Blood Pressure, Proteases and Inhibitors

Blood pressure is controlled through a complex network of interacting peptide systems, principally involving the angiotensin, natriuretic peptide, endothelin and apelin families. The most complex and thoroughly investigated is the renin-angiotensin system (RAS) in which selective and potent inhibitors of the key biosynthetic proteolytic enzymes, renin and angiotensin-converting enzyme (ACE), have proved to be valuable drugs for the effective treatment of hypertension and heart failure, as well as other cardiovascular and renal disorders. Some of the other proteases in these pathways, e.g.neprilysin and ACE2, are also being explored as potential drug targets. © 2023 Elsevier Inc. All rights reserved.

The des-Arg9-bradykinin/B1R axis: Hepatic damage in COVID-19.

Patients infected by the SARS-CoV-2 virus are commonly diagnosed with threatening liver conditions associated with drug-induced therapies and systemic viral action. RNA-Seq data from cells in bronchoalveolar lavage fluid from COVID-19 patients have pointed out dysregulation of kallikrein-kinin and renin-angiotensin systems as a possible mechanism that triggers multi-organ damage away from the leading site of virus infection. Therefore, we measured the plasma concentration of biologically active peptides from the kallikrein-kinin system, bradykinin and des-Arg9-bradykinin, and liver expression of its proinflammatory axis, bradykinin 1 receptor (B1R). We measured the plasma concentration of bradykinin and des-Arg9-bradykinin of 20 virologically confirmed COVID-19 patients using a liquid chromatography-tandem mass spectrometry-based methodology. The expression of B1R was evaluated by immunohistochemistry from post-mortem liver specimens of 27 COVID-19 individuals. We found a significantly higher blood level of des-Arg9-bradykinin and a lower bradykinin concentration in patients with COVID-19 compared to a healthy, uninfected control group. We also observed increased B1R expression levels in hepatic tissues of patients with COVID-19 under all hepatic injuries analyzed (liver congestion, portal vein dilation, steatosis, and ischemic necrosis). Our data indicate that des-Arg9-bradykinin/B1R is associated with the acute hepatic dysfunction induced by the SARS-CoV-2 virus infection in the pathogenesis of COVID-19.

Angioedema induced by angiotensin-converting enzyme inhibitors: An analysis of hospitalizations during the covid-19 pandemic.

BACKGROUND: The pathogenesis of angioedema induced by angiotensin-converting enzyme inhibitors is based on the accumulation of bradykinin as a result of angiotensin-converting enzyme blockade. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to the angiotensin-converting enzyme 2 receptor, which may inhibit its production and thereby lead to an increase in bradykinin levels. Thus, SARS-CoV-2 infection may be a likely trigger for the development of angioedema. AIMS: This study aimed to analyze cases of hospitalizations of patients with angioedema associated with the use of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers during the coronavirus disease 2019 (COVID-19) pandemic. MATERIALS AND METHODS: This study retrospectively analyzed medical records of patients admitted to the Vitebsk Regional Clinical Hospital between May 2020 and December 2020 with isolated (without urticaria) angioedema while receiving angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. In all patients, smears from the naso and oropharynx for COVID-19 were analyzed by polymerase chain reaction. RESULT(S): Fifteen inpatients (9 men and 6 women) aged 44-72 years were admitted because of emergent events, of which 53.6% had isolated angioedema. In two cases, a concomitant diagnosis of mild COVID-19 infection was established with predominant symptoms of angioedema, including edema localized in the face, tongue, sublingual area, and soft palate. All patients had favorable disease outcomes. CONCLUSION(S): Patients with angiotensin-converting enzyme inhibitor-induced angioedema may require hospitalization to monitor upper respiratory tract patency. There were cases of a combination of angiotensin-converting enzyme inhibitor-induced angioedema and mild COVID-19. Issues requiring additional research include the effect of SARS- CoV-2 infection on the levels of bradykinin and its metabolites, the triggering role of COVID-19 in the development of angioedema in patients receiving angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, recommendations for the management of patients with angiotensin-converting enzyme inhibitor-induced angioedema, and a positive result for COVID-19.Copyright © 2020 Pharmarus Print Media All rights reserved.

