Dysfunctional purinergic signaling correlates with disease severity in COVID-19 patients.

Ectonucleotidases modulate inflammatory responses by balancing extracellular ATP and adenosine (ADO) and might be involved in COVID-19 immunopathogenesis. Here, we explored the contribution of extracellular nucleotide metabolism to COVID-19 severity in mild and severe cases of the disease. We verified that the gene expression of ectonucleotidases is reduced in the whole blood of patients with COVID-19 and is negatively correlated to levels of CRP, an inflammatory marker of disease severity. In line with these findings, COVID-19 patients present higher ATP levels in plasma and reduced levels of ADO when compared to healthy controls. Cell type-specific analysis revealed higher frequencies of CD39+ T cells in severely ill patients, while CD4+ and CD8+ expressing CD73 are reduced in this same group. The frequency of B cells CD39+CD73+ is also decreased during acute COVID-19. Interestingly, B cells from COVID-19 patients showed a reduced capacity to hydrolyze ATP into ADP and ADO. Furthermore, impaired expression of ADO receptors and a compromised activation of its signaling pathway is observed in COVID-19 patients. The presence of ADO in vitro, however, suppressed inflammatory responses triggered in patients' cells. In summary, our findings support the idea that alterations in the metabolism of extracellular purines contribute to immune dysregulation during COVID-19, possibly favoring disease severity, and suggest that ADO may be a therapeutic approach for the disease.

Quantitative Evaluation of Municipal Wastewater Disinfection by 280 nm UVC LED

UV-LED irradiation has attracted attention in water and wastewater disinfection applications. However, no studies have quantitatively investigated the impact of light intensity on the UV dosage for the same magnitude of disinfection. This study presents a powerful 280 nm UV-LED photoreactor with adjustable light intensity to disinfect municipal wastewater contaminated with E. coli, SARS-CoV-2 genetic materials and others. The disinfection performance of the 280 nm LED was also compared with 405 nm visible light LEDs, in terms of inactivating E. coli and total coliforms, as well as reducing cATP activities. The results showed that the UV dose needed per log reduction of E. coli and total coliforms, as well as cATP, could be decreased by increasing the light intensity within the investigated range (0–9640 µW/cm2). Higher energy consumption is needed for microbial disinfection using the 405 nm LED when compared to 280 nm LED. The signal of SARS-CoV-2 genetic material in wastewater and the SARS-CoV-2 spike protein in pure water decreased upon 280 nm UV irradiation. © 2023 by the authors.

COVID-19 induced liver injury from a new perspective: Mitochondria.

Liver damage is a common sequela of COVID-19 (coronavirus disease 2019), worsening the clinical outcomes. However, the underlying mechanism of COVID-induced liver injury (CiLI) is still not determined. Given the crucial role of mitochondria in hepatocyte metabolism and the emerging evidence denoting SARS-CoV-2 can damage human cell mitochondria, in this mini-review, we hypothesized that CiLI happens following hepatocytes' mitochondrial dysfunction. To this end, we evaluated the histologic, pathophysiologic, transcriptomic, and clinical features of CiLI from the mitochondria' eye view. Severe acute respiratory syndrome coronavirus 2 (SARS­CoV­2), the causative agent of COVID-19, can damage hepatocytes through direct cytopathic effects or indirectly after the profound inflammatory response. Upon entering the hepatocytes, the RNA and RNA transcripts of SARS-CoV-2 engages the mitochondria. This interaction can disrupt the mitochondrial electron transport chain. In other words, SARS-CoV-2 hijacks the hepatocytes' mitochondria to support its replication. In addition, this process can lead to an improper immune response against SARS-CoV-2. Besides, this review outlines how mitochondrial dysfunction can serve as a prelude to the COVID-associated cytokine storm. Thereafter, we indicate how the nexus between COVID-19 and mitochondria can fill the gap linking CiLI and its risk factors, including old age, male sex, and comorbidities. In conclusion, this concept stresses the importance of mitochondrial metabolism in hepatocyte damage in the context of COVID-19. It notes that boosting mitochondria biogenesis can possibly serve as a prophylactic and therapeutic approach for CiLI. Further studies can reveal this notion.

