Severe COVID-19: A multifaceted viral vasculopathy syndrome

Alveolar Macrophages in Viral Respiratory Infections: Sentinels and Saboteurs of Lung Defense

Respiratory viral infections continue to cause pandemic and epidemic outbreaks in humans and animals. Under steady-state conditions, alveolar macrophages (AlvMϕ) fulfill a multitude of tasks in order to maintain tissue homeostasis. Due to their anatomic localization within the deep lung, AlvMϕ are prone to detect and react to inhaled viruses and thus play a role in the early pathogenesis of several respiratory viral infections. Here, detection of viral pathogens causes diverse antiviral and proinflammatory reactions. This fact not only makes them promising research targets, but also suggests them as potential targets for therapeutic and prophylactic approaches. This review aims to give a comprehensive overview of the current knowledge about the role of AlvMϕ in respiratory viral infections of humans and animals.

The utility of the normal thin section skin biopsy in the assessment of systemic/extracutaneous disease and small fiber neuropathy

Diseases reflective of multiorgan vascular injury of diverse etiology, peripheral nerve disease, dysautonomia syndromes, and intravascular lymphoma may exhibit abnormalities on a normal skin biopsy that may be instrumental in establishing a diagnosis. A retrospective review of our database was conducted to uncover cases where a normal skin biopsy was performed to rule in or out such systemic diseases as complement-driven thrombotic microvascular disease (including atypical hemolytic uremic syndrome, posttransplant thrombotic microangiopathy, and severe or critical COVID-19), systemic capillary leak syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) intravascular B cell lymphoma, small fiber neuropathy, dysautonomia syndromes, and mast cell activation syndrome. Among the special studies were immunohistochemical staining to detect C5b-9, CD56, and myxovirus resistance protein A, as well as mast cell, B and T cell markers. Characteristic patterns were critical in establishing diagnoses such as : increased C5b-9 microvascular deposition in the deltoid area (atypical hemolytic uremic syndrome, posttransplant thrombotic microangiopathy, catastrophic antiphospholipid antibody syndrome, and severe or critical COVID-19); enhanced type I interferon signaling (systemic capillary leak syndrome); ultrastructural arteriopathic changes (CADASIL); reduced cutaneous autonomic innervation in the lower extremities (small fiber neuropathy and postural orthostatic tachycardia syndrome); presence of intravascular lymphocytes on biopsy of abdominal, thigh, and buttock skin (intravascular B cell lymphoma); and a higher than normal density of mast cells in the absence of other inflammatory cell types (mast cell activation syndrome). The skin is clearly a critical window for understanding extracutaneous disease, a concept well exemplified by the myriad of diseases suggested by the microscopic and/or ultrastructural examination of clinically normal skin and therefore establishing the normal skin biopsy as an important tool for understanding certain extracutaneous reactive, neoplastic and paraneoplastic syndromes as well as small fiber neuropathy.

TLR2/NF-κB signaling in macrophage/microglia mediated COVID-pain induced by SARS-CoV-2 envelope protein

Pain has become a major symptom of long COVID-19 without effective therapy. Apart from viral infection pathological process, SARS-CoV-2 membranal proteins (envelope [S2E], spike [S2S] and membrane [S2M]) also present pro-inflammatory feature independently. Here, we aim to uncover the neuroinflammatory mechanism of COVID-pain induced by SARS-CoV-2 membranal proteins. We detected the three proteins in both peripheral sensory ganglions and spinal dorsal horn of COVID-19 donors. After intradermal and intrathecal injection, only S2E triggered pain behaviors, accompanied with upregulated-phosphorylation nuclear factor kappa B (NF-κB), which was significantly attenuated by minocycline in mice. We further identified Toll-like receptor 2 (TLR2) among TLRs as the target of S2E to evoke inflammatory responses leading to COVID-pain. This study identified the nociceptive effect of S2E through directly interacting with macrophage/microglia TLR2 and inducing the following NF-κB inflammatory storm. Clearing away S2E and inhibiting macrophage/microglia TLR2 served as perspective therapeutic strategies for COVID-19 pain.

The effect of long-term COVID-19 infection on maternal and fetal complications: a retrospective cohort study conducted at a single center in China

Investigate the effect of long-term COVID-19 on maternal and fetal complications. A retrospective cohort study was conducted. A total of 623 pregnant women who delivered in Kunming First People's Hospital from November 1, 2022 to July 31, 2023 were selected. By employing statistical methods, we compared the associations between maternal and fetal complications in pregnant women with acute COVID-19 during pregnancy, long-term COVID-19, and non-COVID-19 pregnant women. In the final 623 samples, there were 209 pregnant women with acute COVID-19, 72 pregnant women with long-term COVID-19, and 342 pregnant women without COVID-19. The epidemiological and clinical characteristics of all subjects were similar. Pregnant individuals who developed long-term COVID-19 during their pregnancy had an increased risk of experiencing gestational hypertension (OR 3.344, 95% CI 1.544-7.243), gestational diabetes mellitus (OR 2.301, 95% CI 1.290-4.102), and fetal intrauterine growth restriction (OR 2.817, 95% CI 1.385-5.952). Multivariate binary logistic regression analysis showed that this association remained consistent even after adjusting for confounders and performing subgroup analyses. Other maternal and fetal complications, such as premature rupture of membranes, preterm delivery, neonatal asphyxia, and transfer of neonates to NICU, did not exhibit statistically significant associations. After linear regression analysis, the platelet count (β: - 0.127, 95% CI - 0.001-0.000) of pregnant women with long-term COVID-19 was slightly lower than that of non-COVID-19 pregnant women, and the other coagulation parameters were not statistically significant. The incidence of gestational hypertension, gestational diabetes mellitus and fetal intrauterine growth restriction in pregnant women with long-term COVID-19 is significantly increased, but it does not further increase the coagulation status.

Acute neutrophilic vasculitis (leukocytoclasia) in 36 COVID-19 autopsy brains

BACKGROUND

Hypercytokinemia, the renin-angiotensin system, hypoxia, immune dysregulation, and vasculopathy with evidence of immune-related damage are implicated in brain morbidity in COVID-19 along with a wide variety of genomic and environmental influences. There is relatively little evidence of direct SARS-CoV-2 brain infection in COVID-19 patients.

METHODS

Brain histopathology of 36 consecutive autopsies of patients who were RT-PCR positive for SARS-CoV-2 was studied along with findings from contemporary and pre-pandemic historical control groups. Immunostaining for serum and blood cell proteins and for complement components was employed. Microcirculatory wall complement deposition in the COVID-19 cohort was compared to historical control cases. Comparisons also included other relevant clinicopathological and microcirculatory findings in the COVID-19 cohort and control groups.

RESULTS

The COVID-19 cohort and both the contemporary and historical control groups had the same rate of hypertension, diabetes mellitus, and obesity. The COVID-19 cohort had varying amounts of acute neutrophilic vasculitis with leukocytoclasia in the microcirculation of the brain in all cases. Prominent vascular neutrophilic transmural migration was found in several cases and 25 cases had acute perivasculitis. Paravascular microhemorrhages and petechial hemorrhages (small brain parenchymal hemorrhages) had a slight tendency to be more numerous in cohort cases that displayed less acute neutrophilic vasculitis. Tissue burden of acute neutrophilic vasculitis with leukocytoclasia was the same in control cases as a group, while it was significantly higher in COVID-19 cases. Both the tissue burden of acute neutrophilic vasculitis and the activation of complement components, including membrane attack complex, were significantly higher in microcirculatory channels in COVID-19 cohort brains than in historical controls.

CONCLUSIONS

Acute neutrophilic vasculitis with leukocytoclasia, acute perivasculitis, and associated paravascular blood extravasation into brain parenchyma constitute the first phase of an immune-related, acute small-vessel inflammatory condition often termed type 3 hypersensitivity vasculitis or leukocytoclastic vasculitis. There is a higher tissue burden of acute neutrophilic vasculitis and an increased level of activated complement components in microcirculatory walls in COVID-19 cases than in pre-pandemic control cases. These findings are consistent with a more extensive small-vessel immune-related vasculitis in COVID-19 cases than in control cases. The pathway(s) and mechanism for these findings are speculative.

Efficacy and safety of baricitinib or ravulizumab in adult patients with severe COVID-19 (TACTIC-R): a randomised, parallel-arm, open-label, phase 4 trial

BACKGROUND

From early in the COVID-19 pandemic, evidence suggested a role for cytokine dysregulation and complement activation in severe disease. In the TACTIC-R trial, we evaluated the efficacy and safety of baricitinib, an inhibitor of Janus kinase 1 (JAK1) and JAK2, and ravulizumab, a monoclonal inhibitor of complement C5 activation, as an adjunct to standard of care for the treatment of adult patients hospitalised with COVID-19.

