Nicotine modulates the renin-angiotensin system of cultured neurons and glial cells from cardiovascular brain areas of Wistar Kyoto and spontaneously hypertensive rats

The Interplay of HIV and Long COVID in Sub-Saharan Africa: Mechanisms of Endothelial Dysfunction

PURPOSE OF REVIEW

Long COVID affects approximately 5 million people in Africa. This disease is characterized by persistent symptoms or new onset of symptoms after an acute SARS-CoV-2 infection. Specifically, the most common symptoms include a range of cardiovascular problems such as chest pain, orthostatic intolerance, tachycardia, syncope, and uncontrolled hypertension. Importantly, these conditions appear to have endothelial dysfunction as the common denominator, which is often due to impaired nitric oxide (NO) mechanisms. This review discusses the role of mechanisms contributing to endothelial dysfunction in Long COVID, particularly in people living with HIV.

RECENT FINDINGS

Recent studies have reported that increased inflammation and oxidative stress, frequently observed in Long COVID, may contribute to NO dysfunction, ultimately leading to decreased vascular reactivity. These mechanisms have also been reported in people living with HIV. In regions like Africa, where HIV infection is still a major public health challenge with a prevalence of approximately 26 million people in 2022. Specifically, endothelial dysfunction has been reported as a major mechanism that appears to contribute to cardiovascular diseases and the intersection with Long COVID mechanisms is of particular concern. Further, it is well established that this population is more likely to develop Long COVID following infection with SARS-CoV-2. Therefore, concomitant infection with SARS-CoV-2 may lead to accelerated cardiovascular disease. We outline the details of the worsening health problems caused by Long COVID, which exacerbate pre-existing conditions such as endothelial dysfunction. The overlapping mechanisms of HIV and SARS-CoV-2, particularly the prolonged inflammatory response and chronic hypoxia, may increase susceptibility to Long COVID. Addressing these overlapping health issues is critical as it provides clinical entry points for interventions that could improve and enhance outcomes and quality of life for those affected by both HIV and Long COVID in the region.

Structural Features Influencing the Bioactive Conformation of Angiotensin II and Angiotensin A: Relationship between Receptor Desensitization, Addiction, and the Blood-Brain Barrier

The N-terminal portion of the octapeptide angiotensin II (DRVYIHPF; AngII), a vasopressor peptide that favorably binds to, and activates, AngII type 1 receptor (AT1R), has an important role in maintaining bioactive conformation. It involves all three charged groups, namely (i) the N-terminal amino group cation, (ii) the Asp sidechain anion and (iii) the Arg guanidino cation. Neutralization of any one of these three charged groups results in a substantial reduction (<5%) in bioactivity, implicating a specialized function for this cluster. In contrast, angiotensin A (ARVYIHPF; AngA) has reduced bioactivity at AT1R; however, replacement of Asp in AngII with sarcosine (N-methyl-glycine) not only restores bioactivity but increases the activity of agonist, antagonist, and inverse agonist analogues. A bend produced at the N-terminus by the introduction of the secondary amino acid sarcosine is thought to realign the functional groups that chaperone the C-terminal portion of AngII, allowing transfer of the negative charge originating at the C-terminus to be transferred to the Tyr hydroxyl-forming tyrosinate anion, which is required to activate the receptor and desensitizes the receptor (tachyphylaxis). Peptide (sarilesin) and nonpeptide (sartans) moieties, which are long-acting inverse agonists, appear to desensitize the receptor by a mechanism analogous to tachyphylaxis. Sartans/bisartans were found to bind to alpha adrenergic receptors resulting in structure-dependent desensitization or resensitization. These considerations have provided information on the mechanisms of receptor desensitization/tolerance and insights into possible avenues for treating addiction. In this regard sartans, which appear to cross the blood-brain barrier more readily than bisartans, are the preferred drug candidates.

Associations of active and passive tobacco exposure with elevated blood pressure in Korean adolescents

OBJECTIVES

To test the hypothesis that tobacco exposure is associated with elevated blood pressure (EBP) in Korean adolescents, and that the association is dose dependent.

METHODS

This cross-sectional study used data from the 2011-2020 Korea National Health and Nutrition Survey (KNHANES). Subjects were eligible if they were 13-18 years at the time of participation in KNHANES. Tobacco exposure was defined by urine cotinine level. The main outcomes were EBP and hypertension. Statistical analyses were conducted using SAS version 9.4 with appropriate sampling weights to account for the complex survey design, stratification, and cluster variable.

RESULTS

A total of 2,518 adolescents was included in the analysis, representing 2.5 million Korean adolescents. The mean± standard deviation participant age was 15.3±1.7 years, and 55.3% were male. The number of participants with active tobacco smoke exposure was 283 (11.2%), passive tobacco smoke exposure was 145 (5.8%), and no smoke exposure was 2,090 (83.0%). Analysis of the 2,518 urine-cotinine-verified participants showed that tobacco smoke exposure had a significant effect on EBP: with an odds of elevated blood pressure of 3.00 (95% confidence interval [CI], 1.14 to 7.89). The odds of hypertension were 3.61 (95% CI, 1.13 to 11.49) in the active smoking group compared with the no tobacco exposure group after adjustment for potential confounders.