Use of ATP bioluminescence to survey the contamination of dental goggles in surgical removal of impacted mandibular third molars

The importance of protecting the eyes from infectious agents in patients' blood and saliva during dental surgery has long been known, but the global COVID-19 pandemic has made this even more important. The use of ATP bioluminescence to investigate the contamination of dental goggles during the surgical removal of impacted teeth in the present study indicates their importance for protecting the eyes from aerosols from the front, from above, and from the sides.Copyright © 2021 The Author(s)

Chansu improves the respiratory function of severe COVID-19 patients

Targeted therapeutics for SARS-CoV-2 virus caused COVID-19 are in urgent need. Chansu has been reported to have broad-spectrum antiviral effects and widely used in Southeast Asian countries. This study aims to assess the efficacy of Chansu injection in treating patients with severe COVID-19. A randomized preliminary clinical trial was conducted and eligible patients were allocated to receive general treatment plus Chansu injection or only general treatment as control for 7 days. The primary outcomes of the oxygenation index PaO2/FiO2 and ROX, secondary outcomes of white blood cell count, respiratory support step-down time (RSST), safety indicators, etc were monitored. After 7 days of treatment, the oxygenation index was improved in 95.2% patients in the treatment group compared with 68.4% in the control group. The PaO2/FiO2 and ROX indices in the treatment group (mean, 226.27+/-67.35 and 14.01+/-3.99 respectively) were significantly higher than the control group (mean, 143.23+/-51.29 and 9.64+/-5.54 respectively). The RSST was 1 day shorter in the treatment group. Multivariate regression analysis suggested that Chansu injection contributed the most to the outcome of PaO2/FiO2. No obvious adverse effects were observed. The preliminary data showed that Chansu injection had apparent efficacy in improving the respiratory function of patients with severe COVID-19.Copyright © 2021 The Authors

The Alpha-1 Subunit of the Na+/K+-ATPase (ATP1A1) Is a Host Factor Involved in the Attachment of Porcine Epidemic Diarrhea Virus.

Porcine epidemic diarrhea (PED) is an acute and severe atrophic enteritis caused by porcine epidemic diarrhea virus (PEDV) that infects pigs and makes huge economic losses to the global swine industry. Previously, researchers have believed that porcine aminopeptidase-N (pAPN) was the primary receptor for PEDV, but it has been found that PEDV can infect pAPN knockout pigs. Currently, the functional receptor for PEDV remains unspecified. In the present study, we performed virus overlay protein binding assay (VOPBA), found that ATP1A1 was the highest scoring protein in the mass spectrometry results, and confirmed that the CT structural domain of ATP1A1 interacts with PEDV S1. First, we investigated the effect of ATP1A1 on PEDV replication. Inhibition of hosts ATP1A1 protein expression using small interfering RNA (siRNAs) significantly reduced the cells susceptibility to PEDV. The ATP1A1-specific inhibitors Ouabain (a cardiac steroid) and PST2238 (a digitalis toxin derivative), which specifically bind ATP1A1, could block the ATP1A1 protein internalization and degradation, and consequently reduce the infection rate of host cells by PEDV significantly. Additionally, as expected, overexpression of ATP1A1 notably enhanced PEDV infection. Next, we observed that PEDV infection of target cells resulted in upregulation of ATP1A1 at the mRNA and protein levels. Furthermore, we found that the host protein ATP1A1 was involved in PEDV attachment and co-localized with PEDV S1 protein in the early stage of infection. In addition, pretreatment of IPEC-J2 and Vero-E6 cells with ATP1A1 mAb significantly reduced PEDV attachment. Our observations provided a perspective on identifying key factors in PEDV infection, and may provide valuable targets for PEDV infection, PEDV functional receptor, related pathogenesis, and the development of new antiviral drugs.

One-year monitoring SARS-CoV-2 RNA surface contamination in hospitals reveals no correlation with organic material and negative pressure as a limiting factor for contamination.

