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Background Metagenomic analysis targeting the 16S rRNA gene has made it possible to characterize the vast array of microorganisms contained in the gut. Aim The purpose of this study was to evaluate how gut microbiota change in intensive care unit (ICU) patients in the acute phase after admission. Methods This prospective observational cohort study investigated 12 patients admitted to a single ICU of a large urban tertiary referral hospital. All patients were mechanically ventilated on admission. Fecal samples were collected from patients on days 1–2, 2–4, 5–8, and 7–10 after admission. DNA was extracted from fecal samples, and 16S rRNA deep sequencing was performed to monitor gut changes. Results Bacteria belonging to the phyla Firmicutes or Bacteroidetes were predominant in each sample. We observed serial dynamic changes in the percentages of Bacteroidetes and Firmicutes that were significantly altered during study period ( p  < 0.05). A ratio of Bacteroidetes to Firmicutes (B/F ratio) of >10 was seen in four of the six patients who died, whereas a B/F ratio of <0.10 was seen in only one of the six deaths. None of the survivors had a B/F ratio of >10 or <0.10. There was a statistical difference in the B/F ratio between the dead patients and survivors ( p  = 0.022). Conclusions Dynamic changes in gut microbiota at the phylum level of ICU patients during the acute phase were identified by high-throughput DNA sequencing. An extreme imbalance in gut microbiota may be associated with prognosis in critically ill patients.

Lypd8 protein derived from intestinal epithelial cells binds to flagellated bacteria to reduce their motility, which limits the entry of Gram-negative bacteria into the inner colonic mucus and prevents invasion of colonic epithelia. Lypd8 separates microbiota from epithelia This paper shows that the intestinal epithelial cell derived protein Lypd8, a member of member of the Ly6/PLAUR superfamily, binds to flagellated bacteria. In doing so it reduces the bacteria's motility, limits the entry of Gram-negative bacteria into the inner colonic mucus, and prevents invasion into colonic epithelium. Colonic epithelial cells are covered by thick inner and outer mucus layers 1 , 2 . The inner mucus layer is free of commensal microbiota, which contributes to the maintenance of gut homeostasis 3 , 4 , 5 , 6 . In the small intestine, molecules critical for prevention of bacterial invasion into epithelia such as Paneth-cell-derived anti-microbial peptides and regenerating islet-derived 3 (RegIII) family proteins have been identified 7 , 8 , 9 , 10 , 11 . Although there are mucus layers providing physical barriers against the large number of microbiota present in the large intestine, the mechanisms that separate bacteria and colonic epithelia are not fully elucidated. Here we show that Ly6/PLAUR domain containing 8 (Lypd8) protein prevents flagellated microbiota invading the colonic epithelia in mice. Lypd8, selectively expressed in epithelial cells at the uppermost layer of the large intestinal gland, was secreted into the lumen and bound flagellated bacteria including Proteus mirabilis . In the absence of Lypd8, bacteria were present in the inner mucus layer and many flagellated bacteria invaded epithelia. Lypd8 −/− mice were highly sensitive to intestinal inflammation induced by dextran sulfate sodium (DSS). Antibiotic elimination of Gram-negative flagellated bacteria restored the bacterial-free state of the inner mucus layer and ameliorated DSS-induced intestinal inflammation in Lypd8 −/− mice. Lypd8 bound to flagella and suppressed motility of flagellated bacteria. Thus, Lypd8 mediates segregation of intestinal bacteria and epithelial cells in the colon to preserve intestinal homeostasis.

Diabetes mellitus (DM) management has advanced from self-monitoring blood glucose (SMBG) to continuous glucose monitoring (CGM), which better prevents complications. However, the influence of periodontitis—a common DM complication—on glucose variability is unclear. This study examined glucose variability in mice with periodontitis using CGM. Periodontitis was induced in 9-week-old male C57BL/6J mice via silk ligatures around the upper second molars. Glucose levels were monitored over 14 days with CGM, validated by SMBG. On day 14, samples were collected to assess alveolar bone resorption and serum levels of tumor necrosis factor-α (TNF-α), insulin, and amyloid A. Glucose tolerance test (GTT) and insulin tolerance test (ITT) were conducted to evaluate insulin resistance. Gut microbiota diversity was also analyzed. By day 10, mice with periodontitis exhibited higher mean glucose levels and time above range than controls. On day 14, serum insulin and amyloid A levels significantly increased, while TNF-α remained unchanged. GTT and ITT indicated insulin resistance. Microbiota analysis showed reduced alpha- and altered beta-diversity, with decreased Coprococcus spp . and increased Prevotella spp. , linking dysbiosis to insulin resistance. Periodontitis disrupts glucose regulation by promoting insulin resistance and gut microbiota imbalance, leading to significant glucose variability.

