Interferon-α (IFNα) neurotoxicity

Clinical studies indicate that increased central nervous system (CNS) interferon-alpha (IFNα) is associated with cognitive dysfunction in a wide variety of conditions. This has perhaps been best studied in HIV-associated neurocognitive disorders (HAND). These findings on IFNα neurotoxicity have been corroborated in animal studies. Probably the best demonstration of the neurotoxicity of IFNα was through the use of a mouse model of HAND, where it was shown that blocking IFNα with neutralizing antibodies prevented behavioral deficits and associated histopathological effects. In vitro studies have demonstrated a dose dependent, detrimental effect of IFNα on neuronal dendrites. Development of therapeutics that block IFNα may prove to be an effective treatment of HAND and other inflammatory conditions where there is increased CNS IFNα.     

Modification of Hyaluronan by Heavy Chains of Inter-α-Inhibitor in Idiopathic Pulmonary Arterial Hypertension

We previously reported an altered hyaluronan (HA) metabolism in idiopathic pulmonary arterial hypertension (IPAH) lung tissue and cultured smooth muscle cells. Hyaluronan was present in the smooth muscle cell layer surrounding the pulmonary vasculature and in plexigenic lesions. Additionally, cultured pulmonary artery smooth muscle cells produced spontaneous HA “cable” structures, without additional stimuli, that were leukocyte-adhesive. We now present evidence that the HA that accumulates in IPAH plexigenic lesions is a pathological form of HA in which heavy chains (HCs) from the serum-derived proteoglycan inter-α-inhibitor are covalently attached to the HA backbone to form a pathological HC-HA complex. CD45-positive leukocytes were identified within these HC-HA matrices. Elevated mRNA levels of the enzyme that transfers HCs to HA, known as tumor necrosis factor-stimulated gene 6, were detected in IPAH lung tissue.     

Role of MicroRNA Modulation in the Interferon-α/Ribavirin Suppression of HIV-1 In Vivo

Background

Interferon-α (IFN-α) treatment suppresses HIV-1 viremia and reduces the size of the HIV-1 latent reservoir. Therefore, investigation of the molecular and immunologic effects of IFN-α may provide insights that contribute to the development of novel prophylactic, therapeutic and curative strategies for HIV-1 infection. In this study, we hypothesized that microRNAs (miRNAs) contribute to the IFN-α-mediated suppression of HIV-1. To inform the development of novel miRNA-based antiretroviral strategies, we investigated the effects of exogenous IFN-α treatment on global miRNA expression profile, HIV-1 viremia, and potential regulatory networks between miRNAs and cell-intrinsic anti-HIV-1 host factors in vivo.

Methods

Global miRNA expression was examined in longitudinal PBMC samples obtained from seven HIV/HCV-coinfected, antiretroviral therapy-naïve individuals before, during, and after pegylated interferon-α/ribavirin therapy (IFN-α/RBV). We implemented novel hybrid computational-empirical approaches to characterize regulatory networks between miRNAs and anti-HIV-1 host restriction factors.

Results

miR-422a was the only miRNA significantly modulated by IFN-α/RBV in vivo (p<0.0001, paired t test; FDR<0.037). Our interactome mapping revealed extensive regulatory involvement of miR-422a in p53-dependent apoptotic and pyroptotic pathways. Based on sequence homology and inverse expression relationships, 29 unique miRNAs may regulate anti-HIV-1 restriction factor expression in vivo.

Conclusions

The specific reduction of miR-422a is associated with exogenous IFN-α treatment, and likely contributes to the IFN-α suppression of HIV-1 through the enhancement of anti-HIV-1 restriction factor expression and regulation of genes involved in programmed cell death. Moreover, our regulatory network analysis presents additional candidate miRNAs that may be targeted to enhance anti-HIV-1 restriction factor expression in vivo.     

