Helicobacter pylori-derived outer membrane vesicles suppress liver autophagy: A novel mechanism for H. pylori-mediated hepatic disorder.

BACKGROUND: Helicobacter pylori outer membrane vesicles (OMVs) are nano-sized structures, which have been recently suggested to play a crucial role in H. pylori pathogenesis. There are growing evidence indicating the relationship of H. pylori infection with extra-gastroduodenal diseases, especially liver-related disorders. This study was aimed to investigate the effects of H. pylori-derived OMVs on autophagy in hepatic stellate cells (HSCs). MATERIAL AND METHODS: A selection of five clinical strains of H. pylori with different virulence genotypes were included. The OMVs were isolated by ultracentrifugation and characterized by scanning electron microscopy (SEM) and dynamic light scattering (DLS). The protein concentration of OMVs was measured by BCA assay. MTT assay was used to determine the viability of LX-2 cells (human HSCs) treated with OMVs. The expression level of MTOR, AKT, PI3K, BECN1, ATG16 and LC3B genes was assessed in OMVs-treated LX-2 cells using quantitative real-time PCR. Moreover, immunocytochemistry was performed to evaluate the protein expression of MTOR and LC3B autophagy markers. RESULTS: H. pylori strains produced round shape nano-vesicles ranging from 50 to 500 nm. Treatment of HSCs with H. pylori-derived OMVs at concentration of 10 µg/mL for 24 h significantly elevated the expression of autophagy inhibitory markers (PI3K, AKT, and MTOR) and suppressed the mRNA expression level of autophagy core proteins (BECN1, ATG16 and LC3B). Immunocytochemistry also presented a substantial reduction in the concentration of LC3B autophagy core protein, and a marked elevation in the amount of MTOR autophagy inhibitory protein. CONCLUSION: This study revealed that H. pylori-derived OMVs could potentially suppress autophagy flux in HSCs as a novel mechanism for H. pylori-mediated liver autophagy impairment and liver disease development. Further studies are required to elucidate the exact role of OMV-carried contents in liver autophagy, and liver-associated disorders.

The possible role of Helicobacter pylori in liver diseases.

According to previous studies, Helicobacter pylori infection is associated with liver disease. In order to better understand the risk of acquiring various liver diseases, we reviewed current knowledge on the impact of H. pylori on the onset, intensification, and progression of various liver diseases caused by the infection of H. pylori. It has been estimated that between 50 and 90% of people worldwide have been infected with H. pylori. The bacterium is mostly responsible for inflamed gastric mucosa, ulcers, and cancers associated with the gastric mucosa. Through the active antioxidant system in H. pylori, the bacteria can neutralize free radicals by synthesizing VacA, a toxin that causes cell damage and apoptosis. Furthermore, there is a possibility that CagA genes may play a role in cancer development. People who have been infected with H. pylori are likely to develop lesions in the skin, the circulation system, and the pancreas. Moreover, transferring blood from the stomach may allow H. pylori to colonize the liver. The bacterium worsened liver function during autoimmune inflammation, toxic injury, chronic HCV infection, chronic HBV infection, and liver cirrhosis. Increasing portal pressure, hyperammonemia, and esophageal varices may be associated with H pylori infection. As a result, it is crucial to diagnose and treat this infection in patients with H. pylori.

The Effects of Helicobacter pylori-Derived Outer Membrane Vesicles on Hepatic Stellate Cell Activation and Liver Fibrosis In Vitro.

Introduction: Helicobacter pylori is a prevalent pathogenic bacterium that resides in the human stomach. Outer membrane vesicles (OMVs) are known as nanosized cargos released by H. pylori, which have been proposed to have a key role in disease progression, pathogenesis, and modulation of the immune system. There are multiple evidences for the role of H. pylori in extragastroduodenal illnesses especially liver-related disorders. However, the precise mechanism of H. pylori extragastroduodenal pathogenesis still remains unclear. In the current study, we aimed to determine the impact of H. pylori-isolated OMVs on hepatic stellate cell (HSC) activation and expression of liver fibrosis markers. Materials and Methods: Five H. pylori clinical strains with different genotype profiles were used. Helicobacter pylori OMVs were isolated using ultracentrifugation and were analyzed by scanning electron microscopy (SEM) and dynamic light scattering (DLS). Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis was applied to determine protein components of H. pylori-derived OMVs. Cell viability of LX-2 human hepatic stellate cell line exposed to OMVs was measured by MTT assay. LX-2 cells were treated with OMVs for 24 h. The gene expression of α-SMA, E-cadherin, vimentin, snail, and ß-catenin was analyzed using quantitative real-time PCR. The protein expression of α-SMA, as a well-studied profibrotic marker, was evaluated with immunocytochemistry. Results: Our results showed that H. pylori strains released round shape nanovesicles ranging from 50 to 500 nm. Totally, 112 various proteins were identified in OMVs by proteomic analysis. The isolated OMVs were negative for both CagA and VacA virulence factors. Treatment of HSCs with H. pylori-derived OMVs significantly increased the expression of fibrosis markers. Conclusions: In conclusion, the present study demonstrated that H. pylori-derived OMVs could promote HSC activation and induce the expression of hepatic fibrosis markers. Further research is required to elucidate the definite role of H. pylori-derived OMVs in liver fibrosis and liver-associated disorders.

