Endocrine Abstracts

JOINT2118

Autoimmune atrophic gastritis (AAG) is an organ-specific autoimmune disease that is primarily asymptomatic in the early stages, and often the cause of these AAG cases is unclear. AAG exhibits vague clinical manifestations and is accompanied by the development of other autoimmune disorders and nutritional malabsorption. It has been proposed that gastric microbiota may have an essential impact on immunological processes within the gastric tissues. However, the changes in gastric microbial communities during AAG development and their potential impact on further AAG and gastric neuroendocrine tumor (GNET) development are still largely understudied.

Objectives: This study aimed to examine the gastric microbiome composition in gastric fluid samples, determine selenium, and neopterin concentrations in blood samples from patients with AAG, GNET, and healthy controls.

Materials and Methods: A total of 25 participants were included, comprising nine AAG patients, nine GNET patients, and seven control patients. Patients underwent esophagogastroduodenoscopy during which gastric fluid was collected. Bacterial DNA was extracted from gastric fluid samples using the Qiagen PowerFecal Pro Kit. Sequencing was performed on an Illumina MiSeq platform. Biochemical markers, such as selenium, and neopterin, were determined from blood samples.

Results: The study assessed microbial diversity and abundances across AAG, NET, and controls. Genera identified included Streptococcus, Rothia, Helicobacter, Actinomyces, Veillonella, and Prevotella. Significant changes were observed in four genera in AAG and six in NET, compared to controls. Compared to the control group, AAG patients showed the highest increase in Rothia abundance and the greatest reduction in Haemophilus. Similarly, in the NET group, Rothia also showed the highest increase, while Gemella exhibited the greatest reduction. The NET group was the most heterogeneous. Median plasma selenium levels were 97.17 ± 21.84 µg/l in AAG, 105.29 ± 21.15 µg/l in GNET, and 103.31 ± 29.09 µg/l in controls. Neopterin levels were 2.84 ± 0.48 ng/mL in AAG, 3.68 ± 1.58 ng/mL in GNET, and 2.95 ± 0.80 ng/mL in controls. No significant differences were observed in selenium or neopterin levels among groups.

Conclusions: Our data show that the number of identified species was similar across groups; however, significant changes were observed in the evenness metric of the identified species. Furthermore, differential abundance testing revealed that the Rothia genus exhibited the highest increase in both AAG and GNET groups compared to controls. No significant differences were found in biochemical markers. While this study provides initial findings, further research is essential to fully comprehend AAG and GNET. Funding:lzp-2022/1-0102.