USV-Observed Turbulent Heat Flux Induced by Late Spring Cold Dry Air Incursion over Sub-Mesoscale Warm Regions off Sanriku, Japan.

We performed oceanic and atmospheric observations in the region off the Sanriku coast, Japan, from May 11 to 5 July 2022, using a wave-propelled unmanned surface vehicle, a Wave Glider (WG). Despite the severe weather conditions of atmospheric low-pressure system crossings, we successfully measured wind, air temperature, humidity, and sea surface temperature over the course of 55 days to calculate the turbulent heat flux. The WG observed that the atmosphere became more humid due to the southerly wind along the northwestern rim of the North Pacific subtropical high. The warm Kuroshio water expanded to the southeast of Hokkaido as a result of the northward shedding of an anticyclonic mesoscale (~100 km) eddy, called a warm-core ring, from the Kuroshio Extension. The WG traversed smaller (sub-mesoscale) water regions that were warmer and saltier than the surrounding Kuroshio water. The observations indicate that cold, dry air masses advected by northerly winds following the passage of atmospheric low-pressure systems generate a substantial upward turbulent heat flux over sub-mesoscale warm water regions, contrasting to no heat flux in the surrounding Kuroshio water region.

Involvement of herpes simplex virus type 1 UL13 protein kinase in induction of SOCS genes, the negative regulators of cytokine signaling.

The suppressor of cytokine signaling (SOCS) family has eight members and suppresses various cytokine signaling pathways, including IFN signaling. Therefore, some viruses have evolved molecular mechanisms for inducing SOCS proteins and thus escaping host immunity. Herpes simplex virus type 1 (HSV-1) has a mechanism for escaping from type I IFN by induction of both SOCS1 and SOCS3. In this study, expression of the eight members of the SOCS family stimulated by HSV-1 infection was comparatively analyzed by qRT-PCR. It was found that SOCS1 and SOCS3 are induced by HSV-1-infection at 4 hr post infection. However, such induction was not observed in UL13 deficient virus-infected cells, suggesting that UL13 protein kinase participates in induction of both genes. The transcription factor Sp1-binding sites of SOCS3 promoter/enhancer region were identified as the regulatory elements for induction of SOCS3 in HSV-1 infected cells. Accumulation of activated Sp1 was detectable in the nuclei of HSV-1-infected cells before induction of SOCS3. Taken together, these results suggest that HSV-1 has a potent mechanism for escaping from the IFN system.

Imiquimod suppresses propagation of herpes simplex virus 1 by upregulation of cystatin A via the adenosine receptor A1 pathway.

Imiquimod is recognized as an agonist for Toll-like receptor 7 (TLR7) in immunocompetent cells. TLR7, as well as TLR3 and TLR8, triggers the immune responses, such as the production of type I interferons (IFNs) and proinflammatory cytokines via recognition of viral nucleic acids in the infected cells. In this study, we proposed that imiquimod has an IFN-independent antiviral effect in nonimmune cells. Imiquimod, but not resiquimod, suppressed replication of human herpes simplex virus 1 (HSV-1) in FL cells. We analyzed alternation of gene expression by treatment with imiquimod using microarray analysis. Neither type I IFNs, nor TLRs, nor IFN-inducible antiviral genes were induced in imiquimod-treated FL cells. Cystatin A, a host cysteine protease inhibitor, was strongly upregulated by imiquimod and took a major part in the anti-HSV-1 activity deduced by the suppression experiment using its small interfering RNA. Upregulation of cystatin A was suggested to be mediated by antagonizing adenosine receptor A(1) and activating the protein kinase A pathway. Imiquimod, but not resiquimod, was shown to interact with adenosine receptor A(1). Imiquimod-induced anti-HSV-1 activity was observed in other cells, such as HeLa, SiHa, and CaSki cells, in a manner consistent with the cystatin A induction by imiquimod. These results indicated that imiquimod acted as an antagonist for adenosine receptor A(1) and induced a host antiviral protein, cystatin A. The process occurred independently of TLR7 and type I IFNs.

Positive relationship between a polymorphism in Helicobacter pylori neutrophil-activating protein a gene and iron-deficiency anemia.

