Docked severe acute respiratory syndrome coronavirus 2 proteins within the cutaneous and subcutaneous microvasculature and their role in the pathogenesis of severe coronavirus disease 2019

Redefining Calciphylaxis as a Uniquely Bone Forming Subcutaneous C5b-9-Mediated Microvascular Injury Syndrome Associated With Localized Subcutaneous and Systemic Complement Pathway Activation

BACKGROUND

Microvascular thrombosis is key to the pathogenesis of calciphylaxis. C5b-9-mediated microvascular injury reflective of complement pathway activation could be a key pathophysiologic event.

METHODS

We conducted a retrospective multicenter study of 24 patients who have had biopsy-supported calciphylaxis from the 2010-2022 data base from Emory where C5b-9 immunohistochemistry (IHC) had not been conducted and the 2019-2023 data base from Cornell where C5b-9 IHC was done as part of the routine calciphylaxis work up. IHC for C5b-9 on lesional biopsy specimens was assessed and correlated with routine light microscopic findings and clinical features.

RESULTS

Most of the patients in our study had uremic calciphylaxis associated with obesity, diabetes, dialysis, hypertension, hyperparathyroidism and elevated serum phosphorus. Most patients did not have defined procoagulant and/or hyperviscosity states. The vascular pathology was predominantly limited to the subcutaneous fat and ranged from a calcific intimal arteriopathy to microvascular thrombosis with endothelial injury with or without endothelial calcification. In most cases (ie, in excess of 80%), there was prominent deposition of C5b-9 within the vasculature including the microvasculature and arteries of the fat at least localized to injured vessels suggesting a causal association. In about 40% of cases, there was evidence of systemic complement pathway activation revealed by concurrent dermal microvascular C5b-9 deposition.

CONCLUSIONS

Calciphylaxis is characterized by subcuticular vascular changes that reflect an interplay between complement triggered endothelial cell injury, resultant vascular thrombosis, and subsequent abluminal calcification. Complement inhibition therapy defines a potential intervention that should be explored.

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.

Tumor necrosis factor ALPHA Inhibitor Associated Köhlmeier-Degos Disease as a Novel Iatrogenic Paradigm That Underscores Excessive Type I Interferon in Its Pathogenesis

ABSTRACT

Malignant atrophic papulosis/Köhlmeier-Degos disease was first described in 1941 by Köhlmeier in an anecdotal case report that described a young man who presented with extensive multiple intestinal perforations and a papular skin rash. Köhlmeier-Degos disease represents a unique vasculopathy targeting both the microvasculature and the arterial system. One of its most characteristic features is reflected by the discrete multifocal depressed porcelain lesions involving the skin and gastrointestinal tract. The pathological findings are striking and can be broadly categorized into those that are vascular in nature versus extravascular matrix production in the context of extensive extravascular hyaluronic acid and collagen deposition. A dynamic evolutionary morphology is observed not only clinically but also histologically. The microvascular alterations are particularly evident in the skin and are characterized by endothelial cell necrosis with subsequent endothelial cell detachment accompanied by intraluminal fibrin deposition, defining a thrombogenic microangiopathy that in later stage lesions is typically pauci-inflammatory. The arterial lesions are very distinctive and include significant neointimal proliferation with vascular luminal occlusion by amorphous plugs of collagen intimately admixed with platelets. Pathogenetically enhanced type I interferon signaling and endothelial cell injury mediated by the membranolytic attack complex (ie, C5b-9) are key in the evolution of the thrombotic microvascular and obliterative fibrosing arteriopathic changes. We describe a case of Köhlmeier-Degos disease that developed in the setting of tumor necrosis factor (TNF)-alpha inhibitor therapy with the drug golimumab. The clinical features, light microscopic findings, and a pathophysiologic paradigm based on the critical role of TNF-alpha in controlling the type I interferon response are discussed.

