Autoimmune atrophic gastritis is an immune-mediated disease resulting in autoimmune destruction of the specialized acid-producing gastric parietal cells. As a consequence, in autoimmune atrophic gastritis, gastric acid secretion is irreversibly impaired, and the resulting hypochlorhydria leads to the main clinical manifestations and is linked, directly or indirectly, to the long-term neoplastic complications of this disease. In the last few years, autoimmune atrophic gastritis has gained growing interest leading to the acquisition of new knowledge on different aspects of this disorder. Although reliable serological biomarkers are available and gastrointestinal endoscopy techniques have substantially evolved, the diagnosis of autoimmune atrophic gastritis is still affected by a considerable delay and relies on histopathological assessment of gastric biopsies. One of the reasons for the diagnostic delay is that the clinical presentations of autoimmune atrophic gastritis giving rise to clinical suspicion are very different, ranging from hematological to neurological–psychiatric up to gastrointestinal and less commonly to gynecological–obstetric symptoms or signs. Therefore, patients with autoimmune atrophic gastritis often seek advice from physicians of other medical specialties than gastroenterologists, thus underlining the need for increased awareness of this disease in a broad medical and scientific community.

Autoimmune atrophic gastritis (AAG) is an immune-mediated disorder affecting the gastric oxyntic mucosa. Two pathogenetic models are proposed: a pure autoimmune disorder or gastric autoimmunity triggered by Helicobacter pylori (Hp)-infection. In AAG, histological diagnosis of Hp may be challenging and serology can help assess exposure to Hp-infection. This study aimed to determine seroreactivity to Hp-antigens in AAG patients by using Hp-multiplex serology assay. A single-centre case-control study on 178 adults: 75 patients with serological and histological AAG diagnosis, 25 controls with histologically Hp-positive-non-atrophic gastritis (Ctr-NAG-Hp+) and 78 subjects with a healthy stomach (Ctr-HS). Sera were analysed using Hp-multiplex serology assay allowing simultaneous detection of antibodies to 13 Hp-proteins. Overall positivity cutoff: seroreactivity to more than 3 Hp-antigens. The number of seroreactive Hp-antigens was higher in AAG than in Ctr-HS(mean±SEM 2.2±0.3 vs 1.4±0.22,p=0.02) and lower than in Ctr-NAG-Hp+ patients (mean±SEM 5.4±0.5,p<0.001).Overall Hp-seropositivity in AAG was two-fold higher than in Ctr-HS but not statistically significant (21.1% vs 10.3%,p=0.06) and lower than in Ctr-NAG-Hp+(80%,p50% of AAG patients. By Hp-multiplex serology, 30% of histologically Hp-negative AAG pts had no seroreactivity, likely belonging to the pure AAG type. Conversely, 20% of AAG pts showed Hp exposure, indicating that infection might have triggered gastric autoimmunity. The remaining AAG patients showed seroreactivity below cut-off for seropositivity and thus not definitively categorisable by this approach.

Autoimmune gastritis (AIG) in its advanced atrophic stage is characterized by reduced acid secretion, dysbiosis, and gastric cancer (GC) risk. Swallowed oral bacteria surviving in increased intragastric pH may play a carcinogenic role. Oral microbiota was linked to increased GC risk. In AIG, the concomitant assessment of oral and gastric microbiota has not yet been performed. This study aimed to investigate the oral and gastric microbiota in AIG patients to clarify the role of oral bacteria in gastric dysbiosis. A case–control study on n = 20 histologically diagnosed AIG patients and n = 20 controls without AIG is conducted. Saliva samples were obtained from subjects who were fasting and without toothbrushing. Within 1 h, gastroscopy with biopsies (for histopathology and DNA extraction) was performed. Saliva (n = 40) and biopsy (n = 40) samples were frozen at −20 °C. DNA was extracted and prepared; paired-end sequencing was performed (IlluminaMiSeq-sequencer, San Diego, CA, USA). Bacterial abundance in biopsies was higher in AIG than in controls (p = 0.06), but was not different in the saliva (p = 0.54) samples. In biopsies, AIG showed a lower Shannon-Index than controls (p = 0.001). In saliva studies, AIG showed a higher Shannon-Index than controls (p = 0.0). In biopsies, Streptococcus oralis, Fusobacterium pseudoperiodonticum, Veillonella rogosae, and Gemella sanguinis were more frequent in AIG (p < 0.03). The most abundantly shared taxa between saliva and biopsy were S. oralis and Prevotella histicola; Gemella sanguinis, Fusobacterium pseudoperidonticum, and Veillonella rogosae were shared in AIG patients only. This study confirmed gastric dysbiosis in AIG. Oral taxa were more commonly associated with AIG and shared between the mouth and the stomach. In AIG, the oral microbiota is associated with gastric dysbiosis, highlighting the importance of oral eubiosis in patients with impaired gastric acid secretion.

Background/Objectives: Autoimmune gastritis (AIG), celiac disease (CD), and gastric surgery (GS) often cause iron deficiency anemia (IDA) due to iron malabsorption. In this clinical context, IDA treatment is often challenging. The first-line IDA treatment is oral iron supplementation followed by intravenous (IV) iron administration when ineffective or not tolerated. Ferric carboxymaltose (FCM) showed efficacy in various clinical settings. Prospective data evaluating the efficacy of IV FCM in IDA patients secondary to iron malabsorption are scant. The aim of the current study was to assess the tolerability, efficacy, and QoL impact of IV FCM for the treatment of IDA patients with iron malabsorption. Methods: Study design: single-center, prospective observational study: n = 37 adults with AIG, CD, or GS with IDA receiving IV FCM were consecutively included. Endpoints were (i) safety tolerability, (ii) efficacy on IDA recovery (Hb normalization), and (iii) QoL impact. At baseline (T0) and 12 weeks after treatment (T12), a QoL-SF12 questionnaire was assessed. Complete blood count (CBC) and iron status (ferritin, iron, transferrin, transferrin saturation (TS)) were assessed at T0, 4 weeks (T4), and T12 after treatment. Results: Of the 37 IDA patients, 19 (51.4%) had AIG, 9 (24.3%) CD, and 9 (24.3%) GS; Based on Ganzoni’s formula, 24 (64.9%) patients received a single IV FCM infusion (mean ± SEM dosage of 975 ± 12 mg); 13 (35.1%) required two IV infusion sessions with a mean ± SEM cumulative dose of 1400 ± 77 mg. One patient (2.7%) experienced mild adverse events without need for treatment interruption or hospitalization. At T0, anemia was moderate in 7 (18.9%) patients and severe in 1 (2.7%). IDA recovery was achieved in 26 (70.3%) patients at T4 and in 29 (78.4%) at T12. At T4, mean ± SEM Hb increased from 10.8 ± 0.2 g/dL to 12.7 ± 0.1 g/dL, ferritin from 28.5 ± 11.2 ng/mL to 188.2 ± 25.7 ng/mL, and TS from 6.7 ± 0.5% to 23.7 ± 1.9% (p < 0.0001). At T12, mean ± SEM Hb further increased to 13.1 ± 0.2 g/dL (p < 0.05 vs. T4), ferritin slightly decreased to 125 ± 26.7 ng/mL, and TS to 22.7 ± 2.8%. At T12, nonsignificant increases in QoL scores relative to baseline were observed. Conclusions: IV FCM is a safe and effective treatment leading to IDA recovery in nearly 80% of patients at T12. Thus, when oral iron treatment is not feasible or has failed, IV FCM treatment might be considered a first-line therapeutic option for IDA consequent to iron malabsorption.