Efflux Pump Inhibitor Phenylalanine-Arginine Β-Naphthylamide Effect on the Minimum Inhibitory Concentration of Imipenem in Acinetobacter baumannii Strains Isolated From Hospitalized Patients in Shahid Motahari Burn Hospital, Tehran, Iran

BACKGROUND

Acinetobacter baumannii has emerged as a highly troublesome pathogen and a leading cause of mortality and morbidity among hospitalized burn patients.

OBJECTIVES

The aims of this study were to determine the frequency of the AdeABC genes and the role of the efflux pump (s) in the imipenem resistance of A. baumannii strains isolated from burn patients.

MATERIALS AND METHODS

This study was conducted on 60 A. baumannii isolates collected from 240 wound samples of burn patients admitted to the Burn Unit of Shahid Motahari Burn hospital, Tehran, Iran. Antibiotic susceptibility tests were performed using the Kirby-Bauer disc diffusion and broth microdilution according to the clinical and laboratory standards institute (CLSI) guidelines. The activity of the efflux pump was evaluated using the efflux pump inhibitor, the phenylalanine-arginine Β-naphthylamide (PAΒN). The AdeABC genes were detected by polymerase chain reaction (PCR) and sequencing.

RESULTS

In this study, 100% of the isolates were resistant to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole, and piperacillin/tazobactam; 56 (94%) to gentamicin; 50 (81%) to amikacin; 58 (97%) to imipenem; and 45 (76%) to tetracycline. Additionally,all the isolates were susceptible to colistin. The susceptibility of the strains to imipenem was highly increased in the presence of the efflux pump inhibitor such that for 58 (96.6%) of the isolates, the PAΒN reduced the minimum inhibitory concentrations (MIC) by 4- to 64-fold. The adeA and adeB genes were detected in 60 (100%) of the isolates, and the adeC gene was present in 51 (85%).

CONCLUSIONS

The efflux pump may play a role in antibiotic resistance in A. baumannii isolates. The ability of A. baumannii isolates to acquire drug resistance by the efflux pump mechanism is a concern. Thus, new strategies are required in order to eliminate the efflux transport activity from resistant A. baumannii isolates causing nosocomial infections.

Anti-proliferative effects of cell wall, cytoplasmic extract of Lactococcus lactis and nisin through down-regulation of cyclin D1 on SW480 colorectal cancer cell line

Background and Objectives:

Colorectal cancer is one of the most types of cancer. Researchers have shown that lactic acid bacteria have antitumor activity. The cell wall of Lactococcus lactis, as the bacterial cytoplasmic extract and nisin can affect the proliferation of cancer cells. Since cyclin D1 plays an important role in the progression of the cell cycle, its regulation can also be a therapeutic approach. We investigated the antiproliferative effect of cell wall, cytoplasmic extract and nisin on SW480 cancer cell line and the expression level of cyclin D1 gene in treated cancer cells.

Materials and Methods:

SW480 cell lines were treated with different concentrations of bacterial cell wall, cytoplasmic extract and nisin. MTT test was also performed. The expression level of cyclin D1 gene was determined using Real time PCR. Data were analyzed using Graph Pad Prism software.

Results:

The growth rate of cancer cells treated with nisin has significantly decreased compared to the cancer cells treated by other two substances (p< 0.05). Survival rates of the cancer cells treated by nisin at a concentration of 2000 μg, cytoplasmic extract, and cell wall were 34%, 47% and 49%, respectively. Real-time PCR results showed that cyclin D1 mRNA expression has significantly decreased in nisin treated sw480 cells (P<0.05).

Conclusion:

The results of this study show that nisin, bacterial cytoplasmic extract, and bacterial cell wall have antiproliferative effects, which are associated with the decreased expression of cyclin D1 in SW480 cell line.

Cross-talk between immune system and microbiota in COVID-19

INTRODUCTION

Human gut microbiota plays a crucial role in providing protective responses against pathogens, particularly by regulating immune system homeostasis. There is a reciprocal interaction between the gut and lung microbiota, called the gut-lung axis (GLA). Any alteration in the gut microbiota or their metabolites can cause immune dysregulation, which can impair the antiviral activity of the immune system against respiratory viruses such as severe acute respiratory syndrome coronavirus (SARS-CoV) and SARS-CoV-2.