Sialylated Glycan Bindings from SARS-CoV-2 Spike Protein to Blood and Endothelial Cells Govern the Severe Morbidities of COVID-19

Consistent with well-established biochemical properties of coronaviruses, sialylated glycan attachments between SARS-CoV-2 spike protein (SP) and host cells are key to the virus's pathology. SARS-CoV-2 SP attaches to and aggregates red blood cells (RBCs), as shown in many pre-clinical and clinical studies, causing pulmonary and extrapulmonary microthrombi and hypoxia in severe COVID-19 patients. SARS-CoV-2 SP attachments to the heavily sialylated surfaces of platelets (which, like RBCs, have no ACE2) and endothelial cells (having minimal ACE2) compound this vascular damage. Notably, experimentally induced RBC aggregation in vivo causes the same key morbidities as for severe COVID-19, including microvascular occlusion, blood clots, hypoxia and myocarditis. Key risk factors for COVID-19 morbidity, including older age, diabetes and obesity, are all characterized by markedly increased propensity to RBC clumping. For mammalian species, the degree of clinical susceptibility to COVID-19 correlates to RBC aggregability with p = 0.033. Notably, of the five human betacoronaviruses, the two common cold strains express an enzyme that releases glycan attachments, while the deadly SARS, SARS-CoV-2 and MERS do not, although viral loads for COVID-19 and the two common cold infections are similar. These biochemical insights also explain the previously puzzling clinical efficacy of certain generics against COVID-19 and may support the development of future therapeutic strategies for COVID-19 and long COVID patients.

Microvascular C5b-9 deposition in non-lesional skin in patients with SLE and its correlation with active lupus nephritis: a prospective observational study

OBJECTIVE

Tissue damage in lupus nephritis (LN) is mediated by activation of the classical complement pathway. Complement-mediated upregulation of endothelial cell adhesion molecules is seen in dermal blood vessels of non-lesional skin of patients with active lupus. In diseases with systemic complement activation, extensive microvascular C5b-9 deposition is seen in non-lesional skin. In this study, we assess the presence of systemic complement pathway activation as determined by non-lesional skin microvascular C5b-9 deposition in patients with LN.

METHODS

Eight patients with active LN and eight patients without active LN underwent non-lesional skin biopsies. Using a diaminobenzidine technique, specimens were evaluated for microvascular C5b-9 consistent with systemic complement pathway activation.

RESULTS

Five of eight patients with active LN and one of eight patients without active LN demonstrated positive C5b-9 staining in non-lesional skin (p=0.04). Positive non-lesional C5b-9 staining has greater specificity, 87.5%, for active LN than pyuria, low complements, elevated double-stranded DNA (dsDNA) and proteinuria. Urine protein creatinine ratio was significantly higher in patients with positive non-lesional C5b-9 deposition (5.18 vs 1.20; p=0.04). C5b-9 deposition was not associated with a higher NIH Activity Index, interstitial fibrosis, dsDNA or lower complements.

CONCLUSION

This is the first study to demonstrate evidence in non-lesional skin of microvascular C5b-9 indicative of systemic complement pathway activation in LN. C5b-9 deposition is statistically more common and demonstrated greater specificity than most historical biomarkers for active LN. The findings support a potential role for microvascular C5b-9 assessment in non-lesional skin as a biomarker for LN activity.

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.

Cutaneous manifestations in elderly patients with confirmed coronavirus disease 2019 and the disease outcomes: A systematic review

Cutaneous manifestations in coronavirus disease 2019 (COVID-19) patients may possess prognostic value for identifying potentially severe cases. This systematic review investigated whether dermatological features are associated with COVID-19 outcomes in elderly patients. Literature retrieval was conducted on May 11, 2022, from databases, hand-searching, and tracing citations. Following selection against eligibility criteria, the remaining records were evaluated utilizing the National Heart, Lung, and Blood Institute Study Quality Assessment Tool or Newcastle-Ottawa Scale. The pooled individual data were subsequently analyzed using the Cochran-Mantel-Haenszel test to calculate the odds ratio (ORs) and confidence intervals (CIs) for the severity and mortality of each skin lesion type. We incorporated 70 articles, including 180 and 117 entries, with information regarding disease severity and mortality. Further analysis revealed that vascular type was the skin lesion most frequently noticed in confirmed COVID-19 elderly patients (46.2%) and was associated with an increased risk of developing advanced disease (OR 7.32, 95% CI 3.39-15.81) and the ensuing termination (OR 5.73, 95% CI 2.46-13.36). The converse phenomenon was observed in maculopapular type (severity OR 0.27, 95% CI 0.14-0.52; mortality OR 0.10, 95% CI 0.03-0.36). In conclusion, skin manifestations may predict COVID-19 severity and mortality in the senior group.

