COVID-19 pathology is mainly associated to a pulmonary disease which sometimes might result in an uncontrollable storm related to inflammatory diseases which could be fatal. It is well known that phosphodiesterase enzyme type 5 inhibitors (PDE5Is), such as sildenafil, have been successfully developed for the treatment of pulmonary arterial hypertension; interestingly, more recently, it was shown that PDE5Is might be also anti-inflammatory. Therefore, it would be of interest to question about the use of PDE5Is to overcome the COVID-19 storm, as much as PDE5 is mainly present in the lung tissues and vessels.
SARS-CoV-2 by the direct cytopathic effect or indirectly through the propagation of pro-inflammatory cytokines could cause endothelial dysfunction (ED) and oxidative stress (OS). It has been reported that OS is triggered by various types of viral infections, including SARS-CoV-2. Into the bargain, allopurinol is regarded as a potent antioxidant that acts through inhibition of xanthine oxidase (XO), which is an essential enzyme of purine metabolism. Herein, the present study aimed to find the potential protective effects of allopurinol on the biomarkers of OS and ED in patients with severe Covid-19. This single-center cohort study recruited 39 patients with mild-moderate Covid-19 compared with 41 patients with severe Covid-19. Nineteen patients with severe Covid-19 were on the allopurinol treatment because of underlying chronic gout 3 years ago compared with 22 Covid-19 patients not on this treatment. The recruited patients were allocated into three groups: group I, mild-moderate Covid-19 on the standard therapy ( n = 39); group II, severe Covid-19 patients on the standard therapy only ( n = 22); and group III, severe Covid-19 patients on the standard therapy plus allopurinol ( n = 19). The duration of the study was 3 weeks from the time of hospitalization till the time of recovery. In addition, inflammatory biomarkers (D-dimer, LDH, ferritin, CRP, procalcitonin), neutrophil–lymphocyte ratio (NLR), endothelin-1 (ET-1), uric acid and oxidative stress index (OSI), CT scan score, and clinical score were evaluated at the time of admission and discharge regarding the effect of allopurinol treatment adds to the standard treatment of Covid-19. Allopurinol plus standard treatment reduced LDH, ferritin, CRP, procalcitonin, and ET-1 serum level significantly ( P < 0.05) compared with Covid-19 patients on standard treatment. Besides, neutrophil (%), lymphocyte (%), and neutrophil–lymphocyte ratio (NLR) were reduced in patients with severe Covid-19 on standard treatment plus allopurinol compared with Covid-19 patients on standard treatment alone ( P < 0.01). OSI was higher in patients with severe Covid-19 than mild-moderate Covid-19 patients ( P = 0.00001) at admission. At the time of discharge, the oxidative status of Covid-19 patients was significantly improved compared with that at admission ( P = 0.01). In conclusion, Covid-19 severity is linked with high OS and inflammatory reaction with ED development. High uric acid in patients with severe Covid-19 is correlated with high OS and inflammatory biomarkers. Allopurinol with standard treatment in patients with severe Covid-19 reduced oxidative and inflammatory disorders with significant amelioration of ED and clinical outcomes.
Novel coronavirus (COVID-19) led to infected pneumonia and acute respiratory distress syndrome (ARDS) and acute kidney injury (AKI). The entry-point receptor for COVID-19 is angiotensin-converting enzyme 2 (ACE2) at lung, and dipeptidyl peptidase-4 (DPP-4) is a receptor for Middle East respiratory syndrome coronavirus (MERS-CoV). There is 80% similarity between MERS-CoV and COVID-19. This study was planned to review the potential link between the incidence and severity of COVID-19 regarding the modulation of DPP-4 and ACE2 by DPP-4 and renin angiotensin system (RAS). In COVID-19, SARS-CoV2 binds ACE2 which is highly expressed by the epithelial cells of the blood vessel, intestine, and lung. However, pulmonary ACE2 seems to be a protective defense pathway during ARDS. DPP-4 is not concerned with the entry of COVID-19 but mediates the inflammatory reactions and cytokine storm that induced ARDS and AKI by COVID-19. The interaction between DPP4i and RAS inhibitors seem to augment the expression of AT2 receptor and ACE2 which are under extensive researches to find the pathophysiological pathway of COVID-19 infection. This beneficial interaction between DPP4i and RAS shed light for possible attenuation of COVID-19-induced ARDS and AKI mainly in critically ill patients with systemic hypertension.