BACKGROUND: Numerous studies have suggested a link between iron-deficiency anemia (IDA) and Helicobacter pylori infection. Previously, we found that strains isolated from IDA patients showed higher levels of Fe ion uptake and Fe-ion-dependent rapid proliferation than those of strains derived from patients without IDA. MATERIALS AND METHODS: Twenty-four H. pylori strains from IDA patients (IDA strains) and 25 strains from patients who had H. pylori gastritis without anemia (non-IDA strains) were examined. Their nucleotide sequences of napA, fur, and feoB, which contribute to Fe ion uptake, were determined. RESULTS: Numerous polymorphisms of the three genes were found in both strains. Frequency of neutrophil-activating protein A (NapA), which encoded by napA, with threonine at amino acid residue No. 70 (Thr70-type NapA) was significantly higher in IDA strains than in non-IDA strains. Strains with Thr70-type NapA showed significantly higher levels of Fe(3+) and Fe(2+) uptake than did strains with other types, Ser70-type of NapA, which is found in standard strains. Other significantly different occurrences of polymorphisms between IDA and non-IDA groups were not observed in these genes. CONCLUSION: The results suggest that H. pylori strains with Thr70-type NapA have enhanced Fe ion uptake ability and are associated with the pathogenesis of IDA.

Pulmonary collectins play distinct roles in host defense against Mycobacterium avium.

Pulmonary collectins, surfactant protein A (SP-A) and surfactant protein D (SP-D), play important roles in the innate immunity of the lung. Mycobacterium avium is one of the well-known opportunistic pathogens that can replicate within macrophages. We examined the effects of pulmonary collectins in host defense against M. avium infection achieved via direct interaction between bacteria and collectins. Although both pulmonary collectins bound to M. avium in a Ca(2+)-dependent manner, these collectins revealed distinct ligand-binding specificity and biological activities. SP-A and SP-D bound to a methoxy group containing lipid and lipoarabinomannan, respectively. Binding of SP-D but not SP-A resulted in agglutination of M. avium. A chimeric protein with the carbohydrate recognition domain of SP-D, which chimera revealed a bouquet-like arrangement similar to SP-A, also agglutinated M. avium. The ligand specificity of the carbohydrate recognition domain of SP-D seems to be necessary for agglutination activity. The binding of SP-A strongly inhibited the growth of M. avium in culture media. Although pulmonary collectins did not increase membrane permeability of M. avium, they attenuated the metabolic rate of the bacteria. Observations under a scanning electron microscope revealed that SP-A almost completely covers bacterial surfaces, whereas SP-D binds to certain areas like scattered dots. These observations suggest that a distinct binding pattern of collectins correlates with the difference of their biological activities. Furthermore, the number of bacteria phagocytosed by macrophages was significantly increased in the presence of SP-D. These data indicate that pulmonary collectins play critical roles in host defense against M. avium.

High prevalence of cross-resistance to aminoglycosides in fluoroquinolone-resistant Escherichia coli clinical isolates.

BACKGROUND: Multidrug-resistant Escherichia coli, especially a lineage of O25b:H4-ST131, has increased and spread worldwide. The surveillance of cross-resistance of E. coli is necessary. METHODS: Cross-resistance to fluoroquinolones (FQs) and aminoglycosides (AGs) was examined in E. coli isolated in Hokkaido Prefecture, Japan, between 2008 and 2009. RESULTS: Gentamicin (GEN) resistance was more common in FQ-resistant isolates (30/112 strains; 26.8%) than in FQ-susceptible isolates (2/100 strains; 2%). The frequency of GEN resistance was similar in two groups of FQ-resistant strains, O25b:H4-ST131 genotype (22/87 strains; 25.3%) and a group of other FQ-resistant genotypes (8/25 strains; 32.0%). The main AG resistance gene was aac(3)-II (87.5% of GEN-resistant strains). The only amikacin-resistant strain which was FQ resistant carried the aac(6')-Ib-cr gene. CTX-M type extended-spectrum ß-lactamase (ESBL) genes were also found in FQ-resistant strains at a high frequency. However, the number of strains with both ESBL and AG-modifying enzyme genes was relatively low (8 strains). CONCLUSION: All FQ-resistant strains, not only O25b:H4-ST131, appeared to preferentially acquire ESBL genes and/or genes encoding AG-modifying enzymes; however, the acquisitions of these genes seemed to occur independently.

Humulone suppresses replication of respiratory syncytial virus and release of IL-8 and RANTES in normal human nasal epithelial cells.

Respiratory syncytial virus (RSV) is the major infectious agent causing serious respiratory tract inflammation in infants and young children. However, an effective vaccine and anti-viral therapy for RSV infection have not yet been developed. Hop-derived bitter acids have potent pharmacological effects on inflammation. Therefore, we investigated the effects of humulone, which is the main constituent of hop bitter acids, on the replication of RSV and release of the proinflammatory cytokine IL-8 and chemokine RANTES in RSV-infected human nasal epithelial cells (HNECs). We found that humulone prevented the expression of RSV/G-protein, formation of virus filaments and release of IL-8 and RANTES in a dose-dependent manner in RSV-infected HNECs. These findings suggest that humulone has protective effects against the replication of RSV, the virus assembly and the inflammatory responses in HNECs and that it is a useful biological product for the prevention and therapy for RSV infection.

