PPIs are not effective in reducing GERD symptoms in infants. Placebo-controlled trials in older children are lacking. Although PPIs seem to be well tolerated during short-term use, evidence supporting the safety of PPIs is lacking.

The genus Octadecabacter is a member of the ubiquitous marine Roseobacter clade. The two described species of this genus, Octadecabacter arcticus and Octadecabacter antarcticus, are psychrophilic and display a bipolar distribution. Here we provide the manually annotated and finished genome sequences of the type strains O. arcticus 238 and O. antarcticus 307, isolated from sea ice of the Arctic and Antarctic, respectively. Both genomes exhibit a high genome plasticity caused by an unusually high density and diversity of transposable elements. This could explain the discrepancy between the low genome synteny and high 16S rRNA gene sequence similarity between both strains. Numerous characteristic features were identified in the Octadecabacter genomes, which show indications of horizontal gene transfer and may represent specific adaptations to the habitats of the strains. These include a gene cluster encoding the synthesis and degradation of cyanophycin in O. arcticus 238, which is absent in O. antarcticus 307 and unique among the Roseobacter clade. Furthermore, genes representing a new subgroup of xanthorhodopsins as an adaptation to icy environments are present in both Octadecabacter strains. This new xanthorhodopsin subgroup differs from the previously characterized xanthorhodopsins of Salinibacter ruber and Gloeobacter violaceus in phylogeny, biogeography and the potential to bind 4-keto-carotenoids. Biochemical characterization of the Octadecabacter xanthorhodopsins revealed that they function as light-driven proton pumps.

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BACKGROUND. Chronic hepatitis C virus (HCV) infection is characterized by a severe impairment of HCV-specific CD4 + T cell help that is driven by chronic antigen stimulation. We aimed to study the fate of HCV-specific CD4 + T cells after virus elimination. METHODS. HCV-specific CD4 + T cell responses were longitudinally analyzed using MHC class II tetramer technology, multicolor flow cytometry, and RNA sequencing in a cohort of patients chronically infected with HCV undergoing therapy with directacting antivirals. In addition, HCV-specific neutralizing antibodies and CXCL13 levels were analyzed. RESULTS. We observed that the frequency of HCV-specific CD4 + T cells increased within 2 weeks after initiating directacting antiviral therapy. Multicolor flow cytometry revealed a downregulation of exhaustion and activation markers and an upregulation of memory-associated markers. Although cells with a Th1 phenotype were the predominant subset at baseline, cells with phenotypic and transcriptional characteristics of follicular T helper cells increasingly shaped the circulating HCVspecific CD4 + T cell repertoire, suggesting antigen-independent survival of this subset. These changes were accompanied by a decline of HCV-specific neutralizing antibodies and the germinal center activity. CONCLUSION. We identified a population of HCV-specific CD4 + T cells with a follicular T helper cell signature that is maintained after therapy-induced elimination of persistent infection and may constitute an important target population for vaccination efforts to prevent reinfection and immunotherapeutic approaches for persistent viral infections.

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Esophageal multichannel intraluminal impedance (MII) allows measurement of the conductivity of adjacent contents. During esophageal rest, raw impedance levels may represent mucosal integrity. We assessed the influence of proton pump inhibitors (PPIs) on presumed mucosal integrity by reanalyzing raw MII levels of 21 pH-MII tracings from infants with gastroesophageal reflux (GER) disease before and after esomeprazole treatment. Median (interquartile range) esophageal MII increased during treatment, 938 (652-1304) versus 1885 (1360-2183) Ohm, P < 0.0001. Patients with lower MII levels demonstrated a larger increase on therapy: Spearman r2 = 0.28, P = 0.014. No correlation with standard GER parameters was observed. In conclusion, PPI therapy increases MII levels in infants with symptomatic GER disease.

The combined regulation of a network of inhibitory and activating T cell receptors may be a critical step in the development of chronic HCV infection. Ex vivo HCV MHC class I + II tetramer staining and bead-enrichment was performed with baseline and longitudinal PBMC samples of a cohort of patients with acute, chronic and spontaneously resolved HCV infection to assess the expression pattern of the co-inhibitory molecule TIGIT together with PD-1, BTLA, Tim-3, as well as OX40 and CD226 (DNAM-1) of HCV-specific CD4+ T cells, and in a subset of patients of HCV-specific CD8+ T cells. As the main result, we found a higher expression level of TIGIT+ PD-1+ on HCV-specific CD4+ T cells during acute and chronic HCV infection compared to patients with spontaneously resolved HCV infection (p < 0,0001). Conversely, expression of the complementary co-stimulatory receptor of TIGIT, CD226 (DNAM-1) was significantly decreased on HCV-specific CD4+ T cells during chronic infection. The predominant phenotype of HCV-specific CD4+ T cells during acute and chronic infection was TIGIT+, PD-1+, BTLA+, Tim-3−. This comprehensive phenotypic study confirms TIGIT together with PD-1 as a discriminatory marker of dysfunctional HCV-specific CD4+ T cells.

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