METHODS

TACTIC-R was a phase 4, randomised, parallel-arm, open-label platform trial that was undertaken in the UK with urgent public health designation to assess the potential of repurposing immunosuppressants for the treatment of severe COVID-19, stratified by a risk score. Adult participants (aged ≥18 years) were enrolled from 22 hospitals across the UK. Patients with a risk score indicating a 40% risk of admission to an intensive care unit or death were randomly assigned 1:1:1 to standard of care alone, standard of care with baricitinib, or standard of care with ravulizumab. The composite primary outcome was the time from randomisation to incidence (up to and including day 14) of the first event of death, invasive mechanical ventilation, extracorporeal membrane oxygenation, cardiovascular organ support, or renal failure. The primary interim analysis was triggered when 125 patient datasets were available up to day 14 in each study group and we included in the analysis all participants who were randomly assigned. The trial was registered on ClinicalTrials.gov (NCT04390464).

FINDINGS

Between May 8, 2020, and May 7, 2021, 417 participants were recruited and randomly assigned to standard of care alone (145 patients), baricitinib (137 patients), or ravulizumab (135 patients). Only 54 (39%) of 137 patients in the baricitinib group received the maximum 14-day course, whereas 132 (98%) of 135 patients in the ravulizumab group received the intended dose. The trial was stopped after the primary interim analysis on grounds of futility. The estimated hazard ratio (HR) for reaching the composite primary endpoint was 1·11 (95% CI 0·62-1·99) for patients on baricitinib compared with standard of care alone, and 1·53 (0·88-2·67) for ravulizumab compared with standard of care alone. 45 serious adverse events (21 deaths) were reported in the standard-of-care group, 57 (24 deaths) in the baricitinib group, and 60 (18 deaths) in the ravulizumab group.

INTERPRETATION

Neither baricitinib nor ravulizumab, as administered in this study, was effective in reducing disease severity in patients selected for severe COVID-19. Safety was similar between treatments and standard of care. The short period of dosing with baricitinib might explain the discrepancy between our findings and those of other trials. The therapeutic potential of targeting complement C5 activation product C5a, rather than the cleavage of C5, warrants further evaluation.

FUNDING

UK Medical Research Council, UK National Institute for Health Research Cambridge Biomedical Research Centre, Eli Lilly and Company, Alexion Pharmaceuticals, and Addenbrooke's Charitable Trust.

Alveolar Hyperoxia and Exacerbation of Lung Injury in Critically Ill SARS-CoV-2 Pneumonia

Acute hypoxic respiratory failure (AHRF) is a prominent feature of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) critical illness. The severity of gas exchange impairment correlates with worse prognosis, and AHRF requiring mechanical ventilation is associated with substantial mortality. Persistent impaired gas exchange leading to hypoxemia often warrants the prolonged administration of a high fraction of inspired oxygen (FiO2). In SARS-CoV-2 AHRF, systemic vasculopathy with lung microthrombosis and microangiopathy further exacerbates poor gas exchange due to alveolar inflammation and oedema. Capillary congestion with microthrombosis is a common autopsy finding in the lungs of patients who die with coronavirus disease 2019 (COVID-19)-associated acute respiratory distress syndrome. The need for a high FiO2 to normalise arterial hypoxemia and tissue hypoxia can result in alveolar hyperoxia. This in turn can lead to local alveolar oxidative stress with associated inflammation, alveolar epithelial cell apoptosis, surfactant dysfunction, pulmonary vascular abnormalities, resorption atelectasis, and impairment of innate immunity predisposing to secondary bacterial infections. While oxygen is a life-saving treatment, alveolar hyperoxia may exacerbate pre-existing lung injury. In this review, we provide a summary of oxygen toxicity mechanisms, evaluating the consequences of alveolar hyperoxia in COVID-19 and propose established and potential exploratory treatment pathways to minimise alveolar hyperoxia.

Recombinant SARS-CoV-2 Spike Protein and Its Receptor Binding Domain Stimulate Release of Different Pro-Inflammatory Mediators via Activation of Distinct Receptors on Human Microglia Cells

SARS-CoV-2 infects cells via its spike (S) protein binding to its surface receptor angiotensin converting enzyme 2 (ACE2) on target cells and results in acute symptoms involving especially the lungs known as COVID-19. However, increasing evidence indicates that SARS-CoV-2 infection produces neuroinflammation associated with neurological, neuropsychiatric, and cognitive symptoms persists well past the resolution of the infection, known as post-COVID-19 sequalae or long-COVID. The neuroimmune mechanism(s) involved in long-COVID have not been adequately characterized. In this study, we show that recombinant SARS-CoV-2 full-length S protein stimulates release of pro-inflammatory IL-1b, CXCL8, IL-6, and MMP-9 from cultured human microglia via TLR4 receptor activation. Instead, recombinant receptor-binding domain (RBD) stimulates release of TNF-α, IL-18, and S100B via ACE2 signaling. These results provide evidence that SARS-CoV-2 spike protein contributes to neuroinflammation through different mechanisms that may be involved in CNS pathologies associated with long-COVID.

Central nervous system complications in SARS-CoV-2-infected patients

OBJECTIVE

To investigate the clinical manifestations, treatment and prognosis of COVID-19-associated central nervous system (CNS) complications.

METHODS

In this single-centre observation study, we recruited patients with COVID-19-associated CNS complications at the neurology inpatient department of the Eighth Affiliated Hospital, Sun Yat-Sen University (Futian, Shenzhen) from Dec 2022 to Feb 2023. Patients were analysed for demographics, clinical manifestations, cerebrospinal fluid properties, electroencephalographic features, neuroimaging characteristics, and treatment outcome. All patients were followed-up at 1 and 2 months after discharge until Apr 2023.

RESULTS

Of the 12 patients with COVID-19-associated CNS complications, the CNS symptoms occur between 0 days and 4 weeks after SARS-CoV-2 infection. The most common CNS symptoms were memory deficits (4/12, 33%), Unresponsiveness (4/12, 33%), mental and behavioural disorders (4/12, 33%). Seven of 12 cases can be categorized as probable SARS-CoV-2 encephalitis, and 5 cases can be described as brainstem encephalitis, acute disseminated encephalomyelitis, optic neuritis, multiple sclerosis or tremor probably associated with SARS-CoV-2 infection. Six patients received antiviral therapy, and 11 patients received glucocorticoid therapy, of which 3 patients received human immunoglobulin synchronously. Nine patients recovered well, two patients had residual neurological dysfunction, and one patient passed away from complications associated with tumor.

CONCLUSION

In this observational study, we found that the inflammatory or immune-related complications were relatively common manifestations of COVID-19-associated CNS complications, including different phenotypes of encephalitis and CNS inflammatory demyelinating diseases. Most patients recovered well, but a few patients had significant neurological dysfunctions remaining.

Long COVID could become a widespread post-pandemic disease? A debate on the organs most affected

Long COVID is an emerging problem in the current health care scenario. It is a syndrome with common symptoms of shortness of breath, fatigue, cognitive dysfunction, and other conditions that have a high impact on daily life. They are fluctuating or relapsing states that occur in patients with a history of SARS-CoV-2 infection for at least 2 months. They are usually conditions that at 3 months after onset cannot be explained by an alternative diagnosis. Currently very little is known about this syndrome. A thorough review of the literature highlights that the cause is attributable to deposits of tau protein. Massive phosphorylation of tau protein in response to SARS-CoV-2 infection occurred in brain samples from autopsies of people previously affected with COVID-19. The neurological disorders resulting from this clinical condition are termed tauopathies and can give different pathological symptoms depending on the involved anatomical region of the brain. Peripheral small-fiber neuropathies are also evident among patients with Long COVID leading to fatigue, which is the main symptom of this syndrome. Certainly more research studies could confirm the association between tau protein and Long COVID by defining the main role of tau protein as a biomarker for the diagnosis of this syndrome that is widespread in the post-pandemic period.

SARS-Cov-2 infection and neuropathological findings: a report of 18 cases and review of the literature

INTRODUCTION

COVID-19-infected patients harbour neurological symptoms such as stroke and anosmia, leading to the hypothesis that there is direct invasion of the central nervous system (CNS) by SARS-CoV-2. Several studies have reported the neuropathological examination of brain samples from patients who died from COVID-19. However, there is still sparse evidence of virus replication in the human brain, suggesting that neurologic symptoms could be related to mechanisms other than CNS infection by the virus. Our objective was to provide an extensive review of the literature on the neuropathological findings of postmortem brain samples from patients who died from COVID-19 and to report our own experience with 18 postmortem brain samples.

MATERIAL AND METHODS

We used microscopic examination, immunohistochemistry (using two different antibodies) and PCR-based techniques to describe the neuropathological findings and the presence of SARS-CoV-2 virus in postmortem brain samples. For comparison, similar techniques (IHC and PCR) were applied to the lung tissue samples for each patient from our cohort. The systematic literature review was conducted from the beginning of the pandemic in 2019 until June 1st, 2022.

RESULTS

In our cohort, the most common neuropathological findings were perivascular haemosiderin-laden macrophages and hypoxic-ischaemic changes in neurons, which were found in all cases (n = 18). Only one brain tissue sample harboured SARS-CoV-2 viral spike and nucleocapsid protein expression, while all brain cases harboured SARS-CoV-2 RNA positivity by PCR. A colocalization immunohistochemistry study revealed that SARS-CoV-2 antigens could be located in brain perivascular macrophages. The literature review highlighted that the most frequent neuropathological findings were ischaemic and haemorrhagic lesions, including hypoxic/ischaemic alterations. However, few studies have confirmed the presence of SARS-CoV-2 antigens in brain tissue samples.

