Upregulation of the Renin-Angiotensin System Pathways and SARS-CoV-2 Infection: The Rationale for the Administration of Zinc-Chelating Agents in COVID-19 Patients

none1noThe article describes the rationale for the administration of zinc-chelating agents in COVID-19 patients. In a previous work I have highlighted that the binding of the SARS-CoV spike proteins to the zinc-metalloprotease ACE2 has been shown to induce ACE2 shedding by activating the zinc-metalloprotease ADAM17, which ultimately leads to systemic upregulation of ACE2 activity. Moreover, based on experimental models, it was also shown the detrimental effect of the excessive systemic activity of ACE2 through its downstream pathways, which leads to "clinical" manifestations resembling COVID-19. In this regard, strong upregulation of circulating ACE2 activity was recently reported in COVID-19 patients, thus supporting the previous hypothesis that COVID-19 may derive from upregulation of ACE2 activity. Based on this, a reasonable hypothesis of using inhibitors that curb the upregulation of both ACE2 and ADAM17 zinc-metalloprotease activities and consequent positive feedback-loops (initially triggered by SARS-CoV-2 and subsequently sustained independently on viral trigger) is proposed as therapy for COVID-19. In particular, zinc-chelating agents such as citrate and ethylenediaminetetraacetic acid (EDTA) alone or in combination are expected to act in protecting from COVID-19 at different levels thanks to their both anticoagulant properties and inhibitory activity on zinc-metalloproteases. Several arguments are presented in support of this hypothesis and based on the current knowledge of both beneficial/harmful effects and cost/effectiveness, the use of chelating agents in the prevention and therapy of COVID-19 is proposed. In this regard, clinical trials (currently absent) employing citrate/EDTA in COVID-19 are urgently needed in order to shed more light on the efficacy of zinc chelators against SARS-CoV-2 infection in vivo.openZamai, LorisZamai, Lori

Unveiling Human Non-Random Genome Editing Mechanisms Activated in Response to Chronic Environmental Changes: I. Where Might These Mechanisms Come from and What Might They Have Led To?

none1noThis article challenges the notion of the randomness of mutations in eukaryotic cells by unveiling stress-induced human non-random genome editing mechanisms. To account for the existence of such mechanisms, I have developed molecular concepts of the cell environment and cell environmental stressors and, making use of a large quantity of published data, hypothesised the origin of some crucial biological leaps along the evolutionary path of life on Earth under the pressure of natural selection, in particular, (1) virus-cell mating as a primordial form of sexual recombination and symbiosis; (2) Lamarckian CRISPR-Cas systems; (3) eukaryotic gene development; (4) antiviral activity of retrotransposon-guided mutagenic enzymes; and finally, (5) the exaptation of antiviral mutagenic mechanisms to stress-induced genome editing mechanisms directed at "hyper-transcribed" endogenous genes. Genes transcribed at their maximum rate (hyper-transcribed), yet still unable to meet new chronic environmental demands generated by "pollution", are inadequate and generate more and more intronic retrotransposon transcripts. In this scenario, RNA-guided mutagenic enzymes (e.g., Apolipoprotein B mRNA editing catalytic polypeptide-like enzymes, APOBECs), which have been shown to bind to retrotransposon RNA-repetitive sequences, would be surgically targeted by intronic retrotransposons on opened chromatin regions of the same "hyper-transcribed" genes. RNA-guided mutagenic enzymes may therefore "Lamarkianly" generate single nucleotide polymorphisms (SNP) and gene copy number variations (CNV), as well as transposon transposition and chromosomal translocations in the restricted areas of hyper-functional and inadequate genes, leaving intact the rest of the genome. CNV and SNP of hyper-transcribed genes may allow cells to surgically explore a new fitness scenario, which increases their adaptability to stressful environmental conditions. Like the mechanisms of immunoglobulin somatic hypermutation, non-random genome editing mechanisms may generate several cell mutants, and those codifying for the most environmentally adequate proteins would have a survival advantage and would therefore be Darwinianly selected. Non-random genome editing mechanisms represent tools of evolvability leading to organismal adaptation including transgenerational non-Mendelian gene transmission or to death of environmentally inadequate genomes. They are a link between environmental changes and biological novelty and plasticity, finally providing a molecular basis to reconcile gene-centred and "ecological" views of evolution.openZamai, LorisZamai, Lori

Nuclear pores in the apoptotic cell.

