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The pneumococcal capsule is indispensable for pathogenesis in systemic infections; however, many pneumococcal diseases, including conjunctivitis, otitis media, and some systemic infections in immunocompromised patients, are caused by nonencapsulated Streptococcus pneumoniae (NESp). Null capsule clade 1 (NCC1), found in group 2 NESp, expresses pneumococcal surface protein K (PspK) and is becoming prevalent among pneumococcal organisms owing to the widespread use of pneumococcal conjugate vaccines. Despite its clinical importance, the molecular mechanisms underlying the prevalence of NCC1 have not been fully elucidated. Here, we investigated the role of the R3 domain of PspK in the epithelial cell adherence of NCC1. We found that the R3 domain of PspK mediated NCC1 adherence via its direct interaction with the epithelial surface protein annexin A2. Additionally, neutralization with purified recombinant PspK-R3 or rabbit anti-UD:R3 IgG inhibited binding of NESp to lung epithelial cells in vitro. Immunization with the 'repeat' domain of PspK-R3 or PspK-UD:R3 effectively elicited mucosal and systemic immune responses against PspK-R3 and provided protection against nasopharyngeal, lung, and middle ear colonization of NESp in mice. Additionally, we found that rabbit anti-UD:R3 IgG bound to PspC-R1 of the encapsulated TIGR4 strain and that UD:R3 immunization provided protection against nasopharyngeal and lung colonization of TIGR4 and deaths by TIGR4 and D39 in mice. Further studies using 68 pneumococcal clinical isolates showed that 79% of clinical isolates showed cross-reactivity to rabbit anti-UD:R3 IgG. About 87% of serotypes in the 13-valent pneumococcal conjugate vaccine (PCV) and 68% of non-vaccine serotypes were positive for cross-reactivity with rabbit anti-UD:R3 IgG. Thus, the R3 domain of PspK may be an effective vaccine candidate for both NESp and encapsulated Sp.

Foot-and-mouth disease virus (FMDV) is highly infectious and causes a major plague in animal farming. Unfolded protein response is one of the major cellular responses to pathogenic infections, which performs a crucial role in cell survival, apoptosis, and antiviral innate immune response. In this study, we showed that FMDV infection activated two unfolded protein response branches (PERK-eIF2α and ATF6 signaling) in both baby hamster kidney cells (BHK-21) and porcine kidney (PK-15) cells, whereas it suppressed the IRE1α-XBP1 signaling by decreasing IRE1α level. Further study revealed IRE1α signaling as an important antiviral innate immune mechanism against FMDV. Sec62, the transport protein, was greatly decreased at the late stages of FMDV infection. By overexpression and knockdown study, we also found that the expression of Sec62 was positively involved in the levels of IRE1α and RIG-I and subsequent activation of downstream antiviral signaling pathways in FMDV-infected PK-15 cells. Taken together, our study demonstrates that Sec62 is an important antiviral factor that upregulates IRE1α–RIG-I–dependent antiviral innate immune responses, and FMDV evades antiviral host defense mechanism by downregulating Sec62-IRE1α/RIG-I.

Methicillin‑resistant Staphylococcus aureus (MRSA) is difficult to treat using available antibiotic agents. Honeybee venom has been widely used as an oriental treatment for several inflammatory diseases and bacterial infections. The venom contains predominantly biologically active compounds, however, the therapeutic effects of such materials when used to treat MRSA infections have not been investigated extensively. The present study evaluated bee venom and its principal active component, melittin, in terms of their antibacterial activities and in vivo protection against MRSA infections. In vitro, bee venom and melittin exhibited comparable levels of antibacterial activity, which was more marked against MRSA strains, compared with other Gram‑positive bacteria. When MRSA‑infected mice were treated with bee venom or melittin, only the latter animals were successfully rescued from MRSA‑ induced bacteraemia or exhibited recovery from MRSA‑infected skin wounds. Together, the data of the present study demonstrated for the first time, to the best of our knowledge, that melittin may be used as a promising antimicrobial agent to enhance the healing of MRSA‑induced wounds.

This study was undertaken to investigate the effect of a magnetic resonance imaging (MRI) contrast agent, superparamagnetic iron oxide nanoparticle (SPIO), on signal transduction by glucose and insulin in pancreatic β-cells. INS-1 cells were labeled in culture medium containing clinically approved SPIO for 24 h. Labeled and unlabeled cells were stimulated with glucose (25 mM) or insulin (0.1-1 µM) for 12 h. The phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) and protein kinase B (AKT) and intracellular insulin protein levels were assessed by Western blotting. After labeling with increasing amounts of SPIO, cytotoxicity was not observed, yet the intracellular iron concentration increased in a dose-dependent manner. SPIO labeling (200 µg Fe ml(-1)) induced a significant increase in ERK1/2 and AKT phosphorylation (labeled vs unlabeled, p < 0.05), but significantly reduced the glucose-stimulated phosphorylation of ERK1/2 and AKT and insulin-stimulated phosphorylation of AKT (labeled vs unlabeled, p < 0.05). The level of intracellular insulin protein was found to be lower in labeled cells than unlabeled cells (labeled vs unlabeled, p < 0.05). This study demonstrates that SPIO labeling alters some fundamental functional variables, at least in INS-1 cells, through modulation of the glucose- or insulin-induced activation of ERK1/2 and AKT, which leads to insulin biosynthesis.