CONCLUSION

This study highlighted the lack of specific neuropathological alterations in COVID-19-infected patients. There is still no evidence of neurotropism for SARS-CoV-2 in our cohort or in the literature.

Evaluation of the retina with optical coherence tomography angiography (OCTA) in patients with coronavirus (COVID-19) infection

PURPOSE

The goal of this study is to compare the optical coherence tomography angiography (OCTA) findings in Coronavirus (COVID-19) positive adult and pediatric patients with those of healthy volunteers with the same demographic characteristics.

METHODS

The right eye of 157 adults infected with covid, 168 healthy adult volunteers, 40 children (6-18 years of age) infected with covid, and 44 healthy children (6-18 years of age) were included in this prospective study. All participants underwent ophthalmological examination and OCTA. The OCTA findings were evaluated.

RESULTS

Deep nasal density (DND), deep inferior density (DID), and deep parafoveal density (DPD) were significantly lower in the pediatric covid-affected group (PCAG) than in the pediatric healthy control group (PHCG) (P=0.034, P=0.029, P=0.022 respectively). On the other hand, radial peripapillary capillary vessel density (RPCVD) intra-disc measurements were significantly higher in the PCAG compared to the PHCG (P=0.025). There was no significant difference between the OCTA measurements of the adult covid-affected group (ACAG) and the adult healthy control group (AHCG).

CONCLUSION

In our study, significant differences were found in OCTA measurements between the covid group and the healthy control group in children. Retinal microvascular changes may occur in patients with covid infection, and these patients might be followed for long-term retinal changes.

Receptors and Cofactors That Contribute to SARS-CoV-2 Entry: Can Skin Be an Alternative Route of Entry?

To prevent the spread of SARS-CoV-2, all routes of entry of the virus into the host must be mapped. The skin is in contact with the external environment and thus may be an alternative route of entry to transmission via the upper respiratory tract. SARS-CoV-2 cell entry is primarily dependent on ACE2 and the proteases TMPRSS2 or cathepsin L but other cofactors and attachment receptors have been identified that may play a more important role in specific tissues such as the skin. The continued emergence of new variants may also alter the tropism of the virus. In this review, we summarize current knowledge on these receptors and cofactors, their expression profile, factors modulating their expression and their role in facilitating SARS-CoV-2 infection. We discuss their expression in the skin and their possible involvement in percutaneous infection since the presence of the virus has been detected in the skin.

COVID-19 Associated Vasculitis Confirmed by the Tissues RT-PCR: A Case Series Report

Background: Several cases of skin and central nervous system vasculopathy associated with COVID-19 in children have been published, but the information is rather limited. Our study aimed to describe these cases of vasculitis associated with COVID-19 in children. Methods: In the retrospective-prospective case series study we included information regarding four children with COVID-19-associated vasculitis. In every case, we had a morphological description and the etiology was confirmed via real-time polymerase chain reaction during a tissue biopsy. Results: The most involved systems were skin (4/4), respiratory (3/4), cardiovascular (2/4), nervous (1/4), eye (1/4), kidney (1/4), and inner year (1/4). All patients had increased inflammatory markers and thrombotic parameters (D-dimer). No patient met the criteria for multisystem inflammatory syndrome in children. Two patients met polyarteritis nodosa criteria, one met Henoch–Schonlein purpura criteria, and one met unclassified vasculitis criteria. All patients were treated with systemic glucocorticosteroids (two-pulse therapy). Non-biologic DMARDs were prescribed in all cases; 1/4 patients (25%) was treated with intravenous immunoglobuline, and 3/4 (75%) were treated with biologics (etanercept, tocilizumab, and adalimumab). Conclusions: Vasculitis associated with COVID-19 could be a life-threatening condition; SARS-CoV-2 might be a new trigger or etiological agent for vasculitis and other immune-mediated diseases. Further research and collection of similar cases are required.

Role of SARS-CoV-2 Spike-Protein-Induced Activation of Microglia and Mast Cells in the Pathogenesis of Neuro-COVID

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). About 45% of COVID-19 patients experience several symptoms a few months after the initial infection and develop post-acute sequelae of SARS-CoV-2 (PASC), referred to as "Long-COVID," characterized by persistent physical and mental fatigue. However, the exact pathogenetic mechanisms affecting the brain are still not well-understood. There is increasing evidence of neurovascular inflammation in the brain. However, the precise role of the neuroinflammatory response that contributes to the disease severity of COVID-19 and long COVID pathogenesis is not clearly understood. Here, we review the reports that the SARS-CoV-2 spike protein can cause blood-brain barrier (BBB) dysfunction and damage neurons either directly, or via activation of brain mast cells and microglia and the release of various neuroinflammatory molecules. Moreover, we provide recent evidence that the novel flavanol eriodictyol is particularly suited for development as an effective treatment alone or together with oleuropein and sulforaphane (ViralProtek®), all of which have potent anti-viral and anti-inflammatory actions.

COVID-19 Vaccine-Associated Immune Thrombosis and Thrombocytopenia (VITT): Diagnostic Discrepancies and Global Implications

Vaccine-induced immune thrombotic thrombocytopenia (VITT) has been reported in association with the coronavirus disease 2019 preventative adenovirus vector-based vaccines ChAdOx1 nCoV-19 (Oxford/AstraZeneca) and Ad26.COV2.S (Janssen/Johnson & Johnson) in hundreds of recipients across the globe. VITT is characterized by thrombosis, typically at unusual sites, low fibrinogen, and elevated plasma D-dimer, generally manifesting between 4 and 28 days following vaccination. Detection of anti-platelet factor antibodies using an enzyme-linked immunosorbent assay (ELISA) is often confirmatory. Although several similar principles subside in most diagnostic criteria for VITT, the presentation of a positive ELISA assay, use of expert hematology and neurology opinion, and exclusion of possible VITT cases outside the "standard" 4 to 28-day timeframe have contributed a lack of global standardization for defining VITT. Accordingly, the global and regional incidence of VITT differs according to the diagnostic pathway and case definition used. This has influenced the public perception of VITT's severity and the decision to use adenovirus vector-based vaccines for limiting severe acute respiratory syndrome coronavirus 2 infection. We hereby delineate the recognized pathogenic mechanisms, global incidence, discrepancies in diagnostic criteria, recommended treatments, and global implications to vaccine hesitancy from this coagulopathy.

Microvascular significance of TGF-β axis activation in COVID-19

As 2023 approaches, the COVID-19 pandemic has killed millions. While vaccines have been a crucial intervention, only a few effective medications exist for prevention and treatment of COVID-19 in breakthrough cases or in unvaccinated or immunocompromised patients. SARS-CoV-2 displays early and unusual features of micro-thrombosis and immune dysregulation that target endothelial beds of the lungs, skin, and other organs. Notably, anticoagulation improves outcomes in some COVID-19 patients. The protein transforming growth factor-beta (TGF-β1) has constitutive roles in maintaining a healthy microvasculature through its roles in regulating inflammation, clotting, and wound healing. However, after infection (including viral infection) TGF-β1 activation may augment coagulation, cause immune dysregulation, and direct a path toward tissue fibrosis. Dysregulation of TGF-β signaling in immune cells and its localization in areas of microvascular injury are now well-described in COVID-19, and such events may contribute to the acute respiratory distress syndrome and skin micro-thrombosis outcomes frequently seen in severe COVID-19. The high concentration of TGF-β in platelets and in other cells within microvascular thrombi, its ability to activate the clotting cascade and dysregulate immune pathways, and its pro-fibrotic properties all contribute to a unique milieu in the COVID-19 microvasculature. This unique environment allows for propagation of microvascular clotting and immune dysregulation. In this review we summarize the physiological functions of TGF-β and detail the evidence for its effects on the microvasculature in COVID-19. In addition, we explore the potential role of existing TGF-β inhibitors for the prevention and treatment of COVID-19 associated microvascular thrombosis and immune dysregulation.

SARS-CoV-2 Spike protein activates TMEM16F-mediated platelet procoagulant activity

Thrombosis of the lung microvasculature is a characteristic of COVID-19 disease, which is observed in large excess compared to other forms of acute respiratory distress syndrome and thus suggests a trigger for thrombosis that is endogenous to the lung. Our recent work has shown that the SARS-CoV-2 Spike protein activates the cellular TMEM16F chloride channel and scramblase. Through a screening on >3,000 FDA/EMA approved drugs, we identified Niclosamide and Clofazimine as the most effective molecules at inhibiting Spike-induced TMEM16 activation. As TMEM16F plays an important role in stimulating the procoagulant activity of platelets, we investigated whether Spike directly affects platelet activation and pro-thrombotic function and tested the effect of Niclosamide and Clofazimine on these processes. Here we show that Spike, present either on the virion envelope or on the cell plasma membrane, promotes platelet activation, adhesion and spreading. Spike was active as a sole agonist or, even more effectively, by enhancing the function of known platelet activators. In particular, Spike-induced a marked procoagulant phenotype in platelets, by enhancing Ca²⁺ flux, phosphatidylserine externalization on the platelet outer cell membrane, and thrombin generation. Eventually, this increased thrombin-induced clot formation and retraction. Both Niclosamide and Clofazimine blocked this Spike-induced procoagulant response. These findings provide a pathogenic mechanism to explain lung thrombosis-associated with severe COVID-19 infection. We propose that Spike, present in SARS-CoV-2 virions or exposed on the surface of infected cells in the lungs, enhances the effects of inflammation and leads to local platelet stimulation and subsequent activation of the coagulation cascade. As platelet TMEM16F is central in this process, these findings reinforce the rationale of repurposing Niclosamide for COVID-19 therapy.