Complement activation in COVID-19 and targeted therapeutic options: A scoping review

Increasing evidence suggests that activation of the complement system plays a key role in the pathogenesis and disease severity of Coronavirus disease 2019 (COVID-19). We used a systematic approach to create an overview of complement activation in COVID-19 based on histopathological, preclinical, multiomics, observational and clinical interventional studies. A total of 1801 articles from PubMed, EMBASE and Cochrane was screened of which 157 articles were included in this scoping review. Histopathological, preclinical, multiomics and observational studies showed apparent complement activation through all three complement pathways and a correlation with disease severity and mortality. The complement system was targeted at different levels in COVID-19, of which C5 and C5a inhibition seem most promising. Adequately powered, double blind RCTs are necessary in order to further investigate the effect of targeting the complement system in COVID-19.

[Translated article] COVID-19 and Dermal Fillers: Should We Really Be Concerned?

SARS-CoV-2 has caused millions of infections and deaths worldwide and case numbers continue to rise. Besides the effect of the virus on key organs - leading to respiratory illness, anosmia, diarrhea, and fever and other complications - delayed inflammatory reactions to hyaluronic acid dermal fillers, mainly in the face, have also been reported to occur after confirmed SARS-CoV-2 infections and in vaccinated individuals. While delayed inflammatory reactions tend to be self-limiting, they should be diagnosed and treated with corticosteroids, hyaluronidase, and/or antibiotics when necessary. The inflammation is generally not severe, yet these complications are classified as serious adverse events by the US Food and Drug Administration. They appear to be delayed type IV hypersensitivity reactions triggered by the immune system in the presence of SARS-CoV-2 or other viruses, such as those causing influenza, although the underlying mechanisms have not been fully elucidated. Because the longevity of dermal fillers is increasing, while the pandemic continues to evolve and new vaccines are under development, the long-term effects on hyaluronic acid fillers and other bioimplant materials should be studied. Physicians must also be encouraged to report these reactions, however mild, to ensure accurate records.

COVID-19, obesity, and immune response 2 years after the pandemic: A timeline of scientific advances

In the 2 years since the COVID-19 pandemic was officially declared, science has made considerable strides in understanding the disease's pathophysiology, pharmacological treatments, immune response, and vaccination, but there is still much room for further advances, especially in comprehending its relationship with obesity. Science has not yet described the mechanisms that explain how obesity is directly associated with a poor prognosis. This paper gathers all published studies over the past 2 years that have described immune response, obesity, and COVID-19, a historical and chronological record for researchers and the general public alike. In summary, these studies describe how the cytokine/adipokine levels and inflammatory markers, such as the C-reactive protein, are associated with a higher body mass index in COVID-19-positive patients, suggesting that the inflammatory background and immune dysregulation in individuals with obesity may be expressed in the results and that adiposity may influence the immune response. The timeline presented here is a compilation of the results of 2 years of scientific inquiry, describing how the science has progressed, the principal findings, and the challenges ahead regarding SARS-CoV-2, COVID-19, and emerging variants, especially in patients with obesity.

Morphoea following COVID-19 vaccination

We present a case of generalized morphoea developing after recent COVID-19 mRNA vaccination and suggest the plausible pathomechanisms.

COVID y rellenos faciales ¿realmente debemos preocuparnos?

