Suicide associated with COVID-19 infection: an immunological point of view

OBJECTIVE

Coronavirus disease 2019 (COVID-19) is a pandemic and leading cause of death. Beyond the deaths directly caused by the virus and the suicides related to the psychological response to the dramatic changes as socioeconomic related to the pandemic, there might also be suicides related to the inflammatory responses of the infection. Infection induces inflammation as a cytokine storm, and there is an increasing number of studies that report a relationship between infection and suicide.

MATERIALS AND METHODS

We searched the World Health Organization status report and the PubMed database for keywords (COVID-19, suicide, infection, inflammation, cytokines), and reviewed five cytokine pathways between suicide and inflammation using two meta-analyses and two observational studies starting from November 31, 2020, focusing on the relationship between suicide and inflammation by infection. First, we discussed existing evidence explaining the relationship between suicidal behaviors and inflammation. Second, we summarized the inflammatory features found in COVID-19 patients. Finally, we highlight the potential for these factors to affect the risk of suicide in COVID-19 patients.

RESULTS

Patients infected with COVID-19 have high amounts of IL-1β, IFN-γ, IP10, and MCP1, which may lead to Th1 cell response activation. Also, Th2 cytokines (e.g., IL-4 and IL-10) were increased in COVID-19 infection. In COVID-19 patients, neurological conditions, like headache, dizziness, ataxia, seizures, and others have been observed.

CONCLUSIONS

COVID-19 pandemic can serve as a significant environmental factor contributing directly to increased suicide risk; the role of inflammation by an infection should not be overlooked.

Immunoglobulin G4-related Disease of the Genitourinary System: Spectrum of Imaging Findings and Clinical-Pathologic Features

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disease characterized by focal or diffuse organ infiltration of IgG4-bearing plasma cells. The diagnosis of IgG4-RD is based on a combination of clinical, serologic, radiologic, and histopathologic findings. IgG4-RD has been reported to affect almost all organ systems. The kidney is the most frequently involved of the genitourinary organs. The most common renal manifestation of IgG4-RD is IgG4-RD tubulointerstitial nephritis, followed by membranous glomerulonephropathy and, less frequently, obstructive nephropathy involving the renal pelvis, ureter, or retroperitoneum. Renal parenchymal lesions may appear as multiple nodular lesions, diffuse patchy infiltrative lesions, or a single nodular lesion. Multiple small nodular cortical lesions are the most common imaging findings of IgG4-RD involving the kidney. Renal pelvic, sinus, or perinephric lesions can also occur. IgG4-RD involvement of other genitourinary organs including the ureter, bladder, urethra, and male and female reproductive organs is rare compared with kidney involvement but may show variable imaging findings such as a localized mass within or surrounding the involved organ or diffuse enlargement of the involved organ. Imaging findings of IgG4-RD involving the genitourinary system are nonspecific but should be differentiated from inflammatory and neoplastic lesions that mimic IgG4-RD. The online slide presentation from the RSNA Annual Meeting is available for this article. ^©RSNA, 2020.

Peroxisome proliferator-activated receptor δ inhibits Porphyromonas gingivalis lipopolysaccharide-induced activation of matrix metalloproteinase-2 by downregulating NADPH oxidase 4 in human gingival fibroblasts

We investigated the roles of peroxisome proliferator-activated receptor δ (PPARδ) in Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS)-induced activation of matrix metalloproteinase 2 (MMP-2). In human gingival fibroblasts (HGFs), activation of PPARδ by GW501516, a specific ligand of PPARδ, inhibited Pg-LPS-induced activation of MMP-2 and generation of reactive oxygen species (ROS), which was associated with reduced expression of NADPH oxidase 4 (Nox4). These effects were significantly smaller in the presence of small interfering RNA targeting PPARδ or the specific PPARδ inhibitor GSK0660, indicating that PPARδ is involved in these events. In addition, modulation of Nox4 expression by small interfering RNA influenced the effect of PPARδ on MMP-2 activity, suggesting a mechanism in which Nox4-derived ROS modulates MMP-2 activity. Furthermore, c-Jun N-terminal kinase and p38, but not extracellular signal-regulated kinase, mediated PPARδ-dependent inhibition of MMP-2 activity in HGFs treated with Pg-LPS. Concomitantly, PPARδ-mediated inhibition of MMP-2 activity was associated with the restoration of types I and III collagen to levels approaching those in HGFs not treated with Pg-LPS. These results indicate that PPARδ-mediated downregulation of Nox4 modulates cellular redox status, which in turn plays a critical role in extracellular matrix homeostasis through ROS-dependent regulation of MMP-2 activity.

Interference of hepatitis C virus replication in cell culture by antisense peptide nucleic acids targeting the X-RNA

The RNA-dependent RNA polymerase (RdRp) of hepatitis C virus (HCV) is the essential catalytic enzyme for viral genome replication. It initiates minus-strand RNA synthesis from a highly conserved 98-nt sequence, called the X-RNA, at the 3'-end of the plus-strand viral genome. In this study, we evaluated the antiviral effects of peptide nucleic acids (PNAs) targeting the X-RNA. Our in vitro RdRp assay results showed that PNAs targeting the three major stem-loop (SL) domains of X-RNA can inhibit RNA synthesis initiation. Delivery of X-RNA-targeted PNAs by fusing the PNAs to cell-penetrating peptides (CPPs) into HCV-replicating cells effectively suppressed HCV replication. Electrophoretic mobility shift assays revealed that the PNA targeting the SL3 region at the 5'-end of X-RNA dissociated the viral RdRp from the X-RNA. Furthermore, delivery of the SL3-targeted PNA into HCV-infected cells resulted in the suppression of HCV RNA replication without activation of interferon β expression. Collectively, our results indicate that the HCV X-RNA can be effectively targeted by CPP-fused PNAs to block RNA-protein and/or RNA-RNA interactions essential for viral RNA replication and identify X-RNA SL3 as an RdRp binding site crucial for HCV replication. In addition, the ability to inhibit RNA synthesis initiation by targeting HCV X-RNA using antisense PNAs suggests their promising therapeutic potential against HCV infection.

A new HLA-A*24 variant, A*2475, identified by sequence-based typing in the Korean population

A novel human leukocyte antigen (HLA) A*24 allele was identified in the Korean population and designated HLA-A*2475. The HLA-A*2475 allele shows one nucleotide difference from A*24020101 in exon 3 at nucleotide position 575 (T-->C), resulting in an amino acid change, Leu168Arg.

Identification of a new HLA-A*24 variant, A*2474, by sequence-based typing in the Korean population

A novel human leukocyte antigen, A*24 (HLA-A*24), was identified in the Korean population. HLA-A*2474 allele shows one nucleotide difference from A*24020101 in exon 2 at nucleotide position 186 (C --> A), resulting in an amino acid change, Ser38Arg.

