Pepsinogen II in gastritis and Helicobacter pylori infection

Generation and characterization of nanobodies targeting human pepsinogens

Human pepsinogens (mainly pepsinogen I and pepsinogen II) are the major inactive precursor forms of the digestive enzyme pepsin which play a crucial role in protein digestion. The levels and ratios of human pepsinogens have demonstrated potential as diagnostic biomarkers for gastrointestinal diseases, particularly gastric cancer. Nanobodies are promising tools for the treatment and diagnosis of diseases, owing to their unique recognition properties. In this study, recombinant human pepsinogens proteins were expressed and purified as immunized antigens. We constructed a VHH phage library and identified several nanobodies via phage display bio-panning. We determined the binding potency and cross-reactivity of these nanobodies. Our study provides technical support for developing immunodiagnostic reagents targeting human pepsinogens.

RE.GA.IN.: the Real-world Gastritis Initiative-updating the updates

At the end of the last century, a far-sighted 'working party' held in Sydney, Australia addressed the clinicopathological issues related to gastric inflammatory diseases. A few years later, an international conference held in Houston, Texas, USA critically updated the seminal Sydney classification. In line with these initiatives, Kyoto Global Consensus Report, flanked by the Maastricht-Florence conferences, added new clinical evidence to the gastritis clinicopathological puzzle.The most relevant topics related to the gastric inflammatory diseases have been addressed by the Real-world Gastritis Initiative (RE.GA.IN.), from disease definitions to the clinical diagnosis and prognosis. This paper reports the conclusions of the RE.GA.IN. consensus process, which culminated in Venice in November 2022 after more than 8 months of intense global scientific deliberations. A forum of gastritis scholars from five continents participated in the multidisciplinary RE.GA.IN. consensus. After lively debates on the most controversial aspects of the gastritis spectrum, the RE.GA.IN. Faculty amalgamated complementary knowledge to distil patient-centred, evidence-based statements to assist health professionals in their real-world clinical practice. The sections of this report focus on: the epidemiology of gastritis; Helicobacter pylori as dominant aetiology of environmental gastritis and as the most important determinant of the gastric oncogenetic field; the evolving knowledge on gastric autoimmunity; the clinicopathological relevance of gastric microbiota; the new diagnostic horizons of endoscopy; and the clinical priority of histologically reporting gastritis in terms of staging. The ultimate goal of RE.GA.IN. was and remains the promotion of further improvement in the clinical management of patients with gastritis.

The role of gastrin 17 and pepsinogen I:pepsinogen II ratio in pathological diagnosis and endoscopic selection in gastritis patients

BACKGROUND

The noninvasive serum markers pepsinogen I (PGI), pepsinogen II (PGII), gastrin-17 (G17), and PGI:PGII ratio (PGR) have recently been proposed as a new tool for predicting various gastric pathologies.

METHODS

A total of 83 gastritis patients confirmed by gastroscopy were enrolled, with 78 undergoing concurrent colonoscopies. The control group included 99 healthy subjects. Enzyme-linked immunosorbent assay was used to detect PGI, PGII, G17, and PGR. The performance of serological analysis for detecting gastritis pathology was evaluated using receiver operating characteristic (ROC) curves.

RESULTS

The G17 and PGII levels increased significantly (P < .001), whereas PGR levels decreased (P = .001) in the gastritis group. The ROC analysis revealed that PGR had a sensitivity and specificity of 70.83% and 86.67%, respectively, in predicting Helicobacter pylori-infected gastritis and a sensitivity and specificity of 88% and 65.52%, respectively, in predicting active gastritis. The G17 levels were significantly elevated in gastritis patients undergoing concurrent colonoscopies (P < .05).

CONCLUSION

Pepsinogen I:pepsinogen II ratio was found to be a useful predictor of active gastritis and H pylori-infected gastritis. Furthermore, G17 was found to be closely related to pathological conditions found by colonoscopy and may provide recommendations for whether gastritis patients should undergo a concurrent colonoscopy.