La pandemia por COVID ha causado hoy en día millones de afectados, continuando su aumento a nivel mundial. Junto con la afectación los órganos diana clave (aparato respiratorio, anosmia, diarrea, fiebre, etc.), se han descrito reacciones inmunológicas tardías en los rellenos dérmicos por ácido hialurónico (AH), fundamentalmente a nivel facial. Estas alteraciones aparecen tanto en pacientes positivos para el virus, independientemente de la sintomatología sistémica, como en pacientes que han recibido vacunación frente al SARS-CoV-2. Aunque las reacciones suelen ser autolimitadas y autoresolutivas, es importante saber diagnosticarlas y en ocasiones establecer tratamiento con corticoides, hialuronidasa y/o antibióticos. Aunque no son graves, la Administración de Alimentos y Medicamentos de los Estados Unidos (FDA) las ha clasificado como evento adverso serio. Los mecanismos que originan están reacciones no están completamente dilucidados. Parece que son reacciones de hipersensibilidad retardada tipo IV, favorecidas por estímulos inmunológicos que se activan en presencia de la COVID o de otros virus como la gripe. Sin embargo, dado que los rellenos presentan cada vez mayor durabilidad y a que la pandemia continúa su curso, existiendo nuevas vacunas en desarrollo, es esencial la realización de estudios que describan la evolución a largo plazo tanto de los rellenos de AH, como de otros bioimplantes. Así mismo, es esencial alentar a los médicos de que reporten este tipo de reacciones, aunque no revistan gravedad con el objetivo de poder realizar un registro fidedigno de ellas.

Ex Vivo Test for Measuring Complement Attack on Endothelial Cells: From Research to Bedside

As part of the innate immune system, the complement system plays a key role in defense against pathogens and in host cell homeostasis. This enzymatic cascade is rapidly triggered in the presence of activating surfaces. Physiologically, it is tightly regulated on host cells to avoid uncontrolled activation and self-damage. In cases of abnormal complement dysregulation/overactivation, the endothelium is one of the primary targets. Complement has gained momentum as a research interest in the last decade because its dysregulation has been implicated in the pathophysiology of many human diseases. Thus, it appears to be a promising candidate for therapeutic intervention. However, detecting abnormal complement activation is challenging. In many pathological conditions, complement activation occurs locally in tissues. Standard routine exploration of the plasma concentration of the complement components shows values in the normal range. The available tests to demonstrate such dysregulation with diagnostic, prognostic, and therapeutic implications are limited. There is a real need to develop tools to demonstrate the implications of complement in diseases and to explore the complex interplay between complement activation and regulation on human cells. The analysis of complement deposits on cultured endothelial cells incubated with pathologic human serum holds promise as a reference assay. This ex vivo assay most closely resembles the physiological context. It has been used to explore complement activation from sera of patients with atypical hemolytic uremic syndrome, malignant hypertension, elevated liver enzymes low platelet syndrome, sickle cell disease, pre-eclampsia, and others. In some cases, it is used to adjust the therapeutic regimen with a complement-blocking drug. Nevertheless, an international standard is lacking, and the mechanism by which complement is activated in this assay is not fully understood. Moreover, primary cell culture remains difficult to perform, which probably explains why no standardized or commercialized assay has been proposed. Here, we review the diseases for which endothelial assays have been applied. We also compare this test with others currently available to explore complement overactivation. Finally, we discuss the unanswered questions and challenges to overcome for validating the assays as a tool in routine clinical practice.

Erythema nodosum after COVID-19 vaccine

The current coronavirus disease 2019 (COVID-19) pandemic is a global challenge with strong medical and socioeconomic implications. Hopes have been placed in the development of various vaccines. As the vaccination campaign is in progress, adverse effects need to be monitored closely. Possible side effects range from minor events to more serious manifestations. In this article, we describe two cases of erythema nodosum (EN) after COVID-19 vaccination in two previously healthy female patients of 59 and 51 years, respectively. Most of the usual etiologies of EN were excluded by laboratory testing. EN was successfully treated with corticosteroids. Remarkably, in the first case, a relapse occurred 48 hours after the second dose of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. In this case series, we describe two unusual occurrences of EN after vaccination with an mRNA COVID-19 vaccine and a viral vector vaccine, respectively, and we discuss the available related literature.

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.

