Natural human Bet v 1-specific IgG antibodies recognize non-conformational epitopes whereas IgE reacts with conformational epitopes

BACKGROUND

The nature of epitopes on Bet v 1 recognized by natural IgG antibodies of birch pollen allergic patients and birch pollen-exposed but non-sensitized subjects has not been studied in detail.

OBJECTIVE

To investigate IgE and IgG recognition of Bet v 1 and to study the effects of natural Bet v 1-specific IgG antibodies on IgE recognition of Bet v 1 and Bet v 1-induced basophil activation.

METHODS

Sera from birch pollen allergic patients (BPA, n = 76), allergic patients without birch pollen allergy (NBPA, n = 40) and non-allergic individuals (NA, n = 48) were tested for IgE, IgG as well as IgG1 and IgG4 reactivity to folded recombinant Bet v 1, two unfolded recombinant Bet v 1 fragments comprising the N-terminal (F1) and C-terminal half of Bet v 1 (F2) and unfolded peptides spanning the corresponding sequences of Bet v 1 and the apple allergen Mal d 1 by ELISA or micro-array analysis. The ability of Bet v 1-specific serum antibodies from non-allergic subjects to inhibit allergic patients IgE or IgG binding to rBet v 1 or to unfolded Bet v 1-derivatives was assessed by competition ELISAs. Furthermore, the ability of serum antibodies from allergic and non-allergic subjects to modulate Bet v 1-induced basophil activation was investigated using rat basophilic leukaemia cells expressing the human FcεRI which had been loaded with IgE from BPA patients.

RESULTS

IgE antibodies from BPA patients react almost exclusively with conformational epitopes whereas IgG, IgG1 and IgG4 antibodies from BPA, NBPA and NA subjects recognize mainly unfolded and sequential epitopes. IgG competition studies show that IgG specific for unfolded/sequential Bet v 1 epitopes is not inhibited by folded Bet v 1 and hence the latter seem to represent cryptic epitopes. IgG reactivity to Bet v 1 peptides did not correlate with IgG reactivity to the corresponding Mal d 1 peptides and therefore does not seem to be a result of primary sensitization to PR10 allergen-containing food. Natural Bet v 1-specific IgG antibodies inhibited IgE binding to Bet v 1 only poorly and could even enhance Bet v 1-specific basophil activation.

CONCLUSION

IgE and IgG antibodies from BPA patients and birch pollen-exposed non-sensitized subjects recognize different epitopes. These findings explain why natural allergen-specific IgG do not protect against allergic symptoms and suggest that allergen-specific IgE and IgG have different clonal origin.

The Value of Stress-Gated Blood Pool SPECT in Predicting Early Postoperative Period Complications in Ischemic Cardiomyopathy Patients: Focus on Mechanical Dyssynchrony

(1) Objective: The objective of this study was to assess the prognostic value of stress-gated blood pool SPECT (GBPS) estimates in patients with ischemic cardiomyopathy (ICM) in the early postoperative period. (2) Methods: A total of 57 patients (age 59.7 ± 6.6, 47 men) with ICM and LV ejection fraction (30 [27.5; 35]%) were enrolled in the study. Before surgical treatment, all patients underwent GBPS (rest-stress, dobutamine doses of 5/10/15 µg/kg/min). Stress-induced changes in left ventricular (LV) ejection fraction, peak ejection rate, volumes, and mechanical dyssynchrony (phase histogram standard deviation, phase entropy (PE), and phase histogram bandwidth) were estimated. Two-dimensional transthoracic echocardiography was performed baseline. Serum levels of NT-proBNP were analyzed with enzyme-linked immunoassay. (3) Results: After surgical treatment, patients were divided into two groups, one, with death, the need for an intra-aortic balloon pump (IABP) or/and inotropic support with a stay in the intensive care unit for more than two days and two, without complications in the early postoperative period (EPOP). Complicated EPOP (CEPOP) was observed in 17 (30%) patients (death-2, IABP-4, extra inotropic support in intensive care unit-11), and 40 patients had no complications (NCEPOP). GBPS showed differences in LV EDV (mL) (321 [268; 358] vs. 268 [242; 313], p = 0.02), LV ESV (mL) (242 [201; 282] vs. 196 [170; 230], p = 0.005), and stress-induced changes in PE (1 (-2; 3) vs. -2 (-4; 0), p = 0.02). Aortic cross-clamp time and stress-induced changes in PE between rest and dobutamine dose of 10 µg/kg/min were the only independent predictors of CEPOP. An increase in LV entropy ≥ 1 on the dobutamine dose of 10µg/kg/min in comparison to rest investigation showed AUC = 0.853 (sensitivity = 62%, specificity = 90%, PPV = 71%; NPV = 85%; p < 0.0001). Conclusion: Stress-induced changes in PE obtained during low-dose dobutamine GBPS are associated with a complicated course of the early postoperative period after surgical treatment for ICM.