Background Development of group B streptococcus (GBS) vaccine is currently underway. In order to establish the immunization policy for the future, it is necessary to understand the basal immune level of risk groups in each country. Methods Thirty serum samples were collected from each risk group (neonates/infants, pregnant women and the elderly) between August 2016 and July 2017 at Korea University Guro hospital. Serotype-specific opsonic index (OI) was assessed using GBS multiplex opsonophagocytic killing assay (MOPA) against serotype Ia, III and V, which are most prevalent worldwide. Results The mean age of neonates/infants, pregnant women, and the elderly was 1.3 months (range, 1–3 months), 31.9 years (range, 23–41 years) and 68.8 years (range 65–76 years), respectively. Baseline OI of each risk group measured by MOPA was shown in Table 1. The mean OI of serotype Ia was not significantly different among three risk groups (P = 0.156), but relatively lower in the neonates/infants group (mean ± standard deviation, 137 ± 278). For serotype III, the mean OI of neonates/infants (338 ± 623) was significantly lower compared with those of pregnant women (1,377 ± 1167) and old adults (1,350 ± 1741)(P = 0.002); Overall 60% of neonates/infants showed OI below 100. As for the serotype V, OI was particularly lower in neonates/infants (161 ± 445) compared with the elderly (3,669 ± 5,597) and pregnant women (9,414 ± 6,394) with statistically significant differences between three risk groups (P < 0.001). Conclusion Considering the relatively low OI of neonates/infants despite high maternal titer, intrapartum GBS vaccination might be required to ensure efficient placental transfer of serotype-specific GBS antibodies with high avidity. Table 1. Comparison of Baseline Opsonic Indexes Between Risk Groups: Mean Opsonic Indexes and 95% Confidence Intervals Serotypes Groups Opsonic Index (Mean) 95% CI P-Value Ia Neonates/infants 137 33–241 0.596 Pregnant women 285 17–552 The Elderly 231 3–459 III Neonates/infants 338 105–570 0.002 Pregnant women 1377 941–1813 The elderly 1350 700 - 2000 V Neonates/infants 161 -5–327

This study was undertaken to investigate the effect of a magnetic resonance imaging (MRI) contrast agent, superparamagnetic iron oxide nanoparticle (SPIO), on signal transduction by glucose and insulin in pancreatic β-cells. INS-1 cells were labeled in culture medium containing clinically approved SPIO for 24 h. Labeled and unlabeled cells were stimulated with glucose (25 mM) or insulin (0.1-1 µM) for 12 h. The phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) and protein kinase B (AKT) and intracellular insulin protein levels were assessed by Western blotting. After labeling with increasing amounts of SPIO, cytotoxicity was not observed, yet the intracellular iron concentration increased in a dose-dependent manner. SPIO labeling (200 µg Fe ml(-1)) induced a significant increase in ERK1/2 and AKT phosphorylation (labeled vs unlabeled, p0.05), but significantly reduced the glucose-stimulated phosphorylation of ERK1/2 and AKT and insulin-stimulated phosphorylation of AKT (labeled vs unlabeled, p0.05). The level of intracellular insulin protein was found to be lower in labeled cells than unlabeled cells (labeled vs unlabeled, p0.05). This study demonstrates that SPIO labeling alters some fundamental functional variables, at least in INS-1 cells, through modulation of the glucose- or insulin-induced activation of ERK1/2 and AKT, which leads to insulin biosynthesis.

For ultrasensitive magnetic resonance imaging (MRI), magnetic nanoparticles with extremely high r2 relaxivity are strongly desired. Magnetosome-like nanoparticles were prepared by coating polyethylene glycol-phospholipid (PEG-phospholipid) onto ferrimagnetic iron oxide nanocubes (FIONs). FIONs exhibited a very high relaxivity (r2) of 324 mM -1 s -1 , allowing efficient labeling of various kinds of cells. The magnetic resonance (MR) imaging of single cells labeled with FIONs is demonstrated not only in vitro but also in vivo. Pancreatic islet grafts and their rejection could be imaged using FIONs on a 1.5 T clinical MRI scanner. The strong contrast effect of FIONs enabled MR imaging of transplanted islets in small rodents as well as in large animals. Therefore, we expect that MR imaging of pancreatic islet grafts using FIONs has the potentials for clinical applications. Furthermore, FIONs will enable highly sensitive noninvasive assessment after cell transplantation.

Objective: To determine the feasibility of labeling human mesenchymal stem cells (hMSCs) with bifunctional nanoparticles and assessing their potential as imaging probes in the monitoring of hMSC transplantation. Materials and Methods: The T1 and T2 relaxivities of the nanoparticles (MNP@SiO2[RITC]-PEG) were measured at 1.5T and 3T magnetic resonance scanner. Using hMSCs and the nanoparticles, labeling efficiency, toxicity, and proliferation were assessed. Confocal laser scanning microscopy and transmission electron microscopy were used to specify the intracellular localization of the endocytosed iron nanoparticles. We also observed in vitro and in vivo visualization of the labeled hMSCs with a 3T MR scanner and optical imaging. Results: MNP@SiO 2 (RITC)-PEG showed both superparamagnetic and fluorescent properties. The r 1 and r 2 relaxivity values of the MNP@SiO2(RITC)-PEG were 0.33 and 398 mM -1 s -1 at 1.5T, respectively, and 0.29 and 453 mM -1 s -1 at 3T, respectively. The effective internalization of MNP@SiO2(RITC)-PEG into hMSCs was observed by confocal laser scanning fluorescence microscopy. The transmission electron microscopy images showed that MNP@SiO2(RITC)-PEG was internalized into the cells and mainly resided in the cytoplasm. The viability and proliferation of MNP@SiO2(RITC)-PEG-labeled hMSCs were not significantly different from the control cells. MNP@SiO2(RITC)-PEG-labeled hMSCs were observed in vitro and in vivo with optical and MR imaging. Conclusion: MNP@SiO2(RITC)-PEG can be a useful contrast agent for stem cell imaging, which is suitable for a bimodal detection by MRI and optical imaging.