A Deadly Embrace: Hemagglutination Mediated by SARS-CoV-2 Spike Protein at Its 22 N-Glycosylation Sites, Red Blood Cell Surface Sialoglycoproteins, and Antibody

Rouleaux (stacked clumps) of red blood cells (RBCs) observed in the blood of COVID-19 patients in three studies call attention to the properties of several enveloped virus strains dating back to seminal findings of the 1940s. For COVID-19, key such properties are: (1) SARS-CoV-2 binds to RBCs in vitro and also in the blood of COVID-19 patients; (2) although ACE2 is its target for viral fusion and replication, SARS-CoV-2 initially attaches to sialic acid (SA) terminal moieties on host cell membranes via glycans on its spike protein; (3) certain enveloped viruses express hemagglutinin esterase (HE), an enzyme that releases these glycan-mediated bindings to host cells, which is expressed among betacoronaviruses in the common cold strains but not the virulent strains, SARS-CoV, SARS-CoV-2 and MERS. The arrangement and chemical composition of the glycans at the 22 N-glycosylation sites of SARS-CoV-2 spike protein and those at the sialoglycoprotein coating of RBCs allow exploration of specifics as to how virally induced RBC clumping may form. The in vitro and clinical testing of these possibilities can be sharpened by the incorporation of an existing anti-COVID-19 therapeutic that has been found in silico to competitively bind to multiple glycans on SARS-CoV-2 spike protein.

A Standardization Protocol for the In Situ Detection of SARS-CoV2 RNA and Proteins

This manuscript details a stringent protocol for the in situ detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) RNA and 4 different viral proteins: envelope, spike, membrane, and nucleocapsid. Key aspects of the protocol are: (1) analysis of adjacent (serial) sections for viral RNA and at least 2 viral proteins; (2) cytologic alterations in the cells scored as virus positive based on an hematoxylin and eosin stain; (3) in situ demonstration of a host response in the cells scored as virus positive; (4) co-labeling experiments that show that the viral RNA and/or proteins co-localize with each other and the angiotensin converting enzyme 2 (ACE2) receptor; and (5) lack of signal in equivalent tissues obtained before the pandemic. Optimization conditions for the four viral proteins as well as the ACE2 receptor were each antigen retrieval in an EDTA solution which facilitates co-expression analyses. It is recommended not to use either electron microscopy or qRTPCR as methods to corroborate in situ SARS-CoV2 detection. This stringent protocol, that relies on sequentially labeled serial sections and can be completed in one working day, demonstrated the following: (1) infectious SARS-CoV2 is abundant in the lung in fatal coronavirus disease-2019 and is seen primarily in macrophages and endothelial cells; (2) circulating viral capsid proteins (spike, envelope, membrane without RNA) are evident in multiple organs including the skin and brain where it is endocytosed by ACE2+ cells and induce an endothelialitis; (3) both the infectious virus and circulating spike protein induce complement activation and cytologic changes in the viral positive cells.

"COVID-19/SARS-CoV-2 virus spike protein-related delayed inflammatory reaction to hyaluronic acid dermal fillers: a challenging clinical conundrum in diagnosis and treatment"