Understanding transmission routes of SARS-CoV-2 is crucial to establish effective interventions in healthcare institutions. Although the role of surface contamination in SARS-CoV-2 transmission has been controversial, fomites have been proposed as a contributing factor. Longitudinal studies about SARS-CoV-2 surface contamination in hospitals with different infrastructure (presence or absence of negative pressure systems) are needed to improve our understanding of their effectiveness on patient healthcare and to advance our knowledge about the viral spread. We performed a one-year longitudinal study to evaluate surface contamination with SARS-CoV-2 RNA in reference hospitals. These hospitals have to admit all COVID-19 patients from public health services that require hospitalization. Surfaces samples were molecular tested for SARS-CoV-2 RNA presence considering three factors: the dirtiness by measuring organic material, the circulation of a high transmissibility variant, and the presence or absence of negative pressure systems in hospitalized patients' rooms. Our results show that: (i) There is no correlation between the amount of organic material dirtiness and SARS-CoV-2 RNA detected on surfaces; (ii) SARS-CoV-2 high transmissible Gamma variant introduction significantly increased surface contamination; (iii) the hospital with negative pressure systems was associated with lower levels of SARS-CoV-2 surface contamination and, iv) most environmental samples recovered from contaminated surfaces were assigned as non-infectious. This study provides data gathered for one year about the surface contamination with SARS-CoV-2 RNA sampling hospital settings. Our results suggest that spatial dynamics of SARS-CoV-2 RNA contamination varies according with the type of SARS-CoV-2 genetic variant and the presence of negative pressure systems. In addition, we showed that there is no correlation between the amount of organic material dirtiness and the quantity of viral RNA detected in hospital settings. Our findings suggest that SARS CoV-2 RNA surface contamination monitoring might be useful for the understanding of SARS-CoV-2 dissemination with impact on hospital management and public health policies. This is of special relevance for the Latin-American region where ICU rooms with negative pressure are insufficient.

Rational Design and Synthesis of D-galactosyl Lysophospholipids as Selective Substrates and non-ATP-competitive Inhibitors of Phosphatidylinositol Phosphate Kinases.

Phosphatidylinositol phosphate kinases (PIPKs) produce lipid signaling molecules and have been attracting increasing attention as drug targets for cancer, neurodegenerative diseases, and viral infection. Given the potential cross-inhibition of kinases and other ATP-utilizing enzymes by ATP-competitive inhibitors, targeting the unique lipid substrate binding site represents a superior strategy for PIPK inhibition. Here, by taking advantage of the nearly identical stereochemistry between myo-inositol and D-galactose, we designed and synthesized a panel of D-galactosyl lysophospholipids, one of which was found to be a selective substrate of phosphatidylinositol 4-phosphate 5-kinase. Derivatization of this compound led to the discovery of a human PIKfyve inhibitor with an apparent IC50 of 6.2 µM, which significantly potentiated the inhibitory effect of Apilimod, an ATP-competitive PIKfyve inhibitor under clinical trials against SARS-CoV-2 infection and amyotrophic lateral sclerosis. Our results provide the proof of concept that D-galactose-based phosphoinositide mimetics can be developed into artificial substrates and new inhibitors of PIPKs.

The Role of Cluster of Differentiation 39 (CD39) and Purinergic Signaling Pathway in Viral Infections.

CD39 is a marker of immune cells such as lymphocytes and monocytes. The CD39/CD73 pathway hydrolyzes ATP into adenosine, which has a potent immunosuppressive effect. CD39 regulates the function of a variety of immunologic cells through the purinergic signaling pathways. CD39+ T cells have been implicated in viral infections, including Human Immunodeficiency Virus (HIV), Cytomegalovirus (CMV), viral hepatitis, and Corona Virus Disease 2019 (COVID-19) infections. The expression of CD39 is an indicator of lymphocyte exhaustion, which develops during chronicity. During RNA viral infections, the CD39 marker can profile the populations of CD4+ T lymphocytes into two populations, T-effector lymphocytes, and T-regulatory lymphocytes, where CD39 is predominantly expressed on the T-regulatory cells. The level of CD39 in T lymphocytes can predict the disease progression, antiviral immune responses, and the response to antiviral drugs. Besides, the percentage of CD39 and CD73 in B lymphocytes and monocytes can affect the status of viral infections. In this review, we investigate the impact of CD39 and CD39-expressing cells on viral infections and how the frequency and percentage of CD39+ immunologic cells determine disease prognosis.

Adipocytes in obesity: A perfect reservoir for SARS-CoV-2?