Implication of antigenic conversion of Helicobacter pylori lipopolysaccharides that involve interaction with surfactant protein D.

We propose two antigenic types of Helicobacter pylori lipopolysaccharides (LPS): highly antigenic epitope-carrying LPS (HA-LPS) and weakly antigenic epitope-carrying LPS (WA-LPS) based on human serum reactivity. Strains carrying WA-LPS are highly prevalent in isolates from gastric cancer patients. WA-LPS exhibits more potent biological activities compared to HA-LPS, namely, upregulation of Toll-like receptor 4 (TLR4) expression and induction of enhanced epithelial cell proliferation. The results of competitive binding assays using monosaccharides and methylglycosides, as well as binding assays using glycosidase-treated LPS, suggested that ß-linked N-acetyl-D-glucosamine and ß-linked D-galactose residues largely contributed to the highly antigenic epitope and the weakly antigenic epitope, respectively. WA-LPS exhibited greater binding activity to surfactant protein D (SP-D) in a Ca(2+)-dependent manner, and this interaction was inhibited by methyl-ß-D-galactoside. The biological activities of WA-LPS were markedly enhanced by the addition of SP-D. Lines of evidence suggested that removal of ß-N-acetyl-D-glucosamine residue, which comprises the highly antigenic epitope, results in exposure of the weakly antigenic epitope. The weakly antigenic epitope interacted preferentially with SP-D, and SP-D enhanced the biological activity of WA-LPS.

Prevalence of fluoroquinolone-resistant Escherichia coli O25:H4-ST131 (CTX-M-15-nonproducing) strains isolated in Japan.

BACKGROUND: Fluoroquinolone-resistant and extended-spectrum ß-lactamase (ESBL)-carrying multidrug-resistant Escherichia coli have become severely problematic. In particular, a lineage of multilocus sequence-type ST131 which belongs to O25:H4 and carries ESBL CTX-M-15 has spread worldwide. METHODS: Fluoroquinolone-resistant E. coli strains were isolated from various clinical specimens in a commercial clinical laboratory in 2008 and 2009 in Hokkaido Prefecture, Japan. RESULTS: Among 478 clinical isolates, 112 strains (23.4%) showed levofloxacin (LVX) resistance. About 80% of the fluoroquinolone-resistant strains (88 strains) showed common features, namely O25:H4-ST131, phylogenetic group B and the same mutation pattern in quinolone resistance-determining regions. Pulsed field gel electrophoresis patterns suggested numerous lineages of O25:H4-ST131. The fluoroquinolone-resistant strains, including strains of O25:H4-ST131 and other types, more frequently shared CTX-type ESBL genes than did fluoroquinolone-susceptible strains. The ESBL genes fell into the CTX-M-9 and CTX-M-2 groups. CTX-M-15 (CTX-M-1 group) was not found among any of the strains isolated in this study. Sitafloxacin showed markedly potent activity against E. coli isolates compared with LVX, ciprofloxacin and ulifloxacin. CONCLUSION: The most prevalent fluoroquinolone-resistant strains of E. coli isolated in Hokkaido Prefecture, Japan, are O25:H4-ST131. However, similar to other areas of Japan, the ST131 clones represent distinct lineages from the general worldwide dispersal of multidrug-resistant clones which carry CTX-M-15.

Clarithromycin suppresses human respiratory syncytial virus infection-induced Streptococcus pneumoniae adhesion and cytokine production in a pulmonary epithelial cell line.

Human respiratory syncytial virus (RSV) sometimes causes acute and severe lower respiratory tract illness in infants and young children. RSV strongly upregulates proinflammatory cytokines and the platelet-activating factor (PAF) receptor, which is a receptor for Streptococcus pneumoniae, in the pulmonary epithelial cell line A549. Clarithromycin (CAM), which is an antimicrobial agent and is also known as an immunomodulator, significantly suppressed RSV-induced production of interleukin-6, interleukin-8, and regulated on activation, normal T-cell expressed and secreted (RANTES). CAM also suppressed RSV-induced PAF receptor expression and adhesion of fluorescein-labeled S. pneumoniae cells to A549 cells. The RSV-induced S. pneumoniae adhesion was thought to be mediated by the host cell's PAF receptor. CAM, which exhibits antimicrobial and immunomodulatory activities, was found in this study to suppress the RSV-induced adhesion of respiratory disease-causing bacteria, S. pneumoniae, to host cells. Thus, CAM might suppress immunological disorders and prevent secondary bacterial infections during RSV infection.

