Predictive factors for improvement of atrophic gastritis and intestinal metaplasia after Helicobacter pylori eradication: a three-year follow-up study in Korea

Background and Aims: To date, data on the effects of anti‐Helicobacter therapy on the improvement of atrophic gastritis (AG) and intestinal metaplasia (IM) have been conflicting. This study was performed to investigate whether eradication of H. pylori could lead to the improvement of AG and IM, and the prognostic factors associated with the improvement of AG and IM. Methods: Four hundred patients consisting of H. pylori‐negative (n = 116) and H. pylori‐positive (n = 284) groups were followed up 1 and 3 years after initial H. pylori tests. Serum levels of pepsinogen (PG), bacteria, environmental factors, and genetic polymorphisms were determined. Results: The grade of corpus atrophy decreased at 1 and 3 years after successful eradication (p < .001 and p = .033, respectively). However, there was no significant change in the IM in the antrum and in the corpus. Prediction factors for the improvement of corpus AG by H. pylori eradication were baseline low PG I/II ratio (≤3), high salt intake, and corpus‐predominant gastritis. IM improvement was also associated with spicy food intake and high baseline grade of IM, in addition to these factors. In addition, IL‐1B‐511 C/T and IL‐6‐572 C/G alleles were found to inhibit IM improvement. However, H. pylori‐negative and noneradicated group did not show any significant change in AG or IM. Conclusion: Corpus AG was reversed by H. pylori eradication, and improvement of IM by H. pylori eradiation was more definite in patients with severe IM, low PG I/II ratio, and corpus‐predominant gastritis, suggesting that H. pylori eradication is valuable even in severe cases.     

Cross Protection against Influenza A Virus by Yeast-Expressed Heterologous Tandem Repeat M2 Extracellular Proteins

The influenza M2 ectodomain (M2e) is well conserved across human influenza A subtypes, but there are few residue changes among avian and swine origin influenza A viruses. We expressed a tandem repeat construct of heterologous M2e sequences (M2e5x) derived from human, swine, and avian origin influenza A viruses using the yeast expression system. Intramuscular immunization of mice with AS04-adjuvanted M2e5x protein vaccines was effective in inducing M2e-specific antibodies reactive to M2e peptide and native M2 proteins on the infected cells with human, swine, or avian influenza virus, mucosal and systemic memory cellular immune responses, and cross-protection against H3N2 virus. Importantly, M2e5x immune sera were found to confer protection against different subtypes of H1N1 and H5N1 influenza A viruses in naïve mice. Also, M2e5x-immune complexes of virus-infected cells stimulated macrophages to secrete cytokines via Fc receptors, indicating a possible mechanism of protection. The present study provides evidence that M2e5x proteins produced in yeast cells could be developed as a potential universal influenza vaccine.     

Dynamic profiling of double-stranded RNA binding proteins

Double-stranded (ds) RNA is a key player in numerous biological activities in cells, including RNA interference, anti-viral immunity and mRNA transport. The class of proteins responsible for recognizing dsRNA is termed double-stranded RNA binding proteins (dsRBP). However, little is known about the molecular mechanisms underlying the interaction between dsRBPs and dsRNA. Here we examined four human dsRBPs, ADAD2, TRBP, Staufen 1 and ADAR1 on six dsRNA substrates that vary in length and secondary structure. We combined single molecule pull-down (SiMPull), single molecule protein-induced fluorescence enhancement (smPIFE) and molecular dynamics (MD) simulations to investigate the dsRNA-dsRBP interactions. Our results demonstrate that despite the highly conserved dsRNA binding domains, the dsRBPs exhibit diverse substrate specificities and dynamic properties when in contact with different RNA substrates. While TRBP and ADAR1 have a preference for binding simple duplex RNA, ADAD2 and Staufen1 display higher affinity to highly structured RNA substrates. Upon interaction with RNA substrates, TRBP and Staufen1 exhibit dynamic sliding whereas two deaminases ADAR1 and ADAD2 mostly remain immobile when bound. MD simulations provide a detailed atomic interaction map that is largely consistent with the affinity differences observed experimentally. Collectively, our study highlights the diverse nature of substrate specificity and mobility exhibited by dsRBPs that may be critical for their cellular function.     

