Serum pepsinogen I and pepsinogen II, and the ratio of pepsinogen I/pepsinogen II in peptic ulcer diseases: with special emphasis on the influence of the location of the ulcer crater

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.

Marked decrease in serum pepsinogen II levels resulting from endoscopic resection of a large duodenal tumor

Studies have indicated that serum pepsinogen (PG) levels are not only markers for chronic atrophic gastritis but also predictive risk factors for gastric cancer. However, serum PG levels can change because of pathological conditions other than gastritis. We report the first case in which abnormally high serum PG II levels (168.8 ng/mL) led to the discovery of a large tumor covering a wide area in the duodenum, and after resection of the tumor, the serum PG II levels markedly decreased. Because endoscopic and histopathological examinations showed no indications of atrophic changes, inflammation of the gastric mucosa, or Helicobacter pylori infection, the serum PG II levels eventually returned to normal (10.1 ng/mL). The preoperative abnormally high PG II levels were probably caused by the large duodenal tumor that prevented PG II (which is produced by the duodenal Brunner’s glands) from being secreted into the lumen, a condition that increased the amount transferred to the bloodstream. No previous reports have investigated serum PG II levels before and after resection of a large duodenal tumor. We believe this case provides valuable insight regarding the dynamics of PG II in the body and has important diagnostic implications.

Serum pepsinogen II: a neglected but useful biomarker to differentiate between diseased and normal stomachs

BACKGROUND AND AIM

Serum pepsinogen II (sPGII) is underutilized and considered an inconspicuous biomarker in clinical practice. We refocused on this neglected but novel biomarker and conducted the present study, aiming to elucidate the normal level of sPGII in healthy Chinese patients and to investigate the clinical utility of sPGII for gastric disease screening.

METHODS

In 2008-2009, a total of 2022 participants from northern China were selected and enrolled in the study. sPGII and Helicobacter pylori (H. pylori)-immunoglobulin G were measured with ELISA.

RESULTS

sPGII showed a normal value of 6.6 microg/L in a total of 466 patients with endoscopically- and histologically-normal stomachs. A small sex difference was observed: the average value of sPGII was 7 microg/L and 6 microg/L in males and females, respectively (P < 0.001). In the differentiation between healthy and diseased (endoscopically-diseased stomach or gastritis/atrophic gastritis in endoscopic biopsies) stomach mucosae, the best sPGII cut-off value was 8.25 microg/L (sensitivity 70.6%, specificity 70.8%). In screening the H. pylori seropositivity, the optimum cut-off sPGII value was 10.25 microg/L (sensitivity 71.6%, specificity 70.1%).

CONCLUSIONS

We demonstrated that the mean values of sPGII in a healthy Chinese population are 7 microg/L and 6 microg/L for males and females, respectively. sPGII significantly increases in diseased and H. pylori-infected stomach, and the best sPGII cut-off value is 8.25 microg/L in the differentiation between patients with healthy and diseased stomach mucosae. Furthermore, Chinese patients with sPGII greater than 10.25 microg/L are at greater risk of various H. pylori-related gastropathies, and are therefore prior candidates for gastro-protection therapy.