Pepsinogens: physiology, pharmacology pathophysiology and exercise

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.

Expression pattern and cellular localization of pepsinogen in early development and induced by different diets in the spotted knifejaw (Oplegnathus punctatus)

To solve the high mortality rate of early-stage larval feed conversion during aquaculture in Oplegnathus punctatus, the investigation of the structural and functional characteristics of the gastric tissue was conducted. Histological results showed that the gastric gland rudiment appeared at 17 dph. The basic structure of the stomach was fully developed between 26 and 35 dph. Two pepsinogen genes, named OpPGA1 and OpPGA2, were identified in the spotted knifejaw genome. qPCR results of developmental period showed that the two genes were low in expression during early development (5 and 15 dph). At 20 dph, the two genes started to show trace expression, and at 30 dph the mRNA expression levels of OpPGA1 and OpPGA2 reached the highest levels. Results of pepsin activity detection during the development period showed lower activity was detected 22 dph, followed by a peak at 30 dph. Under different feeding inductions, OpPGA1 showed the highest expression in the basic diet group and hard-shell group, while the expression level in the phytophagous group remained consistently low. The mRNA expression level of OpPGA2 in the phytophagous group was significantly higher than in other groups. Enzyme activity determination under different feeding inductions showed slightly higher enzyme activity in the basic diet group and crustacean group. The results of in situ hybridization showed that the mRNA of both OpPGA1 and OpPGA2 genes was both expressed in gastric gland cells. These information can contribute to the development of practical feeding methods in terms of digestive physiology for the development of larvae.

Pepsinogen ratio and brachial-ankle pulse wave velocity: a cross-sectional study on their interrelationship in atherosclerosis

BACKGROUND

Existing research has established the pepsinogen ratio (PGR) as a complex biomarker, not only as an independent predictor for various gastrointestinal diseases but also in its association with atherosclerotic cardiovascular diseases. However, the precise mechanism linking changes in PGR to cardiovascular pathologies remains unclear. The objective of this study is to quantitatively elucidate the association between PGR and brachial-ankle pulse wave velocity (baPWV) as an indicator of atherosclerotic progression.

METHODS

We conducted a cross-sectional study that analyzed clinical data from 465 patients who underwent health screenings. One-way Analysis of Variance (ANOVA) identified potential risk factors affecting baPWV. Multiple logistic regression was employed to evaluate if PGR serves as an independent risk factor for elevated baPWV after accounting for these variables. Generalized additive models and smoothed curve fitting were utilized to investigate the possibility of a nonlinear association between PGR and baPWV. When such nonlinearity was found, threshold effect analysis pinpointed the inflection point in this relationship, followed by segmented correlation analyses.

RESULTS

PGR negatively correlated with both right baPWV (RbaPWV) and left baPWV (LbaPWV) after adjusting for confounders. Smoothed curve analyses revealed nonlinear relationships, with inflection points at 22.5 for RbaPWV and 22.3 for LbaPWV. For PGR values below 22.5, a significant negative correlation with RbaPWV was observed (β = - 6.3 cm/s, P < 0.001). Conversely, for PGR values above 22.5, no significant linear relationship was found (P = 0.141). Similarly, when PGR was below 22.3, a strong negative correlation with LbaPWV was detected (β = - 7.0 cm/s, P < 0.001), but such correlation was absent for higher PGR levels (P = 0.273).

CONCLUSION

The study reveals that PGR is associated with RbaPWV and LbaPWV in a nonlinear manner. Specifically, lower levels of PGR were linearly and inversely correlated with baPWV, but this relationship became nonlinear at higher PGR levels. These findings suggest that modulating PGR levels may offer a therapeutic strategy for managing atherosclerosis.

Identification of serologically active Helicobacter pylori antigens related to alterations in serum pepsinogen levels

Gastric adenocarcinoma is associated with Helicobacter pylori infection. The transition to a carcinogenic process is preceded by glandular atrophy and serum levels of pepsinogen I and II (PGI and PGII) correlate with this type of gastric lesions. Possible associations of serum PG levels in relation to the frequency of serological activity against H. pylori antigens were studied. Serum samples from patients with gastric pathology associated with H. pylori (n=26) and asymptomatic individuals as controls (n=37) were used. Seroactive antigens were identified by immunoblot using a protein extract of H. pylori. The antibody titers anti-H. pylori and the concentration of PGs in serum was determined by ELISA. Thirty-one seroactive antigens were identified, nine of which exhibited a differential frequency between both groups (116.7, 68.8, 61.9, 54.9, 45.6, 38.3, 36.5, 33.8 and 30.1kDa) and only 3 were related to altered levels of PGs in serum. In the control group, the seropositivity of the 33.8kDa antigen was related to an increase in PGII, while the 68.8kDa antigen was related to normal PG values (decreased PGII and elevated PGI/PGII levels) indicating that seropositivity to this antigen could be a protective factor to gastric pathology. The seropositivity of the 54.9kDa antigen was related to altered values of PGs indicative of inflammation and gastric atrophy (increased in PGII and decreased in PGI/PGII). The identification of serum alterations in pepsinogen levels related to seropositivity to H. pylori 33.8, 54.9 and 68.8kDa antigens sets a precedent for further study as possible prognostic serological biomarkers.

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.

Serum pepsinogen level as a biomarker for atrophy, reflux esophagitis, and gastric cancer screening in Indonesia

Background

Chronic dyspepsia's symptoms are frequently seen in primary to tertiary healthcare in Indonesia. This study aimed to describe the potential usability of pepsinogen (PG) values in determining gastric mucosal conditions, including superficial gastritis and atrophic gastritis.

Materials and Methods

We recruited 646 adult dyspeptic patients and then analyzed PG values (including PGI, PGII, and PGI/II ratio) with endoscopic findings, gastric mucosal damages, and Helicobacter pylori infection. The gastric mucosal damage and H. pylori infection were evaluated using histological examination based on the updated Sydney system.

Results

Among 646 enrolled patients, 308 (47.2%), 212 (32.8%), 91 (14.1%), 34 (5.2%), and 1 (0.2%) patient were diagnosed with normal mucosa, gastritis, reflux esophagitis, peptic ulcer disease, and gastric cancer, respectively. Significant differences in PGI, PGII, and PGI/II ratio values were observed among ethnic groups (all P < 0.01). The PGI and PGII levels were significantly higher and PGI/II was significantly lower in H. pylori-infected patients than in uninfected ones (all P < 0.001). The optimal cutoff value for PGII and PGI/II was 12.45 ng/mL with an area under the curve (AUC) value of 0.755 (0.702-0.811), sensitivity 59.3%, and specificity 77.1%; and 4.75 with AUC value of 0.821 (0.763-0.855), sensitivity 81.5%, and specificity 78.7%, respectively, to determine moderate-severe atrophy.

Conclusion

Serum PG levels, a useful biomarker, represent the endoscopic findings, especially for reflux esophagitis. In addition, the benefits of PG values detecting atrophic gastritis were limited to moderate-severe atrophic gastritis. This usefulness requires careful attention for several ethnic groups in Indonesia.

Spatial-temporal mapping of the intra-gastric pepsin concentration and proteolysis in pigs fed egg white gels

While there is a consensus that food structure affects food digestion, the underlying mechanisms remain poorly understood. A previous experiment in pigs fed egg white gels of same composition but different structures evidenced such effect on food gastric disintegration. In this study, we detailed the consequences on intra-gastric pH, pepsin concentration and proteolysis by sampling throughout the stomach over 6 h digestion. Subsequent amino acid absorption was investigated as well by blood sampling. While acidification was almost homogeneous after 6 h digestion regardless of the gel, pepsin distribution never became uniform. Pepsin started to accumulate in the pylorus/antrum region before concentrating in the body stomach beyond 4 h, time from which proteolysis really started. Interestingly, the more acidic and soft gel resulted in a soon (60 min) increase in proteolysis, an earlier and more intense peak of plasmatic amino acids, and a final pepsin concentration three times higher than with the other gels.