Effects of Exosomes Derived From Helicobacter pylori Outer Membrane Vesicle-Infected Hepatocytes on Hepatic Stellate Cell Activation and Liver Fibrosis Induction.

Liver fibrosis is a multifactorial disease with microbial and non-microbial causes. In recent years, Helicobacter pylori infection has been thought to play a critical role in some extra-gastrointestinal manifestations especially liver disorders. Outer membrane vesicles (OMVs) are one of the most important discussed H. pylori virulence factors. In the current study, four different clinical strains of H. pylori were collected and their OMVs were purified using ultra-centrifugation. To investigate their effects on liver cell exosomes, co-incubation with hepatocytes was applied. After a while, hepatocyte-derived exosomes were extracted and incubated with hepatic stellate cells (HSCs) to investigate the HSC activation and fibrosis marker induction. The expression of α-SMA, TIMP-1, ß-catenin, vimentin, and e-cadherin messenger RNAs (mRNA) was assessed using real-time RT-PCR, and the protein expression of α-SMA, TIMP-1, ß-catenin, vimentin, and e-cadherin was evaluated by Western blotting. Our results showed that infected hepatocyte-derived exosomes induced the expression of α-SMA, TIMP-1, ß-catenin, and vimentin in HSCs and e-cadherin gene and protein expression was downregulated. In the current study, we found that H. pylori-derived OMVs may aid the exosome alternation and modified exosomes may have a possible role in HSC activation and liver fibrosis progression.

Prevalence of OXA-type Class D ß-lactamases Among Clinical Isolates of Klebsiella Pneumoniae in Multiple Centers of Tehran, Iran.

BACKGROUND: Drug- and multidrug-resistant Klebsiella pneumoniae isolates have been found worldwide. Treatment failures against carbapenems and extended-spectrum cephalosporins, the currently recommended drugs, contribute to consider K. pneumoniae infections as untreatable infections. The emergence and spread of oxacillinases (OXAs) with carbapenem-hydrolyzing properties are a major concern and seriously become a public health problem worldwide. The present study was aimed to explore the blaOXA genes among clinical isolates of K. pneumoniae in some clinical settings in Tehran, Iran. METHODS: A total of 90 K. pneumoniae isolates were collected from different clinical samples at hospitals in Tehran during the year 2016 and 2018. Antimicrobial susceptibility testing was performed on bacterial isolates using the Kirby-Bauer disc diffusion method on Mueller Hinton agar plates. PCR experiments were carried out to detect the presence of the blaOXA genes, including blaOXA- 1, blaOXA-2, blaOXA-4, blaOXA10, and blaOXA-48-like, using specific primers. RESULTS: The antibiotics susceptibility results showed that 41% of the K. pneumoniae isolates were resistant to imipenem and meropenem. Resistance rates for cephalosporin agents, including cefpodoxime, ceftazidime, cefuroxime, cefotaxime, and cefepime, were measured as 72.3%, 67.8%, 67.7%, 65.5%, and 60%, respectively. In the present study, 51.1% of isolates were classified as multidrug-resistant K. pneumoniae strains. The molecular assays showed that 56.6% of isolates harbored blaOXA-2. In addition, blaOXA-4, blaOXA-1, blaOXA-10, and blaOXA-48-like genes were also found in 16.7%, 5.6%, 1.1%, and 1.1% of isolates, respectively. CONCLUSION: The spread of blaOXAs, especially blaOXA-48-like, among K. pneumoniae isolates indicated the inadequate dissemination control of multidrug-resistant bacteria in the Iranian hospital environment. There is a reason to assume that OXA producing K. pneumoniae will limit clinical therapeutic options in the future and pose threats to national public health among the Iranian population.

Identification of an intestinal microbiota signature associated with hospitalized patients with diarrhea.

As an important global health challenge, diarrhea kills nearly two million people each year. Postinfectious irritable bowel syndrome (IBS) usually manifests itself as the diarrhea-predominant subtype. Small intestinal bacterial overgrowth has been observed more frequently in patients with IBS compared to healthy controls. However, the pathophysiology of IBS is not fully understood, and based on recent evidences, altered gut microbiota is involved in the pathogenesis of IBS. Therefore, we aimed to compare the microbiome in hospitalized patients with diarrhea and healthy individuals. Thirty patients and 10 healthy controls were included into this case-control study. Microbial count was performed using quantitative real-time polymerase chain reaction method using bacterial 16S rRNA gene. Clostridium cluster IV and Bacteroides were significantly more frequent in the patients compared with the healthy individuals (p = 0.02 and 0.023, respectively). However, the quantity of Enterococcus and Bifidobacterium groups were significantly higher in healthy controls than in diarrheal group (p = 0.000076 and 0.001, respectively). The results showed that the number of bacteria in all bacterial groups was significantly different between healthy individuals and diabetic group, whereas the difference between the healthy group and IBS was not significant for Bifidobacterium group. The findings of this study outlined the relationship between diarrhea, IBS, and diabetes disease and bacterial composition. It could be concluded that modifying the bacterial composition by probiotics can be helpful in the control and management of the mentioned disease.