Influenza A Virus Causes Histopathological Changes and Impairment in Functional Activity of Blood Vessels in Different Vascular Beds

New Directions in Infection-Associated Ischemic Stroke

The relationship between infections and stroke has not been fully characterized, probably delaying the development of specific treatments. This narrative review addresses mechanisms of stroke linked to infections, including hypercoagulability, endothelial dysfunction, vasculitis, and impaired thrombolysis. SARS-CoV-2, the virus that causes COVID-19, may promote the development of stroke, which may represent its most severe neurological complication. The development of specific therapies for infection-associated stroke remains a profound challenge. Perhaps the most important remaining issue is the distinction between infections that trigger a stroke versus infections that are truly incidental. This distinction likely requires the establishment of appropriate biomarkers, candidates of which are elevated levels of fibrin D-dimer and anticardiolipin/antiphospholipid antibodies. These candidate biomarkers might have potential use in identifying pathogenic infections preceding stroke, which is a precursor to establishing specific therapies for this syndrome.

Post-infection erectile dysfunction risk - comparing COVID-19 with other common acute viral infections: a large national claims database analysis

It is unknown if the risk of erectile dysfunction (ED) following Coronavirus-19 (COVID-19) infection is virus-specific. Our study assessed the risk of ED in COVID-19 patients as compared to patients with other common viral infections. The TriNetX COVID-19 Research Network was queried. We examined cohorts of men aged ≥18 years infected with: COVID-19, influenza, respiratory syncytial virus, enterovirus, acute viral hepatitis, mononucleosis, and herpes zoster. Men were included if they had at least one outpatient follow-up visit within 18 months and excluded if they had one of the other viruses of interest or a prior ED diagnosis or treatment, prostatectomy, pelvis radiation, or chronic hepatitis infection. Cohorts were propensity score matched and compared for differences in new ED diagnosis and/or prescription of phosphodiesterase-5 inhibitors (PDE5i). COVID-19 positive men were less likely to develop ED or have a PDE5i prescription than men with infected with herpes zoster [Relative Risk (RR): 0.37, 95% Confidence Interval (CI) 0.27-0.49] and more likely to develop ED or have a PDE5i prescription than men with no acute viral illness (RR: 1.33, 95% CI 1.25-1.42). In this national propensity-matched cohort study comparing post-infection ED risk and PDE5i prescriptions, we found that COVID-19 was no more likely to result in a diagnosis of ED or prescription of PDE5i when compared to all acute viral illnesses except herpes zoster, which was more likely to result in a diagnosis of ED or prescription of PDE5i when compared to COVID-19. These findings suggest an inflammatory etiology (perhaps due to cytokine release, endothelial dysfunction, or blunted hormone signaling) behind any acute infection can result in a heightened ED risk; however, further studies are required to investigate the connection between other viral infections and ED.

Influenza A(H1N1)pdm09 Virus Aggravates Pathology of Blood Vessels in Wistar Rats with Premorbid Acute Cardiomyopathy

Influenza virus can infect the vascular endothelium and cause endothelial dysfunction. Persons at higher risk for severe influenza are patients with acute and chronic cardiovascular disorders; however, the mechanism of influenza-induced cardiovascular system alteration remains not fully understood. The aim of the study was to assess the functional activity of mesenteric blood vessels of Wistar rats with premorbid acute cardiomyopathy infected with Influenza A(H1N1)pdm09 virus. For this, we determined (1) the vasomotor activity of mesenteric blood vessels of Wistar rats using wire myography, (2) the level of expression of three endothelial factors: endothelial nitric oxide synthase (eNOS), plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator (tPA) in the endothelium of mesenteric blood vessels using immunohistochemistry, and (3) the concentration of PAI-1 and tPA in the blood plasma using ELISA. Acute cardiomyopathy in animals was induced by doxorubicin (DOX) following infection with rat-adapted Influenza A(H1N1)pdm09 virus. The functional activity of mesenteric blood vessels was analyzed at 24 and 96 h post infection (hpi). Thus, the maximal response of mesenteric arteries to both vasoconstrictor and vasodilator at 24 and 96 hpi was significantly decreased compared with control. Expression of eNOS in the mesenteric vascular endothelium was modulated at 24 and 96 hpi. PAI-1 expression increased 3.47-fold at 96 hpi, while the concentration of PAI-1 in the blood plasma increased 6.43-fold at 24 hpi compared with control. The tPA concentration in plasma was also modulated at 24 hpi and 96 hpi. The obtained data indicate that influenza A(H1N1)pdm09 virus aggravates the course of premorbid acute cardiomyopathy in Wistar rats, causing pronounced dysregulation of endothelial factor expression and vasomotor activity impairment of mesenteric arteries.

Influenza A(H1N1)pdm09 Virus Alters Expression of Endothelial Factors in Pulmonary Vascular Endothelium in Rats

Influenza virus infection may cause endothelial activation and dysfunction. However, it is still not known to what extent the influenza virus can dysregulate the expression of various endothelial proteins. The aim of the study is to identify the level of expression of endothelial nitric oxide synthase (eNOS), plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator (tPA) in the pulmonary vascular endothelium, as well as the concentration of PAI-1 and tPA in the blood plasma in Wistar rats. Animals were intranasally infected with rat-adapted influenza A(H1N1)pdm09 virus. The expression of eNOS, PAI-1 and tPA in the pulmonary vascular endothelium was determined by immunohistochemistry; the concentration of PAI-1 and tPA was analyzed by ELISA at 24 and 96 h post infection (hpi). Thus, the expression of eNOS in the pulmonary vascular endothelium decreased by 1.9-fold at 24 hpi and increased by 2-fold at 96 hpi. The expression of PAI-1 in the pulmonary vascular endothelium increased by 5.23-fold and 6.54-fold at 24 and 96 hpi, respectively. The concentration of PAI-1 in the blood plasma of the rats decreased by 3.84-fold at 96 hpi, but not at 24 hpi. The expression of tPA in the pulmonary vascular endothelium was increased 2.2-fold at 96 hpi. The obtained data indicate the development of endothelial dysfunction that is characterized by the dysregulation of endothelial protein expression in non-lethal and clinically non-severe experimental influenza virus infection.