Dextran sulfate from Leuconostoc mesenteroides B512F exerts potent antiviral activity against SARS-CoV-2 in vitro and in vivo

SARS–CoV–2; Dextran sulfate; NebulizationSARS–CoV–2; Sulfato de dextrano; NebulizaciónSARS–CoV–2; Sulfat de dextrano; NebulitzacióThe emergent human coronavirus SARS-CoV-2 and its resistance to current drugs makes the need for new potent treatments for COVID-19 patients strongly necessary. Dextran sulfate (DS) polysaccharides have long demonstrated antiviral activity against different enveloped viruses in vitro. However, their poor bioavailability has led to their abandonment as antiviral candidates. Here, we report for the first time the broad-spectrum antiviral activity of a DS-based extrapolymeric substance produced by the lactic acid bacterium Leuconostoc mesenteroides B512F. Time of addition assays with SARS-CoV-2 pseudoviruses in in vitro models confirm the inhibitory activity of DSs in the early stages of viral infection (viral entry). In addition, this exopolysaccharide substance also reports broad-spectrum antiviral activity against several enveloped viruses such as SARS-CoV-2, HCoV229E, HSV-1, in in vitro models and in human lung tissue. The toxicity and antiviral capacity of DS from L. mesenteroides was tested in vivo in mouse models which are susceptible to SARS-CoV-2 infection. The described DS, administered by inhalation, a new route of administration for these types of polymers, shows strong inhibition of SARS-CoV-2 infection in vivo, significantly reducing animal mortality and morbidity at non-toxic doses. Therefore, we suggest that it may be considered as a potential candidate for antiviral therapy against SARS-CoV-2.Financial support for the study was provided by the REACT-EU 2021 grant from Comunidad de Madrid to the Project COVTRAVI-19-CM, Plataformas y modelos preclínicos para el abordaje multidisciplinar en COVID-19 y en respuesta a futuras pandemias

Dextran sulfate from Leuconostoc mesenteroides B512F exerts potent antiviral activity against SARS-CoV-2 in vitro and in vivo

The emergent human coronavirus SARS-CoV-2 and its resistance to current drugs makes the need for new potent treatments for COVID-19 patients strongly necessary. Dextran sulfate (DS) polysaccharides have long demonstrated antiviral activity against different enveloped viruses in vitro. However, their poor bioavailability has led to their abandonment as antiviral candidates. Here, we report for the first time the broad-spectrum antiviral activity of a DS-based extrapolymeric substance produced by the lactic acid bacterium Leuconostoc mesenteroides B512F. Time of addition assays with SARS-CoV-2 pseudoviruses in in vitro models confirm the inhibitory activity of DSs in the early stages of viral infection (viral entry). In addition, this exopolysaccharide substance also reports broad-spectrum antiviral activity against several enveloped viruses such as SARS-CoV-2, HCoV229E, HSV-1, in in vitro models and in human lung tissue. The toxicity and antiviral capacity of DS from L. mesenteroides was tested in vivo in mouse models which are susceptible to SARS-CoV-2 infection. The described DS, administered by inhalation, a new route of administration for these types of polymers, shows strong inhibition of SARS-CoV-2 infection in vivo, significantly reducing animal mortality and morbidity at non-toxic doses. Therefore, we suggest that it may be considered as a potential candidate for antiviral therapy against SARS-CoV-2Financial support for the study was provided by the REACT-EU 2021 grant from Comunidad de Madrid to the Project COVTRAVI19-CM, Plataformas y modelos preclínicos para el abordaje multidisciplinar en COVID-19 y en respuesta a futuras pandemia

Treatment with the senolytics dasatinib/quercetin reduces SARS-CoV-2-related mortality in mice