Low serum pepsinogen II levels are closely linked with a risk of metabolic syndrome among healthy individuals with asymptomatic Helicobacter pylori infection: a cross-sectional study

Aim: Helicobacter pylori (Hp) infection has a connection with metabolic syndrome (MetS). Pepsinogen II (PGII) is a marker for gastric epithelial function. The present research was aimed at determining the associations among serum PGII levels, Hp infection and MetS in healthy subjects. Methods: This cross-sectional study enrolled 1242 healthy people, including 545 subjects with asymptomatic Hp infection and 697 subjects without Hp infection. Based on the number of MetS components present, subjects with Hp infection were assigned to the following groups: group 1, no component (126 subjects); group 2, one or two components (260 subjects); and group 3, three or more components (159 subjects). Physical measurements and biochemical indices were recorded. Serum PGII levels were recorded using ELISA. SPSS and GraphPad Prism were used for statistical analyses. Results: Among subjects with Hp infection, serum PGII was evidently downregulated in group 3 compared with group 1 (14.95 ± 8.24 vs 17.97 ± 9.08 μg/l; p = 0.015). Serum PGII levels were correlated with an increased risk of MetS (odds ratio: 0.867; 95% CI: 0.772-0.974; p = 0.016), as indicated by the multivariate logistic regression analysis. Grouping subjects with Hp infection according to quartiles of serum PGII levels identified an evident difference in MetS prevalence among the four quartile-based groups (p = 0.047). Conclusions: Among healthy subjects with asymptomatic Hp infection, serum PGII levels were lower in those with MetS than in those without MetS. Serum PGII levels showed an independent and negative correlation with the risk of MetS in healthy subjects with Hp infection.

Pepsinogen II in gastritis and Helicobacter pylori infection

BACKGROUND AND AIM

In the gastric mucosa, pepsinogen II (PgII) is produced/secreted by glands in the mucus-secreting antral and cardia compartments, but also by the chief cells and the oxyntic glands. Increasing PgII serum levels are associated with the whole spectrum of gastric inflammatory diseases, including gastritis induced by Helicobacter pylori (H. pylori). This review critically addresses the clinical value of PgII serology for assessing gastric mucosal inflammation, and as a marker of H. pylori status, in both H. pylori-positive patients and after eradication therapy.

RESULTS

A search in PubMed/Scopus records yielded 39 out of 1190 published scientific studies meeting the selection criteria for this study. In the studies considered, PgII levels were significantly associated with non-atrophic gastric inflammatory lesions (p-values: 0.025-0.0001). H. pylori-positive patients had significantly higher PgII levels than H. pylori-negative individuals (p-values: 0.o5-0.0001). While a significant drop in serum PgII levels is consistently reported in H. pylori-eradicated patients (p-values: from 0.05 to 0.0001), inconsistencies in the related negative and positive predictive values significantly lower the clinical reliability of PgII testing by comparison with other available non-invasive tests.

CONCLUSIONS

PgII serology may provide clinically useful information on gastric inflammatory diseases, particularly if they are non-atrophic. PgII serology is inconsistent, however, for the purposes of distinguishing patients whose H. pylori eradication therapy is successful from those who remain infected.

Determination of pepsin by capillary electrophoresis using mixed polymer coated capillary with switchable properties towards protein adsorption/desorption

In this work, a simple on-line preconcentration method for quantitative detection of pepsin was realized by using the binary mixed polymer brushes coated capillary with switchable properties towards protein adsorption. Firstly, the binary mixed polymer brushes were prepared by grafting poly(2-methyl-2-oxazoline) and poly(4-vinylpyridine) onto the inner wall of the capillary through polydopamine anchor. Then the coatings were characterized by X-ray photoelectron spectrometer and electroosmotic flow measurement. The results indicated that the composition of coating could be controlled by varying the feed ratio of poly(2-methyl-2-oxazoline) to poly(4-vinylpyridine) and the inner surface charge could be tuned toward the change of pH and ionic strength. The results showed when poly(2-methyl-2-oxazoline)/poly(4-vinylpyridine) mass ratio was 80/20, the highest on-line preconcentration effect was obtained and the sensitivity enhancement factor was 6.3. Moreover, satisfactory sensitivity (limit of detection: 7.5 ng/mL) and good repeatability were obtained with on-line preconcentration method. The polymer coated capillary was still stable for on-line preconcentration and detection of pepsin after 50 consecutive runs. Lastly, the proposed method was used successfully to on-line preconcentrate pepsin in saliva matrix. This article is protected by copyright. All rights reserved.

Review of paediatric gastrointestinal physiology relevant to the absorption of orally administered medicines

Despite much progress in regulations to improve paediatric drug development, there remains a significant need to develop better medications for children. For the design of oral dosage forms, a detailed understanding of the specific gastrointestinal (GI) conditions in children of different age categories and how they differ from GI conditions in adults is essential. Several review articles have been published addressing the ontogeny of GI characteristics, including luminal conditions in the GI tract of children. However, the data reported in most of these reviews are of limited quality because (1) information was cited from very old publications and sometimes low quality sources, (2) data gaps in the original data were filled with textbook knowledge, (3) data obtained on healthy and sick children were mixed, (4) average data obtained on groups of patients were mixed with data obtained on individual patients, and (5) results obtained using investigative techniques that may have altered the outcome of the respective studies were considered. Consequently, many of these reviews draw conclusions that may be incorrect. The aim of the present review was to provide a comprehensive and updated overview of the available original data on the ontogeny of GI luminal conditions relevant to oral drug absorption in the paediatric population. To this end, the PubMed and Web of Science metadatabases were searched for appropriate studies that examined age-related conditions in the oral cavity, esophagus, stomach, small intestine, and colon. Maturation was observed for several GI parameters, and corresponding data sets were identified for each paediatric age group. However, it also became clear that the ontogeny of several GI traits in the paediatric population is not yet known. The review article provides a robust and valuable data set for the development of paediatric in vitro and in silico biopharmaceutical tools to support the development of age-appropriate dosage forms. In addition, it provides important information on existing data gaps and should provide impetus for further systematic and well-designed in vivo studies on GI physiology in children of specific age groups in order to close existing knowledge gaps and to sustainably improve oral drug therapy in children.

Distribution of transient receptor potential vanilloid-1 channels in gastrointestinal tract of patients with morbid obesity

BACKGROUND

Transient receptor potential vanilloid-1 (TRPV1), a nonselective cation channel, is activated by capsaicin, a pungent ingredient of hot pepper. Previous studies have suggested a link between obesity and capsaicin-associated pathways, and activation of TRPV1 may provide an alternative approach for obesity treatment. However, data on the TRPV1 distribution in human gastric mucosa are limited, and the degree of TRPV1 distribution in the gastric and duodenal mucosal cells of obese people in comparison with normal-weight individuals is unknown.

AIM

To clarify gastric and duodenal mucosal expression of TRPV1 in humans and compare TRPV1 expression in obese and healthy individuals.

METHODS

Forty-six patients with a body mass index (BMI) of > 40 kg/m² and 20 patients with a BMI between 18-25 kg/m² were included. Simultaneous biopsies from the fundus, antrum, and duodenum tissues were obtained from subjects between the ages of 18 and 65 who underwent esophagogastroduodenoscopy. Age, sex, history of alcohol and cigarette consumption, and past medical history regarding chronic diseases and medications were accessed from patient charts and were analyzed accordingly. Evaluation with anti-TRPV1 antibody was performed separately according to cell types in the fundus, antrum, and duodenum tissues using an immunoreactivity score. Data were analyzed using SPSS 17.0.

RESULTS

TRPV1 expression was higher in the stomach than in the duodenum and was predominantly found in parietal and chief cells of the fundus and mucous and foveolar cells of the antrum. Unlike foveolar cells in the antrum, TRPV1 was relatively low in foveolar cells in the fundus (4.92 ± 0.49 vs 0.48 ± 0.16, P < 0.01, Mann-Whitney U test). Additionally, the mucous cells in the duodenum also had low levels of TRPV1 compared to mucous cells in the antrum (1.33 ± 0.31 vs 2.95 ± 0.46, P < 0.01, Mann-Whitney U test). TRPV1 expression levels of different cell types in the fundus, antrum, and duodenum tissues of the morbidly obese group were similar to those of the control group. Staining with TRPV1 in fundus chief cells and antrum and duodenum mucous cells was higher in patients aged ≥ 45 years than in patients < 45 years (3.03 ± 0.42, 4.37 ± 0.76, 2.28 ± 0.55 vs 1.9 ± 0.46, 1.58 ± 0.44, 0.37 ± 0.18, P = 0.03, P < 0.01, P < 0.01, respectively, Mann-Whitney U test). The mean staining levels of TRPV1 in duodenal mucous cells in patients with diabetes and hypertension were higher than those in patients without diabetes and hypertension (diabetes: 2.11 ± 0.67 vs 1.02 ± 0.34, P = 0.04; hypertension: 2.42 ± 0.75 vs 1.02 ± 0.33, P < 0.01 Mann-Whitney U test).

