BMP10 functions independently from BMP9 for the development of a proper arteriovenous network.

Hereditary hemorrhagic telangiectasia (HHT) is a genetic vascular disorder characterized by the presence of arteriovenous malformation (AVM) in multiple organs. HHT is caused by mutations in genes encoding major constituents for transforming growth factor-ß (TGF-ß) family signaling: endoglin (ENG), activin receptor-like kinase 1 (ALK1), and SMAD4. The identity of physiological ligands for this ENG-ALK1 signaling pertinent to AVM formation has yet to be clearly determined. To investigate whether bone morphogenetic protein 9 (BMP9), BMP10, or both are physiological ligands of ENG-ALK1 signaling involved in arteriovenous network formation, we generated a novel Bmp10 conditional knockout mouse strain. We examined whether global Bmp10-inducible knockout (iKO) mice develop AVMs at neonatal and adult stages in comparison with control, Bmp9-KO, and Bmp9/10-double KO (dKO) mice. Bmp10-iKO and Bmp9/10-dKO mice showed AVMs in developing retina, postnatal brain, and adult wounded skin, while Bmp9-KO did not display any noticeable vascular defects. Bmp10 deficiency resulted in increased proliferation and size of endothelial cells in AVM vessels. The impaired neurovascular integrity in the brain and retina of Bmp10-iKO and Bmp9/10-dKO mice was detected. Bmp9/10-dKO mice exhibited the lethality and vascular malformation similar to Bmp10-iKO mice, but their phenotypes were more pronounced. Administration of BMP10 protein, but not BMP9 protein, prevented retinal AVM in Bmp9/10-dKO and endothelial-specific Eng-iKO mice. These data indicate that BMP10 is indispensable for the development of a proper arteriovenous network, whereas BMP9 has limited compensatory functions for the loss of BMP10. We suggest that BMP10 is the most relevant physiological ligand of the ENG-ALK1 signaling pathway pertinent to HHT pathogenesis.

Evolution of neutralizing antibodies through vaccination and breakthrough infections in the era of COVID-19 endemicity.

Despite a high vaccination rate, the COVID-19 pandemic continues with immune-evading Omicron variants. The success of additional antigenic stimulation through breakthrough infection (BI) and updated vaccination in overcoming antigenic imprinting needs to be determined. Participants in a long-term follow-up cohort of healthcare worker (HCW) vaccinee were categorized according to their infection/vaccination status. Anti-SARS-CoV-2 spike/nucleocapsid protein antibodies were measured, and plaque reduction neutralization tests (PRNTs) against wild-type (WT), BA.5, BN.1, and XBB.1.5 were conducted. The neutralization activity of intravenous immunoglobulin (IVIG) products was evaluated to assess the immune status of the general population. Ninety-five HCWs were evaluated and categorized into seven groups. The WT PRNT ND50 value was highest regardless of infection/vaccination status, and groups with recent antigenic stimulation showed high PRNT titers overall. Groups with double Omicron stimulation, either by BI plus BA.4/5 bivalent vaccination or repeated BI, exhibited significantly higher BA.5 and BN.1 PRNT to WT PRNT ratios than those with single Omicron stimulation. Overall group immunity was estimated to be boosted in January 2023, reflecting the effect of the BA.4/5 bivalent booster and additional BIs, but slightly declined in June 2023. A substantial increase in the antibody concentrations of IVIG products was noticed in 2022, and recently produced IVIG products exhibited a substantial level of cross-reactive neutralizing activity against emerging variants. Neutralizing activity against emerging variants could be enhanced by repeated antigenic stimulation via BI and/or updated vaccination. Overall group immunity was elevated accordingly, and IVIG products showed substantial activity against circulating strains.

Clinical utility of quantitative immunoassays and surrogate virus neutralization tests for predicting neutralizing activity against the SARS-CoV-2 Omicron BA.1 and BA.5 variants.