Association of Ang/Tie2 pathway mediators with endothelial barrier integrity and disease severity in COVID-19

Endothelial barrier (EB) disruption contributes to acute lung injury in COVID-19, and levels of both VEGF-A and Ang-2, which are mediators of EB integrity, have been associated with COVID-19 severity. Here we explored the participation of additional mediators of barrier integrity in this process, as well as the potential of serum from COVID-19 patients to induce EB disruption in cell monolayers. In a cohort from a clinical trial consisting of thirty patients with COVID-19 that required hospital admission due to hypoxia we demonstrate that i) levels of soluble Tie2 were increase, and of soluble VE-cadherin were decreased when compared to healthy individuals; ii) sera from these patients induce barrier disruption in monolayers of endothelial cells; and iii) that the magnitude of this effect is proportional to disease severity and to circulating levels of VEGF-A and Ang-2. Our study confirms and extends previous findings on the pathogenesis of acute lung injury in COVID-19, reinforcing the concept that EB is a relevant component of this disease. Our results pave the way for future studies that can refine our understanding of the pathogenesis of acute lung injury in viral respiratory disorders, and contribute to the identification of new biomarkers and therapeutic targets for these conditions.

[Psychological, psychiatric and neurological aspects of COVID-19]

OBJECTIVE

To analyze neurological, psychological and psychiatric aspects of COVID-19, as well as to study the current state of the problem.

MATERIAL AND METHODS

The study included 103 patients with COVID-19. The main research method was clinical/psychopathological. To study the impact of activities related to the care of patients with COVID-19 in a hospital setting, the medical and psychological state of 197 hospital workers involved in the treatment of patients with COVID-19 was assessed. The level of anxiety distress was assessed with the Psychological Stress Scale (PSM-25), distress indicators corresponded to values of more than 100 points. The severity of anxiety and depressive symptoms was assessed using the Hospital Anxiety and Depression Scale (HADS).

RESULTS

When considering psychopathological disorders in the context of COVID-19, it is necessary to distinguish between two main groups of disorders: mental disorders during the pandemic, and mental disorders directly caused by the causative agent SARS-CoV-2. The analysis of psychological and psychiatric aspects in various periods of the initial stage of COVID-19 showed that each of them was characterized by specific features depending on the nature of the influence of different pathogenic factors. In the structure of nosogenic mental disorders in patients with COVID-19 (103 patients), the following clinical forms were identified: acute reaction to stress (9.7%), anxiety-phobic disorders (41.7%), depressive symptoms (28.1%), hyponosognosic nosogenic reactions (20.5%). At the same time, the majority of the patients had manifestations of somatogenic asthenia (93.2%). A comparative analysis of neurological and psychological/psychiatric aspects of COVID-19 showed that the main mechanisms of the impact of highly contagious coronaviruses, including the SARS-CoV-2, on the central nervous system are: cerebral thrombosis and cerebral thromboembolism, damage to the neurovascular unit, neurodegeneration, including that induced by cytokines, and immune-mediated demyelinating nerve damage.

CONCLUSION

Neurological and psychological/psychiatric aspects of COVID-19 should be taken into account both at the stage of disease treatment and in the post-infection period due to the pronounced neurotropism of SARS-CoV-2 and its effect on the neurovascular unit. Along with helping patients, an important aspect is the preservation of the mental health of medical personnel working in hospitals for infectious diseases, due to special working conditions and a high level of professional stress.

The pathogenesis of coronavirus-19 disease

Severe acute respiratory syndrome-associated coronavirus-2 (SARS-CoV-2) is the causal agent of coronavirus disease-2019 (COVID-19), a systemic illness characterized by variably severe pulmonary symptoms, cardiac conduction abnormalities, diarrhea, and gastrointestinal bleeding, as well as neurologic deficits, renal insufficiency, myalgias, endocrine abnormalities, and other perturbations that reflect widespread microvascular injury and a pro-inflammatory state. The mechanisms underlying the various manifestations of viral infection are incompletely understood but most data suggest that severe COVID-19 results from virus-driven perturbations in the immune system and resultant tissue injury. Aberrant interferon-related responses lead to alterations in cytokine elaboration that deplete resident immune cells while simultaneously recruiting hyperactive macrophages and functionally altered neutrophils, thereby tipping the balance from adaptive immunity to innate immunity. Disproportionate activation of these macrophages and neutrophils further depletes normal activity of B-cells, T-cells, and natural killer (NK) cells. In addition, this pro-inflammatory state stimulates uncontrolled complement activation and development of neutrophil extracellular traps (NETS), both of which promote the coagulation cascade and induce a state of “thrombo-inflammation”. These perturbations have similar manifestations in multiple organ systems, which frequently show pathologic findings related to microvascular injury and thrombosis of large and small vessels. However, the pulmonary findings in patients with severe COVID-19 are generally more pronounced than those of other organs. Not only do they feature inflammatory thromboses and endothelial injury, but much of the parenchymal damage stems from failed maturation of alveolar pneumocytes, interactions between type 2 pneumocytes and non-resident macrophages, and a greater degree of NET formation. The purpose of this review is to discuss the pathogenesis underlying organ damage that can occur in patients with SARS-CoV-2 infection. Understanding these mechanisms of injury is important to development of future therapies for patients with COVID-19, many of which will likely target specific components of the immune system, particularly NET induction, pro-inflammatory cytokines, and subpopulations of immune cells.

Plant polysaccharides with anti-lung injury effects as a potential therapeutic strategy for COVID-19

When coronavirus disease 2019 (COVID-19) develops into the severe phase, lung injury, acute respiratory distress syndrome, and/or respiratory failure could develop within a few days. As a result of pulmonary tissue injury, pathomorphological changes usually present endothelial dysfunction, inflammatory cell infiltration of the lung interstitium, defective gas exchange, and wall leakage. Consequently, COVID-19 may progress to tremendous lung injury, ongoing lung failure, and death. Exploring the treatment drugs has important implications. Recently, the application of traditional Chinese medicine had better performance in reducing fatalities, relieving symptoms, and curtailing hospitalization. Through constant research and study, plant polysaccharides may emerge as a crucial resource against lung injury with high potency and low side effects. However, the absence of a comprehensive understanding of lung-protective mechanisms impedes further investigation of polysaccharides. In the present article, a comprehensive review of research into plant polysaccharides in the past 5 years was performed. In total, 30 types of polysaccharides from 19 kinds of plants have shown lung-protective effects through the pathological processes of inflammation, oxidative stress, apoptosis, autophagy, epithelial–mesenchymal transition, and immunomodulation by mediating mucin and aquaporins, macrophage, endoplasmic reticulum stress, neutrophil, TGF-β1 pathways, Nrf2 pathway, and other mechanisms. Moreover, the deficiencies of the current studies and the future research direction are also tentatively discussed. This research provides a comprehensive perspective for better understanding the mechanism and development of polysaccharides against lung injury for the treatment of COVID-19.

Association between Renal Function at Admission and COVID-19 in-Hospital Mortality in Southern Italy: Findings from the Prospective Multicenter Italian COVOCA Study

Background. Evidence has shown a close association between COVID-19 infection and renal complications in both individuals with previously normal renal function and those with chronic kidney disease (CKD). Methods. The aim of this study is to evaluate the in-hospital mortality of SARS-CoV-2 patients according to their clinical history of CKD or estimated glomerular filtration rate (eGFR). This is a prospective multicenter observational cohort study which involved adult patients (≥18 years old) who tested positive with SARS-CoV-2 infection and completed their hospitalization in the period between November 2020 and June 2021. Results. 1246 patients were included in the study, with a mean age of 64 years (SD 14.6) and a median duration of hospitalization of 15 days (IQR 9−22 days). Cox’s multivariable regression model revealed that mortality risk was strongly associated with the stage of renal impairment and the Kaplan−Meier survival analysis showed a progressive and statistically significant difference (p < 0.0001) in mortality according to the stage of CKD. Conclusion. This study further validates the association between CKD stage at admission and mortality in patients hospitalized for COVID-19. The risk stratification based on eGFR allows clinicians to identify the subjects with the highest risk of intra-hospital mortality despite the duration of hospitalization.