CONCLUSION

The expression of TRPV1 is unchanged in the gastroduodenal mucosa of morbidly obese patients demonstrating that drugs targeting TRPV1 may be effective in these patients.

Serum pepsinogen II levels are doubled with Helicobacter pylori infection in an asymptomatic population of 40,383 Chinese subjects

Pepsinogen (PG) I and II are crucial in the gastric digestive processes. This study is to examine the relationship of serum PGI, PGII, and PGI/PGII ratio with Helicobacter pylori (Hp) infection, age, sex, and body mass index (BMI) in subjects in Beijing, China.A total of 40,383 asymptomatic subjects, who underwent medical examination in Beijing Rehabilitation Hospital, were included in this study. Serum PG levels were measured using chemoluminescence techniques. The age, sex, and BMI data were collected, and Hp infection was identified with 13C-urea breath test. Statistical analysis was conducted with Python, Pandas and Seaborn software.Asymptomatic subjects with Hp infection (Hp+) had a significantly higher level of PGI in the serum (111 ng/mL [median]) than those without Hp infection (Hp-) (94 ng/mL, P < .001). The asymptomatic Hp+ subjects had 2-fold higher PGII levels (7.2 ng/mL) than Hp- subjects (3.2 ng/mL, P < .001). These changes produced significantly lower PGI/II ratio in Hp+ patients than in Hp- subjects (16:30, P < .001). The serum PGI and PGII levels were higher in males than in females (PGI: 104 ng/mL vs 95 ng/mL, PGII: 4.3 ng/mL vs 3.7 ng/mL, both P < .001), PGI/II ratio of males is at 95% of that in females (P < .001). PGI and PGII levels gradually increased in older people (P < .001), whereas the PGI/II ratio decreased significantly with age (P < .001). The levels of the two serum PGs were decreased and the ratio increased when BMI were higher than 28 kg/cm2 (P < .05).The levels of serum PGI, especial PGII, were increased by Hp infection, and also influenced by age, sex, and BMI. Therefore, these influencing factors should be considered during clinical practice.

Proteomics signature of autoimmune atrophic gastritis: towards a link with gastric cancer

BACKGROUND

Autoimmune atrophic gastritis (AAG) is a chronic disease that can progress to gastric cancer (GC). To better understand AAG pathology, this proteomics study investigated gastric proteins whose expression levels are altered in this disease and also in GC.

METHODS

Using two-dimensional difference gel electrophoresis (2D-DIGE), we compared protein maps of gastric corpus biopsies from AAG patients and controls. Differentially abundant spots (|fold change|≥ 1.5, P < 0.01) were selected and identified by LC-MS/MS. The spots were further assessed in gastric antrum biopsies from AAG patients (without and with Helicobacter pylori infection) and from GC patients and unaffected first-degree relatives of GC patients.

RESULTS

2D-DIGE identified 67 differentially abundant spots, with 28 more and 39 less abundant in AAG-corpus than controls. LC-MS/MS identified these as 53 distinct proteins. The most significant (adjusted P < 0.01) biological process associated with the less abundant proteins was "tricarboxylic acid cycle". Of the 67 spots, 57 were similarly differentially abundant in AAG-antrum biopsies irrespective of H. pylori infection status. The differential abundance was also observed in GC biopsies for 14 of 28 more abundant and 35 of 39 less abundant spots, and in normal gastric biopsies of relatives of GC patients for 6 and 25 spots, respectively. Immunoblotting confirmed the different expression levels of two more abundant proteins (PDIA3, GSTP gene products) and four less abundant proteins (ATP5F1A, PGA3, SDHB, PGC).

CONCLUSION

This study identified a proteomics signature of AAG. Many differential proteins were shared by GC and may be involved in the progression of AAG to GC.

Protective Effect of Ultraviolet C Irradiation on the Gastric Mucosa of Rats with Chronic Gastritis Induced by Physicochemical Stimulations

Background

Chronic gastritis (CG) is a common digestive disease with the highest morbidity among multiple digestive diseases, which seriously lowers the life quality of patients. The pathological alternations of gastric mucosa, and its possible mechanisms have been the focus of CG-related researches. Accumulative basic and clinical evidence has confirmed that ultraviolet C (UVC) is effective in relieving superficial acute infective inflammation, skin and mucous membrane injuries, and ulcers, and promoting wound healing.

Objective

This study was aimed at investigating the protective effects of UVC on gastric mucosal injury in rats stimulated with physicochemical irritants like ethanol and exploring the mechanisms underlying the protection by UVC against gastric mucosal injury and CG.

Methods

Fifty Wistar rats were randomly divided into five groups, including Group A (normal), Group B (model), Group C (omeprazole treatment), Group D (intragastric UVC irradiation for 24 s × 2 yields), and Group E (intragastric UVC irradiation for 48 s × 2 yields). Rats in Groups B-E were made CG model by physicochemical stimulations. All rats were sacrificed one week after the 22-week experiment, and gastric tissues were harvested. Histopathological examinations were performed. The activities of superoxide dismutase and catalase as well as the contents of reduced glutathione and malondialdehyde in gastric mucosal tissues were detected. Serum interleukin-6, interleukin-1beta, tumor necrosis factor-alpha, pepsin, and gastrin were measured.

Results

Results showed that physiochemical irritants like ethanol could be used for easily establishing a rat CG model that shared similar pathological features with human CG. Intragastric UVC irradiation could promote the repair of gastric mucosa and improve the atrophy of gastric mucosa by inhibiting the inflammatory factors, increasing the levels of pepsin and gastrin, decreasing the expression of lipid peroxide, and enhancing the activity of superoxide dismutase and catalase and the levels of reduced glutathione. UVC irradiation for 48 s × 2 yields showed the strongest protective effect.

Conclusion

UVC irradiation could inhibit the inflammatory factors, activate the antioxidative system, and enhance the secretion of pepsin and gastrin, which promoted the repair of injured gastric mucosa and improved gastric mucosa atrophy.

In Situ Gastric pH Imaging with Hydrogel Capsule Isolated Paramagnetic Metallo-albumin Complexes

Abnormal gastric pH (pH > 3) has instructive significance for early diagnosis of various diseases, including cancer. However, for low patient compliance, limited penetration depth, high dependence on physiological function or unsafety issue, in situ noninvasive monitoring gastric pH is challenged. Herein, we developed a hydrogel capsule isolated human serum albumin-manganese complex (HSA-Mn) for in situ magnetic resonance imaging (MRI) gastric pH monitoring for the first time. In this strategy, the rotation motion restriction of Mn²⁺ after binding to HSA significantly increased the R₁ (longitudinal relaxation rate) signal, and its high correlation with protonation imparted the HSA-Mn system sensitive responsiveness to varying pH (R₁(pH 7)/R₁(pH 1) = 8.2). Moreover, a screw jointed hydrogel capsule with signal confinement and internal standard abilities was designed. Such a nanoporous hydrogel capsule with size selectivity to surrounding molecules enabled a stable and sensitive response to different pH simulated gastric fluid within 0.5 h. In addition, with the unique structural outline and stable MRI characteristics, the capsule could also work as an internal standard, which facilitates the collection of signals and trace of the capsule in vivo. Through validating in a rabbit model, the precise abnormal gastric pH recognition capacity of the HSA-Mn hydrogel capsule was amply confirmed. Hence, the hydrogel capsule isolated HSA-Mn system strategy with great biocompatibility could be expected to be a potent tool for in situ anti-disturbance MRI of gastric pH in future clinical application.

The Level of Serum Pepsinogen in Diagnosing and Evaluating the Severity of Subacute Combined Degeneration Due to Vitamin B12 Deficiency

Subacute combined degeneration (SCD) is a neurological complication of cobalamin deficiency, which is usually caused by chronic autoimmune atrophic gastritis. Serum pepsinogen 1 and the ratio of pepsinogen 1/pepsinogen 2 (PG1/2) can reflect the severity of gastric atrophy.