Reagents for Modification of Protein–Nucleic Acid Complexes: III.1Site-Specific Photomodification of Elongation Complex of DNA Polymerase β with Arylazide Derivatives of Primers Sensitized with Fluorescent ATP γ-Amides

ATP -amides containing in -N-position 1-methylpyrene, 9-methylanthracene, 10-chloro-9-methyl-anthracene, and 3-methylperylene residues were synthesized and characterized. These compounds were used as sensitizers of site-specific photomodification of the reconstituted elongating complex of the mammalian DNA polymerase . The photomodification was carried out with the use of photoaffinity reagents, which were synthesized in situby the 5"-³²P-labeled primers extension with photoreactive analogues of dCTP containing in the exo-N-position of cytosine various perfluoroarylazide groups. The effect of structures of the sensitizers and photoreactive reagents on the efficiency and selectivity of photocrosslinking of primers to the enzyme and template, as well as formation of a number of other photomodification products was studied. It was shown that the sensitizers containing 10-chloro-9-methylanthracene and 3-methylperylene residues allow one to obtain photocrosslinks under such irradiation conditions when photomodification in their absence is not essentially observed.     

Effect of Recombinant Interferon-α2b (Laferon) on Transport of Sodium Ions in Human Neuroblastoma Cells

To elucidate molecular mechanisms of neurotropic action of a recombinant interferon, IFN-2b (laferon), its effect on transport of ²²Na⁺ through the membrane of cultured human neuroblastoma cells (line IMR 32) was investigated. Within the first minutes after treatment with IFN-2b, the influx of ²²Na⁺ ions was reduced by 20%, as compared with the control. Depolarization of the plasma membrane by a mixture of veratrine and scorpion (Leiurus quinquestriatus) toxin (200 and 10 g/ml, respectively) increased this flux by 50% in the control and by 70% in the IFN-2b-treated cells. A blocker of voltage-operated sodium channels, tetrodotoxin (TTX, 4 · 10^-7 M), suppressed the inward flux of ²²Na⁺ ions (completely in the control cells and by 75% in the IFN-2b-treated cells). The influx of ²²Na⁺ ions into neuroblastoma cells depended on the concentration of IFN-2b in the incubation medium, reaching a maximum at concentrations of 600-1000 IU/ml. This allows us to suggest that entry of Na⁺ ions into neuroblastoma cells caused by IFN-2b is basically performed through voltage-operated TTX-sensitive sodium channels.     

Interferon-β for treatment of rheumatoid arthritis?

IFN-β treatment is emerging as a potentially effective form of therapy in various immune-mediated conditions. The present review addresses the possible role of IFN-β in immune-mediated diseases such as multiple sclerosis and rheumatoid arthritis. Several placebo-controlled trials are discussed, as are the available immunological data that are relevant to this field. Review of these data provides evidence that IFN-β has some beneficial therapeutic effect in patients with relapsing-remitting multiple sclerosis and might also have antirheumatic potential. This notion is supported by recent studies showing a critical role for IFN-β in bone homeostasis.     

Synthesis and Transmembrane Transport Studies of Lipophilic Adenosine 5′-Triphosphate Derivatives

Abstract

The preparation of acyl adenosine 5′-triphosphates as potential membrane permeable prodrugs is presented. The interaction of myristoyl- and cholesteryloxy-carbonyl-ATP with liposomes as model membranes and the release of ATP inside these vesicles was investigated using an enzymatic assay as well as ³¹P-NMR spectroscopy.     

Synthesis of β-Diketone DNA Derivatives for Affinity Modification of Proteins

Russian Journal of Bioorganic Chemistry - Diketone DNA derivatives have been proposed to modify the guanidine group of Arg in proteins. The β-diketo group at the C2' atom of the sugar...     