Effects of ginsenosides on vanilloid receptor (VR1) channels expressed in Xenopus oocytes

Ginsenosides, or ginseng saponins, are biologically active ingredients of Panax ginseng. Accumulating evidence suggests that ginsenosides can alleviate pain from injections of noxious chemicals, such as capsaicin [Nah et al. (2000)]. In this study we examined the effects of ginsenoside Rc on the capsaicin-induced inward current in Xenopus oocytes that expresses the vanilloid receptor 1 (VR1). Ginsenoside Rc enhanced the capsaicin-induced inward current in a concentration-dependent and reversible manner, but ginsenoside Rc itself elicited no membrane currents. The VR1 antagonist capsazepine almost completely blocked the inward current that was elicited by capsaicin plus ginsenoside Rc. We also tested the effect of seven other fractionated ginsenosides (i.e., Rb1, Rb2, Rd, Re, Rf, Rg1, and Rg2) in addition to ginsenoside Rc. We found that six of them significantly enhanced the inward current that is induced by capsaicin with the following order of potency: Rc > Rf > Rg1 approximately Rd > Rb2 > Rb1. These results show the possibility that the in vivo effect of ginsenosides against capsaicin-induced pain is derived from their modulation of the VR1 channel function.

G alpha(q/11) coupled to mammalian phospholipase C beta 3-like enzyme mediates the ginsenoside effect on Ca(2+)-activated Cl(-) current in the Xenopus oocyte

Recently we demonstrated that ginsenosides, the active ingredients of Panax ginseng, enhanced Ca(2+)-activated Cl(-) current in the Xenopus oocyte through a signal transduction mechanism involving the activation of pertussis toxin-insensitive G protein and phospholipase C (PLC). However, it has not yet been determined precisely which G protein subunit(s) and which PLC isoform(s) participate in the ginsenoside signaling. To provide answers to these questions, we investigated the changes in ginsenoside effect on the Cl(-) current after intraoocyte injections of the cRNAs coding various G protein subunits, a regulator of G protein signaling (RGS2), and G beta gamma-binding proteins. In addition, we examined which of mammalian PLC beta 1-3 antibodies injected into the oocyte inhibited the action of ginsenosides on the Cl(-) current. Injection of G alpha(q) or G alpha(11) cRNA increased the basal Cl(-) current recorded 48 h after, and it further prevented ginsenosides from enhancing the Cl(-) current, whereas G alpha(i2) and G alpha(oA) cRNA injection had no significant effect. The changes following G alpha(q) cRNA injection were prevented when G beta(1)gamma(2) and G alpha(q) subunits were co-expressed by simultaneous injection of the cRNAs coding these subunits. Injection of cRNA coding G alpha(q)Q209L, a constitutively active mutant that does not bind to G beta gamma, produced effects similar to those of G alpha(q) cRNA injection. The effects of G alpha(q)Q209L cRNA injection, however, were not prevented by co-injection of G beta(1)gamma(2) cRNA. Injection of the cRNA coding RGS2, which interacts most selectively with G alpha(q/11) among various identified RGS isoforms and stimulates the hydrolysis of GTP to GDP in active GTP-bound G alpha subunit, resulted in a severe attenuation of ginsenoside effect on the Cl(-) current. Finally, antibodies against PLC beta 3, but not -beta 1 and -beta 2, markedly attenuated the ginsenoside effect examined at 3-h postinjection. These results suggest that G alpha(q/11) coupled to mammalian PLC beta 3-like enzyme mediates ginsenoside effect on Ca(2+)-activated Cl(-) current in the Xenopus oocyte.

Exposure to methyl tertiary butyl ether and benzene in close proximity to service stations

Exposure estimates based solely on proximity to air pollution sources are not sound and require confirmation. Accordingly, since a very limited amount of actual data for this type of exposure estimate is currently available, this study was conducted to provide actual data on residents' exposure to two important gasoline constituents [methyl tertiary butyl ether (MTBE) and benzene] relative to their proximity to roadside service stations. The results confirmed that residents in neighborhoods near service stations are exposed to elevated ambient MTBE and benzene levels compared with those living farther from such a source. However, it was also found that the presumed elevated outdoor benzene levels (a mean of 1.7 ppb) even in close proximity to service stations did not exceed the indoor levels (a mean of 2.2 ppb) of exposure for those living nearby. Regardless of residents' distance from service stations, an indoor source (cigarette smoking) appeared to be the major contributor to their benzene exposure. Conversely, for MTBE, roadside service stations were found to be the major contributor to residents' exposure. In addition, the residents close to the stations were exposed to elevated indoor and outdoor MTBE levels. The sampling period (daytime and nighttime) and season (winter and summer) were additional parameters for the outdoor MTBE and benzene levels and the indoor MTBE levels. Meanwhile, the breathing zone air concentrations of service station attendants for both MTBE and benzene were significantly higher than those of drivers (p < 0.05). In addition, the breathing zone concentrations were significantly higher during summer than during winter for both drivers and attendants (p < 0.05).

Reciprocal expressions of cyclin E and cyclin D1 in hepatocellular carcinoma

Deregulation of the cell cycle by overexpression of G1 cyclins, cyclin E and cyclin D1 genes, has been demonstrated to be a prerequisite for the development of human cancer. Recently, cyclin E is proposed to be sufficient for the progression of the G1 cell cycle without cyclin D1. Here we show that the proposed model system was specifically present in human hepatocellular carcinoma (HCC) unlike other human cancers. Of 31 HCC tissues analyzed, 21 (67.7%) exhibited an overexpression of cyclin E protein. In contrast to cyclin E gene expression, cyclin D1 expression was strongly downregulated in 19 (61.2%) HCCs. Interestingly, 65% of HCC tissues with overexpression of the cyclin E gene exhibited downregulation of cyclin D1, suggesting reciprocal deregulation of these cyclins in the G1 progression of the cell cycle. Southern blot analysis proved the amplification of cyclin E gene in HCC with a high level of overexpression. The present findings suggest that the reciprocal deregulation of cyclin E lacking cyclin D1 expression might play a role in G1 progression and the development of HCC.