Helicobacter pylori-associated Chronic Atrophic Gastritis and Progression of Gastric Carcinogenesis

Chronic inflammation due to a Helicobacter pylori (H. pylori) infection is a representative cause of gastric cancer that can promote gastric carcinogenesis by abnormally activating immune cells and increasing the inflammatory cytokines levels. H. pylori infections directly cause DNA double-strand breaks in gastric epithelial cells and genetic damage by increasing the enzymatic activity of cytidine deaminase. Eventually, gastric cancer is induced through dysplasia. Hypermethylation of tumor suppressor genes is an important cause of gastric cancer because of a H. pylori infection. In addition, the changes in gastric microbiota and the mucosal inflammatory changes associated with a co-infection with the Epstein-Barr virus are associated with gastric cancer development. DNA damage induced by H. pylori and the subsequent responses of gastric stem cells have implications for gastric carcinogenesis. Although the pathogenesis of H. pylori has been established, many uncertainties remain, requiring more study.

Clinical value of serum pepsinogen in the diagnosis and treatment of gastric diseases

Pepsinogen, secreted from the gastric mucosa, is the precursor of pepsin. It is categorized as pepsinogen 1 and pepsinogen 2 based on its immunogenicity. The pepsinogen content that can enter the blood circulation through the capillaries of the gastric mucosa is approximately 1% and remains stable all the time. The pepsinogen content in serum will change with the pathological changes of gastric mucosa. Therefore, the level of pepsinogen in serum can play a role in serologic biopsy to reflect the function and morphology of different regions of gastric mucosa and serve as an indicator of gastric disease. This study conducts relevant research on serum pepsinogen 1, pepsinogen 2, and the ratio of pepsinogen 1 to pepsinogen 2, and reviews their important value in clinical diagnosis of Helicobacter pylori infection, gastric ulcer, and even gastric carcinoma, providing ideas for other researchers.

Development of a modified ABC method among Helicobacter pylori infected but serum pepsinogen test-negative individuals

BACKGROUND

Although the ABC method for gastric cancer (GC) screening has been widely adopted in Japan, it may not be suitable for other countries due to population heterogeneity and different tumor histology. We aim to develop a modified ABC method to improve GC screening performance, especially among Helicobacter pylori (Hp) infected but serum pepsinogen (sPG) test-negative individuals.

METHODS

A total of 4745 participants were recruited from Tianjin, China, and were classified into four groups by combined assay for Hp infection and sPG concentrations: Group A (Hp [-], PG [-]), Group B (Hp [+], PG [-]), Group C (Hp [+], PG [+]), and Group D (Hp [-], PG [+]). We used receiver-operating characteristic (ROC) curves analysis and minimum p value method to determine the optimal cutoff point for PG II in Group B. We performed logistic regressions to examine the risk of GC across different subgroups. In addition to the derivation set, the performance of the modified ABC method was also evaluated in an external set involving 16,292 participants from Liaoning, China.

RESULTS

In the modified ABC method, we further classified Group B as low-risk (Group B1) and high-risk subgroups (Group B2) using optimal sPG II cutoff point (20.0 ng/mL) by ROC curves analysis and minimum p value method. Compared with Group B1, Group B2 had a significantly higher risk of GC (adjusted OR = 2.54, 95% CI = 1.94-3.33). The modified ABC method showed good discrimination for GC (AUC = 0.61, 95% CI = 0.59-0.63) and improved risk reclassification (NRI = 0.11, p < .01). Similar results were observed in the validation dataset.

CONCLUSIONS

The modified ABC method can effectively identify high-risk population for GC among Hp-infected but sPG test-negative participants in China.

Investigation of the prevalence and risk factors of Helicobacter pylori infection and the value of different gastric cancer screening methods in a low-risk region of gastric cancer in China

BACKGROUND

The aim of this current study was to identify the prevalence and risk factors of H. pylori infection in the low-risk area of gastric cancer in China, and evaluate the value of different gastric cancer screening methods.

