Evidence of a dysregulated vitamin D endocrine system in SARS-CoV-2 infected patient's lung cells

Unmasking the complex roles of hypocalcemia in cancer, COVID-19, and sepsis: Engineered nanodelivery and diagnosis

Calcium (Ca2+) homeostasis is essential for maintaining physiological processes in the body. Disruptions in Ca2+ signaling can lead to various pathological conditions including inflammation, fibrosis, impaired immune function, and accelerated senescence. Hypocalcemia, a common symptom in diseases such as acute respiratory distress syndrome (ARDS), cancer, septic shock, and COVID-19, can have both potential protective and detrimental effects. This article explores the multifaceted role of Ca2+ dysregulation in inflammation, fibrosis, impaired immune function, and accelerated senescence, contributing to disease severity. Targeting Ca2+ signaling pathways may provide opportunities to develop novel therapeutics for age-related diseases and combat viral infections. However, the role of Ca2+ in viral infections is complex, and evidence suggests that hypocalcemia may have a protective effect against certain viruses, while changes in Ca2+ homeostasis can influence susceptibility to viral infections. The effectiveness and safety of Ca2+ supplements in COVID-19 patients remain a subject of ongoing research and debate. Further investigations are needed to understand the intricate interplay between Ca2+ signaling and disease pathogenesis.

SARS-CoV-2 infection of human lung epithelial cells induces TMPRSS-mediated acute fibrin deposition

Severe COVID-associated lung injury is a major confounding factor of hospitalizations and death with no effective treatments. Here, we describe a non-classical fibrin clotting mechanism mediated by SARS-CoV-2 infected primary lung but not other susceptible epithelial cells. This infection-induced fibrin formation is observed in all variants of SARS-CoV-2 infections, and requires thrombin but is independent of tissue factor and other classical plasma coagulation factors. While prothrombin and fibrinogen levels are elevated in acute COVID BALF samples, fibrin clotting occurs only with the presence of viral infected but not uninfected lung epithelial cells. We suggest a viral-induced coagulation mechanism, in which prothrombin is activated by infection-induced transmembrane serine proteases, such as ST14 and TMPRSS11D, on NHBE cells. Our finding reveals the inefficiency of current plasma targeted anticoagulation therapy and suggests the need to develop a viral-induced ARDS animal model for treating respiratory airways with thrombin inhibitors.

The Janus face of proliferating plasmablasts in dengue and COVID-19 infections

Introduction

B cells play an integral role in the immune response to both dengue fever and COVID-19. Prior scRNAseq analyses of peripheral plasmablasts in COVID-19 have revealed a heterogeneous population with distinct cell subsets associated with proliferation; prior studies in patients with dengue fever have likewise shown the presence of proliferative pre-plasmablasts in the circulation. These findings may have implications for disease severity. In this study, we sought to gain a mechanistic understanding of the intracellular processes in naive and memory B cells that are associated with and may lead to an expanded proliferative plasmablast population in the circulation.

Methods

We analyzed age-controlled (pediatric and adult), peripheral blood mononuclear cell scRNAseq datasets from patients infected with either dengue (primary or secondary) or COVID-19 (non-severe or severe) from previously published studies. Our preliminary analysis showed that pediatric patients with dengue and adults with COVID-19 had an expanded proliferative plasmablast (p-PB) population. By contrast, neither the adults with dengue nor the children with COVID-19 in our dataset had p-PBs. We used this distinctive preliminary signature to guide our analyses design and expanded our analyses to naive and memory B cells.

Results

In age/disease conditions with and without p-PBs, we found differences in cell sensing and activation, including via the B cell receptor and downstream signal transduction. Likewise, inflammation was mediated differently: relative to groups without p-PBs, those with p-PBs had increased expression of interferon response and S100 genes (particularly severe COVID-19). Furthermore, several transcription factors at the nexus of activation, inflammation, and cell fate decisions were expressed differently in groups with and without p-PBs.