We present the first reported cases of delayed inflammatory reactions (DIR) to hyaluronic acid (HA) dermal fillers after exposure to the COVID-19 spike protein. DIR to HA is reported to occur in the different scenarios including: secondary to poor injection technique, following dental cleaning procedures, following bacterial/viral illness, and after vaccination. In this report of 4 cases with distinct clinical histories and presentations: one case occured following a community acquired COVID-19 infection, one case occured in a study subject in the mRNA-1273 clinical phase III trial, one case occurred following the first dose of publically available mRNA-1273 vaccine (Moderna, Cambridge MA), and the last case occurred after the second dose of BNT162b2 vaccine (Pfizer, New York, NY). Injectable HA dermal fillers are prevalent in aesthetic medicine for facial rejuvenation. Structural modifications in the crosslinking of HA fillers have enhanced the products' resistance to enzymatic breakdown and thus increased injected product longevity, however, have also led to a rise in DIR. Previous, DIR to HA dermal fillers can present clinically as edema with symptomatic and inflammatory erythematous papules and nodules. The mechanism of action for the delayed reaction to HA fillers is unknown and is likely to be multifactorial in nature. A potential mechanism of DIR to HA fillers in COVID-19 related cases is binding and blockade of angiotensin 2 converting enzyme receptors (ACE2), which are targeted by the SARS-CoV-2 virus spike protein to gain entry into the cell. Spike protein interaction with dermal ACE2 receptors favors a pro-inflammatory, loco-regional TH1 cascade, promoting a CD8+T cell mediated reaction to incipient granulomas, which previously formed around residual HA particles. Management to suppress the inflammatory response in the native COVID-19 case required high-dose corticosteroids (CS) to suppress inflammatory pathways, with concurrent ACE2 upregulation, along with high-dose intralesional hyaluronidase to dissolve the inciting HA filler. With regards to the two vaccine related cases; in the mRNA-1273 case, a low dose angiotensin converting enzyme inhibitor (ACE-I) was utilized for treatment, to reduce pro-inflammatory Angiotensin II. Whereas, in the BNT162b2 case the filler reaction was suppressed with oral corticosteroids. Regarding final disposition of the cases; the vaccine-related cases returned to baseline appearance within 3 days, whereas the native COVID-19 case continued to have migratory, evanescent, periorbital edema for weeks which ultimately subsided.

The histologic and molecular correlates of liver disease in fatal COVID-19 including with alcohol use disorder

Hepatic disease is common in severe COVID-19. This study compared the histologic/molecular findings in the liver in fatal COVID-19 (n = 9) and age-matched normal controls (n = 9); three of the fatal COVID-19 livers had pre-existing alcohol use disorder (AUD). Controls showed a high resident population of sinusoidal macrophages that had variable ACE2 expression. Histologic findings in the cases included periportal/lobular inflammation. SARS-CoV2 RNA and nucleocapsid protein were detected in situ in 2/9 COVID-19 livers in low amounts. In 9/9 cases, there was ample in situ SARS-CoV-2 spike protein that co-localized with viral matrix and envelope proteins. The number of cells positive for spike/100× field was significantly greater in the AUD/COVID-19 cases (mean 5.9) versus the non-AUD/COVID-19 cases (mean 0.4, p < 0.001) which was corroborated by Western blots. ACE2+ cells were 10× greater in AUD/COVID-19 livers versus the other COVID-19/control liver samples (p < 0.001). Co-expression experiments showed that the spike protein localized to the ACE2 positive macrophages and, in the AUD cases, hepatic stellate cells that were activated as evidenced by IL6 and TNFα expression. Injection of the S1, but not S2, subunit of spike in mice induced hepatic lobular inflammation in activated macrophages. It is concluded that endocytosed viral spike protein can induce hepatitis in fatal COVID-19. This spike induced hepatitis is more robust in the livers with pre-existing AUD which may relate to why patients with alcohol abuse are at higher risk of severe liver disease with SARS-CoV2 infection.

From Your Nose to Your Toes: A Review of Severe Acute Respiratory Syndrome Coronavirus 2 Pandemic‒Associated Pernio

Despite thousands of reported patients with pandemic-associated pernio, low rates of seroconversion and PCR positivity have defied causative linkage to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pernio in uninfected children is associated with monogenic disorders of excessive IFN-1 immunity, whereas severe COVID-19 pneumonia can result from insufficient IFN-1. Moreover, SARS-CoV-2 spike protein and robust IFN-1 response are seen in the skin of patients with pandemic-associated pernio, suggesting an excessive innate immune skin response to SARS-CoV-2. Understanding the pathophysiology of this phenomenon may elucidate the host mechanisms that drive a resilient immune response to SARS-CoV-2 and could produce relevant therapeutic targets.

