Coordinated regulation of phosphatidylinositol 4-phosphate and phosphatidylserine levels by Osh4p and Osh5p is an essential regulatory mechanism in autophagy.

Macroautophagy (hereafter autophagy) is an intracellular degradative pathway in budding yeast cells. Certain lipid types play essential roles in autophagy; yet the precise mechanisms regulating lipid composition during autophagy remain unknown. Here, we explored the role of the Osh family proteins in the modulating lipid composition during autophagy in budding yeast. Our results showed that osh1-osh7∆ deletions lead to autophagic dysfunction, with impaired GFP-Atg8 processing and the absence of autophagosomes and autophagic bodies in the cytosol and vacuole, respectively. Freeze-fracture electron microscopy (EM) revealed elevated phosphatidylinositol 4-phosphate (PtdIns(4)P) levels in cytoplasmic and luminal leaflets of autophagic bodies and vacuolar membranes in all deletion mutants. Phosphatidylserine (PtdSer) levels were significantly decreased in the autophagic bodies and vacuolar membranes in osh4∆ and osh5∆ mutants, whereas no significant changes were observed in other osh deletion mutants. Furthermore, we identified defects in autophagic processes in the osh4∆ and osh5∆ mutants, including rare autophagosome formation in the osh5∆ mutant and accumulation of autophagic bodies in the vacuole in the osh4∆ mutant, even in the absence of the proteinase inhibitor PMSF. These findings suggest that Osh4p and Osh5p play crucial roles in the transport of PtdSer to autophagic bodies and autophagosome membranes, respectively. The precise control of lipid composition in the membranes of autophagosomes and autophagic bodies by Osh4p and Osh5p represents an important regulatory mechanism in autophagy.

Case report: A pediatric case of repeated false-positive urea breath test for Helicobacter pylori without decreased gastric acid secretion.

The urea breath test (UBT) is often used to diagnose Helicobacter pylori infection and for its eradication. However, this text can give positive results even for other urease-active bacteria other than H. pylori. Even after the successful eradication of H. pylori, the presence of other urease-active bacteria in the gut and oral cavity can lead to positive UBT results in patients with decreased gastric acid secretion. Herein, a 15-year-old boy was diagnosed with H. pylori infection through the testing and treatment program for H. pylori for third-year junior high-school students in Saga Prefecture initiated in 2016. He underwent triple therapy comprising vonoprazan; however, UBT was found to be positive even after therapy. The results remained positive even after fourth-line eradication therapy. Stool antigen, PCR using gastric fluid, microscopy, culture, and rapid urease tests were all negative. Pepsinogen levels were normal, and none of the findings suggested autoimmune gastritis. Gastric microflora analysis revealed oral flora showing urease activity. UBT is considered useful for determining the successful eradication of H. pylori; however, it may give false-positive results for both H. pylori infection and eradication judgment. Although the patient did not have autoimmune gastritis or decreased gastric acid secretion, it is presumed that oral commensal bacteria showing urease activity inhabited the stomach, resulting in the persistently positive UBT results. In conclusion, repeated false-positive UBT results for H. pylori may occur even without gastric acid hyposecretion. If H. pylori eradication is unsuccessful based on UBT, additional test by stool H. pylori antigen tests should be considered.

Unique asymmetric distribution of phosphatidylserine and phosphatidylethanolamine in Toxoplasma gondii revealed by nanoscale analysis.

Toxoplasma gondii is a highly prevalent obligate apicomplexan parasite that is important in clinical and veterinary medicine. It is known that glycerophospholipids phosphatidylserine (PtdSer) and phosphatidylethanolamine (PtdEtn), especially their expression levels and flip-flops between cytoplasmic and exoplasmic leaflets, in the membrane of T. gondii play important roles in efficient growth in host mammalian cells, but their distributions have still not been determined because of technical difficulties in studying intracellular lipid distribution at the nanometer level. In this study, we developed an electron microscopy method that enabled us to determine the distributions of PtdSer and PtdEtn in individual leaflets of cellular membranes by using quick-freeze freeze-fracture replica labeling. Our findings show that PtdSer and PtdEtn are asymmetrically distributed, with substantial amounts localized at the luminal leaflet of the inner membrane complex (IMC), which comprises flattened vesicles located just underneath the plasma membrane (see Figs. 2B and 7). We also found that PtdSer was absent in the cytoplasmic leaflet of the inner IMC membrane, but was present in considerable amounts in the cytoplasmic leaflet of the middle IMC membrane, suggesting a barrier-like mechanism preventing the diffusion of PtdSer in the cytoplasmic leaflets of the two membranes. In addition, the expression levels of both PtdSer and PtdEtn in the luminal leaflet of the IMC membrane in the highly virulent RH strain were higher than those in the less virulent PLK strain. We also found that the amount of glycolipid GM3, a lipid raft component, was higher in the RH strain than in the PLK strain. These results suggest a correlation between lipid raft maintenance, virulence, and the expression levels of PtdSer and PtdEtn in T. gondii.

Efficacy and safety of vonoprazan-based regimen for Helicobacter pylori eradication therapy in Japanese adolescents: a prospective multicenter study.