Objective: This work aims to investigate whether decreased serum PG1 and PG1/2 ratio are helpful in diagnosing SCD and reflecting the severity of SCD.

Methods: We retrospectively analyzed the clinical and laboratory tests of 65 cases of SCD due to vitamin B12 deficiency and compared the laboratory parameters of SCD with 65 age- and sex-matched amyotrophic lateral sclerosis (ALS) patients.

Results: PG1 and PG1/2 ratio were decreased in 80 and 52.3% of SCD patients, respectively. Compared to patients with PG1/2 ratio ≥3.0, patients with PG1/2 ratio <3.0 had more severe anemia, larger mean corpuscular volume (MCV), lower level of vitamin B12, higher folate and homocysteine (Hcy), more severe changes in somatosensory evoked potential (SEP), and higher rate of lesions in spinal MRI (P < 0.05). PG1 and PG1/2 ratio had inverse correlation with MCV and N20 latency in SEP examination (P < 0.05). PG1/2 ratio, RBC count, and Hcy were independent risk factors for SCD in logistic regression analyses. The ROC curve analysis revealed that the diagnostic accuracy of PG1 and PG1/2 ratio was 72.2 and 73.0%, respectively, while the cutoff values were 22.4 ng/ml and 2.43 for SCD, respectively.

Conclusions: Decreased PG1 and PG1/2 ratio are helpful for the diagnosis and evaluation of the severity of SCD due to vitamin B12 deficiency.

Molecular and cellular cues governing nanomaterial-mucosae interactions: from nanomedicine to nanotoxicology

Mucosal tissues constitute the largest interface between the body and the surrounding environment and they regulate the access of molecules, supramolecular structures, particulate matter, and pathogens into it. All mucosae are characterized by an outer mucus layer that protects the underlying cells from physicochemical, biological and mechanical insults, a mono-layered or stratified epithelium that forms tight junctions and controls the selective transport of solutes across it and associated lymphoid tissues that play a sentinel role. Mucus is a gel-like material comprised mainly of the glycoprotein mucin and water and it displays both hydrophilic and hydrophobic domains, a net negative charge, and high porosity and pore interconnectivity, providing an efficient barrier for the absorption of therapeutic agents. To prolong the residence time, absorption and bioavailability of a broad spectrum of active compounds upon mucosal administration, mucus-penetrating and mucoadhesive particles have been designed by tuning the chemical composition, the size, the density, and the surface properties. The benefits of utilizing nanomaterials that interact intimately with mucosae by different mechanisms in the nanomedicine field have been extensively reported. To ensure the safety of these nanosystems, their compatibility is evaluated in vitro and in vivo in preclinical and clinical trials. Conversely, there is a growing concern about the toxicity of nanomaterials dispersed in air and water effluents that unintentionally come into contact with the airways and the gastrointestinal tract. Thus, deep understanding of the key nanomaterial properties that govern the interplay with mucus and tissues is crucial for the rational design of more efficient drug delivery nanosystems (nanomedicine) and to anticipate the fate and side-effects of nanoparticulate matter upon acute or chronic exposure (nanotoxicology). This review initially overviews the complex structural features of mucosal tissues, including the structure of mucus, the epithelial barrier, the mucosal-associated lymphatic tissues and microbiota. Then, the most relevant investigations attempting to identify and validate the key particle features that govern nanomaterial-mucosa interactions and that are relevant in both nanomedicine and nanotoxicology are discussed in a holistic manner. Finally, the most popular experimental techniques and the incipient use of mathematical and computational models to characterize these interactions are described.

Association between serum pepsinogen and atherosclerotic cardiovascular disease

BACKGROUND AND AIM

Serum pepsinogens (PGs) are biomarkers for gastric mucosal damage and have been reported to be associated with atherosclerosis. Its correlation with atherosclerotic cardiovascular disease (ASCVD) is still unknown. This study aimed to explore the association between serum PGs and ASCVD for providing physicians with an integrative picture to make rational plans in the diagnosis and treatment of ASCVD.

METHODS AND RESULTS

The concentrations of serum PGs and their distributions between ASCVD and non-ASCVD were compared by non-parametric test, Chi-squared test and Fisher exact test. The correlation between variables was analyzed by Spearman's correlation test. The association of serum PGs with ASCVD was analyzed by the binary logistic regression and two-piecewise linear regression. A total of 8355 recruited cases were eligible for the study. The concentrations of serum PGs were significantly different between the ASCVD and non-ASCVD groups (P = 0.025, P < 0.001). The lower PGI and PGR levels were significantly correlated with a high risk of ASCVD presence after adjustment for 26 potential covariates. Moreover, there was a linear relationship between the high level of PGII and the high risk of ASCVD [adjusted OR = 1.16 (1.00, 1.37), P = 0.07]. A nonlinear relationship of PGI/PGR and ASCVD (P = 0.08/<0.001) was also revealed. The risk of ASCVD increased with a range of log PGI ≥2.13 (PGI≥131 ng/mL) [adjusted OR = 4.67 (1.00, 23.17)], and decreased with a range of log PGR ≥0.22 (1.65) [adjusted OR = 0.59 (0.48, 0.74), P < 0.001].

CONCLUSIONS

Serum PGI and PGR are nonlinearly correlated with ASCVD, while PGII is linearly correlated with ASCVD. Among all PGs, PGR may serve as a reliable biomarker for ASCVD.

Changes of serum pepsinogen level and ABC classification after bariatric surgery

BACKGROUND

Very few studies have explored the changes of serum pepsinogen after bariatric surgery and no research has evaluated the feasibility of ABC classification to predict gastric cancer risk after bariatric surgery.

METHODS

We enrolled 94 obese subjects that received bariatric surgery, including 41 sleeve gastrectomy (SG) and 53 Roux-en-Y gastric bypass (RYGB). The serum pepsinogen I (PGI), pepsinogen II (PGII), PGI/II ratio and seropositivity of Helicobacter pylori ( H. pylori ) were measured before and one year after surgery. Patients were classified according to ABC classification and post-operative change was evaluated.

RESULTS

Preoperatively, four (4.2%) patients were classified into high risk group (classification C and D) for gastric cancer. Significant reduction of PGI, PGII and decrease of PGI/II ratio were noted after bariatric surgery. H. pylori seropositive patients had a greater postoperative change of PGI (-38.6μg/L vs -22.1μg/L, p=0.003) and PGII (-8.0μg/L vs -2.5μg/L, p <0.001) but a less postoperative change of PGI/II ratio (-0.6 vs -2.1, p =0.04) than H. pylori seronegative patients. One year after surgery, the portion of high risk group of ABC classification for gastric cancer increased markedly from 4.2% to 23.7%.

CONCLUSION

Both of SG and RYGB resulted in significant reduction of serum PGI and PGII after bariatric surgery, and significantly influenced the ABC classification. The application of ABC classification for gastric cancer screening was limited after bariatric surgery.

Protective Effects of Borago officinalis (Borago) on Cold Restraint Stress-Induced Gastric Ulcers in Rats: A Pilot Study

Stress is a typical body's natural defense to a generic physical or psychic change. A specific linking mechanism between ulcer onset and psycho-physical stress prolonged exposure has been reported. We decided to investigate the possible effects of Borago officinalis L. (Borago) in preventing physical (stress)-induced gastric ulcers in a rat model. Eighty male Sprague-Dawley rats were randomly divided into 16 groups, pretreated with a control solution, omeprazole (20 mg/kg), Borago methanolic extract (25, 50, 100, 250, and 500 mg/kg), Borago organic extract (50, 100, 250, and 500 mg/kg), Borago aqueous extract (5, 10, 20, 30, and 40 mg/kg), and D(-)-2-Amino-5-phosphonovaleric acid (AP5) (25 mg/kg) and kept in stressful conditions such as water immersion and restraint-induced stress ulcers. The animals were sacrificed and their stomach scored for the severity and the number of gastric ulcers. Methanolic extract (500 mg/kg) significantly reduced both ulcer parameters (^***p < 0.001 and ^**p < 0.01, respectively). Aqueous and organic extract significantly decreased severity score at 5 and 10 mg/kg (^**p < 0.01 and ^***p < 0.001, respectively), and at 250 and 500 mg/kg (^***p < 0.001), respectively, while gastric ulcers' resulted number significantly reduced only at 10 mg/kg (^*p < 0.05) and at 500 mg/kg (^**p < 0.01), respectively. On the other hand, aqueous extract significantly increased the mucosal gastric content of cAMP (^*p < 0.05) and NR2A and NR2B subunits (^*p < 0.05 and ^**p < 0.01, respectively) at 5 mg/kg. Organic extract showed also a significant cytotoxic effect at 500 and 1,000 mg/kg with a 3T3 cell viability reduction of 43.6% (^**p < 0.01) and 92.1% (^***p < 0.001), respectively. Borago aqueous extract at 10 mg/kg could be considered as a potential protective agent against stress-induced ulcers, and it is reasonable to possibly ascribe such protective activity to a modulation of the NR2A and NR2B subunit expression.

