Vitamin C: a novel regulator of neutrophil extracellular trap formation

Efficacy of dietary supplements on mortality and clinical outcomes in adults with sepsis and septic shock: A systematic review and network meta-analysis

AIM

The aim of this network meta-analysis (NMA) was to investigate the effects of different dietary supplements on the mortality and clinical status of adults with sepsis.

METHODS

We searched PubMed, EMBASE, and the Cochrane Library Central Register of Controlled Trials until February 2023. The inclusion criteria were: 1) randomized controlled trials (RCT)s; 2) adults suffering sepsis or septic shock; 3) evaluation of short- or long-mortality; and 4) publications between 1994 and 2023. The general information of studies and details of interventions were extracted. The primary outcome was short-term mortality (<90 days), and the secondary outcomes were long-term mortality (≥90 days), length of ICU and hospital stays, and duration of mechanical ventilation (MV). The risk of bias of RCTs was assessed using the Cochrane risk of bias tool 2 (ROB2). A random effect NMA was performed to rank the effect of each intervention using a frequentist approach.

RESULTS

Finally, 56 RCTs with 5957 participants met the criteria. Approximately, one-third of RCTs were low risk of bias. NMA analysis revealed that there was no treatment more effective in short- or long-term mortality than control or other interventions, except for magnesium (RR: 0.33, 95% CI: 0.14, 0.79; GRADE = low) and vitamin C (RR: 0.81, 95% CI: 0.67, 0.99; low certainty evidence), which had beneficial effects on short-term mortality. Moreover, eicosapentaenoic acid, gamma-linolenic acid, and antioxidants (EPA + GLA + AOs) combination was the most effective, and magnesium, vitamin D and vitamin C were the other effective approaches in terms of duration of MV, and ICU length of stay. There was no beneficial dietary supplement for hospital stay in these patients.

CONCLUSIONS

In septic patients, none of the dietary supplements had a substantial effect on mortality except for magnesium and vitamin C, which were linked to lower short-term mortality with low certainty of evidence. Further investigation into high-quality studies with the use of dietary supplements for sepsis should be highly discouraged.

Resveratrol prevents the release of neutrophil extracellular traps (NETs) by controlling hydrogen peroxide levels and nuclear elastase migration

Neutrophil extracellular traps (NETs) are defense mechanisms that trap and kill microorganisms and degrade cytokines. However, excessive production, dysregulation of suppression mechanisms, or inefficient removal of NETs can contribute to increased inflammatory response and the development of pathological conditions. Therefore, research has focused on identifying drugs that inhibit or delay the NET release process. Since reactive oxygen species (ROS) play a significant role in NET release, we aimed to investigate whether resveratrol (RSV), with a wide range of biological and pharmacological properties, could modulate NET release in response to different stimuli. Thus, human neutrophils were pretreated with RSV and subsequently stimulated with PMA, LPS, IL-8, or Leishmania. Our findings revealed that RSV reduced the release of NETs in response to all tested stimuli. RSV decreased hydrogen peroxide levels in PMA- and LPS-stimulated neutrophils, inhibited myeloperoxidase activity, and altered the localization of neutrophil elastase. RSV inhibition of NET generation was not mediated through A2A or A2B adenosine receptors or PKA. Based on the observed effectiveness of RSV in inhibiting NET release, our study suggests that this flavonoid holds potential as a candidate for treating NETs involving pathologies.

Neutrophil Extracellular Traps Regulate Surgical Brain Injury by Activating the cGAS-STING Pathway

Surgical brain injury (SBI), induced by neurosurgical procedures or instruments, has not attracted adequate attention. The pathophysiological process of SBI remains sparse compared to that of other central nervous system diseases thus far. Therefore, novel and effective therapies for SBI are urgently needed. In this study, we found that neutrophil extracellular traps (NETs) were present in the circulation and brain tissues of rats after SBI, which promoted neuroinflammation, cerebral edema, neuronal cell death, and aggravated neurological dysfunction. Inhibition of NETs formation by peptidylarginine deiminase (PAD) inhibitor or disruption of NETs with deoxyribonuclease I (DNase I) attenuated SBI-induced damages and improved the recovery of neurological function. We show that SBI triggered the activation of cyclic guanosine monophosphate-adenosine monophosphate synthase stimulator of interferon genes (cGAS-STING), and that inhibition of the cGAS-STING pathway could be beneficial. It is worth noting that DNase I markedly suppressed the activation of cGAS-STING, which was reversed by the cGAS product cyclic guanosine monophosphate-adenosine monophosphate (cGMP-AMP, cGAMP). Furthermore, the neuroprotective effect of DNase I in SBI was also abolished by cGAMP. NETs may participate in the pathophysiological regulation of SBI by acting through the cGAS-STING pathway. We also found that high-dose vitamin C administration could effectively inhibit the formation of NETs post-SBI. Thus, targeting NETs may provide a novel therapeutic strategy for SBI treatment, and high-dose vitamin C intervention may be a promising translational therapy with an excellent safety profile and low cost.

Investigational pharmacological agents for the treatment of ARDS

INTRODUCTION

Acute Respiratory Distress Syndrome (ARDS) is a heterogeneous form of lung injury with severe hypoxemia and bilateral infiltrates after an inciting event that results in diffuse lung inflammation with a high mortality rate. While research in COVID-related ARDS has resulted in several pharmacotherapeutic agents that have undergone successful investigation, non-COVID ARDS studies have not resulted in many widely accepted pharmacotherapeutic agents despite exhaustive research.

AREAS COVERED

The aim of this review is to discuss adjuvant pharmacotherapies targeting non-COVID Acute Lung Injury (ALI)/ARDS and novel therapeutics in COVID associated ALI/ARDS. In ARDS, variable data may support selective use of neuromuscular blocking agents, corticosteroids and neutrophil elastase inhibitors, but are not yet universally used. COVID-ALI/ARDS has data supporting the use of IL-6 monoclonal antibodies, corticosteroids, and JAK inhibitor therapy.

EXPERT OPINION

Although ALI/ARDS modifying pharmacological agents have been identified in COVID-related disease, the data in non-COVID ALI/ARDS has been less compelling. The increased use of more specific molecular phenotyping based on physiologic parameters and biomarkers, will ensure equipoise between groups, and will likely allow more precision in confirming pharmacological agent efficacy in future studies.

High-dose ascorbic acid potentiates immune modulation through STAT1 phosphorylation inhibition and negative regulation of PD-L1 in experimental sepsis

Sepsis is a complex, multifactorial syndrome characterized by a dysregulated host response to infection, leading to severe organ dysfunction and high mortality rates among critically ill patients. Hypovitaminosis C and vitamin C deficiency are frequently observed in septic patients, prompting interest in the potential therapeutic role of ascorbic acid. Although intravenous administration of ascorbic acid has been investigated in multiple clinical trials for sepsis treatment, the specific immunomodulatory mechanisms underlying its effects remain elusive. This study aimed to investigate the protective effects of high-dose ascorbic acid on experimental sepsis. Results show that intravenous administration of high-dose ascorbic acid (250 mg/kg) attenuated sepsis-induced organ dysfunctions in a cecal ligation and puncture (CLP)-induced septic mouse model. Ascorbic acid improved splenic cell apoptosis and increased the number of CD3+ T cells in septic mice induced by CLP. Furthermore, ascorbic acid downregulated PD-L1 expression in livers, reduced PD-1 expression in spleens, and inhibited the phosphorylation of STAT1 at Y701 in multiple organs of CLP-induced septic mice. The in vitro experiments also revealed that 800 μM ascorbic acid suppressed STAT1 phosphorylation and inhibited lipopolysaccharide (LPS) and IFN-γ-induced PD-L1 expression in macrophages. These findings suggest that ascorbic acid prevents sepsis-associated organ dysfunction through the p-STAT1/PD-L1 signaling pathway. Our study provides new insights into the potential therapeutic use of ascorbic acid in sepsis.