AREAS COVERED

This narrative review mainly outlines emerging data on the mechanisms underlying the interactions between the immune system and intestinal microbial dysbiosis, which is caused by an imbalance in the levels of essential metabolites. The authors will also discuss the role of probiotics in restoring the balance of the gut microbiota and modulation of cytokine storm.

EXPERT OPINION

Microbiota-derived signals regulate the immune system and protect different tissues during severe viral respiratory infections. The GLA's equilibration could help manage the mortality and morbidity rates associated with SARS-CoV-2 infection.

In vitro Antibacterial Effect of Hydroalcoholic Extract of Lawsonia inermis, Malva sylvestris, and Boswellia serrata on Aggregatibacter actinomycetemcomitans

Background:

Considering the increased rate of microbial resistance to antibiotics and chemical side effects of antibiotics and antiseptics used for the treatment of periodontal disease, there is a need for an alternative antimicrobial agent with fewer complications. Medicinal herbs have recently become popular as novel antimicrobial agents. This study aimed to assess the antibacterial effects of hydroalcoholic extracts of Lawsonia inermis, Malva sylvestris, and Boswellia serrata on Aggregatibacter actinomycetemcomitans.

Materials and Methods:

Hydroalcoholic extracts of the three medicinal plants were obtained by the maceration technique and A. actinomycetemcomitans was cultured. Antimicrobial efficacy of the three medicinal plants was compared with that of 0.2% chlorhexidine (CHX) according to the Clinical and Laboratory Standards Institute protocol using agar disc diffusion and broth microdilution techniques. All tests were repeated three times.

Results:

Hydroalcoholic extracts of all three plants had antimicrobial activity against A. actinomycetemcomitans. The minimum inhibitory concentration (MIC) of L. inermis, M. sylvestris, and B. serrata was 78.1, 156.2, and 1666 μg/mL with no significant difference between them. The MIC of CHX was 3.33 μg/mL, which was significantly higher than that of B. serrata extract.

Conclusion:

Given that further in vivo studies confirm other properties of these extracts and their safety in terms of cytotoxicity and mutagenicity, hydroalcoholic extracts of L. inermis and M. sylvestris may be used in mouthwashes or local delivery systems to affect periodontal biofilm.

Prevalence, serotyping and drug susceptibility patterns of Escherichia coli isolates from kidney transplanted patients with urinary tract infections

BACKGROUND

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) are among the main pathogens in urinary tract infections (UTIs) among kidney transplant patients (KTPs).

AIM

To estimate the prevalence of ESBL-producing E. coli in KTPs and to evaluate the most prevalent serotypes and antibacterial susceptibility patterns of isolated bacteria in Tehran, Iran.

METHODS

A total of 60 clinical isolates of uropathogenic E. coli were collected from 3 kidney transplant centers from April to May 2019. Antimicrobial susceptibility testing was performed by the disk diffusion method as recommended by the Clinical Laboratory and Standards Institute. The serotyping of E. coli isolates was performed by the slide agglutination method. The presence of bla_TEM, bla_SHV, and bla_CTX-M genes was evaluated by polymerase chain reaction.

RESULTS

The frequency of ESBL-producing E. coli in KTPs was found to be 33.4%. All of the 60 E. coli isolates were found to be susceptible to doripenem (100%) and ertapenem (100%). High resistance rates to ampicillin (86%), cefotaxime (80%), and cefazolin (77%) were also documented. The most frequent serotypes were serotype I (50%), serotype II (15%), serotype III (25%), and serotype VI (10%). The gene most frequently found was bla_TEM (55%), followed by bla_CTX-M (51%) and bla_SHV (41%).

CONCLUSION

Molecular analysis showed that bla_TEM was the most common ESBL-encoding gene. The high resistance to β-lactams antibiotics (i.e., ampicillin, cefotaxime, and cefazolin) found in E. coli from KTPs with UTIs remains a serious clinical challenge. Further efforts to control ESBL-producing E. coli should include the careful use of all antibiotics as well as barrier precautions to reduce spread.