The amplification of CNS damage in Alzheimer's disease due to SARS-CoV2 infection

Pre-existing Alzheimer's disease is a risk factor for severe/fatal COVID-19 and infection by SARS-CoV2 virus has been associated with an increased incidence of un-masked Alzheimer's disease. The molecular basis whereby SARS-CoV2 may amplify Alzheimer's disease is not well understood. This study analyzed the molecular changes in autopsy brain tissues from people with pre-existing dementia who died of COVID-19 (n = 5) which was compared to equivalent tissues of people who died of COVID-19 with no history of dementia (n = 8), Alzheimer's disease pre-COVID-19 (n = 10) and aged matched controls (n = 10) in a blinded fashion. Immunohistochemistry analyses for hyperphosphorylated tau protein, α-synuclein, and β-amyloid-42 confirmed the diagnoses of Alzheimer's disease (n = 4), and Lewy body dementia (n = 1) in the COVID-19 group. The brain tissues from patients who died of COVID-19 with no history of dementia showed a diffuse microangiopathy marked by endocytosis of spike subunit S1 and S2 in primarily CD31+ endothelia with strong co-localization with ACE2, Caspase-3, IL6, TNFα, and Complement component 6 that was not associated with SARS-CoV2 RNA. Microglial activation marked by increased TMEM119 and MCP1 protein expression closely paralleled the endocytosed spike protein. The COVID-19 tissues from people with no pre-existing dementia showed, compared to controls, 5-10× fold increases in expression of neuronal NOS and NMDAR2 as well as a marked decrease in the expression of proteins whose loss is associated with worsening Alzheimer's disease: MFSD2a, SHIP1, BCL6, BCL10, and BACH1. In COVID-19 tissues from people with dementia the widespread spike-induced microencephalitis with the concomitant microglial activation co-existed in the same areas where neurons had hyperphosphorylated tau protein suggesting that the already dysfunctional neurons were additionally stressed by the SARS-CoV2 induced microangiopathy. ACE2+ human brain endothelial cells treated with high dose (but not vaccine equivalent low dose) spike S1 protein demonstrated each of the molecular changes noted in the in vivo COVID-19 and COVID-19/Alzheimer's disease brain tissues. It is concluded that fatal COVID-19 induces a diffuse microencephalitis and microglial activation in the brain due to endocytosis of circulating viral spike protein that amplifies pre-existing dementia in at least two ways: 1) modulates the expression of proteins that may worsen Alzheimer's disease and 2) stresses the already dysfunctional neurons by causing an acute proinflammatory/hypercoagulable/hypoxic microenvironment in areas with abundant hyperphosphorylated tau protein and/or βA-42.

Vestibular disorders in patients after COVID-19 infection

Introduction

The COVID-19 clinical symptoms are primarily related to the respiratory system but may also be involved in many others, including the nervous system. Recently, vertigo or dizziness has been described as one of the clinical manifestations and possible complications of COVID-19.

Materials and methods

This clinical study was designed to describe the otorhinolaryngological evaluation and videonystagmographic (VNG) findings in patients with an antecedent of COVID-19 infection in the last 6 months. In this study, we sought to investigate the presence of persistent vestibular damage in healed COVID-19 patients and to determine the origin of vertigo by conducting a comprehensive vestibular examination. To evaluate the association precisely, an otoneurological assessement was conducted on all participants. The study group included 58 patients aged 23–75 years with vertigo, who were diagnosed with COVID-19 infection 6 months before the examination. Each participant was submitted to an evaluation consisting of anamnesis, otorhinolaryngological evaluation, and VNG.

Results

Spontaneous nystagmus with closed eyes was reported in 8 patients (13.8%). Positional nystagmus was observed in 15 patients (24.1%). Asymmetrical optokinetic nystagmus was observed in 18 patients (31%). A distorted record in the tracking pendulum test was present in 23 patients (39.7%). Square waves were observed in 34 COVID-19 patients (58.6%). Unilateral weakness (UW) was observed in 23 subjects (39.7%); among those with UW, 22 patients (95.7%) also demonstrated directional preponderance contralateral to the UW. Another 16 patients (27.6%) presented only directional advantage. The post-caloric recruitment was present in 38% patients.

Conclusion

Patients who had been diagnosed with COVID-19 seem to be more likely to suffer from vertigo/dizziness and to compensate more slowly. COVID-19 infection may cause inner ear damage and lead to vestibular dysfunction. The role of the central nervous system in the onset of equilibrium disorders should be considered. The presence of vertigo of central origin may indicate the neurotropic effect of SARS-CoV-2 following COVID-19. Imbalance may be the only symptom of COVID-19 and may also be a late complication of the disease due to post-infectious inflammation of the nervous tissue. Comprehensive studies are needed to investigate whether COVID-19 can cause long-term vestibular deficits.

Cerebral microvascular injuries in severe COVID-19 infection: progression of white matter hyperintensities post-infection

A range of neuroradiological findings has been reported in patients with COVID-19, some mimicking cerebral small vessel disease (CSVD). We present a case of a man in his 50s with severe COVID-19, who was Glasgow Coma Scale 3 and tetraparetic after sedation was ceased in the intensive care unit. Return of consciousness and motor activity was slow. An MRI 1 month after debut of symptoms demonstrated white matter hyperintensities on T2-weighted Fluid Attenuated Inversion Recovery (T2-FLAIR) and many small areas with impaired diffusion in primarily supratentorial and infratentorial white matter on Diffusion-Weighted Imaging (DWI). In the following months, the patient made a remarkable clinical recovery. Despite clinical improvement, an MRI after 7 months showed that white matter hyperintensities had progressed and become confluent. Both MRIs demonstrated findings resembling CSVD, which could relate to a COVID-19-specific process affecting cerebral microvasculature.

SARS-CoV-2 and Skin: New Insights and Perspectives

The SARS-CoV-2 pandemic has disrupted global health systems and brought the entire globe to its knees. Although born as a disease of the respiratory system, COVID-19 can affect different parts of the body, including the skin. Reports of ongoing skin manifestations of COVID-19 have gradually multiplied, pushing researchers to investigate the etiopathogenic mechanisms underlying these phenomena in more depth. In an attempt to investigate the possible association between SARS-CoV-2, ACE2, TMPRSS2 and skin manifestations, we performed immunohistochemical investigations of the ACE2 receptor and TMPRSS2 in nine skin samples from SARS-CoV-2-positive patients compared to a cohort of healthy controls. Furthermore, after consulting public databases regarding ACE2 mRNA expression in various cell populations resident in the skin, we conducted a literature review aimed at outlining the current state of this topic. We did not find statistically different immuno-expression of ACE2 and TMPRSS2 between the group of SARS-CoV-2-positive patients (nine skin biopsies) and the control group. Regarding ACE2, major immunolabeling was present in the epidermal keratinocytes and, rarely, in the fibroblasts and in the adenomeres of the eccrine sweat glands. Regarding the immune expression of TMPRSS2, we found no significant differences between the two groups, with a weak immune staining only in some skin cytotypes. From the review of the literature, we isolated 35 relevant articles according to the inclusion criteria adopted. ACE2 appears to be a target of SARS-CoV-2, although, other receptor molecules may potentially be implicated, such as TMPRSS2. Future studies with large cases and different molecular investigative methods are needed to further elucidate the mechanisms underlying the skin manifestations of SARS-CoV-2.

The SARS-CoV-2 envelope protein disrupts barrier function in an in vitro human blood-brain barrier model

Patients with coronavirus disease 2019 (COVID-19) have been frequently reported to exhibit neurological manifestations and disruption of the blood-brain barrier (BBB). Among the risk factors for BBB breakdown, the loss of endothelial cells and pericytes has caused widespread concern. Recent studies have revealed that severe acute respiratory syndrome coronavirus 2 envelope (S2E) protein caused cell death. We tested the hypothesis that the S2E protein alone could induce BBB dysfunction. The S2E protein bound to human BBB-related cells and inhibited cell viability in a dose- and time-dependent manner. Importantly, the S2E protein disrupted barrier function in an in vitro BBB model composed of HCMEC/D3 (brain endothelial cell line), HBVP (brain vascular pericyte), and U87MG (astrocyte cell line) cells and suppressed the expression of major genes involved in maintaining endothelial permeability and function. In addition, the S2E protein crossed the HCMEC/D3 monolayer. The S2E protein triggered inflammatory responses in HCMEC/D3 and U87MG cells. Taken together, these results show for the first time that the S2E protein has a negative impact on the BBB. Therapies targeting the S2E protein could protect against and treat central nervous system manifestations in COVID-19 patients.