Vitamin C: Rationale for Its Use in Sepsis-Induced Acute Respiratory Distress Syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a life-threatening event that occurs in patients suffering from bacterial, fungal, or viral sepsis. Research performed over the last five decades showed that ARDS is a consequence of severe unrestrained systemic inflammation, which leads to injury of the lung's microvasculature and alveolar epithelium. ARDS leads to acute hypoxic/hypercapnic respiratory failure and death in a significant number of patients hospitalized in intensive care units worldwide. Basic and clinical research performed during the time since ARDS was first described has been unable to construct a pharmacological agent that will combat the inflammatory fire leading to ARDS. In-depth studies of the molecular pharmacology of vitamin C indicate that it can serve as a potent anti-inflammatory agent capable of attenuating the pathobiological events that lead to acute injury of the lungs and other body organs. This analysis of vitamin C's role in the treatment of ARDS includes a focused systematic review of the literature relevant to the molecular physiology of vitamin C and to the past performance of clinical trials using the agent.

A responsive hydrogel modulates innate immune cascade fibrosis to promote ocular surface reconstruction after chemical injury

Following an ocular chemical injury, the release of neutrophil extracellular traps (NETs) triggers an innate immune cascade fibrotic effect involving macrophages (Mø), which limits corneal repair. However, the interplay and mechanisms between NETs and macrophages, as well as the coordination between the innate immunity and corneal repair, remain challenging issues. Using a co-culture system, we report that chemical stimulation exacerbates the accumulation of reactive oxygen species (ROS) within the polymorphonuclear neutrophils, leading to NET formation and the activation of M2 macrophages, ultimately inducing pathological fibrosis of the ocular surface through the IL-10/STAT3/TGF-β1/Smad2 axis. Inspired by the locally formed acidic microenvironment mediated by innate acute inflammatory stimulation, we further integrate sericin with oxidized chitosan nanoparticles loaded with black phosphorus quantum dots (BPQDs) using Schiff base chemistry to construct a functional pH-responsive hydrogel. Following corneal injury, the hydrogel selectively releases BPQDs in response to the acidic environment, inhibiting the innate immune cascade fibrosis triggered by the PMN-ROS-NETs. Thus, corneal pathological fibrosis is alleviated and reshaping of the ocular surface takes place. These results represent a refinement of the mechanism of inherent immune effector cell interactions, and provide new research ideas for the construction of nano biomaterials that regulate pathological fibrosis.

Vitamin C deficiency in critically ill COVID-19 patients admitted to intensive care unit

Objectives

To determine vitamin C plasma kinetics, through the measurement of vitamin C plasma concentrations, in critically ill Coronavirus infectious disease 2019 (COVID-19) patients, identifying eventually the onset of vitamin C deficiency.

Design

Prospective, observational, single-center study.

Setting

Intensive Care Unit (ICU), Vall d'Hebron University Hospital, Barcelona. Study period from November 12th, 2020, to February 24th, 2021.

Patients

Patients who had a severe hypoxemic acute respiratory failure due to COVID-19 were included.

Interventions

Plasma vitamin C concentrations were measured on days 1, 5, and 10 of ICU admission. There were no vitamin C enteral nor parenteral supplementation. The supportive treatment was performed following the standard of care or acute respiratory distress syndrome (ARDS) patients.

Measurement

Plasma vitamin C concentrations were analyzed using an ultra-performance liquid chromatography (UPLC) system with a photodiode array detector (wavelength set to 245 nm). We categorized plasmatic levels of vitamin C as follows: undetectable: < 1,5 mg/L, deficiency: <2 mg/L. Low plasma concentrations: 2-5 mg/L; (normal plasma concentration: > 5 mg/L).

Main results

Forty-three patients were included (65% men; mean age 62 ± 10 years). The median Sequential Organ Failure Assessment (SOFA) score was 3 (1-4), and the Acute Physiology and Chronic Health disease Classification System (APACHE II) score was 13 (10-22). Five patients had shock. Bacterial coinfection was documented in 7 patients (16%). Initially all patients required high-flow oxygen therapy, and 23 (53%) further needed invasive mechanical ventilation during 21 (± 10) days. The worst PaO2/FIO2 registered was 93 (± 29). ICU and hospital survival were 77 and 74%, respectively. Low or undetectable levels remained constant throughout the study period in the vast majority of patients.

Conclusion

This observational study showed vitamin C plasma levels were undetectable on ICU admission in 86% of patients with acute respiratory failure due to COVID-19 pneumonia requiring respiratory support. This finding remained consistent throughout the study period.

The implication of neutrophil extracellular traps in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is an expanding worldwide health concern, and the underlying mechanisms contributing to its progression still need further exploration. Neutrophil extracellular traps (NETs) are intricate formations comprised of nuclear constituents and diverse antimicrobial granules that are released into the extracellular milieu by activated neutrophils upon various triggers, which play a pivotal part in the onset and advancement of NAFLD. NETs actively participate in the genesis of NAFLD by fostering oxidative stress and inflammation, ultimately resulting in hepatic fat accumulation and the escalation of liver injury. Recent insights into the interaction with other hepatic immune populations and mediators, such as macrophages and T regulatory cells, have revealed several important mechanisms that can trigger further liver injury. In conclusion, the formation of NETs emerged as an important factor in the development of NAFLD, offering a promising target for innovative therapeutic approaches against this debilitating condition. This comprehensive review seeks to compile existing studies exploring the involvement of NETs in the genesis of NAFLD and their influence on the immune response throughout the progression of NAFLD.

Modulatory role of vitamins A, B3, C, D, and E on skin health, immunity, microbiome, and diseases

Disruption of the skin barrier and immunity has been associated with several skin diseases, namely atopic dermatitis (AD), psoriasis, and acne. Resident and non-resident immune cells and the barrier system of the skin are integral to innate immunity. Recent advances in understanding skin microbiota have opened the scope of further understanding the various communications between these microbiota and skin immune cells. Vitamins, being one of the important micronutrients, have been reported to exert antioxidant, anti-inflammatory, and anti-microbial effects. The immunomodulatory action of vitamins can halt the progression of skin diseases, and thus, understanding the immuno-pharmacology of these vitamins, especially for skin diseases can pave the way for their therapeutic potential. At the same time, molecular and cellular markers modulated with these vitamins and their derivatives need to be explored. The present review is focused on significant vitamins (vitamins A, B3, C, D, and E) consumed as nutritional supplements to discuss the outcomes and scope of studies related to skin immunity, health, and diseases.

Effect of high-dose intravenous ascorbic acid on microcirculation and endothelial glycocalyx during sepsis and septic shock: a double-blind, randomized, placebo-controlled study

Previous studies indicate supplemental vitamin C improves microcirculation and reduces glycocalyx shedding in septic animals. Our randomized, double-blind, placebo-controlled trial aimed to investigate whether a high dose of intravenous ascorbic acid (AA) might improve microcirculation and affect glycocalyx in septic patients. In our study, 23 septic patients were supplemented with a high dose (50 mg/kg every 6 h) of intravenous AA or placebo for 96 h. Sublingual microcirculation was examined using a handheld Cytocam-incident dark field (IDF) video microscope. A sidestream dark field video microscope (SDF), connected to the GlycoCheck software (GlycoCheck ICU®; Maastricht University Medical Center, Maastricht, the Netherlands), was employed to observe glycocalyx. We found a significantly higher proportion of perfused small vessels (PPV) 6 h after the beginning of the trial in the experimental group compared with placebo. As an indicator of glycocalyx thickness, the perfused boundary region was lower in capillaries of the 5-9 μm diameter in the AA group than placebo after the first dose of AA. Our data suggest that high-dose parenteral AA tends to improve microcirculation and glycocalyx in the early period of septic shock. The study was retrospectively registered in the clinicaltrials.gov database on 26/02/2021 (registration number NCT04773717).

Effect of Antioxidant Supplementation on NET Formation Induced by LPS In Vitro; the Roles of Vitamins E and C, Glutathione, and N-acetyl Cysteine

Neutrophil extracellular traps (NETs) require reactive oxygen species (ROS) to eliminate pathogens by inducing oxidative stress. However, this process can also cause tissue damage to the host. Neutrophils contain high concentrations of vitamin C (1.5 mM) compared to the bloodstream (0.1 mM), and this antioxidant can interact with vitamin E and glutathione (GSH) inside the cell to maintain the redox balance. Previous studies have investigated the effect of vitamins E or C and N-acetyl cysteine (NAC) on NET formation, but the interactions of these molecules in neutrophils remain unknown. In this study, we investigated the effect of antioxidants alone and two combinations on NET formation and oxidative stress. Neutrophils were pre-loaded with GSH + NAC or vitamin E + vitamin C + GSH + NAC (termed ALL), and LPS-induced NET formation was assessed using fluorometry and immunofluorescence. Antioxidant effects were evaluated by measuring the total antioxidant capacity (TAC), GSH/GSSG ratio, ROS production, nitrite + nitrate levels, and lipid peroxidation. Our results showed that even low doses of antioxidants are capable of decreasing NETs. Furthermore, the combinations augmented TAC and GSH/GSSG ratio and decreased ROS, nitrites + nitrates, and malondialdehyde (MDA) levels in supplemented neutrophils in vitro.