COVID-19 disease and hereditary angioedema

Since December 2019, an outbreak of a novel coronavirus (SARS-CoV-2) infection causing COVID-19 disease has influenced the whole world. Angiotensin converting enzyme 2 (ACE2) receptors on type 2 pneumocytes in humans were determined as the entry for SARSCoV-2. Receptor binding and subsequently endocytosis of ACE2 diminish the cell membrane expression and also the function of ACE2. ACE2 is an enzyme involved in bradykinin metabolism. Lys-des-Arg9-BK occured with enzymatic cleaving of Lys-BK derived from low molecular weight kininogen is inactivated by ACE2 in tissues and it is a vasodilator agent having its own receptor named bradykinin B1. Non-metabolized Lys-des-Arg9-BK can be the reason for tissue vasodilation and increased vascular permeability in the patients with COVID-19. Increased bradykinin levels in patients with hereditary angioedema with C1-INH deficiency (C1-INH-HAE) do not cause increased SARS-CoV-2 infection or more severe disease. Although SARS-CoV-2 infection does not result in increased bradykinin levels, it can increase Lys-des-Arg9-BK levels.Copyright © 2020 Bilimsel Tip Yayinevi. All rights reserved.

Three-Day Icatibant on Top of Standard Care in Patients With Coronavirus Disease 2019 Pneumonia: A Randomized, Open-Label, Phase 2, Proof-of-Concept Trial.

BACKGROUND: We aimed to evaluate icatibant, a competitive antagonist of the bradykinin B2 receptors, for the treatment of inpatients with coronavirus disease 2019 (COVID-19) pneumonia admitted in the early hypoxemic stage. METHODS: The randomized, open-label clinical trial of icatibant for COVID-19 pneumonia (ICAT·COVID, registered as NCT04978051 at ClinicalTrials.gov) was conducted in Barcelona. Inpatients requiring supplemental but not high-flow oxygen or mechanical ventilation were allocated (1:1) to treatment with either three 30-mg icatibant doses/d for 3 consecutive days plus standard care or standard care alone, and followed for up to 28 days after initial discharge. The primary and key secondary outcomes were clinical response on study day 10/discharge and clinical efficacy at 28 days from initial discharge, respectively. RESULTS: Clinical response occurred in 27 of 37 patients (73.0%) in the icatibant group and 20 of 36 patients (55.6%) in the control group (rate difference, 17.42; 95% confidence interval [CI], -4.22 to 39.06; P = .115). Clinical efficacy ensued in 37 patients (100.0%) in the icatibant group and 30 patients (83.3%) in the control group (rate difference, 16.67; 95% CI, 4.49-28.84; P = .011). No patient died in the icatibant group, compared with 6 patients (16.7%) in the control group (P = .011). All patients but 1 had adverse events, which were evenly distributed between study arms. No patient withdrew because of adverse events. CONCLUSIONS: Adding icatibant to standard care was safe and improved both COVID-19 pneumonia and mortality in this proof-of-concept study. A larger, phase 3 trial is warranted to establish the clinical value of this treatment. CLINICAL TRIALS REGISTRATION: NCT04978051.

The impact of COVID-19 on people with bradykinin-mediated angioedema in the ITACA cohort

Background: The pandemic of Coronavirus disease 19 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV- 2), has become a global challenge in the last two years. SARS-CoV- 2 enters the cells of the infected subjects through angiotensin converting enzyme 2 (ACE-2), leading to its depletion on cell surface. ACE-2 activity is involved in the catabolism of des-Arg( 9)-bradykinin and increases the expression of angiotensin converting enzyme (ACE) in animal models. ACE in turn inactivates bradykinin. The infection has therefore the potential to cause a deregulation of the contact system and its pro-inflammatory activity, which could also contribute to the pathogenesis of COVID-19. Since bradykinin-mediated angioedema is generally thought to be the result of a poorly regulated contact system, it has been speculated that these patients are prone to severe SARS-CoV- 2 infection and that COVID-19 can in turn elicit angioedema attacks. We examined these hypotheses in a large group of bradykinin-mediated angioedema patients. Method(s): W e c onducted a m ulticenter r etrospective s tudy t argeting all the patients with hereditary angioedema (HAE) or acquired angioedema due to C1 inhibitor deficiency followed up by the centers of the Italian Network for Hereditary and Acquired Angioedema (ITACA). All accessible patients underwent a telephone interview between January 1st and March 31st 2021;we collected data about demographic and angioedema features, the occurrence of SARS-CoV- 2 positivity and COVID-19 outcomes from the beginning of the pandemic until March 31st 2021. A digital diary of attacks developed by ITACA helped us to collect attacks data. 15 centers participated in the survey. Result(s): 677 patients were included;52/677 reported SARS-CoV- 2 positivity (48 with hereditary and 4 with acquired C1 inhibitor deficiency). The incidence was 7.68% (confidence interval 5,79-9,95%), similar to the general population (6.04%). 4/52 patients (7.7%) reported severe COVID-19;the median disease duration was 15 days. One patient suffered a pulmonary thromboembolism;no deaths were reported. 27/52 patients (51,9%) had angioedema attacks during the infection, with a median of 1 attack per patient;severity of COVID-19 predicted more frequent and more severe angioedema attacks in a multivariate analysis (p < 0.001). Conclusion(s): COVID-19 does not seem more severe in bradykinin-mediated angioedema than in the general population. SARS-CoV- 2 infection can elicit angioedema attacks.

