Intoxication With Endogenous Angiotensin II: A COVID-19 Hypothesis

Takotsubo syndrome as an outcome of the use of checkpoint inhibitor therapy in patients with COVID-19

Takotsubo Syndrome (TS) is a heart disease caused by extreme exposure of the body to physical or psychological stress. In the context of COVID-19, the virus can be a significant source of stress, with particular attention being paid to the cytokine storm as a cause of damage to the body. New research shows that the production of specific cytokines is linked to the activation of immune checkpoint proteins such as PD-1, PD-L1, and CTLA-4 on T cells. Although initially beneficial in combating infections, it can suppress defense and aid in disease progression. Therefore, checkpoint inhibitor therapy has been highlighted beyond oncological therapies, given its effectiveness in strengthening the immune system. However, this treatment can lead to excessive immune responses, inflammation, and stress on the heart, which can cause Takotsubo Syndrome in patients. Several studies investigate the direct link between this therapy and cardiac injuries in these patients, which can trigger TS. From this perspective, we must delve deeper into this treatment and consider its effects on the prognosis against SARS-CoV-2 infection.

[Interaction of somatic findings and psychiatric symptoms in COVID-19. A scoping review]

An infection with SARS-CoV‑2 can affect the central nervous system, leading to neurological as well as psychiatric symptoms. In this respect, mechanisms of inflammation seem to be of much greater importance than the virus itself. This paper deals with the possible contributions of organic changes to psychiatric symptomatology and deals especially with delirium, cognitive symptoms, depression, anxiety, posttraumatic stress disorder and psychosis. Processes of neuroinflammation with infection of capillary endothelial cells and activation of microglia and astrocytes releasing high amounts of cytokines seem to be of key importance in all kinds of disturbances. They can lead to damage in grey and white matter, impairment of cerebral metabolism and loss of connectivity. Such neuroimmunological processes have been described as a organic basis for many psychiatric disorders, as affective disorders, psychoses and dementia. As the activation of the glia cells can persist for a long time after the offending agent has been cleared, this can contribute to long term sequalae of the infection.

Long COVID as a Tauopathy: Of "Brain Fog" and "Fusogen Storms"

Long COVID, also called post-acute sequelae of SARS-CoV-2, is characterized by a multitude of lingering symptoms, including impaired cognition, that can last for many months. This symptom, often called "brain fog", affects the life quality of numerous individuals, increasing medical complications as well as healthcare expenditures. The etiopathogenesis of SARS-CoV-2-induced cognitive deficit is unclear, but the most likely cause is chronic inflammation maintained by a viral remnant thriving in select body reservoirs. These viral sanctuaries are likely comprised of fused, senescent cells, including microglia and astrocytes, that the pathogen can convert into neurotoxic phenotypes. Moreover, as the enteric nervous system contains neurons and glia, the virus likely lingers in the gastrointestinal tract as well, accounting for the intestinal symptoms of long COVID. Fusogens are proteins that can overcome the repulsive forces between cell membranes, allowing the virus to coalesce with host cells and enter the cytoplasm. In the intracellular compartment, the pathogen hijacks the actin cytoskeleton, fusing host cells with each other and engendering pathological syncytia. Cell-cell fusion enables the virus to infect the healthy neighboring cells. We surmise that syncytia formation drives cognitive impairment by facilitating the "seeding" of hyperphosphorylated Tau, documented in COVID-19. In our previous work, we hypothesized that the SARS-CoV-2 virus induces premature endothelial senescence, increasing the permeability of the intestinal and blood-brain barrier. This enables the migration of gastrointestinal tract microbes and/or their components into the host circulation, eventually reaching the brain where they may induce cognitive dysfunction. For example, translocated lipopolysaccharides or microbial DNA can induce Tau hyperphosphorylation, likely accounting for memory problems. In this perspective article, we examine the pathogenetic mechanisms and potential biomarkers of long COVID, including microbial cell-free DNA, interleukin 22, and phosphorylated Tau, as well as the beneficial effect of transcutaneous vagal nerve stimulation.

Coronavirus disease 2019 and cardiovascular disease

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus behind the coronavirus disease 2019 (COVID-19) pandemic, is a type of RNA virus that is nonsegmented. Cardiovascular diseases (CVDs) increase the mortality risk of patients. In this review article, we overview the existing evidence regarding the potential mechanisms of myocardial damage in coronavirus disease 2019 (COVID-19) patients. Having a comprehensive knowledge of the cardiovascular damage caused by SARS-CoV-2 and its underlying mechanisms is essential for providing prompt and efficient treatment, ultimately leading to a reduction in mortality rates. Severe COVID-19 causes acute respiratory distress syndrome and shock in patients. In addition, awareness regarding COVID-19 cardiovascular manifestations has increased, including the adverse impact on prognosis with cardiovascular involvement. Angiotensin-converting enzyme 2 receptor may play a role in acute myocardial injury caused by SARS-CoV-2 infection. COVID-19 patients experiencing heart failure may have their condition exacerbated by various contributing factors and mechanisms. Increased oxygen demand, myocarditis, stress cardiomyopathy, elevated pulmonary pressures, and venous thrombosis are potential health issues. The combination of these factors may lead to COVID-19-related cardiogenic shock, resulting in acute systolic heart failure. Extracorporeal membrane oxygenation (ECMO) and left ventricular assist devices (LVADs) are treatment options when inotropic support fails for effective circulatory support. To ensure effective COVID-19-related cardiovascular disease (CVD) surveillance, it is crucial to closely monitor the future host adaptation, viral evolution, and transmissibility of SARS-CoV-2, given the virus's pandemic potential.