The histologic and molecular correlates of COVID-19 vaccine-induced changes in the skin

A total of 22 patients who had developed an adverse cutaneous reaction to the Moderna or Pfizer vaccine underwent biopsies. Each patient was assessed light microscopically, and, in select biopsies, spike glycoprotein and cytokine assessment were also conducted. The patients developed self-limited cutaneous reactions often described clinically as urticarial or eczematous within 1 day to 4 weeks after receiving the first or second dose of the Pfizer or Moderna vaccine. Classic clinical and morphologic depictions of type IV cutaneous hypersensitivity with features of eczematous dermatitis, interface dermatitis, granulomatous inflammation, and/or lymphocytic vasculitic component were observed. Clinical and/or histologic features of perniosis, pityriasis rosea, pityriasis rubra pilaris, and guttate psoriasis were seen in select cases. In 2 cases the dominant picture was urticarial vasculitis, possibly reflective of an Arthus type III immune complex action. The biopsy specimens of normal skin post vaccine and of skin affected by the post-vaccine eruption showed rare deep microvessels positive for spike glycoprotein with no complement deposition contrasting with greater vascular deposition of spike protein and complement in skin biopsies from patients experiencing severe coronavirus disease 2019 (COVID-19). It is concluded that self-limited hypersensitivity reactions to the vaccine occur possibly owing to a substance found in the vaccine vehicle (eg, polyethylene glycol). An immune response that is directed against human-manufactured spike has to be considered because some of the reactions clinically and or histologically closely resemble mild COVID-19. Finally, vaccine-associated immune enhancement largely attributable to the adjuvant properties of the vaccine may unmask certain inflammatory milieus operational in psoriasis, atopic dermatitis, and subclinical hypersensitivity.

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.

Microvascular Skin Manifestations Caused by COVID-19

Hypercoagulability and vascular injury, which characterize morbidity in COVID-19 disease, are frequently observed in the skin. Several pathomechanisms, such as inflammation caused by angiotensin-converting enzyme 2-mediated uptake into endothelial cells or SARS-CoV-2-initiated host immune responses, contribute to microthrombus formation and the appearance of vascular skin lesions. Besides pathophysiologic mechanisms observed in the skin, this review describes the clinical appearance of cutaneous vascular lesions and their association with COVID-19 disease, including acro-ischemia, reticular lesions, and cutaneous small vessel vasculitis. Clinicians need to be aware that skin manifestations may be the only symptom in SARS-CoV-2 infection, and that inflammatory and thrombotic SARS-CoV-2-driven processes observed in multiple organs and tissues appear identically in the skin as well.

New-onset IgG autoantibodies in hospitalized patients with COVID-19

COVID-19 is associated with a wide range of clinical manifestations, including autoimmune features and autoantibody production. Here we develop three protein arrays to measure IgG autoantibodies associated with connective tissue diseases, anti-cytokine antibodies, and anti-viral antibody responses in serum from 147 hospitalized COVID-19 patients. Autoantibodies are identified in approximately 50% of patients but in less than 15% of healthy controls. When present, autoantibodies largely target autoantigens associated with rare disorders such as myositis, systemic sclerosis and overlap syndromes. A subset of autoantibodies targeting traditional autoantigens or cytokines develop de novo following SARS-CoV-2 infection. Autoantibodies track with longitudinal development of IgG antibodies recognizing SARS-CoV-2 structural proteins and a subset of non-structural proteins, but not proteins from influenza, seasonal coronaviruses or other pathogenic viruses. We conclude that SARS-CoV-2 causes development of new-onset IgG autoantibodies in a significant proportion of hospitalized COVID-19 patients and are positively correlated with immune responses to SARS-CoV-2 proteins.

Endothelial Immunity Trained by Coronavirus Infections, DAMP Stimulations and Regulated by Anti-Oxidant NRF2 May Contribute to Inflammations, Myelopoiesis, COVID-19 Cytokine Storms and Thromboembolism