Fas-induced expression of chemokines in human glioma cells: involvement of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase

Fas transduces not only apoptotic signals through various pathways but also angiogenic and proinflammatory responses in vivo. Human glioma cells express Fas although sensitivity to Fas-mediated cell death is variable, suggesting that Fas may have functions other than apoptosis in these cells. In this study, we addressed alternative functions of Fas expressed on human gliomas by Fas ligation in three human glioma cell lines, CRT-MG, U373-MG, and U87-MG, and the in vivo expression of Fas and chemokines in human glioblastoma multiforme (GBM). Herein, we demonstrate that: (a) stimulation with agonistic anti-Fas monoclonal antibody CH-11 and human recombinant soluble Fas ligand induces expression of the CC chemokine MCP-1 and the CXC chemokine interleukin-8 by human glioma cell lines at the mRNA and protein levels in a dose- and time-dependent manner; (b) selective pharmacological inhibitors of MEK1 (U0126 and PD98059) and p38 mitogen-activated protein kinase (MAPK) (SB202190) suppress Fas-mediated chemokine expression in a dose-dependent manner; (c) Fas ligation on human glioma cells leads to activation of both extracellular signal-regulated kinases ERK1/ERK2 and p38 MAPK; and (d) GBM samples express higher levels of Fas compared with normal control brain, which correlates with increased interleukin 8 expression. These findings indicate that Fas ligation on human glioma cells leads to the selective induction of chemokine expression, which involves the ERK1/ERK2 and p38 MAPK signaling pathways. Therefore, the Fas-Fas ligand system in human brain tumors may be involved not only in apoptotic processes but also in the provocation of angiogenic and proinflammatory responses.

CXC chemokine receptor 4 expression and function in human astroglioma cells

Chemokines constitute a superfamily of proteins that function as chemoattractants and activators of leukocytes. Astrocytes, the major glial cell type in the CNS, are a source of chemokines within the diseased brain. Specifically, we have shown that primary human astrocytes and human astroglioma cell lines produce the CXC chemokines IFN-gamma-inducible protein-10 and IL-8 and the CC chemokines monocyte chemoattractant protein-1 and RANTES in response to stimuli such as TNF-alpha, IL-1beta, and IFN-gamma. In this study, we investigated chemokine receptor expression and function on human astroglioma cells. Enhancement of CXC chemokine receptor 4 (CXCR4) mRNA expression was observed upon treatment with the cytokines TNF-alpha and IL-1beta. The peak of CXCR4 expression in response to TNF-alpha and IL-1beta was 8 and 4 h, respectively. CXCR4 protein expression was also enhanced upon treatment with TNF-alpha and IL-1beta (2- to 3-fold). To study the functional relevance of CXCR4 expression, stable astroglioma transfectants expressing high levels of CXCR4 were generated. Stimulation of cells with the ligand for CXCR4, stromal cell-derived factor-1alpha (SDF-1alpha), resulted in an elevation in intracellular Ca(2+) concentration and activation of the mitogen-activated protein kinase cascade, specifically, extracellular signal-regulated kinase 2 (ERK2) mitogen-activated protein kinase. Of most interest, SDF-1alpha treatment induced expression of the chemokines monocyte chemoattractant protein-1, IL-8, and IFN-gamma-inducible protein-10. SDF-1alpha-induced chemokine expression was abrogated upon inclusion of U0126, a pharmacological inhibitor of ERK1/2, indicating that the ERK signaling cascade is involved in this response. Collectively, these data suggest that CXCR4-mediated signaling pathways in astroglioma cells may be another mechanism for these cells to express chemokines involved in angiogenesis and inflammation.

SJ-3366, a unique and highly potent nonnucleoside reverse transcriptase inhibitor of human immunodeficiency virus type 1 (HIV-1) that also inhibits HIV-2

We have identified and characterized a potent new nonnucleoside reverse transcriptase (RT) inhibitor (NNRTI) of human immunodeficiency virus type 1 (HIV-1) that also is active against HIV-2 and which interferes with virus replication by two distinct mechanisms. 1-(3-Cyclopenten-1-yl)methyl-6-(3,5-dimethylbenzoyl)-5-ethyl-2,4-pyrimidinedione (SJ-3366) inhibits HIV-1 replication at concentrations of approximately 1 nM, with a therapeutic index of greater than 4 x 10(6). The efficacy and toxicity of SJ-3366 are consistent when evaluated with established or fresh human cells, and the compound is equipotent against all strains of HIV-1 evaluated, including syncytium-inducing, non-syncytium-inducing, monocyte/macrophage-tropic, and subtype virus strains. Distinct from other members of the pharmacologic class of NNRTIs, SJ-3366 inhibited laboratory and clinical strains of HIV-2 at a concentration of approximately 150 nM, yielding a therapeutic index of approximately 20,000. Like most NNRTIs, the compound was less active when challenged with HIV-1 strains possessing the Y181C, K103N, and Y188C amino acid changes in the RT and selected for a virus with a Y181C amino acid change in the RT after five tissue culture passages in the presence of the compound. In combination anti-HIV assays with nucleoside and nonnucleoside RT and protease inhibitors, additive interactions occurred with all compounds tested with the exception of dideoxyinosine, with which a synergistic interaction was found. Biochemically, SJ-3366 exhibited a K(i) value of 3.2 nM, with a mixed mechanism of inhibition against HIV-1 RT, but it did not inhibit HIV-2 RT. SJ-3366 also inhibited the entry of both HIV-1 and HIV-2 into target cells. On the basis of its therapeutic index and multiple mechanisms of anti-HIV action, SJ-3366 represents an exciting new compound for use in HIV-infected individuals.

Major house dust mite allergen, Der p I, activates phospholipase D in human peripheral blood mononuclear cells from allergic patients: involvement of protein kinase C

The major house-dust-mite allergen, Der p I, stimulates the phospholipase D (PLD) in peripheral blood mononuclear cells (PBMC) from allergic patients with maximal responses after 30 min exposure. At 30 min, Der p I stimulated PLD activity by 1.4-fold in mild, 1.6-fold in moderate and 2-fold in severe allergic patients over control values (p < 0.05). When the cells were pretreated for 24 h with phorbol myristate acetate to down-regulate protein kinase C (PKC), PLD stimulation by Der p I was largely abolished. These results indicate that in PBMC from allergic patients, Der p I can stimulate PLD activity, and that PKC activation is involved in this stimulation.

Template requirement and initiation site selection by hepatitis C virus polymerase on a minimal viral RNA template

RNA-dependent RNA polymerase, NS5B protein, catalyzes replication of viral genomic RNA, which presumably initiates from the 3'-end. We have previously shown that NS5B can utilize the 3'-end 98-nucleotide (nt) X region of the hepatitis C virus (HCV) genome as a minimal authentic template. In this study, we used this RNA to characterize the mechanism of RNA synthesis by the recombinant NS5B. We first showed that NS5B formed a complex with the 3'-end of HCV RNA by binding to both the poly(U-U/C)-rich and X regions of the 3'-untranslated region as well as part of the NS5B-coding sequences. Within the X region, NS5B bound stem II and the single-stranded region connecting stem-loops I and II. Truncation of 40 nt or more from the 3'-end of the X region abolished its template activity, whereas X RNA lacking 35 nt or less from the 3'-end retained template activity, consistent with the NS5B-binding site mapped. Furthermore, NS5B initiated RNA synthesis from a specific site within the single-stranded loop I. All of the RNA templates that have a double-stranded stem at the 3'-end had the same RNA initiation site. However, the addition of single-stranded nucleotides to the 3'-end of X RNA or removal of double-stranded structure in stem I generated RNA products of template size. These results indicate that HCV NS5B initiates RNA synthesis from a single-stranded region closest to the 3'-end of the X region. These results have implications for the mechanism of HCV RNA replication and the nature of HCV RNA templates in the infected cells.