Phenotypic Investigation of the Antimicrobial Effect of Organic and Hydro-Alcoholic Extracts of Boswellia serrata on Oral Microbiota

Objectives:

Considering the emergence of resistant microbes and side effects of chemical drugs, in this study, the inhibitory effect of organic and hydro-alcoholic extracts of Boswellia serrata (B. serrata) on some oral microbiota was investigated.

Materials and Methods:

In this experimental study, standard strains of Candida albicans (C. albicans; PTCC 5027), Candida glabrata (C. glabrata; PTCC 5295), Candida krusei (C. krusei; PTCC 5297), and Streptococcus mutans (S. mutans; PTCC 1688) were collected from the Iranian Research Organization for Science and Technology (IROST). Then, the minimum inhibitory concentration (MIC) of organic and hydro-alcoholic extracts of B. serrata was determined based on the CLSI protocol and using the micro-dilution method. The contents of each well were subcultured in Müller-Hinton agar (Candida species) and blood agar (S. mutans). The lowest concentration with no growth was considered as the minimum fungicidal concentration (MFC) or bactericidal concentration (MBC). Statistical analyses were performed using Mann-Whitney test.

Results:

Hydro-alcoholic extract of B. serrata at the concentration of 50 mg/ml inhibited the growth of C. albicans and S. mutans. It also inhibited the growth of C. krusei and C. glabrata at the concentration of 100 mg/ml. Organic extract of B. serrata at the concentration of 200 mg/ml only inhibited the growth of C. glabrata.

Conclusion:

Hydro-alcoholic extract of B. serrata had a greater inhibitory effect on C. albicans and S. mutans compared to the organic extract.

Rifampin resistance among individuals with extrapulmonary tuberculosis: 4 years of experience from a reference laboratory

Information is limited about the drug resistance patterns in extrapulmonary tuberculosis (EPTB) in Iran. This study aimed to determine the prevalence of EPTB and to investigate the drug-resistance pattern in Mycobacterium tuberculosis strains collected from extrapulmonary samples at the Tehran regional TB reference laboratory. Extrapulmonary specimens from individuals with suspected TB referred to the TB reference laboratories in five cities of Iran were collected. Both standard conventional methods (culture and direct smear microscopy) and Xpert MTB/RIF assay were used for the identification of mycobacteria. Drug susceptibility testing was done using Xpert MTB/RIF. The proportion method on Lowenstein–Jensen medium was performed for confirmation. Between 2016 and 2020, a total of 12 050 clinical specimens from individuals with suspected TB were collected, of which 10 380 (86%) were pulmonary specimens and 1670 (14%) were extrapulmonary. Of the extrapulmonary specimens, 85 (5.0%) were positive for M. tuberculosis, and the remaining 1585 (95.0%) samples were negative by standard methods. Of 85 M. tuberculosis isolates, drug susceptibility testing was performed for 32 isolates, of which 1 (3.1%, 95% CI 0.0%–9.4%) was rifampin resistant and 31 (96.9%, 95% CI 90.1%–100%) were pan-susceptible. The rifampin-resistant isolate was also resistant to isoniazid, so was assigned as a multidrug-resistant TB. Our study indicated the frequency of drug-resistance among EPTB in Iran. Establishing rapid diagnostic methods for detection of drug-resistance in EPTB, performing drug susceptibility testing for all EPTB cases to provide effective treatment, and continuous monitoring of drug resistance, are suggested for prevention and control of drug resistance in EPTB in Iran.

89 Antimicrobial Resistance Pattern and Prevalence of Extended Spectrum Beta-lactamase in Non-fermenting Gram Negative Bacteria, Isolated from Burn Wounds: A Prospective Study from a Tertiary Burn Center

Introduction

Burn wound infections are one of the major causes for long-term hospitalization and mortality among patients with thermal injuries. Identifying the bacterial cause of infection and determining the appropriate antibiotic to treat these infections is an important stage in treatment. The aim of this study was to investigate antimicrobial drug resistance in non-fermenting gram-negative bacteria isolated from burn wounds in patients who were admitted to a tertiary burn center.