CONCLUSIONS

It is necessary to present a range of public health plans to reduce tobacco exposure that affects adolescents' blood pressure, and further research with a larger number of participants using urine cotinine as a biomarker is needed.

Impact of COVID-19 on Anxiety and Depression - Biopsychosocial Factors

Anxiety and depression are prevalent mental disorders around the world. The etiology of both diseases is multifactorial, involving biological and psychological issues. The COVID-19 pandemic settled in 2020 and culminated in several changes in the routine of individuals around the world, affecting mental health. People infected with COVID-19 are at greater risk of developing anxiety and depression, and individuals previously affected by these disorders have worsened the condition. In addition, individuals diagnosed with anxiety or depression before being affected by COVID-19 developed the severe illness at higher rates than individuals without mental disorders. This harmful cycle involves several mechanisms, including systemic hyper-inflammation and neuroinflammation. Furthermore, the context of the pandemic and some previous psychosocial factors can aggravate or trigger anxiety and depression. Disorders are also risks for a more severe picture of COVID-19. This review discusses research on a scientific basis, which brings evidence on biopsychosocial factors from COVID-19 and the context of the pandemic involved in anxiety and depression disorders.

Interplay between the renin angiotensin system and oxidative stress contributes to alcohol addiction by stimulating dopamine accumulation in the mesolimbic pathway

The brain renin-angiotensin system (RAS) has recently been implicated in the development of substance abuse and addiction. However, the integrative roles of the two counter-regulating RAS arms, including the ACE1/Ang II/AT1R axis and the ACE2/Ang(1-7)/MasR axis, in alcohol addiction remain unclear. Using the 20% ethanol intermittent-access two-bottle-choice (IA2BC) paradigm, we observed significant alcohol preference and addictive behaviors in rats. Additionally, we observed significant disruption in the RAS and redox homeostasis in the ventral tegmental area (VTA), as indicated by upregulation of ACE1 activities, Ang II levels, AT1R expression, and glutathione disulfide contents, as well as downregulation of ACE2 activities, Ang(1-7) levels, MasR expression and glutathione content. Moreover, dopamine accumulated in the VTA and nucleus accumbens of IA2BC rats. Intra-VTA infusion of the antioxidant tempol substantially attenuated RAS imbalance and addictive behaviors. Intra-VTA infusion of the ACE1 inhibitor captopril significantly reduced oxidative stress, alcohol preference, addictive behaviors, and dopamine accumulation, whereas intra-VTA infusion of the ACE2 inhibitor MLN4760 had the opposite effects. The anti-addictive effects of the ACE2/Ang(1-7)/MasR axis were further observed using intra-VTA infusion of Ang(1-7) and a MasR-specific antagonist A779. Therefore, our findings suggest that excessive alcohol intake causes RAS imbalance via oxidative stress, and that a dysregulated RAS in the VTA contributes to alcohol addiction by stimulating oxidative stress and dopaminergic neurotransmission. Breaking the vicious cycle of RAS imbalance and oxidative stress using brain-permeable antioxidants, ACE1 inhibitors, ACE2 activators, or Ang(1-7) mimetics thus represents a promising strategy for combating alcohol addiction.

The Neuropathological Impacts of COVID-19: Challenges and Alternative Treatment Options for Alzheimer's Like Brain Changes on Severely SARS-CoV-2 Infected Patients

Recently, some researchers claimed neuropathological changes lead to Alzheimer's-like brains after severe infection of SARS-CoV-2. Several mechanisms have been postulated on how SARS-CoV-2 neurological damage leads to Alzheimer's disease (AD) development. Neurobiochemical changes during infection may significantly induce Alzheimer's disease in severely COVID-19 infected people. The immune system is also compromised while infected by this novel coronavirus. However, recent studies are insufficient to conclude the relationship between Alzheimer's disease and COVID-19. This review demonstrates the possible pathways of neuropathological changes induced by the SARS-CoV-2 virus in AD patients or leading to AD in COVID-19 patients. Therefore, this study delineates the challenges for COVID-19 infected AD patients and the mechanism of actions of natural compounds and alternative treatments to overcome those. Furthermore, animal studies and a large cohort of COVID-19 survivors who showed neuroinflammation and neurological changes may augment the research to discover the relationship between Alzheimer's disease and COVID-19.