Effect of intravenous vitamin C on adult septic patients: a systematic review and meta-analysis

Background

An increasing number of studies indicate that vitamin C (VC) reduces the mortality of adult septic patients, while some articles suggest otherwise. We performed this systematic review and meta-analysis to resolve the discrepancies in reported results concerning the efficacy of VC in septic patients.

Methods

We comprehensively searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled trials for randomized controlled trials (RCTs) evaluating the efficacy of intravenous VC (IVVC) on adult septic patients published from inception to November 28, 2022. The quality of outcomes for eligible studies was assessed using the Recommendations Assessment, Development, and Evaluation methodology. The results were analyzed using the pooled mean difference (MD) or risk ratio (RR) and 95% confidence intervals (CIs).

Results

Twenty-two studies (3,570 adult septic patients) were included. IVVC treatment did not improve 28-day mortality compared to the control group (RR, 0.92; 95% CI, 0.81-1.04; I2 = 26%; evidence risk, moderate). IVVC monotherapy decreased mortality (RR, 0.69; 95% CI, 0.52-0.93; I2 = 57%), whereas combination therapy did not affect mortality (RR, 1.03; 95% CI, 0.90-1.17; I2 =0%). IVVC had a trend to decrease the mortality of septic patients (RR, 0.83; 95% CI, 0.69-1.00; I2 = 33%) but did not affect septic shock patients (RR, 1.01; 95% CI, 0.85-1.21; I2 = 18%). IVVC reduced the duration of vasopressor use (MD, -8.45; 95% CI, -15.43 to -1.47; evidence risk, very low) but did not influence the incidence of AKI, ICU length of stay, duration of mechanical ventilation.

Conclusions

IVVC treatment did not improve the 28-day mortality in septic patients. Subgroup analysis indicated that VC had a trend to decrease the 28-day mortality in patients with sepsis but not septic shock. IVVC monotherapy, rather than combination therapy, decreased the 28-day mortality in septic patients. The findings imply that Hydrocortisone, Ascorbic acid, Thiamine (HAT) combination therapy is not superior to IVVC monotherapy for septic patients. These findings warrant further confirmation in future studies, which should also investigate the mechanisms underlying the enhanced efficacy of IVVC monotherapy in septic patients.

Systematic review registration

https://inplasy.com/.

The effect of neutrophil extracellular traps in venous thrombosis

Neutrophil extracellular traps (NETs) as special release products of neutrophils have received extensive attention. They are composed of decondensed chromatin and coated with nucleoproteins, including histones and some granulosa proteins. NETs can form a network structure to effectively capture and eliminate pathogens and prevent their spread. Not only that, recent studies have shown that NETs also play an important role in venous thrombosis. This review provides the most important updated evidence regarding the mechanism of NETs formation and the role of NETs in the process of venous thrombosis. The potential prophylactic and therapeutic value of NETs in venous thrombotic disease will also be discussed.

Listeriosis Risk Model for Cancer Patients Who Consume Ready-to-Eat Salad

The foodborne pathogen Listeria monocytogenes generally infects immunocompromised individuals, such as cancer patients, more frequently and with higher morbidity and mortality than the general population. Because of the anticipated risk associated with L. monocytogenes and other pathogens in produce, immunocompromised individuals are often placed on neutropenic diets that exclude fresh produce, though these risks have not been quantified. Therefore, this study developed a data-driven risk model for listeriosis in cancer patients who consume ready-to-eat (RTE) salads, consisting of leafy greens, cucumbers, and tomatoes, as influenced by kitchen-scale treatments and storage practices. Monte Carlo simulations were used to model the risk of invasive listeriosis during one chemotherapy cycle. Refrigerating all salad components decreased median risk by approximately one-half log. For refrigerated salads with no treatment, the predicted median risk was ≤ 4.3 × 10^-08. When salad ingredients were surface blanched with greens rinsed, the predicted risk decreased to 5.4 × 10^-10. Predicted risk was lowest (1.4 × 10^-13) for a blanched "salad" consisting of solely cucumbers and tomatoes. Interestingly, rinsing, as recommended by FDA only decreased median risk by 1 log. A sensitivity analysis revealed that the highly variable dose-response parameter k strongly influenced risk, indicating that reducing uncertainty in this variable may improve model accuracy. Overall, this study demonstrates that kitchen-scale pathogen reduction approaches have high risk-reduction efficacy and could be considered as an alternative to diets that exclude produce when making risk management decisions.

Neutrophil autophagy and NETosis in COVID-19: perspectives

The COVID-19 pandemic has caused substantial losses worldwide in people's lives, health, and property. Currently, COVID-19 is still prominent worldwide without any specific drug treatment. The SARS-CoV-2 pathogen is the cause of various systemic diseases, mainly acute pneumonia. Within the pathological process, neutrophils are recruited to infected sites, especially in the lungs, for the first stage of removing invading SARS-CoV-2 through a range of mechanisms. Macroautophagy/autophagy, a conserved autodegradation process in neutrophils, plays a crucial role in the neutrophil phagocytosis of pathogens. NETosis refers to neutrophil cell death, while auto-inflammatory factors and antigens release NETs. This review summarizes the latest research progress and provides an in-depth explanation of the underlying mechanisms of autophagy and NETosis in COVID-19. Furthermore, after exploring the relationship between autophagy and NETosis, we discuss potential targets and treatment options. This review keeps up with the latest research on COVID-19 from neutrophil autophagy and NETosis with a new perspective, which can guide the urgent development of antiviral drugs and provide guidance for the clinical treatment of COVID-19.Abbreviations: AKT1: AKT serine/threonine kinase 1; AMPK: AMP-activated protein kinase; AP: autophagosome; ARDS: acute respiratory distress syndrome; ATG: autophagy related; BECN1: beclin 1; cfDNA: cell-free DNA; COVID-19: coronavirus disease 2019; CQ: chloroquine; DMVs: double-membrane vesicles; ELANE/NE: elastase, neutrophil expressed; F3: coagulation factor III, tissue factor; HCQ: hydroxychloroquine; MAP1LC3/LC3: microtubule associated protein 1 light chain of 3; MPO: myeloperoxidase; MTORC1: mechanistic target of rapamycin kinase complex 1; NETs: neutrophil traps; NSP: nonstructural protein; PI3K: class I phosphoinositide 3-kinase; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; ROS: reactive oxygen species; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; SKP2: S-phase kinase associated protein 2; TCC: terminal complement complex; ULK1: unc-51 like.

Insight into SARS-CoV-2 Omicron variant immune escape possibility and variant independent potential therapeutic opportunities

The Omicron, the latest variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first detected in November 2021 in Botswana, South Africa. Compared to other variants of SARS-CoV-2, the Omicron is the most highly mutated, with 50 mutations throughout the genome, most of which are in the spike (S) protein. These mutations may help the Omicron to evade host immunity against the vaccine. Epidemiological studies suggest that Omicron is highly infectious and spreads rapidly, but causes significantly less severe disease than the wild-type strain and the other variants of SARS-CoV-2. With the increased transmissibility and a higher rate of re-infection, Omicron has now become a dominant variant worldwide and is predicted to be able to evade vaccine-induced immunity. Several clinical studies using plasma samples from individuals receiving two doses of US Food and Drugs Administration (FDA)-approved COVID-19 vaccines have shown reduced humoral immune response against Omicron infection, but T cell-mediated immunity was well preserved. In fact, T cell-mediated immunity protects against severe disease, and thus the disease caused by Omicron remains mild. In this review, I surveyed the current status of Omicron variant mutations and mechanisms of immune response in the context of immune escape from COVID-19 vaccines. I also discuss the potential implications of therapeutic opportunities that are independent of SARS-CoV-2 variants, including Omicron. A better understanding of vaccine-induced immune responses and variant-independent therapeutic interventions that include potent antiviral, antioxidant, and anti-cytokine activities may pave the way to reducing Omicron-related COVID-19 complications, severity, and mortality. Collectively, these insights point to potential research gaps and will aid in the development of new-generation COVID-19 vaccines and antiviral drugs to combat Omicron, its sublineages, or upcoming new variants of SARS-CoV-2.