Perspective: The Case for Acute Large Vessel Ischemic Stroke in COVID-19 Originating Within Thrombosed Pulmonary Venules

The main burden of SARS-CoV-2 falls on the lungs but neurological manifestations, the most disabling of which are strokes and which correlate with disease severity, are common. We proffer a novel mechanism for acute COVID-19 stroke whereby pulmonary vein clots developing within the characteristic pulmonary intravascular thrombotic lesions can embolize to the brain. Appreciation of this mechanism requires an understanding of the tricompartmental model of lung parenchyma oxygenation (the alveolus, the bronchial artery, and the pulmonary artery), all of which are compromised in COVID-19. Of these 3 sources, the bronchial artery plays a crucial role in COVID-19 stroke because the unique collaterals from bronchial artery to pulmonary vein which exist under normal physiological conditions (and which maintain venous patency when the pulmonary artery is blocked by embolus) are occluded, thus leading to venular thrombosis in the presence of hypercoagulability. Dislodgement of clots from this source translocates the pathology to the brain and is a disease mechanism, formerly rare, which may account for many cases of large vessel occlusion stroke in COVID-19. This mechanism extends the concept of cardioembolic stroke from endocardium retrogradely into the pulmonary circulation with which the left cardiac chambers lie in direct continuity, and which is an accepted stroke mechanism under other circumstances such as lung lobectomy, where surgical ligation of the pulmonary vein creates a blind sac from which thrombi can embolize. The proposed model is supported by postmortem studies which have demonstrated venular thrombosis and by case reports of pulmonary vein thrombosis in COVID-19. This concept provides a more plausible cause for COVID-19 associated large vessel occlusion stroke than other putative mechanisms, such as cerebral endotheliitis, cytokine storm, and hypercoagulopathy, although it is acknowledged that the latter mechanism contributes to the genesis of pulmonary vein clots. Recognizing that extrapulmonary manifestations including stroke arise within thrombosed pulmonary veins is key to understanding of neurological manifestations of SARS-CoV-2 infection.

Retinal Microvascular Changes in COVID-19 Bilateral Pneumonia Based on Optical Coherence Tomography Angiography

The purpose of this study was to evaluate retinal and choroidal microvascular alterations with optical coherence tomography angiography (OCTA) in COVID-19 patients hospitalized because of bilateral pneumonia caused by SARS-CoV-2. The vessel density (VD) and foveal avascular zone (FAZ) of 63 patients with SARS-CoV-2 pneumonia who had positive polymerase chain reaction (PCR) tests and who recovered after receiving treatment and 45 healthy age- and gender-matched controls were evaluated and compared using OCTA in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). The VD was also estimated in both groups in the choriocapillaris (CC). In COVID-19 patients, there was a statistically significant difference between the patients and a control group in both superficial (FAZs) and deep (FAZd) avascular zone (p = 0.000). The VD was significantly lower in the foveal area in choriocapillaris (p = 0.046). There were no statistically significant changes in the VD in the superior, inferior, nasal, and temporal quadrants in superficial and deep plexus, or in the choriocapillaris. The VD was not significantly lower in the foveal area in superficial or deep plexus. COVID-19 may affect the retinal vasculature, causing ischemia, enlargement of the FAZ, and lowering of the VD in the choriocapillaris area. Routine ophthalmic examination after SARS-CoV-2 infection should be considered in the course of post-infectious rehabilitation.

Sensorineural Hearing Loss Post-COVID-19 Infection: An Update

The course of COVID-19 infection may be complicated by a variety of neurological manifestations. Since the inner ear is vulnerable to viruses, sensorineural hearing loss (SNHL) has been reported to occur following the SARS-CoV-2 infection, often resulting in long-term morbidity and worsening the quality of life. The interest in how the virus affects the inner ear has gradually increased since the pandemic’s spread, but little is still known about the SNHL potentially caused by SARS-CoV-2. The aim of this paper is to evaluate the possible association between SNHL and COVID-19 infection, through a systematic literature review. Currently available data suggest that SARS-CoV-2 may hamper cochlear function; however, available reports are still limited. Large cohort and prospective studies are necessary to evaluate the long-term effects of this viral infection in the inner ear.

Upregulating Human Cathelicidin Antimicrobial Peptide LL-37 Expression May Prevent Severe COVID-19 Inflammatory Responses and Reduce Microthrombosis

COVID-19 is characterized by hyperactivation by inflammatory cytokines and recruitment of macrophages, neutrophils, and other immune cells, all hallmarks of a strong inflammatory response that can lead to severe complications and multi-organ damage. Mortality in COVID-19 patients is associated with a high prevalence of neutrophil extracellular trap (NET) formation and microthrombosis that are exacerbated by hyperglycemia, diabetes, and old age. SARS-CoV-2 infection in humans and non-human primates have revealed long-term neurological consequences of COVID-19, possibly concomitant with the formation of Lewy bodies in the brain and invasion of the nervous system via the olfactory bulb. In this paper, we review the relevance of the human cathelicidin LL-37 in SARS-CoV-2 infections. LL-37 is an immunomodulatory, host defense peptide with direct anti-SARS-CoV-2 activity, and pleiotropic effects on the inflammatory response, neovascularization, Lewy body formation, and pancreatic islet cell function. The bioactive form of vitamin D and a number of other compounds induce LL-37 expression and one might predict its upregulation, could reduce the prevalence of severe COVID-19. We hypothesize upregulation of LL-37 will act therapeutically, facilitating efficient NET clearance by macrophages, speeding endothelial repair after inflammatory tissue damage, preventing α-synuclein aggregation, and supporting blood-glucose level stabilization by facilitating insulin release and islet β-cell neogenesis. In addition, it has been postulated that LL-37 can directly bind the S1 domain of SARS-CoV-2, mask angiotensin converting enzyme 2 (ACE2) receptors, and limit SARS-CoV-2 infection. Purposeful upregulation of LL-37 could also serve as a preventative and therapeutic strategy for SARS-CoV-2 infections.

COVID-19 Vasculitis and vasculopathy-Distinct immunopathology emerging from the close juxtaposition of Type II Pneumocytes and Pulmonary Endothelial Cells

The SARS-CoV-2 virus ACE-2 receptor utilization for cellular entry and the defined ACE-2 receptor role in cardiovascular medicine hinted at dysregulated endothelial function or even direct viral endotheliitis as the key driver of severe COVID-19 vascular immunopathology including reports of vasculitis. In this article, we critically review COVID-19 immunopathology from the vasculitis perspective and highlight the non-infectious nature of vascular endothelial involvement in severe COVID-19. Whilst COVID-19 lung disease pathological changes included juxta-capillary and vascular macrophage and lymphocytic infiltration typical of vasculitis, we review the evidence reflecting that such “vasculitis” reflects an extension of pneumonic inflammatory pathology to encompass these thin-walled vessels. Definitive, extrapulmonary clinically discernible vasculitis including cutaneous and cardiac vasculitis also emerged- namely a dysregulated interferon expression or “COVID toes” and an ill-defined systemic Kawasaki-like disease. These two latter genuine vasculitis pathologies were not associated with severe COVID-19 pneumonia. This was distinct from cutaneous vasculitis in severe COVID-19 that demonstrated pauci-immune infiltrates and prominent immunothrombosis that appears to represent a novel immunothrombotic vasculitis mimic contributed to by RNAaemia or potentially diffuse pulmonary venous tree thrombosis with systemic embolization with small arteriolar territory occlusion, although the latter remains unproven. Herein, we also performed a systematic literature review of COVID-19 vasculitis and reports of post-SARS-CoV-2 vaccination related vasculitis with respect to the commonly classified pre-COVID vasculitis groupings. Across the vasculitis spectrum, we noted that Goodpasture’s syndrome was rarely linked to natural SARS-CoV-2 infection but not vaccines. Both the genuine vasculitis in the COVID-19 era and the proposed vasculitis mimic should advance the understanding of both pulmonary and systemic vascular immunopathology.

Coagulopathy and Fibrinolytic Pathophysiology in COVID-19 and SARS-CoV-2 Vaccination

Coronavirus Disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is frequently complicated by thrombosis. In some cases of severe COVID-19, fibrinolysis may be markedly enhanced within a few days, resulting in fatal bleeding. In the treatment of COVID-19, attention should be paid to both coagulation activation and fibrinolytic activation. Various thromboses are known to occur after vaccination with SARS-CoV-2 vaccines. Vaccine-induced immune thrombotic thrombocytopenia (VITT) can occur after adenovirus-vectored vaccination, and is characterized by the detection of anti-platelet factor 4 antibodies by enzyme-linked immunosorbent assay and thrombosis in unusual locations such as cerebral venous sinuses and visceral veins. Treatment comprises high-dose immunoglobulin, argatroban, and fondaparinux. Some VITT cases show marked decreases in fibrinogen and platelets and marked increases in D-dimer, suggesting the presence of enhanced-fibrinolytic-type disseminated intravascular coagulation with a high risk of bleeding. In the treatment of VITT, evaluation of both coagulation activation and fibrinolytic activation is important, adjusting treatments accordingly to improve outcomes.

Investigation of CYP2E1 and Caspase-3 Gene Expressions in COVID-19 patients

Background

COVID-19 pandemic spread around the world like an infectious disease that presents waved effects on patients. Some patients needed ICU and respiratory support. Some patients only had flu-like symptoms. Cytokine storm and elevated ROS were serious problems for treatment. Apoptotic genes and CYP Family are part of these mechanisms.

Aim

In this study, our aim was to examine the gene expression CYP2E1 and Caspase-3 in patients with COVID-19 infection.

Method

60 COVID-19(+) patients (ICU and non-ICU patients) and 30 healthy volunteers were enrolled to study. To measure the level of gene expression qPCR was used. The 2-ΔΔCt method was utilized to analyze gene expression.

