurkat cells were significantly reduced in three different E/T ratios (P < 0.01), respectively. CONCLUSIONS: Fas/FasL signal pathway participated in the immune escape of tumor cells by inducing immune cells apoptosis. Reducing the expression of FasL in tumor cells can decrease the apoptotic rate of immune cells. Further blocking of apoptotic signal pathway of immune cells by preventing TNF-induced apoptosis can increase the survival of immune cells.

Suppression of FasL expression in tumor cells and preventing tumor necrosis factor-induced apoptosis by adenovirus 14.7K is an effective escape mechanism for immune cells.

To elucidate if the Fas/FasL signal pathway participates in the immune escape of tumor cells, and if contemporary Fas/FasL and tumor necrosis factor (TNF))-induced apoptosis is better for immune cell survival than just blocking Fas/FasL-induced apoptotic signal. FasL expression in mouse H22 hepatocellular cancer cells was suppressed by the siRNA technique. The wild-type Ad5 14.7K gene was amplified by polymerase chain reaction and transduced into Jurkat T-cells. Apoptosis of target Jurkat cells was detected by flow cytometry. TNF-alpha in the culture supernatant of H22 cells by ELISA was seen. FasL and 14.7K gene expression in stably transfected or transduced clones were determined by Western blotting. As a result, FasL expression in H22 cells was down-regulated after stable transfection with a plasmid encoding antisense FasL cDNA. Down-regulation of FasL expression in H22 cells had no effect on tumor growth in vitro. There was an apparent decrease in the number of apoptotic Jurkat T-cells after coculture with transfected H22 cells, relative to coculture with FasL-expressing untransfected cells. Compared with untransduced Jurkat cells, apoptotic rates in 14.7K-transduced Jurkat cells were significantly reduced in three different E/T ratios (P < 0.01), respectively. We conclude that Fas/FasL signal pathway participates in the immune escape of tumor cells by inducing immune cells apoptosis. Reducing the expression of FasL in tumor cells can decrease the apoptotic rate of immune cells, further blocking the apoptotic signal pathway of immune cells by preventing TNF-induced apoptosis can increase the survival of immune cells.

Applied value of monitoring serum hepcidin in differential diagnosis of infection versus tumor fevers.

The applied value of serum hepcidin in differential diagnosis of infection fevers versus tumor fevers was explored. A total of 432 fever patients were selected according to the domestic fever of unknown origin (FUO) diagnostic criteria from our hospital between June 2010 and November 2013. Venous blood samples were taken on the day 1, 5, 10 after admission. The infection group (98 cases) and the tumor group (50 cases) were set up based on the clinical and laboratory findings. ELISA was used to determine the serum hepcidin and IL-6 levels. SPSS 13.0 was used for statistical analysis. Hepcidin showed obvious descending trend on the 10th day in both the bacterial infection group (66 cases) and the virus infection group (32 cases), and the descending trend was similar to that of inflammatory indexes such as procalcitonin (PCT), hypersensitive C-reactive protein (h-CRP), erythrocyte sedimentation rate (ESR), white blood cell (WBC), and ferritin. Serum hepcidin showed no obvious differences in the tumor group on the day 1, 5, 10 after admission. In the infection groups, serum hepcidin was positively correlated with IL-6 (r=0.687, P=0.000) and CRP (r=0.487, P=0.026), but had a poor correlation with blood sedimentation, ferritin, PCT and WBC (P>0.05). Monitoring dynamic changes of hepcidin and related inflammatory factors in patients with fever is expected to be used for clinical identification of infection fever and tumor fever.

The diagnostic value of neutrophil gelatinase-associated lipocalin and hepcidin in bacteria translocation of liver cirrhosis.

OBJECTIVE: Bacterial translocation (BT) or bacterial DNA (bactDNA) translocation is a critical pathogenesis mechanism of spontaneous bacterial peritonitis. Studies of BT or bactDNA translocation are limited in humans. Neutrophil gelatinase associated lipocalin (NGAL) can efficiently distinguish bacterial and nonbacterial ascites in ascitic patients. Hepcidin is a useful marker of bacterial infection in the late-onset sepsis. However, the relationship between NGAL, hepcidin and BT was still unclear. In present study, the levels of NGAL, hepcidin and their relationship with BT or bactDNA translocation were investigated. MATERIAL AND METHODS: Weekly doses of carbon tetrachloride (CCl4) were given to induce liver cirrhosis in Sprague-Dawley rats. Trypticase (blood) soy agars were used to culture bacteria. BactDNA was sequenced by ABIPRISM 310 automated sequencer. The levels of NGAL and hepcidin were assessed by ELISA. Receiver operating characteristic (ROC) curve was used to determine the cut-off values and compare the diagnostic performance of NGAL and hepcidin. RESULTS: 56 cirrhotic and 10 normal rats were included in this study. The levels of both two biomarkers were significantly higher in BT or bactDNA translocation group compared to non-translocation group. The area under ROC curve for the diagnosis of BT was 0.910 for serum NGAL, 0.858 for serum hepcidin and 0.940 for their combination, whereas that for the diagnosis of bactDNA translocation was 0.906 for NGAL, 0.779 for hepcidin and 0.950 for their combination, respectively. The combination of NGAL and hepcidin improved the ability to detect BT or bactDNA presence in MLNs and ascites. CONCLUSION: BT and the presence of bactDNA in MLNs were observed in a rat cirrhotic model. Serum NGAL and hepcidin can serve as sensitive and specific tests for diagnosis of BT or bactDNA translocation. NGAL in combination with hepcidin can improve the accuracy of diagnosis.

