Apparent intracellular Helicobacter pylori detected by immunohistochemistry - the missing link in eradication failure

LOX-1 acts as an N6-methyladenosine-regulated receptor for Helicobacter pylori by binding to the bacterial catalase

The role of N6-methyladenosine (m6A) modification of host mRNA during bacterial infection is unclear. Here, we show that Helicobacter pylori infection upregulates host m6A methylases and increases m6A levels in gastric epithelial cells. Reducing m6A methylase activity via hemizygotic deletion of methylase-encoding gene Mettl3 in mice, or via small interfering RNAs targeting m6A methylases, enhances H. pylori colonization. We identify LOX-1 mRNA as a key m6A-regulated target during H. pylori infection. m6A modification destabilizes LOX-1 mRNA and reduces LOX-1 protein levels. LOX-1 acts as a membrane receptor for H. pylori catalase and contributes to bacterial adhesion. Pharmacological inhibition of LOX-1, or genetic ablation of Lox-1, reduces H. pylori colonization. Moreover, deletion of the bacterial catalase gene decreases adhesion of H. pylori to human gastric sections. Our results indicate that m6A modification of host LOX-1 mRNA contributes to protection against H. pylori infection by downregulating LOX-1 and thus reducing H. pylori adhesion.

[Mechanisms of Helicobacter pylori Intracellular Infection and Reflections Concerning Clinical Practice]

Helicobacter pylori (H. pylori), for a long time, has generally been considered an extracellular bacterium. However, recent findings have shown that H. pylori can gain entry into host cells, evade attacks from the host immune system and the killing ability of medication, form stable intracellular ecological niche, and achieve re-release into the extracellular environment, thus causing recurrent infections. H. pylori intracellular infection causes cellular signaling and metabolic alterations, which may be closely associated with the pathogenesis and progression of tumors, thereby presenting new challenges for clinical eradicative treatment of H. pylori. Herein, examining this issue from a clinical perspective, we reviewed reported findings on the mechanisms of how H. pylori achieved intracellular infection, including the breaching of the host cell biological barrier, immune evasion, and resistance to autophagy. In addition, we discussed our reflections and the prospects of important questions concerning H. pylori, including the clinical prevention and control strategy, intracellular derivation, and the damage to host cells.

Treatment of refractory Helicobacter pylori infection: A new challenge for clinicians

Patients who have failed two or more attempts to eradicate Helicobacter pylori are commonly referred to as refractory. Although the incidence of refractory Helicobacter pylori infection is only 10–20%, with the increasing rate of antibiotic resistance in various regions, the treatment of refractory Helicobacter pylori infection has gradually become a difficult problem faced by clinicians. When choosing a rescue therapy, the physician must consider numerous factors. A longer treatment duration, higher doses of proton pump inhibitors (PPIs), or the use of potassium-competitive acid blocker (P-CAB) may increase the efficacy of triple therapy or bismuth quadruple therapy. Rescue treatment based on bismuth quadruple therapy usually achieves better results. At the same time, treatment based on drug susceptibility tests or genotypic resistance is recommended where available. Of course, appropriate empiric treatment can also be selected according to local drug resistance, a patient’s previous medication history and compliance. It is the best choice if it can improve the success rate of the first treatment and reduce the occurrence of refractory Helicobacter pylori infection. This review aims to summarize the articles related to refractory Helicobacter pylori in recent years and to explore a better remedial treatment plan for clinicians.

Polio returns to the USA: An epidemiological alert

On July 21, 2022, the USA witnessed the first case of poliomyelitis after 3 decades of its eradication. Poliomyelitis is a crippling disease that results from infection with any one of the three related poliovirus types (referred to as types P1, P2, and P3), members of the enterovirus (picornavirus) family. The New York State Department of Health confirmed that a case of paralytic poliomyelitis was reported from a 20-year-old Hungarian traveller residing in Rockland County. The detected viral sequence has been found to have vaccine-derived poliovirus type 2 (VDPV2) suggesting an origin from the live attenuated oral polio vaccine (OPV). Since immunisation remains the only preventable measure, this article explores suggestions from the Centers for Disease Control and Prevention on reliable Inactivated (killed) polio vaccination in high-risk patients along with early case detection and treatment. In light of the above-mentioned findings, this research further details future recommendations like cessation of the OPV, encouragement of inactivated polio vaccine (IPV) in vaccination schedules, sensitive epidemiological surveillance system and appropriate training for healthcare providers. The affected countries have been further advised to have effective outbreak response strategy plans in place so that they can respond and stay prepared for such outbreaks in the future.