Results

The expression of CYP2E1 and Caspase-3 genes showed a significant discrepancy between patients and healthy individuals. Caspase-3 expression increased (p=0,0041) but CYP2E1 expression decreased (p=0,0214) in COVID-19 patients compared to healthy individuals. Both levels of gene expression were lower in patients with affected lungs than patients with unaffected lungs (p<0,05). Laboratory findings including d-Dimer, LDH, platelet count, lymphocyte count were related to both gene expressions (p<0,05). We found no correlation between CYP2E1 and Caspase-3 expressions.

Conclusion

The expression of Caspase-3 demonstrated apoptotic situations of patients but was not related to the CYP2E1 expression level. CYP2E1 gene expression is an important actor to metabolize endogens and xenobiotics however, COVID-19 patients demonstrated decreased CYP2E1 expression. CYP2E1 and Caspase-3 gene expression levels may be used as a diagnostic tool for COVID-19 patients.

Impaired Microvascular Function in Patients With Critical COVID-19

OBJECTIVES:

Severe coronavirus disease 2019 is characterized by infected microvascular endothelial cells. The primary aim of this study was to investigate microvascular function in patients with critical coronavirus disease 2019.

DESIGN:

A prospective observational study was conducted in which patients with critical and severe COVID-19 were investigated during acute disease phase and at least 3 months after disease onset.

SETTING:

Single-center study at Danderyd University Hospital.

PATIENTS:

Twenty-three patients with critical coronavirus disease 2019 treated with noninvasive or invasive mechanical ventilation, seven patients with severe COVID-19 with dyspnea or need of oxygen supply up to 8 L/min, and 15 noncoronavirus disease controls.

INTERVENTIONS:

None.

MEASUREMENTS:

Skin perfusion was investigated through laser speckle contrast imaging before and after iontophoresis of acetylcholine and sodium nitroprusside for determination of the endothelial-dependent and the endothelial-independent vasodilation, respectively.

MAIN RESULTS:

Patients with critical COVID-19 had higher basal skin perfusion during both the acute (34 ± 9 perfusion unit; p = 0.0003) and the postinfectious phase (29 ± 8 perfusion unit; p = 0.04), compared with noncoronavirus disease controls (23 ± 7 perfusion unit). In addition, endothelial-dependent and endothelial-independent vasodilation were reduced in patients with critical COVID-19 during the acute disease phase (p < 0.001 for both), whereas no significant differences between patients and controls were found during the postinfectious phase. In patients with severe COVID-19, basal skin perfusion and endothelial-dependent vasodilatation were not significantly changed, whereas endothelial-independent vasodilatation was reduced (p = 0.02) compared with controls.

CONCLUSIONS:

Changes in skin microcirculation in patients with critical COVID-19 indicate that the infection induces a systemic microvascular impairment with persisting long-term effects on the microvascular function.

Pneumonie à Sars-CoV-2 : broncho-pneumonie ou vasculopathie ? Focus sur le signe scanographique du « vaisseau élargi » et corrélations radio-histologiques

Introduction

La pandémie de Sars-CoV-2 évolue depuis un an et, à ce jour, la physiopathologie des lésions engendrées par cette atteinte virale n’est que partiellement élucidée. Le scanner thoracique est un outil diagnostique et pronostique essentiel de la prise en charge des patients et les lésions typiques de la pneumonie à Sars-CoV-2 sont à présent bien établies. Cependant, certaines anomalies vasculaires rencontrées chez la plupart des patients, qui se traduisent par un aspect épaissi et irrégulier des vaisseaux pulmonaires au sein des zones pathologiques, sont sous-estimées et peu connues des radiologues.

Données récentes

Les études histologiques soulignent la prépondérance des atteintes pariétales vasculaires au niveau pulmonaire qui peuvent être corrélées aux anomalies scanographiques. Ces dernières permettent d’orienter le diagnostic en cas de doute biologique ou de progression des lésions en verre dépoli. Elles suggèrent que l’atteinte alvéolo-interstitielle, sans anomalie bronchique ou bronchiolaire associée, pourrait être secondaire aux lésions vasculaires. Enfin, des études complémentaires sont nécessaires pour rechercher un éventuel intérêt pronostique de la quantification de ces lésions.

Conclusion

Ce travail illustre les corrélations radio-histologiques des atteintes vasculaires et pulmonaires du Sars-Cov-2 et propose une iconographie didactique des principales lésions rencontrées.

Variable levels of spike and ORF1ab RNA in post-mortem lung samples of SARS-CoV-2-positive subjects: comparison between ISH and RT-PCR

Post-mortem examination plays a pivotal role in understanding the pathobiology of the SARS-CoV-2; thus, the optimization of virus detection on the post-mortem formalin-fixed paraffin-embedded (FFPE) tissue is needed. Different techniques are available for the identification of the SARS-CoV-2, including reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry (IHC), in situ hybridization (ISH), and electron microscopy. The main goal of this study is to compare ISH versus RT-PCR to detect SARS-CoV-2 on post-mortem lung samples of positive deceased subjects. A total of 27 samples were analyzed by RT-PCR targeting different viral RNA sequences of SARS-CoV-2, including envelope (E), nucleocapsid (N), spike (S), and open reading frame (ORF1ab) genes and ISH targeting S and Orf1ab. All 27 cases showed the N gene amplification, 22 out of 27 the E gene amplification, 26 out of 27 the S gene amplification, and only 6 the ORF1ab gene amplification. The S ISH was positive only in 12 out of 26 cases positive by RT-PCR. The S ISH positive cases with strong and diffuse staining showed a correlation with low values of the number of the amplification cycles by S RT-PCR suggesting that ISH is a sensitive assay mainly in cases carrying high levels of S RNA. In conclusion, our findings demonstrated that ISH assay has lower sensitivity to detect SARS-CoV-2 in FFPE compared to RT-PCR; however, it is able to localize the virus in the cellular context since it preserves the morphology.

COVID-19-positivity in a heart transplant recipient—antibody-mediated rejection or SARS-CoV-2-associated cardiac injury?

Through the ongoing and heightening coronavirus disease 2019 (COVID-19) pandemic, the heart has been implicated as a central target of injury associated with significantly increased morbidity and mortality. Correspondingly, heart transplant recipients are a vulnerable population for which insufficient research has been conducted. Pathologic antibody-mediated rejection (pAMR) of cardiac allografts shares many characteristics with COVID-19-associated cardiac injury. In this case study, we investigate a 57-year-old female who contracted COVID-19 11 days postheart transplant and was observed to have pAMR while positive for laboratory-confirmed COVID-19, resulting in a diagnostic conundrum.

Could SARS-CoV-2 Spike Protein Be Responsible for Long-COVID Syndrome?

SARS-CoV-2 infects cells via its spike protein binding to its surface receptor on target cells and results in acute symptoms involving especially the lungs known as COVID-19. However, increasing evidence indicates that many patients develop a chronic condition characterized by fatigue and neuropsychiatric symptoms, termed long-COVID. Most of the vaccines produced so far for COVID-19 direct mammalian cells via either mRNA or an adenovirus vector to express the spike protein, or administer recombinant spike protein, which is recognized by the immune system leading to the production of neutralizing antibodies. Recent publications provide new findings that may help decipher the pathogenesis of long-COVID. One paper reported perivascular inflammation in brains of deceased patients with COVID-19, while others showed that the spike protein could damage the endothelium in an animal model, that it could disrupt an in vitro model of the blood-brain barrier (BBB), and that it can cross the BBB resulting in perivascular inflammation. Moreover, the spike protein appears to share antigenic epitopes with human molecular chaperons resulting in autoimmunity and can activate toll-like receptors (TLRs), leading to release of inflammatory cytokines. Moreover, some antibodies produced against the spike protein may not be neutralizing, but may change its conformation rendering it more likely to bind to its receptor. As a result, one wonders whether the spike protein entering the brain or being expressed by brain cells could activate microglia, alone or together with inflammatory cytokines, since protective antibodies could not cross the BBB, leading to neuro-inflammation and contributing to long-COVID. Hence, there is urgent need to better understand the neurotoxic effects of the spike protein and to consider possible interventions to mitigate spike protein-related detrimental effects to the brain, possibly via use of small natural molecules, especially the flavonoids luteolin and quercetin.

Histopathological and Clinical Analysis of Skin Rashes in Children With Multisystem Inflammatory Syndrome Associated With COVID-19

INTRODUCTION

A new entity, which occurs a few weeks after SARS-CoV-2 infection and resembling incomplete Kawasaki disease or toxic shock syndrome, has been defined and named multisystem inflammatory syndrome (MIS-C) associated with COVID-19 in children. The aim of our study was to describe histopathological characteristics of skin lesions of MIS-C patients to reveal whether there is a relationship between histopathological features and clinical manifestations.

MATERIALS AND METHODS

Seventeen who had skin involvement of 57 patients who were diagnosed with MIS-C between December 2020 and February 2021 were included in this prospective study. Demographic information, laboratory findings, and patients' managements were recorded. Skin biopsies were taken simultaneously of each patient. Formalin-fixed, paraffin-embedded skin samples were examined microscopically.