Treatment of COVID-19 patients with a SARS-CoV-2-specific siRNA-peptide dendrimer formulation

BACKGROUND

Severe acute respiratory syndrome corona virus (SARS-CoV-2) infection frequently causes severe and prolonged disease but only few specific treatments are available. We aimed to investigate safety and efficacy of a SARS-CoV-2-specific siRNA-peptide dendrimer formulation MIR 19® (siR-7-EM/KK-46) targeting a conserved sequence in known SARS-CoV-2 variants for treatment of COVID-19.

METHODS

We conducted an open-label, randomized, controlled multicenter phase II trial (NCT05184127) evaluating safety and efficacy of inhaled siR-7-EM/KK-46 (3.7 mg and 11.1 mg/day: low and high dose, respectively) in comparison with standard etiotropic drug treatment (control group) in patients hospitalized with moderate COVID-19 (N = 52 for each group). The primary endpoint was the time to clinical improvement according to predefined criteria within 14 days of randomization.

RESULTS

Patients from the low-dose group achieved the primary endpoint defined by simultaneous achievement of relief of fever, normalization of respiratory rate, reduction of coughing, and oxygen saturation of >95% for 48 h significantly earlier (median 6 days; 95% confidence interval [CI]: 5-7, HR 1.75, p = .0005) than patients from the control group (8 days; 95% CI: 7-10). No significant clinical efficacy was observed for the high-dose group. Adverse events were reported in 26 (50.00%), 25 (48.08%), and 28 (53.85%) patients from the low-, high-dose and control group, respectively. None of them were associated with siR-7-EM/KK-46.

CONCLUSIONS

siR-7-EM/KK-46, a SARS-CoV-2-specific siRNA-peptide dendrimer formulation is safe, well tolerated and significantly reduces time to clinical improvement in patients hospitalized with moderate COVID-19 compared to standard therapy in a randomized controlled trial.

Silencing of SARS-CoV-2 with modified siRNA-peptide dendrimer formulation

Background

First vaccines for prevention of Coronavirus disease 2019 (COVID‐19) are becoming available but there is a huge and unmet need for specific forms of treatment. In this study we aimed to evaluate the anti‐SARS‐CoV‐2 effect of siRNA both in vitro and in vivo.

Methods

To identify the most effective molecule out of a panel of 15 in silico designed siRNAs, an in vitro screening system based on vectors expressing SARS‐CoV‐2 genes fused with the firefly luciferase reporter gene and SARS‐CoV‐2‐infected cells was used. The most potent siRNA, siR‐7, was modified by Locked nucleic acids (LNAs) to obtain siR‐7‐EM with increased stability and was formulated with the peptide dendrimer KK‐46 for enhancing cellular uptake to allow topical application by inhalation of the final formulation – siR‐7‐EM/KK‐46. Using the Syrian Hamster model for SARS‐CoV‐2 infection the antiviral capacity of siR‐7‐EM/KK‐46 complex was evaluated.

Results

We identified the siRNA, siR‐7, targeting SARS‐CoV‐2 RNA‐dependent RNA polymerase (RdRp) as the most efficient siRNA inhibiting viral replication in vitro. Moreover, we showed that LNA‐modification and complexation with the designed peptide dendrimer enhanced the antiviral capacity of siR‐7 in vitro. We demonstrated significant reduction of virus titer and lung inflammation in animals exposed to inhalation of siR‐7‐EM/KK‐46 in vivo.

Conclusions

Thus, we developed a therapeutic strategy for COVID‐19 based on inhalation of a modified siRNA‐peptide dendrimer formulation. The developed medication is intended for inhalation treatment of COVID‐19 patients.