Diabetes, COVID-19, and questions unsolved

Recent evidence suggests a role for Diabetes Mellitus in adverse outcomes from COVID-19 infection; yet the underlying mechanisms are not clear. Moreover, attention has turned to prophylactic vaccination to protect the population from COVID-19-related illness and mortality. We performed a comprehensive peer-reviewed literature search on an array of key terms concerning diabetes and COVID-19 seeking to address the following questions: 1. What role does diabetes play as an accelerator for adverse outcomes in COVID-19?; 2. What mechanisms underlie the differences in outcomes seen in people with diabetes?; 3. Are vaccines against COVID-19 efficacious in people with diabetes? The current literature demonstrates that diabetes is associated with an increased risk of adverse outcomes from COVID-19 infection, and post-COVID sequelae. Potential mechanisms include dysregulation of Angiotensin Converting Enzyme 2, Furin, CD147, and impaired immune cell responses. Hyperglycaemia is a key exacerbator of these mechanisms. Limited studies are available on COVID-19 vaccination in people with diabetes; however, the current literature suggests that vaccination is protective against adverse outcomes for this population. In summary, people with diabetes are a high-risk group that should be prioritised in vaccination efforts. Glycaemic optimisation is paramount to protecting this group from COVID-19-associated risk. Unsolved questions remain as to the molecular mechanisms underlying the adverse outcomes seen in people with diabetes; the functional impact of post-COVID symptoms on people with diabetes, their persistence, and management; how long-term vaccine efficacy is affected by diabetes, and the antibody levels that confer protection from adverse outcomes in COVID-19.

Recent Developments in Protein Lactylation in PTSD and CVD: Novel Strategies and Targets

In 1938, Corneille Heymans received the Nobel Prize in physiology for discovering that oxygen sensing in the aortic arch and carotid sinus was mediated by the nervous system. The genetics of this process remained unclear until 1991 when Gregg Semenza while studying erythropoietin, came upon hypoxia-inducible factor 1, for which he obtained the Nobel Prize in 2019. The same year, Yingming Zhao found protein lactylation, a posttranslational modification that can alter the function of hypoxia-inducible factor 1, the master regulator of cellular senescence, a pathology implicated in both post-traumatic stress disorder (PTSD) and cardiovascular disease (CVD). The genetic correlation between PTSD and CVD has been demonstrated by many studies, of which the most recent one utilizes large-scale genetics to estimate the risk factors for these conditions. This study focuses on the role of hypertension and dysfunctional interleukin 7 in PTSD and CVD, the former caused by stress-induced sympathetic arousal and elevated angiotensin II, while the latter links stress to premature endothelial cell senescence and early vascular aging. This review summarizes the recent developments and highlights several novel PTSD and CVD pharmacological targets. They include lactylation of histone and non-histone proteins, along with the related biomolecular actors such as hypoxia-inducible factor 1α, erythropoietin, acid-sensing ion channels, basigin, and Interleukin 7, as well as strategies to delay premature cellular senescence by telomere lengthening and resetting the epigenetic clock.

ACE2 Receptor and TMPRSS2 Protein Expression Patterns in the Human Brainstem Reveal Anatomical Regions Potentially Vulnerable to SARS-CoV-2 Infection

Angiotensin-converting enzyme 2 receptor (ACE2R) is a transmembrane protein expressed in various tissues throughout the body that plays a key role in the regulation of blood pressure. Recently, ACE2R has gained significant attention due to its involvement in the pathogenesis of COVID-19, the disease caused by the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2). While ACE2 receptors serve as entry points for the novel coronavirus, Transmembrane Serine Protease 2 (TMPRSS2), an enzyme located on the cell membrane, is required for SARS-CoV-2 S protein priming. Even though numerous studies have assessed the effects of COVID-19 on the brain, very little information is available concerning the distribution of ACE2R and TMPRSS2 in the human brain, with particular regard to their topographical expression in the brainstem. In this study, we investigated the expression of ACE2R and TMPRSS2 in the brainstem of 18 adult subjects who died due to pneumonia/respiratory insufficiency. Our findings indicate that ACE2R and TMPRSS2 are expressed in neuronal and glial cells of the brainstem, particularly at the level of the vagal nuclei of the medulla and the midbrain tegmentum, thus confirming the expression and anatomical localization of these proteins within specific human brainstem nuclei. Furthermore, our findings help to define anatomically susceptible regions to SARS-CoV-2 infection in the brainstem, advancing knowledge on the neuropathological underpinnings of neurological manifestations in COVID-19.