Systemic reaction triggered by SARS-COV- 2 infection in a patient with chronic autoimmune urticaria

Case report: Chronic urticaria is defined as the presence of urticaria for a period exceeding six weeks. Infections are known as possible triggers for urticaria manifestations, and, as such, SARS-CoV- 2 infection can be recognized as causative. An 8-year- old boy, with a previous history of idiopathic chronic urticaria, came to the Emergency Department for the appearance of generalized urticaria and lips angioedema associated with vomit and shortening of breath normal vital signs by age. Thus, due to the significant reaction, intravenous corticosteroids and antihistamines were promptly administered, with a rapid improvement of symptoms. Since the systemic reaction, the tryptase dosage was performed with the identification of an elevation at the time of the arrival and a complete normalization after the twelfth hour from the beginning of the reaction. Figure 1 shows the kinetic of the tryptase over time. SARS-CoV2 swab was performed before hospitalization and a positive test was identified. To investigate the etiopathogenesis of reaction, the patient was submitted to the extensive clinical, laboratory, and instrumental investigations that revealed only a positive in vitro basophil activation test (BAT) as evidence of functional serum histamine-releasing autoantibodies that are directed against IgE or high-affinity IgE receptors. The viral infection did not need any medication, and the urticaria was resolute in a couple of days. Daily treatment with oral antihistamines was then prescribed, and no further urticarious episodes occurred. A negative SARS-CoV- 2 swab was detected within 12 days of beginning symptoms. Approximately 40% of patients with idiopathic chronic urticaria have circulating antibodies versus IgE epitopes or the IgE receptor, but as it occurs in many autoimmune conditions, the presence of autoantibodies does not necessarily result in a disease phenotype. It is demonstrated that infections can elicit an autoimmune condition, and as our report shows, SARS-CoV2 could explain the reaction observed in our patient. The autoimmune precondition could have been the primer of the systemic reaction, pre-activating the mastocyte degranulation, as the tryptase elevation demonstrated. On the other hand, the SARS-CoV2 virus reducing the ACE2 expression, due to virus endocytosis, could create an imbalance in the RAS system, increasing the bradykinin levels. Bystander activation of pre-activated mastocytes caused by an inflammatory environment could explain the systemic reaction described above.

Subcutaneous administration of C1 inhibitor concentrate: Case report of a pediatric patient with hereditary angioedema

Case report Background: Hereditary angioedema (HAE) is a rare disease that usually manifests during childhood and is characterized by recurrent swelling episodes in various body tissues. Effective treatment options, including replacement therapy with C1 inhibitor (C1-INH) concentrate, are available for acute attacks and, for patients with high disease burden, for prophylaxis. More convenient than intravenous (IV) injections, and better suitable for patients with difficult venous access, is subcutaneous (SC) administration. However, treatment with SC prophylactic C1-INH is not yet approved in Europe for children < 12 years of age. Case Description: The boy presented to our clinic in 2014 at the age of 3, with a diagnosis of HAE due to C1-INH deficiency. During the last 3 months, he had been given IV C1-INH concentrate on-demand for HAE attacks. During the following year, the boy experienced monthly attacks at different body sites and had to be hospitalized several times for edema of the extremities and face, and abdominal colicky pain. At 5 to 6 years of age, attack frequency increased to once weekly and a first swelling of the trachea with dyspnea occurred. Over time, this led to repeated occurrence of panic attacks and psychological problems, which were exacerbated by social distancing during the coronavirus disease-19 pandemic. To mitigate disease burden, his therapy was switched to weekly prophylaxis with IV C1-INH, and the bradykinin receptor inhibitor icatibant was kept on hand as emergency medicine. Less than half a year later, attack frequency increased again and the regimen was changed to twice weekly. This led to drastic deterioration of venous access, so that a switch to SC prophylaxis became inevitable. The patient, now 10 years old, and his mother were trained in SC injection techniques and since June 2021, they administer twice weekly SC C1-INH (2000 International Units) at home, with no breakthrough attacks and significant improvement of quality of life. Conclusion(s): Because of high disease burden and impairment of quality of life due to high edema frequency, routine prophylaxis was chosen. In patients receiving frequent IV prophylaxis, occurrence of breakthrough attacks and deterioration of venous access warrants a switch to SC treatment. In the present case, this switch was unavoidable, although this treatment option is not approved for children. It allows the boy to self-administer his C1-INH and has improved his quality of life significantly.