The role of stress-induced dyssynchrony obtained from nuclear modalities in evaluation of high-risk patients after surgical treatment of ischemic cardiomyopathy

Funding Acknowledgements

Type of funding sources: None.

Background

Mechanical dyssynchrony (MD) is a well-known parameter witch has prognostic value [1]. Stress tests can be used to unmask MD. However, stress-induced changes in left ventricle (LV) MD by data of nuclear imaging modalities are not well-understood, especially its predictive value [2].

Purpose. To assess the role of stress-induced changes of LV MD obtained by nuclear modalities in evaluating high-risk patients after surgical treatment of ischemic cardiomyopathy (ICM).

Methods. Sixty-nine patients with ICM were enrolled. Before surgical treatment all patients underwent gated myocardial perfusion imaging (gMPI) (Tc99m-MIBI; 2 days stress-rest protocol, adenosine 140mkg/kg/min) and gated blood pool SPECT (gBPS) (rest – stress, dobutamine doses of 5/10/15 µg/kg/min). After surgical treatment patients were divided into 2 groups: with (n = 21) and without (n = 48) complicated course of early postoperative period (death, intra-aortic balloon pump, extra inotropic support). The following parameters were estimated: summed stress score (SSS), summed rest score (SRS), summed different score (SDS); phase mean, phase standard deviation (PSD) and histogram bandwidth (HBW) (% from cycle for MPI; degrees for gBPS); phase entropy (%, only by gBPS). Stress-induced changes (Δ) were calculated for MPI indices as [stress value-rest value], for gBPS indices as [value on each dobutamine dose-rest value]. For gBPS the maximum changes of MD were calculated as well.

Results. Rest gBPS MD correlated with SRS better than rest gMPI (gMPI: PSD r = 0.31, p = 0.005; HBW r = 0.28, p = 0.008; gBPS: PSD r = 0.47, p &lt; 0.001; HBW r = 0.36, p = 0.006; entropy r = 0.39, p = 0.003). Stress gBPS MD correlated better with post stress gMPI MD at the dobutamine dose of 5µg/kg/min. An following increase of the dobutamine dose led to a decrease in the r-value, but it remained significant for all indices (tab.1). Stress-induced MD changes didn’t correlate between gMPI and gBPS. Mann-Whitney test showed significant differences in SDS (p = 0.02) between the groups. Both methods didn’t show any differences at rest study. Stress-induced changes of MD showed differences between groups in only ΔEntropy rest-10µg/kg/min (p = 0.02) and maximum ΔEntropy (p = 0.01) by gBPS, as well as Δphase mean (p = 0.03) by gMPI. Logistic regression analysis showed that only maximum ΔEntropy has prognostic value in prediction of the course of early postoperative period (OR 1.2 95%CI 1.04; 1.37). ROC-analysis showed sensitivity of 80% and specificity of 55% with AUC of 0.7 for cut-off value &gt;0.

Conclusion. LVMD obtained from gBPS is associated with SRS better than those obtained from gMPI. Dyssynchrony indices obtained from gMPI with adenosine stress-test have a week to moderate correlation with those obtained from dobutamine gBPS, and correlation decrease with increasing of dobutamine dose. Only maximum ΔEntropy obtained from dobutamine gBPS is associated with the adverse course of early postoperative period in patients with ICM.

The detection of multivessel coronary artery disease: the value of quantitative myocardial blood flow and coronary flow reserve assessment

Background/Introduction

The recent Cadmium-Zinc-Telluride (CZT) camera for MPS allows evaluating absolute MBF and CFR, possibly increasing the accuracy in detecting of multivessel CAD.

Purpose

To evaluate the accuracy of myocardial blood flow (MBF) and coronary flow reserve (CFR) quantitation performed by myocardial perfusion scintigraphy (MPS) for the detection of multivessel coronary artery disease (CAD).

Methods

Fifty-two patients with suspected or known CAD were enrolled in the study. All patients underwent CZT MPS, with the evaluation of MBF and CFR, followed by invasive coronary angiography. According to MPS and coronary angiography results, patients were divided into three groups. 1) non-obstructive CAD and normal MPS scan (control group) (n=7), 2) one vessel disease (1VD) (n=16), with significant coronary stenosis (≥70%) in one major epicardial coronary artery, 3) multivessel disease (MVD) group (n=29), with two or more major epicardial coronary arteries with (≥70%) stenoses or with ≥50% LMA stenosis.