Discussion

We used dengue and COVID-19 infections in adult and pediatric patients (focusing on naive B, memory B, and plasmablast cells) as a model to better understand the mechanisms that may give rise to p-PB populations in the circulation. Our results indicate that a more pro-inflammatory state in naive and memory B cells correlated with - and could influence the generation of- proliferating plasmablasts. Further exploration of these mechanisms will have implications for immune memory, vaccine development, and post-viral autoimmune syndromes.

Multi-Data Integration Towards a Global Understanding of the Neurological Impact of Human Brain Severe Acute Respiratory Syndrome Coronavirus 2 Infection

As the COVID-19 pandemic continues to unfold, numerous neurological symptoms emerge. The literature reports more and more manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) related to headache, dizziness, impaired consciousness, cognitive impairment, and motor disorders. Moreover, the infection of SARS-CoV-2 may have a durable neurological impact. ACE2/TMPRSS2 is the main entry point into cells for some strains of coronaviruses (CoVs), including SARS-CoV-2, which uses it to target the central nervous system (CNS). The aim of this study was to characterize the scope of the potential complex impact of a SARS-CoV-2 infection in the brain. It concerns different scales: the topographic, cognitive, sensorimotor, and genetic one. We investigated which cognitive and sensorimotor functions are associated with the brain regions where ACE2/TMPRSS2 is overexpressed, hypothesising that they might be particularly affected by the infection. Furthermore, overexpressed genes in these regions are likely to be impacted by COVID-19. This general understanding is crucial to establish the potential neurological manifestations of the infection. Data on mRNA expression levels of genes were provided by the Allen Institute for Brain Science (AIBS), and the localisation of brain functions by the LinkRbrain platform. The latter was also used to analyze the spatial overlap between ACE2/TMPRSS2 overexpression, and either function-specific brain activations or regional overexpression of other genes. The characterisation of these overexpressed genes was based on the GeneCards platform and the gene GSE164332 from the Gene Expression Omnibus database. We analysed the cognitive and sensorimotor functions whose role might be impaired, of which 88 have been categorised into seven groups: memory and recollection, motor function, pain, lucidity, emotion, sensory, and reward. Furthermore, we categorised the genes showing a significant increase in concentration of their mRNAs in the same regions where ACE2/TMPRSS2 mRNA levels are the highest. Eleven groups emerged from a bibliographical research: neurodegenerative disease, immunity, inflammation, olfactory receptor, cancer/apoptosis, executive function, senses, ischemia, motor function, myelination, and dependence. The results of this exploration could be in relation to the neurological symptoms of COVID-19. Furthermore, some genes from peripheral blood are already considered as biomarker of COVID-19. This method could generate new hypotheses to explore the neurological manifestations of COVID-19.

Vitamin D Endocrine System and COVID-19: Treatment with Calcifediol

The COVID-19 pandemic is the greatest challenge facing modern medicine and public health systems. The viral evolution of SARS-CoV-2, with the emergence of new variants with in-creased infectious potential, is a cause for concern. In addition, vaccination coverage remains in-sufficient worldwide. Therefore, there is a need to develop new therapeutic options, and/or to optimize the repositioning of drugs approved for other indications for COVID-19. This may include the use of calcifediol, the prohormone of the vitamin D endocrine system (VDES) as it may have potential useful effects for the treatment of COVID-19. We review the aspects associating COVID-19 with VDES and the potential use of calcifediol in COVID-19. VDES/VDR stimulation may enhance innate antiviral effector mechanisms, facilitating the induction of antimicrobial peptides/autophagy, with a critical modulatory role in the subsequent host reactive hyperinflammatory phase during COVID-19: By decreasing the cytokine/chemokine storm, regulating the renin–angiotensin–bradykinin system (RAAS), modulating neutrophil activity and maintaining the integrity of the pulmonary epithelial barrier, stimulating epithelial repair, and directly and indirectly decreasing the increased coagulability and prothrombotic tendency associated with severe COVID-19 and its complications. Available evidence suggests that VDES/VDR stimulation, while maintaining optimal serum 25OHD status, in patients with SARS-CoV-2 infection may significantly reduce the risk of acute respiratory distress syndrome (ARDS) and severe COVID-19, with possible beneficial effects on the need for mechanical ventilation and/or intensive care unit (ICU) admission, as well as deaths in the course of the disease. The pharmacokinetic and functional characteristics of calcifediol give it superiority in rapidly optimizing 25OHD levels in COVID-19. A pilot study and several observational intervention studies using high doses of calcifediol (0.532 mg on day 1 and 0.266 mg on days 3, 7, 14, 21, and 28) dramatically decreased the need for ICU admission and the mortality rate. We, therefore, propose to use calcifediol at the doses described for the rapid correction of 25OHD deficiency in all patients in the early stages of COVID-19, in association, if necessary, with the new oral antiviral agents.