Diabetes mellitus and the neutrophil to lymphocyte ratio predict overall survival in non-viral hepatocellular carcinoma treated with transarterial chemoembolization.

Diabetes mellitus (DM) and systemic inflammation are closely associated with the development of hepatocellular carcinoma (HCC). However, the prognostic significance of DM on HCC remains controversial. The main purpose of the present study was to evaluate the effects of DM and the systemic inflammation-based neutrophil to lymphocyte ratio (NLR) on the overall survival (OS) rate of non-viral HCC patients treated with transarterial chemoembolization (TACE). A retrospective analysis of 138 patients with HCC, who were diagnosed between 2002 and 2012 with non-viral causes and who later underwent TACE, was performed. Among these patients, 34 (24.6%) had pre-existing DM and 46 (33.3%) exhibited an elevated baseline NLR (≥5). The multivariate analysis showed that DM, the NLR and a portal vein tumor thrombus (PVTT) were independent predictors for a poor OS rate (P<0.05). The patients with DM and an elevated NLR exhibited a poorer OS rate when compared with patients without these factors. In addition, there was a significant stepwise improvement in the OS rate of patients with DM and an elevated NLR, and in patients with only one of these factors compared with patients without either (P<0.01). Finally, DM was significantly correlated with PVTT and elevated γ-glutamyl transpeptidase levels, while the NLR was independently associated with PVTT and tumor multiplicity (P<0.05). The present study revealed that DM, baseline NLR and PVTT are independent indicators of the OS rate in non-viral HCC patients treated with TACE. DM and NLR may affect the OS rate by promoting the malignant progression of HCC. The combination of DM and NLR appears to be a stronger predictor for OS than DM or NLR alone.

Pseudomonas aeruginosa quorum-sensing molecule N-(3-oxododecanoyl) homoserine lactone attenuates lipopolysaccharide-induced inflammation by activating the unfolded protein response.

N-3-oxododecanoyl homoserine lactone (3-oxo-C12-HSL), a quorum-sensing signal molecule produced by Pseudomonas aeruginosa (P. aeruginosa), is involved in the expression of bacterial virulence factors and in the modulation of host immune responses by directly disrupting nuclear factor-κB (NF-κB) signaling and inducing cell apoptosis. The unfolded protein response (UPR) triggered by endoplasmic reticulum (ER) stress may suppress inflammatory responses in the later phase by blocking NF-κB activation. It was recently demonstrated that 3-oxo-C12-HSL may induce UPR in human aortic endothelial cells (HAECs). Therefore, 3-oxo-C12-HSL may also inhibit NF-κB activation and suppress inflammatory responses by activating UPR. However, the possible underlying mechanism has not been fully elucidated. Accordingly, we investigated the effects of 3-oxo-C12-HSL on cellular viability, UPR activation, lipopolysaccharide (LPS)-induced NF-κB activation and inflammatory response in the RAW264.7 mouse macrophage cell line. Treatment with 6.25 µM 3-oxo-C12-HSL was not found to affect the viability of RAW264.7 cells. However, pretreating RAW264.7 cells with 6.25 µM 3-oxo-C12-HSL effectively triggered UPR and increased the expression of UPR target genes, such as CCAAT/enhancer-binding protein ß (C/EBP ß) and CCAAT/enhancer-binding protein-homologous protein (CHOP). The expression of C/EBP ß and CHOP was found to be inversely correlated with LPS-induced NF-κB activation. 3-Oxo-C12-HSL pretreatment was also shown to inhibit LPS-stimulated proinflammatory cytokine production. Hence, 3-oxo-C12-HSL may attenuate LPS-induced inflammation via UPR-mediated NF-κB inhibition without affecting cell viability. This may be another mechanism through which P. aeruginosa evades the host immune system and maintains a persistent infection.

siRNA-mediated gene silencing of MexB from the MexA-MexB-OprM efflux pump in Pseudomonas aeruginosa.

To gain insights into the effect of MexB gene under the short interfering RNA (siRNA), we synthesized 21 bp siRNA duplexes against the MexB gene. RT-PCR was performed to determine whether the siRNA inhibited the expression of MexB mRNA. Changes in antibiotic susceptibility in response to siRNA were measured by the E-test method. The efficacy of siRNAs was determined in a murine model of chronic P. aeruginosa lung infection. MexB-siRNAs inhibited both mRNA expression and the activity of P. aeruginosa in vitro. In vivo, siRNA was effective in reducing the bacterial load in the model of chronic lung infection and the P. aeruginosa-induced pathological changes. MexB-siRNA treatment enhanced the production of inflammatory cytokines in the early infection stage (P＜0.05). Our results suggest that targeting of MexB with siRNA appears to be a novel strategy for treating P. aeruginosa infections.