Smoking enhances the expression of angiotensin-converting enzyme 2 involved in the efficiency of severe acute respiratory syndrome coronavirus 2 infection

Smoking is one of the risk factors most closely related to the severity of coronavirus disease 2019 (COVID-19). However, the relationship between smoking history and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infectivity is unknown. In this study, we evaluated the ACE2 expression level in the lungs of current smokers, ex-smokers, and nonsmokers. The ACE2 expression level of ex-smokers who smoked cigarettes until recently (cessation period shorter than 6 months) was higher than that of nonsmokers and ex-smokers with a long history of nonsmoking (cessation period longer than 6 months). We also showed that the efficiency of SARS-CoV-2 infection was enhanced in a manner dependent on the angiotensin-converting enzyme 2 (ACE2) expression level. Using RNA-seq analysis on the lungs of smokers, we identified that the expression of inflammatory signaling genes was correlated with ACE2 expression. Notably, with increasing duration of smoking cessation among ex-smokers, not only ACE2 expression level but also the expression levels of inflammatory signaling genes decreased. These results indicated that smoking enhances the expression levels of ACE2 and inflammatory signaling genes. Our data suggest that the efficiency of SARS-CoV-2 infection is enhanced by smoking-mediated upregulation of ACE2 expression level.

Effect of heated tobacco products and traditional cigarettes on pulmonary toxicity and SARS-CoV-2-induced lung injury

Cigarette smoke (CS) significantly contributes to the development of chronic obstructive pulmonary disease (COPD). Heated tobacco products (HTPs), newly developed cigarette products, have been proposed as an alternative for safe cigarette smoking. Although it is plausible to think that replacing traditional cigarettes with HTPs would lower the risks of COPD, this notion requires confirmation by further investigations from sources independent of the tobacco industry. COPD is characterized by an ongoing inflammatory process in the lungs, and the renin-angiotensin system (RAS) has been implicated in the pathogenesis of COPD. Angiotensin-converting enzyme-2 (ACE2) functions as a negative regulator of RAS and has been suggested as a cellular receptor for the causative agent of SARS-CoV-2. It has been shown that smoking is most likely associated with the negative progression and adverse outcomes of SARS-CoV-2. In this study, we found that cigarette smoke extracts from traditional cigarettes (CSE) caused higher cytotoxicity and higher oxidative stress levels than extracts from HTPs (HTPE) in two lung cell lines (Calu-3 and Beas-2B). CSE and HTPE induced RAS activation, MAPK activation, and NF-kB inflammatory pathway activation, resulting in the production of inflammatory cytokines. Furthermore, CSE and a high dose of HTPE reduced tight junction proteins, including claudin 1, E-cadherin, and ZO-1, and disrupted lung epidermal tight junctions at the air-liquid interface (ALI). Finally, CSE and HTPE enhanced the spike protein S1-induced lung injury response. Together, these results suggest that HTPE induced similar lung pathogenesis relevant to COPD and SARS-CoV-2-induced lung injury caused by CSE.

Coagulation System Activation for Targeting of COVID-19: Insights into Anticoagulants, Vaccine-Loaded Nanoparticles, and Hypercoagulability in COVID-19 Vaccines

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as COVID-19, is currently developing into a rapidly disseminating and an overwhelming worldwide pandemic. In severe COVID-19 cases, hypercoagulability and inflammation are two crucial complications responsible for poor prognosis and mortality. In addition, coagulation system activation and inflammation overlap and produce life-threatening complications, including coagulopathy and cytokine storm, which are associated with overproduction of cytokines and activation of the immune system; they might be a lead cause of organ damage. However, patients with severe COVID-19 who received anticoagulant therapy had lower mortality, especially with elevated D-dimer or fibrin degradation products (FDP). In this regard, the discovery of natural products with anticoagulant potential may help mitigate the numerous side effects of the available synthetic drugs. This review sheds light on blood coagulation and its impact on the complication associated with COVID-19. Furthermore, the sources of natural anticoagulants, the role of nanoparticle formulation in this outbreak, and the prevalence of thrombosis with thrombocytopenia syndrome (TTS) after COVID-19 vaccines are also reviewed. These combined data provide many research ideas related to the possibility of using these anticoagulant agents as a treatment to relieve acute symptoms of COVID-19 infection.

Smoke, nicotine, opioids, and cannabinoids effects on the ACE2 protein level and possibility of COVID-19 infection: Suggesting potential preventives and therapeutics

Introduction. The coronavirus caused the pandemic COVID-19 that has an extensive influence in the world. The virus enters and infects body cells through superficial protein ACE2. Each cell possessing ACE2 is potentially vulnerable to this virus. Since the respiratory system is exposed to the environment and has ACE2, it is one of the first candidates infected by the virus. One of the considerable complications in the severe stage of COVID-19 is an intense adaptive immunological response that is detrimental to body organs. Methods. This is a review article. All relevant articles which were accessible were reviewed. Results. Some drugs of abuse may have an adverse or beneficial influence on the disease, and their simultaneity with COVID-19 is remarkable. Nicotine and cholinergic nicotinic receptor agonists seem to decrease the cell's membrane superficial ACE2 protein number; thus, they would be appropriate candidates for COVID-19 prevention and expansion. Both opioids and cannabinoids attenuate the immune system and seem to be adverse for disease incidence but can be beneficial for the severe stage of COVID19. The antitussive effect of some opioids would be advantageous. Furthermore, some opioids are substrates for ACE2 and they bind it. Therefore, they would be an appropriate candidate to design a drug covering ACE2 with a high affinity to prevent coronavirus infection. Conclusion. Some drugs, such as nicotine and opioids, may have beneficial effects on preventing or reducing COVID-19 complications.