The spike effect of acute respiratory syndrome coronavirus 2 and coronavirus disease 2019 vaccines on blood pressure

Among the various comorbidities potentially worsening the clinical outcome in patients hospitalized for the acute respiratory syndrome coronavirus-2 (SARS-CoV-2), hypertension is one of the most prevalent. However, the basic mechanisms underlying the development of severe forms of coronavirus disease 2019 (COVID-19) among hypertensive patients remain undefined and the direct association of hypertension with outcome in COVID-19 is still a field of debate. Experimental and clinical data suggest that SARS-CoV-2 infection promotes a rise in blood pressure (BP) during the acute phase of infection. Acute increase in BP and high in-hospital BP variability may be tied with acute organ damage and a worse outcome in patients hospitalized for COVID-19. In this context, the failure of the counter-regulatory renin-angiotensin-system (RAS) axis is a potentially relevant mechanism involved in the raise in BP. It is well recognized that the efficient binding of the Spike (S) protein to angiotensin converting enzyme 2 (ACE2) receptors mediates the virus entry into cells. Internalization of ACE2, downregulation and malfunction predominantly due to viral occupation, dysregulates the protective RAS axis with increased generation and activity of angiotensin (Ang) II and reduced formation of Ang1,7. Thus, the imbalance between Ang II and Ang1-7 can directly contribute to excessively rise BP in the acute phase of SARS-CoV-2 infection. A similar mechanism has been postulated to explain the raise in BP following COVID-19 vaccination ("Spike Effect" similar to that observed during the infection of SARS-CoV-2). S proteins produced upon vaccination have the native-like mimicry of SARS-CoV-2 S protein's receptor binding functionality and prefusion structure and free-floating S proteins released by the destroyed cells previously targeted by vaccines may interact with ACE2 of other cells, thereby promoting ACE2 internalization and degradation, and loss of ACE2 activities.

Rethinking the Role of the Renin-Angiotensin System in the Pandemic Era of SARS-CoV-2

After assessing the levels of spread and severity of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, academic literature focused on the pathophysiology of coronavirus disease 2019 (COVID-19) [...].

Therapeutic advances in COVID-19

Over 2 years have passed since the start of the COVID-19 pandemic, which has claimed millions of lives. Unlike the early days of the pandemic, when management decisions were based on extrapolations from in vitro data, case reports and case series, clinicians are now equipped with an armamentarium of therapies based on high-quality evidence. These treatments are spread across seven main therapeutic categories: anti-inflammatory agents, antivirals, antithrombotics, therapies for acute hypoxaemic respiratory failure, anti-SARS-CoV-2 (neutralizing) antibody therapies, modulators of the renin-angiotensin-aldosterone system and vitamins. For each of these treatments, the patient population characteristics and clinical settings in which they were studied are important considerations. Although few direct comparisons have been performed, the evidence base and magnitude of benefit for anti-inflammatory and antiviral agents clearly outweigh those of other therapeutic approaches such as vitamins. The emergence of novel variants has further complicated the interpretation of much of the available evidence, particularly for antibody therapies. Importantly, patients with acute and chronic kidney disease were under-represented in many of the COVID-19 clinical trials, and outcomes in this population might differ from those reported in the general population. Here, we examine the clinical evidence for these therapies through a kidney medicine lens.

Impaired VEGF-A-Mediated Neurovascular Crosstalk Induced by SARS-CoV-2 Spike Protein: A Potential Hypothesis Explaining Long COVID-19 Symptoms and COVID-19 Vaccine Side Effects?

Long coronavirus disease-19 (COVID-19) is a newly discovered syndrome characterized by multiple organ manifestations that persist for weeks to months, following the recovery from acute disease. Occasionally, neurological and cardiovascular side effects mimicking long COVID-19 have been reported in recipients of COVID-19 vaccines. Hypothetically, the clinical similarity could be due to a shared pathogenic role of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike (S) protein produced by the virus or used for immunization. The S protein can bind to neuropilin (NRP)-1, which normally functions as a coreceptor for the vascular endothelial growth factor (VEGF)-A. By antagonizing the docking of VEGF-A to NRP-1, the S protein could disrupt physiological pathways involved in angiogenesis and nociception. One consequence could be the increase in unbound forms of VEGF-A that could bind to other receptors. SARS-CoV-2-infected individuals may exhibit increased plasma levels of VEGF-A during both acute illness and convalescence, which could be responsible for diffuse microvascular and neurological damage. A few studies suggest that serum VEGF-A may also be a potential biomarker for long COVID-19, whereas evidence for COVID-19 vaccines is lacking and merits further investigation.

Long COVID and the Neuroendocrinology of Microbial Translocation Outside the GI Tract: Some Treatment Strategies

Similar to previous pandemics, COVID-19 has been succeeded by well-documented post-infectious sequelae, including chronic fatigue, cough, shortness of breath, myalgia, and concentration difficulties, which may last 5 to 12 weeks or longer after the acute phase of illness. Both the psychological stress of SARS-CoV-2 infection and being diagnosed with COVID-19 can upregulate cortisol, a stress hormone that disrupts the efferocytosis effectors, macrophages, and natural killer cells, leading to the excessive accumulation of senescent cells and disruption of biological barriers. This has been well-established in cancer patients who often experience unrelenting fatigue as well as gut and blood–brain barrier dysfunction upon treatment with senescence-inducing radiation or chemotherapy. In our previous research from 2020 and 2021, we linked COVID-19 to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) via angiotensin II upregulation, premature endothelial senescence, intestinal barrier dysfunction, and microbial translocation from the gastrointestinal tract into the systemic circulation. In 2021 and 2022, these hypotheses were validated and SARS-CoV-2-induced cellular senescence as well as microbial translocation were documented in both acute SARS-CoV-2 infection, long COVID, and ME/CFS, connecting intestinal barrier dysfunction to disabling fatigue and specific infectious events. The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID. To accomplish this goal, we examine the role of intestinal and blood–brain barriers in long COVID and other illnesses typified by chronic fatigue, with a special emphasis on commensal microbes functioning as viral reservoirs. Furthermore, we discuss the role of SARS-CoV-2/Mycoplasma coinfection in dysfunctional efferocytosis, emphasizing some potential novel treatment strategies, including the use of senotherapeutic drugs, HMGB1 inhibitors, Toll-like receptor 4 (TLR4) blockers, and membrane lipid replacement.