Methods

In this prospective study during a six-month period in 2018,100 isolates of non-fermenting gram-negative bacteria were collected from 100 patients with thermal injuries. Antibiotic susceptibility test was performed using the Kirby-Bauer method based on the clinical and laboratory standards institute guidelines. Double-disc synergy test, a phenotypic method, was used to identify strains producing extended-spectrum beta-lactamase (ESBL). Data analyses were performed using SPSS.

Results

A total of 100 wound samples were examined from 100 patients, 76% were male and 24% were female with a mean age of 33 years (range 1–89 years old). Mean total body surface area burned was 35% (range 1–95%) and mean length of hospital stay was 24 days (range 3–69 days). Eighty five percent of cases were under 50 years old. Overall mortality rate in this study was 17%. The major causes of burn were liquefied natural gas tank explosion (35%) and scalds (19%). Acinetobacter baumannii (A.baumannii) was the most common pathogen followed by Pseudomonas aeruginosa (P.aeruginosa) (60% and 40%, respectively). ESBL producing rate was significantly higher in P.aeruginosa isolates (27.5%) than A.baumannii isolates (3.3%) (P-value &lt; 0.001). Antibiotic resistance pattern of P.aeruginosa showed the highest resistance to ciprofloxacin, amikacin and imipenem (95%), followed by gentamicin (92.9%),ceftazidime(87.50) and piperacillin-tazobactam(85%). Antibiotic resistance pattern of A.baumannii showed the highest resistance to ceftazidime(100%) followed by ciprofloxacin, amikacin, imipenem(98.3%), gentamicin and piperacillin-tazobactam (93.3%). Multiple drug resistance (MDR) rate among A.baumannii and P.aeruginosa was 98.3% and 92.5% respectively, which is higher than previous reports.

Conclusions

A.baumannii and P.aeruginosa were the most common pathogens identified in this cohort with a significant MDR rate (over 95%). New strategies to control expansion of antimicrobial resistance in burn centers are necessary.

Applicability of Research to Practice

This study shows the antimicrobial resistance pattern and prevalence of ESBL in burn wounds indicating that further studies requires to identify new strategies to control emerging antimicrobial resistance in burn centers.

In silico and In vitro Assessment of Antibacterial Activity, LPS Binding Affinity, and Toxicity of the GKY25 Peptide

INTRODUCTION

Extensively and multi-drug resistant isolates of bacteria (MDR, XDR) have caused significant health problems and are responsible for high morbidity and mortality as well. In this critical condition, the discovery, design, or development of new antibiotics is of great concern. According to this necessity, antimicrobial peptides (AMPs) suggested as promising agents. Accordingly, this study aims to evaluate the GKY25 peptide to develop its future antibacterial applications as well as confirmation of LPS neutralization.

METHODS

Predictions of 3D structure and helical wheel projection analysis of the peptide were performed by ITASSER and Heliquest servers. Binding affinity and antibacterial activity were performed using molecular docking and CAMPR4, respectively, followed by experimental binding assay as well as in vitro antibacterial assay.

RESULTS

GKY25 was predicted as an alpha-helical peptide, and its helicity showed probable projection of hydrophobic and positively-charged amino acid residues. Docking studies showed binding affinity of GKY25 peptide to gram-positive and outer and inner gram-negative bacterial membranes as -5.7, -6.8, and -4 kcal/mole, respectively. CAMPR4 analysis predicted the peptide as an AMP. Experimental binding assay showed that the peptide binds LPS immediately and their interaction was observed at 274 nm.

CONCLUSION

Gathering all in silico and in vitro data together, GKY25 is a good drug lead that could be examined further using clinical isolates of gram-negative bacteria in vitro.