The enormous societal impact of the ongoing COVID-19 pandemic has been particularly harsh for some social groups, such as the elderly. Recently, it has been suggested that senescent cells could play a central role in pathogenesis by exacerbating the pro-inflammatory immune response against SARS-CoV-2. Therefore, the selective clearance of senescent cells by senolytic drugs may be useful as a therapy to ameliorate the symptoms of COVID-19 in some cases. Using the established COVID-19 murine model K18-hACE2, we demonstrated that a combination of the senolytics dasatinib and quercetin (D/Q) significantly reduced SARS-CoV-2-related mortality, delayed its onset, and reduced the number of other clinical symptoms. The increase in senescent markers that we detected in the lungs in response to SARS-CoV-2 may be related to the post-COVID-19 sequelae described to date. These results place senescent cells as central targets for the treatment of COVID-19, and make D/Q a new and promising therapeutic too

Dextran sulfate from Leuconostoc mesenteroides B512F exerts potent antiviral activity against SARS-CoV-2 in vitro and in vivo

The emergent human coronavirus SARS-CoV-2 and its resistance to current drugs makes the need for new potent treatments for COVID-19 patients strongly necessary. Dextran sulfate (DS) polysaccharides have long demonstrated antiviral activity against different enveloped viruses in vitro. However, their poor bioavailability has led to their abandonment as antiviral candidates. Here, we report for the first time the broad-spectrum antiviral activity of a DS-based extrapolymeric substance produced by the lactic acid bacterium Leuconostoc mesenteroides B512F. Time of addition assays with SARS-CoV-2 pseudoviruses in in vitro models confirm the inhibitory activity of DSs in the early stages of viral infection (viral entry). In addition, this exopolysaccharide substance also reports broad-spectrum antiviral activity against several enveloped viruses such as SARS-CoV-2, HCoV229E, HSV-1, in in vitro models and in human lung tissue. The toxicity and antiviral capacity of DS from L. mesenteroides was tested in vivo in mouse models which are susceptible to SARS-CoV-2 infection. The described DS, administered by inhalation, a new route of administration for these types of polymers, shows strong inhibition of SARS-CoV-2 infection in vivo, significantly reducing animal mortality and morbidity at non-toxic doses. Therefore, we suggest that it may be considered as a potential candidate for antiviral therapy against SARS-CoV-2

Targeting senescent cells: approaches, opportunities, challenges

Cellular senescence is a hallmark of aging, whose onset is linked to a series of both cell and non-cell autonomous processes, leading to several consequences for the organism. To date, several senescence routes have been identified, which play a fundamental role in development, tumor suppression and aging, among other processes. The positive and/or negative effects of senescent cells are directly related to the time that they remain in the organism. Short-term (acute) senescent cells are associated with positive effects; once they have executed their actions, immune cells are recruited to remove them. In contrast, long-term (chronic) senescent cells are associated with disease; they secrete pro-inflammatory and pro-tumorigenic factors in a state known as senescence-associated secretory phenotype (SASP). In recent years, cellular senescence has become the center of attention for the treatment of aging-related diseases. Current therapies are focused on elimination of senescent cell functions in three main ways: i) use of senolytics; ii) inhibition of SASP; and iii) improvement of immune system functions against senescent cells (immunosurveillance). In addition, some anti-cancer therapies are based on the induction of senescence in tumor cells. However, these senescent-like cancer cells must be subsequently cleared to avoid a chronic pro-tumorigenic state. Here is a summary of different scenarios, depending on the therapy used, with a discussion of the pros and cons of each scenarioConsejo Superior de Investigaciones Científicas (CSIC

Caracterización y mecanismo de señalización intracelular del receptor de la hormona del crecimiento en linfocitos humanos

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 12-01-199

The asymmetric distribution of the constituents of the Ran system is essential for transport into and out of the nucleus