Fine‐tuning of dual‐SMAD inhibition to differentiate human pluripotent stem cells into neural crest stem cells

ObjectivesThe derivation of neural crest stem cells (NCSCs) from human pluripotent stem cells (hPSCs) has been commonly induced by WNT activation in combination with dual‐SMAD inhibition.In this study, by fine‐tuning BMP signalling in the conventional dual‐SMAD inhibition, we sought to generate large numbers of NCSCs without WNT activation.Materials and methodsIn the absence of WNT activation, we modulated the level of BMP signalling in the dual‐SMAD inhibition system to identify conditions that efficiently drove the differentiation of hPSCs into NCSCs. We isolated two NCSC populations separately and characterized them in terms of global gene expression profiles and differentiation ability.ResultsOur modified dual‐SMAD inhibition containing a lower dose of BMP inhibitor than that of the conventional dual‐SMAD inhibition drove hPSCs into mainly NCSCs, which consisted of HNK⁺p75high and HNK⁺p75low cell populations. We showed that the p75high population formed spherical cell clumps, while the p75low cell population generated a 2D monolayer.We detected substantial differences in gene expression profiles between the two cell groups and showed that both p75high and p75low cells differentiated into mesenchymal stem cells (MSCs), while only p75high cells had the ability to become peripheral neurons.ConclusionsThis study will provide a framework for the generation and isolation of NCSC populations for effective cell therapy for peripheral neuropathies and MSC‐based cell therapy.     

The coffee diterpene kahweol induces heme oxygenase-1 via the PI3K and p38/Nrf2 pathway to protect human dopaminergic neurons from 6-hydroxydopamine-derived oxidative stress

In this study, we investigated the mechanisms of kahweol protection of neuronal cells from cell death induced by the Parkinson's disease-related neurotoxin 6-hydroxydopamine (6-OHDA). Pretreatment of SH-SY5Y cells with kahweol significantly reduced 6-OHDA-induced generation of ROS, caspase-3 activation, and subsequent cell death. Kahweol also up-regulated heme oxygenase-1 (HO-1) expression, which conferred neuroprotection against 6-OHDA-induced oxidative injury. Moreover, kahweol induced PI3K and p38 activation, which are involved in the induction of Nrf2, HO-1 expression, and neuroprotection. These results suggest that regulation of the anti-oxidant enzyme HO-1 via the PI3K and p38/Nrf2 signaling pathways controls the intracellular levels of ROS.     

Glycated albumin induces superoxide generation in mesangial cells.

BACKGROUND/AIMS: Reactive oxygen species are involved in the pathogenesis of diabetic nephropathy. Amadori-modified glycated albumin modulates signaling pathways in mesangial cells that contribute to the development of diabetic nephropathy. However, the effects of glycated albumin on mesangial cell superoxide (O2-) production are unknown. Thus, we examined whether glycated albumin induces mesangial cell O2- generation and whether increased O2- production elicits cell growth. METHODS: Quiescent human mesangial cells (HMC) were exposed to bovine serum albumin (BSA) or glycated BSA (Gly-BSA) with or without diphenylene iodonium (DPI) or apocynin, inhibitors of NAD(P)H oxidase, GF109203X (GFX), a protein kinase C (PKC) inhibitor. RESULTS: Gly-BSA increased PKC activity, particularly PKC-alpha and -alpha1, within 15 min of incubation with HMC, which decreased to the control value at 2 h. Gly-BSA incubated with HMC increased O2- production by 2 times vis-á-vis BSA-treated cells. The Gly-BSA-induced increased O2- generation was suppressed by DPI or GFX. Gly-BSA significantly increased mesangial [3H]-leucine incorporation, whereas these processes were abrogated by DPI, apocynin or GFX. CONCLUSIONS: Gly-BSA induces PKC/NAD(P)H oxidase-dependent O2- production in HMC, which in turn results in cell hypertrophy. Thus, O2- induced by glycated albumin might cause mesangial cell alterations in diabetes participating in the pathophysiology of diabetic nephropathy.     

Mono- and trivalent ions around DNA: a small-angle scattering study of competition and interactions

The presence of small numbers of multivalent ions in DNA-containing solutions results in strong attractive forces between DNA strands. Despite the biological importance of this interaction, e.g., DNA condensation, its physical origin remains elusive. We carried out a series of experiments to probe interactions between short DNA strands as small numbers of trivalent ions are included in a solution containing DNA and monovalent ions. Using resonant (anomalous) and nonresonant small angle x-ray scattering, we coordinated measurements of the number and distribution of each ion species around the DNA with the onset of attractive forces between DNA strands. DNA-DNA interactions occur as the number of trivalent ions increases. Surprisingly good agreement is found between data and size-corrected numerical Poisson-Boltzmann predictions of ion competition for non- and weakly interacting DNAs. We also obtained an estimate for the minimum number of trivalent ions needed to initiate DNA-DNA attraction.