During apoptosis, nuclear pores undergo strong modifications, which are described here in five different apoptotic models, Conventional electron microscopy, supported by freeze-fracture analysis, showed a constant migration of nuclear pores towards the diffuse chromatin areas, In contrast, dense chromatin areas appear pore-free and are frequently surrounded by strongly dilated cistemae, A possible functional significance of this pore behaviour during apoptosis is discussed

Protein Tyrosine Phosphatase Gamma (PTPγ) is a Novel Leukocyte Marker Highly Expressed by CD34+ Precursors

Protein Tyrosine Phosphatase gamma (PTPγ) is a receptor-like transmembrane protein belonging to the family of classical protein tyrosine phosphatases. PTPγ is known to regulate haematopoietic differentiation in a murine embryonic stem cells model. We have recently demonstrated that PTPγ mRNA is expressed in monocytes, tissue-localized myeloid dendritic cells and in both myeloid and plasmacytoid dendritic cells in peripheral blood. We now developed a PTPγ specific antibody that recognizes the protein by flow cytometry. PTPγ expression was detected in monocytes and both myeloid and plasmacytoid dendritic cells, while PMN showed a low but consistent staining in contrast with previous mRNA data. B cells were found to express the phosphatase while T cells were negative. In keeping with RNA data, PTPγ was detected in monocyte-derived dendritic cells and its expression rose upon LPS stimulation. Finally, we discovered that CD34+ haematopoietic precursors express high PTPγ level that drops during in vitro expansion induced by IL-3 and SCF growth factors. We therefore propose PTPγ as a new functionally regulated leukocyte marker whose role in normal and pathological context deserve further investigation

LFA-1 antigen identifies immature stages of human NK cell differentiation

Background. Human Natural killer (NK) cells are characterized by NK cell receptors (NKRs) with inhibitory and activatory function that finely control their functional activities. In particular, they express inhibitory receptors for MHC class I molecules, named killer cell immunoglobulin (Ig)-like receptors (KIRs) and C-type lectin CD94-CD159a, and many triggering molecules like NKp30, NKp44, NKp46, (called natural cytotoxicity receptors, NCRs), NKG2D, CD161, and CD244. The majority of peripheral blood human NK cells are characterized by a phenotype with a low density expression of CD56 (CD56dim) and a high expression of CD16 (CD16bright), whereas a minority (approximately 5–10%) shows a bright expression of CD56 (CD56bright). This latter NK subset presents relatively high expression of some cytokine receptors (CD117 and CD25) and the CD94-CD159a heterodimeric inhibitory receptor. CD56bright NK cells are widely expressed in lymphoid tissues and can be generated from CD34+ cells when cultured with combinations of flt-3 ligand (FL) or stem cell factor plus IL-15 or IL-2. During their development, NK cells sequentially acquire many different antigens but there is still limited knowledge on differentiation antigens able to identify immature human NK cells and the specific sequence through which developing NK cells acquire the expression of NKR.Methods. NK cells obtained from human CD34+ hematopoietic progenitor cells after 30-day culture with FL plus IL-15, or from peripheral and umbilical cord blood samples were characterized.Results. Virtually, all CD56 NK cells differentiated in vitro expressed CD117, CD25, NCRs, NKG2D, CD161, and CD244, while only a subset expressed CD18-CD11a (LFA-1), and CD94 molecule, defining an immature CD56bright/NCRs+/NKG2D+/LFA-1-/CD94- subset. Another small subset of cells expressing CD94 but not LFA-1 integrin was also identified, suggesting that during NK differentiation LFA-1 might be upregulated later than CD94. To verify this hypothesis in vivo, we evaluated the NK cell expression of LFA-1 in both peripheral and umbilical cord blood samples. Interestingly, in these blood fluids, we have identified a lineage negative CD34-/LFA-1low/NKp46dim/NKG2Ddim/CD94- subset that resembled an immature stage of NK cells present in lymph nodes. Conclusions. Altogether, the results indicate that CD18-CD11a integrin, as well as CD11b in mice, may be a useful marker to identify immature stages of human NK cell differentiation

