Adherence of Helicobacter pylori to inflamed gastric mucosa is dependent on the sialic acid–binding adhesin (SabA) and cognate sialylated/fucosylated glycans on the host cell surface. By in situ hybridization, H. pylori bacteria were observed in close association with erythrocytes in capillaries and post-capillary venules of the lamina propria of gastric mucosa in both infected humans and Rhesus monkeys. In vivo adherence of H. pylori to erythrocytes may require molecular mechanisms similar to the sialic acid–dependent in vitro agglutination of erythrocytes (i.e., sialic acid–dependent hemagglutination). In this context, the SabA adhesin was identified as the sialic acid–dependent hemagglutinin based on sialidase-sensitive hemagglutination, binding assays with sialylated glycoconjugates, and analysis of a series of isogenic sabA deletion mutants. The topographic presentation of binding sites for SabA on the erythrocyte membrane was mapped to gangliosides with extended core chains. However, receptor mapping revealed that the NeuAcα2–3Gal-disaccharide constitutes the minimal sialylated binding epitope required for SabA binding. Furthermore, clinical isolates demonstrated polymorphism in sialyl binding and complementation analysis of sabA mutants demonstrated that polymorphism in sialyl binding is an inherent property of the SabA protein itself. Gastric inflammation is associated with periodic changes in the composition of mucosal sialylation patterns. We suggest that dynamic adaptation in sialyl-binding properties during persistent infection specializes H. pylori both for individual variation in mucosal glycosylation and tropism for local areas of inflamed and/or dysplastic tissue.

Summary The Helicobacter pylori adhesin BabA binds mucosal ABO/Leb blood group (bg) carbohydrates. BabA facilitates bacterial attachment to gastric surfaces, increasing strain virulence and forming a recognized risk factor for peptic ulcers and gastric cancer. High sequence variation causes BabA functional diversity, but the underlying structural-molecular determinants are unknown. We generated X-ray structures of representative BabA isoforms that reveal a polymorphic, three-pronged Leb binding site. Two diversity loops, DL1 and DL2, provide adaptive control to binding affinity, notably ABO versus O bg preference. H. pylori strains can switch bg preference with single DL1 amino acid substitutions, and can coexpress functionally divergent BabA isoforms. The anchor point for receptor binding is the embrace of an ABO fucose residue by a disulfide-clasped loop, which is inactivated by reduction. Treatment with the redox-active pharmaceutic N-acetylcysteine lowers gastric mucosal neutrophil infiltration in H. pylori-infected Leb-expressing mice, providing perspectives on possible H. pylori eradication therapies.

Background and purpose The aim of this study was to investigate utilization rates, treatment pathways and survival prognosis in patients with amyotrophic lateral sclerosis (ALS) undergoing non‐invasive (NIV) and tracheostomy invasive ventilation (TIV) in a real‐world setting. Methods A prospective cohort study using a single‐centre register of 2702 ALS patients (2007 to 2019) was conducted. Utilization of NIV/TIV and survival data were analysed in three cohorts: (i) non‐NIV; (ii) NIV (NIV without subsequent TIV); and (iii) TIV (including TIV preceded by NIV). Results A total of 1720 patients with available data were identified, 72.0% of whom (n = 1238) did not receive ventilation therapy. NIV was performed in 20.8% of patients (n = 358). TIV was performed in 9.5% of patients (n = 164), encompassing both primary TIV (7.2%, n = 124) and TIV with preceding NIV (2.3%, n = 40). TIV was more often utilized without previous NIV (25.7% vs. 8.3% of all ventilated patients), demonstrating that primary TIV was the prevailing pathway for invasive ventilation. The median (range) survival was significantly longer in the NIV cohort (40.8 [37.2–44.3] months) and the TIV cohort (82.1 [68.7–95.6] months) as compared to the non‐NIV cohort (33.6 [31.6–35.7] months). Conclusions Although NIV represents the standard of care, its utilization rate was low. TIV was mainly started without preceding NIV, suggesting that TIV may not be confined to NIV treatment escalation. However, TIV was pursued in a minority of patients who had previously undergone NIV. The survival benefit observed in the patients with NIV was equal to that reported in a controlled pivotal trial, but the prognosis with TIV is highly variable. The determinants of utilization of NIV/TIV and of survival (bulbar syndrome, availability of ventilation‐related home nursing, cultural factors) warrant further investigation.

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