Objective To identify the efficacy small interfering RNA against Pseudomonas aeruginosa expressing MexA-MexB-OprM efflux pumps.Methods Four siRNA ( siRNA1,siRNA2,siRNA3 and siRNA4) against mexB gene were designed and prepared by electricity transference in vitro.MICs of antibiotic combined with efflux pump inhibitors against multiple resistant strain PAO1 and PAO3 were determined by E-test method.The mRNA expression levels of efflux pump gene (mexB) were quantified by real time fluorescent quantitative PCR.Results siRNA expression vectors were constructed success by enzyme cut method.48 after PAO1 and multiple drug resistant PAO3 transfected with siRNA4,the sensibilities to antibiotic were enhanced.48 after PAO1 and multiple drug resistant PAO3 transfected with siRNAl,siRNA2 and siRNA3,the sensibilities to antibiotic didn't change obviously.48 after PAO1 and multiple drug resistant PAO3 ttransfected with siRNA4,the expression level of mexB was decreased obviously (P ＜ 0.05 ).48 after PAO1 and multiple drug resistant PAO3 transfected with siRNA1,siRNA2 and siRNA3,the expression level of mexB didn't change obviously.Conclusion siRNA against Pseudomonas aeruginosa expressing MexA-MexB-OprM efflux pumps enhanced the sensibility to antibiotic and inhibited the expression of mexB gene.Our results demonstrate the using RNAi may be potential targets for novel therapies directed against treatment of antibiotic-resistant infections.

Objective To investigate the effect of quorum sensing autoinducer 3OC12-HSL of Pseudomonas aeruginosa on the apoptosis of Caco-2 cells and its mechanism. Methods Caco-2 cells were incubated with 3OC12-HSL for 4 h and then examined by MTT method for cytoactivities. Flow cytometry was used to analyze apoptosis rate of Caco-2 cells. Expression of apoptosis associated proteins p-p38/MAPK and NF-κB were detected by Western blot. Results After exposure to 3OC12-HSL for 4 h, cytoactivities of Caco-2 cells was reduced(P<0.05) with dose-dependent pattern, and higher dose of 3OC12-HSL leaded to increasing apoptosis rate of Caco-2 cells(P<0.05). 3OC12-HSL raised expression of apoptosis associated proteins p-p38/MAPK and NF-κB detected by Western blot. Conclusion Quorum sensing autoinducer 3OC12-HSL can effect cytoactivities of Caco-2 cells and may induce its apoptosis by enhancing the expression of p-p38/MAPK and NF-κB protein.

The therapeutic effectiveness of nutritional support in the treatment of severe chronic hepatitis and posthepatitic cirrhosis was evaluated. 143 patients with severe chronic hepatitis and 83 with posthepatitic cirrhosis were evaluated with SGA for assessing the nutritional status before the treatment. Patients with severe chronic hepatitis were divided into three groups: group A subject to enteral nutrition (EN) and parenteral nutrition (PN), group B subject to comprehensive treatment (CT)+PN; group C subject to CT+EN. The patients with posthepatitic cirrhosis were divided into two groups: group D receiving CT and group E receiving CT+PN+EN. The function of liver and kidney and nutritional status were monitored to assess the therapy in 6 weeks. The results showed before treatment, over 90 % patients had moderate to severe malnutrition. After nutritional support, the liver function (ALT, T-bil) and nutritional status (TP, TC) in group A was improved significantly as compared with that in groups B and C (P<0.05). Compared with group D, the values of TP and Alb were increased significantly in group E (P<0.05), but the levels of ALT, AST and T-bil had no obvious change. It was suggested that most patients with severe chronic hepatitis or posthepatitic cirrhosis had malnutrition to varying degrees. The nutritional support treatment could obviously improve the nutritional status of these patients, and was helpful to ameliorate the liver function of the patients with severe chronic hepatitis. Among the methods of nutritional support treatment, PN combined with EN had the best effectiveness.