Paradoxical effects of cigarette smoke and COPD on SARS-CoV-2 infection and disease

BACKGROUND

How cigarette smoke (CS) and chronic obstructive pulmonary disease (COPD) affect severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection and severity is controversial. We investigated the effects of COPD and CS on the expression of SARS-CoV-2 entry receptor ACE2 in vivo in COPD patients and controls and in CS-exposed mice, and the effects of CS on SARS-CoV-2 infection in human bronchial epithelial cells in vitro.

METHODS

We quantified: (1) pulmonary ACE2 protein levels by immunostaining and ELISA, and both ACE2 and/or TMPRSS2 mRNA levels by RT-qPCR in two independent human cohorts; and (2) pulmonary ACE2 protein levels by immunostaining and ELISA in C57BL/6 WT mice exposed to air or CS for up to 6 months. The effects of CS exposure on SARS-CoV-2 infection were evaluated after in vitro infection of Calu-3 cells and differentiated human bronchial epithelial cells (HBECs), respectively.

RESULTS

ACE2 protein and mRNA levels were decreased in peripheral airways from COPD patients versus controls but similar in central airways. Mice exposed to CS had decreased ACE2 protein levels in their bronchial and alveolar epithelia versus air-exposed mice. CS treatment decreased viral replication in Calu-3 cells, as determined by immunofluorescence staining for replicative double-stranded RNA (dsRNA) and western blot for viral N protein. Acute CS exposure decreased in vitro SARS-CoV-2 replication in HBECs, as determined by plaque assay and RT-qPCR.

CONCLUSIONS

ACE2 levels were decreased in both bronchial and alveolar epithelial cells from COPD patients versus controls, and from CS-exposed versus air-exposed mice. CS-pre-exposure potently inhibited SARS-CoV-2 replication in vitro. These findings urge to investigate further the controversial effects of CS and COPD on SARS-CoV-2 infection.

Mas receptor is translocated to the nucleus upon agonist stimulation in brainstem neurons from spontaneously hypertensive rats but not normotensive rats

AIMS

Activation of the angiotensin (Ang)-(1-7)/Mas receptor (R) axis protects from sympathetic overactivity. Endocytic trafficking is an essential process that regulates receptor (R) function and its ultimate cellular responses. We investigated whether the blunted responses to Ang-(1-7) in hypertensive rats are associated to an alteration in MasR trafficking.

METHODS AND RESULTS

Brainstem neurons from Wistar-Kyoto (WKY) or spontaneously hypertensive rats (SHRs) were investigated for (i) Ang-(1-7) levels and binding and MasR expression, (ii) Ang-(1-7) responses (arachidonic acid and nitric oxide release and Akt and ERK1/2 phosphorylation), and (iii) MasR trafficking. Ang-(1-7) was determined by radioimmunoassay. MasR expression and functionality were evaluated by western blot and binding assays. MasR trafficking was evaluated by immunofluorescence. Ang-(1-7) treatment induced an increase in nitric oxide and arachidonic acid release and ERK1/2 and Akt phosphorylation in WKY neurons but did not have an effect in SHR neurons. Although SHR neurons showed greater MasR expression, Ang-(1-7)-elicited responses were substantially diminished presumably due to decreased Ang-(1-7) endogenous levels concomitant with impaired binding to its receptor. Through immunocolocalization studies, we evidenced that upon Ang-(1-7) stimulation MasRs were internalized through clathrin-coated pits and caveolae into early endosomes and slowly recycled back to the plasma membrane. However, the fraction of internalized MasRs into early endosomes was larger and the fraction of MasRs recycled back to the plasma membrane was smaller in SHR than in WKY neurons. Surprisingly, in SHR neurons but not in WKY neurons, Ang-(1-7) induced MasR translocation to the nucleus. Nuclear MasR expression and Ang-(1-7) levels were significantly greater in the nuclei of Ang-(1-7)-stimulated SHR neurons, indicating that the MasR is translocated with its ligand bound to it.

CONCLUSION

MasRs display differential trafficking in brainstem neurons from SHRs, which may contribute to the impaired responses to Ang-(1-7).

Severe acute respiratory syndrome coronavirus 2 infection reaches the human nervous system: How?