DIAGNOSTIC ACCURACY OF GASTROPANEL® FOR ATROPHIC GASTRITIS IN BRAZILIAN SUBJECTS AND THE EFFECT OF PROTON PUMP INHIBITORS

BACKGROUND

It has been proposed that the combination of gastrin-17 (G-17), pepsinogens I and II (PGI and PGII), and anti-Helicobacter pylori (H. pylori) antibodies (GastroPanel®, BIOHIT HealthCare, Helsinki, Finland) could serve as biomarkers of atrophic gastritis.

OBJECTIVE

This study aimed to ensure the diagnostic accuracy of GastroPanel® and evaluate the effect of proton pump inhibitors (PPIs) on these biomarkers.

METHODS

Dyspeptic patients who underwent gastrointestinal endoscopy were enrolled in the present study. Histological findings, which were the gold standard to stratify groups, were as follows: no atrophy (controls); antrum atrophy; corpus atrophy; multifocal atrophy; and neoplasia. G-17, PGI, PGII, and anti-H. pylori immunoglobulin (Ig)G antibodies were assayed using commercially available kits. The ratio of PGI/PGII was calculated.

RESULTS

Among 308 patients, 159 (51.6%) were PPI users. The overall prevalence of atrophy was 43.8% (n=135). Ninety-two (29.9%) patients were H. pylori positive according to anti-H. pylori IgG levels. G-17 levels were not low in those with antrum atrophy but were high in those with corpus and multifocal atrophies. PGI levels were significantly lower in those with corpus and multifocal atrophies. The sensitivity of PGI <30 µg/L to detect corpus atrophy was 50% (95% CI 27.8-72.1%), with a specificity of 93.2% (95% CI 84.3-97.5%), a positive likelihood ratio of 7.4 (95% CI 2.9-19.2), and a negative likelihood ratio of 0.5 (95% CI 0.3-0.8). A small number of subjects (n=6) exhibited moderate to intense atrophy (4%), among whom 66.7% exhibited decreased PGI levels. PPI significantly increased the levels of G-17 and PGI, except in those with corpus and multifocal atrophies, in whom PGI levels were not increased by PPIs.

CONCLUSION

GastroPanel® (Gastrin-17, PGI, and PGI/PGII ratio) did not demonstrate high sensitivity for detecting gastric atrophy.

Serum pepsinogens as a gastric cancer and gastritis biomarker in South and Southeast Asian populations

Serum pepsinogens have been widely acknowledged as gastric mucosal biomarkers; however, a multicountry report on the benefits of pepsinogens as biomarkers has not yet been published. We analyzed 1,206 sera and gastric mucosal samples collected from Bangladesh, Bhutan, Indonesia, Myanmar, Nepal and Thailand then assessed the association between gastric mucosal changes and Helicobacter pylori infection. The new cutoff values for serum pepsinogen values were evaluated using a receiver operating characteristic analysis. The participants with H. pylori infection had significantly lower pepsinogen I and higher pepsinogen II values, but a lower pepsinogen I/II ratio than participants without the infection (all P < .001). The pepsinogen I and pepsinogen I/II values were significantly higher and lower, respectively, in individuals with atrophic gastritis than in those without (both P < .001). Among uninfected individuals, only the pepsinogen I/II ratio was significantly lower in atrophic individuals. Pepsinogen I/II ratio also were significantly different between disease among H. pylori-positive and H. pylori-negative individuals, suggesting the pepsinogen I/II ratio is a robust biomarker for determining both chronic and atrophic gastritis. The cutoffs for detecting chronic and atrophic gastritis for the pepsinogen I/II ratio were 4.65 and 4.95, respectively. In conclusion, pepsinogen levels are useful biomarker for both chronic gastritis and atrophic gastritis, but they should be used with caution. Population-based validation is necessary to determine the best cutoff values. Among all pepsinogen values, the pepsinogen I/II ratio was the most reliable gastric mucosal-change biomarker.

Low Protein Digestibility of Beef Puree in Infant In Vitro Digestion Model

This study investigated protein digestibility of beef puree in infant and adult in vitro digestion models. The simulated digestive juices for infant and adult were prepared. Protein digestibility of beef puree was calculated in the gastric and gastrointestinal compartments. The 10% trichloroacetic acid soluble nitrogen and α-amino group contents of gastric digesta were lower in the infant in vitro digestion model than those in the adult in vitro digestion model (p<0.05). In addition, the gastrointestinal digesta from the infant in vitro digestion model had lower value of the 10% trichloroacetic acid soluble nitrogen and α-amino group contents than those of the adult in vitro digestion model (p<0.05). The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the remarkable bands of actin and myosin light chain B were found in the digesta of beef puree from the infant in vitro digestion model. The results of this study revealed the lower protein digestibility of beef puree in infants compared to that in adults. Therefore, the development of ways to increase digestibility of meat protein can improve the nutritional quality of meat products for infants.

Serum pepsinogen assay is not recommended for the diagnosis of esophageal squamous cell carcinoma: a systematic review and meta-analysis

Background: Serum pepsinogen I (PGI) concentration and PGI/PGII ratio (PGR) are often used as serological markers for gastric fundus atrophy (AGA) and gastric carcinoma. However, their diagnostic value in esophageal carcinoma (EC) is inaccurate. Methods: This study evaluated the diagnostic value of PGI and PGR in EC by searching the PubMed, Web of Science, Embase, Cochrane Library and Cochrane Central Register of Controlled Trials databases for literature on the diagnosis of EC with PGI and PGR from January 1, 2000 to October 2, 2018. The included literature were systematically evaluated using QUSDAS-2 software. Meta-analysis was conducted using STATA 15.0 software. The summary receiver operating characteristic curve (SROC) accuracy was plotted, the area under the curve was calculated. Results: A total of 84 papers were selected, and after screening, nine papers on esophageal squamous cell carcinoma (ESCC) were finally included. Results showed low an ESCC-specific diagnostic sensitivity (0.27), high specificity (0.85), and 0.63 AUC of SROC when PGI≤70 ng/mL. When PGR≤3, the ESCC-specific diagnostic sensitivity was low (0.29), the specificity was high (0.83), and the AUC of SROC was 0.63. Conclusion: According to the current research results, PGI≤70 ng/mL or PGR≤3 diagnostic ESCC sensitivity is low, and specificity is high. These findings indicate that neither PGI≤70 ng/mL nor PGR≤3 can be used as an ESCC-screening index.

Non-invasive method for the assessment of gastric acid secretion

Methods for the measure of gastric acid secretion include invasive and non-invasive tests. The gold-standard to measure the acid output is the collection of gastric after in basal condition (Basal Acid Output, B.A.O.) and after an i.m. injection of pentagastrin (Maximal Acid Output, M.A.O.). However, direct measurement of gastric acid production is out of order in clinical practice, but many GI symptoms are claimed to be related with acid disorders and empirically cured. Hypochlorhydria is associated with precancerous conditions such as chronic atrophic gastritis (CAG). Acid measurement with non-invasive methods (pepsinogens) is supported by international guidelines. (www.actabiomedica.it)

Gastric Cancer Screening by Combined Determination of Serum Helicobacter pylori Antibody and Pepsinogen Concentrations: ABC Method for Gastric Cancer Screening

Objective:

Gastroscopy combined with gastric mucosa biopsies is currently regarded as a gold standard for diagnosis of gastric cancer. However, its application is restricted in clinical practice due to its invasive property. A new noninvasive population screening process combining the assay of anti-Helicobacter pylori antibody and serum pepsinogen (PG) (ABC method) is adopted to recognize the high-risk patients for further endoscopy examination, avoiding the unnecessary gastroscopy for most population and saving the cost consumption for mass screening annually. Nevertheless, controversies exist for the grouping of ABC method and the intervals of gastroscopy surveillance for each group. In this review, we summarized these popular concerned topics for providing useful references to the healthcare practitioner in clinical practice.