Developing new antibody assays for emerging SARS-CoV-2 variants is challenging. SARS-CoV-2 surrogate virus neutralization tests (sVNT) targeting Omicron BA.1 and BA.5 have been devised, but their performance needs to be validated in comparison with quantitative immunoassays. First, using 1749 PRNT-positive sera, we noticed that log-transformed optical density (OD) ratio of wild-type (WT) sVNT exhibited better titer-correlation with plaque reduction neutralization test (PRNT) than % inhibition value. Second, we tried 798 dilutional titration tests with 103 sera, but nonlinear correlation between OD ratio and antibody concentration limited titration of sVNT. Third, the titer-correlations of two sVNT kits for BA.1 and two quantitative immunoassays for WT were evaluated with BA.1 and BA.5 PRNT. All tested kits exhibited a linear correlation with PRNT titers, but the sVNT kits exhibited high false-negative rates (cPass-BA.1 kit, 45.4% for BA.1 and 44.2% for BA.5; STANDARD F-BA.1 kit, 1.9% for BA.1 and 2.2% for BA.5), while quantitative immunoassays showed 100% sensitivity. Linear mixed-effects model suggested superior titer-correlation with PRNT for quantitative immunoassays compared to sVNT kits. Taken together, the use of quantitative immunoassays for WT, rather than rapid development of new kits, would be practical for predicting neutralizing activities against emerging new variants.

A preliminary study about the potential risks of the UV-weathered microplastic: The proteome-level changes in the brain in response to polystyrene derived weathered microplastics.

The growing use of plastic materials has resulted in a constant increase in the risk associated with microplastics (MPs). Ultra-violet (UV) light and wind break down modify MPs in the environment into smaller particles known as weathered MPs (WMPs) and these processes increase the risk of MP toxicity. The neurotoxicity of weathered polystyrene-MPs remains unclear. Therefore, it is important to understand the risks posed by WMPs. We evaluated the chemical changes of WMPs generated under laboratory-synchronized environmentally mimetic conditions and compared them with virgin MPs (VMPs). We found that WMP had a rough surface, slight yellow color, reduced molecular weight, and structural alteration compared with those of VMP. Next, 2 µg of ∼100 µm in size of WMP and VMP were orally administered once a day for one week to C57BL/6 male mice. Proteomic analysis revealed that the WMP group had significantly increased activation of immune and neurodegeneration-related pathways compared with that of the VMP group. Consistently, in in vitro experiments, the human brain-derived microglial cell line (HMC-3) also exhibited a more severe inflammatory response to WMP than to VMP. These results show that WMP is a more profound inflammatory factor than VMP. In summary, our findings demonstrate the toxicity of WMPs and provide theoretical insights into their potential risks to biological systems and even humans in the ecosystem.

Bicistronic reporter mice for monitoring of Fgf21 expression.

Fibroblast growth factor 21 (FGF21) is a metabolic hormone that is synthesized and secreted by cellular and metabolic stresses. Serum FGF21 levels are associated with clinical parameters in patients with various diseases, including metabolic disorders. Animal models that allow FGF21 levels to be monitored in vivo are important for research and clinical applications of FGF21. Here, a novel Fgf21-reporter mouse strain (Fgf21+/Luc2-tdT) expressing luciferase and tandem dimer tomato (tdT) fluorescence proteins under the control of the endogenous Fgf21 promoter was generated, which provided an in vitro and in vivo monitoring tool for the Fgf21 expression. Luciferase activity, in vivo bioluminescence, and tdT fluorescence were analyzed in adult mice fed or fasted for 24 h. Luciferase activities were significantly increased in the liver but slightly decreased in the pancreas of fasted mice compared with those of fed mice. In vivo bioluminescence signal was increased in the liver of fasted mice. Obvious tdT fluorescence was detected in the pancreas. These results suggest that Fgf21-reporter mice have great potential for research and clinical applications of FGF21.

SARS-CoV-2 spike trimer vaccine expressed in Nicotiana benthamiana adjuvanted with Alum elicits protective immune responses in mice.

The ongoing coronavirus disease 2019 (COVID-19) pandemic has spurred rapid development of vaccines as part of the public health response. However, the general strategy used to construct recombinant trimeric severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) proteins in mammalian cells is not completely adaptive to molecular farming. Therefore, we generated several constructs of recombinant S proteins for high expression in Nicotiana benthamiana. Intramuscular injection of N. benthamiana-expressed Sct vaccine (NSct Vac) into Balb/c mice elicited both humoral and cellular immune responses, and booster doses increased neutralizing antibody titres. In human angiotensin-converting enzyme knock-in mice, two doses of NSct Vac induced anti-S and neutralizing antibodies, which cross-neutralized Alpha, Beta, Delta and Omicron variants. Survival rates after lethal challenge with SARS-CoV-2 were up to 80%, without significant body weight loss, and viral titres in lung tissue fell rapidly, with no infectious virus detectable at 7-day post-infection. Thus, plant-derived NSct Vac could be a candidate COVID-19 vaccine.