In order to investigate the role of the MexA-MexB-OprM efflux pump system in the pathogenesis of Pseudomonas aeruginosa (PA)-induced pulmonary infection, pulmonary infection models were established by intratracheal injection of K767 (wild type), nalB (MexA-MexB-OprM up-regulated mutant), and ΔmexB (knockout) strains, separately. All mice were treated with Meropenem (intraper Δ itoneal injection, 100 mg/kg body weight, twice every day), and strain-related pathology, bacteria count, cytokine level, myeloperoxidase (MPO, indicator of neutrophil recruitment) activity, and macrophage inflammatory protein-2 (MIP-2) expression were evaluated at early (3rd day post-infection) and late (7th and 14th day post-infection) stages of infection. E-test showed that ΔmexB was more significantly Δ sensitive to panipenan (ETP), meropenem (MP) and imipenem (IP) than K767 and nalB strains. There was no significant difference in sensitivity to cefepime (TM) among the three stains. In contrast to the K767 and nalB groups, the ΔmexB group showed decreased bacteria burden over time and less exte Δ nsive pathological change. Additionally, MPO activity and levels of inflammatory cytokines (IL-1b, IL-12, and TNF-α) were increased at the early stage (day 3) and decreased at the later stage (day 14). Serum MIP-2 expression level was steadily increased in all three groups from early to late stages, but significantly higher in ΔmexB group than in K767 and nalB groups ( Δ P<0.05). In conclusion, the MexA-MexB-OprM efflux pump system might play an important role in PA-induced chronic pulmonary infection. High expression of the MexA-MexB-OprM efflux pump could increase antibacterial resistance and promote infection.

Objective To investigate the effect and mechanism of siHybrids technique on inhibiring the efflux pump gene mexB of Pseudomonas aeruginosa PAO1 in vitro. MethodsTargeting the efflux pump gene mexB of Pseudomonas aeruginosa PAO1 ,we designed and synthesized three siHybrids molecule and one negative scamble siHybrids molecule. Pseudomonas aeruginosa PAO1 were intervened by the siHybrids molecules in 50 nmol/L, respectively. And the experiments were made of control groups[blank and scamble (sc) -001]and intervened groups[siHybrids( si ) -001, siHybrids( si ) -002 and siHybrids(si) -003]of Pseudomonas aeruginosa PAO1. The targeting efflux pump gene mexB mRNA expressions of Pseudomonas aeruginosa PAO1, including all groups, were measured by real-time PCR in 12 h and 24 h after interference in vitro. Further, the minimal inhibitory concentration (MIC) of chlormycetinCP, erythrocin( EM ), levofloxacin ( L-OFLX), ceftazidime ( CAZ), meropenem (MER) to those groups were detected by using Mueller-Hinton broth dilution before and after interference. ResultsThe relative mexB mRNA amounts of Pseudomonas aeruginosa PAO1 intervened by different siHybrids were not much more different from each other after 12 h,but the expression of mexB mRNA of the intervened group ( si-001 ,si-002 ,si-003 ) was much lower than control groups after interference for 24 h. The relative mexB mRNA amounts, comparing 12 h with 24 h, we would find the blank control and negative control submit escalating trend. And the intervened control ,three different siHybrids were all with a downward tendency. However, in presence of 50 nmol/L siHybrids, the minimal inhibitory concentration(MIC) of CP, EM, L-OFLX, CAZ, MER to those controls were not much more different before and after interference. Conclusion On level of the mRNA expressions, siHybrids could inhibit the efflux pump gene mexB of Pseudomonas aeruginosa PAO1 in vitro, and within 24 h would be able to function effectively. Further, the effect was time-dependent.

Objective To investigate whether Pseudomonas aeruginosa pvdQ( PA2385 ) gene reveals altered antibiotic susceptibility under swarming conditions. Methods The plasmid pME6032 with pvdQ gene was constructed and identified, then transformed into Pseudomonas aeruginosa PAO1 by the electroporation, building pvdQ overexpression strain. Using the same method building pME6032-PAO1 strain.Bacteria were inoculated in LB overnight , measuring the colony diameter of the swarming zone . Results Strains of pvdQ overexpression was successfully constructed by real-time PCR. Comparison of two strains of the swarming motility of change in diameter: The result showed that PAO1 and pvdQ overexpression strains can both improve the antibiotics resistance. Swarmer cells of pvdQ overexpression strain exhibited a 2- to 4-fold increase in antibiotic resistance toward ceftazidime,ciprofloxacin, meropenem and polymyxin B compared to PAO1 on BM2-swarming agar plates. Conclusion pvdQ gene played an important role in elevating the antibiotics resistance, which through prarticipated in the swarmer cell differentiation.