Neutrophil extracellular traps: A novel target for the treatment of stroke

Stroke is a threatening cerebrovascular disease caused by thrombus with high morbidity and mortality rates. Neutrophils are the first to be recruited in the brain after stroke, which aggravate brain injury through multiple mechanisms. Neutrophil extracellular traps (NETs), as a novel regulatory mechanism of neutrophils, can trap bacteria and secret antimicrobial molecules, thereby degrading pathogenic factors and killing bacteria. However, NETs also exacerbate certain non-infectious diseases by activating autoimmune or inflammatory responses. NETs have been found to play important roles in the pathological process of stroke in recent years. In this review, the mechanisms of NETs formation, the physiological roles of NETs, and the dynamic changes of NETs after stroke are summarized. NETs participate in stroke through various mechanisms. NETs promote the coagulation cascade and interact with platelets to induce thrombosis. tPA induces the degranulation of neutrophils to form NETs, leading to hemorrhagic transformation and thrombolytic resistance. NETs aggravate stroke by mediating inflammation, atherosclerosis and vascular injury. In addition, the regulation of NETs in stroke, the potential of NETs as biomarker and the treatment of stroke targeting NETs are discussed. The increasing evidences suggest that NETs may be a potential target for stroke treatment. Inhibition of NETs formation or promotion of NETs degradation plays protective effects in stroke. However, how to avoid the adverse effects of NETs-targeted therapy deserves further study. In summary, this review provides a reference for the pathogenesis, drug targets, biomarkers and drug development of NETs in stroke.

High-Dose Intravenous Ascorbate in Sepsis, a Pro-Oxidant Enhanced Microbicidal Activity and the Effect on Neutrophil Functions

Vitamin C (ascorbic acid), a water-soluble essential vitamin, is well-known as an antioxidant and an essential substrate for several neutrophil functions. Because of (i) the importance of neutrophils in microbial control and (ii) the relatively low vitamin C level in neutrophils and in plasma during stress, vitamin C has been studied in sepsis (a life-threatening organ dysfunction from severe infection). Surprisingly, the supraphysiologic blood level of vitamin C (higher than 5 mM) after the high-dose intravenous vitamin C (HDIVC) for 4 days possibly induces the pro-oxidant effect in the extracellular space. As such, HDIVC demonstrates beneficial effects in sepsis which might be due to the impacts on an enhanced microbicidal activity through the improved activity indirectly via enhanced neutrophil functions and directly from the extracellular pro-oxidant effect on the organismal membrane. The concentration-related vitamin C properties are also observed in the neutrophil extracellular traps (NETs) formation as ascorbate inhibits NETs at 1 mM (or less) but facilitates NETs at 5 mM (or higher) concentration. The longer duration of HDIVC administration might be harmful in sepsis because NETs and pro-oxidants are partly responsible for sepsis-induced injuries, despite the possible microbicidal benefit. Despite the negative results in several randomized control trials, the short course HDIVC might be interesting to use in some selected groups, such as against anti-biotic resistant organisms. More studies on the proper use of vitamin C, a low-cost and widely available drug, in sepsis are warranted.

Biological Effects of Intravenous Vitamin C on Neutrophil Extracellular Traps and the Endothelial Glycocalyx in Patients with Sepsis-Induced ARDS

(1) Background: The disease-modifying mechanisms of high-dose intravenous vitamin C (HDIVC) in sepsis induced acute respiratory distress syndrome (ARDS) is unclear. (2) Methods: We performed a post hoc study of plasma biomarkers from subjects enrolled in the randomized placebo-controlled trial CITRIS-ALI. We explored the effects of HDIVC on cell-free DNA (cfDNA) and syndecan-1, surrogates for neutrophil extracellular trap (NET) formation and degradation of the endothelial glycocalyx, respectively. (3) Results: In 167 study subjects, baseline cfDNA levels in HDIVC (84 subjects) and placebo (83 subjects) were 2.18 ng/µL (SD 4.20 ng/µL) and 2.65 ng/µL (SD 3.87 ng/µL), respectively, p = 0.45. At 48-h, the cfDNA reduction was 1.02 ng/µL greater in HDIVC than placebo, p = 0.05. Mean baseline syndecan-1 levels in HDIVC and placebo were 9.49 ng/mL (SD 5.57 ng/mL) and 10.83 ng/mL (SD 5.95 ng/mL), respectively, p = 0.14. At 48 h, placebo subjects exhibited a 1.53 ng/mL (95% CI, 0.96 to 2.11) increase in syndecan-1 vs. 0.75 ng/mL (95% CI, 0.21 to 1.29, p = 0.05), in HDIVC subjects. (4) Conclusions: HDIVC infusion attenuated cell-free DNA and syndecan-1, biomarkers associated with sepsis-induced ARDS. Improvement of these biomarkers suggests amelioration of NETosis and shedding of the vascular endothelial glycocalyx, respectively.

Ascorbate Is a Primary Antioxidant in Mammals

Ascorbate (vitamin C in primates) functions as a cofactor for a number of enzymatic reactions represented by prolyl hydroxylases and as an antioxidant due to its ability to donate electrons, which is mostly accomplished through non-enzymatic reaction in mammals. Ascorbate directly reacts with radical species and is converted to ascorbyl radical followed by dehydroascorbate. Ambiguities in physiological relevance of ascorbate observed during in vivo situations could be attributed in part to presence of other redox systems and the pro-oxidant properties of ascorbate. Most mammals are able to synthesize ascorbate from glucose, which is also considered to be an obstacle to verify its action. In addition to animals with natural deficiency in the ascorbate synthesis, such as guinea pigs and ODS rats, three strains of mice with genetic removal of the responsive genes (GULO, RGN, or AKR1A) for the ascorbate synthesis have been established and are being used to investigate the physiological roles of ascorbate. Studies using these mice, along with ascorbate transporter (SVCT)-deficient mice, largely support its ability in protection against oxidative insults. While combined actions of ascorbate in regulating epigenetics and antioxidation appear to effectively prevent cancer development, pharmacological doses of ascorbate and dehydroascorbate may exert tumoricidal activity through redox-dependent mechanisms.

Molecular mechanisms and therapeutic target of NETosis in diseases

Evidence shows that neutrophils can protect the host against pathogens in multiple ways, including the formation and release of neutrophil extracellular traps (NETs). NETs are web‐like structures composed of fibers, DNA, histones, and various neutrophil granule proteins. NETs can capture and kill pathogens, including bacteria, viruses, fungi, and protozoa. The process of NET formation is called NETosis. According to whether they depend on nicotinamide adenine dinucleotide phosphate (NADPH), NETosis can be divided into two categories: “suicidal” NETosis and “vital” NETosis. However, NET components, including neutrophil elastase, myeloperoxidase, and cell‐free DNA, cause a proinflammatory response and potentially severe diseases. Compelling evidence indicates a link between NETs and the pathogenesis of a number of diseases, including sepsis, systemic lupus erythematosus, rheumatoid arthritis, small‐vessel vasculitis, inflammatory bowel disease, cancer, COVID‐19, and others. Therefore, targeting the process and products of NETosis is critical for treating diseases linked with NETosis. Researchers have discovered that several NET inhibitors, such as toll‐like receptor inhibitors and reactive oxygen species scavengers, can prevent uncontrolled NET development. This review summarizes the mechanism of NETosis, the receptors associated with NETosis, the pathology of NETosis‐induced diseases, and NETosis‐targeted therapy.

Pharmacological ascorbate as a novel therapeutic strategy to enhance cancer immunotherapy

Pharmacological ascorbate (i.e., intravenous infusions of vitamin C reaching ~ 20 mM in plasma) is under active investigation as an adjuvant to standard of care anti-cancer treatments due to its dual redox roles as an antioxidant in normal tissues and as a prooxidant in malignant tissues. Immune checkpoint inhibitors (ICIs) are highly promising therapies for many cancer patients but face several challenges including low response rates, primary or acquired resistance, and toxicity. Ascorbate modulates both innate and adaptive immune functions and plays a key role in maintaining the balance between pro and anti-inflammatory states. Furthermore, the success of pharmacological ascorbate as a radiosensitizer and a chemosensitizer in pre-clinical studies and early phase clinical trials suggests that it may also enhance the efficacy and expand the benefits of ICIs.