Research evidence suggests that adipocytes in obesity might facilitate SARS-CoV-2 replication, for it was only found in adipose tissue of individuals with overweight or obesity but not lean individuals who died from COVID-19. As lipid metabolism is key to adipocyte function, and viruses are capable of exploiting and manipulating lipid metabolism of host cells for their own benefit of infection, we hypothesize that adipocytes could not only impair host immune defense against viral infection, but also facilitate SARS-CoV-2 entry, replication and assembly as a reservoir to boost the viral infection in obesity. The latter of which could mainly be mediated by SARS-CoV-2 hijacking the abnormal lipid metabolism in the adipocytes. If these were to be confirmed, an approach to combat COVID-19 in people with obesity by taking advantage of the abnormal lipid metabolism in adipocytes might be considered, as well as modifying lipid metabolism of other host cells as a potential adjunctive treatment for COVID-19.

Energetic insufficiency of liver tissue and additional energy in digital value. (The hypothesis)

Despite the deep understanding of the importance of energy supply in the development of the vast majority of processes and phenomena in organism, there are practically no conceptual researches of energy requirements in severe diseases, traumatic injuries, stressful effects and related treatment in the medical literature. The proposed hypothesis is based on the analysis of literature data (PubMed keywords: energy deficit, stressor, metabolic stress, ATP, gluconeogenesis, oxidative phosphorylation, mitochondria, insulin secretion), reconsideration of the results of our experiments dedicated to the energetic statement of liver tissue in obstructive jaundice (OJ), ischemia and massive resection, summarization of 60 years of experience in clinical, surgical and scientific activities, which made it possible to make a number of assumptions that need further clinical and experimental verification. Various pathogens (stressors) cause the additional energy production in the body, which is the energy basis of metabolic responses that ensure the adaptation of the body's vital functions and the elimination of the pathogen by activation of innate immunity, systemic inflammatory reaction, activation of the sympathetic nervous system, etc. Additional energy is the integral strength of the response to the pathogen, that takes into consideration with the strength of the stressor and the individual strength of the body's response, which can be different for the same strength of the stressor. In fact, when stress develops, it determines its strength in digital form, i.e. in real view. The concept of this hypothesis comes from the fact that stress, which main task is to provide the energy of organism, appears when there is a certain level of energy deficiency in the body. Such level rarely appears immediately after the action of the stressor. At the beginning, pre-stress adaptive reactions usually occur, which use the energy reserve in cells in the form of ATP and glycogen, and are also the result of energy redistribution: a decrease in it in insulin-dependent tissues and an increase in insulin-independent ones, which include vital organs. This made it possible to divide metabolic responses into two groups: pre-stress and stress, and to distinguish two periods: "pre-stress" and "metabolic stress". Pre-stress reactions, in our opinion, are also aimed at preventing the development of metabolic stress, which generates energy through proteolysis and lipolysis of body tissues. Metabolic stress develops when pre-stress reactions cannot satisfy the needs of the body and a certain, expressed in numerical value, energy deficit occurs. In a certain extent the metabolic situation in the body reflects by the liver, which is a metabolic organ that performs many reactions both during normal and stressful metabolism, generates ATP energy, and takes into account the metabolic state of other organs. The level of energy deficiency of the liver tissue can be an indicator that causes the formation of metabolic stress and evaluates in a numerical value not only the energy position of the body, but also the severity of its general condition, promising opportunities, prognosis and priority treatment, which should be aimed at a comprehensive replenishment of the energy deficit. This is especially important to keep in mind at this time with severe forms of COVID-19 and low blood oxygen saturation. Under any stressful influences, the doctor must solve two problems: to deal with a specific stressor and to provide energy for this struggle and the vital activity of the patient. Functional insufficiency of the liver in its diffuse diseases can lead to impaired gluconeogenesis or oxidative phosphorylation of glucose and the formation of "unsuccessful" or "incomplete" stresses. Copyright © 2022 ANNALS OF HPB SURGERY. All rights reserved.

Modulation of ATP Production Influences Inorganic Polyphosphate Levels in Non-Athletes' Platelets at the Resting State.

