Enhanced Biosynthesis of Fatty Acids Contributes to Ciprofloxacin Resistance in Pseudomonas aeruginosa.

Antibiotic-resistant Pseudomonas aeruginosa is insensitive to antibiotics and difficult to deal with. An understanding of the resistance mechanisms is required for the control of the pathogen. In this study, gas chromatography-mass spectrometer (GC-MS)-based metabolomics was performed to identify differential metabolomes in ciprofloxacin (CIP)-resistant P. aeruginosa strains that originated from P. aeruginosa ATCC 27853 and had minimum inhibitory concentrations (MICs) that were 16-, 64-, and 128-fold (PA-R16CIP, PA-R64CIP, and PA-R128CIP, respectively) higher than the original value, compared to CIP-sensitive P. aeruginosa (PA-S). Upregulation of fatty acid biosynthesis forms a characteristic feature of the CIP-resistant metabolomes and fatty acid metabolome, which was supported by elevated gene expression and enzymatic activity in the metabolic pathway. The fatty acid synthase inhibitor triclosan potentiates CIP to kill PA-R128CIP and clinically multidrug-resistant P. aeruginosa strains. The potentiated killing was companied with reduced gene expression and enzymatic activity and the returned abundance of fatty acids in the metabolic pathway. Consistently, membrane permeability was reduced in the PA-R and clinically multidrug-resistant P. aeruginosa strains, which were reverted by triclosan. Triclosan also stimulated the uptake of CIP. These findings highlight the importance of the elevated biosynthesis of fatty acids in the CIP resistance of P. aeruginosa and provide a target pathway for combating CIP-resistant P. aeruginosa.

Glucose-Potentiated Amikacin Killing of Cefoperazone/Sulbactam Resistant Pseudomonas aeruginosa.

Multidrug-resistant Pseudomonas aeruginosa has become one of global threat pathogens for human health due to insensitivity to antibiotics. Recently developed reprogramming metabolomics can identify biomarkers, and then, the biomarkers were used to revert the insensitivity and elevate antibiotic-mediated killing. Here, the methodology was used to study cefoperazone/sulbactam (SCF)-resistant P. aeruginosa (PA-RSCF) and identified reduced glycolysis and pyruvate cycle, a recent clarified cycle providing respiratory energy in bacteria, as the most key enriched pathways and the depressed glucose as one of the most crucial biomarkers. Further experiments showed that the depression of glucose was attributed to reduction of glucose transport. However, exogenous glucose reverted the reduction to elevate intracellular glucose via activating glucose transport. The elevated glucose fluxed to the glycolysis, pyruvate cycle, and electron transport chain to promote downstream proton motive force (PMF). Consistently, exogenous glucose did not promote SCF-mediated elimination but potentiated aminoglycosides-mediated killing since aminoglycosides uptake is PMF-dependent, where amikacin was the best one. The glucose-potentiated amikacin-mediated killing was effective to both lab-evolved PA-RSCF and clinical multidrug-resistant P. aeruginosa. These results reveal the depressed glucose uptake causes the reduced intracellular glucose and expand the application of metabolome-reprogramming on selecting conventional antibiotics to achieve the best killing efficacy.

[Efficacy of BMMSCs on aGVHD and Its Correlation with SerumInflammatory Cytokines in Pediatric Patients with Severe Refractory Acute Graft-Versus-Host Disease].

OBJECTIVE: To investigate the efficacy of bone marrow mesenchymal stem cells (BMMSC) on children with refractory graft-versus-host disease (GVHD) and to judge the efficacy of BMMSC by dynamically monitoring the changes of cytokines in children with GVHD before and after infusion of BMMSC, so as to provide a theoretical basis for clarifying the mechanism of BMMSC. METHODS: 17 children with refractory aGVHD including 7 of grade II, 6 cases of grade III and 4 cases of grade IV after allo-HSCT were enrolled. All the children with aGVHD, who received routine immunosuppressive therapy, but the state of disease not improved, were treated with immunosuppressive drugs combined with BMMSC infusion. Study endpoints included safety of BMMSC infusion, response to BMMSC, and overall response of aGVHD. The serum levels of IL-2α, IL-6, IL-10, IL-8 and TNF-α in aGVHD patients were measured by chemiluminescence before infusion of BMMSCs and Day 7, Day 14 after infusion of BMMSCs. RESULTS: The cumulative median dose of BMMSCs was 5.5 (3.4-11.1) × 106/kg for average of 3.7 times, and the median time of 16.5 (4-95) days for the first infusion of MSCs. In 17 cases of refractory GVHD, 14 responded to treatment, whereas 3 patients failed. The total effective rate was 82.4% and no adverse reactions occurred. Of the 14 survived cases (82.4%), the median follow-up time was 944 (559-1245) days from the first infusion of MSCs. The levels of TNF-α in children with grade II, III and IV GVHD before treatment were 9.5±4.3 pg/ml, 16.3±10.9 pg/ml and 35.8±21.2 pg/ml respectively. The difference between grade II and IV, III and IV was statistically significant (P<0.05). Compared with the ineffective group of BMMSC infusion, the serum TNF-αlevel in the BMMSCs treatment effective group was 10.8±5.6 pg/ml vs 40.6±14.8 pg/ml (t=-3.901, P<0.05) before treatment. In the effective group of BMMSCs infusion, IL-10 20±17.4 pg/ml of day 14 was significantly higher than that 7.3±3.1 pg/ml before the treatment (t=-2.850, P<0.05), while , the serum levels of IL-2α, IL-6, IL-8, TNF-α were not statistically significantly different (P＞0.05). CONCLUSION: The infusion of BMMSC is safe and effective in the treatment of refractory GVHD in children. TNF-αlevel relates with the severity of GVHD. BMMSC may play an anti-GVHD role by up regulating the level of cytokine IL-10 in vivo.

Evaluation of Insulin-mediated Regulation of AKT Signaling in Childhood Acute Lymphoblastic Leukemia.

OBJECTIVE: Hyperglycemia increases the risk of early recurrence and high mortality in some adult blood cancers. In response to increased glucose levels, insulin is secreted, and several studies have shown that insulin-induced AKT signaling can regulate tumor cell proliferation and apoptosis. The AKT pathway is aberrantly activated in adult acute lymphoblastic leukemia (ALL), but the mechanisms underlying this activation and its impact in pediatric patients with ALL are unclear. MATERIALS AND METHODS: We evaluated the insulin-induced chemoresistance and AKT pathway activation by measuring cell proliferation, apoptosis, and other parameters in ALL cell lines (Jurkat and Reh cells), as well as in primary pediatric leukemic cell samples, after culture with insulin, the chemotherapeutic drugs daunorubicin (DNR), vincristine (VCR), and L-asparaginase (L-Asp), or anti-insulin-like growth factor-1 receptor (IGF-1R) monoclonal antibody. RESULTS: DNR, VCR, and L-Asp-induced toxicity in Jurkat and Reh cells was reduced in the presence of insulin. DNR promoted cell proliferation, whereas DNR, VCR, and L-Asp all reduced apoptosis in both cell lines cotreated with insulin compared with that in cell lines treated with chemotherapeutics alone (P<0.05). Furthermore, addition of an anti-IGF-1R monoclonal antibody promoted apoptosis, downregulated IGF-1R expression, and decreased the phosphorylation of AKT, P70S6K, and mTOR intracellular signaling pathway proteins in both cell lines, as well as in primary cultures (P<0.05). CONCLUSIONS: Our results suggest that insulin-induced chemoresistance and activation of the AKT signaling pathway in pediatric ALL cells.