Pulmonary collectins protect macrophages against pore-forming activity of Legionella pneumophila and suppress its intracellular growth.

Pulmonary collectins, surfactant proteins A (SP-A) and D (SP-D), play important roles in innate immunity of the lung. Legionella pneumophila is a bacterial respiratory pathogen that can replicate within macrophages and causes opportunistic infections. L. pneumophila possesses cytolytic activity, resulting from insertion of pores in the macrophage membrane upon contact. We examined whether pulmonary collectins play protective roles against L. pneumophila infection. SP-A and SP-D bound to L. pneumophila and its lipopolysaccharide (LPS) and inhibited the bacterial growth in a Ca(2+)-dependent manner. The addition of LPS in the culture blocked the inhibitory effects on L. pneumophila growth by the collectins, indicating the importance of LPS-collectin interaction. When differentiated THP-1 cells were infected with L. pneumophila in the presence of SP-A and SP-D, the number of permeable cells was significantly decreased, indicating that pulmonary collectins inhibit pore-forming activity of L. pneumophila. The number of live bacteria within the macrophages on days 1-4 after infection was significantly decreased when infection was performed in the presence of pulmonary collectins. The phagocytosis experiments with the pH-sensitive dye-labeled bacteria revealed that pulmonary collectins promoted bacterial localization to an acidic compartment. In addition, SP-A and SP-D significantly increased the number of L. pneumophila co-localized with LAMP-1. These results indicate that pulmonary collectins protect macrophages against contact-dependent cytolytic activity of L. pneumophila and suppress intracellular growth of the phagocytosed bacteria. The promotion of lysosomal fusion with Legionella-containing phagosomes constitutes a likely mechanism of L. pneumophila growth suppression by the collectins.

Impact of anaerobic and oligotrophic conditions on survival of Alloiococcus otitidis, implicated as a cause of otitis media.

The survival of Alloiococcus otitidis (NCFB2890) with different nutritional supplements, including brain-heart infusion broth (BHI), phosphate-buffered saline (PBS), distilled water (DW), and middle ear effusion (MEE), as well as various atmospheres (aerobic, microaerobic, anaerobic), was compared using cultures, LIVE/DEAD staining, and transmission electron microscopy. The bacterial morphological traits and viability were maintained in BHI and MEE under aerobic conditions but were rapidly lost in PBS and DW. In contrast, anaerobic conditions did not support viability at all. Thus, the bacteria critically required an aerobic atmosphere for its survival as well as the appropriate nutrients, implying that culture of this pathogen from clinical specimens would become more difficult through oxygen depletion depending on a slight change in the middle ear atmosphere.

Helicobacter pylori lipopolysaccharides upregulate toll-like receptor 4 expression and proliferation of gastric epithelial cells via the MEK1/2-ERK1/2 mitogen-activated protein kinase pathway.

Helicobacter pylori is recognized as an etiological agent of gastroduodenal diseases. H. pylori produces various toxic substances, including lipopolysaccharide (LPS). However, H. pylori LPS exhibits extremely weakly endotoxic activity compared to the typical LPS, such as that produced by Escherichia coli, which acts through Toll-like receptor 4 (TLR4) to induce inflammatory molecules. The gastric epithelial cell lines MKN28 and MKN45 express TLR4 at very low levels, so they show very weak interleukin-8 (IL-8) production in response to E. coli LPS, but pretreatment with H. pylori LPS markedly enhanced IL-8 production induced by E. coli LPS by upregulating TLR4 via TLR2 and the MEK1/2-ERK1/2 pathway. The transcription factor NF-Y was activated by this signal and promoted transcription of the tlr4 gene. These MEK1/2-ERK1/2 signal-mediated activities were more potently activated by LPS carrying a weakly antigenic epitope, which is frequently found in gastric cancers, than by LPS carrying a highly antigenic epitope, which is associated with chronic gastritis. H. pylori LPS also augmented the proliferation rate of gastric epithelial cells via the MEK1/2-ERK1/2 pathway. H. pylori LPS may be a pathogenic factor causing gastric tumors by enhancing cell proliferation and inflammation via the MEK1/2-ERK1/2 mitogen-activated protein kinase cascade in gastric epithelial cells.

Acquisition of a transposon encoding extended-spectrum beta-lactamase SHV-12 by Pseudomonas aeruginosa isolates during the clinical course of a burn patient.