COVID-related alteration in the balance between pro-and anti/inflammatory bioactive lipids and cytokines

COVID-19 caused by SARS-CoV-2 is an inflammatory condition involving mainly lungs, vascular endothelium, liver, heart, and brain with significant disturbances in the innate and adaptive immune responses. SARS-CoV-2 virus enters the cells by binding to ACE2 receptor that is present in many tissues. Despite the availability of effective vaccine(s) against SARS-CoV-2 and its variants current pandemic continues to cause significant morbidity and mortality The emergence of several mutant variants of SARS-CoV-2 is a major concern especially about the efficacy of current vaccines against these variants and other variants that are likely to emerge in the future. In this context, the observation that essential fatty acids (EFAs) such as linoleic acid (LA) and their metabolites can inactivate SARS-CoV-2, regulate inflammatory events and immune responses, and suppress inappropriate excess production of proinflammatory interleukin-6 (IL-6) and tumor necrosis factor-a (TNF-a), and bradykinin and thus, restore homeostasis is noteworthy. Of all the EFAs, LA and arachidonic acid (AA) are the most effective to inactivate SARS-CoV-2 and other similar viruses and prevent unwarranted inflammation, enhance wound healing by augmenting the production of anti-inflammatory bioactive lipids and cytokines. Since an imbalance between pro- and anti-inflammatory cytokine(s) and other molecules involved in inflammation and wound healing have a significant role in other serious diseases such as sepsis, ARDS (acute respiratory distress syndrome), ischemia-reperfusion injury and severe pneumonia(s), it remains to be seen whether administration of LA and AA and other fatty acids can prevent and suppress these life-threatening diseases in addition to COVID-19.

The therapeutic relevance of the Kallikrein-Kinin axis in SARS-cov-2-induced vascular pathology.

While coronavirus disease 2019 (COVID-19) begins as a respiratory infection, it progresses as a systemic disease involving multiorgan microthromboses that underly the pathology. SARS-CoV-2 enters host cells via attachment to the angiotensin-converting enzyme 2 (ACE2) receptor. ACE2 is widely expressed in a multitude of tissues, including the lung (alveolar cells), heart, intestine, kidney, testis, gallbladder, vasculature (endothelial cells), and immune cells. Interference in ACE2 signaling could drive the aforementioned systemic pathologies, such as endothelial dysfunction, microthromboses, and systemic inflammation, that are typically seen in patients with severe COVID-19. ACE2 is a component of the renin-angiotensin system (RAS) and is intimately associated with the plasma kallikrein-kinin system (KKS). As many papers are published on the role of ACE and ACE2 in COVID-19, we will review the role of bradykinin, and more broadly the KSS, in SARS-CoV-2-induced vascular dysfunction. Furthermore, we will discuss the possible therapeutic interventions that are approved and in development for the following targets: coagulation factor XII (FXII), tissue kallikrein (KLK1), plasma kallikrein (KLKB1), bradykinin (BK), plasminogen activator inhibitor (PAI-1), bradykinin B1 receptor (BKB1R), bradykinin B2 receptor (BKB2R), ACE, furin, and the NLRP3 inflammasome. Understanding these targets may prove of value in the treatment of COVID-19 as well as in other virus-induced coagulopathies in the future.

Complete, Rapid Resolution of Severe Bilateral Pneumonia and Acute Respiratory Distress Syndrome in a COVID-19 Patient: Role for a Unique Therapeutic Combination of Inhalations With Bromhexine, Higher Doses of Colchicine, and Hymecromone.

An otherwise healthy, 35-year-old man was hospitalized for the management of acute respiratory failure due to coronavirus disease 2019 (COVID-19)-related severe bilateral pneumonia and acute respiratory distress syndrome (ARDS). The patient therapeutic regimen included the widely accepted standard combination of oxygen, anticoagulation therapy; corticosteroids, non-steroidal anti-inflammatory drugs (NSAIDs), and antibiotics. A novel combination of colchicine, hymecromone, and bromhexine inhalations was added to the therapeutic regimen as part of our unique COVID-19 management institutional protocol. COVID-19-related severe bilateral pneumonia and acute respiratory distress syndrome (ARDS). The patient therapeutic regimen included the widely accepted standard combination of oxygen, anticoagulation therapy, corticosteroids, NSAIDs, and antibiotics. A novel combination of colchicine, hymecromone, and bromhexine inhalations was added to the therapeutic regimen as part of our unique COVID-19 management institutional protocol. Rapid clinical response on day 2, with a significant improvement of radiographic pulmonary changes on day 5, and improvement of laboratory results on days 5-7 were observed. The administration of inhalatory bromhexine in combination with high-dose colchicine and hymecromone was crucial for the positive outcome of the disease. This treatment regimen resulted in a four to five-fold decrease in the mortality of hospitalized patients.