Host Cell Antimicrobial Responses against Helicobacter pylori Infection: From Biological Aspects to Therapeutic Strategies

The colonization of Helicobacter pylori (H. pylori) in human gastric mucosa is highly associated with the occurrence of gastritis, peptic ulcer, and gastric cancer. Antibiotics, including amoxicillin, clarithromycin, furazolidone, levofloxacin, metronidazole, and tetracycline, are commonly used and considered the major treatment regimens for H. pylori eradication, which is, however, becoming less effective by the increasing prevalence of H pylori resistance. Thus, it is urgent to understand the molecular mechanisms of H. pylori pathogenesis and develop alternative therapeutic strategies. In this review, we focus on the virulence factors for H. pylori colonization and survival within host gastric mucosa and the host antimicrobial responses against H. pylori infection. Moreover, we describe the current treatments for H. pylori eradication and provide some insights into new therapeutic strategies for H. pylori infection.

Comparison of special stains (Giemsa stain and Modified Toluidine Blue stain) with immunohistochemistry as gold standard for the detection of H. pylori in gastric biopsies

BACKGROUND AND STUDY AIMS

Helicobacter pylori (H. pylori) has been extensively implicated in the etiology and pathogenesis of gastric ulcers and carcinomas, which has necessitated its efficient and cost-effective identification in gastric biopsy samples. We have sought to compare various staining methods, namely, Hematoxylin and Eosin (H&E), Giemsa, and Modified Toluidine Blue (MTB), with immunohistochemistry (IHC; gold standard) in terms of efficacy, staining costs, and duration of performing the stains in settings with limited resources.

PATIENTS AND METHODS

Gastric biopsy specimens of 50 patients who presented with gastritis symptoms were stained with H&E, Giemsa, MTB, and IHC. The sensitivity, specificity, positive/negative predictive values, and the receiver operating characteristic curve were calculated for each stain.

RESULTS

In all, 32 cases of 50 were positive for H. pylori on IHC. The specificity for both H&E and Giemsa was 88.8%, whereas it was lower for MTB (83.3%). The sensitivity of H&E was much lower (46.8%) compared with the other stains (90.6% Giemsa, 93.7% MTB). The most inexpensive and time-consuming stain was H&E followed by MTB and Giemsa.

CONCLUSION

When H&E is used alone for H. pylori detection, a significant number of cases may be overlooked, especially mild inflammatory cases and when coccoid forms of the bacteria are present. This study proposes the use of either Giemsa or MTB as reliable alternatives for IHC in resource-limited settings to combat the high prevalence of H. pylori in the developing world.

Improving the ability of antimicrobial susceptibility tests to predict clinical outcome accurately: Adding metabolic evasion to the equation

Antimicrobial susceptibility tests (AST) are based on the minimal inhibitory concentration (MIC), the method used worldwide to guide antimicrobial therapy. Despite its relevance in correctly predicting clinical outcome for most acute infections, this approach is misleading for multiple clinical cases in which pathogens do not grow rapidly, uniformly or with physical protection. This behaviour, named 'metabolic evasion' (ME), enables bacteria to survive antimicrobials. ME can result from different, and sometimes combined, bacterial mechanisms such as biofilms, intracellular growth, persisters or dormancy. We discuss how ME can influence the MIC-based probability of target attainment. We identify clinical cases in which this approach is undermined by ME and propose a new approach that takes ME into account in order to improve patient management and the evaluation of innovative drugs.

Ethnicity and clinical outcomes in COVID-19: A systematic review and meta-analysis

BACKGROUND

Patients from ethnic minority groups are disproportionately affected by Coronavirus disease (COVID-19). We performed a systematic review and meta-analysis to explore the relationship between ethnicity and clinical outcomes in COVID-19.

METHODS

Databases (MEDLINE, EMBASE, PROSPERO, Cochrane library and MedRxiv) were searched up to 31st August 2020, for studies reporting COVID-19 data disaggregated by ethnicity. Outcomes were: risk of infection; intensive therapy unit (ITU) admission and death. PROSPERO ID: 180654.

FINDINGS

18,728,893 patients from 50 studies were included; 26 were peer-reviewed; 42 were from the United States of America and 8 from the United Kingdom. Individuals from Black and Asian ethnicities had a higher risk of COVID-19 infection compared to White individuals. This was consistent in both the main analysis (pooled adjusted RR for Black: 2.02, 95% CI 1.67-2.44; pooled adjusted RR for Asian: 1.50, 95% CI 1.24-1.83) and sensitivity analyses examining peer-reviewed studies only (pooled adjusted RR for Black: 1.85, 95%CI: 1.46-2.35; pooled adjusted RR for Asian: 1.51, 95% CI 1.22-1.88). Individuals of Asian ethnicity may also be at higher risk of ITU admission (pooled adjusted RR 1.97 95% CI 1.34-2.89) (but no studies had yet been peer-reviewed) and death (pooled adjusted RR/HR 1.22 [0.99-1.50]).

INTERPRETATION

Individuals of Black and Asian ethnicity are at increased risk of COVID-19 infection compared to White individuals; Asians may be at higher risk of ITU admission and death. These findings are of critical public health importance in informing interventions to reduce morbidity and mortality amongst ethnic minority groups.