Design of HR1 and HR2 synthetic peptide analogs: Characterization of their antiviral activities and their capacities to induce neutralizing antibodies

International audienc

Synthesis and in vitro, ex-vivo and in vivo activity of hybrid compounds linking a potent ROS and RNS scavenger activity with diverse substrates addressed to pass across the blood-brain barrier

The synthesis of a small library of CR-6 (a potent ROS and RNS scavenger agent) derivatives bearing covalent linkage with different endogen nutrients that have specific transport through the blood-brain barrier (BBB) is reported

Trimeric heptad repeat synthetic peptides HR1 and HR2 efficiently inhibit HIV-1 entry

International audienceThe trimeric heptad repeat domains HR1 and HR2 of the human immunodeficiency virus 1 (HIV-1) gp41 play a key role in HIV-1-entry by membrane fusion. To develop efficient inhibitors against this step, the corresponding trimeric-N36 and C34 peptides were designed and synthesized. Analysis by circular dichroism of monomeric and trimeric N36 and C34 peptides showed their capacities to adopt α-helical structures and to establish physical interactions. At the virological level, while trimeric-C34 conserves the same high anti-fusion activity as monomeric-C34, trimerization of N36-peptide induced a significant increase, reaching 500-times higher in anti-fusion activity, against R5-tropic virus-mediated fusion. This result was associated with increased stability of the N36 trimer peptide with respect to the monomeric form, as demonstrated by the comparative kinetics of their antiviral activities during 6-day incubation in a physiological medium. Collectively, our findings demonstrate that while the trimerization of C34 peptide had no beneficial effect on its stability and antiviral activity, the trimerization of N36 peptide strengthened both stability and antiviral activity. This approach, promotes trimers as new promising HIV-1 inhibitors and point to future development aimed toward innovative peptide fusion inhibitors, microbicides or as immunogens

Applying the retro-enantio approach to obtain a peptide capable of overcoming the blood-brain barrier

The blood-brain barrier (BBB) is a formidable physical and enzymatic barrier that tightly controls the passage of molecules from the blood to the brain. In fact, less than 2% of all potential neurotherapeutics are able to cross it. Here, by applying the retro-enantio approach to a peptide that targets the transferrin receptor, a full protease-resistant peptide with the capacity to act as a BBB shuttle was obtained and thus enabled the transport of a variety of cargos into the central nervous system

Differential neuroprotective effects of 5'-deoxy-5'-methylthioadenosine

Background 5′-deoxy-5′-methylthioadenosine (MTA) is an endogenous compound produced through the metabolism of polyamines. The therapeutic potential of MTA has been assayed mainly in liver diseases and, more recently, in animal models of multiple sclerosis. The aim of this study was to determine the neuroprotective effect of this molecule in vitro and to assess whether MTA can cross the blood brain barrier (BBB) in order to also analyze its potential neuroprotective efficacy in vivo. Methods Neuroprotection was assessed in vitro using models of excitotoxicity in primary neurons, mixed astrocyte-neuron and primary oligodendrocyte cultures. The capacity of MTA to cross the BBB was measured in an artificial membrane assay and using an in vitro cell model. Finally, in vivo tests were performed in models of hypoxic brain damage, Parkinson's disease and epilepsy. Results MTA displays a wide array of neuroprotective activities against different insults in vitro. While the data from the two complementary approaches adopted indicate that MTA is likely to cross the BBB, the in vivo data showed that MTA may provide therapeutic benefits in specific circumstances. Whereas MTA reduced the neuronal cell death in pilocarpine-induced status epilepticus and the size of the lesion in global but not focal ischemic brain damage, it was ineffective in preserving dopaminergic neurons of the substantia nigra in the 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyr​idine(MPTP)-mice model. However, in this model of Parkinson's disease the combined administration of MTA and an A2A adenosine receptor antagonist did produce significant neuroprotection in this brain region. Conclusion MTA may potentially offer therapeutic neuroprotection