Overexpression of Activin Receptor-Like Kinase 1 in Endothelial Cells Suppresses Development of Arteriovenous Malformations in Mouse Models of Hereditary Hemorrhagic Telangiectasia.

RATIONALE: Hereditary hemorrhagic telangiectasia (HHT) is a genetic disease caused by mutations in ENG, ALK1, or SMAD4. Since proteins from all 3 HHT genes are components of signal transduction of TGF-ß (transforming growth factor ß) family members, it has been hypothesized that HHT is a disease caused by defects in the ENG-ALK1-SMAD4 linear signaling. However, in vivo evidence supporting this hypothesis is scarce. OBJECTIVE: We tested this hypothesis and investigated the therapeutic effects and potential risks of induced-ALK1 or -ENG overexpression (OE) for HHT. METHODS AND RESULTS: We generated a novel mouse allele (ROSA26Alk1) in which HA (human influenza hemagglutinin)-tagged ALK1 and bicistronic eGFP expression are induced by Cre activity. We examined whether ALK1-OE using the ROSA26Alk1 allele could suppress the development of arteriovenous malformations (AVMs) in wounded adult skin and developing retinas of Alk1- and Eng-inducible knockout (iKO) mice. We also used a similar approach to investigate whether ENG-OE could rescue AVMs. Biochemical and immunofluorescence analyses confirmed the Cre-dependent OE of the ALK1-HA transgene. We could not detect any pathological signs in ALK1-OE mice up to 3 months after induction. ALK1-OE prevented the development of retinal AVMs and wound-induced skin AVMs in Eng-iKO as well as Alk1-iKO mice. ALK1-OE normalized expression of SMAD and NOTCH target genes in ENG-deficient endothelial cells (ECs) and restored the effect of BMP9 (bone morphogenetic protein 9) on suppression of phosphor-AKT levels in these endothelial cells. On the other hand, ENG-OE could not inhibit the AVM development in Alk1-iKO models. CONCLUSIONS: These data support the notion that ENG and ALK1 form a linear signaling pathway for the formation of a proper arteriovenous network during angiogenesis. We suggest that ALK1 OE or activation can be an effective therapeutic strategy for HHT. Further research is required to study whether this therapy could be translated into treatment for humans.

Immunogenicity and Reactogenicity of Ad26.COV2.S in Korean Adults: A Prospective Cohort Study.

BACKGROUND: As the coronavirus disease 2019 (COVID-19) pandemic continues, there are concerns regarding waning immunity and the emergence of viral variants. The immunogenicity of Ad26.COV2.S against wild-type (WT) and variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) needs to be evaluated. METHOD: This prospective cohort study was conducted between June 2021 and January 2022 at two university hospitals in South Korea. Healthy adults who were scheduled to be vaccinated with Ad26.COV2.S were enrolled in this study. The main outcomes included anti-spike (S) IgG antibody and neutralizing antibody responses, S-specific T-cell responses (interferon-γ enzyme-linked immunospot assay), solicited adverse events (AEs), and serious AEs. RESULTS: Fifty participants aged ≥ 19 years were included in the study. Geometric mean titers (GMTs) of anti-S IgG were 0.4 U/mL at baseline, 5.2 ± 3.0 U/mL at 3-4 weeks, 55.7 ± 2.4 U/mL at 5-8 weeks, and 81.3 ± 2.5 U/mL at 10-12 weeks after vaccination. GMTs of 50% neutralizing dilution (ND50) against WT SARS-CoV-2 were 164.6 ± 4.6 at 3-4 weeks, 313.9 ± 3.6 at 5-8 weeks, and 124.4 ± 2.6 at 10-12 weeks after vaccination. As for the S-specific T-cell responses, the median number of spot-forming units/106 peripheral blood mononuclear cell was 25.0 (5.0-29.2) at baseline, 60.0 (23.3-178.3) at 5-8 weeks, and 35.0 (13.3-71.7) at 10-12 weeks after vaccination. Compared to WT SARS-CoV-2, ND50 against Delta and Omicron variants was attenuated by 3.6-fold and 8.2-fold, respectively. The most frequent AE was injection site pain (82%), followed by myalgia (80%), fatigue (70%), and fever (50%). Most AEs were grade 1-2, and resolved within two days. CONCLUSION: Single-dose Ad26.COV2.S was safe and immunogenic. NAb titer and S-specific T-cell immunity peak at 5-8 weeks and rather decrease at 10-12 weeks after vaccination. Cross-reactive neutralizing activity against the Omicron variant was negligible.

