Antimicrobial Activity Assay of Liposomal Lipopolysaccharide Extracted from Escherichia coli

Escherichia coli (E. coli) is a bacterial bacillus known to be negative for the gram dye, and it is part of the normal flora inside the human body. The current study aimed to investigate the possibility of using lipopolysaccharides (LPS) as an antimicrobial agent. A total of 30 isolates of E. coli were collected from 100 specimens of urine isolated from patients with recurrent urinary tract infections (UTIs) referring to Al-Sadr Teaching Hospital. The samples were cultured on identification media; thereafter, they were diagnosed according to the phenotypic form, biochemical tests, and finally by VITK-2. The results of the prevalence of E. coli isolates illustrated that from 30 isolates of E. coli which were collected from 100 urine specimens, 14 (46.6%), 6 (20%), and 10 (33.3%) cases belonged to the urinary tract infections, kidney stones, and urinary catheter samples, respectively. The isolates displayed multiple drug resistance (MDR) to most of the antibiotics used in the study. Therefore, the lipopolysaccharide extracted from E. coli was used as an antimicrobial agent. The recorded data obtained from the polymerase chain reaction (PCR) for WaaA, WaaC, wamB, and wabG genes demonstrated that the isolates possessed biosynthesis genes for LPS. The results indicated that LPS at concentrations of 150, 250, and 500 μg/ml has as an anti-growth agent for Klebsiella pneumonia, Proteus mirabilis, Salmonella typhi, Pseudomonas aeruginosa, Bacillus subtilis, Staph aureus, and candida albicans. The highest inhibitory effect was observed on K. pneumonia, P. mirabilis, S. typhi, B. subtilis, and C. albicans, as compared to the control antimicrobials agents (Amoxicillin, Nystatin). The LPS loaded on liposome nanoparticles can open new horizons in medicine by its inclusion in the manufacture of broad-spectrum antibiotics.

Gut-derived lipopolysaccharide promotes alcoholic hepatosteatosis and subsequent hepatocellular carcinoma by stimulating neutrophil extracellular traps through TLR4

Background/Aims

Binge drinking leads to many disorders, including alcoholic hepatosteatosis, which is characterized by intrahepatic neutrophil infiltration and increases the risk of hepatocellular carcinoma (HCC). Molecular mechanisms may involve the migration of bacterial metabolites from the gut to the liver and the activation of neutrophil extracellular traps (NETs).

Methods

Serum samples from both binge drinking and alcohol-avoiding patients were analyzed. Mouse models of chronic plus binge alcohol-induced hepatosteatosis and HCC models were used.

Results

A marker of NETs formation, lipopolysaccharide (LPS), was significantly higher in alcoholic hepatosteatosis and HCC patients and mice than in controls. Intrahepatic inflammation markers and HCC-related cytokines were decreased in mice with reduced NET formation due to neutrophil elastase (NE) deletion, and liver-related symptoms of alcohol were also alleviated in NE knockout mice. Removal of intestinal bacteria with antibiotics led to decreases in markers of NETs formation and inflammatory cytokines upon chronic alcohol consumption, and development of alcoholic hepatosteatosis and HCC was also attenuated. These functions were restored upon supplementation with the bacterial product LPS. When mice lacking toll-like receptor 4 (TLR4) received chronic alcohol feeding, intrahepatic markers of NETs formation decreased, and hepatosteatosis and HCC were alleviated.

Conclusions

Formation of NETs following LPS stimulation of TLR4 upon chronic alcohol use leads to increased alcoholic steatosis and subsequent HCC.

Brain-derived neurotrophic factor enhances the therapeutic effect of oleuropein in the lipopolysaccharide-induced models of depression

Major depressive disorder (MDD) is a heterogeneous disease, involving multiple mechanisms and factors, which commonly result in injury to the psychosocial function of the central nervous system, and even suicidality of patients. However, effective treatment for MDD is still lacking. Oleuropein is a newly discovered natural compound extracted from olive leaves, which has a strong antioxidative effect by reducing the production of reactive oxygen species (ROS). Oleuropein also reduces blood pressure in humans and experimental animals, and protects blood vessels. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family, which supports the function of the central nervous system. BDNF plays an important role in the development of the nervous system via the regulation of cellular differentiation, survival neurogenesis and synaptic plasticity; therefore, we hypothesized that overexpression of BDNF might contribute to the therapeutic effect of oleuropein. Here, we first demonstrated that oleuropein reverses depressive-like behaviour and restores the inflammatory response in a mouse lipopolysaccharide (LPS) model of MDD. We further established a cell model of BDNF overexpression and inhibition in SH-SY5Y cells, and found that the concentration of intercellular calcium was increased after treatment with oleuropein combined with BDNF overexpression, which may be mediated by the BDNF-TrkB-CaMKII signalling pathway. In addition, we observed that the expression of neurotrophic factors, including epidermal growth factor (EGF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4), was increased, which may be mediated by inhibition of the RhoA-ROCK signalling pathway.