Role of melatonin in HT22 cells challenged with serum deprivation

In vitro serum deprivation (SD) is one model for investigating the molecular mechanisms underlying apoptosis as well as autophagy, which generally function as defense strategies upon cell injury by eliminating damaged organelles [1]. Furthermore, SD injury in vitro is widely used to mimic the ischemic environment [2]. In serum deprived conditions, cells show different parameters of apoptosis and autophagy. Melatonin (MLT), a lipophilic indole secreted by pineal and non-pineal cells, is a well-known potent free radical scavenger acting as neuroprotective molecule that prevents apoptotic cell death in several models of neurodegenerative diseases. In the present study we investigated the neuroprotective effects of MLT during SD condition on mouse hippocampal HT22 cells, considering that intracellular ROS are usually linked to autophagy and apoptosis. To explore potential effects of combining SD with melatonin we studied clonogenic survival of HT22 cells. Clonogenic assay demonstrated a significative (p< 0.01) reduction of HT22 total cell numbers challenged for 24h with SD, whereas the pre-treatment with 200nM of MLT for 24hr noticeably reduced this effect of about 30%. In HT22 starved cells the percentage of MitoTracker Red (MTR) positive cells doubled (P< 0.05) if compared to the control condition, suggesting that SD induced a remodelling of mitochondrial network. It is noteworthy that MLT pre-treatment produced a MTR positivity similar to that of controls. We next investigated whether melatonin was able to influence the autophagic pathway. Autophagy was detected by measuring the aggregation of LC3B protein coupled to green fluorescence protein (GFP). Confocal images show that SD induced an increase in the GFP-LC3 puncta, whereas the melatonin treatment reduces these aggregations. Taken together, our results suggest that MLT treatment may play protective roles against cellular modifications induced by SD treatment in HT22 cells

Lock, Stock and Barrel: Role of Renin-Angiotensin-Aldosterone System in Coronavirus Disease 2019

none16noSince the end of 2019, the medical-scientific community has been facing a terrible pandemic caused by a new airborne viral agent known as SARS-CoV2. Already in the early stages of the pandemic, following the discovery that the virus uses the ACE2 cell receptor as a molecular target to infect the cells of our body, it was hypothesized that the renin-angiotensin-aldosterone system was involved in the pathogenesis of the disease. Since then, numerous studies have been published on the subject, but the exact role of the renin-angiotensin-aldosterone system in the pathogenesis of COVID-19 is still a matter of debate. RAAS represents an important protagonist in the pathogenesis of COVID-19, providing the virus with the receptor of entry into host cells and determining its organotropism. Furthermore, following infection, the virus is able to cause an increase in plasma ACE2 activity, compromising the normal function of the RAAS. This dysfunction could contribute to the establishment of the thrombo-inflammatory state characteristic of severe forms of COVID-19. Drugs targeting RAAS represent promising therapeutic options for COVID-19 sufferers.openZanza, Christian; Tassi, Michele Fidel; Romenskaya, Tatsiana; Piccolella, Fabio; Abenavoli, Ludovico; Franceschi, Francesco; Piccioni, Andrea; Ojetti, Veronica; Saviano, Angela; Canonico, Barbara; Montanari, Mariele; Zamai, Loris; Artico, Marco; Robba, Chiara; Racca, Fabrizio; Longhitano, YaroslavaZanza, Christian; Tassi, Michele Fidel; Romenskaya, Tatsiana; Piccolella, Fabio; Abenavoli, Ludovico; Franceschi, Francesco; Piccioni, Andrea; Ojetti, Veronica; Saviano, Angela; Canonico, Barbara; Montanari, Mariele; Zamai, Loris; Artico, Marco; Robba, Chiara; Racca, Fabrizio; Longhitano, Yaroslav