ECP level in nasopharyngeal secretions and serum from children with respiratory virus infections and asthmatic children

Infection with respiratory virus has been shown to exacerbate asthma in humans. However, the role of a respiratory virus in the pathogenesis of chronic asthma and/or wheezing in young children has not been clearly defined. It has also been debated whether virus-induced wheezing in young children is one entity and allergic asthma another, or whether they are different expressions of the same disease. The present study was done to compare ECP concentrations in nasopharyngeal secretions and serum from 32 nonasthmatic wheezing children with viral infections (RSV in 15 children; influenza B virus in 17 children detected by immunofluorescence antibody technique), 8 asthmatic children without viral infections, and 13 normal children as the controls to understand the role of eosinophil inflammation. The geometric mean of ECP in nasopharyngeal secretions was significantly higher in asthmatic children than in children with virus-induced wheezing (p < 0.05). ECP levels of nasopharyngeal secretions from children with the virus-induced wheezing were significantly greater than those of the controls. However, there were no significant differences in ECP levels in serum among subjects.

A recombinant hepatitis C virus RNA-dependent RNA polymerase capable of copying the full-length viral RNA

All of the previously reported recombinant RNA-dependent RNA polymerases (RdRp), the NS5B enzymes, of hepatitis C virus (HCV) could function only in a primer-dependent and template-nonspecific manner, which is different from the expected properties of the functional viral enzymes in the cells. We have now expressed a recombinant NS5B that is able to synthesize a full-length HCV genome in a template-dependent and primer-independent manner. The kinetics of RNA synthesis showed that this RdRp can initiate RNA synthesis de novo and yield a full-length RNA product of genomic size (9.5 kb), indicating that it did not use the copy-back RNA as a primer. This RdRp was also able to accept heterologous viral RNA templates, including poly(A)- and non-poly(A)-tailed RNA, in a primer-independent manner, but the products in these cases were heterogeneous. The RdRp used some homopolymeric RNA templates only in the presence of a primer. By using the 3'-end 98 nucleotides (nt) of HCV RNA, which is conserved in all genotypes of HCV, as a template, a distinct RNA product was generated. Truncation of 21 nt from the 5' end or 45 nt from the 3' end of the 98-nt RNA abolished almost completely its ability to serve as a template. Inclusion of the 3'-end variable sequence region and the U-rich tract upstream of the X region in the template significantly enhanced RNA synthesis. The 3' end of minus-strand RNA of HCV genome also served as a template, and it required a minimum of 239 nt from the 3' end. These data defined the cis-acting sequences for HCV RNA synthesis at the 3' end of HCV RNA in both the plus and minus senses. This is the first recombinant HCV RdRp capable of copying the full-length HCV RNA in the primer-independent manner expected of the functional HCV RNA polymerase.

Interleukin-6 (IL-6) production by astrocytes: autocrine regulation by IL-6 and the soluble IL-6 receptor

In the CNS, astrocytes are a major inducible source of interleukin-6 (IL-6). Although IL-6 has beneficial effects in the CNS because of its neurotrophic properties, its overexpression is generally detrimental, adding to the pathophysiology associated with CNS disorders. Many factors have been shown to induce IL-6 expression by astrocytes, particularly the cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1beta). However, the role of IL-6 in its own regulation in astrocytes has not been determined. In this study, we examined the influence of IL-6 alone or in combination with TNF-alpha or IL-1beta on IL-6 expression. IL-6 alone had no effect on IL-6 expression; however, the addition of the soluble IL-6 receptor (sIL-6R) induced IL-6 transcripts. Addition of TNF-alpha or IL-1beta plus IL-6/sIL-6R led to synergistic increases in IL-6 expression. This synergy also occurred in the absence of exogenously added IL-6, attributable to TNF-alpha- or IL-1beta-induced endogenous IL-6 protein production. IL-6 upregulation seen in the presence of TNF-alpha or IL-1beta plus IL-6/sIL-6R was transcriptional, based on nuclear run-on analysis. Experiments were extended to other IL-6 family members to determine their role in IL-6 regulation in astrocytes. Oncostatin M (OSM) induced IL-6 alone and synergized with TNF-alpha for enhanced expression. These results demonstrate that IL-6/sIL-6R and OSM play an important role in the regulation of IL-6 expression within the CNS, particularly in conjunction with the proinflammatory cytokines TNF-alpha and IL-1beta.

Colocalization and membrane association of murine hepatitis virus gene 1 products and De novo-synthesized viral RNA in infected cells

Murine hepatitis virus (MHV) gene 1, the 22-kb polymerase (pol) gene, is first translated into a polyprotein and subsequently processed into multiple proteins by viral autoproteases. Genetic complementation analyses suggest that the majority of the gene 1 products are required for viral RNA synthesis. However, there is no physical evidence supporting the association of any of these products with viral RNA synthesis. We have now performed immunofluorescent-staining studies with four polyclonal antisera to localize various MHV-A59 gene 1 products in virus-infected cells. Immunoprecipitation experiments showed that these antisera detected proteins representing the two papain-like proteases and the 3C-like protease encoded by open reading frame (ORF) 1a, the putative polymerase (p100) and a p35 encoded by ORF 1b, and their precursors. De novo-synthesized viral RNA was labeled with bromouridine triphosphate in lysolecithin-permeabilized MHV-infected cells. Confocal microscopy revealed that all of the viral proteins detected by these antisera colocalized with newly synthesized viral RNA in the cytoplasm, particularly in the perinuclear region of infected cells. Several cysteine and serine protease inhibitors, i.e., E64d, leupeptin, and zinc chloride, inhibited viral RNA synthesis without affecting the localization of viral proteins, suggesting that the processing of the MHV gene 1 polyprotein is tightly associated with viral RNA synthesis. Dual labeling with antibodies specific for cytoplasmic membrane structures showed that MHV gene 1 products and RNA colocalized with the Golgi apparatus in HeLa cells. However, in murine 17CL-1 cells, the viral proteins and viral RNA did not colocalize with the Golgi apparatus but, instead, partially colocalized with the endoplasmic reticulum. Our results provide clear physical evidence that several MHV gene 1 products, including the proteases and the polymerase, are associated with the viral RNA replication-transcription machinery, which may localize to different membrane structures in different cell lines.