Without protective and/or therapeutic agents the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection known as coronavirus disease 2019 is quickly spreading worldwide. It has surprising transmissibility potential, since it could infect all ages, gender, and human sectors. It attacks respiratory, gastrointestinal, urinary, hepatic, and endovascular systems and can reach the peripheral nervous system (PNS) and central nervous system (CNS) through known and unknown mechanisms. The reports on the neurological manifestations and complications of the SARS-CoV-2 infection are increasing exponentially. Herein, we enumerate seven candidate routes, which the mature or immature SARS-CoV-2 components could use to reach the CNS and PNS, utilizing the within-body cross talk between organs. The majority of SARS-CoV-2-infected patients suffer from some neurological manifestations (e.g., confusion, anosmia, and ageusia). It seems that although the mature virus did not reach the CNS or PNS of the majority of patients, its unassembled components and/or the accompanying immune-mediated responses may be responsible for the observed neurological symptoms. The viral particles and/or its components have been specifically documented in endothelial cells of lung, kidney, skin, and CNS. This means that the blood-endothelial barrier may be considered as the main route for SARS-CoV-2 entry into the nervous system, with the barrier disruption being more logical than barrier permeability, as evidenced by postmortem analyses.

COVID-19, COPD, and AECOPD: Immunological, Epidemiological, and Clinical Aspects

The newly identified severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) causes several heterogeneous clinical conditions collectively known as Coronavirus disease-19 (COVID-19). Older patients with significant cardiovascular conditions and chronic obstructive pulmonary disease (COPD) are predisposed to a more severe disease complicated with acute respiratory distress syndrome (ARDS), which is associated with high morbidity and mortality. COPD is associated with increased susceptibility to respiratory infections, and viruses are among the top causes of acute exacerbations of COPD (AECOPD). Thus, COVID-19 could represent the ultimate cause of AECOPD. This review will examine the pathobiological processes underlying SARS-CoV-2 infection, including the effects of cigarette smoke and COPD on the immune system and vascular endothelium, and the known effects of cigarette smoke on the onset and progression of COVID-19. We will also review the epidemiological data on COVID-19 prevalence and outcome in patients with COPD and analyze the pathobiological and clinical features of SARS-CoV-2 infection in the context of other known viral causes of AECOPD. Overall, SARS-CoV-2 shares common pathobiological and clinical features with other viral agents responsible for increased morbidity, thus representing a novel cause of AECOPD with the potential for a more long-term adverse impact. Longitudinal studies aimed at COPD patients surviving COVID-19 are needed to identify therapeutic targets for SARS-CoV2 and prevent the disease's burden in this vulnerable population.

How Does COVID-19 Affect the Neurobiology of Suicide?

PURPOSE OF REVIEW

The aim of this review was to analyze COVID-19 effect on the biological features of suicidal vulnerability and its interaction with suicide-related biological pathways. We carried out a narrative review of international publications on the interactions of COVID-19 with the biological bases of suicide.

RECENT FINDINGS

We hypothesize that SARS-CoV-2 interacts with multiple biological processes that underlie suicidal behavior, such as the renin-angiotensin system, nicotinic receptors, and central and systemic inflammation. Social distancing measures may also worsen subjective or objective social disconnection, thus increasing the risk of suicide. Interestingly, the drugs used to prevent suicide could be promising options to counteract brain damage caused by this coronavirus. SARS-CoV-2 interacts with multiple biological pathways involved in suicide and opens a new window for understanding the suicidal process. The development of suicide prevention treatments in the context of a pandemic may benefit from knowledge on these interactions.

Implications for Neuromodulation Therapy to Control Inflammation and Related Organ Dysfunction in COVID-19

COVID-19 is a syndrome that includes more than just isolated respiratory disease, as severe acute respiratory syndrome-coronavirus 2 (SARS-CoV2) also interacts with the cardiovascular, nervous, renal, and immune system at multiple levels, increasing morbidity in patients with underlying cardiometabolic conditions and inducing myocardial injury or dysfunction. Emerging evidence suggests that patients with the highest rate of morbidity and mortality following SARS-CoV2 infection have also developed a hyperinflammatory syndrome (also termed cytokine release syndrome). We lay out the potential contribution of a dysfunction in autonomic tone to the cytokine release syndrome and related multiorgan damage in COVID-19. We hypothesize that a cholinergic anti-inflammatory pathway could be targeted as a therapeutic avenue. Graphical Abstract .

Coagulation Dysfunction

CONTEXT.—

The coronavirus disease 2019 (COVID-19) is a highly contagious respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coagulation dysfunction is a hallmark in patients with COVID-19. Fulminant thrombotic complications emerge as critical issues in patients with severe COVID-19.

OBJECTIVE.—

To present a review of the literature and discuss the mechanisms of COVID-19 underlying coagulation activation and the implications for anticoagulant and thrombolytic treatment in the management of COVID-19.

DATA SOURCES.—

We performed a systemic review of scientific papers on the topic of COVID-19, available online via the PubMed NCBI, medRxiv, and Preprints as of May 15, 2020. We also shared our experience on the management of thrombotic events in patients with COVID-19.