Platelets produce inorganic polyphosphate (polyP) upon activation to stimulate blood coagulation. Some researchers have linked polyP metabolism to ATP production, although the metabolic linkage is yet to be elucidated. We found evidence for this possibility in our previous study on professional athletes (versus non-athletes), and proposed that the regulatory mechanism might be different for these two groups. To explore this aspect further, we investigated the effects of modulated ATP production on polyP levels. Blood samples were obtained from Japanese healthy, non-athletes in the presence of acid-citrate-dextrose. The platelets in the plasma were treated with oligomycin, rotenone, and GlutaMAX to modulate ATP production. PolyP level was quantified fluorometrically and visualized using 4',6-diamidino-2-phenylindole. Correlations between polyP and ATP or NADH were then calculated. Contrary to the hypothesis, inhibitors of ATP production increased polyP levels, whereas amino acid supplementation produced the opposite effect. In general, however, polyP levels were positively correlated with ATP levels and negatively correlated with NADH levels. Since platelets are metabolically active, they exhibit high levels of ATP turnover rate. Therefore, these findings suggest that ATP may be involved in polyP production in the resting platelets of non-athletes.

Estimating power for a multi-site treatment study leveraging natural history ABCA4- related retinopathy data

Purpose : A clinical trial of oral metformin for treatment of ABCA4 retinopathy was initiated at National Eye Institute (NEI) (ClinicalTrials.gov: NCT04545736). Power analysis was based on a single site (NEI) with high-resolution Optical Coherence Tomography (OCT) volume scans and equally spaced visits. To aid recruitment, an additional site with lower density volume scans is considered and unequally spaced visits introduced to account for missed visits due to the Coronavirus Disease 2019 pandemic. The aims were to determine the effects of adding a site that uses a mix of low- and high-resolution images and an increased number of natural history visits and spacing between visits on power. Methods : A longitudinal spline regression is proposed for the primary outcome analysis, comparing growth rate in square-root transformed ellipsoid zone band loss area on OCT between the treatment phase (current study) and pre-treatment phase (natural history study), with a knot at the baseline visit when patients initiate treatment. Data were simulated using the observed mean, variance and inter-eye correlation for baseline values (from the last available pre-treatment visit) and pre-treatment growth rates from available natural history data at NEI;expected improvement in the primary outcome due to treatment;and other salient features of the study. Low-resolution values were derived from the natural history high-resolution images at NEI. The number of pre-treatment visits and spacing between visits were varied keeping other factors constant for a fixed sample size, while accounting for the appropriate resolution values at each site. The resultant power for detecting a treatment effect was estimated based on 2000 simulated datasets. Results : The power estimated when accounting for a mix of low- and high-resolution values at the second site was the same as that with all high-resolution values at 80%. An increase from 4 to 6 pre-treatment visits increased power by 15% and increasing the spacing between visits from 6 to 12 months increased power by 6% for the study. Conclusions : Increasing the number of pre-treatment visits and spacing between visits increased power. Derivation of low-resolution values from high-resolution images may be the reason for the high correlation between the two resolutions, which may explain why including a mix of low- and high-resolution values did not decrease power.

The Use of Automated Machine Translation to Translate Figurative Language in a Clinical Setting: Analysis of a Convenience Sample of Patients Drawn From a Randomized Controlled Trial.

BACKGROUND: Patients with limited English proficiency frequently receive substandard health care. Asynchronous telepsychiatry (ATP) has been established as a clinically valid method for psychiatric assessments. The addition of automated speech recognition (ASR) and automated machine translation (AMT) technologies to asynchronous telepsychiatry may be a viable artificial intelligence (AI)-language interpretation option. OBJECTIVE: This project measures the frequency and accuracy of the translation of figurative language devices (FLDs) and patient word count per minute, in a subset of psychiatric interviews from a larger trial, as an approximation to patient speech complexity and quantity in clinical encounters that require interpretation. METHODS: A total of 6 patients were selected from the original trial, where they had undergone 2 assessments, once by an English-speaking psychiatrist through a Spanish-speaking human interpreter and once in Spanish by a trained mental health interviewer-researcher with AI interpretation. 3 (50%) of the 6 selected patients were interviewed via videoconferencing because of the COVID-19 pandemic. Interview transcripts were created by automated speech recognition with manual corrections for transcriptional accuracy and assessment for translational accuracy of FLDs. RESULTS: AI-interpreted interviews were found to have a significant increase in the use of FLDs and patient word count per minute. Both human and AI-interpreted FLDs were frequently translated inaccurately, however FLD translation may be more accurate on videoconferencing. CONCLUSIONS: AI interpretation is currently not sufficiently accurate for use in clinical settings. However, this study suggests that alternatives to human interpretation are needed to circumvent modifications to patients' speech. While AI interpretation technologies are being further developed, using videoconferencing for human interpreting may be more accurate than in-person interpreting. TRIAL REGISTRATION: ClinicalTrials.gov NCT03538860; https://clinicaltrials.gov/ct2/show/NCT03538860.