Expression of ICAM-1 on conjunctival epithelium and ECP in tears and serum from children with allergic conjunctivitis

BACKGROUND

Conjunctival eosinophilia may be considered to be an indicator of conjunctival allergic disease. The absence of eosinophils on conjunctival scraping, however, cannot rule out the diagnosis of allergic conjunctivitis because eosinophil infiltration may be deeper in conjunctival tissue. Eosinophil cationic protein (ECP) is a toxic product secreted by activated eosinophil as a marker of eosinophil activation. Eosinophil cationic protein concentrations in body fluids correlate with the severity of some allergic diseases. ICAM-1 promotes adhesion of leukocytes to epithelium, endothelium, and upregulates inflammation. Expression of adhesion can be modified by many extracellular and intracellular variables such as proinflammatory cytokines, extracellular matrix proteins, and viral infection.

OBJECTIVE

We investigated whether local eosinophils are only activated in conjunctival epithelium or circulating activated eosinophils are involved in peripheral blood during allergic reaction of the eye. We also demonstrated the possible expression of ICAM-1 on epithelial cells from conjunctival scraping and compared them with soluble ICAM-1 values of serum and tears in children with allergic conjunctivitis and healthy children.

METHODS

Seventeen subjects were selected on the basis of clinical manifestations, history, skin prick test, and total serum IgE. A microcapillary tube was used to collect the tears from the inner canthus. Conjunctival epithelia were obtained by scraping the upper tarsal conjunctiva. The level of ECP was measured by the CAP system, soluble ICAM-1 was measured by ELISA, and ICAM-1 on conjunctival epithelial cells were expressed by the avidine-biotin peroxide complex procedure.

RESULTS

Serum IgE and the eosinophil count were increased in 10 out of 17 patients, positive skin prick tests were positive in 11 patients (Dermatophagoides pternyssinus; 9, Dermatophagoides farinae: 8), and eosinophilia in conjunctival epithelium was in 11 patients (4 patients: >3/HPF, 7 patients: 1-3/HPF). The ECP levels in tears were significantly increased in the patient group (12.0+/-8.0 versus 3.9+/-3.8 microg/mL, P = .01), but not in serum (52.5+/-43.1 versus 28.3+/-25.9 microg/mL). There is significant correlation between the eosinophil count in peripheral blood and on conjunctival epithelium (P = .007, r = .62; n = 25). The ICAM-1 expression score on conjunctival epithelial cells was significantly different between the patient group and controls (patient group: 1.77+/-1.25 versus control: 0.13+/-0.35 ng/mL, P = .002). There was a significant correlation between ICAM-1 expression on conjunctival epithelial cells and the ECP levels of tears (P = .01, r = .58; n = 25). Soluble ICAM-1 levels in serum and tears showed no significant difference between the patient group and controls, and also, there was no correlation between sICAM-1 levels in the serum and tears.

CONCLUSION

Eosinophil cationic protein in tears and ICAM-1 expression scores on conjunctival epithelium showed a significant difference between children with allergic conjunctivitis and the healthy controls, but circulating ECP and sICAM-1 in serum were not significantly different between the two groups. These results may suggest that ICAM-1 is locally upregulated in inflammation, mediating eosinophil activation and migration to conjunctival epithelium, but is not involved as inflammatory mediators in peripheral blood during allergic response in children with allergic conjunctivitis.

Analysis of induced sputum to examine the effects of inhaled corticosteroid on airway inflammation in children with asthma

BACKGROUND

Analysis of induced sputum can be performed safely in children with asthma and is useful for both cellular and biochemical markers of inflammation. Glucocorticosteroid inhalation has become the first line therapy for chronic asthma by suppressing airway inflammation, which produces the decrease of bronchial hyperreactivity and reduces the number of eosinophil in bronchial submucosa.

OBJECTIVE

To determine the characteristics of the inflammatory cells and their markers in sputum and to examine the pharmacokinetic effects of glucocorticoid within 3 hours after inhalation therapy on FEV1 and sputum inflammatory indices in children with clinically defined chronic asthma.

METHODS

Thirty subjects with asthma included 14 current symptomatic asthmatics and 14 normal controls inhaled 4.5% hypertonic saline for 10 minutes by nebulizer. The expectorated sputum were collected from all asthmatics before and 3 hours after corticosteroid inhalation for children with asthma and were reduced by dithiotreitol. Total cell counts and differentials were determined. ECP was measured by CAP system. Interleukin-5, GM-CSF and albumin were measured by double sandwich ELISA.

RESULTS

The mean eosinophil percentage and ECP in induced sputum of asthmatics were significantly higher than that of controls. The induced sputum samples obtained after glucocorticoid inhalation showed a significant reduction in mean eosinophil percentage, but FEV1, IL-5, GM-CSF, albumin, and ECP values were not significantly decreased.

CONCLUSION

The present results in induced sputum may be interpreted to reflect direct steroid action on airways and lack of effect on bone marrow effectors at 3 hours after glucocorticoid inhalation.

Growth-inhibiting effects of Coptis japonica root-derived isoquinoline alkaloids on human intestinal bacteria

The growth-inhibiting activity of Coptis japonica (Makino) root-derived materials toward eight human intestinal bacteria was examined using an impregnated paper disk method and compared to that of four commercially available isoquinoline alkaloids [berberine sulfate (BS), berberine iodide (BI), palmatine chloride (PC), and palmatine sulfate(PS)], as well as that of Thea sinensis leaf-derived epigallocatechin gallate (EGCG). The biologically active constituents of the Coptis extract were characterized as the isoquinoline alkaloids berberine chloride (BC), palmatine iodide (PI), and coptisine chloride (CC) by spectral analysis. The growth responses varied with both chemical and bacterial strain used. In a test using 500 microg/disk, BC and PI produced a clear inhibitory effect against Bifidobacterium longum, Bifidobacterium bifidum, Clostridium perfringens, and Clostridium paraputrificum, whereas weak or no inhibition was observed in Bifidobacterium adolescentis, Lactobacillus acidophilus, Lactobacillus casei, and Escherichia coli. At 1000 microg/ disk, CC revealed weak or no growth inhibition toward all test bacteria, whereas EGCG exhibited weak growth inhibition against only C. perfringens and C. paraputrificum. Among various isoquinoline alkaloids, BC exhibited more potent inhibitory activity toward C. perfringens than BI and BS, whereas the inhibitory effect was more pronounced in PI compared to PC and PS. The Coptis root-derived materials did not promote growth of B. longum and C. perfringens.