HDOP and VDOP Analysis in an Ideal Placement Environment for Dual GNSSs.

Increasing the number of satellites in a global navigation satellite system (GNSS) improves the positioning accuracy and increases availability. However, it reduces the positioning accuracy improvement rate and increases the calculation loads, which can cause battery usage problems in mobile devices using a GNSS. An appropriate satellite selection method is required. One current method entails the use of ideal satellite placement with respect to the minimum geometric dilution of precision (GDOP). In this study, the described ideal satellite placement with the minimum GDOP were divided in terms of the horizontal dilution of precision (HDOP) and vertical dilution of precision (VDOP). HDOP and VDOP were mathematically derived and analyzed. The derived formula was verified using simulations. The analysis was performed with actual dual GNSS satellite data. The satellites adjacent to the ideal placement were selected and the DOP was calculated. Simply selecting satellites closest to the ideal placement afforded large values for HDOP and VDOP. This issue was addressed using a satellite changing algorithm considering the dual GNSS, resulting in reduced values of the HDOP and VDOP.

Spatiotemporal expression of long noncoding RNA Moshe modulates heart cell lineage commitment.

The roles of long non-coding RNA (LncRNA) have been highlighted in various development processes including congenital heart defects (CHD). Here, we characterized the molecular function of LncRNA, Moshe (1010001N08ik-203), one of the Gata6 antisense transcripts located upstream of Gata6, which is involved in both heart development and the most common type of congenital heart defect, atrial septal defect (ASD). During mouse embryonic development, Moshe was first detected during the cardiac mesoderm stage (E8.5 to E9.5) where Gata6 is expressed and continues to increase at the atrioventricular septum (E12.5), which is involved in ASD. Functionally, the knock-down of Moshe during cardiogenesis caused significant repression of Nkx2.5 in cardiac progenitor stages and resulted in the increase in major SHF lineage genes, such as cardiac transcriptional factors (Isl1, Hand2, Tbx2), endothelial-specific genes (Cd31, Flk1, Tie1, vWF), a smooth muscle actin (a-Sma) and sinoatrial node-specific genes (Shox2, Tbx18). Chromatin Isolation by RNA Purification showed Moshe activates Nkx2.5 gene expression via direct binding to its promoter region. Of note, Moshe was conserved across species, including human, pig and mouse. Altogether, this study suggests that Moshe is a heart-enriched lncRNA that controls a sophisticated network of cardiogenesis by repressing genes in SHF via Nkx2.5 during cardiac development and may play an important role in ASD.

Application of Immunoprofiling Using Multiplexed Immunofluorescence Staining Identifies the Prognosis of Patients with High-Grade Serous Ovarian Cancer.

Immunoprofiling has an established impact on the prognosis of several cancers; however, its role and definition in high-grade serous ovarian cancer (HGSOC) are mostly unknown. This study is to investigate immunoprofiling which could be a prognostic factor in HGSOC. We produced tumor microarrays of 187 patients diagnosed with HGSOC. We performed a multiplexed immunofluorescence staining using Opal Multiplex IHC kit and quantitative analysis with Vectra-Inform system. The expression intensities of programmed death-ligand 1 (PD-L1), CD4, CD8, CD20, FoxP3, and CK in whole tumor tissues were evaluated. The enrolled patients showed general characteristics, mostly FIGO stage III/IV and responsive to chemotherapy. Each immune marker showed diverse positive densities, and each tumor sample represented its immune characteristics as an inflamed tumor or noninflamed tumor. No marker was associated with survival as a single one. Interestingly, high ratios of CD8 to FoxP3 and CD8 to PD-L1 were related to the favorable overall survival (77 vs. 39 months, 84 vs. 47 months, respectively), and CD8 to PD-L1 ratio was also a significant prognostic factor (HR 0.621, 95% CI 0.420-0.917, p = 0.017) along with well-known clinical prognostic factors. Additionally, CD8 to PD-L1 ratio was found to be higher in the chemosensitive group (p = 0.034). In conclusion, the relative expression levels of CD8, FoxP3, and PD-L1 were significantly related to the clinical outcome of patients with HGSOC, which could be a kind of significant immunoprofiling of ovarian cancer patients to apply for treatment.