Background/Objectives: Among various carbapenemases, New Delhi metallo-beta-lactamases (NDMs) are recognized as the most powerful type capable of hydrolyzing all beta-lactam antibiotics, often conferring multi-drug resistance to the microorganism. The objective of this review is to synthesize current scientific data on NDM inhibitors to facilitate the development of future therapeutics for challenging-to-treat pathogens. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews, we conducted a MEDLINE search for articles with relevant keywords from the beginning of 2009 to December 2022. We employed various generic terms to encompass all the literature ever published on potential NDM inhibitors. Results: Out of the 1760 articles identified through the database search, 91 met the eligibility criteria and were included in our analysis. The fractional inhibitory concentration index was assessed using the checkerboard assay for 47 compounds in 37 articles, which included 8 compounds already approved by the Food and Drug Administration (FDA) of the United States. Time-killing curve assays (14 studies, 25%), kinetic assays (15 studies, 40.5%), molecular investigations (25 studies, 67.6%), in vivo studies (14 studies, 37.8%), and toxicity assays (13 studies, 35.1%) were also conducted to strengthen the laboratory-level evidence of the potential inhibitors. None of them appeared to have been applied to human infections. Conclusions: Ongoing research efforts have identified several potential NDM inhibitors; however, there are currently no clinically applicable drugs. To address this, we must foster interdisciplinary and multifaceted collaborations by broadening our own horizons.

Gut-associated lymphoid tissues are responsible for the generation of IgA-secreting cells. However, the function of the caecal patch, a lymphoid tissue in the appendix, remains unknown. Here we analyse the role of the caecal patch using germ-free mice colonized with intestinal bacteria after appendectomy. Appendectomized mice show delayed accumulation of IgA + cells in the large intestine, but not the small intestine, after colonization. Decreased colonic IgA + cells correlate with altered faecal microbiota composition. Experiments using photoconvertible Kaede-expressing mice or adoptive transfer show that the caecal patch IgA + cells migrate to the large and small intestines, whereas Peyer’s patch cells are preferentially recruited to the small intestine. IgA + cells in the caecal patch express higher levels of CCR10. Dendritic cells in the caecal patch, but not Peyer’s patches, induce CCR10 on cocultured B cells. Thus, the caecal patch is a major site for generation of IgA-secreting cells that migrate to the large intestine. Gut-associated Peyer’s patches are lymphoid tissues that generate IgA-secreting cells, however less is known about related caecal patches. Here, Masahata et al. show that caecal patches produce IgA-positive B cells that migrate to the intestines to maintain faecal microbiota homeostasis.

Helicobacter pylori is a Gram-negative bacterium that inhabits the gastric mucosa, with a global prevalence in humans of approximately 40%. It is likely the cause of 90% of gastric cancer (GC) cases and thus considered the most prominent driver of GC development. However, during gastric mucosal atrophy, other bacteria such as nitrate-reducing bacteria (NRB) also proliferate. In this study, we isolated NRB from patients with gastritis and GC to examine their effects on the epithelial cell cycle and production of various cytokines in monocytic cell lines. Bacterial counts (excluding H. pylori and NRB) increased with the progression of gastric mucosal atrophy and were significantly higher in patients with GC. Gastric epithelial cell lines were stimulated with isolated NRB, and the proportion of cells in each cell cycle was measured. Strains from patients with open-type gastritis progressed more rapidly through cell cycles than those from patients with GC. NRB isolated from gastric cancer had high nitrate-reducing activity. Thus, NRB may contribute to GC progression during H. pylori-induced carcinogenesis. Therefore, evaluating gastric atrophy and microbiota may be important for managing the risk of GC.