Orexin is a neuropeptide secreted from lateral hypothalamus and pre-frontal cortex concerned in the wakefulness and excitement. This study aimed to review the possible neurobiological effect of orexin. A diversity of search strategies was adopted and assumed which included electronic database searches of Medline and PubMed using MeSH terms, keywords, and title words during the search. Orexin plays a vital role in activation of learning, memory acquisition, and consolidation through activation of monoaminergic system, which affect cognitive flexibility and cognitive function. Orexin stimulates adrenocorticotropin and corticosteroid secretions via activation of central corticotropin-releasing hormone. Cerebrospinal fluid (CSF) and serum orexin serum levels are reduced in depression, schizophrenia, and narcolepsy. However, high orexin serum levels are revealed in drug addictions. Regarding neurodegenerative brain diseases, CSF and serum orexin serum levels are reduced Parkinson disease, Alzheimer dementia, Huntington's disease, amyotrphic lateral sclerosis, and multiple sclerosis. Orexin antagonist leads to significant reduction of sympathetic over-activity during withdrawal syndrome. As well, orexin antagonist improves sleep pattern. Orexinergic system is involved in the different psychiatric and neurological disorders; therefore, targeting of this system could be possible novel pathway in the management of these disorders. In addition, measurement of CSF and serum orexin levels might predict the relapse and withdrawal of addict patients.
The pathogenesis of SARS-CoV-2 infection is related to the direct cytopathic effect and associated hyper-inflammatory due to exaggerated immune response. Different experimental and clinical studies revealed that other biomarkers could be used to determine the Covid-19 severity, such as D-dimer, procalcitonin, C-reaction protein (CRP), IL-6, and ferritin. Calprotectin (CP) is associated with intestinal inflammation, intestinal injury, and different respiratory diseases such as cystic fibrosis. Thus, CP might be a possible biomarker linking intestinal injury and acute lung injury (ALI) in Covid-19. Therefore, this study aimed to find a potential role of CP regarding GITI and ALI in Covid-19. CP is a complex protein consisting of S100A8 and S100A9, belongs to the Ca+2-binding proteins S100 family abundant in the cytosol of neutrophils and expressed on the monocyte membranes, macrophages, and intestinal epithelial cells. CP is a proinflammatory protein that acts through activation of the receptor for the advanced glycation end product (RAGE) and toll-like receptor 4 (TLR4). CP is a biomarker of neutrophil activation and is released following the turnover of neutrophils. CP could be controversial; it increases airway inflammation or protects lung and airway epithelium from an exaggerated immune response. Therefore, a high level of CP in different respiratory disorders might be protective and compensate against abnormal immune responses. CP level is high in Covid-19 and correlated with Covid-19 severity and oxygen demand due to activation release of proinflammatory cytokines and inflammatory signaling pathways. Therefore, CP level is elevated in both ALI and intestinal inflammation so that it could be a potential biomarker link the respiratory and intestinal injury in Covid-19.
The novel coronavirus which is also called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is responsible for COVID-19 (coronavirus disease 2019). SARS-CoV-2 is known to cause substantial pulmonary disease, including pneumonia and acute respiratory distress syndrome (ARDS), clinicians have observed many extra-pulmonary manifestations of COVID-19. SARS-CoV-2 infection is associated with a variety of pro-inflammatory mediators that may play important roles in the pathophysiology of cardiac and arrhythmic complications. Systemic inflammatory response syndrome (cytokine storm) is another putative mechanism of myocardial injury. In addition to lung damage, there may be significant cardiac involvement in patients with COVID-19, which is responsible for worsening the clinical condition of the host. The main cardiac manifestations can be oedema, pericarditis, cardiac fibrosis, myocarditis, impairment of contractile function and cardiac electrophysiology. The cardiac status of patients with ongoing SARS-CoV-2 infection of surviving patients in convalescence period should be carefully monitored.
Primary infection of SARS-CoV-2 (novel coronavirus or 2019-nCoV), which leads to Covid-19, targets specific cells, such as nasal, bronchial epithelial and pneumocytes, through the viral structural spike (S) protein that binds to the angiotensin-converting enzyme 2 (ACE2) receptor. Also, type 2 transmembrane serine protease (TMPRSS2) present in the host cell promotes viral uptake by cleaving ACE2 and triggering the SARS-CoV-2 S protein, which facilitates SARS-CoV-2 entry into host cells. One of the TMPRSS2 inhibitors with a greater distribution capacity into the lung tissue is bromhexine hydrochloride which attenuates the entry and proliferation of SARS-CoV-2. Bromhexine is an effective drug in the management and treatment of Covid-19 pneumonia via targeting ACE2/ TMPRSS2 pathway. However, prospective and controlled clinical trials are recommended to confirm this observation.
Introduction: Covid-19 is linked with the development of cardio-metabolic disorders, including dyslipidemia, dysregulation of high-density lipoprotein (HDL), and low-density lipoprotein (LDL). Furthermore, SARS-Co-2 infection is associated with noteworthy changes in lipid profile, which is suggested as a possible biomarker to support the diagnosis and management of Covid-19.Methods: This paper adopts the literature review method to obtain information about how Covid-19 affects high-risk group patients and may cause severe and critical effects due to the development of acute lung injury and acute respiratory distress syndrome. A narrative and comprehensive review is presented. Results: Reducing HDL in Covid-19 is connected to the disease severity and poor clinical outcomes, suggesting that high HDL serum levels could benefit Covid-19. SARS-CoV-2 binds HDL, and this complex is attached to the co-localized receptors, facilitating viral entry. Therefore, SARS-CoV-2 infection may induce the development of dysfunctional HDL through different
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