CXCL12 is required for stirrup-shaped stapes formation during mammalian middle ear development.

BACKGROUND: The mammalian middle ear comprises a chain of three ossicles-the malleus, incus, and stapes-each of which has a unique morphology for efficiently transmitting sound information. In particular, the stapes, which is attached to the inner ear, is stirrup-shaped with a head and base connected by two crural arches, forming the stapedial foramen, through which the stapedial artery passes. However, how the stapes acquires this critical stirrup shape for association with the stapedial artery during development is not clear. RESULTS: C-X-C motif chemokine ligand 12 (CXCL12) is a chemoattractant essential for cellular movement and angiogenesis. In Cxcl12 -/- embryos, migration of neural crest cells into the prospective middle ear regions and their mesenchymal condensation to form the three ossicles proceed normally in correct alignment with each other and the inner ear. However, in the absence of CXCL12, the stapes loses its stirrup shape and instead exhibits a columnar shape lacking the crural arches and central hole. In addition, although the stapedial artery initially forms during early mesenchymal condensation of the stapes, it degenerates without CXCL12 function. CONCLUSION: CXCL12 plays an essential role in establishing the stirrup-shaped architecture of the stapes, possibly by maintaining the stapedial foramen and stapedial artery throughout development.

TMEM100 is a key factor for specification of lymphatic endothelial progenitors.

BACKGROUND: TMEM100 is identified as a downstream gene of bone morphogenetic protein 9 (BMP9) signaling via activin receptor-like kinase 1 (ALK1), which is known to participate in lymphangiogenesis as well as angiogenesis. TMEM100 has been shown to be important for blood vessel formation and maintenance, but its role in the development of lymphatic vasculature remains unknown. The objective is to investigate the role of TMEM100 in development of the lymphatic system. METHODS AND RESULTS: Global Tmem100 gene deletion was induced by tamoxifen on 10.5 days post-coitus. Tmem100-inducible knockout (iKO) embryos in embryonic days (E)14.5-16.5 exhibited edema and blood-filled enlarged lymphatics with misconnections between veins and lymphatic vessels. For a reciprocal approach, we have generated a novel mouse line in which TMEM100 overexpression (OE) can be induced in endothelial cells by intercrossing with Tie2-Cre driver. TMEM100-OE embryos at E12.5-14.5 exhibited edema with small size and number of lymphatic vessels, the exact opposite phenotypes of Tmem100-iKOs. In Tmem100-iKO embryos, the number of progenitors of lymphatic endothelial cells (LECs) in the cardinal vein was increased, while it was decreased in TMEM100-OE embryos. The activity of NOTCH signaling, which limits the number of progenitors of LECs in the cardinal vein, was decreased in Tmem100-iKO embryos, whereas it was increased in TMEM100-OE embryos. CONCLUSION: TMEM100 plays an important role in the specification of LECs in the cardinal veins, at least in part, by regulating the NOTCH signaling.

Impact of proactive high-throughput functional assay data on BRCA1 variant interpretation in 3684 patients with breast or ovarian cancer.

The clinical utility of BRCA1/2 genotyping was recently extended from the selection of subjects at high risk for hereditary breast and ovary cancer to the identification of candidates for poly (ADP-ribose) polymerase (PARP) inhibitor treatment. This underscores the importance of accurate interpretation of BRCA1/2 genetic variants and of reducing the number of variants of uncertain significance (VUSs). Two recent studies by Findlay et al. and Starita et al. introduced high-throughput functional assays, and proactively analyzed variants in specific regions regardless of whether they had been previously observed. We retrospectively reviewed all BRCA1 and BRCA2 germline genetic test reports from patients with breast or ovarian cancer examined at Asan Medical Center (Seoul, Korea) between September 2011 and December 2018. Variants were assigned pathogenic or benign strong evidence codes according to the functional classification and were reclassified according to the ACMG/AMP 2015 guidelines. Among 3684 patients with available BRCA1 and BRCA2 germline genetic test reports, 429 unique variants (181 from BRCA1) were identified. Of 34 BRCA1 variants intersecting with the data reported by Findlay et al., three missense single-nucleotide variants from four patients (0.11%, 4/3684) were reclassified from VUSs to likely pathogenic variants. Four variants scored as functional were reclassified into benign or likely benign variants. Three variants that overlapped with the data reported by Starita et al. could not be reclassified. In conclusion, proactive high-throughput functional study data are useful for the reclassification of clinically observed VUSs. Integrating additional evidence, including functional assay results, may help reduce the number of VUSs.

