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We report the isolation of Helicobacter ailurogastricus, a Helicobacter species that infects cats and dogs, from a person with multiple refractory gastric ulcers. In addition to H. suis, which infects pigs, Helicobacter species that infect cats and dogs should be considered as potential gastric pathogens in humans.

Helicobacter cinaedi infects the human gut and causes invasive infections such as bacteremia and cellulitis through bacterial translocation. However, the mechanism by which H. cinaedi attaches to host cells and establishes infection remains unclear. This study aimed to investigate the relationship between a novel putative autotransporter protein, H. cinaedi autotransporter protein A (HcaA), and its role in pathogenicity. The cytotoxicity of H. cinaedi infection in colon epithelial cell lines (Caco-2 and HT29) was assessed using a lactate dehydrogenase assay, and it was found that cytotoxicity significantly decreased upon HcaA knockout. Adhesion assays further revealed that the HcaA-knockout strain showed significantly reduced attachment to the human epithelial colorectal adenocarcinoma (Caco-2) cell line compared to that of the wild-type strain. Moreover, the recombinant HcaA protein demonstrated strong adhesion properties to the human monocytic cell line (U937). The adhesive activity was diminished when the Arg-Gly-Asp (RGD) motif in HcaA was replaced with RAD, indicating that the RGD motif in HcaA is crucial for host cell adhesion. To determine the role of HcaA in H. cinaedi infection in vivo , C57BL/6 mice were orally infected with wild-type and HcaA-knockout H. cinaedi strains. Bacterial colonization was assessed 7, 14, and 28 days post-infection. At 7 days post-infection, colonization was significantly lower in mice infected with the HcaA-knockout strain compared to those infected with the wild-type strain. In conclusion, our findings suggest that HcaA, a novel putative autotransporter protein in H. cinaedi , plays a significant role as an adhesin in establishing colonization. Helicobacter species are classified as gastric or enterohepatic according to their habitat. Among enterohepatic Helicobacter species, which inhabit the intestine, colon, and liver, Helicobacter cinaedi has been most frequently isolated from humans. H. cinaedi often causes bacteremia and cellulitis in immunocompromised hosts. Here, we focused on the H. cinaedi autotransporter protein A (HcaA), a novel virulence factor in H. cinaedi . We discovered that HcaA contributes to cell adhesion via its Arg-Gly-Asp motif. Furthermore, in animal experiments, bacterial colonization was reduced in mice infected with HcaA-knockout strains, supporting the hypothesis that HcaA contributes to H. cinaedi adhesion to host cells. Our study provides a novel mechanism for the establishment of H. cinaedi infections and provides new insights into the role of autotransporter proteins in the establishment of Helicobacter infection.

Helicobacter cinaedi infects the human gut and causes invasive infections such as bacteremia and cellulitis by bacterial translocation. However, how H. cinaedi attaches to host cells and establishes infection has not been elucidated. In this study, we focused on a novel autotransporter protein, i.e., H. cinaedi autotransporter protein A (HcaA) to examine its relationship with H. cinaedi pathogenicity. The cytotoxicity of H. cinaedi infection in the colon epithelial cell lines (Caco-2 and HT-29) by lactate dehydrogenase assay showed a significant reduction in cytotoxicity by HcaA knockout. Adhesion assays further revealed that the HcaA-knockout strain showed significantly reduced attachment of H. cinaedi to the human epithelial colorectal adenocarcinoma cell line (Caco-2) compared to the wild-type strain. To determine the role of HcaA in H. cinaedi infection in vivo, H. cinaedi wild-type and HcaA-knockout strains were orally infected C57BL/6 mice. The colonized bacteria were then measured 7, 14, and 28-days post-infection. The number of colonized H. cinaedi cells was significantly lower in HcaA-knockout strain infections than in wild-type strain infections at 7 days post-infection. Recombinant HcaA protein showed strong adhesion characteristics to the human monocytic cell line (U937) by adhesion assay used recombinant purified HcaA protein. The adherent activity was diminished by the replacement of the RGD motif in HcaA with RAD, indicating the contribution of the RGD motif in HcaA to host cell adherence. These results suggest that HcaA, a novel autotransporter protein in H. cinaedi, plays a significant role in establishing infection as an adhesin.