Alpha-Galactosyl trisaccharide epitope: Modification of the 6-primary positions and recognition by human anti-αGal antibody

Galactose oxidase (EC 1.1.3.9, GAO) was used to convert the C-6′ OH of Galβ(1 → 4)Glcβ–OBn (5) to the corresponding hydrated aldehyde (7). Chemical modification, through dehydratative coupling and reductive amination, gave rise to a small library of Galβ(1 → 4)Glcβ–OBn analogues (9a–f, 10, 11). UDP-[6-³H]Gal studies indicated that α1,3-galactosyltransferase recognized the C-6′ modified Galβ(1 → 4)Glcβ–OBn analogues (9a–f, 10, 11). Preparative scale reactions ensued, utilizing a single enzyme UDP-Gal conversion as well as a dual enzymatic system (GalE and α1,3GalT), taking full advantage of the more economical UDP-Glc, giving rise to compounds 6, 15–22. Galα(1 → 3)Galβ(1 → 4)Glcβ–OBn trisaccharide (6) was produced on a large scale (2 g) and subjected to the same chemoenzymatic modification as stated above to produce C-6″ modified derivatives (23–30). An ELISA bioassay was performed utilizing human anti-αGal antibodies to study the binding affinity of the derivatized epitopes (6, 15–30). Modifications made at the C-6′ position did not alter the IgG antibody's ability to recognize the unnatural epitopes. Modifications made at the C-6″ position resulted in significant or complete abrogation of recognition. The results indicate that the C-6′ OH of the αGal trisaccharide epitope is not mandatory for antibody recognition. Published in 2004. This revised version was published online in July 2006 with corrections to the Cover Date.     

Longitudinal Study of a Human Drug-Induced Model of Autoantibody to Cytoplasmic Rods/Rings following HCV Therapy with Ribavirin and Interferon-α

Background

A novel pattern in the indirect immunofluorescence antinuclear antibody assay on HEp-2 cells (IIF-HEp-2) characterized by cytoplasmic rods and rings (RR) was reported in HCV patients, but stringent disease specificity studies and longitudinal analysis are lacking. We investigated the clinical significance of anti-RR in an HCV cohort with up to a 12-month treatment follow up.

Methodology/Results

597 patients (342 HCV, 55 HCV/HIV, 200 non-HCV) were screened and titered for anti-RR. Serial samples were available from 78 of 176 treated and 27 of 166 untreated patients. Anti-RR was detected in 14.1% of 342 HCV patients, 9.1% of 55 HCV/HIV, 3.4% of 29 Hepatitis B, and none of 171 non-HCV (p<0.0001; HCV versus non-HCV). Anti-RR was present in 38% of 108 patients receiving interferon-α/ribavirin, but none in 26 receiving either interferon-α or ribavirin, or 166 untreated patients (p<0.0001). Other IIF-HEp-2 patterns were more frequently associated with interferon-α treatment alone (52.2%) as compared to interferon-α/ribavirin (25%), ribavirin alone (33.3%), and no therapy (26.5%). Anti-RR frequency was not associated with sex, age, ethnicity, HCV genotype or viral load. Anti-RR occurred only after initiation of treatment, beginning as early as 1 month (6%), but by the sixth month >47% tested positive for anti-RR. The anti-RR titer generally increased with sustained treatment and remained high in 53% of patients. After treatment, anti-RR titer was negative in 41%. Non-responders to HCV therapy were 77% in anti-RR-positive versus 64% in anti-RR-negative patients. Response to treatment was not associated with anti-RR titer or the dynamics of anti-RR reactivity during and after treatment.

Conclusions

The exquisite association of anti-RR reactivity with combined interferon-α/ribavirin therapy in HCV patients represents a unique model for drug-induced autoantibody generation in humans as demonstrated by the fact that a significant fraction of patients who have anti-RR during therapy becomes anti-RR-negative after completion of therapy.     

Mutant of φX174 Accessible to Host-controlled Modification

A proflavine-induced X174 mutant was isolated, X174 sB1, which is accessible to restriction and modification by B-host specificity, but not by K-host specificity.     