A rational strategy for the maintenance of antiviral immunity to new SARS-CoV-2 strains

New variants of SARS-CoV-2 such as Omicron BA.2, BA.4/5, BA.2.12.1 and BA 2.75 are characterized by higher infectivity and the ability to escape virus-neutralizing antibodies against previous coronavirus variants. The S-trimer of BA.2 and its phylogenetic derivatives are characterized by a predominant Up-conformation, which facilitates the interaction with ACE2 on target cells and promotes the resistance to neutralizing antibodies. The immunity acquired from the infection with earlier strains is non-sterile for both early and later strains; the booster systemic immunization does not significantly affect the effectiveness of antiviral immunity, and its feasibility is currently being questioned. Studies of the mucosal immune response have shown that intranasal immunization with adenovirus vaccines provides more pronounced protective immunity than systemic reimmunization does. A promising approach is the creation of multivalent inhaled next generation vaccines containing immunoadjuvants that activate B- and T-cell mucosal immunity. Currently, a large number of intranasal vaccines are undergoing phase I/II trials, while the preclinical and preliminary clinical results indicate that this method of vaccination provides a better mucosal immune response at the entry site of the virus than systemic immunization does. This strategy may provide a long-term immune protection against the currently existing and yet unknown new strains of SARS-CoV-2.

COVID-19, vaccines and deficiency of ACE2 and other angiotensinases. Closing the loop on the "Spike effect"

The role of a dysregulated renin-angiotensin system (RAS) in the pathogenesis of COVID-19 is well recognized. The imbalance between angiotensin II (Ang II) and Angiotensin1-7 (Ang1,7) caused by the interaction between SARS-CoV-2 and the angiotensin converting enzyme 2 (ACE2) receptors exerts a pivotal role on the clinical picture and outcome of COVID-19. ACE2 receptors are not the exclusive angiotensinases in nature. Other angiotensinases (PRCP, and POP) have the potential to limit the detrimental effects of the interactions between ACE2 and the Spike proteins. In the cardiovascular disease continuum, ACE2 activity tends to decrease, and POP/PRCP activity to increase, from the health status to advanced deterioration of the cardiovascular system. The failure of the counter-regulatory RAS axis during the acute phase of COVID-19 is characterized by a decrease of ACE2 expression coupled to unchanged activity of other angiotensinases, therefore failing to limit the accumulation of Ang II. COVID-19 vaccines increase the endogenous synthesis of SARS-CoV-2 spike proteins. Once synthetized, the free-floating spike proteins circulate in the blood, interact with ACE2 receptors and resemble the pathological features of SARS-CoV-2 ("Spike effect" of COVID-19 vaccines). It has been noted that an increased catalytic activity of POP/PRCP is typical in elderly individuals with comorbidities or previous cardiovascular events, but not in younger people. Thus, the adverse reactions to COVID-19 vaccination associated with Ang II accumulation are generally more common in younger and healthy subjects. Understanding the relationships between different mechanisms of Ang II cleavage and accumulation offers the opportunity to close the pathophysiological loop between the risk of progression to severe forms of COVID-19 and the potential adverse events of vaccination.

A raising dawn of pentoxifylline in management of inflammatory disorders in Covid-19

The existing pandemic viral infection caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) leads to coronavirus disease 2019 (Covid-19). SARS-CoV-2 exploits angiotensin-converting enzyme 2 (ACE2) as an entry-point into affected cells and down-regulation of ACE2 by this virus triggers the release of pro-inflammatory cytokines and up-regulation of angiotensin II. These changes may lead to hypercytokinemia and the development of cytokine storm with the development of acute lung injury and acute respiratory distress syndrome. Different repurposed had been in use in the management of Covid-19, one of these agents is pentoxifylline (PTX) which has anti-inflammatory and antioxidant properties. Therefore, the objective of the present mini-review is to highlight the potential role of PTX in Covid-19 regarding its anti-inflammatory and antioxidant effects. PTX is a non-selective phosphodiesterase inhibitor that increases intracellular cyclic adenosine monophosphate which stimulates protein kinase A and inhibits leukotriene and tumor necrosis factor. PTX has antiviral, anti-inflammatory and immunomodulatory effects, thus it may attenuate SARS-CoV-2-induced hyperinflammation and related complications. As well, PTX can reduce hyper-viscosity and coagulopathy in Covid-19 through increasing red blood cell deformability and inhibition of platelet aggregations. In conclusion, PTX is a non-selective phosphodiesterase drug, that has anti-inflammatory and antioxidant effects thereby can reduce SARS-CoV-2 infection-hyperinflammation and oxidative stress. Besides, PTX improves red blood cells (RBCs) deformability and reduces blood viscosity so can mitigate Covid-19-induced hyper-viscosity and RBCs hyper-aggregation which is linked with the development of coagulopathy. Taken together, PTX seems to be an effective agent against Covid-19 severity.