Results

Absolute MBF and CFR were significantly reduced in patients with MVD as compared to those with 1VD [0.93 (IQR 0.76; 1.39) vs 1.94 (1.37; 2.21) ml/min/g, p=0.00012] and [1.4 (IQR 1.02; 1.85) vs 2.3 (1.8; 2.67), p=0.0004], respectively. The Syntax score correlated with global stress MBF (ρ=−0.64; p&lt;0.0001) and CFR (ρ=−0.53; p=0.0003). ROC analysis showed higher sensitivity and specificity for stress MBF (85.2% and 81%), and CFR (88.9% and 80%) compared with semiquantitative MPS stress evaluation (69% and 69%). Multivariate regression analysis showed that only stress MBF [OR (95% CI) 0.59 (0.42–0.82); p&lt;0.0003] was an independent predictor of MVD.

Conclusion

The use of absolute myocardial blood flow analysis with the CZT camera may identify high risk patients, such as those with multivessel disease. This approach could be used in clinical practice, increasing the accuracy in the evaluation of patients with known or suspected coronary artery disease.

Funding Acknowledgement

Type of funding source: None

Anti-inflammatory effect of fullerene C60 in a mice model of atopic dermatitis

Background

Water-soluble form of fullerene C₆₀ is a promising tool for the control of ROS-dependent inflammation including allergic diseases. Anti-inflammatory effects of C₆₀ (nC₆₀) aqueous dispersion were evaluated in the mouse models of atopic dermatitis using subcutaneous (SC) and epicutaneous (EC) applications during 50 days period. A highly stable nC₆₀ was prepared by exhaustive dialysis of water-organic C₆₀ solution against water, where the size and ζ-potential of fullerene nanoparticles are about 100 nm and −30 mV, respectively.

Results

To induce skin inflammation, female BALB/c mice were EC sensitized with ovalbumin three times during one-weekly exposures. The nC₆₀ solution was administrated in mice subcutaneously (SC) (0.1 mg/kg) and epicutaneously (EC) (1 mg/kg). Significant suppression of IgE and Th2 cytokines production and a concomitant rise in concentrations of Th1 cytokines were observed in nC₆₀-treated groups. In addition, a significant increase in the levels of Foxp3⁺ and filaggrin mRNA expression was observed at EC application. Histological examination of skin samples indicated that therapeutic effect was achieved by both EC and SC treatment, but it was more effective with EC. Pronounced reduction of the eosinophil and leukocyte infiltration in treated skin samples was observed.

Conclusions

We suppose that nC60 treatment shifts immune response from Th2 to Th1 and restores to some extent the function of the skin barrier. This approach can be a good alternative to the treatment of allergic and other inflammatory diseases.

Allergen-Specific Immunotherapy with Monomeric Allergoid in a Mouse Model of Atopic Dermatitis

Atopic dermatitis (AD) is a widespread and difficult to treat allergic skin disease and is a tough challenge for healthcare. In this study, we investigated whether allergen-specific immunotherapy (ASIT) with a monomeric allergoid obtained by succinylation of ovalbumin (sOVA) is effective in a mouse model of atopic dermatitis. An experimental model of AD was reproduced by epicutaneous sensitization with ovalbumin (OVA). ASIT was performed with subcutaneous (SC) administration of increasing doses of OVA or sOVA. The levels of anti-OVA antibodies, as well as cytokines, were detected by ELISA. Skin samples from patch areas were taken for histologic examination. ASIT with either OVA or sOVA resulted in a reduction of both the anti-OVA IgE level and the IgG1/IgG2a ratio. Moreover, ASIT with sOVA increased the IFN-γ level in supernatants after splenocyte stimulation with OVA. Histologic analysis of skin samples from the sites of allergen application showed that ASIT improved the histologic picture by decreasing allergic inflammation in comparison with untreated mice. These data suggest that ASIT with a succinylated allergen represents promising approach for the treatment of AD.