Mass spectrometric study of variation in kinin peptide profiles in nasal fluids and plasma of adult healthy individuals.

BACKGROUND: The kallikrein-kinin system is assumed to have a multifunctional role in health and disease, but its in vivo role in humans currently remains unclear owing to the divergence of plasma kinin level data published ranging from the low picomolar to high nanomolar range, even in healthy volunteers. Moreover, existing data are often restricted on reporting levels of single kinins, thus neglecting the distinct effects of active kinins on bradykinin (BK) receptors considering diverse metabolic pathways. A well-characterized and comprehensively evaluated healthy cohort is imperative for a better understanding of the biological variability of kinin profiles to enable reliable differentiation concerning disease-specific kinin profiles. METHODS: To study biological levels and variability of kinin profiles comprehensively, 28 healthy adult volunteers were enrolled. Nasal lavage fluid and plasma were sampled in customized protease inhibitor prespiked tubes using standardized protocols, proven to limit inter-day and interindividual variability significantly. Nine kinins were quantitatively assessed using validated LC-MS/MS platforms: kallidin (KD), Hyp4-KD, KD1-9, BK, Hyp3-BK, BK1-8, BK1-7, BK1-5, and BK2-9. Kinin concentrations in nasal epithelial lining fluid were estimated by correlation using urea. RESULTS: Circulating plasma kinin levels were confirmed in the very low picomolar range with levels below 4.2 pM for BK and even lower levels for the other kinins. Endogenous kinin levels in nasal epithelial lining fluids were substantially higher, including median levels of 80.0 pM for KD and 139.1 pM for BK. Hydroxylated BK levels were higher than mean BK concentrations (Hyp3-BK/BK = 1.6), but hydroxylated KD levels were substantially lower than KD (Hyp4-KD/KD = 0.37). No gender-specific differences on endogenous kinin levels were found. CONCLUSIONS: This well-characterized healthy cohort enables investigation of the potential of kinins as biomarkers and would provide a valid control group to study alterations of kinin profiles in diseases, such as angioedema, sepsis, stroke, Alzheimer's disease, and COVID-19.

Molecular Bases of Serotonin Reuptake Inhibitor Antidepressant-Attributed Effects in COVID-19: A New Insight on the Role of Bradykinins.

Widely available effective drugs to treat coronavirus disease-2019 (COVID-19) are still limited. Various studies suggested the potential contribution of selective serotonin-reuptake inhibitor (SSRI) antidepressants to alleviate the clinical course of COVID-19. Initially, SSRI antidepressant-attributed anti-COVID-19 activity was attributed to their direct agonistic or indirect serotonin-mediated stimulation of sigma-1 receptors (Sig1-R). Thereafter, attention was drawn to the property of SSRI antidepressants to decrease ceramide production, as functional inhibitors of acid sphingomyelinase. Ceramides are cell membrane waxy lipids formed by sphingosine and a fatty acid, playing a major role in receptor signaling and infection. In COVID-19 patients, ceramide production is increased due to acid sphingomyelinase activation. Here, we aimed to review the relationships between bradykinins and the proposed pathways supporting SSRI antidepressant-attributed effectiveness in COVID-19. In COVID-19 patients, bradykinin receptor-B1 stimulation is enhanced following the downregulation of angiotensin-converting enzyme-2, which is responsible for the inactivation of des-Arg9-bradykinin, a bradykinin metabolite, contrasting with the decrease in bradykinin receptor-B2 (BDKRB2) stimulation, which results from the inhibition of cathepsin L, a kininogenase involved in bradykinin production and present at the infection site. Sig1-R stimulation modulates the inflammatory response by regulating cytokine production and counterbalances COVID-19-attributed BDKRB2 inhibition by potentiating its effects on the cytosolic calcium concentration. Moreover, the beneficial effects obtained with acid sphingomyelinase inhibition are parallel to those expected with BDKRB2 stimulation in COVID-19. Altogether, these findings suggest that one ultimate pathway of SSRI antidepressant-attributed anti-COVID-19 activity is the potentiation of BDKRB2 effects shown to be inhibited in COVID-19. In conclusion, SSRI antidepressants are able to interact positively with the pathophysiological mechanisms involved in COVID-19. However, their exact benefits in preventing morbidities or improving the outcome in COVID-19 patients remain unknown.