Impact of SARS-CoV-2 on Host Factors Involved in Mental Disorders

COVID-19, caused by SARS-CoV-2, is a systemic illness due to its multiorgan effects in patients. The disease has a detrimental impact on respiratory and cardiovascular systems. One early symptom of infection is anosmia or lack of smell; this implicates the involvement of the olfactory bulb in COVID-19 disease and provides a route into the central nervous system. However, little is known about how SARS-CoV-2 affects neurological or psychological symptoms. SARS-CoV-2 exploits host receptors that converge on pathways that impact psychological symptoms. This systemic review discusses the ways involved by coronavirus infection and their impact on mental health disorders. We begin by briefly introducing the history of coronaviruses, followed by an overview of the essential proteins to viral entry. Then, we discuss the downstream effects of viral entry on host proteins. Finally, we review the literature on host factors that are known to play critical roles in neuropsychiatric symptoms and mental diseases and discuss how COVID-19 could impact mental health globally. Our review details the host factors and pathways involved in the cellular mechanisms, such as systemic inflammation, that play a significant role in the development of neuropsychological symptoms stemming from COVID-19 infection.

Functional ACE2 deficiency leading to angiotensin imbalance in the pathophysiology of COVID-19

SARS-CoV-2, the virus responsible for COVID-19, uses angiotensin converting enzyme 2 (ACE2) as its primary cell-surface receptor. ACE2 is a key enzyme in the counter-regulatory pathway of the broader renin-angiotensin system (RAS) that has been implicated in a broad array of human pathology. The RAS is composed of two competing pathways that work in opposition to each other: the "conventional" arm involving angiotensin converting enzyme (ACE) generating angiotensin-2 and the more recently identified ACE2 pathway that generates angiotensin (1-7). Following the original SARS pandemic, additional studies suggested that coronaviral binding to ACE2 resulted in downregulation of the membrane-bound enzyme. Given the similarities between the two viruses, many have posited a similar process with SARS-CoV-2. Proponents of this ACE2 deficiency model argue that downregulation of ACE2 limits its enzymatic function, thereby skewing the delicate balance between the two competing arms of the RAS. In this review we critically examine this model. The available data remain incomplete but are consistent with the possibility that the broad multisystem dysfunction of COVID-19 is due in large part to functional ACE2 deficiency leading to angiotensin imbalance with consequent immune dysregulation and endothelial cell dysfunction.

Inhibitory Immune Checkpoint Receptors and Ligands as Prognostic Biomarkers in COVID-19 Patients

Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2. During T-cell activation, the immune system uses different checkpoint pathways to maintain co-inhibitory and co-stimulatory signals. In COVID-19, expression of immune checkpoints (ICs) is one of the most important manifestations, in addition to lymphopenia and inflammatory cytokines, contributing to worse clinical outcomes. There is a controversy whether upregulation of ICs in COVID-19 patients might lead to T-cell exhaustion or activation. This review summarizes the available studies that investigated IC receptors and ligands in COVID-19 patients, as well as their effect on T-cell function. Several IC receptors and ligands, including CTLA-4, BTLA, TIM-3, VISTA, LAG-3, TIGIT, PD-1, CD160, 2B4, NKG2A, Galectin-9, Galectin-3, PD-L1, PD-L2, LSECtin, and CD112, were upregulated in COVID-19 patients. Based on the available studies, there is a possible relationship between disease severity and increased expression of IC receptors and ligands. Overall, the upregulation of some ICs could be used as a prognostic biomarker for disease severity.

Jeopardy of COVID-19: Rechecking the Perks of Phytotherapeutic Interventions

The novel coronavirus disease (COVID-19), the reason for worldwide pandemic, has already masked around 220 countries globally. This disease is induced by Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2). Arising environmental stress, increase in the oxidative stress level, weak immunity and lack of nutrition deteriorates the clinical status of the infected patients. Though several researches are at its peak for understanding and bringing forward effective therapeutics, yet there is no promising solution treating this disease directly. Medicinal plants and their active metabolites have always been promising in treating many clinical complications since time immemorial. Mother nature provides vivid chemical structures, which act multi-dimensionally all alone or synergistically in mitigating several diseases. Their unique antioxidant and anti-inflammatory activity with least side effects have made them more effective candidate for pharmacological studies. These medicinal plants inhibit attachment, encapsulation and replication of COVID-19 viruses by targeting various signaling molecules such as angiotensin converting enzyme-2, transmembrane serine protease 2, spike glycoprotein, main protease etc. This property is re-examined and its potency is now used to improve the existing global health crisis. This review is an attempt to focus various antiviral activities of various noteworthy medicinal plants. Moreover, its implications as prophylactic or preventive in various secondary complications including neurological, cardiovascular, acute kidney disease, liver disease are also pinpointed in the present review. This knowledge will help emphasis on the therapeutic developments for this novel coronavirus where it can be used as alone or in combination with the repositioned drugs to combat COVID-19.

PTSD as an Endothelial Disease: Insights From COVID-19

SARS-CoV-2 virus, the etiologic agent of COVID-19, has affected almost every aspect of human life, precipitating stress-related pathology in vulnerable individuals. As the prevalence rate of posttraumatic stress disorder in pandemic survivors exceeds that of the general and special populations, the virus may predispose to this disorder by directly interfering with the stress-processing pathways. The SARS-CoV-2 interactome has identified several antigens that may disrupt the blood-brain-barrier by inducing premature senescence in many cell types, including the cerebral endothelial cells. This enables the stress molecules, including angiotensin II, endothelin-1 and plasminogen activator inhibitor 1, to aberrantly activate the amygdala, hippocampus, and medial prefrontal cortex, increasing the vulnerability to stress related disorders. This is supported by observing the beneficial effects of angiotensin receptor blockers and angiotensin converting enzyme inhibitors in both posttraumatic stress disorder and SARS-CoV-2 critical illness. In this narrative review, we take a closer look at the virus-host dialog and its impact on the renin-angiotensin system, mitochondrial fitness, and brain-derived neurotrophic factor. We discuss the role of furin cleaving site, the fibrinolytic system, and Sigma-1 receptor in the pathogenesis of psychological trauma. In other words, learning from the virus, clarify the molecular underpinnings of stress related disorders, and design better therapies for these conditions. In this context, we emphasize new potential treatments, including furin and bromodomains inhibitors.