Anhydrobiosis, one of the most extensively studied forms of cryptobiosis, is induced in certain organisms as a response to desiccation. Anhydrobiotic species has been hypothesized to produce substances that can protect their biological components and/or cell membranes without water. In extremotolerant tardigrades, highly hydrophilic and heat-soluble protein families, cytosolic abundant heat-soluble (CAHS) proteins, have been identified, which are postulated to be integral parts of the tardigrades’ response to desiccation. In this study, to elucidate these protein functions, we performed in vitro and in vivo characterizations of the reversible self-assembling property of CAHS1 protein, a major isoform of CAHS proteins from Ramazzottius varieornatus , using a series of spectroscopic and microscopic techniques. We found that CAHS1 proteins homo-oligomerized via the C-terminal α-helical region and formed a hydrogel as their concentration increased. We also demonstrated that the overexpressed CAHS1 proteins formed condensates under desiccation-mimicking conditions. These data strongly suggested that, upon drying, the CAHS1 proteins form oligomers and eventually underwent sol–gel transition in tardigrade cytosols. Thus, it is proposed that the CAHS1 proteins form the cytosolic fibrous condensates, which presumably have variable mechanisms for the desiccation tolerance of tardigrades. These findings provide insights into molecular strategies of organisms to adapt to extreme environments.

Despite the fact that gut microbiota is closely associated with obesity, few studies have focused on the influences of paraprobiotics as food ingredients on both obesity prevention and the gut microbial community. In this study, we evaluated the effects of fragmented Lactobacillus amylovorus CP1563 (CP1563) as a paraprobiotic for obesity prevention and investigated its effects on the gut microbial community in pre-obese subjects. One hundred sixty-nine healthy subjects with a body mass index from 25.0 to 29.9 kg/m2 ingested beverages with or without the fragmented CP1563 containing 10-hydroxyoctadecanoic acid (10-HOA) for 12 weeks. The changes in abdominal, total, visceral, and subcutaneous fatty areas were significantly lower in the CP1563-10-HOA group than in the placebo group at 12 weeks. Furthermore, 16S rRNA gene sequencing of fecal DNA revealed that the changes in the abundances of the genera Roseburia and Lachnospiraceae;g were significantly greater in the CP1563-10-HOA group than in the placebo group, and the changes in the abundances of the genus Collinsella was significantly smaller in the CP1563-10HOA group than in the placebo group. Our results showed that continuous ingestion of the fragmented CP1563 containing 10-HOA reduced abdominal body fat and affected the gut microbial community in pre-obese healthy subjects. Our findings may contribute to the understanding of the relationship between the anti-obesity effect of paraprobiotics and gut microbiota.

Giant cell myocarditis (GCM) is a rare but fatal disease that can lead to cardiac failure. Survival with a cardiac standstill requires mechanical circulatory support or a biventricular assist device (BiVAD) and prolonged survival is extremely rare. Drug‐induced hypersensitivity syndrome (DIHS) is a severe cutaneous adverse reaction. Some cases of DIHS are reportedly associated with the onset of GCM. We present a case of a 28‐year‐old woman who developed GCM during steroid tapering after DIHS. She went into continuous cardiac standstill but survived for 74 days under BiVAD support. Our case is noteworthy because the histopathologic specimens obtained on three occasions contributed to the diagnosis of this particular condition over time. We also reviewed previous literature on concomitant cases of GCM and DIHS. We found that two are potentially associated and most cases of GCM occur within 3 months of DIHS during steroid tapering.

Histiocytic sarcoma in advanced clinical stages is typically an aggressive neoplasm, with poor response to conventional chemotherapy. An 18-year-old male with refractory histiocytic sarcoma that had transformed from Rosai–Dorfman disease was admitted to our hospital. A pathogenic variant of MAP2K1 was detected by next-generation sequencing of tumor specimens. Affected regions showed excellent responses to the MEK inhibitor trametinib. It has been reported that RAS/MEK/ERK pathway is activated in many cases of histiocytic sarcoma. MEK inhibition may represent a useful treatment option in histiocytic sarcoma.

Water is essential for life, but anhydrobiotic tardigrades can survive almost complete dehydration. Anhydrobiosis has been a biological enigma for more than a century with respect to how organisms sustain life without water, but the few choices of genetic toolkits available in tardigrade research have been a challenging circumstance. Here, we report the development of an in vivo expression system for tardigrades (the TardiVec system). TardiVec is based on a plasmid vector with promoters that originated from an anhydrobiotic tardigrade Ramazzottius varieornatus. It enables the introduction of GFP-fused proteins and genetically encoded indicators such as the Ca2+ indicator GCaMP into tardigrade cells; consequently, the dynamics of proteins and cells in tardigrades may be observed by fluorescence live imaging. This system is applicable for several tardigrades in the class Eutardigrada: the promoters of anhydrobiosis-related genes showed tissue-specific expression in this work. Surprisingly, promoters functioned similarly between multiple species, even for species with different modes of expression of anhydrobiosis-related genes, such as Hypsibius exemplaris, in which these genes are highly induced upon facing desiccation, and Thulinius ruffoi, which lacks anhydrobiotic capability. These results suggest that the highly dynamic expression changes in desiccation-induced species are regulated in trans. Tissue-specific expression of tardigrade-unique unstructured proteins also suggests differing anhydrobiosis machinery depending on the cell types. We believe that TardiVec opens up various experimental possibilities in tardigrade research, especially to explore anhydrobiosis mechanisms.