To characterize transcriptomic changes in endothelial cells (ECs) infected by coronaviruses, and stimulated by DAMPs, the expressions of 1311 innate immune regulatomic genes (IGs) were examined in 28 EC microarray datasets with 7 monocyte datasets as controls. We made the following findings: The majority of IGs are upregulated in the first 12 hours post-infection (PI), and maintained until 48 hours PI in human microvascular EC infected by middle east respiratory syndrome-coronavirus (MERS-CoV) (an EC model for COVID-19). The expressions of IGs are modulated in 21 human EC transcriptomic datasets by various PAMPs/DAMPs, including LPS, LPC, shear stress, hyperlipidemia and oxLDL. Upregulation of many IGs such as nucleic acid sensors are shared between ECs infected by MERS-CoV and those stimulated by PAMPs and DAMPs. Human heart EC and mouse aortic EC express all four types of coronavirus receptors such as ANPEP, CEACAM1, ACE2, DPP4 and virus entry facilitator TMPRSS2 (heart EC); most of coronavirus replication-transcription protein complexes are expressed in HMEC, which contribute to viremia, thromboembolism, and cardiovascular comorbidities of COVID-19. ECs have novel trained immunity (TI), in which subsequent inflammation is enhanced. Upregulated proinflammatory cytokines such as TNFα, IL6, CSF1 and CSF3 and TI marker IL-32 as well as TI metabolic enzymes and epigenetic enzymes indicate TI function in HMEC infected by MERS-CoV, which may drive cytokine storms. Upregulated CSF1 and CSF3 demonstrate a novel function of ECs in promoting myelopoiesis. Mechanistically, the ER stress and ROS, together with decreased mitochondrial OXPHOS complexes, facilitate a proinflammatory response and TI. Additionally, an increase of the regulators of mitotic catastrophe cell death, apoptosis, ferroptosis, inflammasomes-driven pyroptosis in ECs infected with MERS-CoV and the upregulation of pro-thrombogenic factors increase thromboembolism potential. Finally, NRF2-suppressed ROS regulate innate immune responses, TI, thrombosis, EC inflammation and death. These transcriptomic results provide novel insights on the roles of ECs in coronavirus infections such as COVID-19, cardiovascular diseases (CVD), inflammation, transplantation, autoimmune disease and cancers.

A scoping review of the pathophysiology of COVID-19

COVID-19 is a highly heterogeneous and complex medical disorder; indeed, severe COVID-19 is probably amongst the most complex of medical conditions known to medical science. While enormous strides have been made in understanding the molecular pathways involved in patients infected with coronaviruses an overarching and comprehensive understanding of the pathogenesis of COVID-19 is lacking. Such an understanding is essential in the formulation of effective prophylactic and treatment strategies. Based on clinical, proteomic, and genomic studies as well as autopsy data severe COVID-19 disease can be considered to be the connection of three basic pathologic processes, namely a pulmonary macrophage activation syndrome with uncontrolled inflammation, a complement-mediated endothelialitis together with a procoagulant state with a thrombotic microangiopathy. In addition, platelet activation with the release of serotonin and the activation and degranulation of mast cells contributes to the hyper-inflammatory state. Auto-antibodies have been demonstrated in a large number of hospitalized patients which adds to the end-organ damage and pro-thrombotic state. This paper provides a clinical overview of the major pathogenetic mechanism leading to severe COVID-19 disease.

Complement Factors in COVID-19 Therapeutics and Vaccines

Complement is integral to a healthy functioning immune system and orchestrates various innate and adaptive responses against viruses and other pathogens. Despite its importance, the potential beneficial role of complement in immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been overshadowed by reports of extensive complement activation in severe coronavirus disease 2019 (COVID-19) patients. Here, we hypothesize that complement may also have a protective role and could function to enhance virus neutralization by antibodies, promote virus phagocytosis by immune cells, and lysis of virus. These functions might be exploited in the development of effective therapeutics and vaccines against SARS-CoV-2.

Complement has been implicated in playing some role in severe COVID-19 pathogenesis. However, the evidence to support this is largely inferred from case–control studies.

The potential protective role of complement has been largely ignored, which might contribute to innate and adaptive immunity against SARS-CoV-2 infection.

Immunity to many pathogens relies on complement to enhance antibody-mediated neutralization and mediate phagocytosis and lysis. These mechanisms might also contribute to immunity against SARS-CoV-2 infection, and complement might be potentially exploited in antibody-based therapeutics and vaccines.

Careful selection of vaccine adjuvants and epitopes included in vaccine constructs can influence whether vaccine-induced antibodies activate complement.

Mutations in monoclonal antibodies can be used to promote hexamer formation between antibodies, which can significantly improve complement binding and activation.