Similarities between COVID-19 and systemic sclerosis early vasculopathy: A "viral" challenge for future research in scleroderma

OBJECTIVE

To review similarities between COVID-19 and systemic sclerosis (SSc) early vasculopathy to provide novel insights into both diseases.

METHODS

A narrative review of the literature supplemented with expert opinion.

RESULTS

There is clear evidence that the endothelium is at the centre stage in SSc and COVID-19, with endothelial cell activation/injury and dysfunction creating the crucial evolving step in the pathogenesis of both diseases. The angiotensin system has also been implicated in the early stages of both COVID-19 and SSc. Autoptic studies provide novel insights into the effects of SARS-CoV-2 on the endothelium. Normal endothelium and endothelial dysfunction in COVID-19 and SSc are discussed. It is debated whether SARS-CoV-2 infection triggers autoimmunity with production of autoantibodies which is of mechanistic interest because other viral illnesses are potentially involved in endothelial dysfunction and in SSc pathogenesis.

CONCLUSION

COVID-19 is due to a direct assault of SARS-CoV-2 on the vascular system as an acute infection, whereas SSc remains a chronic/sub-acute autoimmune disease of largely unknown etiology Further study and exploration of the SARS-CoV-2 pathogenic mechanisms might provide further useful milestones in the understanding of the early SSc pathogenesis.

COVID-19, ferrosenescence and neurodegeneration, a mini-review

Exacerbation of cognitive, motor and nonmotor symptoms have been described in critically ill COVID-19 patients, indicating that, like prior pandemics, neurodegenerative sequelae may mark the aftermath of this viral infection. Moreover, SARS-CoV-2, the causative agent of COVID-19 disease, was associated with hyperferritinemia and unfavorable prognosis in older individuals, suggesting virus-induced ferrosenescence. We have previously defined ferrosenescence as an iron-associated disruption of both the human genome and its repair mechanisms, leading to premature cellular senescence and neurodegeneration. As viruses replicate more efficiently in iron-rich senescent cells, they may have developed the ability to induce this phenotype in host tissues, predisposing to both immune dysfunction and neurodegenerative disorders. In this mini-review, we summarize what is known about the SARS-CoV-2-induced cellular senescence and iron dysmetabolism. We also take a closer look at immunotherapy with natural killer cells, angiotensin II receptor blockers ("sartans"), iron chelators and dipeptidyl peptidase 4 inhibitors ("gliptins") as adjunct treatments for both COVID-19 and its neurodegenerative complications.

ACE2 Down-Regulation May Act as a Transient Molecular Disease Causing RAAS Dysregulation and Tissue Damage in the Microcirculatory Environment Among COVID-19 Patients

Severe acute respiratory syndrome coronavirus 2, the etiologic agent of coronavirus disease 2019 (COVID-19) and the cause of the current pandemic, produces multiform manifestations throughout the body, causing indiscriminate damage to multiple organ systems, particularly the lungs, heart, brain, kidney, and vasculature. The aim of this review is to provide a new assessment of the data already available for COVID-19, exploring it as a transient molecular disease that causes negative regulation of angiotensin-converting enzyme 2, and consequently, deregulates the renin-angiotensin-aldosterone system, promoting important changes in the microcirculatory environment. Another goal of the article is to show how these microcirculatory changes may be responsible for the wide variety of injury mechanisms observed in different organs in this disease. The new concept of COVID-19 provides a unifying pathophysiological picture of this infection and offers fresh insights for a rational treatment strategy to combat this ongoing pandemic.

Endothelial Senescence and Chronic Fatigue Syndrome, a COVID-19 Based Hypothesis

Myalgic encephalomyelitis/chronic fatigue syndrome is a serious illness of unknown etiology, characterized by debilitating exhaustion, memory impairment, pain and sleep abnormalities. Viral infections are believed to initiate the pathogenesis of this syndrome although the definite proof remains elusive. With the unfolding of COVID-19 pandemic, the interest in this condition has resurfaced as excessive tiredness, a major complaint of patients infected with the SARS-CoV-2 virus, often lingers for a long time, resulting in disability, and poor life quality. In a previous article, we hypothesized that COVID-19-upregulated angiotensin II triggered premature endothelial cell senescence, disrupting the intestinal and blood brain barriers. Here, we hypothesize further that post-viral sequelae, including myalgic encephalomyelitis/chronic fatigue syndrome, are promoted by the gut microbes or toxin translocation from the gastrointestinal tract into other tissues, including the brain. This model is supported by the SARS-CoV-2 interaction with host proteins and bacterial lipopolysaccharide. Conversely, targeting microbial translocation and cellular senescence may ameliorate the symptoms of this disabling illness.