Three of seven clonally related Pseudomonas aeruginosa strains isolated from a burn patient produced the extended-spectrum beta-lactamase (ESBL) SHV-12. Its gene was flanked by two IS26 elements with a large transposon (>24 kb). The transposon also contained at least five IS26 elements and a gene encoding the amikacin resistance determinant aminoglycoside 6'-N-acetyltransferase type Ib [aac(6')-Ib]. It was inserted into the gene PA5317 in the P. aeruginosa chromosome.

The battle between virus and host: modulation of Toll-like receptor signaling pathways by virus infection.

In order to establish an infection, viruses need to either suppress or escape from host immune defense systems. Recent immunological research has focused on innate immunity as the first line of host defense, especially pattern recognition molecules such as Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), and NOD-like receptors (NLRs). Various microbial components are recognized by their vague and common molecular shapes so-called, pathogen-associated molecular patterns (PAMPs). PAMPs induce inflammatory reactions mediated by the activation of the transcription factor, NF-kappaB, and by interferons, which lead to an antiviral immune response. Viruses have the capacity to suppress or escape from this pattern recognition molecule-mediated antimicrobial response in various ways. In this paper, we review the various strategies used by viruses to modulate the pattern recognition molecule-mediated innate immune response.

Measles virus P protein suppresses Toll-like receptor signal through up-regulation of ubiquitin-modifying enzyme A20.

We recently reported that the activation of NF-kappaB and AP-1 was suppressed in monocytes infected with measles virus, but not in infected epithelial cells. This cell-type-specific suppression of the inflammatory response represents a potential for measles virus to evade host immune system. In the current study, we examined the suppression mechanism of lipopolysaccharide (LPS)-induced, namely Toll-like receptor 4 (TLR4)-mediated, activation of NF-kappaB and AP-1 in measles virus-infected monocytic cells. In the infected cells, LPS treatment failed to induce the formation of active protein kinase complex containing TAK1, TAB2 and tumor necrosis factor receptor-associated factor 6 (TRAF6), dissociate from TLR complexes containing Interleukin-1 receptor-associated kinase 1 (IRAK1). Ubiquitin-modifying enzyme A20, which is a host negative feedback regulator of NF-kappaB, was dramatically up-regulated in infected monocytic cells, but not in infected epithelial cells. Suppression of A20 expression by siRNA restored LPS-induced signaling in infected cells. Measles virus phosphoprotein (P protein) expression was necessary and sufficient for the induction of A20. P protein interacted indirectly with a negative regulatory motif in the A20 gene promoter, and released the suppression of A20 transcription, independent of the activation of NF-kappaB.

Enhanced Fe ion-uptake activity in Helicobacter pylori strains isolated from patients with iron-deficiency anemia.

Recent studies have suggested a link between iron-deficiency anemia and Helicobacter pylori infection. In the current study, strains of H. pylori derived from patients with iron-deficiency anemia showed enhanced Fe ion uptake and Fe ion-dependent rapid growth compared with those from patients with non-iron-deficiency anemia. H. pylori with enhanced Fe ion-uptake ability may be a causative factor for iron-deficiency anemia.

Emergence of fluoroquinolone-resistant Haemophilus influenzae strains among elderly patients but not among children.

We screened 457 Haemophilus influenzae strains isolated in Japan during 2002 to 2004 and identified 12 fluoroquinolone-resistant strains (2.6%). The resistant strains were divided into three genotypes (eight, three, and one of each type). These were isolated from patients over 58 years of age. Several fluoroquinolone-resistant clones appeared to have invaded the population of elderly patients in a particular area, Sapporo city.

Occurrence of norovirus infections unrelated to norovirus outbreaks in an asymptomatic food handler population.

Norovirus (NV) is the most common causative agent of nonbacterial gastroenteritis. Reports of surveillance of NV in facilities that reported outbreaks are frequently found in publications, but reports of that in facilities without outbreaks are not found. We investigated the molecular epidemiology of NV isolates derived from asymptomatic food handlers working at a non-outbreak food catering facility in Hokkaido, Japan, from February to March in 2005 and January to February in 2006 by RNA polymerase gene sequencing. Approximately 12% (20/159) of the samples were positive for genogroup II (GII; 10.1% in 2005 and 14.2% in 2006). The GI genotypes were not detected. The data from the phylogenetic analysis indicated that, among the 20 strains detected, 13 strains were GII/genotype 2 (GII/2), two were GII/3, three were GII/8, and two were GII/12. GII/4, which has been found most frequently in recent outbreaks worldwide, including Japan, was not detected. We found that one individual was coinfected with two genotypes, GII/2 and GII/12. This is the first report of the detection of NV genotypes in asymptomatic food handlers working at a non-outbreak facility. The excretion of NV from healthy individuals may be an infection source of NV outbreaks as well as other food-borne diseases.