Alternatively spliced Interleukin-4 protein is naturally produced in asthmatics, and elicits immune inflammation through a STAT6- and STAT3-independent mechanism (117.14)

A natural splice variant of IL-4 mRNA omits exon 2. It is unknown whether a corresponding protein, IL-4δ2, is also naturally produced. We have developed an mAb against IL-4δ2 with no cross-reactivity against IL-4. Freshly purified T cells from 8 patients with mild or moderate asthma and from 4 healthy controls were tested after up to 96 h activation with PMA/ionomycin. Levels of IL-4 and IL-4δ2 mRNAs were measured by RT-Q-PCR, and secretion of IL-4 and IL-4δ2 proteins was measured by ELISA. All cells expressed IL-4 and IL-4δ2 mRNAs; stimulation caused a 5-12 fold increase in IL-4 mRNA, and a 20-70 fold increase in IL-4δ2 mRNA at 12-24 h of activation. T cells from controls secreted IL-4 but not IL-4δ2 protein, whereas T cells from asthmatics produced both IL-4 and IL-4δ2 proteins in comparable amounts. Levels of IL-4 protein peaked at 24-48 h of activation, whereas IL-4δ2 protein peaked at 72 h. Adenoviral gene delivery of either mouse IL-4 or mouse IL-4δ2 to mouse lungs in vivo induced immune inflammation with accumulation of T and B cells in both cases. Delivery of IL-4 but not IL-4δ2 induced pulmonary eosinophilia, suggesting that IL-4 does and IL-4δ2 does not engage STAT6 signaling. Experiments in primary human T cell cultures revealed that, indeed, IL-4 but not IL-4δ2 induces phosphorylation of STAT6 or STAT3 in a time- and dose-dependent fashion. Thus, IL-4δ2 is naturally secreted as a protein; it is biologically active in vivo without engaging STAT6 or STAT3 signaling.

DNA-duplexes containing abasic sites: correlation between thermostability and acoustic wave properties

Aldehydic apurinic or apyrimidinic sites that lack a nucleobase moiety are one of the most common forms of toxic lesions in DNA. In the present study, a close structural analog of such a site, the 2-(hydroxymethyl) tetrahydrofuranyl residue, was synthesized in order to act as a model for damaged nucleic acid probes. Prepared oligodeoxyribonucleotides containing one, two or three abasic sites were hybridized to complementary sequences immobilized on a gold surface using the neutravidin-biotin interaction for study by thickness shear mode acoustic wave detector. Measurement of the complex electrical impedance of an AT-cut quartz device with immobilized biotinylated nucleotide allowed the detection of changes of series resonance frequency, Deltafs, and motional resistance, Rm, associated with duplex formation. The changes as detected by the acoustic wave method correlated well with the thermostability of DNA duplexes in solution. With respect to the latter, UV-monitored melting curves indicate that both the number of sites and their localization in the double-stranded structure influence the amount by which a 19 b.p. duplex is destabilized. The presence of 3 abasic sites completely destabilized the DNA duplex.

The detection of DNA deamination by electrocatalysis at DNA-modified electrodes

The method of electrocatalysis based on using a methylene blue (MB) as an electrochemical indicator and ferricyanide ions [Fe(CN)6]3- as an electron acceptor was applied in screening DNA for lesions caused by deamination of nucleobases. The damaged DNA was modeled by short 18-mer oligonucleotides containing the different number of mismatched target bases (uracil instead of cytosine residues). The hybridization capacity of these oligomers with complementary probes (immobilized on gold electrodes or free) was investigated by both electrochemical methods and UV spectroscopy. We have shown that the amplitude of the reduction signal corresponding to ferricyanide ions considerably increases in the presence of MB. This electrocatalytic effect allowed us to detect the changes in electrochemical properties of DNA caused by dU.dG mismatches. Using differential pulse voltammetry and cyclic voltammetry, we showed that the electron transport from the electrode through the double-stranded DNA to MB and then to ferricyanide ions is suppressed by the mismatches in duplex structure. According to UV-monitored melting data, single or multiple wobble dU.dG base pairs destabilize 18-mer DNA duplex by 9-27 degrees C.