Search for Proteins in the Liquid Extract of Edible Mushroom, Agaricusbisporus, and Studying their Antibacterial Effects

The edible mushrooms (basidomycetes) have high nutritional value, promote the immune system, and as a source of natural antimicrobial substances have been used to cure bacterial infections since ancient times.Various kinds of proteins with several biological activities are produced by mushrooms. In this research, in order to evaluate antibacterial activity of edible mushrooms, we isolated proteins of Agaricus bisporus and examined their effects on gr + and gr- bacteria. Protein extract of the mushroom was first discriminated by homogenation of the chopped fruiting bodies in tris buffer with pH 7.3 and then centrifuged. The Protein concentration was determined by Bradford method. Gel filtration of the proteins was performed by Sephadex G-100 using UV spectrophotometer as detector.Three fractions were collected and their purity level were defined by SDS-PAGE . In order to reach to a more purification level, isolated proteins from the G-100 column were fractionated by the DEAE ion exchange column. Antibacterial activity of total extact proteins as well as protein fractions was evaluated by the method of microdilution against gr+ and gr- bacteria. This study showed that the isolated proteins from the mushroom, Agaricus bisporus fruiting bodies were effective against Staphylococcus aureus and MRSA. The proteins of edible mushrooms like Agaricus bisporus, maybe viewed as a natural source of antibacterial agents.

Antibacterial and antifungal activities of the endemic species Glaucium vitellinum Boiss. and Buhse

OBJECTIVES

Belonging to Papaveraceae family, Glaucium vitellinum is one of the Persian endemic plants which has not been investigated biologically. The present paper focused on the assessment of the antibacterial and antifungal activities of the total methanol extract and alkaloid sub-fraction of the flowering aerial parts of G. vitellinum.

MATERIALS AND METHODS

The antibacterial and antifungal activities were investigated using cup plate method and disc diffusion assay, respectively. The MIC values of the active samples were determined using micro plate dilution method.

RESULTS

The crude extract and alkaloid sub-fraction of G. vitellinum had significant inhibition activity on the growth of S. aureus and S. typhi. From antifungal assay, it is concluded that only the yeast C. albicans, showed a high sensitivity to the extract and especially to the related alkaloid sub-fraction.

CONCLUSIONS

Regarding the results, G. vitellinum could be employed as a natural antibacterial and antifungal agent against S. aureus, S. typhi, and C. albicans, respectively. Moreover, based on the results of this study, further in vivo and ex vivo confirmatory tests for total methanol extract and alkaloid sub-fraction are recommended.

Investigating the validity of mCIM and sCIM phenotypic methods in screening Pseudomonas aeruginosa isolates producing IMP, VIM, and NDM metallo-beta-lactamases isolated from burn wounds

Metallo-beta-lactamase-producing Pseudomonas aeruginosa (P. aeruginosa) is a major pathogen in burn wounds, often exhibiting high levels of antibiotic resistance, which complicates treatment strategies. This study deals with the validity of the modified Carbapenem Inactivation Method (mCIM) and the simplified Carbapenem Inactivation Method (sCIM) phenotypic tests for screening metallo-beta-lactamase (MBL) production by P. aeruginosa isolates from a referral burn center in Iran. Forty isolates were obtained between January and June 2021 and identified using conventional biochemical methods. Antimicrobial susceptibility testing was conducted following Clinical and Laboratory Standards Institute (CLSI) 2021 guidelines. mCIM based on CLSI 2023 guidelines was used to detect carbapenemase production. sCIM was also used based on previously developed protocols. PCR was performed to detect blaIMP, blaVIM, and blaNDM genes. The results were analyzed using SPSS and MedCalc. We observed a 90% resistance rate to imipenem and high resistance to other antibiotics, with multidrug-resistant (MDR) strains constituting 95% of the isolates. The mCIM test demonstrated high sensitivity (87.50%) and high negative predictive value (89.47%) and moderate specificity (70.83%) and moderate positive predictive value (66.67%) for detecting MBLs. In contrast, the sCIM test was unreliable, indicating a need for more standardized testing protocols. This study underscores the importance of accurate and timely detection of carbapenemase production to guide effective treatment.

Role of Aders and OXA23 Genes among Imipenem Resistant Acinetobacter baumannii Isolates from Two Hospitals of Tehran, Iran

BACKGROUND

This study aimed to evaluate the role of efflux pump regulator and OXA-23 genes in imipenem resistance Acinetobacter baumannii strains isolated from hospitalized patients in Tehran, Iran.