The Role and Efficacy of Vitamin C in Sepsis: A Systematic Review and Meta-Analysis

Clinical rationale for study: Despite advancements in critical care, the mortality rate of sepsis remains high, with an overall poor prognosis. There is a complex pathophysiology of a lethal cascade of cytokines and inflammatory proteins underlying sepsis. The use of vitamin C can theoretically suppress the inflammatory cascade but remains a questionable practice due to a lack of conclusive evidence. Aims of the study: To appraise the therapeutic role of vitamin C in sepsis. Materials and methods: A systematic review was conducted on PubMed, Embase, and the Central Cochrane Registry. The study included randomized clinical trials (RCTs) with vitamin C as an intervention arm in the septic patient population. For continuous variables, the difference in means (MD) and for discrete variables, the odds ratio (OR) was used. For effect sizes, a confidence interval of 95% was used. A p-value of less than 0.05 was used for statistical significance. The analysis was performed using a random-effects model irrespective of heterogeneity. Heterogeneity was evaluated using the I2 statistic. Results: 23 studies were included with the total sample size of 2712 patients. In patients treated with vitamin C, there was a statistically significant reduction in the mortality: OR = 0.778 (0.635 to 0.954), p = 0.016; the sequential organ failure assessment score (SOFA): MD = −0.749 (−1.115 to −0.383), p < 0.001; and the duration of vasopressor requirement: MD = −1.034 days (−1.622 to −0.445), p = 0.001. No significant difference was found in the hospital or ICU length of stay. Conclusions and clinical implications: Vitamin C treatment regimens were associated with reduced mortality, SOFA score, and vasopressor requirement compared to the control in sepsis. Given its low cost and minimal adverse effects, we strongly encourage further large, randomized trials to establish vitamin C as a standard of care in sepsis management.

Vitamins C and D and COVID-19 Susceptibility, Severity and Progression: An Evidence Based Systematic Review

Background and Objectives: Starting in early December 2019, the novel Coronavirus Disease (COVID-19) from infection with COVID-19 has caused a global pandemic. Many aspects of its pathogenesis and related clinical consequences are still unclear. Early diagnosis and dynamic monitoring of prognostic factors are essential to improve the ability to manage COVID-19 infection. This study aimed to provide an account of the role played by vitamins C and D on the onset, progression and severity of COVID-19. Clinical features and infection-related risk factors are also briefly discussed. Material and Methods: In March 2022, the main online databases were accessed. All the articles that investigate the possible role of vitamins C and D on COVID-19 susceptibility, severity and progression were considered. Results: The current evidence on vitamin C and D supplementation in patients with COVID-19 infection is inconsistent and controversial. In some studies, vitamins were used as coadjuvant of a formal experimental therapy, while in others as main treatment. Ethnicity and hospital setting (inpatient/outpatient) were also variable. Moreover, there was no consensus between studies in administration protocol: high heterogeneity in dosage, administration, and duration of the treatment were evident. Finally, some studies administered vitamins pre- and/or during COVID infection, in patients with different risk factors and infection severity. Conclusions: While waiting to develop a targeted, safe and effective therapy, it is important to investigate individual predisposition and proper disease management. Concluding, available data on the use of nutraceuticals in COVID-19 are inconsistent. However, there is a lack of evidence-based guidelines which recommend vitamin C and D supplementation in patients with COVID-19, and results from high quality randomised controlled trials (RCTs) are inconsistent. Current investigations so far are mostly observational, and include a relatively small sample size which can lead to biased results. Large-scale multicentre studies are therefore needed.

The Variable Nature of Vitamin C—Does It Help When Dealing with Coronavirus?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still spreading worldwide. For this reason, new treatment methods are constantly being researched. Consequently, new and already-known preparations are being investigated to potentially reduce the severe course of coronavirus disease 2019 (COVID-19). SARS-CoV-2 infection induces the production of pro-inflammatory cytokines and acute serum biomarkers in the host organism. In addition to antiviral drugs, there are other substances being used in the treatment of COVID-19, e.g., those with antioxidant properties, such as vitamin C (VC). Exciting aspects of the use of VC in antiviral therapy are its antioxidant and pro-oxidative abilities. In this review, we summarized both the positive effects of using VC in treating infections caused by SARS-CoV-2 in the light of the available research. We have tried to answer the question as to whether the use of high doses of VC brings the expected benefits in the treatment of COVID-19 and whether such treatment is the correct therapeutic choice. Each case requires individual assessment to determine whether the positives outweigh the negatives, especially in the light of populational studies concerning the genetic differentiation of genes encoding the solute carriers responsible forVC adsorption. Few data are available on the influence of VC on the course of SARS-CoV-2 infection. Deducing from already-published data, high-dose intravenous vitamin C (HDIVC) does not significantly lower the mortality or length of hospitalization. However, some data prove, among other things, its impact on the serum levels of inflammatory markers. Finally, the non-positive effect of VC administration is mainly neutral, but the negative effect is that it can result in urinary stones or nephropathies.

Vitamin C and its therapeutic potential in the management of COVID19

COVID19 has emerged as one of the worst pandemics in the history of mankind. Several vaccines have been approved by different government agencies worldwide, but data on their efficacy and safety are limited, and distribution remains a massive challenge. As per WHO, personal immunity is vital for protection against COVID19. Earlier, Vitamin C-mediated pathways have been shown to play critical role in boosting immunity attributed to its antioxidant properties. Recently, the involvement of such pathways in protection against COVID19 has been suggested. The controlled doses of Vitamin C administered through intravenous (IV) injections are being studied for determining its role in the prognosis of COVID19. In this article, we have discussed the potential role of Vitamin C in the management in COVID19 patients and presented recent clinical trials data. Additionally, we have elaborated the possibility of administering Vitamin C through inhalers in order to achieve local high concentration and the challenges of such approach.

Impact of Neutrophil Extracellular Traps on Thrombosis Formation: New Findings and Future Perspective

Thrombotic diseases seriously endanger human health, neutrophils and neutrophil extracellular traps (NETs) play an important role in abnormal thrombus formation. NETs are extracellular structures released by neutrophils upon stimulation by pathogens. NETs include neutrophil elastase (NE), myeloperoxidase (MPO), cathepsin G and other active substances. The network structure provided by NETs can prevent the spread of pathogens and effectively kill and eliminate pathogens. However, the components of NETs can also abnormally activate the coagulation pathway and participate in the formation of pathological thrombi. This review aims to summarize the mechanisms of NETs formation in detail; the research progress of NETs in venous thrombosis, arterial thrombosis, acquired disease-associated thrombosis, sepsis coagulation disorder; as well as the strategies to target NETs in thrombosis prevention and treatment.

Repurposing Vitamin C for Cancer Treatment: Focus on Targeting the Tumor Microenvironment

Simple Summary

The tumor microenvironment (TME) is a complicated network, and several promising TME-targeted therapies, such as immunotherapy and targeted therapies, are now facing problems over low response rates and drug resistance. Vitamin C (VitC) has been extensively studied as a dietary nutrient and multi-targeted natural drug for fighting against tumor cells. The focus has been recently on its crucial functions in the TME. Here, we discuss the potential mechanisms of VitC in several specialized microenvironments, characterize the current status of its preclinical and clinical applications, and offer suggestions for future studies. This article is intended to provide basic researchers and clinicians with a detailed picture of VitC targeting the tumor microenvironment.

Abstract

Based on the enhanced knowledge on the tumor microenvironment (TME), a more comprehensive treatment landscape for targeting the TME has emerged. This microenvironment provides multiple therapeutic targets due to its diverse characteristics, leading to numerous TME-targeted strategies. With multifaced activities targeting tumors and the TME, vitamin C is renown as a promising candidate for combination therapy. In this review, we present new advances in how vitamin C reshapes the TME in the immune, hypoxic, metabolic, acidic, neurological, mechanical, and microbial dimensions. These findings will open new possibilities for multiple therapeutic avenues in the fight against cancer. We also review the available preclinical and clinical evidence of vitamin C combined with established therapies, highlighting vitamin C as an adjuvant that can be exploited for novel therapeutics. Finally, we discuss unresolved questions and directions that merit further investigation.