Data Sources:

The PubMed databases were systematically searched from the inception dates to November 22, 2017, using the keywords “Helicobacter pylori,” “Pepsinogens,” and “Stomach Neoplasms.”

Study Selection:

Original articles and reviews on the topics were selected.

Results:

Anti-H. pylori antibody and serum PG concentration showed significant changes under the different status of H. pylori infection and the progression of atrophic gastritis, which can be used for risk stratification of gastric cancer in clinic. In addition, anti-H. pylori antibody titer can be used for further risk stratification of gastric cancer contributing to determine better endoscopy surveillance interval.

Conclusions:

The early detection and diagnosis of gastric cancer benefit from the risk stratification, but the cutoff values for H. pylori antibody and serum PG concentration require further modification.

Characteristics of Helicobacter pylori-seropositive subjects according to the stool antigen test findings: a prospective study

BACKGROUND/AIMS

In countries with a higher risk of gastric atrophic gastritis, noninvasive tests are helpful for a more reliable diagnosis of Helicobacter pylori infection. The aim of this study was to evaluate the characteristics of seropositive subjects according to their stool H. pylori antigen test, serum pepsinogen (PG) assay, and endoscopic findings.

METHODS

Consecutive subjects who visited Konkuk University Medical Center for upper gastrointestinal endoscopy for a regular check-up were included in a prospective setting if the serum anti-H. pylori immunoglobulin G assay was positive. A H. pylori antigen stool test was measured using a stool H. pylori antigen enzyme-linked immunosorbent assay kit on the same day as a serum PG assay and endoscopy.

RESULTS

Of 318 seropositive subjects, 256 (80.5%) showed positive stool test findings. Subjects with a negative stool test result showed lower serum PG I (p < 0.001) and PG II (p < 0.001) levels and higher PG I/II ratio (p < 0.001) than those with a positive stool test. Chronic atrophic gastritis was more common in the positive stool test group than the negative stool test group on endoscopic finding (p = 0.009). A higher serum PG I level (p = 0.001) and a lower serum PG I/II ratio (p = 0.001) were independent risk factors for the presence of H. pylori antigen in stool.

CONCLUSION

A high serum PG level denotes an ongoing current H. pylori infection with positive stool H. pylori antigen test findings. Seropositive subjects with increased gastric secreting ability tend to have H. pylori in their fecal material as reflected by a positive stool H. pylori antigen test finding.

Epstein-Barr virus infection associated with pepsinogens and Helicobacter pylori infection in patients with gastric cancer

BACKGROUND

There is no study reporting the influence of the Epstein-Barr virus (EBV) infection on the biomarkers of gastric function like pepsinogen (PG) I and II in patients with gastric cancer, and the relationship between the infection of EBV and Helicobacter pylori (HP) is unclear. This study focused on these issues.

METHODS

In this study, we detected the serum levels of PGI, PGII, anti-HP (immunoglobulin G) IgG antibodies and EBV DNA load in a total of 189 gastric cancer patients confirmed to be EBV positive or negative in tissue using in situ hybridization of EBV-encoded small RNAs (EBERs).

RESULTS

Compared to 123 EBV negative gastric cancer patients, the 66 patients infected with EBV exhibited significant higher levels of PGI and PGI/II ratio and meanwhile, had remarkably lower levels of anti-HP IgG. The prevalence of HP infection in EBV positive patients was 13.6%, and 52.8% in EBV negative patients. In subsequent analysis concerning the EBV DNA load, the patients were divided into two groups by a cutoff value of 1000 copies/ml. The EBV DNA load showed highly consistent association with PGI, PGI/II ratio and HP.

CONCLUSIONS

EBV infection in situ increased the serum levels of PGI and ratio of PGI/PGII in gastric cancer patients. Moreover, the EBV infection exclusively exists with HP infection in the patients with gastric cancer.

Gene identification for risk of relapse in stage I lung adenocarcinoma patients: a combined methodology of gene expression profiling and computational gene network analysis

Risk assessment and treatment choice remains a challenge in early non-small-cell lung cancer (NSCLC). The aim of this study was to identify novel genes involved in the risk of early relapse (ER) compared to no relapse (NR) in resected lung adenocarcinoma (AD) patients using a combination of high throughput technology and computational analysis. We identified 18 patients (n.13 NR and n.5 ER) with stage I AD. Frozen samples of patients in ER, NR and corresponding normal lung (NL) were subjected to Microarray technology and quantitative-PCR (Q-PCR). A gene network computational analysis was performed to select predictive genes. An independent set of 79 ADs stage I samples was used to validate selected genes by Q-PCR.From microarray analysis we selected 50 genes, using the fold change ratio of ER versus NR. They were validated both in pool and individually in patient samples (ER and NR) by Q-PCR. Fourteen increased and 25 decreased genes showed a concordance between two methods. They were used to perform a computational gene network analysis that identified 4 increased (HOXA10, CLCA2, AKR1B10, FABP3) and 6 decreased (SCGB1A1, PGC, TFF1, PSCA, SPRR1B and PRSS1) genes. Moreover, in an independent dataset of ADs samples, we showed that both high FABP3 expression and low SCGB1A1 expression was associated with a worse disease-free survival (DFS).Our results indicate that it is possible to define, through gene expression and computational analysis, a characteristic gene profiling of patients with an increased risk of relapse that may become a tool for patient selection for adjuvant therapy.

The potential value of serum pepsinogen for the diagnosis of atrophic gastritis among the health check-up populations in China: a diagnostic clinical research

BACKGROUND

The aim of this study is to assess the validity of the measurement of pepsinogen as a screening test for chronic atrophic gastritis (AG) in health check-up populations in China.

METHODS

Patients from consecutive regular health check-up were enrolled from January 2014 to June 2015. Endoscopy, combined with monitoring the Helicobacter pylori (Hp) infections, and measuring the serum pepsinogen (PG) were used to determine the diagnostic accuracy of PG for the screening of atrophic gastritis. Histopathology was assessed by the Operative Link on Gastritis Assessment (OLGA) system. Statistical analysis was performed using SPSS statistical software.

RESULTS

The total Hp infection rate was 40%. Based on pathology, the 996 participants were divided into three groups: non-atrophic (NAG), mild-moderate atrophic (MAG): stage I and II of the OLGA classification, and severe atrophic (SAG): stage III and IV of the OLGA classification. Compared with NAG and MAG groups, PGR decreased significantly in SAG group (p < 0.05). PGI and PGII levels were significantly elevated in Hp-positive group, while the PGR was markedly decreased (p < 0.01). When MAG and SAG groups were combined and compared with NAG group, the best cutoff value for atrophy diagnosis was PGI ≤50.3 ng/ml; the cutoff value in Hp-negative group was absolutely higher than in Hp-positive group. When NAG and MAG groups were combined and compared with the SAG group, the best cutoff value for diagnosis of severe atrophy was at PGR ≤4.28. The cutoff values in Hp-negative and Hp-positive groups were calculated at PGR ≤6.28 and ≤4.28, respectively.

CONCLUSIONS

Pepsinogens play an important role in the identification of patients with atrophic gastritis and severe AG. Use of different cutoff values of PG for Hp-negative and Hp-positive groups may offer greater efficacy in the diagnosis of AG.

A magnetic nanoparticle-labeled immunoassay with europium and samarium for simultaneous quantification of serum pepsinogen I and II

OBJECTIVE

To develop a novel immunoassay for the simultaneous determination of serum pepsinogen I (PG I) and pepsinogen II (PG II) by combining established methods of time-resolved fluoroimmunoassay (TRFIA) and magnetic nanoparticles separation.

MATERIALS AND METHODS

This new immunoassay method was characterised by immobilising primary antibodies on the surface of magnetic particles and labelled with stable fluorescent chelates of europium and samarium.

RESULTS

Using magnetic nanoparticles, the TRFIA immunoassay exhibited broad dynamic assay ranges for PG I with detection limit of 0.33 ng/mL, while for PG II with detection limit of 0.38 ng/mL. Cross-reactivity between PGs I and II were <15. The intra- and inter-assay coefficient variations of the method were <3%, and the recoveries were in the range of 97-103% for serum samples. Bland-Altman analysis of 124 serum samples showed good consistency with a commercial TRFIA kit. For PG I, the mean (95% confidence interval) difference was 0.97 (-14.3-12.3) ng/mL, whilst for PG II the difference was 0.6 (-4.4-3.2) ng/mL.