Performance evaluation of an amplicon-based next-generation sequencing panel for BRCA1 and BRCA2 variant detection.

BACKGROUND: As next-generation sequencing (NGS) technology matures, various amplicon-based NGS tests for BRCA1/2 genotyping have been introduced. This study was designed to evaluate an NGS test using a newly released amplicon-based panel, AmpliSeq for Illumina BRCA Panel (AmpliSeq panel), for detection of clinically significant BRCA variants, and to compare it to another amplicon-based NGS test confirmed by Sanger sequencing. METHODS: We reviewed BRCA test results done by NGS using the TruSeq Custom Amplicon kit from patients suspected of hereditary breast/ovarian cancer syndrome (HBOC) in 2018. Of those, 96 residual samples with 100 clinically significant variants were included in this study using predefined criteria: 100 variants were distributed throughout the BRCA1 and BRCA2 genes. All target variants were confirmed by Sanger sequencing. Duplicate NGS testing of these samples was performed using the AmpliSeq panel, and the concordance of results from the two amplicon-based NGS tests was assessed. RESULTS: Ninety-nine of 100 variants were detected in duplicate BRCA1/2 genotyping using the AmpliSeq panel (sensitivity, 99%; specificity, 100%). In the discordant case, one variant (BRCA1 c.3627dupA) was found only in repeat 1, but not in repeat 2. Automated nomenclature of all variants, except for two indel variants, was in consensus with Human Genome Variation Society nomenclature. CONCLUSION: Our findings confirm that the analytic performance of the AmpliSeq panel is satisfactory, with high sensitivity and specificity.

Increased intracellular Ca2+ concentrations prevent membrane localization of PH domains through the formation of Ca2+-phosphoinositides.

Insulin resistance, a key etiological factor in metabolic syndrome, is closely linked to ectopic lipid accumulation and increased intracellular Ca2+ concentrations in muscle and liver. However, the mechanism by which dysregulated intracellular Ca2+ homeostasis causes insulin resistance remains elusive. Here, we show that increased intracellular Ca2+ acts as a negative regulator of insulin signaling. Chronic intracellular Ca2+ overload in hepatocytes during obesity and hyperlipidemia attenuates the phosphorylation of protein kinase B (Akt) and its key downstream signaling molecules by inhibiting membrane localization of pleckstrin homology (PH) domains. Pharmacological approaches showed that elevated intracellular Ca2+ inhibits insulin-stimulated Akt phosphorylation and abrogates membrane localization of various PH domain proteins such as phospholipase Cδ and insulin receptor substrate 1, suggesting a common mechanism inhibiting the membrane targeting of PH domains. PH domain-lipid overlay assays confirmed that Ca2+ abolishes the binding of various PH domains to phosphoinositides (PIPs) with two adjacent phosphate groups, such as PI(3,4)P2, PI(4,5)P2, and PI(3,4,5)P3 Finally, thermodynamic analysis of the binding interaction showed that Ca2+-mediated inhibition of targeting PH domains to the membrane resulted from the tight binding of Ca2+ rather than PH domains to PIPs forming Ca2+-PIPs. Thus, Ca2+-PIPs prevent the recognition of PIPs by PH domains, potentially due to electrostatic repulsion between positively charged side chains in PH domains and the Ca2+-PIPs. Our findings provide a mechanistic link between intracellular Ca2+ dysregulation and Akt inactivation in insulin resistance.

Characterization of Severe Acute Respiratory Syndrome Coronavirus 2 Stability in Multiple Water Matrices.