SARS-CoV-2/ACE2 Interaction Suppresses IRAK-M Expression and Promotes Pro-Inflammatory Cytokine Production in Macrophages

The major cause of death in SARS-CoV-2 infected patients is due to de-regulation of the innate immune system and development of cytokine storm. SARS-CoV-2 infects multiple cell types in the lung, including macrophages, by engagement of its spike (S) protein on angiotensin converting enzyme 2 (ACE2) receptor. ACE2 receptor initiates signals in macrophages that modulate their activation, including production of cytokines and chemokines. IL-1R-associated kinase (IRAK)-M is a central regulator of inflammatory responses regulating the magnitude of TLR responsiveness. Aim of the work was to investigate whether SARS-CoV-2 S protein-initiated signals modulate pro-inflammatory cytokine production in macrophages. For this purpose, we treated PMA-differentiated THP-1 human macrophages with SARS-CoV-2 S protein and measured the induction of inflammatory mediators including IL6, TNFα, IL8, CXCL5, and MIP1a. The results showed that SARS-CoV-2 S protein induced IL6, MIP1a and TNFα mRNA expression, while it had no effect on IL8 and CXCL5 mRNA levels. We further examined whether SARS-CoV-2 S protein altered the responsiveness of macrophages to TLR signals. Treatment of LPS-activated macrophages with SARS-CoV-2 S protein augmented IL6 and MIP1a mRNA, an effect that was evident at the protein level only for IL6. Similarly, treatment of PAM3csk4 stimulated macrophages with SARS-CoV-2 S protein resulted in increased mRNA of IL6, while TNFα and MIP1a were unaffected. The results were confirmed in primary human peripheral monocytic cells (PBMCs) and isolated CD14+ monocytes. Macrophage responsiveness to TLR ligands is regulated by IRAK-M, an inactive IRAK kinase isoform. Indeed, we found that SARS-CoV-2 S protein suppressed IRAK-M mRNA and protein expression both in THP1 macrophages and primary human PBMCs and CD14+ monocytes. Engagement of SARS-CoV-2 S protein with ACE2 results in internalization of ACE2 and suppression of its activity. Activation of ACE2 has been previously shown to induce anti-inflammatory responses in macrophages. Treatment of macrophages with the ACE2 activator DIZE suppressed the pro-inflammatory action of SARS-CoV-2. Our results demonstrated that SARS-CoV-2/ACE2 interaction rendered macrophages hyper-responsive to TLR signals, suppressed IRAK-M and promoted pro-inflammatory cytokine expression. Thus, activation of ACE2 may be a potential anti-inflammatory therapeutic strategy to eliminate the development of cytokine storm observed in COVID-19 patients.

Efficacy of Serum Angiotensin II Levels in Prognosis of Patients With Coronavirus Disease 2019

OBJECTIVES

We aimed to determine serum angiotensin II levels in patients with coronavirus disease 2019 infection and to investigate the effect of these levels on the prognosis of the disease.

DESIGN

The study was planned prospectively and observationally.

SETTING

The study was conducted in a tertiary university hospital.

PATIENTS

Coronavirus disease 2019 patients older than 18 years old, polymerase chain reaction test positive, with signs of pneumonia on tomography, and hospitalized were included in the study. ICU need, development of acute respiratory distress syndrome, and in-hospital mortality were considered as primary endpoints.

INTERVENTIONS

Blood samples were taken from patients three times for angiotensin II levels.

MEASUREMENTS AND MAIN RESULTS

Angiotensin II levels were studied by enzyme-linked immunosorbent assay method. The SPSS 24.0 program (Statistics Program for Social Scientists, SPSS, Chicago, IL) was used to analyze the data. A total of 112 patients were included in the study, of which 63.4% of the patients were men. The serum angiotensin II levels were statistically significantly lower in the patients with coronavirus disease 2019 compared with the healthy control group (p < 0.001). There was no statistical significance between the serum angiotensin II levels measured at three different times (p > 0.05). The serum angiotensin II levels of the patients with acute respiratory distress syndrome were found to be statistically significantly lower than those without acute respiratory distress syndrome in three samples collected at different clinical periods (p < 0.05). The angiotensin II levels of the patients who required admission to the ICU at all three times of blood sample collection were found to be statistically significantly lower than those who did not (p < 0.05). Although the serum angiotensin II levels of the patients who died were low, there was no statistically significant difference in mortality at all three times (p > 0.05).

CONCLUSIONS

The serum angiotensin II levels decrease significantly in patients with coronavirus disease 2019, and this decrease is correlated with lung damage.

Immunological Aspects of SARS-CoV-2 Infection and the Putative Beneficial Role of Vitamin-D

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is still an ongoing global health crisis. Immediately after the inhalation of SARS-CoV-2 viral particles, alveolar type II epithelial cells harbor and initiate local innate immunity. These particles can infect circulating macrophages, which then present the coronavirus antigens to T cells. Subsequently, the activation and differentiation of various types of T cells, as well as uncontrollable cytokine release (also known as cytokine storms), result in tissue destruction and amplification of the immune response. Vitamin D enhances the innate immunity required for combating COVID-19 by activating toll-like receptor 2. It also enhances antimicrobial peptide synthesis, such as through the promotion of the expression and secretion of cathelicidin and β-defensin; promotes autophagy through autophagosome formation; and increases the synthesis of lysosomal degradation enzymes within macrophages. Regarding adaptive immunity, vitamin D enhances CD4+ T cells, suppresses T helper 17 cells, and promotes the production of virus-specific antibodies by activating T cell-dependent B cells. Moreover, vitamin D attenuates the release of pro-inflammatory cytokines by CD4+ T cells through nuclear factor κB signaling, thereby inhibiting the development of a cytokine storm. SARS-CoV-2 enters cells after its spike proteins are bound to angiotensin-converting enzyme 2 (ACE2) receptors. Vitamin D increases the bioavailability and expression of ACE2, which may be responsible for trapping and inactivating the virus. Activation of the renin-angiotensin-aldosterone system (RAS) is responsible for tissue destruction, inflammation, and organ failure related to SARS-CoV-2. Vitamin D inhibits renin expression and serves as a negative RAS regulator. In conclusion, vitamin D defends the body against SARS-CoV-2 through a novel complex mechanism that operates through interactions between the activation of both innate and adaptive immunity, ACE2 expression, and inhibition of the RAS system. Multiple observation studies have shown that serum concentrations of 25 hydroxyvitamin D are inversely correlated with the incidence or severity of COVID-19. The evidence gathered thus far, generally meets Hill's causality criteria in a biological system, although experimental verification is not sufficient. We speculated that adequate vitamin D supplementation may be essential for mitigating the progression and severity of COVID-19. Future studies are warranted to determine the dosage and effectiveness of vitamin D supplementation among different populations of individuals with COVID-19.