IM156, a new AMPK activator, protects against polymicrobial sepsis

IM156, a novel biguanide with higher potency of AMP‐activated protein kinase activation than metformin, has inhibitory activity against angiogenesis and cancer. In this study, we investigated effects of IM156 against polymicrobial sepsis. Administration of IM156 significantly increased survival rate against caecal ligation and puncture (CLP)‐induced sepsis. Mechanistically, IM156 markedly reduced viable bacterial burden in the peritoneal fluid and peripheral blood and attenuated organ damage in a CLP‐induced sepsis model. IM156 also inhibited the apoptosis of splenocytes and the production of inflammatory cytokines including IL‐1β, IL‐6 and IL‐10 in CLP mice. Moreover, IM156 strongly inhibited the generation of reactive oxygen species and subsequent formation of neutrophil extracellular traps in response to lipopolysaccharide in neutrophils. Taken together, these results show that IM156 can inhibit inflammatory response and protect against polymicrobial sepsis, suggesting that IM156 might be a new treatment for sepsis.

NETosis and Neutrophil Extracellular Traps in COVID-19: Immunothrombosis and Beyond

Infection with SARS-CoV-2, the causative agent of the Coronavirus disease 2019 (COVID-19) pandemic, causes respiratory problems and multifaceted organ dysfunction. A crucial mechanism of COVID-19 immunopathy is the recruitment and activation of neutrophils at the infection site, which also predicts disease severity and poor outcomes. The release of neutrophil extracellular traps (NETs), occurring during a regulated form of neutrophil cell death known as NETosis, is a key effector function that mediates harmful effects caused by neutrophils. Abundant NETosis and NET generation have been observed in the neutrophils of many COVID-19 patients, leading to unfavorable coagulopathy and immunothrombosis. Moreover, excessive NETosis and NET generation are now more widely recognized as mediators of additional pathophysiological abnormalities following SARS-CoV-2 infection. In this minireview, we introduce subtypes of NET-producing neutrophils (e.g., low-density granulocytes) and explain the biological importance of NETs and the protein cargos of NETs in COVID-19. In addition, we discuss the mechanisms by which SARS-CoV-2 causes NETosis by upregulating viral processes (e.g., viral entry and replication) as well as host pro-NET mechanisms (e.g., proinflammatory mediator release, platelet activation, and autoantibody production). Furthermore, we provide an update of the main findings of NETosis and NETs in immunothrombosis and other COVID-19-related disorders, such as aberrant immunity, neurological disorders, and post COVID-19 syndromes including lung fibrosis, neurological disorder, tumor progression, and deteriorated chronic illness. Finally, we address potential prospective COVID-19 treatment strategies that target dysregulated NETosis and NET formation via inhibition of NETosis and promotion of NET degradation, respectively.

High-Dose Vitamin C Supplementation as a Legitimate Anti-SARS-CoV-2 Prophylaxis in Healthy Subjects—Yes or No?

Vitamin C has a number of acitvities that could contribute to its immune-modulating effects. The only question is whether we should provide ourselves with only the right level of it, or do we need much more during a pandemic? The possibility of reducing the incidence of viral diseases in a well-nourished population through the use of dietary supplements based on vitamin C is not supported in the literature. Despite this, the belief that an extra intake of vitamin C can increase the efficacy of the immune system is still popular and vitamin C is advertised as a remedy to prevent infectious disease. This article refers to the justification of the use of vitamin C in high doses as an anti-SARS-CoV-2 prophylaxis in healthy subjects. Does it make sense or not? As it turns out, any effects of vitamin C supplementation may be more prominent when the baseline vitamin C level is low, for example in physically active persons. People with hypovitaminosis C are more likely to respond to vitamin C administration. No studies regarding prevention of COVID-19 with high-dose vitamin C supplementation in healthy subjects were found.

Electrochemical Detection of Ascorbic Acid in Oranges at MWCNT-AONP Nanocomposite Fabricated Electrode

Ascorbic acid (AA) is an essential vitamin in the body, influencing collagen formation, as well as norepinephrine, folic acids, tryptophan, tyrosine, lysine, and neuronal hormone metabolism. This work reports on electrochemical detection of ascorbic acid (AA) in oranges using screen-print carbon electrodes (SPCEs) fabricated with multi-walled carbon nanotube- antimony oxide nanoparticle (MWCNT-AONP) nanocomposite. The nanocomposite-modified electrode displayed enhanced electron transfer and a better electrocatalytic reaction towards AA compared to other fabricated electrodes. The current response at the nanocomposite-modified electrode was four times bigger than the bare electrode. The sensitivity and limit of detection (LOD) at the nanocomposite modified electrode was 0.3663 [AA]/µM and 140 nM, respectively, with linearity from 0.16–0.640 μM and regression value R² = 0.985, using square wave voltammetry (SWV) for AA detection. Two well-separated oxidation peaks were observed in a mixed system containing AA and serotonin (5-HT); and the sensitivity and LOD were 0.0224 [AA]/µA, and 5.85 µΜ, respectively, with a concentration range from 23 to 100 µM (R² = 0.9969) for AA detection. The proposed sensor outperformed other AA sensors reported in the literature. The fabricated electrode showed great applicability with excellent recoveries ranging from 99 to 107 %, with a mean relative standard deviation (RSD) value of 3.52 % (n = 3) towards detecting AA in fresh oranges.

"MATH+" Multi-Modal Hospital Treatment Protocol for COVID-19 Infection: Clinical and Scientific Rationale

In December 2019, coronavirus disease 2019 (COVID-19), a severe respiratory illness caused by the new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China. The greatest impact that COVID-19 had was on intensive care units (ICUs), given that approximately 20% of hospitalized cases developed acute respiratory failure (ARF) requiring ICU admission. Based on the assumption that COVID-19 represented a viral pneumonia and no anti-coronaviral therapy existed, nearly all national and international health care societies recommended "supportive care only" avoiding other therapies outside of randomized controlled trials, with a specific prohibition against the use of corticosteroids in treatment. However, early studies of COVID-19-associated ARF reported inexplicably high mortality rates, with frequent prolonged durations of mechanical ventilation (MV), even from centers expert in such supportive care strategies. These reports led the authors to form a clinical expert panel called the Front-Line COVID-19 Critical Care Alliance (www.flccc.net). The panel collaboratively reviewed the emerging clinical, radiographic, and pathological reports of COVID-19 while initiating multiple discussions among a wide clinical network of front-line clinical ICU experts from initial outbreak areas in China, Italy, and New York. Based on the shared early impressions of "what was working and what wasn't working", the increasing medical journal publications and the rapidly accumulating personal clinical experiences with COVID-19 patients, a treatment protocol was created for the hospitalized patients based on the core therapies of methylprednisolone, ascorbic acid, thiamine, heparin and non-antiviral co-interventions (MATH+). This manuscript reviews the scientific and clinical rationale behind MATH+ based on published in-vitro, pre-clinical, and clinical data in support of each medicine, with a special emphasis of studies supporting their use in the treatment of patients with viral syndromes and COVID-19 specifically.

H2 Inhibits the Formation of Neutrophil Extracellular Traps

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NETs have been implicated as therapeutic targets to address inflammation and thrombotic tissue damage in conditions such as sepsis, acute respiratory disease syndrome, COVID-19, and CVDs.

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H₂ has been clinically and experimentally proven to ameliorate inflammation; however, the underlying molecular mechanisms remain elusive.

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Compared with control neutrophils, PMA-stimulated human neutrophils exposed to H₂ exhibited reduced citrullination of histones and release of NET components; mechanistically, H₂-mediated neutralization of HOCl produced during oxidative bursts suppresses DNA damage.

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Inhalation of H₂ inhibited the formation and release of NET components in the blood and BAL of the LPS-induced sepsis in mice and aged mini pigs.

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H₂ therapy is potentially a new therapeutic strategy for inflammatory diseases involving NETs associated with excessive neutrophil activation.