Cytokine regulation of CC and CXC chemokine expression by human astrocytes

Chemokines constitute a large family of secreted proteins that function as chemoattractants and activators of leukocytes. Astrocytes, the major glial cell type in the central nervous system (CNS), are a source of chemokine production within diseased brain. As such, we have examined the production of chemokines by human astroglioma cell lines and primary human astrocytes treated with a variety of stimuli, including LPS, TNF-alpha, IFN-gamma and IL-1beta. In addition, IL-6 in conjunction with the soluble IL-6 receptor (sIL-6R), and hybrid IL-6 (H-IL-6), a highly active fusion protein of sIL-6R and IL-6, were tested for their ability to induce chemokine expression. The findings presented herein demonstrate that both human astroglioma cell lines and primary human astrocytes express the CXC chemokines IP-10 and IL-8 and the CC chemokines MCP-1 and RANTES in response to TNF-alpha and IL-1beta. IFN-gamma induced the expression of IP-10, but not of IL-8, MCP-1 or RANTES. Surprisingly, IL-6/sIL-6R and H-IL-6 had little or no effect on chemokine expression in these cells. The effect of TGF-beta on chemokine expression in human astroglioma cell lines and astrocytes was also examined. TGF-beta alone had little or no effect on RANTES, MCP-1 and IL-8 expression; however, TGF-beta synergized with TNF-alpha to enhance MCP-1 expression in both astroglioma cells and primary astrocytes. An inhibitory effect of TGF-beta on TNF-alpha and IL-1beta induced RANTES and IL-8 expression was observed in human astroglioma cells. In contrast, TGF-beta enhanced TNF-alpha and IL-1beta induction ofIL-8 production by human astrocytes. These findings document a complex pattern of chemokine regulation by the pleiotropic cytokine TGF-beta with both enhancing and inhibitory effects.

Non-linear cardiac dynamics and morning dip: an unsound circadian rhythm

The frequency of sudden cardiac death increases in the morning. The relationship between decreased complexity of heart rate dynamics and sudden cardiac death has been documented. An understanding of circadian variation in the complexity of cardiac dynamics may be important to predict and prevent sudden cardiac death. Dynamic 24-h electrocardiographic recordings were obtained from 30 healthy ambulant subjects aged 41-50 years, and the digitized data were partitioned into sections of 30 min duration. For each section, four indexes obtained from separate algorithms of non-linear dynamics of the RR interval--modified correlation dimension, Lyapunov exponent, approximate entropy, and fractal dimension--were calculated. Normalized low-(0.04-0.15 hertz) and high-frequency (> 0.15 hertz) components were also calculated. All four indexes of non-linear dynamics showed a remarkably similar circadian rhythm: a prominent morning dip preceded by a steep decline during the late night, a recovery during the evening and a peak around midnight. In the morning, the low-frequency component rose rapidly with concomitant reduction in the high-frequency component. The complexity of cardiac dynamics decreases significantly in the morning, and this may contribute to the ominously increased rate of cardiac death in the morning hours.

Role of IL-6 and the soluble IL-6 receptor in inhibition of VCAM-1 gene expression

Adhesion molecules such as VCAM-1 and ICAM-1 are increased in the central nervous system (CNS) during inflammatory responses and contribute to extravasation of leukocytes across the blood-brain barrier (BBB) and into CNS parenchyma. Astrocytes contribute to the structural integrity of the BBB and can be induced to express VCAM-1 and ICAM-1 in response to cytokines such as TNF-alpha, IL-1beta, and IFN-gamma. In this study, we investigated the influence of IL-6 on astroglial adhesion molecule expression. IL-6, the soluble form of the IL-6R (sIL-6R), or both IL-6 plus sIL-6R, had no effect on VCAM-1 or ICAM-1 gene expression. Interestingly, the IL-6/sIL-6R complex inhibited TNF-alpha-induced VCAM-1 gene expression but did not affect TNF-alpha-induced ICAM-1 expression. The inhibitory effect of IL-6/sIL-6R complex was reversed by the inclusion of anti-IL-6R and gp130 Abs, demonstrating the specificity of the response. A highly active fusion protein of sIL-6R and IL-6, covalently linked by a flexible peptide, which is designated H-IL-6, also inhibited TNF-alpha-induced VCAM-1 expression. sIL-6R alone was an effective inhibitor of TNF-alpha-induced VCAM-1 due to endogenous IL-6 production. These results indicate that the IL-6 system has an unexpected negative effect on adhesion molecule expression in glial cells and may function as an immunosuppressive cytokine within the CNS.

Natural inhibitors for protein prenyltransferase

Farnesyl protein transferase (FPT) catalyzes the posttranslational farnesylation of the cysteine residue located in the carboxyl-terminal tetrapeptide of the Ras oncoprotein. Prenylation of this residue is essential for membrane association and cell transforming activities of Ras. Inhibitors of FPT have been demonstrated to inhibit Ras-dependent cell transformation and thus represent a potential therapeutic strategy for the treatment of human cancers (1). In the present study, the inhibitory principles for protein prenyltransferases were isolated and identified from Ganoderma lucidum and garlic. The inhibitors from Ganoderma lucidum were identified as ganoderic acid A and ganoderic acid C by comparison with the reported spectral data. Ganoderic acid A has an IC50 value of 100 microM against FPT and its methyl ester (methyl ganoderate A) has an IC50 value of 38 microM for the same enzyme. These inhibitors appear to be competitive with farnesyl pyrophosphate (FPP), and Ki values of ganoderic acid A and methyl ganoderate A are 54 microM and 20 microM, respectively. The inhibitors from garlic were identified as diallyl thiosulfinate (allicin), methyl allyl thiosulfinate, and allyl methyl thiosulfinate. These inhibitors are more effective against geranylgeranyl protein transferase (GGPT) than FPT and IC50 values of allicin, methyl allyl thiosulfinate, and allyl methyl thiosulfinate for GGPT were 43 microM, 57 microM, and 53 microM, respectively. Methyl allyl thiosulfinate appears to be competitive with geranylgeranyl pyrophosphate (GGPP) and its Ki was determined to be 15 microM. The molecular structures of triterpenes and thiosulfinates are expected to be useful in designing lead compounds for new potent antitumour agents.