METHODS

This study was conducted on 60 A. baumannii isolates collected from patients admitted to the Shahid Motahari and Taleghani Hospitals in Tehran during 2013-14. Antibiotic susceptibility tests (AST) and minimal inhibitory concentration (MIC) was determined by broth micro dilution methods according to CLSI 2014 guidelines. The frequency of efflux pump adeRS and OXA-23 genes were detected by PCR and further sequencing.

RESULTS

The resistance of A. baumannii isolates to tested antibiotics was 100% to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole and piperacillin/tazobactam, 97% to imipenem, 94% to gentamicin, 83% to amikacin, 76% to tetracycline, and 0.0% to colistin. The MIC of 58 (96.6%) strains to imipenem was highly decreased in the presence of efflux pump inhibitor (PaβN), by 4 to 64 folds. The adeR and adeS genes were detected in 36 (60%) and 59 (98.3%), respectively and the frequency of OXA-23 gene was 57 (95%) of isolates.

CONCLUSION

Existence of adeRS and OXA-23 genes in more than 50% of A. baumannii isolates in this study shows the presumptive role of efflux pump in simultaneous of carbapenemase production. Therefore, using new strategies are required in order to stop the vertical or horizontal exchanges mentioned genes from the resistant A. baumannii isolates to sensitive strains.

Blood culture and antimicrobial susceptibility pattern of bacteria and fungi isolated from febrile neutropenic patients treated with chemotherapy at Taleghani hospital, Tehran

BACKGROUND AND OBJECTIVES

The aim of this study was to determine the drug susceptibility pattern of the pathogens causing bacteraemia and fungemia in patients who have developed febrile neutropenia after chemotherapy.

MATERIALS AND METHODS

A total of 95 patients with suspected or proven malignancy (50 patients) were admitted to the adult haematology ward at Taleghani Hospital in Tehran. Blood samples were inoculated into the bottles of Bact/Alert blood culture system and sent to Payvand's clinical and special laboratory immediately and then incubated at 35 ± 2°C. Culture from positive bottles were plated on appropriate media and incubated at 37°C and 30°C for bacterial and fungal isolation, respectively. A bacterial suspension with turbidity equal to 0.5 McFarland (1.5 × 10⁸ CFU/mL) was prepared and used for the Vitec2 system (biomerioux). Statistical analysis using independent Fisher's exact test was conducted and a p-value of < 0.05 was considered as significant.

RESULTS

Among 50 patients with approved malignancy, Acute Lymphoblastic Leukaemia (ALL) and Acute Myeloid Leukaemia (AML) were the most common underlying diseases. This study showed, 20% (n: 10) of febrile neutropenic episodes established positive blood culture. Of them, 3 were Gram-negative (30%) and 5 were-Gram-positive bacteria (50%) and 2 patients (20%) showed fungemia with Fusarium spp.

CONCLUSION

It is crucial to know about the likely pathogens and their local antibiotic and antifungal sensitivity patterns. Such local findings will show if any modifications to treatment guidelines are necessary.

The effect of Helicobacter pylori-derived extracellular vesicles on glucose metabolism and induction of insulin resistance in HepG2 cells

Helicobacter pylori infection has been associated with the development of insulin resistance (IR). This study aimed to examine the effect of H. pylori-derived extracellular vesicles (EVs) on IR induction. EVs were derived from two H. pylori strains, and characterised by transmission electron microscopy and dynamic light scattering. Different concentrations of insulin were added to HepG2 cells to induce IR model. HepG2 cells were exposed to various concentrations of H. pylori-derived EVs to assess IR development. The gene expression of IRS1, AKT2, GLUT2, IL-6, SOCS3, c-Jun and miR-140 was examined using RT-qPCR. Glucose uptake analysis revealed insulin at 5 × 10 -7 mol/l and EVs at 50 µg/ml induced IR model in HepG2 cells. H. pylori-derived EVs downregulated the expression level of IRS1, AKT2, and GLUT2, and upregulated IL-6, SOCS3, c-Jun, and miR-140 expression in HepG2 cells. In conclusion, our findings propose a novel mechanism by which H. pylori-derived EVs could potentially induce IR.