CONCLUSIONS.—

COVID-19-associated coagulopathy ranges from mild laboratory alterations to disseminated intravascular coagulation (DIC) with a predominant phenotype of thrombotic/multiple organ failure. Characteristically, high D-dimer levels on admission and/or continuously increasing concentrations of D-dimer are associated with disease progression and poor overall survival. SARS-CoV-2 infection triggers the immune-hemostatic response. Drastic inflammatory responses including, but not limited to, cytokine storm, vasculopathy, and NETosis may contribute to an overwhelming activation of coagulation. Hypercoagulability and systemic thrombotic complications necessitate anticoagulant and thrombolytic interventions, which provide opportunities to prevent or reduce "excessive" thrombin generation while preserving "adaptive" hemostasis and bring additional benefit via their anti-inflammatory effect in the setting of COVID-19.

The Role of Smoking and Nicotine in the Transmission and Pathogenesis of COVID-19

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 virus, is turning out to be one of the most devastating global pandemics in the history of humankind. There is a shortage of effective therapeutic strategies or preventative vaccines for this disease to date. A rigorous investigation is needed for identifying and developing more effective therapeutic strategies for COVID-19. Angiotensin-converting enzyme 2 (ACE2), a crucial factor in COVID-19 pathogenesis, has been identified as a potential target for COVID-19 treatment. Smoking and vaping are potential risk factors for COVID-19 that are also shown to upregulate ACE2 expression. In this review, we have discussed the pathobiology of COVID-19 in the lungs and brain and the role of ACE2 in the transmission and pathobiology of this disease. Furthermore, we have shown possible interactions between nicotine/smoking and ACE2 in the lungs and brain, which could aggravate the transmission and pathobiology of COVID-19, resulting in a poor disease outcome. SIGNIFICANCE STATEMENT: This review addresses the present global pandemic of coronavirus disease 2019 (COVID-19) with respect to its pathobiology in the lungs and brain. It focuses on the potential negative impact of tobacco and nicotine exposure on the outcomes of this disease by interaction with the angiotensin-converting enzyme 2 receptor. It adds to the time-sensitive and critically important growing knowledge about the risk factors, transmission, pathobiology, and prognosis of COVID-19.

COVID-19 and the central nervous system

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Awareness of atypical clinical presentation of COVID patients.

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Continued sharing and publishing of case series to better understand symptoms, signs, and prognosis of patients with COVID.

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Continued studies needed to fully undertstand the long term consequences of COVID on the neurological system.

Altered COVID-19 receptor ACE2 expression in a higher risk group for cerebrovascular disease and ischemic stroke

Coronavirus disease 2019 (COVID-19) is a worldwide pandemic. It has a high transmission rate among humans, and is a threat to global public health. However, there are no effective prophylactics or therapeutics available. It is necessary to identify vulnerable and susceptible groups for adequate protection and care against this disease. Recent studies have reported that COVID-19 has angiotensin-converting enzyme 2 (ACE2) as a functional receptor, which may lead to the development of severe cerebrovascular diseases (CVD), including strokes, in patients with risk factors for CVD such as diabetes and smoking. Thus, the World Health Organization (WHO) advised caution against COVID-19 for smokers and patients with underlying clinical symptoms, including cardiovascular diseases. Here, we observed ACE2 expression in the brain of rat middle cerebral artery occlusion (MCAO) model and evaluated the effects of cigarette smoke extract (CSE) and diabetes on ACE2 expression in vessels. We showed that the levels of ACE2 expression was increased in the cortex penumbra after ischemic injuries. CSE treatment significantly elevated ACE2 expression in human brain vessels. We found that ACE2 expression was upregulated in primary cultured human blood vessels with diabetes compared to healthy controls. This study demonstrates that ACE2 expression is increased in ischemic brains and vessels exposed to diabetes or smoking, makes them vulnerable to COVID-19 infection.

Cigarette Smoke Exposure and Inflammatory Signaling Increase the Expression of the SARS-CoV-2 Receptor ACE2 in the Respiratory Tract

The factors mediating fatal SARS-CoV-2 infections are poorly understood. Here, we show that cigarette smoke causes a dose-dependent upregulation of angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 receptor, in rodent and human lungs. Using single-cell sequencing data, we demonstrate that ACE2 is expressed in a subset of secretory cells in the respiratory tract. Chronic smoke exposure triggers the expansion of this cell population and a concomitant increase in ACE2 expression. In contrast, quitting smoking decreases the abundance of these secretory cells and reduces ACE2 levels. Finally, we demonstrate that ACE2 expression is responsive to inflammatory signaling and can be upregulated by viral infections or interferon treatment. Taken together, these results may partially explain why smokers are particularly susceptible to severe SARS-CoV-2 infections. Furthermore, our work identifies ACE2 as an interferon-stimulated gene in lung cells, suggesting that SARS-CoV-2 infections could create positive feedback loops that increase ACE2 levels and facilitate viral dissemination.