Beneficial effect of polyphenols in COVID-19 and the ectopic F1 FO -ATP synthase: Is there a link?

COVID-19 has been proposed to be an endothelial disease, as endothelial damage and oxidative stress contribute to its systemic inflammatory and thrombotic events. Polyphenols, natural antioxidant compounds appear as promising agents to prevent and treat COVID-19. Polyphenols bind and inhibit the F1 Fo -ATP synthase rotary catalysis. An early target of polyphenols may be the ectopic F1 Fo -ATP synthase expressed on the endothelial plasma membrane. Among the pleiotropic beneficial action of polyphenols in COVID-19, modulation of the ecto-F1 Fo -ATP synthase, lowering the oxidative stress produced by the electron transfer chain coupled to it, would not be negligible.

Pandemic Preparedness and Response: A Foldable Tent to Safely Remove Contaminated Dental Aerosols—Clinical Study and Patient Experience

The D-DART (Droplet and Aerosol Reducing Tent) is a foldable design that can be attached to the dental chair to prevent the spread of contaminated dental aerosols. The objective of this study was to evaluate the ability of the D-DART to reduce spread of aerosols generated during dental treatment. Thirty-two patients (sixteen per group) undergoing deep ultrasonic scaling were recruited and randomly allocated to groups D-DART or Control (no D-DART). After 20 min from the start of the treatment, the clinician’s face shield and dental chair light were swabbed and the viable microbial load was quantified (ATP bioluminescence analysis, blinded operator). Statistical analyses were performed with Tukey’s Honest Test with a level of significance pre-set at 5%. There were significant increases in ATP values obtained from the operator’s face shield and dental chair light for the Control compared with baseline (31.3 ± 8.5 and fold increase). There was no significant change in microbial load when the D-DART was used compared with baseline (1.5 ± 0.4 fold increase). The D-DART contained and prevented the spread of aerosols generated during deep scaling procedures.

Potential of ATP5MG to Treat Metabolic Syndrome-Associated Cardiovascular Diseases.

Introduction: Metabolic syndrome-associated cardiovascular disease (MetS-CVD) is a cluster of metabolism-immunity highly integrated diseases. Emerging evidence hints that mitochondrial energy metabolism may be involved in MetS-CVD development. The physiopathological role of ATP5MG, a subunit of the F0 ATPase complex, has not been fully elucidated. Methods: In this study, we selected ATP5MG to identify the immunity-mediated pathway and mine drugs targeting this pathway for treating MetS-CVD. Using big data from public databases, we dissected co-expressed RNA (coRNA), competing endogenous RNA (ceRNA), and interacting RNA (interRNA) genes for ATP5MG. Results: It was identified that ATP5MG may form ceRNA with COX5A through hsa-miR-142-5p and interplay with NDUFB8, SOD1, and MDH2 through RNA-RNA interaction under the immune pathway. We dug out 251 chemicals that may target this network and identified some of them as clinical drugs. We proposed five medicines for treating MetS-CVD. Interestingly, six drugs are being tested to treat COVID-19, which unexpectedly offers a new potential host-targeting antiviral strategy. Conclusion: Collectively, we revealed the potential significance of the ATP5MG-centered network for developing drugs to treat MetS-CVD, which offers insights into the epigenetic regulation for metabolism-immunity highly integrated diseases.

A review of the effects of ATP and hydroxychloroquine on the phase separation of the SARS-CoV-2 nucleocapsid protein.