Vitamin D Immune-Mediated Responses and SARS-CoV-2 Infection: Clinical Implications in COVID-19

Active vitamin D is a true steroid hormone with pleiotropic biological effects that go beyond the classical concept of bone metabolism regulation. In fact, adequate serum levels of 25-hydroxyvitamin D (>40 ng/mL) are required to support several biological functions, including the control of innate and adaptive immunity in course of infectious, inflammatory and autoimmune diseases. SARS-CoV-2 is responsible for the COVID-19 pandemic and deficient/insufficient serum levels of 25-hydroxyvitamin D are reported in very large cohorts of patients. Of note, vitamin D is involved in different pathophysiological processes, such as expression of SARS-CoV-2 receptor (ACE2), activation of innate (neutrophils with their extracellular traps, monocytes/macrophages, dendritic cells, natural killer cells) and adaptive (T and B lymphocytes) immune cells and clinical manifestations, such as coagulation/thrombotic disorders and acute respiratory distress syndrome. Randomized clinical trials regarding vitamin D supplementation in COVID-19 patients have shown favorable effects on the control of inflammation markers, arterial oxygen saturation/inspired fraction of oxygen ratio, admission to hospital intensive care units and mortality. A target of serum 25-hydroxyvitamin D > 50 ng/mL has been identified as protective for the course of COVID-19, potentially playing an ancillary role in the treatment of the disease.

Vitamin D Endocrine System and COVID-19

Preclinical data strongly suggest that the vitamin D endocrine system (VDES) may have extraskeletal effects. Cells of the immune and cardiovascular systems and lungs can express the vitamin D receptor, and overall these cells respond in a coherent fashion when exposed to 1,25-dihydroxyvitamin D, the main metabolite of the VDES. Supplementation of vitamin D-deficient subjects may decrease the risk of upper respiratory infections. The VDES also has broad anti-inflammatory and anti-thrombotic effects, and other mechanisms argue for a potential beneficial effect of a good vitamin D status on acute respiratory distress syndrome, a major complication of this SARS-2/COVID-19 infection. Activation of the VDES may thus have beneficial effects on the severity of COVID-19. Meta-analysis of observational data show that a better vitamin D status decreased the requirement of intensive care treatment or decreased mortality. A pilot study in Cordoba indicated that admission to intensive care was drastically reduced by administration of a high dose of calcifediol early after hospital admission for COVID-19. A large observational study in Barcelona confirmed that such therapy significantly decreased the odds ratio (OR) of mortality (OR = 0.52). This was also the conclusion of a retrospective study in five hospitals of Southern Spain. A retrospective study on all Andalusian patients hospitalized because of COVID-19, based on real-world data from the health care system, concluded that prescription of calcifediol (hazard ratio [HR] = 0.67) or vitamin D (HR = 0.75), 15 days before hospital admission decreased mortality within the first month. In conclusion, a good vitamin D status may have beneficial effects on the course of COVID-19. This needs to be confirmed by large, randomized trials, but in the meantime, we recommend (rapid) correction of 25 hydroxyvitamin D (25OHD) deficiency in subjects exposed to this coronavirus. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Rays of immunity: Role of sunshine vitamin in management of COVID-19 infection and associated comorbidities