Neutrophil extracellular traps (NETs) contribute to inflammatory pathogenesis in numerous conditions, including infectious and cardiovascular diseases, and have attracted attention as potential therapeutic targets. H₂ acts as an antioxidant and has been clinically and experimentally proven to ameliorate inflammation. This study was performed to investigate whether H₂ could inhibit NET formation and excessive neutrophil activation. Neutrophils isolated from the blood of healthy volunteers were stimulated with phorbol-12-myristate-13-acetate (PMA) or the calcium ionophore A23187 in H₂-exposed or control media. Compared with control neutrophils, PMA- or A23187-stimulated human neutrophils exposed to H₂ exhibited reduced neutrophil aggregation, citrullination of histones, membrane disruption by chromatin complexes, and release of NET components. CXCR4^high neutrophils are highly prone to NETs, and H₂ suppressed Ser-139 phosphorylation in H2AX, a marker of DNA damage, thereby suppressing the induction of CXCR4 expression. H₂ suppressed both myeloperoxidase chlorination activity and production of reactive oxygen species to the same degree as N-acetylcysteine and ascorbic acid, while showing a more potent ability to inhibit NET formation than these antioxidants do in PMA-stimulated neutrophils. Although A23187 formed NETs in a reactive oxygen species–independent manner, H₂ inhibited A23187-induced NET formation, probably via direct inhibition of peptidyl arginine deiminase 4-mediated histone citrullination. Inhalation of H₂ inhibited the formation and release of NET components in the blood and bronchoalveolar lavage fluid in animal models of lipopolysaccharide-induced sepsis (mice and aged mini pigs). Thus, H₂ therapy can be a novel therapeutic strategy for NETs associated with excessive neutrophil activation.

Intravenous vitamin C administration to patients with septic shock: a pilot randomised controlled trial

BACKGROUND

Intravenous vitamin C administration in septic shock may have a sparing effect on vasopressor requirements, and vitamin C's enzyme cofactor functions provide a mechanistic rationale. Our study aimed to determine the effect of intravenous vitamin C administration on vasopressor requirements and other outcomes in patients with septic shock.

METHODS

This was a double-blind, randomised placebo-controlled trial in 40 patients with septic shock who were randomised (1:1) to receive intravenous vitamin C (at a dose of 25 mg/kg of body weight every 6 h) or placebo (intravenous 5% dextrose) for up to 96 h, or until death or discharge. The primary outcome was intravenous vasopressor requirements (dose and duration), and secondary outcomes included Sequential Organ Failure Assessment (SOFA) scores, intensive care unit (ICU) and hospital length of stay, and mortality. In addition, blood samples were collected to determine vitamin C kinetics and inflammatory marker concentrations.

RESULTS

Median plasma vitamin C concentrations were deficient at baseline (9.2 [4.4, 12] µmol/L) and increased to 408 (227, 560) µmol/L following 72 h of intervention. The mean duration of intravenous vasopressor infusion in the vitamin C group was 48 (95% CI 35-62) hours and in the placebo group was 54 (95% CI 41-62) hours (p = 0.52). The dose of vasopressor delivered over time was comparable between the two groups, as were SOFA scores (p > 0.05). The median ICU length of stay in the intervention group was 3.8 (2.2, 9.8) days versus 7.1 (3.1, 20) days in the placebo group (p = 0.12). The median hospital length of stay for the vitamin C group was 18 (11, 35) days versus 22 (10, 52) days for the placebo group (p = 0.65). Mortality was comparable between the two groups (p > 0.05). Of the inflammatory markers, neutrophil counts were elevated in the vitamin C group relative to placebo by 72 h (p = 0.01). C-reactive protein and myeloperoxidase concentrations were elevated at baseline, however, the two groups were comparable over time (p > 0.05).

CONCLUSIONS

Our pilot study indicated that intravenous vitamin C did not provide significant decreases in the mean dose or duration of vasopressor infusion. Further research that takes into account the potential impact of intervention timing, dose and duration, and location of trial, may provide more definitive evidence.

TRIAL REGISTRATION

ACTRN12617001184369 (11/8/2017).

Vitamin C improves microvascular reactivity and peripheral tissue perfusion in septic shock patients

Background

Vitamin C has potential protective effects through antioxidant and anti-inflammatory properties. However, the effect of vitamin C supplementation on microvascular function and peripheral tissue perfusion in human sepsis remains unknown. We aimed to determine vitamin C effect on microvascular endothelial dysfunction and peripheral tissue perfusion in septic shock patients.

Methods

Patients with septic shock were prospectively included after initial resuscitation. Bedside peripheral tissue perfusion and skin microvascular reactivity in response to acetylcholine iontophoresis in the forearm area were measured before and 1 h after intravenous vitamin C supplementation (40 mg/kg). Norepinephrine dose was not modified during the studied period.

Results

We included 30 patients with septic shock. SOFA score was 11 [8–14], SAPS II was 66 [54–79], and in-hospital mortality was 33%. Half of these patients had vitamin C deficiency at inclusion. Vitamin C supplementation strongly improved microvascular reactivity (AUC 2263 [430–4246] vs 5362 [1744–10585] UI, p = 0.0004). In addition, vitamin C supplementation improved mottling score (p = 0.06), finger-tip (p = 0.0003) and knee capillary refill time (3.7 [2.6–5.5] vs 2.9 [1.9–4.7] s, p < 0.0001), as well as and central-to-periphery temperature gradient (6.1 [4.9–7.4] vs 4.6 [3.4–7.0] °C, p < 0.0001). The beneficial effects of vitamin C were observed both in patients with or without vitamin C deficiency.

Conclusion

In septic shock patients being resuscitated, vitamin C supplementation improved peripheral tissue perfusion and microvascular reactivity whatever plasma levels of vitamin C.

ClinicalTrials.gov Identifier: NCT04778605 registered 26 January 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03891-8.

Exploring the Immune-Boosting Functions of Vitamins and Minerals as Nutritional Food Bioactive Compounds: A Comprehensive Review

Food components have long been recognized to play a fundamental role in the growth and development of the human body, conferring protective functionalities against foreign matter that can be severe public health problems. Micronutrients such as vitamins and minerals are essential to the human body, and individuals must meet their daily requirements through dietary sources. Micronutrients act as immunomodulators and protect the host immune response, thus preventing immune evasion by pathogenic organisms. Several experimental investigations have been undertaken to appraise the immunomodulatory functions of vitamins and minerals. Based on these experimental findings, this review describes the immune-boosting functionalities of micronutrients and the mechanisms of action through which these functions are mediated. Deficiencies of vitamins and minerals in plasma concentrations can lead to a reduction in the performance of the immune system functioning, representing a key contributor to unfavorable immunological states. This review provides a descriptive overview of the characteristics of the immune system and the utilization of micronutrients (vitamins and minerals) in preventative strategies designed to reduce morbidity and mortality among patients suffering from immune invasions or autoimmune disorders.

Modulation of neutrophil (dys)function by Ayurvedic herbs and its potential influence on SARS-CoV-2 infection

For centuries, traditional medicines of Ayurveda have been in use to manage infectious and non-infectious diseases. The key embodiment of traditional medicines is the holistic system of approach in the management of human diseases. SARS-CoV-2 (COVID-19) infection is an ongoing pandemic, which has emerged as the major health threat worldwide and is causing significant stress, morbidity and mortality. Studies from the individuals with SARS-CoV-2 infection have shown significant immune dysregulation and cytokine overproduction. Neutrophilia and neutrophil to lymphocyte ratio has been correlated to poor outcome due to the disease. Neutrophils, component of innate immune system, upon stimulation expel DNA along with histones and granular proteins to form extracellular traps (NETs). Although, these DNA lattices possess beneficial activity in trapping and eliminating pathogens, NETs may also cause adverse effects by inducing immunothrombosis and tissue damage in diseases including Type 2 Diabetes and atherosclerosis. Tissues of SARS-CoV-2 infected subjects showed microthrombi with neutrophil-platelet infiltration and serum showed elevated NETs components, suggesting large involvement and uncontrolled activation of neutrophils leading to pathogenesis and associated organ damage. Hence, traditional Ayurvedic herbs exhibiting anti-inflammatory and antioxidant properties may act in a manner that might prove beneficial in targeting over-functioning of neutrophils and there by promoting normal immune homeostasis. In the present manuscript, we have reviewed and discussed pathological importance of NETs formation in SARS-CoV-2 infections and discuss how various Ayurvedic herbs can be explored to modulate neutrophil function and inhibit NETs formation in the context of a) anti-microbial activity to enhance neutrophil function, b) immunomodulatory effects to maintain neutrophil mediated immune homeostasis and c) to inhibit NETs mediated thrombosis.