CONCLUSIONS

Our data suggest that the method is feasible and could be developed into a platform for the routine clinical determination of PG I and PG II levels in human serum.

Gastric mucosal status in populations with a low prevalence of Helicobacter pylori in Indonesia

In Indonesia, endoscopy services are limited and studies about gastric mucosal status by using pepsinogens (PGs) are rare. We measured PG levels, and calculated the best cutoff and predictive values for discriminating gastric mucosal status among ethnic groups in Indonesia. We collected gastric biopsy specimens and sera from 233 patients with dyspepsia living in three Indonesian islands. When ≥5.5 U/mL was used as the best cutoff value of Helicobacter pylori antibody titer, 8.6% (20 of 233) were positive for H. pylori infection. PG I and II levels were higher among smokers, and PG I was higher in alcohol drinkers than in their counterparts. PG II level was significantly higher, whereas PG I/II ratios were lower in H. pylori-positive than in H. pylori-negative patients. PG I/II ratios showed a significant inverse correlation with the inflammation and atrophy scores of the antrum. The best cutoff values of PG I/II were 4.05 and 3.55 for discriminating chronic and atrophic gastritis, respectively. PG I, PG II, and PG I/II ratios were significantly lower in subjects from Bangli than in those from Makassar and Surabaya, and concordant with the ABC group distribution; however, group D (H. pylori negative/PG positive) was the lowest in subjects from Bangli. In conclusion, validation of indirect methods is necessary before their application. We confirmed that serum PG level is a useful biomarker determining chronic gastritis, but a modest sensitivity for atrophic gastritis in Indonesia. The ABC method should be used with caution in areas with a low prevalence of H. pylori.

Link between Serum Pepsinogen Concentrations and Upper Gastrointestinal Endoscopic Findings

The serum pepsinogen (PG) assay findings are correlated with the status of Helicobacter pylori infection, but there are controversies on the link with upper gastrointestinal (UGI) endoscopic findings. The aim of this study was to determine the significance of a serum PG assay for correlating with endoscopic findings in H. pylori-seroprevalent adult population. Korean adults who visited for a health check-up were included consecutively. Subjects after gastrectomy or H. pylori eradication were excluded. After completing the serum PG assay and anti-H. pylori immunoglobulin G (IgG) titer on the same day of UGI endoscopy, subjects with equivocal serology test finding or gastric neoplasm were excluded. Of the 4,830 included subjects, 3,116 (64.5%) were seropositive for H. pylori. Seropositive finding was related to high serum PG I (P < 0.001) and PG II (P < 0.001) concentrations, low PG I/II ratio (P < 0.001), old age (P < 0.001), and male gender (P = 0.006). After adjusting age and gender, the serum PG I and II concentrations were positively correlated with the presence of nodular gastritis (NG) (all P = 0.003). The serum PG I was positively correlated with gastric ulcer (P = 0.003), and it was correlated with duodenal ulcer in seropositive subjects (P = 0.008). The PG I/II ratio was positively correlated with erosive esophagitis, while it was inversely related to chronic atrophic gastritis and metaplastic gastritis (all P < 0.001). Our findings suggest that the serum PG assay finding correlates well with the UGI endoscopic finding. A higher serum PG concentration in subjects with NG and peptic ulcer disease suggests that endoscopic findings reflect gastric secreting ability.

Evaluation of Pepsinogen I as a Biomarker of Drug-induced Gastric Mucosal Injury in Cynomolgus Monkeys

Gastric mucosal injury is frequently observed in nonclinical studies of nonhuman primates. Because microscopic evaluation of stomach is generally a terminal procedure, our objective was to determine whether serum pepsinogen I (PG I) could serve as a noninvasive biomarker for detection of gastric mucosal injury in monkey. Serum PG I was measured using a commercial human immunoassay in cynomolgus monkeys ( n = 166) prior to dosing and/or terminally in 11 studies of up to 1 month duration. Mean ( SD) PG I values (ug/L) for monkeys with ( n = 59) and without ( n = 100) gastric mucosal degeneration were 101 (215) and 28 (12.6), respectively. For monkeys with baseline and terminal PG I data, mean ( SD) fold change (ratio of terminal to baseline PG I) for monkeys with ( n = 57) and without ( n = 76) glandular degeneration were 4.1 (11.3) and 1 (0.28). Receiver operating characteristic area under the curve (AUC) data demonstrated moderate diagnostic accuracy for serum PG I for glandular degeneration, AUC ( SE) 0.789 (0.04), with improved diagnostic accuracy as a fold change of baseline, AUC ( SE) 0.816 (0.04), consistent with the large interindividual but low intraindividual variability of serum PG I values in control monkeys. These data demonstrate that serum PG I is a useful biomarker of drug-induced gastric mucosal injury in the cynomolgus monkey.

Gastritis and Gastric Ulcers in Working Dogs

Gastritis and gastric ulcers are an important cause of morbidity and mortality in canine athletes. Although the majority of scientific work on this condition has been performed in ultraendurance racing sled dogs, this condition has been identified in other canine athletes, including sled dogs competing in shorter events and dogs performing off-leash explosive detection duties. The cause of the syndrome is unknown, but current hypotheses propose a link between exercise-induced hyperthermia and loss of gastric mucosal barrier function as an early event in the pathogenesis. Treatment is focused on prevention of clinical disease using acid secretion inhibitors, such as omeprazole, which has excellent efficacy in controlled clinical studies.

Acute effects of coffee consumption on self-reported gastrointestinal symptoms, blood pressure and stress indices in healthy individuals

Background

It has been suggested that coffee may affect the gut-brain axis with conflicting outcomes. Moreover, there is insufficient evidence to determine whether the type or temperature of coffee consumed will have a different impact on the gut-brain axis. The purpose of this study was to investigate the effects of acute coffee consumption on the following: 1. self-reported GI symptoms and salivary gastrin, 2. stress indices [salivary cortisol and alpha-amylase (sAA)] and psychometric measures, and 3. blood pressure (BP), in healthy, daily coffee consuming individuals in non-stressful conditions.

Methods

This was a randomized, double blind, crossover clinical trial, in which 40 healthy individuals (20 men, 20 women), 20–55 years of age, randomly consumed four 200 ml coffee beverages containing 160 mg caffeine (hot and cold instant coffee, cold espresso, hot filtered coffee), 1 week apart. Salivary samples and psychometric questionnaires were collected at baseline and post-coffee consumption at 15,30, and 60 min for salivary gastrin and sAA measurements and at 60,120, and 180 min for cortisol measurements. BP was measured at beginning and end of each intervention. ClinicalTrials.gov ID: NCT02253628

Results

Coffee consumption significantly increased sAA activity (P = 0.041), with significant differences only between cold instant and filter coffee at 15 and 30 min post-consumption (P < 0.05). Coffee temporarily increased salivary gastrin, without differences between coffee types. Coffee did not affect salivary cortisol or self-reported anxiety levels. Coffee consumption significantly increased BP, within the healthy physiological levels, in a gender specific manner at the end of the experimental periods, without differences between coffee types.

Conclusion

Acute coffee consumption in non-stressful conditions activated sAA and BP but not salivary cortisol, indicating activation of the sympathetic nervous system. Post-coffee sAA increase without a concomitant cortisol increase may also indicate that coffee may have some anti-stress properties.

Effect of exercise on gastric health in field retrievers

Exercise-induced gastrointestinal disease (EIGD) has been reported in all domestic athletes. In dogs and humans, EIGD is most commonly associated with ultra-endurance racing sled dogs and marathon/triathlon competitors, respectively, suggesting that the syndrome is specifically a function of prolonged exercise. However, EIGD is also common in horses that exercise for brief periods, and more recently, EIGD has been identified in Labrador retrievers that perform off-leash explosive detection patrols. In this study, we tested the hypothesis that EIGD could be induced in retrievers performing competition-style retrieves. Gastric endoscopy and histopathological examination of gastric biopsies were performed on 10 healthy retrievers before and 24 h after a series of multi-set retrieves totalling over 5 km. Although the exercise challenge resulted in a small but statistically significant increase in gastric endoscopy severity score, it did not result in a higher prevalence of clinically-significant gastric disease or changes in gastric histopathology. We conclude that competitive retrieving is unlikely to induce clinically-significant gastric disease in healthy dogs.