Chemical composition of the lipophylic extract from the tunicate Botryllus schlosseri

Eighteen sterols were identified in Botryllus schlosseri, stanols being the main sterols. The sterol composition is in agreement with our recent paper on taxonomic separation of tunicates into three groups. Again we found in invertebrates of the Black Sea sterols with a (22Z)-double bond. This confirms the presence of such sterols in nature. The composition of the phospholipids appeared to be complex, and twelve groups of them were identified in Botryllus schlosseri. The main representatives of phospholipids appeared to be phosphatidylcholine and phosphatidylethanolamine. Only four volatile compounds were identified, which is unusual for marine invertebrates.

In vivo testing of Enterogenin for a mutagenic activity of bone marrow hemopoietic tissue of mice

The purpose of the present study was to test Enterogenin for genotoxicity. The micronuclearic test of Schmid W. was used. Enterogenin was introduced intraperitoneally, once and/or twice in two doses on male and female mice of the BDF 1 hybrid line. The positive controls were injected with clastogenic agent. Bone marrow smear preparations were made, determining the ratio between the normochromic erythrocytes (NCE) and polychromic erythrocytes (PCE), and the number of micronuclearic erythrocytes (MNE). Enterogenin has no genotoxic effect on the hemopoietic tissue of bone marrow of mice the ratio NCE/PCE being within the reference values. The preparation showed no clastogenic effect (p > 0.05), compared to the controls, as the number of PCE with micronuclei did not change 24, 48 and 72 hours after treatment with the two studied doses.

Expression of a functional anaphylatoxin C3a receptor by astrocytes

Human astrocyte cell lines reportedly contain a specific receptor for the complement anaphylatoxin C3a based on ligand-binding studies, functional responses, and RNA analysis by RT-PCR. Uptake of 125I-C3a by astrocytes was specific and reversible. Scatchard analysis indicated the presence of two classes of binding sites. High-affinity binding sites were abundantly expressed (20,000-80,000 sites per cell) with an estimated K(D) of 1-2 nM. Low-affinity binding sites with a K(D) of 209 nM were largely expressed (n > or = 4 x 10(6) sites per cell) and probably did not reflect a receptor-mediated binding, but rather an ionic interaction between C3a and the membrane. Analysis of astrocyte mRNA by RT-PCR with three different sets of primers covering 60% of the C3a receptor (C3aR) mRNA sequence indicated that glial C3aR was identical to the leukocytic one. Western blot analysis using a specific anti-C3aR evidenced a C3aR with a molecular mass of 60,000 Da. C3a and a superagonist peptide, E7, induced a transient increase of intracellular [Ca2+] in primary culture of astrocytes. Treatment of the ligands by carboxypeptidase B to eliminate the C-terminus Arg considerably decreased the [Ca2+] response. Moreover, flow cytometry experiments demonstrated the expression of C3aR on normal rat astrocyte membrane. This report brings new insight for the role of the complement system in the brain inflammation response.

Complement peptide C3a inhibits IgE-mediated triggering of rat mucosal mast cells

The relationship between mast cells' secretory response to stimulation via their type 1 Fc epsilon receptors (Fc epsilon RI) and that provided by the C3a fragment of the complement system was investigated in the rat mucosal-type mast cell line RBL-2H3. These cells are known to be unresponsive to the so-called 'peptidergic' stimulus provided by cationic agents, such as anaphylatoxins, neuropeptides or polyamines. We now observed that C3a effectively inhibits the Fc epsilon RI clustering induced secretion of RBL-2H3 cells. This inhibition is dose-dependent and takes place at a C3a concentration range of 0.4-12.5 nM, i.e. at least three orders of magnitude lower than those where this anaphylatoxin exerts its secretory stimulus to 'serosal' mast cells. In order to identify where C3a interferes in the Fc epsilon RI coupling cascade, we have studied its effect on the cells' protein phosphorylation pattern, hydrolysis of phosphatidyl inositides, transient rise in free cytosolic Ca2+ ion concentration and Ca2+ uptake. All these processes were found to be inhibited by a similar C3a concentration range.