Nutrient modulation of viral infection-implications for COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has put focus on the importance of a healthy immune system for recovery from infection and effective response to vaccination. Several nutrients have been under attention because their nutritional statuses showed associations with the incidence or severity of COVID-19 or because they affect several aspects of immune function. Nutritional status, immune function, and viral infection are closely interrelated. Undernutrition impairs immune function, which can lead to increased susceptibility to viral infection, while viral infection itself can result in changes in nutritional status. Here, we review the roles of vitamins A, C, D, and E, and zinc, iron, and selenium in immune function and viral infection and their relevance to COVID-19.

NETosis in ischemic/reperfusion injuries: An organ-based review

Neutrophil extracellular trap (NETosis), the web-like structures induced by neutrophil death, is an important inflammatory mechanism of the immune system leading to reactive oxygen species production/coagulopathy, endothelial dysfunction, atherosclerosis, and ischemia. NETosis exerts its role through different mechanisms such as triggering Toll-like receptors, inflammatory cytokines, platelet aggregation, neutrophil activation/infiltration, and vascular impairment. NETosis plays a key role in the prognosis of coronary artery disease, ischemic injury of kidney, lung, gastrointestinal tract and skeletal muscles. In this review, we explored the molecular mechanisms involved in NETosis, and ischemic/reperfusion injuries in body organs.

Tick Immunobiology and Extracellular Traps: An Integrative Vision to Control of Vectors

Ticks are hematophagous ectoparasites that infest a diverse number of vertebrate hosts. The tick immunobiology plays a significant role in establishing and transmitting many pathogens to their hosts. To control tick infestations, the acaricide application is a commonly used method with severe environmental consequences and the selection of tick-resistant populations. With these drawbacks, new tick control methods need to be developed, and the immune system of ticks contains a plethora of potential candidates for vaccine design. Additionally, tick immunity is based on an orchestrated action of humoral and cellular immune responses. Therefore, the actors of these responses are the object of our study in this review since they are new targets in anti-tick vaccine design. We present their role in the immune response that positions them as feasible targets that can be blocked, inhibited, interfered with, and overexpressed, and then elucidate a new method to control tick infestations through the development of vaccines. We also propose Extracellular Traps Formation (ETosis) in ticks as a process to eliminate their natural enemies and those pathogens they transmit (vectorial capacity), which results attractive since they are a source of acting molecules with potential use as vaccines.

SARS-CoV-2 infection and oxidative stress: Pathophysiological insight into thrombosis and therapeutic opportunities

The current coronavirus disease 2019 (COVID-19) pandemic has presented unprecedented challenges to global health. Although the majority of COVID-19 patients exhibit mild-to-no symptoms, many patients develop severe disease and need immediate hospitalization, with most severe infections associated with a dysregulated immune response attributed to a cytokine storm. Epidemiological studies suggest that overall COVID-19 severity and morbidity correlate with underlying comorbidities, including diabetes, obesity, cardiovascular diseases, and immunosuppressive conditions. Patients with such comorbidities exhibit elevated levels of reactive oxygen species (ROS) and oxidative stress caused by an increased accumulation of angiotensin II and by activation of the NADPH oxidase pathway. Moreover, accumulating evidence suggests that oxidative stress coupled with the cytokine storm contribute to COVID-19 pathogenesis and immunopathogenesis by causing endotheliitis and endothelial cell dysfunction and by activating the blood clotting cascade that results in blood coagulation and microvascular thrombosis. In this review, we survey the mechanisms of how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces oxidative stress and the consequences of this stress on patient health. We further shed light on aspects of the host immunity that are crucial to prevent the disease during the early phase of infection. A better understanding of the disease pathophysiology as well as preventive measures aimed at lowering ROS levels may pave the way to mitigate SARS-CoV-2-induced complications and decrease mortality.

Embracing cancer immunotherapy with vital micronutrients

Immunotherapy is now commonly prescribed to cancer patients, but autoimmune-related adverse events are considerable. For severe, life-threatening side effects, cessation of therapy seems unavoidable, let alone intensive medical care required for patching up the adverse events. Even without serious adverse events, the response rates are too low and various combinatory regimens have been tried. However, toxicities are also added on, unless the adjuvant agents have remarkably few side effects. Actually, micronutrients are usually taken by a majority of cancer patients as nutritional support or to boost the immune function, let alone hoping to counteract treatment side effects. Recent studies have shown that combinations of micronutrients exert pleiotropic effects in controlling tumor growth and metastasis by modulating the tumor microenvironment, enhancing gut microbiota immune functions, and providing adjunct nutritional support to micronutrient deficient cancer patients. A higher than recommended dietary allowance micronutrient dose is proposed to reduce the toxic free radicals generated as a result of immunotherapy and tumor metabolism. This is not only helpful for managing treatment side effects but also enhancing treatment efficacy. As micronutrient supplementation is also useful to improve patients’ quality of life, prolong survival, and sustain compliance to immunotherapy, further investigations are mandatory.

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute respiratory illness characterised by bilateral chest radiographical opacities with severe hypoxaemia due to non-cardiogenic pulmonary oedema. The COVID-19 pandemic has caused an increase in ARDS and highlighted challenges associated with this syndrome, including its unacceptably high mortality and the lack of effective pharmacotherapy. In this Seminar, we summarise current knowledge regarding ARDS epidemiology and risk factors, differential diagnosis, and evidence-based clinical management of both mechanical ventilation and supportive care, and discuss areas of controversy and ongoing research. Although the Seminar focuses on ARDS due to any cause, we also consider commonalities and distinctions of COVID-19-associated ARDS compared with ARDS from other causes.

Vitamin supplementation as a potential adjunctive therapeutic approach for COVID-19: biological and clinical plausibility

The recent pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Disease 2019 (COVID-19) has introduced itself into the human population in the 21st century after the coronavirus diseases SARS-CoV and Middle East respiratory syndrome (MERS-CoV). Major investigations are underway worldwide in the search for pharmaceutical interventions for COVID-19 and many agents are administered in off-label routes. Several cases are under study to check or restrict clinical manifestations of COVID-19. According to the fact that the efficacy of some micro-nutrients like vitamins is proven to treat or prevent infectious diseases because of their antimicrobial and immunomodulatory activity, the potential role of vitamins in the COVID-19 treatment or prevention must be considered.

The cytokine storms of COVID-19, H1N1 influenza, CRS and MAS compared. Can one sized treatment fit all?

An analysis of published data appertaining to the cytokine storms of COVID-19, H1N1 influenza, cytokine release syndrome (CRS), and macrophage activation syndrome (MAS) reveals many common immunological and biochemical abnormalities. These include evidence of a hyperactive coagulation system with elevated D-dimer and ferritin levels, disseminated intravascular coagulopathy (DIC) and microthrombi coupled with an activated and highly permeable vascular endothelium. Common immune abnormalities include progressive hypercytokinemia with elevated levels of TNF-α, interleukin (IL)-6, and IL-1β, proinflammatory chemokines, activated macrophages and increased levels of nuclear factor kappa beta (NFκB). Inflammasome activation and release of damage associated molecular patterns (DAMPs) is common to COVID-19, H1N1, and MAS but does not appear to be a feature of CRS. Elevated levels of IL-18 are detected in patients with COVID-19 and MAS but have not been reported in patients with H1N1 influenza and CRS. Elevated interferon-γ is common to H1N1, MAS, and CRS but levels of this molecule appear to be depressed in patients with COVID-19. CD4+ T, CD8+ and NK lymphocytes are involved in the pathophysiology of CRS, MAS, and possibly H1N1 but are reduced in number and dysfunctional in COVID-19. Additional elements underpinning the pathophysiology of cytokine storms include Inflammasome activity and DAMPs. Treatment with anakinra may theoretically offer an avenue to positively manipulate the range of biochemical and immune abnormalities reported in COVID-19 and thought to underpin the pathophysiology of cytokine storms beyond those manipulated via the use of, canakinumab, Jak inhibitors or tocilizumab. Thus, despite the relative success of tocilizumab in reducing mortality in COVID-19 patients already on dexamethasone and promising results with Baricitinib, the combination of anakinra in combination with dexamethasone offers the theoretical prospect of further improvements in patient survival. However, there is currently an absence of trial of evidence in favour or contravening this proposition. Accordingly, a large well powered blinded prospective randomised controlled trial (RCT) to test this hypothesis is recommended.