BACKGROUND: Vonoprazan (VPZ)-based regimen for Helicobacter pylori (H. pylori) is safe and more efficacious than the proton pump inhibitor-based regimen mainly in adults. This study aimed to evaluate the efficacy and safety of a VPZ-based regimen for H. pylori eradication therapy in adolescents. METHODS: An H. pylori screening and treatment longitudinal project for third-year junior high school students in Saga Prefecture began in 2016. Students who tested positive for both urine and stool tests received a VPZ-based regimen. On the checklist, students were asked for diarrhea, fever, abdominal pain, nausea, vomiting, urticaria, dysgeusia, or bloody stool occurrence during the therapy. RESULTS: The longitudinal project for H. pylori screening and treatment among third-grade students in Saga Prefecture targeted 41,115 students from 2017 to 2021 and 836 as positive. Of the 645 students, 542 (84.0% in per protocol [PP] analysis and 73.6% in intention-to-treat [ITT] analysis) were successful in primary eradication therapy. The secondary eradication therapy was successful in 79 (96.3% in PP analysis and 76.7% in ITT analysis) of 82 students. In the primary eradication therapy, abdominal pain occurred in 164 (27.9%), diarrhea in 217 (36.9%), nausea or vomiting in 7 (1.2%), and urticaria in 13 (2.2%) students. In the secondary eradication therapy, abdominal pain occurred in 12 (19.4%) and diarrhea in 17 (27.4%) students. The eradication therapy of 5 students was interrupted due to adverse events only by primary eradication therapy. CONCLUSIONS: VPZ-based regimen for H. pylori was efficacious and safe for adolescents, as in adults, for both primary and secondary eradication therapies.

Essential roles of phosphatidylinositol 4-phosphate phosphatases Sac1p and Sjl3p in yeast autophagosome formation.

Autophagy is regulated by phosphoinositides. We have previously shown that phosphatidylinositol 4-phosphate (PtdIns(4)P) is localized in the autophagosomal membrane. Additionally, in yeast cells, phosphatidylinositol 4-kinases Pik1p and Stt4p play important roles in the formation of the autophagosome and its fusion with the vacuole, respectively. In this study, we analyzed the primary role of PtdIns(4)P phosphatases in yeast autophagy. The PtdIns(4)P labeling densities in the membranes of the vacuoles, mitochondria, nucleus, endoplasmic reticulum, and plasma membrane dramatically increased in the phosphatase deletion mutants sac1∆ and sjl3∆, and the temperature-sensitive mutant sac1ts/sjl3∆ at the restrictive temperature. GFP-Atg8 processing assay indicated defective autophagy in the sac1∆ and sac1ts/sjl3∆ mutants. In contrast to the localization of PtdIns(4)P in the luminal leaflet of autophagosomal membranes in the wild-type yeast, PtdIns(4)P was localized in both the luminal and cytoplasmic leaflets of the autophagosomal membranes in the sac1∆ strain. In addition, the number of autophagic bodies in the vacuole significantly decreased in the sac1∆ strain, although autophagosomes were present in the cytoplasm. In the sac1ts/sjl3∆ strain, the number of autophagosomes in the cytoplasm dramatically decreased at the restrictive temperature. Considering that the numbers of autophagosomes and autophagic bodies in the sjl3∆ strain were comparable to those in the wild-type yeast, we found that the autophagosome could not be formed when PtdIns(4)P phosphatase activities of both Sac1p and Sjl3p were diminished. Together, these results indicate that the turnover of PtdIns(4)P by phosphatases is essential for autophagosome biogenesis.

Selective increment of phosphatidylserine on the autophagic body membrane in the yeast vacuole.

In yeast cells, the autophagosome is a double-membrane structure; the inner membrane becomes the autophagic body membrane in the vacuole. Vacuolar enzymes degrade the autophagic body. There is no critical information regarding its selective degradation. Using the electron microscopy method, distributions of four phospholipids were examined in the autophagosomal and autophagic body membranes upon autophagy induction. The labeling of phosphatidylserine (PtdSer) in the autophagic body membrane dramatically increased after it converted from the autophagosome, but remained low in the vacuolar membrane. PtdSer in the autophagic body membrane also increased in atg15∆ yeast. These results suggest that the selective increment of PtdSer in the autophagic body, but not the vacuolar, membrane, can explain the selective degradation of the autophagic membrane.

Gastrointestinal adverse reactions reduce the success rate of Helicobacter pylori eradication therapy: A multicenter prospective cohort study.

BACKGROUND: The screening and treatment of Helicobacter pylori infection for all junior high students in Saga Prefecture, Japan, were started in 2016. The present study aims to evaluate the influence of adverse reactions on the success of the eradication therapy. METHODS: From 2017 to 2019, 25,006 third-grade junior high school students were tested for urinary anti-H. pylori antibodies. Positive cases were confirmed by H. pylori stool antigen tests. Of the 531 students who were found to be H. pylori-positive, 390 (358 in first-line and 32 in second-line therapy) underwent eradication therapy, and 274 (242 in first-line and 32 in second-line) students actually completed a self-reported form to rate stool consistency (based on the Bristol Stool Scale), the maximum number of bowel movements, and abdominal symptoms during the 7 days of treatment. RESULTS: Among the 274 students, the total of primary and secondary eradication success rates was 87% (95% confidential interval: 82.9-90.1) in intention-to-treat analysis. On days 4, 5, and 6, stool consistency was looser in the primary eradication failure group than in the success group (p < .05). Looser stool consistencies were observed in male students with abdominal pain compared to those who did not experience pain (p < .05). Abdominal pain and diarrhea were detected in 28.5% and 42.7% of the subjects, respectively. The overall incidence of other adverse events was low (n = 8/274, 2.9%), and only two students discontinued treatment because of adverse events. CONCLUSIONS: Softening of the stool was related to the eradication failure in the junior high school students, especially in males with abdominal pain. Adverse effects did not induce discontinuation of the eradication treatment.