Method evaluation of pepsinogen I/II assay based on chemiluminescent immunoassays and comparison with other test methods

BACKGROUND

Serum pepsinogen (PG) I and the PG I/PG II ratio have been used for atrophic gastritis (AG) diagnosis for decades. Low levels of PG I and/or PG I/PG II are closely related to AG and predict the risk of gastric cancer. We evaluated the performance of the chemiluminescent immunoassay-based Architect Pepsinogen I/II assay.

METHODS

The evaluation consisted of determination of the precision, linearity, limit of blank (LoB), limit of detection (LoD) and method comparison with Eiken and Biohit assays.

RESULTS

The total CVs were below 5% for both PG I and PG II. Acceptable linearity was observed for PG I and PG II in their respective reportable ranges. The PG I LoB was 0.317ng/mL and the PG II LoB was 0.418ng/mL, and LoDs were 0.412ng/mL and 0.497ng/mL, respectively. Correlation analysis indicated that results of the Architect assay were comparable to those of the Eiken and Biohit assays, but the three methods lead to different estimations of the cancer risk.

CONCLUSION

The overall analytical performance of Architect Pepsinogen I/II assay is acceptable for the detection of patients with suspected AG. The categorization results of gastric cancer risk showed some difference among test methods suggesting the need for harmonization among the methods from vendors.

Interaction Behavior Between Niclosamide and Pepsin Determined by Spectroscopic and Docking Methods

The interaction between niclosamide (NIC) and pepsin was investigated using multispectroscopic and molecular docking methods. Binding constant, number of binding sites, and thermodynamic parameters at different temperatures were measured. Results of fluorescence quenching and synchronous fluorescence spectroscopy in combination with three-dimensional fluorescence spectroscopy showed that changes occurred in the microenvironment of tryptophan residues and the molecular conformation of pepsin. Molecular interaction distance and energy-transfer efficiency between pepsin and NIC were determined based on Förster nonradiative energy-transfer mechanism. Furthermore, the binding of NIC inhibited pepsin activity in vitro. All these results indicated that NIC bound to pepsin mainly through hydrophobic interactions and hydrogen bonds at a single binding site. In conclusion, this study provided substantial molecular-level evidence that NIC could induce changes in pepsin structure and conformation.

Serum Indicators Reflecting Gastric Function May Also Correlate with Other Extragastric Diseases

Aim. Serological indicators of organ function can reveal intrinsic links between different organs. The present study aimed to determine the correlations of serum indicators for gastric and extragastric function. Methods. A total of 823 individuals were enrolled. Data on indicators reflecting blood lipids, blood glucose, indexes of stomach, kidney, liver, and thyroid function, and H. pylori IgG antibody level were collected. Results. As creatine (Cr) levels increased, PGI (pepsinogen I), PGII concentrations, and PGI/II ratio increased monotonically from 79.7 to 105.15 µg/L, 6.5 to 8.4 µg/L, and 11.97 to 12.27, respectively (P < 0.05). As thyroid peroxidase antibody (TPOAb) levels increased, PGI level decreased from 100.85 to 84 µg/L (P < 0.05) and as thyroid stimulating hormone (TSH) increased, PGI/II ratio increased monotonically from 11.54 to 12.68 (P < 0.05). As triglyceride (TG) levels increased, gastrin 17 (G17) concentrations increased monotonically from 1.73 to 2.7 pmol/L (P < 0.05). As serum glucose and glycated hemoglobin (HbA1C) increased, PGI/II concentrations increased monotonically from 11.98 to 12.67 and 9.7 to 13.54 (P < 0.05), respectively. Conclusions. Serum PG and G17 levels were associated with blood glucose and lipids, kidney function, and thyroid function but not with liver function. Serum indicators reflecting gastric function may correlate not only with primary diseases, but also with other extragastric diseases.

Motilin stimulates pepsinogen secretion in Suncus murinus

Motilin and ghrelin are gastrointestinal hormones that stimulate the migrating motor complex (MMC) of gastrointestinal motility during the fasting state. In this study, we examined the effect of motilin and ghrelin on pepsinogen secretion in anesthetized suncus (house musk shrew, Suncus murinus), a ghrelin- and motilin-producing mammal. By using a gastric lumen-perfusion system, we found that the intravenous administration of carbachol and motilin stimulated pepsinogen secretion, the latter in a dose-dependent manner, whereas ghrelin had no effect. We then investigated the pathways of motilin-induced pepsinogen secretion using acetylcholine receptor antagonists. Treatment with atropine, a muscarinic acetylcholine receptor antagonist, completely inhibited both carbachol and motilin-induced pepsinogen secretion. Motilin-induced pepsinogen secretion was observed in the vagotomized suncus. This is the first report demonstrating that motilin stimulates pepsinogen secretion, and suggest that this effect occurs through a cholinergic pathway in suncus.

Novel non-invasive biomarkers that distinguish between benign prostate hyperplasia and prostate cancer

BACKGROUND

The objective of this study was to discover and to validate novel noninvasive biomarkers that distinguish between benign prostate hyperplasia (BPH) and localized prostate cancer (PCa), thereby helping to solve the diagnostic dilemma confronting clinicians who treat these patients.

METHODS

Quantitative iTRAQ LC/LC/MS/MS analysis was used to identify proteins that are differentially expressed in the urine of men with BPH compared with those who have localized PCa. These proteins were validated in 173 urine samples from patients diagnosed with BPH (N = 83) and PCa (N = 90). Multivariate logistic regression analysis was used to identify the predictive biomarkers.

RESULTS

Three proteins, β2M, PGA3, and MUC3 were identified by iTRAQ and validated by immunoblot analyses. Univariate analysis demonstrated significant elevations in urinary β2M (P < 0.001), PGA3 (P = 0.006), and MUC3 (P = 0.018) levels found in the urine of PCa patients. Multivariate logistic regression analysis revealed AUC values ranging from 0.618 for MUC3 (P = 0.009), 0.625 for PGA3 (P < 0.008), and 0.668 for β2M (P < 0.001). The combination of all three demonstrated an AUC of 0.710 (95% CI: 0.631 - 0.788, P < 0.001); diagnostic accuracy improved even more when these data were combined with PSA categories (AUC = 0.812, (95% CI: 0.740 - 0.885, P < 0.001).

CONCLUSIONS

Urinary β2M, PGA3, and MUC3, when analyzed alone or when multiplexed with clinically defined categories of PSA, may be clinically useful in noninvasively resolving the dilemma of effectively discriminating between BPH and localized PCa.

Polymorphic rs9471643 and rs6458238 upregulate PGC transcription and protein expression in overdominant or dominant models

The pepsinogen C (PGC) gene encodes a major differentiation biomarker for gastric mucosa and has two single nucleotide polymorphisms, rs9471643 G>C and rs6458238 G>A, within its 5' upstream region that are involved in gastric carcinogenesis. However, in what genetic models the two polymorphisms modulate disease risk and how they relate to gastric carcinogenesis needs further study. We fitted the most appropriate genetic models to the PGC polymorphisms and validated their robustness; then with knowledge of the genetic model, we investigated the influence of functional variant alleles or genotypes on gene expression in vitro and in vivo. We confirmed that rs9471643 CG genotype was stably associated with reduced gastric cancer risk in complete overdominant model. This favorable CG genotype was also associated with reduced atrophic gastritis risk in subjects carrying rs6458238 AG/AA genotype. The G>C transition at rs9471643 enhanced promoter activity and transcription factor binding ability, and the CG genotype was consistently associated with elevated levels of PGC mRNA, in situ protein and serum protein in complete overdominant model based-analyses. Additionally, rs6458238 AG/AA genotype was associated with reduced atrophic gastritis risk in dominant model. Its favorable A allele was related to higher promoter activity and lower transcription factor binding ability, and the AG/AA genotype showed association with elevated levels of serum PGC protein in dominant model based-analyses. Our results suggest that rs9471643 CG and rs6458238 AG/AA genotypes have important roles in up-regulating PGC expression, which may partially explain why individuals with these favorable genotypes have decreased risks of getting gastric cancer.