Expression analysis of miRNA-155 level in Helicobacter pylori related inflammation and chronic gastritis

Background and Objectives

Helicobacter pylori, is a major etiologic agent associated with gastritis. There is more evidence of noncoding microRNAs (miRs) dysregulation in gastrointestinal diseases, including inflammation caused by Helicobacter pylori. Also, the classification of gastrointestinal malignancies using the miRs profile is better than the protein profile. MiRNA-155(miRNA-155) among other miRs plays an important role in control of inflammation and gastric malignancy, so it can be remarkable prognosis marker of gastric cancer in the phase of chronic gastritis. The aim of this study was to compare the expression of miRNA-155 in gastric biopsy and serum samples of adult patients with chronic gastritis.

Materials and Methods

Biopsy and blood samples were collected from endoscopy candidates at Taleghani hospital, Tehran, during 2019. H. pylori infection was detected using histology, culture and molecular PCR methods. Based on cagA and vacA genotyping, the toxicity of H. pylori isolates were determined. After RNA extraction, the expression rate of miRNA-155 was evaluated by real-time polymerase chain reaction (RT-PCR) in gastric tissue and serum of adults infected by H. pylori (n = 30) compared with control group without infection (n = 20). RNU6 housekeeping miRNA were used as endogenous control and statistical analyses were performed using SPSS, ANOVA and Student's t-test.

Results

miRNA-155 expression in H. pylori infected adult patients increased significantly by 5.61 and 10.11 fold in serum and tissue respectively, compared to that observed in the control group. Evaluation of miRNA-155 expression pattern in relation to bacterial virulence factors showed that the increase in miRNA-155 expression is independent of CagA and VacA toxins.

Conclusion

According to the differential expression patterns of miRNA-155 in serum samples of the infected adult patients, miRNA-155 has the potential to evaluate as chronic gastritis marker.

The modulatory effect of Lactobacillus gasseri ATCC 33323 on autophagy induced by extracellular vesicles of Helicobacter pylori in gastric epithelial cells in vitro

Helicobacter pylori has been recognized as a true pathogen, which is associated with various gastroduodenal diseases, and gastric adenocarcinoma. The crosstalk between H. pylori virulence factors and host autophagy remains challenging. H. pylori can produce extracellular vesicles (EVs) that contribute to gastric inflammation and malignancy. Some probiotic strains have been documented to modulate cell autophagy process. This study was aimed to investigate the modulatory effect of cell-free supernatant (CFS) obtained from Lactobacillus gasseri ATCC 33323 on autophagy induced by H. pylori-derived EVs. EVs were isolated from two clinical H. pylori strains (BY-1 and OC824), and characterized using transmission electron microscopy (TEM) and dynamic light scattering (DLS). The viability of AGS cells was assessed after exposure to different concentrations of H. pylori EVs, and L. gasseri CFS. Based on MTT assay and Annexin V-FITC/PI staining, 50 μg/ml of H. pylori EVs and 10 % v/v of L. gasseri CFS were used for further cell treatment experiments. Autophagy was examined using acridin orange (AO) staining, RT-qPCR analysis for autophagy mediators (LC3B, ATG5, ATG12, ATG16L1, BECN1, MTOR, and NOD1), and western blotting for LC3B expression. H. pylori EVs were detected to range in size from 50 to 200 nm. EVs of both H. pylori strains and L. gasseri CFS showed no significant effect on cell viability as compared to untreated cells. H. pylori EVs promoted the development of acidic vesicular organelles and the expression of autophagy-related genes (LC3B, ATG5, ATG12, ATG16L1, BECN1, and NOD1), and decreased the expression of MTOR in AGS cells at 12 and 24 h time periods. In addition, the production of LC3B was increased following 12 h of treatment in AGS cells. In contrast, L. gasseri CFS effectively inhibited EVs-induced autophagy, as evidenced by reduced acidic vesicular organelle formation and modulation of autophagy markers. Our study indicated that L. gasseri CFS can effectively suppress H. pylori EV-induced autophagy in AGS cells. Further investigations are required to decipher the mechanism of action L. gasseri CFS and its metabolites on autophagy inhibition induced by H. pylori.