ObjectiveTo investigate the alteration of MexB protein expression by plasmid containing siRNA template strand was transformed into Pseudomonas aeruginosa.Methods siRNA molecules specifically against mexB were designed and ligated into pGPU6/GFP/Neo vector to construct the recombinant plasmid pGPU6/GFP/Neo-siRNA.MexB gene was cloned into expression vector pET22b+ to construct plasmid pET22b+/mexB,the recombinant expression plasmid was transformed into E.coli BL21 (DE3)plysS and protein MexB was induced to express,then purified protein MexB was used to prepare specific antibodies in rabbits.The plasmids with siRNA molecules specifically against mexB were transformed into wild type strain,clinical multiresistant strain and mexB overexpression strain of Pseudomonas aeruginosa by electroporation respectively,and the changes of the expression of MexB were detected in 8,12,24 h respectively by Western blot.ResultspGPU6/GFP/Neo-siRNA was constructed successfully.Protein MexB was expressed successfully and the rabbit polyclonal antibodies against MexB was prepared well.The gene silence of mexB by siRNA molecules was effective in the three strains of Pseudomonas aeruginosa,but it depended on the silencing time.ConclusionThe expression of MexB was reduced in 8 h and 12 h,but in 24 h,the expression was unchanged.

In order to investigate the role of the MexA-MexB-OprM efflux pump system in the pathogenesis of Pseudomonas aeruginosa (PA)-induced pulmonary infection, pulmonary infection models were established by intratracheal injection of K767 (wild type), nalB (MexA-MexB-OprM up-regulated mutant), and ΔmexB (knockout) strains, separately. All mice were treated with Meropenem (intraper Δ itoneal injection, 100 mg/kg body weight, twice every day), and strain-related pathology, bacteria count, cytokine level, myeloperoxidase (MPO, indicator of neutrophil recruitment) activity, and macrophage inflammatory protein-2 (MIP-2) expression were evaluated at early (3rd day post-infection) and late (7th and 14th day post-infection) stages of infection. E-test showed that ΔmexB was more significantly Δ sensitive to panipenan (ETP), meropenem (MP) and imipenem (IP) than K767 and nalB strains. There was no significant difference in sensitivity to cefepime (TM) among the three stains. In contrast to the K767 and nalB groups, the ΔmexB group showed decreased bacteria burden over time and less exte Δ nsive pathological change. Additionally, MPO activity and levels of inflammatory cytokines (IL-1b, IL-12, and TNF-α) were increased at the early stage (day 3) and decreased at the later stage (day 14). Serum MIP-2 expression level was steadily increased in all three groups from early to late stages, but significantly higher in ΔmexB group than in K767 and nalB groups ( Δ P<0.05). In conclusion, the MexA-MexB-OprM efflux pump system might play an important role in PA-induced chronic pulmonary infection. High expression of the MexA-MexB-OprM efflux pump could increase antibacterial resistance and promote infection.
Animals ; Bacterial Outer Membrane Proteins ; metabolism ; Lung ; microbiology ; Membrane Transport Proteins ; metabolism ; Mice ; Mice, Inbred BALB C ; Pseudomonas Infections ; metabolism ; microbiology ; Pseudomonas aeruginosa ; metabolism

The therapeutic effectiveness of nutritional support in the treatment of severe chronic hepatitis and posthepatitic cirrhosis was evaluated. 143 patients with severe chronic hepatitis and 83 with posthepatitic cirrhosis were evaluated with SGA for assessing the nutritional status before the treatment. Patients with severe chronic hepatitis were divided into three groups: group A subject to enteral nutrition (EN) and parenteral nutrition (PN), group B subject to comprehensive treatment (CT) +PN; group C subject to CT+ EN. The patients with posthepatitic cirrhosis were divided into two groups: group D receiving CT and group E receiving CT+PN+EN. The function of liver and kidney and nutritional status were monitored to assess the therapy in 6 weeks. The results showed before treatment, over 90 % patients had moderate to severe malnutrition. After nutritional support, the liver function (ALT, T-biil) and nutritional status (TP, TC) in group A was improved significantly as compared with that in groups B and C (P＜0.05). Compared with group D,the values of TP and Alb were increased significantly in group E (P＜0.05), but the levels of ALT, AST and T-bil had no obvious change. It was suggested that most patients with severe chronic hepatitis or posthepatitic cirrhosis had malnutrition to varying degrees. The nutritional support treatment could obviously improve the nutritional status of these patients, and was helpful to ameliorate the liver function of the patients with severe chronic hepatitis. Among the methods of nutritional support treatment, PN combined with EN had the best effectiveness.