The advent of the global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) necessitates a thorough study of the stability and transmissibility in the environment. We characterized the stability of SARS-CoV-2 in three water matrices: fresh, tap, and seawater. The minimum infective dose of SARS-CoV-2 in Vero cells was confirmed to be 10³ PFU/mL. The stability of SARS-CoV-2 varied according to the water matrix: infective SARS-CoV-2 was undetectable after treatment with fresh water and seawater, but remained detectable for 2 days in tap water, when starting with an initial concentration of 104 PFU/mL. When the starting concentration was increased to 105 PFU/mL, a similar trend was observed. In addition, viral RNA persisted longer than infectious virus in all water matrices. This study was conducted in stagnant water containing a significantly high titer of virus, thus, human-to-human transmission of SARS-CoV-2 through the actual aquatic environment is expected to be rare.

Cell Fate Determination of Lymphatic Endothelial Cells.

The lymphatic vasculature, along with the blood vasculature, is a vascular system in our body that plays important functions in fluid homeostasis, dietary fat uptake, and immune responses. Defects in the lymphatic system are associated with various diseases such as lymphedema, atherosclerosis, fibrosis, obesity, and inflammation. The first step in lymphangiogenesis is determining the cell fate of lymphatic endothelial cells. Several genes involved in this commitment step have been identified using animal models, including genetically modified mice. This review provides an overview of these genes in the mammalian system and related human diseases.

SMAD7 in keratinocytes promotes skin carcinogenesis by activating ATM-dependent DNA repair and an EGFR-mediated cell proliferation pathway.

SMA- and MAD-related protein 7 (SMAD7) is a general inhibitor of transforming growth factor-ß (TGF-ß) signaling that acts through interaction and degradation of TGF-ß receptors. SMAD7 has been demonstrated to be transcriptionally upregulated in chemical-induced skin tumors and TGF-ß-treated normal keratinocytes. To evaluate the function of SMAD7 in skin carcinogenesis in vivo, Smad7 transgenic mice that specifically express either wild-type (WT) SMAD7 (TG-Smad7-WT) or mutant SMAD7 (TG-Smad7-MT) in keratinocytes, as well as Smad7 keratinocyte-specific knockout (Smad72f/2f-K14Cre) mice, were subjected to chemical-induced skin carcinogenesis. WT-SMAD7-expressing transgenic mice showed significantly greater papilloma formation than did non-TG control and Smad7-MT mice. The expression of WT-SMAD7 attenuated DNA damage-induced apoptosis in epidermal keratinocytes by stimulating the ATM-dependent DNA repair pathway. Nonetheless, overexpression of WT-SMAD7 caused a susceptibility to 12-O-tetradecanoylphorbol-13-acetate-induced epidermal hyperproliferation through activation of epidermal growth factor (EGF) signaling. In agreement with the transgenic mouse data, keratinocyte-specific deletion of SMAD7 markedly suppressed the tumor formation by inhibiting ATM and epidermal growth factor receptor (EGFR) signaling. Moreover, specific inhibition of EGFR signaling attenuated the hyperproliferation and tumor formation in TG-Smad7-WT mice. Taken together, these data support a novel role for SMAD7 as a tumor promoter in skin carcinogenesis where SMAD7 stimulates the DNA repair pathway and EGFR signaling activation.

Eliciting unnatural immune responses by activating cryptic epitopes in viral antigens.

Antigenic variation in viral surface antigens is a strategy for escaping the host's adaptive immunity, whereas regions with pivotal functions for infection are less subject to antigenic variability. We hypothesized that genetically invariable and immunologically dormant regions of a viral surface antigen could be exposed to the host immune system and activated by rendering them susceptible to antigen-processing machinery in professional antigen-presenting cells (APCs). Considering the frequent antigen drift and shift in influenza viruses, we identified and used structural modeling to evaluate the conserved regions on the influenza hemagglutinin (HA) surface as potential epitopes. Mutant viruses containing the cleavage motifs of cathepsin S within HA were generated. Immunization of mice showed that the mutant, but not the wild-type virus, elicited specific antibodies against the cryptic epitope. Those antibodies were purified, and specific binding to HA was confirmed. These results suggest that an unnatural immune response can be elicited through the processing of target antigens in APCs, followed by presentation via the major histocompatibility complex, if not subjected to regulatory pathways. By harnessing the antigen-processing machinery, our study shows a proof-of-principle for designer vaccines with increased efficacy and safety by either activating cryptic, or inactivating naturally occurring, epitopes of viral antigens.-Lee, Y. J., Yu, J. E., Kim, P., Lee, J.-Y., Cheong, Y. C., Lee, Y. J., Chang, J., Seong, B. L. Eliciting unnatural immune responses by activating cryptic epitopes in viral antigens.