Activation of the endothelium by IL-1 alpha and glucocorticoids results in major increase of complement C3 and factor B production and generation of C3a

Constitutive secretion of complement C3 and factor B by the endothelial cell (EC) is lowered by therapeutic concentrations of glucocorticoids such as hydrocortisone or dexamethasone, whereas regulatory protein factor H production is increased by these hormones. In contrast, the proinflammatory cytokine IL-1 alpha has a stimulatory effect on C3 and factor B secretion by the endothelium and an inhibitory effect on factor H secretion. In this study, we examined the combined effect of IL-1 alpha and glucocorticoids on C3 and factor B expression by the endothelial cell. When dexamethasone or hydrocortisone were added to IL-1 alpha, significant potentialization of IL-1 alpha-induced stimulation of C3 and factor B production was observed, occurring at various concentrations of either stimuli. Dose-response experiments indicate that, in vitro, optimal concentrations are in the range of 10(-7) to 10(-5) M for dexamethasone and 50-200 U for IL-1 alpha. In contrast, dexamethasone counteracts, in an additive way, the inhibitory effect of IL-1 alpha on regulatory complement protein factor H production by EC. Such a potentialization between glucocorticoids and IL-1 alpha was not observed for another marker of endothelial activation, IL-1 alpha-induced stimulation of coagulation tissue factor expression. The association of glucocorticoids and IL-1 alpha therefore appears to be a specific and major stimulus for the secretion of complement C3 and factor B, two acute-phase proteins, by the endothelium. As a result of the in vitro endothelium stimulation by glucocorticoids and IL-1 alpha, C3a is generated in the vicinity of the endothelial cell. This study further suggests that complement activation, with its deleterious consequences, may result from the stimulation of endothelium in situations where high levels of IL-1 alpha and endogenous glucocorticoids coexist, such as in septic shock.

Comparison of the fatty acids of the tunicate Botryllus schlosseri from the Black Sea with two associated bacterial strains

The fatty acid composition of the tunicate Botryllus schlosseri and of two bacterial strains found within the tunicate, namely Vibrio parahaemolyticus and of an associated but previously unreported gram positive cocci were studied. The polyunsaturated fatty acids 6,9,12-octadecatrienoic acid, 5,8,11,14,17-eicosapentaenoic acid, and 4,7,10,13,16,19-docosahexaenoic acid were particularly abundant in B. schlosseri and were not detected in the two bacterial strains found in the tunicate. The iso/anteiso pair, 13-methyltetradecanoic acid and 12-methyltetradecanoic acid, were the principal fatty acids in the gram positive cocci, and the 9- and 11-hexadecenoic acids were particularly abundant in V. parahaemolyticus. The diunsaturated fatty acid 9,12-octadecadienoic acid was also shown to be present in V. parahaemolyticus. The fatty acid composition of a third bacterial strain, characterized as either a Pseudomonas or an Alteromonas species, and shown to be present only in the sea water from the Black Sea and not in B. schlosseri, is also reported. This is the first investigation on fatty acids from Black Sea bacteria.

CD4-derived peptide and sulfated polysaccharides have similar mechanisms of anti-HIV activity based on electrostatic interactions with positively charged gp120 fragments

The mechanism of antiviral activity of the CD4-derived peptide 75-99 was compared with that of sulfated polysaccharides. A set of peptides representing all the high positive charge density regions of gp120 and gp41 was used to determine whether electrostatic interactions occur between these negatively charged agents and positively charged HIV envelope fragments. Synthetic peptide AZ2, amino acids 75-99 from V1 CD4, KIEDSDTYIC(Acm)-EVEDQKEEVQLLVFG, and dextran sulfate 500,000 (DS 500) were used as inhibitory agents of antibody binding in ELISA using: (1) anti-peptide rabbit antibodies; (2) sera from HIV infected persons. Peptide AZ2 and DS were both shown to block antibody binding to peptide (301-323) from the principal neutralizing domain (PND) and peptide (495-516) from the gp120 C-terminus. The blocking concns were 1-2 micrograms/ml for DS and 125-250 micrograms/ml for AZ2. The ELISA system based on rabbit anti-peptide antibodies was less sensitive than that based on positive human sera. Chemical modification of lysine epsilon-amino groups of these peptides resulted in complete failure to bind either DS or AZ2. A correlation was found between the inhibitory activities of a number of sulfated polysaccharides in a syncytium formation assay and in peptide ELISA. The mechanism of direct interactions of specific regions of gp120 with the CDR3-like region of CD4 is proposed.