Background Boron neutron capture therapy (BNCT) is a molecularly targeted chemoradiation modality that relies on boron delivery agents such as p-borophenylalanine (BPA), which require LAT1 (L-type amino acid transporter 1) for tumor uptake. However, the limited efficacy of BPA in LAT1-low tumors restricts its therapeutic scope. To address this limitation, we developed a tumor marker–guided BNCT strategy targeting cancers overexpressing the clinically validated glycan biomarker CA19-9. Methods We conducted transcriptomic analyses using The Cancer Genome Atlas (TCGA) datasets to identify LAT1-low cancers with high CA19-9 expression. These analyses revealed elevated expression of fucosyltransferase 3 (FUT3), which underlies CA19-9 biosynthesis, in pancreatic, biliary, and ovarian malignancies. Based on this, we synthesized a novel boron compound, fucose-BSH, designed to selectively accumulate in CA19-9–positive tumors. We evaluated its physicochemical properties, pharmacokinetics, biodistribution, and antitumor efficacy in cell lines and xenograft models, comparing its performance to that of BPA. Results Fucose-BSH demonstrated significantly greater boron uptake in CA19-9–positive cell lines (AsPC-1, Panc 04.03, HuCCT-1, HSKTC, OVISE) compared to CA19-9–negative PANC-1. In HuCCT-1 xenografts, boron accumulation reached 36.2 ppm with a tumor/normal tissue ratio of 2.1, outperforming BPA. Upon neutron irradiation, fucose-BSH–mediated BNCT achieved > 80% tumor growth inhibition. Notably, fucose-BSH retained therapeutic efficacy in LAT1-deficient models where BPA was ineffective, confirming LAT1-independent targeting. Conclusions This study establishes a novel precision BNCT approach by leveraging CA19-9 as a tumor-selective glycan marker for boron delivery. Fucose-BSH offers a promising platform for expanding BNCT to previously inaccessible LAT1-low malignancies, including pancreatic, biliary, and ovarian cancers. These findings provide a clinically actionable strategy for tumor marker–driven chemoradiation and lay the foundation for translational application in BNCT. This strategy has the potential to support companion diagnostic development and precision stratification in ongoing and future BNCT clinical trials. Translational Relevance Malignancies with elevated CA19-9 expression, such as pancreatic, biliary, and ovarian cancers, are associated with poor prognosis and limited response to current therapies. This study presents a tumor marker–guided strategy for boron neutron capture therapy (BNCT) by leveraging CA19-9 glycan biology to enable selective tumor targeting via fucose-BSH, a novel boron compound. Through transcriptomic data mining and preclinical validation, fucose-BSH demonstrated LAT1-independent boron delivery, potent BNCT-mediated cytotoxicity, and tumor-specific accumulation in CA19-9–positive models. These findings support a precision chemoradiation approach that addresses a critical gap in BNCT applicability, offering a clinically actionable pathway for patient stratification and therapeutic development in CA19-9–expressing cancers. Graphical Abstract

Many Gram-negative pathogens utilize dedicated secretion systems to export virulence factors such as exotoxins and effectors 1 – 4 . Several exotoxins are synthesized as precursors containing amino-terminal Sec signal peptides and are exported through the inner-membrane-bound Sec machinery to the periplasm, followed by secretion across the outer membrane to the exterior using a type II secretion system (T2SS) 3 , 5 . Here, we report that thermostable direct haemolysin (TDH), an exotoxin of the food-borne pathogen Vibrio parahaemolyticus , can be exported through the type III secretion system (T3SS), which engages in one-step secretion of effectors 4 , despite possessing a Sec signal peptide and being mainly secreted via the T2SS. Although the precursor of TDH is targeted to the Sec pathway, a fraction of mature TDH was observed to re-enter the bacterial cytoplasm. The N terminus of mature TDH comprises a T3SS signal sequence, allowing it to be loaded into the T3SS. We also show that T3SS-delivered TDH as an effector contributes to intestinal fluid accumulation in a rabbit diarrhoeal model of V.   parahaemolyticus infection. Thus, our results show that an unconventional export mechanism for a bacterial toxin via the T3SS in tandem with the Sec machinery facilitates the virulence trait of V.   parahaemolyticus . The Vibrio parahaemolyticus toxin, thermostable direct haemolysin, utilizes secretion by both type II and type III secretion systems to induce virulence traits.

The emergence of high-level daptomycin (DAP)-resistant (HLDR) Corynebacterium striatum has been reported as a result of loss-of-function point mutations or premature stop codon mutations in a responsible gene, pgsA2. We herein describe the novel detection of an HLDR C. striatum clinical isolate, in which IS30-insertion was corroborated to cause destruction of pgsA2 gene. We isolated an HLDR C. striatum from a critically ill patient with underlying mycosis fungoides who had been treated with DAP for 10 days. With a sequence investigation, IS30-insertion was discovered to split pgsA2 in the HLDR C. striatum strain, which may cause disrupted phospholipid phosphatidylglycerol (PG) production. Future studies should survey the prevalence of IS-mediated gene inactivation among HLDR C. striatum clinical isolates.