SARS COV-2 AS A RISK FOR ANGIOEDEMA

CASE: This is a 41-year-old man who was admitted to the medical floor with mild COVID-19 symptoms without hypoxia. He had End Stage Renal Disease (ESRD) on Hemodialysis (HD), failed renal transplant, Hypertension and Schizophrenia. Patient had no relevant family history. Medications included Aspirin, Atorvastatin, Nifedipine, Benztropine, and Haloperidol. Patient had allergy to shellfish products. He tested positive a week prior to admission with mild cough no fever or hypoxia. As symptoms worsened, he presented to emergency department and was admitted because of his immunocompromised status. The night of admission, he developed wheezing and stridor, swelling of face and lips, and altered mental status. It was difficult to pass endotracheal tube due to swollen airways. Vital signs were stable except for a low oxygen saturation. Physical examination significant for stridor and swelling of the face and lips. Laboratory values were not significant. We reviewed and none of them was newly started or associated with risks of angioedema. He had no history of previous similar episodes. Patient was given anti-histamines and steroids with slight improvement. Flexible laryngoscopy was performed showing swollen epiglottis and aryepiglottic folds. He ended up getting a tracheostomy as he was regarded as a high risk to be liberated from intubation. IMPACT/DISCUSSION: Few other cases of COVID-associated angioedema have been reported in the literature, majority of the cases explained were in African American patients. The features of angioedema reported like the traditional angioedema, swelling of the face, lips and airways. This angioedema developed within 7 days of detection of COVID-19 in our case and >10 days in the previously reported cases. Angioedema develops due to increased levels of Bradykinin (BK) and its metabolites due to increased expression or decreased degradation. Angiotensin Converting Enzyme (ACE) with other enzymes prevent angioedema by degradation of BK and its metabolites . African Americans, have genetic susceptibility which leads to lower levels of other enzymes involved in the Bradykinin metabolism, thus ACE blockade put them at a higher risk of angioedema. The association of COVID-19 with ACE2 and its subsequent disruption of ACE activity is thought to be the reason behind the development of angioedema. Most of the published articles are either observational or sporadic case reports. More thorough study might help identify further mechanisms and if there is a direct true causal relationship between COVID-19 infection and angioedema or if it is the result of a “second hit,” as it was called by authors of another case that involved a Caucasian male with hypertension who has been using Lisinopril for years with no previously reported complaint. CONCLUSION: SARS CoV-2 should be suspected as cause for angioedema. Further studies needed to establish modalities for diagnosis, management and prevention in high-risk patients.

A comprehensive review on current understanding of bradykinin in COVID-19 and inflammatory diseases.

Bradykinin, a member of the kallikrein-kinin system (KKS), is a potent, short-lived vasoactive peptide that acts as a vasodilator and an inflammatory mediator in a number of signaling mechanisms. Bradykinin induced signaling is mediated through kinin B1 (BDKRB1) and B2 (BDKRB2) transmembrane receptors coupled with different subunits of G proteins (Gαi/Gα0, Gαq and Gß1γ2). The bradykinin-mediated signaling mechanism activates excessive pro-inflammatory cytokines, including IL-6, IL-1ß, IL-8 and IL-2. Upregulation of these cytokines has implications in a wide range of clinical conditions such as inflammation leading to fibrosis, cardiovascular diseases, and most recently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In SARS-CoV-2 infection, bradykinin is found to be at raised levels and is reported to trigger a diverse array of symptoms. All of this brings bradykinin to the core point as a molecule of immense therapeutic value. Our understanding of its involvement in various pathways has expanded with time. Therefore, there is a need to look at the overall picture that emerges from the developments made by deciphering the bradykinin mediated signaling mechanisms involved in the pathological conditions. It will help devise strategies for developing better treatment modalities in the implicated diseases. This review summarizes the current state of knowledge on bradykinin mediated signaling in the diverse conditions described above, with a marked emphasis on the therapeutic potential of targeting the bradykinin receptor.

Impaired Kallikrein-Kinin System in COVID-19 Patients' Severity.