The GTPase Ran is essential for nuclear import of proteins with a classical nuclear localization signal (NLS). Ran's nucleotide‐bound state is determined by the chromatin‐bound exchange factor RCC1 generating RanGTP in the nucleus and the cytoplasmic GTPase activating protein RanGAP1 depleting RanGTP from the cytoplasm. This predicts a steep RanGTP concentration gradient across the nuclear envelope. RanGTP binding to importin‐β has previously been shown to release importin‐α from ‐β during NLS import. We show that RanGTP also induces release of the M9 signal from the second identified import receptor, transportin. The role of RanGTP distribution is further studied using three methods to collapse the RanGTP gradient. Nuclear injection of either RanGAP1, the RanGTP binding protein RanBP1 or a Ran mutant that cannot stably bind GTP. These treatments block major export and import pathways across the nuclear envelope. Different export pathways exhibit distinct sensitivities to RanGTP depletion, but all are more readily inhibited than is import of either NLS or M9 proteins, indicating that the block of export is direct rather than a secondary consequence of import inhibition. Surprisingly, nuclear export of several substrates including importin‐α and ‐β, transportin, HIV Rev and tRNA appears to require nuclear RanGTP but may not require GTP hydrolysis by Ran, suggesting that the energy for their nuclear export is supplied by another source

Poly(ADP-ribose) polymerase 1 regulates both the exonuclease and helicase activities of the Werner syndrome protein

Werner syndrome (WS) is a genetic premature aging disorder in which patients appear much older than their chronological age. The gene mutated in WS encodes a nuclear protein (WRN) which possesses 3′–5′ exonuclease and ATPase-dependent 3′–5′ helicase activities. The genomic instability associated with WS cells and the biochemical characteristics of WRN suggest that WRN plays a role in DNA metabolic pathways such as transcription, replication, recombination and repair. Recently we have identified poly(ADP-ribose) polymerase-1 (PARP-1) as a new WRN interacting protein. In this paper, we further mapped the interacting domains. We found that PARP-1 bound to the N-terminus of WRN and to the C-terminus containing the RecQ-conserved (RQC) domain. WRN bound to the N-terminus of PARP-1 containing DNA binding and BRCA1 C-terminal (BRCT) domains. We show that unmodified PARP-1 inhibited both WRN exonuclease and helicase activities, and to our knowledge is the only known WRN protein partner that inactivates both of the WRN's catalytic activities suggesting a biologically significant regulation. Moreover, this dual inhibition seems to be specific for PARP-1, as PARP-2 did not affect WRN helicase activity and only slightly inhibited WRN exonuclease activity. The differential effect of PARP-1 and PARP-2 on WRN catalytic activity was not due to differences in affinity for WRN or the DNA substrate. Finally, we demonstrate that the inhibition of WRN by PARP-1 was influenced by the poly(ADP-ribosyl)ation state of PARP-1. The biological relevance of the specific modulation of WRN catalytic activities by PARP-1 are discussed in the context of pathways in which these proteins may function together, namely in the repair of DNA strand breaks

Inhibition of paclitaxel-induced proteasome activation influences paclitaxel cytotoxicity in breast cancer cells in a sequence-dependent manner

This article is an Open Access.Although the anti-tumor effects of paclitaxel result mainly from mitotic arrest, recent evidences suggest alternative mechanisms of cytotoxicity. Cell cycle, cell death and gene expression assays were used to understand the molecular mechanisms of paclitaxel cytotoxicity in breast cancer cells. G 2/M cell cycle arrest and cell death coincided with the regulation of genes involved in cell death, cell cycle control, microtubule-based processes, oxidative stress, and ubiquitin-proteasome system. Induction of proteasome genes was also correlated with an accumulation of protein for proteasome subunits. Furthermore, a schedule-dependent regulation of paclitaxel-induced cytotoxicity was observed after combining paclitaxel and the proteasome inhibitor MG132. Proteasome inhibition after paclitaxel exposure induced the highest rate of growth inhibition and apoptosis, with no effect on mitotic arrest. These findings give support to clinical combinations of taxanes with proteasome inhibitors, outlining the importance of considering the sequence when designing such regimens. ©2007 Landes Bioscience.This work was supported by Ministerio de Educación y Ciencia, Grant Reference PTR1995-0753-OP and Ministerio de Ciencia y Tecnología SAF2001-0065 and SAF2004-08258-C02-01.Peer Reviewe