Osteocytes Produce Interferon-β as a Negative Regulator of Osteoclastogenesis

Osteoclastogenesis is controlled by osteocytes; osteocytic osteoclastogenesis regulatory molecules are largely unknown. We searched for such factors using newly developed culture methods. Our culture system mimics the three-dimensional cellular structure of bone, consisting of collagen gel-embedded osteocytic MLO-Y4 cells, stromal ST2 cells on the gel as bone lining cells, and bone marrow cells. The gel-embedded MLO-Y4 cells inhibited the osteoclastogenesis induced by 1,25(OH)₂D₃ without modulating receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) production by ST2 cells, despite MLO-Y4 cells supported osteoclastogenesis in the absence of ST2 cells. In the bone marrow cell culture, the conditioned medium from MLO-Y4 cells decreased the capability of osteoclastic differentiation from the cells induced by macrophage colony-stimulating factor. This decreased capability was concomitant with an increase in protein kinase R mRNA expression and an inhibition of c-Fos translation. These changes were partially normalized by the simultaneous addition of an anti-interferon (IFN)-β neutralizing antibody to MLO-Y4 cell conditioned medium. To study primary osteocytes, we prepared non-osteocytic cell-free osteocyte-enriched bone fragments (OEBFs). When osteoclast precursors were induced by macrophage colony-stimulating factor in the presence of OEBFs, the generated cells exhibited a diminished capacity for osteoclastogenesis. OEBFs prepared from OPG-knock-out mice exhibited a similar effect, indicating OPG-independent inhibition. The addition of anti-IFN-β neutralizing antibody during the co-culture with OEBFs partially recovered the osteoclastogenic potential of the generated cells. The MLO-Y4 cells and OEBFs expressed IFN-β mRNA. Although osteocytic RANKL is known to be important for osteoclastogenesis, our data suggest that osteocytes also produce IFN-β as an inhibitor of osteoclastogenesis.     

Temperature and Electrolyte Optimization of the α-Hemolysin Latch Sensing Zone for Detection of Base Modification in Double-Stranded DNA

The latch region of the wild-type protein pore α-hemolysin (α-HL) constitutes a sensing zone for individual abasic sites (and furan analogs) in double-stranded DNA (dsDNA). The presence of an abasic site or furan within a DNA duplex, electrophoretically captured in the α-HL vestibule and positioned at the latch region, can be detected based on the current blockage prior to duplex unzipping. We investigated variations in blockage current as a function of temperature (12–35°C) and KCl concentration (0.15–1.0 M) to understand the origin of the current signature and to optimize conditions for identifying the base modification. In 1 M KCl solution, substitution of a furan for a cytosine base in the latch region results in an ∼8 kJ mol⁻¹ decrease in the activation energy for ion transport through the protein pore. This corresponds to a readily measured ∼2 pA increase in current at room temperature. Optimal resolution for detecting the presence of a furan in the latch region is achieved at lower KCl concentrations, where the noise in the measured blockage current is significantly lower. The noise associated with the blockage current also depends on the stability of the duplex (as measured from the melting temperature), where a greater noise in the measured blockage current is observed for less stable duplexes.     

Pegylated Interferon-α2a Inhibits Proliferation of Human Liver Cancer Cells In Vitro and In Vivo

Purpose

We investigated the effects of pegylated interferon-α2a (PEG-IFN-α2a) on the growth of human liver cancer cells.

Methods

The effect of PEG-IFN-α2a on the proliferation of 13 liver cancer cell lines was investigated in vitro. Cells were cultured with medium containing 0–4,194 ng/mL of PEG-IFN-α2a, and after 1, 2, 3, or 4 days of culture, morphologic observation and growth assay were performed. After hepatocellular carcinoma (HCC) cells (HAK-1B and KIM-1) were transplanted into nude mice, various doses of PEG-IFN-α2a were subcutaneously administered to the mice once a week for 2 weeks, and tumor volume, weight, and histology were examined.

Results

PEG-IFN-α2a inhibited the growth of 8 and 11 cell lines in a time- and dose-dependent manner, respectively, although the 50% growth inhibitory concentrations of 7 measurable cell lines on Day 4 were relatively high and ranged from 253 ng/mL to 4,431 ng/mL. Various levels of apoptosis induction were confirmed in 8 cell lines. PEG-IFN-α2a induced a dose-dependent decrease in tumor volume and weight, and a significant increase of apoptotic cells in the tumor. Subcutaneous administration of clinical dose for chronic hepatitis C (3 μg/kg, 0.06 μg/mouse) was effective and induced about 30-50% reduction in the tumor volume and weight as compared with the control.