Does COVID19 Infect the Brain? If So, Smokers Might Be at a Higher Risk

COVID19 is a devastating global pandemic with epicenters in China, Italy, Spain, and now the United States. While the majority of infected cases appear mild, in some cases, individuals present serious cardiorespiratory complications with possible long-term lung damage. Infected individuals report a range of symptoms from headaches to shortness of breath to taste and smell loss. To that end, less is known about how the virus may impact different organ systems. The SARS-CoV2 virus, which is responsible for COVID19, is highly similar to SARS-CoV. Both viruses have evolved an ability to enter host cells through direct interaction with the angiotensin converting enzyme (ACE) 2 protein at the surface of many cells. Published findings indicate that SARS-CoV can enter the human nervous system with evidence from both postmortem brains and detection in cerebrospinal fluid of infected individuals. Here, we consider the ability of SARS-CoV2 to enter and infect the human nervous system based on the strong expression of the ACE2 target throughout the brain. Moreover, we predict that nicotine exposure through various kinds of smoking (cigarettes, electronic cigarettes, or vape) can increase the risk for COVID19 neuroinfection based on known functional interactions between the nicotinic receptor and ACE2. We advocate for higher surveillance and analysis of neurocomplications in infected cases. SIGNIFICANCE STATEMENT: The COVID19 epidemic has spurred a global public health crisis. While many of the cases requiring hospitalization and intensive medical care center on cardiorespiratory treatment, a growing number of cases present neurological symptoms. Viral entry into the brain now appears a strong possibility with deleterious consequences and an urgent need for addressing.

Is nicotine exposure linked to cardiopulmonary vulnerability to COVID-19 in the general population?

The recent emergence of COVID‐19 has resulted in a worldwide crisis, with large populations locked down and transportation links severed. While approximately 80% of infected individuals have minimal symptoms, around 15–20% need to be hospitalized, greatly stressing global healthcare systems. As of March 10, the death rate appears to be about 3.4%, although this number is highly stratified among different populations. Here, we focus on those individuals who have been exposed to nicotine prior to their exposure to the virus. We predict that these individuals are ‘primed’ to be at higher risk because nicotine can directly impact the putative receptor for the virus (ACE2) and lead to deleterious signaling in lung epithelial cells.

Delirium in COVID-19: A case series and exploration of potential mechanisms for central nervous system involvement

INTRODUCTION

Neuropsychiatric manifestations of the coronavirus disease 2019 (COVID-19) have been described, including anosmia, ageusia, headache, paresthesia, encephalitis and encephalopathy. Little is known about the mechanisms by which the virus causes central nervous system (CNS) symptoms, and therefore little guidance is available regarding potential workup or management options.

CASES

We present a series of four consecutive cases, seen by our psychiatry consultation service over a one-week period, each of which manifested delirium as a result of infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

DISCUSSION

The four cases highlighted here all occurred in older patients with premorbid evidence of cognitive decline. Unique features seen in multiple cases included rigidity, alogia, abulia, and elevated inflammatory markers. In all four cases, a change in mental status was the presenting symptom, and three of the four cases lacked significant respiratory symptoms. In addition to discussing unique features of the cases, we discuss possible pathophysiologic explanations for COVID-19 delirium.

CONCLUSIONS

Delirium should be recognized as a potential feature of infection with SARS-CoV-2 and may be the only presenting symptom. Based on the high rates of delirium demonstrated in prior studies, hospitals should consider adding mental status changes to the list of testing criteria. Further research is needed to determine if delirium in COVID-19 represents a primary encephalopathy heralding invasion of the CNS by the virus, or a secondary encephalopathy related to systemic inflammatory response or other factors.

Nicotine and the renin-angiotensin system

Cigarette smoking is the single most important risk factor for the development of cardiovascular and pulmonary diseases (CVPD). Although cigarette smoking has been in constant decline since the 1950s, the introduction of e-cigarettes or electronic nicotine delivery systems 10 yr ago has attracted former smokers as well as a new generation of consumers. Nicotine is a highly addictive substance, and it is currently unclear whether e-cigarettes are "safer" than regular cigarettes or whether they have the potential to reverse the health benefits, notably on the cardiopulmonary system, acquired with the decline of tobacco smoking. Of great concern, nicotine inhalation devices are becoming popular among young adults and youths, emphasizing the need for awareness and further study of the potential cardiopulmonary risks of nicotine and associated products. This review focuses on the interaction between nicotine and the renin-angiotensin system (RAS), one of the most important regulatory systems on autonomic, cardiovascular, and pulmonary functions in both health and disease. The literature presented in this review strongly suggests that nicotine alters the homeostasis of the RAS by upregulating the detrimental angiotensin-converting enzyme (ACE)/angiotensin (ANG)-II/ANG II type 1 receptor axis and downregulating the compensatory ACE2/ANG-(1-7)/Mas receptor axis, contributing to the development of CVPD.