Possible Benefit of Angiotensin II Receptor Blockers in COVID-19 Patients: A Case Series

Introduction

Dysfunction in the renin-angiotensin-aldosterone system (RAAS) has been observed in patients with coronavirus disease 2019 (COVID-19). It is presumed that the effect of reducing interleukin-6 (IL-6) levels by angiotensin II receptor blockers (ARBs) by RAAS modulation. We investigated changes in angiotensin II and IL-6 levels in four COVID-19 patients treated with ARBs. Case Presentation. Cases 1 and 2 were who had not received ARBs before and were newly administered ARBs. Case 3 restarted ARBs after discontinuation for 7 days, and case 4 received an increased dose of ARBs. The mean in angiotensin II levels (607.5 pg/mL, range: 488–850 pg/mL, reference range < 100 pg/mL), C-reactive protein (CRP) (10.58 mg/dL, range 4.45-18.05 mg/dL), and IL-6 (55.78 pg/mL, range: 12.86–144.82 pg/mL, reference range < 7 pg/mL) was observed at the admission in all patients. Upon clinical improvement, the mean decrease in CRP (1.02 mg/dL, range 0.06-3.78 mg/dL) and IL-6 (5.63 pg/mL, range 0.17-20.87 pg/mL) was observed in all patients. Conversely, angiotensin II levels gradually increased.

Conclusion

This report supports the potential benefit of ARBs to improve the clinical outcomes of COVID-19 patients by controlling RAAS dysfunction.

Endothelium Infection and Dysregulation by SARS-CoV-2: Evidence and Caveats in COVID-19

The ongoing pandemic of coronavirus disease 2019 (COVID-19) caused by the acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) poses a persistent threat to global public health. Although primarily a respiratory illness, extrapulmonary manifestations of COVID-19 include gastrointestinal, cardiovascular, renal and neurological diseases. Recent studies suggest that dysfunction of the endothelium during COVID-19 may exacerbate these deleterious events by inciting inflammatory and microvascular thrombotic processes. Although controversial, there is evidence that SARS-CoV-2 may infect endothelial cells by binding to the angiotensin-converting enzyme 2 (ACE2) cellular receptor using the viral Spike protein. In this review, we explore current insights into the relationship between SARS-CoV-2 infection, endothelial dysfunction due to ACE2 downregulation, and deleterious pulmonary and extra-pulmonary immunothrombotic complications in severe COVID-19. We also discuss preclinical and clinical development of therapeutic agents targeting SARS-CoV-2-mediated endothelial dysfunction. Finally, we present evidence of SARS-CoV-2 replication in primary human lung and cardiac microvascular endothelial cells. Accordingly, in striving to understand the parameters that lead to severe disease in COVID-19 patients, it is important to consider how direct infection of endothelial cells by SARS-CoV-2 may contribute to this process.

Novel Evidence of Acute Kidney Injury in COVID-19

The coronavirus 2019 (COVID-19) pandemic has caused a huge impact on health and economic issues. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes cellular damage by entry mediated by the angiotensin-converting enzyme 2 of the host cells and its conjugation with spike proteins of SARS-CoV-2. Beyond airway infection and acute respiratory distress syndrome, acute kidney injury is common in SARS-CoV-2-associated infection, and acute kidney injury (AKI) is predictive to multiorgan dysfunction in SARS-CoV-2 infection. Beyond the cytokine storm and hemodynamic instability, SARS-CoV-2 might directly induce kidney injury and cause histopathologic characteristics, including acute tubular necrosis, podocytopathy and microangiopathy. The expression of apparatus mediating SARS-CoV-2 entry, including angiotensin-converting enzyme 2, transmembrane protease serine 2 (TMPRSS2) and a disintegrin and metalloprotease 17 (ADAM17), within the renal tubular cells is highly associated with acute kidney injury mediated by SARS-CoV-2. Both entry from the luminal and basolateral sides of the renal tubular cells are the possible routes for COVID-19, and the microthrombi associated with severe sepsis and the dysregulated renin-angiotensin-aldosterone system worsen further renal injury in SARS-CoV-2-associated AKI. In the podocytes of the glomerulus, injured podocyte expressed CD147, which mediated the entry of SARS-CoV-2 and worsen further foot process effacement, which would worsen proteinuria, and the chronic hazard induced by SARS-CoV-2-mediated kidney injury is still unknown. Therefore, the aim of the review is to summarize current evidence on SARS-CoV-2-associated AKI and the possible pathogenesis directly by SARS-CoV-2.