Interleukin-6 receptor-interleukin-6 fusion proteins with enhanced interleukin-6 type pleiotropic activities

An sIL-6R/IL-6 chimera, directly fusing the natural forms of soluble IL-6 receptor and IL-6, as found in human body fluids, was produced in transfected human cells. The secreted p85 glycoprotein was active at a concentration of 120 pM to produce growth-arrest and spindleoid differentiation of murine melanoma F10.9 cells, which do not respond to IL-6 alone. This fusion protein was as active as the yeast-produced p56 fusion protein containing a shortened sIL-6R, linked through a flexible peptide chain to IL-6 (Hyper IL-6). The concentration of Hyper IL-6 needed to arrest the growth of F10.9 cells was much lower than that needed of a combination of IL-6 and sIL-6R, added separately. Hyper IL-6 was also more active than IL-6 in stimulating growth of murine plasmacytoma T1165 cells, the half maximal stimulation being obtained at 2 pM Hyper IL-6 versus 23 pM for IL-6. In order to evaluate the effect of the fused sIL-6R/IL-6 proteins on human hematopoietic primitive progenitor cells, they were added to suspension cultures of CD34+ cells from human cord blood in addition to both flt3/flk2 ligand (FL) and stem cell factor (SCF). Fused sIL-6R/IL-6 produced a marked stimulation of cell expansion and a marked increase in the number of colony forming units when subsequently plated in semi-solid medium with IL-3, GM-CSF, SCF and erythropoietin. Ex-vivo maintenance and expansion of early progenitor cells in bone marrow transplantation protocols may be a potential application for the sIL-6R/IL-6 chimeric glycoproteins.

The coat protein of turnip crinkle virus is involved in subviral RNA-mediated symptom modulation and accumulation

Some satellite (sat-) and defective interfering (DI) RNAs associated with plant viruses intensify or ameliorate the symptoms of the virus. We recently demonstrated that the TCV coat protein (CP) is involved in symptom modulation by sat-RNA C. Two additional subviral RNAs have now been tested for effect of the CP on symptom modulation. DI RNA G, which normally intensifies the symptoms of TCV, is able to attenuate symptoms if the TCV CP is replaced with the CP of cardamine chlorotic fleck virus. DI RNA G had no effect on the symptoms of TCV with a single base alteration in the CP open reading frame, unlike sat-RNA C, which was able to ameliorate the symptoms of the mutant TCV. Using a hybrid sat-RNA constructed from sat-RNA C and TCV (which shares a similar 3'-end region with DI RNA G), the 3'-terminal 53 bases of sat-RNA C were found to be involved in symptom attenuation, which was directly correlated with the lack of detectable viral genomic RNA in whole plants. Sat-RNA D had no effect on the symptoms of mutant or wild-type TCV. The accumulation of TCV subviral RNAs in plants and protoplasts was also found to be strongly influenced by the presence or absence of the wild-type TCV CP.

Characterization of human immunodeficiency virus type 1 integrase mutants expressed in Escherichia coli

The eight mutant integrase (IN) proteins of human immunodeficiency virus type (HIV-1), which have a single point mutation at a highly conserved central region, were prepared, and characterized in terms of their endonucleolytic activities and disintegration activities in vitro. Mutation of two highly conserved amino acids, Asp116 or Glu152, leads to complete loss of both the activities, suggesting that these two amino acids are directly associated with enzymatic functions. In addition, the mutant of the position Ser147 was found to have highly depressed endonucleolytic activity showing that the reaction was very delayed in comparison with that of the wild type. However, significant disintegration was detected in the mutant Ser147, indicating that the enzymatic mechanisms of the endonucleolytic and disintegration activities are not exactly reverse. The integrase protein with a mutation at the conserved amino acid Asn117 or Gly118 had a slight loss of the endonucleolytic activity, while a mutation at the three positions, Tyr143, Ser153, and Lys159, had no detectable effect on their enzymatic activities. These results indicate that only a few of the conserved amino acids are critical for enzymatic activities.

Unmasking by soluble IL-6 receptor of IL-6 effect on metastatic melanoma: growth inhibition and differentiation of B16-F10.9 tumor cells

Interleukin-6 (IL-6) inhibits the growth of melanocytes and of early stage melanoma cells, but not that of advanced melanoma cells. The in vitro IL-6 response can be restored in the highly metastatic melanoma B16-F10.9 by addition of recombinant soluble IL-6 receptor alpha-chain (sIL-6R). The F10.9 cells then undergo irreversible growth-arrest and show increased adherence with changes from epithelioid to spindleoid morphology. The sIL-6R is required for IL-6 to induce a sustained activation of the various Stat transcription factors which bind to specific IL-6 inducible enhancers. The sIL-6R and IL-6 combination causes an increase in the level of the anti-oncogenic transcription factor IRF-1 protein and DNA-binding, which remain elevated for 24 h. The promoter activity of the anti-oncogenic p21/Waf-1/Cip-1 gene is induced and accumulation of the p21 protein is observed. These results illustrate the potent agonist activity of sIL-6R on molecular pathways which could mediate the growth-arrest and differentiation of the metastatic melanoma cells. Previously observed antimetastatic effects of IL-6 therapy in mice bearing F10.9 tumors may be at least partly due to direct growth inhibition and differentiation elicited by sIL-6R present in biological fluids.

A preceding airway reaction to one allergen may lead to priming of the airway responses to another allergen

This study aimed to determine whether a preceding airway response to one allergen leads to priming of the airway responses to another allergen. Twelve asthmatic children who had positive prick tests to two allergens, Dermatophagoides pteronyssinus (D.p.) and German cockroach (CR), participated in a randomized, placebo-controlled crossover study. We performed two consecutive inhalation challenges, D.p. challenge being followed 48 h later by CR challenge. The effect of initial (D.p.) challenge on the early and late airway responses to the subsequent (CR) challenge (CR2) was examined by comparing the responses with those to CR challenge preceded by sham challenge (CR1). The geometric mean PD20 of CR allergen in the CR2 was 2.8 BU (breath unit) (range of 1 SD; 0.77-10.4), which was 12.0-fold less than that (33.7 BU, 10.8-105.2) in the CR1. The administration of a 6.1-fold less dose (8.9 BU, 2.7-28.8) in the CR2 than in the CR1 (54.5 BU, 44.1-69.3) provoked a similar degree of late-phase reactions (18.7 +/- 7.3% vs 15.8 +/- 9.6%). Our data indicated that the early- and late-phase reactions to CR challenge were augmented by the preceding reaction to D.p. This suggests that a preceding airway response to one allergen may lead to priming, with enhancement of the early and late airway responses to the subsequent challenge with another allergen.

A comparison of serum haptoglobin levels between acute exacerbation and clinical remission in asthma

BACKGROUND

Bronchial asthma is characterized by airway inflammation, which underlies the phenomenon of bronchial hyperresponsiveness. The concentration of serum haptoglobin (Hp), one of the acute phase reactant proteins, has been reported to correlate with bronchial hyperresponsiveness. The extent to which bronchoconstriction or airway inflammation contributes to airflow obstruction of exacerbation is presumed to determine the responsiveness to the initial bronchodilator therapy.

OBJECTIVE

To see whether the Hp levels vary with the disease status of asthma, and also to test whether the Hp level at an acute exacerbation (AE) is correlated with the degree of response to initial bronchodilator therapy.