Conclusions

Although in vitro anti-proliferative effects of PEG-IFN-α2a were relatively weak, PEG-IFN-α2a induced strong anti-tumor effects on HCC cells in vivo. The data suggest potential clinical application of PEG-IFN-α2a for the prevention and treatment of HCC.     

The Effect of Attachment Site Mutations on Strand Exchange in Bacteriophage λ Site-Specific Recombination

Recombination of phage λ attachment sites occurs by sequential exchange of the DNA strands at two specific locations. The first exchange produces a Holliday structure, and the second resolves it to recombinant products. Heterology for base substitution mutations in the region between the two strand exchange points (the overlap region) reduces recombination; some mutations inhibit the accumulation of Holliday structures, others inhibit their resolution to recombinant products. To see if heterology also alters the location of the strand exchange points, we determined the segregation pattern of three single and one multiple base pair substitution mutations of the overlap region in crosses with wild type sites. The mutations are known to differ in the severity of their recombination defect and in the stage of strand exchange they affect. The three single mutations behaved similarly: each segregated into both products of recombination,, and the two products of a single crossover were frequently nonreciprocal in the overlap region. In contrast, the multiple mutation preferentially segregated into one of the two recombinant products, and the two products of a single crossover appeared to be fully reciprocal. The simplest explanation of the segregation pattern of the single mutations is that strand exchanges occur at the normal locations to produce recombinants with mismatched base pairs that are frequently repaired. The segregation pattern of the multiple mutation is consistent with the view that both strand exchanges usually occur to one side of the mutant site. We suggest that the segregation pattern of a particular mutation is determined by which stage of strand exchange it inhibits and by the severity of the inhibition.     

Phosphoglycerylethanolamine Posttranslational Modification of Plant Eukaryotic Elongation Factor 1α

Eukaryotic elongation factor 1α (eEF-1A) is a multifunctional protein. There are three known posttranslational modifications of eEF-1A that could potentially affect its function. Except for phosphorylation, the other posttranslational modifications have not been demonstrated in plants. Using matrix-assisted laser desorption/ionization-mass spectrometry and peptide mass mapping, we show that carrot (Daucus carota L.) eEF-1A contains a phosphoglycerylethanolamine (PGE) posttranslational modification. eEF-1A was the only protein labeled with [¹⁴C]ethanolamine in carrot cells and was the predominant ethanolamine-labeled protein in Arabidopsis seedlings and tobacco (Nicotiana tabacum L.) cell cultures. In vivo-labeling studies using [³H]glycerol, [³²P]Pi, [¹⁴C]myristic acid, and [¹⁴C]linoleic acid indicated that the entire phospholipid phosphatidylethanolamine is covalently attached to the protein. The PGE lipid modification did not affect the partitioning of eEF-1A in Triton X-114 or its actin-binding activity in in vitro assays. Our in vitro data indicate that this newly characterized posttranslational modification alone does not affect the function of eEF-1A. Therefore, the PGE lipid modification may work in combination with other posttranslational modifications to affect the distribution and the function of eEF-1A within the cell.     

Synthesis and In vitro Biological Activity of Cyclic Lipophilic χ-Conotoxin MrIA Analogues

The 13-residue peptide, χ-conotoxin MrIA extracted from the venom of Conus marmoreus, is a potent and selective inhibitor of the human noradrenaline transporter (NET). With the aim of improving its biophysical properties, chemical modifications were performed including the attachment of a lipophilic amino acid at the N-terminus and cyclisation of the peptide backbone with functionality introduced into the linker. All χ-conotoxin MrIA analogues were assembled on solid phase by highly optimised Boc chemistry and N- to C-cyclic analogues accessed by cysteine-mediated intramolecular native chemical ligation. In vitro biological activity at the human NET was evaluated by functional assays. All analogues inhibited the uptake of [³H]noradrenaline with comparable potencies to that of the native peptide, with one of the analogues, the linear N-terminal aminotetradecanoyl MrIA showing a 3-fold increase in potency (p < 0.05).