RESULTS

The rate of skin rash was 30% in patients with MIS-C and was predominantly the maculopapular type. The anatomical distribution of the rash was evaluated as localized in 10 and generalized in 7 patients. In patients with myocarditis, C-reactive protein and fibrinogen were found to be significantly higher, and lymphocyte and albumin values were found to be low. Herpes-like inclusions were found in the microscopic examination of 2 patients with a history of zona zoster in themselves or in their mother. There was a significant difference between keratinocyte necrosis and some clinical parameters.

DISCUSSION

Localized skin lesions appear to be associated with a more severe inflammatory.

Arterial and Venous Thrombosis Complicated in COVID-19: A Retrospective Single Center Analysis in Japan

Background: Thrombosis is a characteristic complication in coronavirus disease 2019 (COVID-19). Since coagulopathy has been observed over the entire clinical course, thrombosis might be a clue to understanding the specific pathology in COVID-19. Currently, there is limited epidemiological data of COVID-19-associated thrombosis in the Japanese population and none regarding variant strains of SARS-CoV-2. Here, we elucidate the risk factors and the pattern of thrombosis in COVID-19 patients. Methods: The patients consecutively admitted to Tokyo Medical and Dental University Hospital with COVID-19 were retrospectively analyzed. SARS-CoV-2 variants of concern/interest (VOC/VOI) carrying the spike protein mutants E484K, N501Y, or L452R were identified by PCR-based analysis. All thrombotic events were diagnosed by clinical symptoms, ultrasonography, and/or radiological tests. Results: Among the 516 patients, 32 patients experienced 42 thromboembolic events. Advanced age, severe respiratory conditions, and several abnormal laboratory markers were associated with the development of thrombosis. While thrombotic events occurred in 13% of the patients with a severe respiratory condition, those events still occurred in 2.5% of the patients who did not require oxygen therapy. Elevated D-dimer and ferritin levels on admission were independent risk factors of thrombosis (adjusted odds ratio 9.39 and 3.11, 95% confidence interval 2.08-42.3, and 1.06-9.17, respectively). Of the thrombotic events, 22 were venous, whereas 20 were arterial. While patients with thrombosis received anticoagulation and antiinflammatory therapies with a higher proportion, the mortality rate, organ dysfunctions, and bleeding complications in these patients were higher than those without thrombosis. The incidence of thrombosis in COVID-19 became less frequent over time, such as during the replacement of the earlier strains of SARS-CoV-2 by VOC/VOI and during increased use of anticoagulatory therapeutics. Conclusion: This study elucidated that elevated D-dimer and ferritin levels are useful biomarkers of thrombosis in COVID-19 patients. The comparable incidence of arterial thrombosis with venous thrombosis and the development of thrombosis in less severe patients required further considerations for the management of Japanese patients with COVID-19. Further studies would be required to identify high-risk populations and establish appropriate interventions for thrombotic complications in COVID-19.

SARS-CoV-2: Current trends in emerging variants, pathogenesis, immune responses, potential therapeutic, and vaccine development strategies

More than a year after the SARS-CoV-2 pandemic, the Coronavirus disease 19 (COVID-19) is still a major global challenge for scientists to understand the different dimensions of infection and find ways to prevent, treat, and develop a vaccine. On January 30, 2020, the world health organization (WHO) officially announced this new virus as an international health emergency. While many biological and mechanisms of pathogenicity of this virus are still unclear, it seems that cytokine storm resulting from an immune response against the virus is considered the main culprit of the severity of the disease. Despite many global efforts to control the SARS-CoV-2, several problems and challenges have been posed in controlling the COVID-19 infection. These problems include the various mutations, the emergence of variants with high transmissibility, the short period of immunity against the virus, the possibility of reinfection in people improved, lack of specific drugs, and problems in the development of highly sensitive and specific vaccines. In this review, we summarized the results of the current trend and the latest research studies on the characteristics of the structure and genome of the SARS-CoV- 2, new mutations and variants of SARS-CoV-2, pathogenicity, immune response, virus diagnostic tests, potential treatment, and vaccine candidate.

Cutaneous coronavirus disease 2019 in children: a clinical primer for diagnosis and treatment

PURPOSE OF REVIEW

This review examines the global literature regarding rashes encountered in children and adults infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and aims to provide practicing pediatricians with an understanding of the relationship between instances of rashes and coronavirus disease 2019 (COVID-19) in children in order to effectively evaluate and treat patients.

RECENT FINDINGS

The true incidence of cutaneous reactions in children infected with SARS-CoV-2 is not known. Children's immune systems differ from those of adults and rashes as a manifestation of immune responses, in turn, differ in morphology and distribution. Rarely, children develop a severe multisystem inflammatory syndrome that has overlapping clinical features with Kawasaki disease. In addition, vaccinations produce rashes similar to natural infections. The rashes associated with COVID-19 vaccination are mild and transient, and should not preclude vaccination. Lastly, children who chronically wear masks are more likely to experience flaring of acne around the nose and mouth ('maskne') and facial conditions such as seborrheic dermatitis.

SUMMARY

There are ongoing worldwide registries, clinical and basic science studies to better understand the burden of skin disease and pathophysiology of rashes seen in patients infected with COVID-19. Robust vaccination programs should be encouraged as a way to contain viral spread among children and the greater population.

An Insight into the Role of Postmortem Immunohistochemistry in the Comprehension of the Inflammatory Pathophysiology of COVID-19 Disease and Vaccine-Related Thrombotic Adverse Events: A Narrative Review

On 11 March 2020, the World Health Organization (WHO) declared a pandemic due to the spread of COVID-19 from Wuhan, China, causing high mortality rates all over the world. The related disease, which mainly affects the lungs, is responsible for the onset of Diffuse Alveolar Damage (DAD) and a hypercoagulability state, frequently leading to Severe Acute Respiratory Syndrome (SARS) and multiorgan failure, particularly in old and severe-critically ill patients. In order to find effective therapeutic strategies, many efforts have been made aiming to shed light on the pathophysiology of COVID-19 disease. Moreover, following the late advent of vaccination campaigns, the need for the comprehension of the pathophysiology of the fatal, although rare, thrombotic adverse events has become mandatory as well. The achievement of such purposes needs a multidisciplinary approach, depending on a correct interpretation of clinical, biochemical, biomolecular, and forensic findings. In this scenario, autopsies have helped in defining, on both gross and histologic examinations, the main changes to which the affected organs undergo and the role in assessing whether a patient is dead “from” or “with” COVID-19, not to mention whether the existence of a causal link exists between vaccination and thrombotic adverse events. In the present work, we explored the role of postmortem immunohistochemistry, and the increasingly used ancillary technique, in helping to understand the mechanism underlying the pathophysiology of both COVID-19 disease and COVID-19 vaccine-related adverse and rare effects.

The skin as a critical window in unveiling the pathophysiologic principles of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent of coronavirus disease 2019 (COVID-19), is a single-stranded RNA virus whose sequence is known. COVID-19 is associated with a heterogeneous clinical phenotype ranging from asymptomatic to fatal disease. It appears that access to nasopharyngeal respiratory epithelia expressing angiotensin-converting enzyme (ACE) 2, the receptor for SARS-CoV-2, is followed by viral replication in the pulmonary alveolar septal capillary bed. We have demonstrated in earlier studies that incomplete viral particles, termed pseudovirions, dock to deep subcutaneous and other vascular beds, potentially contributing to the prothrombotic state and systemic complement activation that characterizes severe and critical COVID-19. A variety of skin eruptions have been described in the setting of SARS-CoV-2 infection and more recently, after COVID-19 vaccination. The vaccines deliver a laboratory-synthesized mRNA that encodes a protein that is identical to the spike glycoprotein of SARS-CoV-2, allowing the production of immunogenic spike glycoprotein that will then elicit T cell and B cell adaptive immune responses. In this contribution, we review an array of cutaneous manifestations of COVID-19 that provide an opportunity to study critical pathophysiologic mechanisms that underlie all clinical facets of COVID-19, ranging from asymptomatic/mild to severe and critical COVID-19. We classify cutaneous COVID-19 according to underlying pathophysiologic principles. In this regard we propose three main pathways: (1) complement mediated thrombotic vascular injury syndromes deploying the alternative and mannan binding lectin pathways and resulting in the elaboration of cytokines like interleukin 6 from endothelium in the setting of severe and critical COVID-19 and (2) the robust T cell and type I interferon-driven inflammatory and (3) humoral-driven immune complex mediated vasculitic cutaneous reactions observed with mild and moderate COVID-19. Presented are novel data on cutaneous vaccine reactions that manifest a clinical and morphologic parallel with similar eruptions observed in patients with mild and moderate COVID-19 and in some cases represent systemic eczematoid hypersensitivity reactions to a putative vaccine-based antigen versus unmasking subclinical hypersensitivity due to immune enhancing effects of the vaccine. Finally, we demonstrate for the first time the localization of human synthesized spike glycoprotein after the COVID-19 vaccine to the cutaneous and subcutaneous vasculature confirming the ability of SARS-CoV-2 spike glycoprotein to bind endothelium in the absence of intact virus.