SARS-CoV-2 is the coronavirus causing the ongoing pandemic with > 460 millions of infections and > 6 millions of deaths. SARS-CoV-2 nucleocapsid (N) is the only structural protein which plays essential roles in almost all key steps of the viral life cycle with its diverse functions depending on liquid-liquid phase separation (LLPS) driven by interacting with various nucleic acids. The 419-residue N protein is highly conserved in all variants including delta and omicron, and composed of both folded N-/C-terminal domains (NTD/CTD) as well as three long intrinsically disordered regions (IDRs). Recent results have suggested that its CTD and IDRs are also cryptic nucleic acid-binding domains. In this context, any small molecules capable of interfering in its interaction with nucleic acids are anticipated to modulate its LLPS and associated functions. Indeed, ATP, the energy currency existing at very high concentrations (2-12 mM) in all living cells but absent in viruses, modulates LLPS of N protein, and consequently appears to be evolutionarily hijacked by SARS-CoV-2 to promote its life cycle. Hydroxychloroquine (HCQ) has been also shown to specifically bind NTD and CTD to inhibit their interactions with nucleic acids, as well as to disrupt LLPS. Particularly, the unique structure of the HCQ-CTD complex offers a promising strategy for further design of anti-SARS-CoV-2 drugs with better affinity and specificity. The finding may indicate that LLPS is indeed druggable by small molecules, thus opening up a promising direction for drug discovery/design by targeting LLPS in general.

Caged Dexamethasone/Quercetin Nanoparticles, Formed of the Morphogenetic Active Inorganic Polyphosphate, are Strong Inducers of MUC5AC.

Inorganic polyphosphate (polyP) is a widely distributed polymer found from bacteria to animals, including marine species. This polymer exhibits morphogenetic as well as antiviral activity and releases metabolic energy after enzymatic hydrolysis also in human cells. In the pathogenesis of the coronavirus disease 2019 (COVID-19), the platelets are at the frontline of this syndrome. Platelets release a set of molecules, among them polyP. In addition, the production of airway mucus, the first line of body defense, is impaired in those patients. Therefore, in this study, amorphous nanoparticles of the magnesium salt of polyP (Mg-polyP-NP), matching the size of the coronavirus SARS-CoV-2, were prepared and loaded with the secondary plant metabolite quercetin or with dexamethasone to study their effects on the respiratory epithelium using human alveolar basal epithelial A549 cells as a model. The results revealed that both compounds embedded into the polyP nanoparticles significantly increased the steady-state-expression of the MUC5AC gene. This mucin species is the major mucus glycoprotein present in the secreted gel-forming mucus. The level of gene expression caused by quercetin or with dexamethasone, if caged into polyP NP, is significantly higher compared to the individual drugs alone. Both quercetin and dexamethasone did not impair the growth-supporting effect of polyP on A549 cells even at concentrations of quercetin which are cytotoxic for the cells. A possible mechanism of the effects of the two drugs together with polyP on mucin expression is proposed based on the scavenging of free oxygen species and the generation of ADP/ATP from the polyP, which is needed for the organization of the protective mucin-based mucus layer.

Extracellular ATP and Imbalance of CD4+ T Cell Compartment in Pediatric COVID-19.

Severe COVID-19 in children is rare, but the reasons underlying are unclear. Profound alterations in T cell responses have been well characterized in the course of adult severe COVID-19, but little is known about the T cell function in children with COVID-19. Here, we made three major observations in a cohort of symptomatic children with acute COVID-19: 1) a reduced frequency of circulating FoxP3+ regulatory T cells, 2) the prevalence of a TH17 polarizing microenvironment characterized by high plasma levels of IL-6, IL-23, and IL17A, and an increased frequency of CD4+ T cells expressing ROR-γt, the master regulator of TH17 development, and 3) high plasma levels of ATP together with an increased expression of the P2X7 receptor. Moreover, that plasma levels of ATP displayed an inverse correlation with the frequency of regulatory T cells but a positive correlation with the frequency of CD4+ T cells positive for the expression of ROR-γt. Collectively, our data indicate an imbalance in CD4+ T cell profiles during pediatric COVID-19 that might favor the course of inflammatory processes. This finding also suggests a possible role for the extracellular ATP in the acquisition of an inflammatory signature by the T cell compartment offering a novel understanding of the involved mechanisms.