The Renin-Angiotensin-Aldosterone System in Smokers and Non-Smokers of the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study

High concentrations of renin and aldosterone are risk factors for cardiovascular diseases (CVD) which are the leading cause of morbidity and mortality worldwide. Enhanced activation of the renin-angiotensin-aldosterone system (RAAS) by cigarette smoking has been reported. The aim of our study was to analyze the effect of cigarette smoking on parameters of the RAAS in active smokers (AS) and life-time non-smokers (NS) of the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study as well as the utility of RAAS parameter for risk prediction. We determined the concentration of aldosterone, renin, angiotensin-I and angiotensin-II in participants of the LURIC study. Smoking status was assessed by a questionnaire and the measurement of plasma cotinine concentration. Parameters were log transformed before entering analyses, where appropriate. We used a multivariate Cox regression analysis to assess the effect of parameters on mortality. From the 3316 LURIC participants 777 were AS and 1178 NS. Within a median observation period of 10 years 221 (28.4 %) AS and 302 (25.6 %) NS died. After adjustment for age, gender, and the use of anti-hypertensive medication, only angiotensin-I was significantly different in AS compared to NS with an estimated marginal mean (95 % CI) of 1607 (1541-1673) ng/L and 1719 (1667-1772) ng/L, respectively. For both NS and AS renin and angiotensin-II were directly associated with mortality in the multivariate Cox regression analysis. Angiotensin-I was only associated with increased risk for mortality in NS (HR (95 % CI) of 0.69 (0.53-0.89)). We conclude that increased renin and angiotensin-II are independent predictors of mortality in AS and NS, while angiotensin-I was associated with reduced risk of death in NS only.

Potential mechanisms of hypothalamic renin-angiotensin system activation by leptin and DOCA-salt for the control of resting metabolism

The renin-angiotensin system (RAS), originally described as a circulating hormone system, is an enzymatic cascade in which the final vasoactive peptide angiotensin II (ANG) regulates cardiovascular, hydromineral, and metabolic functions. The RAS is also synthesized locally in a number of tissues including the brain, where it can act in a paracrine fashion to regulate blood pressure, thirst, fluid balance, and resting energy expenditure/resting metabolic rate (RMR). Recent studies demonstrate that ANG AT_1A receptors (Agtr1a) specifically in agouti-related peptide (AgRP) neurons of the arcuate nucleus (ARC) coordinate autonomic and energy expenditure responses to various stimuli including deoxycorticosterone acetate (DOCA)-salt, high-fat feeding, and leptin. It remains unclear, however, how these disparate stimuli converge upon and activate this specific population of AT_1A receptors in AgRP neurons. We hypothesize that these stimuli may act to stimulate local expression of the angiotensinogen (AGT) precursor for ANG, or the expression of AT_1A receptors, and thereby local activity of the RAS within the (ARC). Here we review mechanisms that may control AGT and AT_1A expression within the central nervous system, with a particular focus on mechanisms activated by steroids, dietary fat, and leptin.

Is nicotine a key player or spectator in the induction and progression of cardiovascular disorders?

Cigarette smoking is common in societies worldwide and a growing body of evidence suggests that chronic cigarette smoking may affect the structure and function of cardiovascular system. The chronic exposure to high levels of nicotine, a major component of cigarette smoking, has been observed to play a pathogenic role in the induction and progression of cardiovascular disorders including cardiomyopathy and peripheral vascular disease. Nicotine alters the function of vascular endothelium, initiates the adhesion cascade and stimulates the vascular inflammatory events to induce atherosclerosis and hypertension. Moreover, nicotine has been noted to induce direct coronary spasm and ischemia, which develop coronary artery disease and myocardial infarction. In addition, nicotine stimulates the excessive release of impulses from sinoatrial node that may account for the induction of cardiac arrhythmia. The present review critically discussed the possible detrimental role of chronic nicotine exposure in cardiac and vascular endothelial dysfunction. Moreover, the signaling mechanisms involved in the pathogenesis of nicotine exposure-induced cardiovascular dysfunction have been discussed. In addition, the pharmacological interventions to ameliorate chronic nicotine exposure-induced cardiovascular abnormalities have been delineated.

Gene expression profiling of cultured cells from brainstem of newborn spontaneously hypertensive and Wistar Kyoto rats

The spontaneously hypertensive rat (SHR) is a good model to study several diseases such as the attention-deficit hyperactivity disorder, cardiopulmonary impairment, nephropathy, as well as hypertension, which is a multifactor disease that possibly involves alterations in gene expression in hypertensive relative to normotensive subjects. In this study, we used high-density oligoarrays to compare gene expression profiles in cultured neurons and glia from brainstem of newborn normotensive Wistar Kyoto (WKY) and SHR rats. We found 376 genes differentially expressed between SHR and WKY brainstem cells that preferentially map to 17 metabolic/signaling pathways. Some of the pathways and regulated genes identified herein are obviously related to cardiovascular regulation; in addition there are several genes differentially expressed in SHR not yet associated to hypertension, which may be attributed to other differences between SHR and WKY strains. This constitute a rich resource for the identification and characterization of novel genes associated to phenotypic differences observed in SHR relative to WKY, including hypertension. In conclusion, this study describes for the first time the gene profiling pattern of brainstem cells from SHR and WKY rats, which opens up new possibilities and strategies of investigation and possible therapeutics to hypertension, as well as for the understanding of the brain contribution to phenotypic differences between SHR and WKY rats.