METHODS

We measured serum Hp levels in 50 children with asthma at the times of an AE and a clinical remission(CR), and analysed the data according to the response to the initial bronchodilator therapy at AE.

RESULTS

The serum concentration of Hp at AE (228.5 +/- 80.8 mg/dl, mean +/- SD) was significantly (P < 0.01) higher than that at CR (152.3 +/- 49.8 mg/dl) in the total study population. The difference of Hp levels between AE and CR was more marked (101.7 +/- 82.2 mg/dl) in the subjects (n = 19) who responded poorly (post-bronchodilator FEV1 < 75% predicted) to the initial bronchodilator therapy at AE than that (61.0 +/- 56.5 mg/dl) of those (n = 31) who responded well (post-bronchodilator FEV1 > or = 75% predicted). The Hp level at AE correlated with the degree of response to initial bronchodilator therapy (r = (-)0.36, P < 0.05), whereas it had no relationship with the severity of exacerbation (r = 0.04, P = 0.79).

CONCLUSION

Our results showed that Hp levels may be increased at the time of exacerbation in a given asthma patient. The finding that the elevation of Hp level at AE is more marked in the cases with poor response to initial bronchodilator therapy at AE suggests that the increased Hp level at AE in asthma might reflect the degree of airway inflammation.

A soluble interleukin 6 receptor isolated from conditioned medium of human breast cancer cells is encoded by a differentially spliced mRNA

The human interleukin 6 receptor (IL-6R) is expressed on cells as a transmembrane protein of 80 kDa (gp80, ligand binding unit), or as a smaller soluble counterpart (sIL-6R, approximately 55 kDa). Recombinant or natural sIL-6Rs bind IL-6 and stimulate biological activity by association with the signal transducing subunit gp130 at the cell surface. The origin of sIL-6Rs is not clear. Haematopoietic cells express, in addition to the gp80 mRNA, an IL-6R mRNA where the transmembrane domain is spliced out, predicting a shorter protein with a modified basic sequence at the C-terminus. We show that the spliced mRNA is expressed in human T47D breast carcinoma cells and soluble IL-6R protein is indeed secreted by these cells. An antibody against the C-terminus of the spliced protein detects a 55-65 kDa glycosylated species in sIL-6R purified from T47D supernatant by classical and immunoaffinity chromatography. The spliced T47D IL-6R, glycosylated or after removal of O- and N-linked polysaccharides, has the same size as a recombinant spliced IL-6R from CHO cells. The recombinant spliced IL-6R acts on cells as an IL-6 agonist to stimulate transcription from IL-6 inducible enhancers.

Open reading frames of turnip crinkle virus involved in satellite symptom expression and incompatibility with Arabidopsis thaliana ecotype Dijon

Carmoviruses are single-stranded, single component RNA viruses that include turnip crinkle virus (TCV) and the recently discovered cardamine chlorotic fleck virus (CCFV). Full-length, biologically active cDNAs were constructed for the TCV-M isolate and the Blue Lake isolate of CCFV. Using chimeric viruses constructed between isolates of TCV that produce mild or severe symptoms when coinoculated with a virulent satellite RNA, a Glu residue at position 1,144 in the polymerase open reading frame was identified as being involved in satellite-mediated symptom expression. To analyze viral determinants involved in resistance, chimeric viruses with precisely exchanged open reading frames were produced between TCV, which does not infect the Arabidopsis thaliana ecotype Dijon (Di-0), and CCFV, which can infect Di-0, TCV with the coat protein of CCFV was able to systemically infect Di-0 although whole plant hybridizations revealed that the hybrid virus spread more slowly than either of the two parental viruses. These results indicate that the two parental viruses. These results indicate that the coat protein is an important viral determinant in the resistance of Di-0 to TCV.

Symptom attenuation by a normally virulent satellite RNA of turnip crinkle virus is associated with the coat protein open reading frame

Many satellite RNAs (sat-RNAs) can attenuate or intensify the symptoms produced by their helper virus. Sat-RNA C, associated with turnip crinkle virus (TCV), was previously found to intensify the symptoms of TCV on all plants in which TCV produced visible symptoms. However, when the coat protein open reading frame (ORF) of TCV was precisely exchanged with that of cardamine chlorotic fleck virus, sat-RNA C attenuated the moderate symptoms of the chimeric virus when Arabidopsis plants were coinoculated with the chimeric virus. Symptom attenuation was correlated with a reduction in viral RNA levels in inoculated and uninoculated leaves. In protoplasts, the presence of sat-RNA C resulted in a reduction of approximately 70% in the chimeric viral genomic RNA at 44 hr postinoculation, whereas the sat-RNA wa consistently amplified to higher levels by the chimeric virus than by wild-type TCV. TCV with a deletion of the coat protein ORF also resulted in a similar increase in sat-RNA C levels in protoplasts, indicating that the TVC coat protein, or its ORF, downregulates the synthesis of sat-RNA C. These results suggest that the coat protein or its ORF is a viral determinant for symptom modulation by sat-RNA C, and symptom attenuation is at least partly due to inhibition of virus accumulation.

Epitope peptides from interleukin-6 receptor which inhibit the growth of human myeloma cells

A panel of monoclonal antibodies against the soluble IL-6 receptor was used to search for linear epitopes by a Pepscan analysis. Two such epitopes were found and the corresponding peptides were synthesized chemically. The peptides were active to inhibit the IL-6 dependent growth of human multiple myeloma cell line and the effect of IL-6 on growth of murine hybridoma cells. The epitope-defined, antagonist peptides reduced the transduction of the IL-6 signal which activates binding of Stat transcription factors to specific enhancers, but did not affect IL-6 binding. These effects were not seen with several other peptides from the IL-6 receptor sequence. A computer three-dimensional model of the IL-6 receptor complex was built and indicates that the antagonist peptides define one of the two possible sites of interaction between the domain-II of the IL-6 receptor molecule and that of the gp130 molecule within the hexameric receptor assembly.

Involvement of a stem-loop structure in the location of junction sites in viral RNA recombination

Recombination between RNAs associated with turnip crinkle virus is thought to occur during plus-strand synthesis at motifs resembling the 5'-ends of genomic, subgenomic and satellite RNAs. Common structural regions encompassing the motifs have been found for major crossover sites on two different minus-strand templates, with junctions preferentially located in a single-stranded region at the 3' base of a hairpin. Base changes, deletions and compensatory alteration constructed in and around the hairpin in the region of the turnip crinkle virus genomic RNA involved in recombination support the importance of the hairpin for normal crossover site selection. This region of the genomic RNA is also important for replication of the viral genomic RNA in plants and protoplasts, suggesting a common link between sequences required for recombination and viral replication.