COVID-19 has emerged as a devastating disease in the last 2 years. Many authors appointed to the importance of kallikrein-kinin system (KKS) in COVID-19 pathophysiology as it is involved in inflammation, vascular homeostasis, and coagulation. We aim to study the bradykinin cascade and its involvement in severity of patients with COVID-19. This is an observational cohort study involving 63 consecutive patients with severe COVID-19 pneumonia and 27 healthy subjects as control group. Clinical laboratory findings and plasma protein concentration of KKS peptides [bradykinin (BK), BK1-8], KKS proteins [high-molecular weight kininogen (HK)], and KKS enzymes [carboxypeptidase N subunit 1 (CPN1), kallikrein B1 (KLKB1), angiotensin converting enzyme 2 (ACE2), and C1 esterase inhibitor (C1INH)] were analyzed. We detected dysregulated KKS in patients with COVID-19, characterized by an accumulation of BK1-8 in combination with decreased levels of BK. Accumulated BK1-8 was related to severity of patients with COVID-19. A multivariate logistic regression model retained BK1-8, BK, and D-dimer as independent predictor factors to intensive care unit (ICU) admission. A Youden's optimal cutoff value of -0.352 was found for the multivariate model score with an accuracy of 92.9%. Multivariate model score-high group presented an odds ratio for ICU admission of 260.0. BK1-8 was related to inflammation, coagulation, and lymphopenia. Our data suggest that BK1-8/BK plasma concentration in combination with D-dimer levels might be retained as independent predictors for ICU admission in patients with COVID-19. Moreover, we reported KKS dysregulation in patients with COVID-19, which was related to disease severity by means of inflammation, hypercoagulation, and lymphopenia.

A Rare Cause of Angioedema - A Novel Case Report

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is well described as an etiology to severe acute respiratory distress syndrome (ARDS). However, rare immunologic and allergic manifestations may also occur from this infection. We report a novel case of angioedema occurring in the setting of COVID-19 infection in a fully vaccinated patient. Case Report: A 61-yearold COVID-19 vaccinated female with hypertension presented to the emergency department with tongue and lip swelling, odynophagia, dysphonia, and difficulty breathing. She denied personal or family history of allergies, anaphylaxis, or angioedema. Her home medications included Aspirin, methadone, Seroquel, and Klonopin, with no recent changes reported. Physical exam was notable for significant lip and tongue edema, audible dysphonia, and bilateral end-inspiratory wheezing. She was hypoxemic and placed on nasal cannula. Laboratory findings revealed lymphopenia, elevated inflammatory proteins, including C-reactive protein (57), Lactate dehydrogenase (LDH) (238), and D-dimer (11.52). Functional C1 esterase inhibitor levels (>91) were normal. Nasal PCR swab returned positive for SARS-CoV-2. Ear, nose, and throat specialist was consulted given concern for angioedema, and flexible nasolaryngoscopy was performed revealing uvular, epiglottic, and bilateral arytenoid edema concerning for impending airway compromise. The patient was initiated on intravenous methylprednisolone, epinephrine, antihistamines, tranexamic acid and admitted to the medical intensive care unit (ICU). She was monitored closely in the ICU with subsequent improvement of the angioedema and resolution of the hypoxemia. She was discharged with an oral steroid regimen and scheduled for a follow-up appointment with an allergist. Discussion: There exists only a handful of case reports describing angioedema in patients with COVID-19 infection. In those reports, patients also had normal C1 esterase inhibitor levels and no personal or family history of inherited angioedema. Interestingly, our patient was vaccinated six months prior to her presentation. The association between SARS-CoV-2 and angiotensinconverting enzyme 2 (ACE-2), the primary receptor for viral entry into the epithelial cells of the lungs, could be a potential explanation for the occurrence of angioedema. ACE-2 plays a pivotal role in inhibiting a potent ligand of bradykinin receptor 1, Arginine bradykinin. It has been postulated that SARS-CoV-2 downregulation of ACE-2 leads to elevated angiotensin II levels and subsequent activation of the bradykinin pathway. Excessive bradykinin production generates high levels of nitric oxide and prostaglandins, resulting in vasodilation, increased vascular permeability, and angioedema. This case highlights the importance of recognizing atypical and rare presentations of COVID-19 infection, especially angioedema, given its sudden onset and life-threatening complications.