Differential neuroprotective effects of 5'-Deoxy-5'-Methylthioadenosine

Background: 59-deoxy-59-methylthioadenosine (MTA) is an endogenous compound produced through the metabolism of polyamines. The therapeutic potential of MTA has been assayed mainly in liver diseases and, more recently, in animal models of multiple sclerosis. The aim of this study was to determine the neuroprotective effect of this molecule in vitro and to assess whether MTA can cross the blood brain barrier (BBB) in order to also analyze its potential neuroprotective efficacy in vivo. Methods: Neuroprotection was assessed in vitro using models of excitotoxicity in primary neurons, mixed astrocyte-neuron and primary oligodendrocyte cultures. The capacity of MTA to cross the BBB was measured in an artificial membrane assay and using an in vitro cell model. Finally, in vivo tests were performed in models of hypoxic brain damage, Parkinson’s disease and epilepsy. Results: MTA displays a wide array of neuroprotective activities against different insults in vitro. While the data from the two complementary approaches adopted indicate that MTA is likely to cross the BBB, the in vivo data showed that MTA may provide therapeutic benefits in specific circumstances. Whereas MTA reduced the neuronal cell death in pilocarpine-induced status epilepticus and the size of the lesion in global but not focal ischemic brain damage, it was ineffective in preserving dopaminergic neurons of the substantia nigra in the 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP)-mice model. However, in this model of Parkinson’s disease the combined administration of MTA and an A2A adenosine receptor antagonist did produce significant neuroprotection in this brain region. Conclusion: MTA may potentially offer therapeutic neuroprotection

MTA effects in chronic pilocarpine-induced status epilepticus (SE).

<p>a–f: Representative images of Neu N immunoreactivity in the hippocampus are shown 3 days after sham treatment (a) or pilocarpine-induced SE (b, c), or 30 days after SE (d–f). MTA (30 mg/kg) was administered pre-SE (d) or post-SE (c,f) induction. Cell loss is already apparent by 3 days (arrows in b) and is marked by 30 days (e) after SE, but it appears attenuated in MTA-treated animals at both timepoints (c,d,f). g–h) Bar plots show quantification of NeuN-positive cells in CA3(g) or CA1(h) 30 days after SE in animals pre-treated with MTA. The data represent the mean ± SEM. *p<0.05; **p<0.001; ANOVA with Tukey HSD post –hoc test.</p

Effect of MTA under OGD and AMPA excitotoxicity.

<p>Panels a and b: the effect of APV (100 µM) or MTA in OGD conditions in rat mixed cultures of neurons and astrocytes. Cell death was expressed as the LDH activity at the beginning of any treatment: *<i>p</i><0.05 compared to IAA-treated cells; # <i>p</i><0.05 compared to control; ** <i>p</i><0.01 compared to IAA-treated cells; ## <i>p</i><0.01 compared to control. <b>c</b>) primary oligodendrocytes derived from rat optic nerve subjected to AMPA excitotoxicity (10 µM and 100 µM) in which cell death was measured with calcein-AM, as indicated in Methods. *p<0.05 compared with cells treated with AMPA (Unpaired t-test). Values represent the average ± SEM and were obtained from at least three independent experiments performed in duplicates.</p

Effect of MTA on brain ischemia.

<p>(a) Representative TTC stained sections of vehicle and MTA treated animals (30 mg/kg/twice daily, i.p.) 3 days after the induction of transient focal ischemia. Histogram (right) showing the infarct volume calculated from TTC stained slices in vehicle- and MTA-treated rats (n = 5 in each group). b) Representative microphotographs of Fluoro Jade C staining after rat transient forebrain ischemia (n = 5 in the vehicle group; n = 6 in the MTA-treated group). MTA (30 mg/kg) was administered 30 min after triggering ischemia. Quantification of Fluoro Jade positive cells per mm length of CA1 pyramidal layer (right). The data represents the mean ± SEM: **p<0.01 compared to the vehicle (Student t-test). Scale bar 100 µm.</p

Effect of MTA and A_2AR antagonists in an acute mouse model of PD.

<p>The effect of MTA (30 mg/kg), MSX-3 (9 mg/kg) or both in combination on the survival of dopaminergic neurons (TH⁺ cells) within the <i>substantia nigra</i> of the brain of mice treated with MPTP. a) Representative images of the neurodegeneration of dopaminergic cells in the different groups. b) Stereological counts of TH⁺ neurons in control and drug-treated animals (n = 6 per group). The data represent the mean±SEM: *<i>p</i><0.05 comparing with the MPTP group; # <i>p</i><0.05 comparing with the control group (One-way ANOVA, LSD test as a post-hoc). Scale bar: 50 µm.</p