METHODS

An epidemiological study was conducted in Yudu County, Jiangxi, China, and participants were followed up for 6 years. All participants completed a questionnaire, laboratory tests and endoscopy. Patients were divided into H. pylori positive and negative groups, and risk factors for H. pylori infection were identified using multivariate logistic regression analysis.

RESULTS

A total of 1962 residents were included, the prevalence of H. pylori infection was 33.8%. Multivariate analysis showed that annual income ≤20,000 yuan (OR: 1.44, 95% CI: 1.18-1.77, p < 0.001), loss of appetite (OR: 1.71, 95% CI: 1.29-2.26, p < 0.001), PG II >37.23 ng/mL (OR: 2.11, 95% CI: 1.50-2.97, p < 0.001), G-17 > 1.5 and ≤5.7 pmol/L (OR: 2.52, 95% CI: 1.93-3.30, p < 0.001), and G-17 > 5.7 pmol/L (OR: 1.96, 95% CI: 1.48-2.60, p < 0.001) were risk factors of H. pylori infection, while alcohol consumption (OR: 0.70, 95% CI: 0.54-0.91, p = 0.006) was a protective factor. According to the new gastric cancer screening method, the prevalence of low-grade intraepithelial neoplasia in the low-risk group, medium-risk group and high-risk group was 4.4%, 7.7% and 12.5% respectively (p < 0.001).

CONCLUSIONS

In a low-risk area of gastric cancer in China, the infection rate of H. pylori is relatively low. Low income, loss of appetite, high PG II, and high G-17 were risk factors for H. pylori infection, while alcohol consumption was a protective factor. Moreover, the new gastric cancer screening method better predicted low-grade intraepithelial neoplasia than the ABC method and the new ABC method.

Autoimmune gastritis: long-term natural history in naïve Helicobacter pylori-negative patients

OBJECTIVE

Autoimmune gastritis (AIG) is an immunomediated disease targeting parietal cells, eventually resulting in oxyntic-restricted atrophy. This long-term follow-up study aimed at elucidating the natural history, histological phenotype(s), and associated cancer risk of patients with AIG consistently tested H. pylori-negative (naïve H. pylori-negative subjects).

DESIGN

Two-hundred eleven naïve H. pylori-negative patients (tested by serology, histology, molecular biology) with AIG (F:M=3.15:1; p<0.001) were prospectively followed up with paired biopsies (T1 vs T2; mean follow-up years:7.5 (SD:4.4); median:7). Histology distinguished non-atrophic versus atrophic AIG. Atrophy was further subtyped/scored as non-metaplastic versus metaplastic (pseudopyloric (PPM) and intestinal (IM)). Enterochromaffin-like-cell (ECL) status was categorised as diffuse versus adenomatoid hyperplasia/dysplasia, and type 1 neuroendocrine tumours (Type1-NETs).

RESULTS

Over the long-term histological follow-up, AIG consistently featured oxyntic-predominant-mononuclear inflammation. At T1, PPM-score was greater than IM (200/211 vs 160/211, respectively); IM scores increased from T1 to T2 (160/211 to 179/211), with no changes in the PPM prevalence (T1=200/211; T2=201/211). At both T1/T2, the prevalence of OLGA-III-stage was <5%; no Operative Link on Gastritis Assessment (OLGA)-IV-stage occurred. ECL-cell-status progressed from diffuse to adenomatoid hyperplasia/dysplasia (T1=167/14 vs T2=151/25). Type1-NETs (T1=10; T2=11) always coexisted with extensive oxyntic-atrophy, and ECL adenomatoid-hyperplasia/dysplasia. No excess risk of gastric or other malignancies was found over a cumulative follow-up time of 10 541 person years, except for (marginally significant) thyroid cancer (SIR=3.09; 95% CI 1.001 to 7.20).

CONCLUSIONS

Oxyntic-restricted inflammation, PPM (more than IM), and ECL-cell hyperplasia/neoplasia are the histological AIG hallmarks. Compared with the general population, corpus-restricted inflammation/atrophy does not increase the GC risk. The excess of GC risk reported in patients with AIG could plausibly result from unrecognised previous/current H. pylori comorbidity.