SARS-CoV-2 SPIKE PROTEIN DESTABILIZES MICROVASCULAR HOMEOSTASIS

Background: SARS-CoV-2 infection can compromise respiratory function and cause thrombotic events. SARS-CoV-2 binds to and mediates downregulation of angiotensin converting enzyme 2 (ACE2) on infected cells. Diminished enzymatic activity of ACE2 could result in increased concentrations of the pro-inflammatory molecules angiotensin II and bradykinin, contributing to SARS-CoV-2 pathology. Methods: Immunofluorescence microscopy and digital image data quantification, Computer assisted molecular docking analyses, Western blot. Results: Using immunofluorescence microscopy of lung tissues from uninfected and SARS-CoV-2 infected individuals, we find evidence that ACE2 is highly expressed in the pulmonary alveolar epithelium and is significantly reduced along the alveolar lining of SARS-CoV-2 infected lungs. Ex vivo analyses indicate that ACE2 is readily detected on primary human pulmonary alveolar epithelial and primary human aortic endothelial cells (HAoECs). Exposure of these cells to recombinant SARS-CoV-2 spike protein was sufficient to reduce surface ACE2 expression. Moreover, exposure of HAoECs to spike protein induced endothelial dysfunction (increased expression of von Willebrand Factor and decreased expression of Krüppel-like Factor 2), caspase activation, and apoptosis. Exposure of HAoECs to bradykinin (BK, 10μ M) induced calcium signaling and endothelial dysfunction but did not adversely affect viability. Computer assisted analyses of molecules with potential to bind bradykinin receptor B2 (BKRB2) suggested a potential role for aspirin as a bradykinin antagonist. When tested in our in vitro model, we found that aspirin (1μM) could significantly blunt cell signaling, and endothelial dysfunction caused by bradykinin in these cells. Conclusion: SARS-CoV-2 causes complex effects on microvascular homeostasis that potentially contribute to organ dysfunction and coagulopathies. Reduced ACE2 enzymatic activity could contribute to inflammation and pathology in the lung. Our studies add to this understanding by providing evidence that spike protein alone can mediate adverse effects on vascular cells. Understanding these mechanisms of pathogenesis may provide rationale for interventions, such as interference with the interactions of spike protein or bradykinin with endothelial cells, that could limit microvascular events associated with SARS-CoV-2 infection and stabilize microvascular homeostasis in COVID-19 disease.

Management of Patients with Hereditary Angioedema During the COVID-19 Pandemic

Objective: The aim of this study was to determine the clinical course and treatment outcomes of patients with hereditary angioedema (HAE) after infection with coronavirus disease 2019 (COVID-19). Materials and Methods: Thirty-nine patients with HAE were included in this study. These patients were regularly followed up over phone calls since the first COVID-19 case was seen in our country. Patients were asked to visit the hospital if there was a history of contact with a confirmed COVID-19 patient or if the patient developed clinical symptoms of COVID-19. Results: There were 21 (54%) patients with type I HAE, and 18 (46%) with type II HAE. All patients received treatment for angioedema attacks (C1-inhibitor [C1-INH], icatibant), and seven (20%) received long-term prophylaxis (danazol). Treatment for attacks was continued for all patients during the pandemic. Patients taking danazol were switched to long-term prophylaxis using the C1-INH concentrate. Eleven (28%) patients with HAE developed COVID-19 during this study. Only one patient had severe COVID-19. Six patients (54.5%) were diagnosed with type II HAE, and five (45.5%) were diagnosed with type I HAE. The most common COVID-19 symptoms were fever (7/11;64%) and myalgia (6/11;55%). Mild angioedema attacks were experienced by 36% (4/11) of the HAE patients diagnosed with COVID-19. Icatibant was used in all patients. Conclusion: Agents used for HAE block the kallikrein-kinin system and may be useful in the treatment of COVID-19. Considering their beneficial effects on COVID-19, it is recommended that HAE patients should continue the use of agents blocking the kallikrein-kinin system.

The Dysregulation of the Renin-Angiotensin System in COVID-19 Studied by Serum Proteomics: Angiotensinogen Increases with Disease Severity.

(1) Background: ACE and CPN serum activity correlated with disease severity in an earlier study of 45 hospitalized COVID-19 patients. The serum protein profile was investigated in the same cohort here to shed more light on the involvement of the renin-angiotensin system (RAS). (2) Methods: High-definition mass spectrometry-based protein expression analysis was performed, followed by multivariate statistical and network analyses. (3) Results: The protein profiles of hospitalized patients (HoP) differed significantly from those of convalescent and healthy probands. Surprisingly, HoP samples separated into six groups according to their protein profiles: group (G) 1 represented the youngest and the least afflicted patients, and G6 the oldest and critically ill patients. At least two major pathophysiological schemes were indicated based on differing involvement of the kallikrein-kinin system (KKS), the RAS and complement activation. The serum angiotensinogen concentration increased with disease severity. (4) Conclusions: The important role of the RAS in the response to COVID-19 infection was substantiated, but other pathways such as the KKS, plasminogen activation and complement activation influence the systemic response to the infection.