The catastrophic pandemic engendered due to the Novel coronavirus (COVID-19) outbreak which causes severe clinical afflictions on the respiratory system has severely high morbidity and mortality rates. The requirement of novel compounds is at utmost importance due to lack of targeted drug molecule to treat the afflictions and restrict the viral infection and for the usage of prophylactic treatment to avoid the spread of the infection is of utmost importance. Vitamin D is one such naturally available multifunctional molecule, which plays an eminent role in the immune system and instigation of numerous cellular pathways further promoting health benefits and enhancing the human quality of life. This article reviews the current standpoint scenario and future prevalence of vitamin D supplementation in the management of covid-19 patients. Novel findings of Vitamin D suggest that along with regulation of cell growth, neuroprotective and mood-stabilizing effects, it regulates the immune response also modulate cytokine Interleukin-6 (IL-6) by inducing progesterone-induced blocking factor (PIBF), given the IL-6 levels are considerably high in COVID-19 patients which increases the further complications. Vitamin D also have its effect on angiotensin converting enzyme (ACEII) inhibitor through which the COVID-19 virus makes cell entry. Numerous research data elucidate the play of Vitamin D, in complications of COVID-19 including the most common comorbid conditions, neurological manifestations and immunological aspects makes it an ideal molecule for adjuvant therapy. Including Vitamin D as add-on therapy in the management of COVID-19 might aid the arrest of infection and helps fight this arduous epidemic.

A novel hypothesis for COVID-19 pathogenesis: Retinol depletion and retinoid signaling disorder

The SARS-CoV-2 virus has caused a worldwide COVID-19 pandemic. In less than a year and a half, more than 200 million people have been infected and more than four million have died. Despite some improvement in the treatment strategies, no definitive treatment protocol has been developed. The pathogenesis of the disease has not been clearly elucidated yet. A clear understanding of its pathogenesis will help develop effective vaccines and drugs. The immunopathogenesis of COVID-19 is characteristic with acute respiratory distress syndrome and multiorgan involvement with impaired Type I interferon response and hyperinflammation. The destructive systemic effects of COVID-19 cannot be explained simply by the viral tropism through the ACE2 and TMPRSS2 receptors. In addition, the recently identified mutations cannot fully explain the defect in all cases of Type I interferon synthesis. We hypothesize that retinol depletion and resulting impaired retinoid signaling play a central role in the COVID-19 pathogenesis that is characteristic for dysregulated immune system, defect in Type I interferon synthesis, severe inflammatory process, and destructive systemic multiorgan involvement. Viral RNA recognition mechanism through RIG-I receptors can quickly consume a large amount of the body's retinoid reserve, which causes the retinol levels to fall below the normal serum levels. This causes retinoid insufficiency and impaired retinoid signaling, which leads to interruption in Type I interferon synthesis and an excessive inflammation. Therefore, reconstitution of the retinoid signaling may prove to be a valid strategy for management of COVID-19 as well for some other chronic, degenerative, inflammatory, and autoimmune diseases.

Ramping Up Antimicrobial Peptides Against Severe Acute Respiratory Syndrome Coronavirus-2

Human-derived antimicrobial peptides (AMPs), such as defensins and cathelicidin LL-37, are members of the innate immune system and play a crucial role in early pulmonary defense against viruses. These AMPs achieve viral inhibition through a variety of mechanisms including, but not limited to, direct binding to virions, binding to and modulating host cell-surface receptors, blocking viral replication, and aggregation of viral particles and indirectly by functioning as chemokines to enhance or curb adaptive immune responses. Given the fact that we are in a pandemic of unprecedented severity and the urgent need for therapeutic options to combat severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), naturally expressed AMPs and their derivatives have the potential to combat coronavirus disease 2019 (COVID-19) and impede viral infectivity in various ways. Provided the fact that development of effective treatments is an urgent public health priority, AMPs and their derivatives are being explored as potential prophylactic and therapeutic candidates. Additionally, cell-based platforms such as human mesenchymal stem cell (hMSC) therapy are showing success in saving the lives of severely ill patients infected with SARS-CoV-2. This could be partially due to AMPs released from hMSCs that also act as immunological rheostats to modulate the host inflammatory response. This review highlights the utilization of AMPs in strategies that could be implemented as novel therapeutics, either alone or in combination with other platforms, to treat CoV-2-infected individuals.