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

Enhanced TLR7-dependent production of type I interferon by pDCs underlies pandemic chilblains

Outbreaks of chilblains were reported during the COVID-19 pandemic. Given the essential role of type I interferon (I-IFN) in protective immunity against SARS-CoV-2 and the association of chilblains with inherited type I interferonopathies, we hypothesized that excessive I-IFN responses to SARS-CoV-2 might underlie the occurrence of chilblains in this context. We identified a transient I-IFN signature in chilblain lesions, accompanied by an acral infiltration of activated plasmacytoid dendritic cells (pDCs). Patients with chilblains were otherwise asymptomatic or had mild disease without seroconversion. Their leukocytes produced abnormally high levels of I-IFN upon TLR7 stimulation with agonists or ssRNA viruses-particularly SARS-CoV-2-but not with DNA agonists of TLR9 or the dsDNA virus HSV-1. Moreover, the patients' pDCs displayed cell-intrinsic hyperresponsiveness to TLR7 stimulation regardless of TLR7 levels. Inherited TLR7 or I-IFN deficiency confers a predisposition to life-threatening COVID-19. Conversely, our findings suggest that enhanced TLR7 activity in predisposed individuals could confer innate, pDC-mediated, sterilizing immunity to SARS-CoV-2 infection, with I-IFN-driven chilblains as a trade-off.

Red Palms' Syndrome and Red Fingers' Syndrome: A Mini Review

Red palms syndrome consists of an intense redness on the palms of the hands and, occasionally, the soles of the feet. This infrequent condition may be primary or secondary. The primary forms are either familial or sporadic. They are always benign and do not require treatment. The secondary forms may have a poor prognosis related to the underlying disease, for which early identification and treatment are imperative. Red fingers syndrome is also rare. It manifests as a persistent redness on the fingers or toes pulp. It is typically secondary either to infectious diseases like human immunodeficiency virus, hepatitis C virus and chronic hepatitis B or to Myeloproliferative Disorders, such as Thrombocythemia and Polycythemia vera. Manifestations spontaneously regress over months or years without trophic alterations. Treatment is limited to that of the underlying condition. Aspirin has been shown effective in Myeloproliferative Disorders.

COVID-19 cooling: Nanostrategies targeting cytokine storm for controlling severe and critical symptoms

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continue to wreak havoc worldwide, the "Cytokine Storm" (CS, also known as the inflammatory storm) or Cytokine Release Syndrome has reemerged in the public consciousness. CS is a significant contributor to the deterioration of infected individuals. Therefore, CS control is of great significance for the treatment of critically ill patients and the reduction of mortality rates. With the occurrence of variants, concerns regarding the efficacy of vaccines and antiviral drugs with a broad spectrum have grown. We should make an effort to modernize treatment strategies to address the challenges posed by mutations. Thus, in addition to the requirement for additional clinical data to monitor the long-term effects of vaccines and broad-spectrum antiviral drugs, we can use CS as an entry point and therapeutic target to alleviate the severity of the disease in patients. To effectively combat the mutation, new technologies for neutralizing or controlling CS must be developed. In recent years, nanotechnology has been widely applied in the biomedical field, opening up a plethora of opportunities for CS. Here, we put forward the view of cytokine storm as a therapeutic target can be used to treat critically ill patients by expounding the relationship between coronavirus disease 2019 (COVID-19) and CS and the mechanisms associated with CS. We pay special attention to the representative strategies of nanomaterials in current neutral and CS research, as well as their potential chemical design and principles. We hope that the nanostrategies described in this review provide attractive treatment options for severe and critical COVID-19 caused by CS.

Damage to endothelial barriers and its contribution to long COVID

The world continues to contend with COVID-19, fueled by the emergence of viral variants. At the same time, a subset of convalescent individuals continues to experience persistent and prolonged sequelae, known as long COVID. Clinical, autopsy, animal and in vitro studies all reveal endothelial injury in acute COVID-19 and convalescent patients. Endothelial dysfunction is now recognized as a central factor in COVID-19 progression and long COVID development. Different organs contain different types of endothelia, each with specific features, forming different endothelial barriers and executing different physiological functions. Endothelial injury results in contraction of cell margins (increased permeability), shedding of glycocalyx, extension of phosphatidylserine-rich filopods, and barrier damage. During acute SARS-CoV-2 infection, damaged endothelial cells promote diffuse microthrombi and destroy the endothelial (including blood-air, blood-brain, glomerular filtration and intestinal-blood) barriers, leading to multiple organ dysfunction. During the convalescence period, a subset of patients is unable to fully recover due to persistent endothelial dysfunction, contributing to long COVID. There is still an important knowledge gap between endothelial barrier damage in different organs and COVID-19 sequelae. In this article, we mainly focus on these endothelial barriers and their contribution to long COVID.

Human Genomics of COVID-19 Pneumonia: Contributions of Rare and Common Variants

SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection is silent or benign in most infected individuals, but causes hypoxemic COVID-19 pneumonia in about 10% of cases. We review studies of the human genetics of life-threatening COVID-19 pneumonia, focusing on both rare and common variants. Large-scale genome-wide association studies have identified more than 20 common loci robustly associated with COVID-19 pneumonia with modest effect sizes, some implicating genes expressed in the lungs or leukocytes. The most robust association, on chromosome 3, concerns a haplotype inherited from Neanderthals. Sequencing studies focusing on rare variants with a strong effect have been particularly successful, identifying inborn errors of type I interferon (IFN) immunity in 1-5% of unvaccinated patients with critical pneumonia, and their autoimmune phenocopy, autoantibodies against type I IFN, in another 15-20% of cases. Our growing understanding of the impact of human genetic variation on immunity to SARS-CoV-2 is enabling health systems to improve protection for individuals and populations.

Interfering with Interferons: A Critical Mechanism for Critical COVID-19 Pneumonia

Infection with SARS-CoV-2 results in clinical outcomes ranging from silent or benign infection in most individuals to critical pneumonia and death in a few. Genetic studies in patients have established that critical cases can result from inborn errors of TLR3- or TLR7-dependent type I interferon immunity, or from preexisting autoantibodies neutralizing primarily IFN-α and/or IFN-ω. These findings are consistent with virological studies showing that multiple SARS-CoV-2 proteins interfere with pathways of induction of, or response to, type I interferons. They are also congruent with cellular studies and mouse models that found that type I interferons can limit SARS-CoV-2 replication in vitro and in vivo, while their absence or diminution unleashes viral growth. Collectively, these findings point to insufficient type I interferon during the first days of infection as a general mechanism underlying critical COVID-19 pneumonia, with implications for treatment and directions for future research.

Chilblain-Like Lesions (CLL) Coinciding With the SARS-CoV-2 Pandemic in Children: A Systematic Review

Chilblain-like lesions (CLL) coinciding with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection have been described in the literature. Available reviews of the literature suggest that CLL are associated with younger age, an equal sex ratio, negative testing for SARS-CoV-2, and mild to no extracutaneous manifestations (ECM) associated with COVID-19 infection. This systematic review aims to provide a summary of reports of CLL associated with the early SARS-CoV-2 pandemic in children to clarify the prevalence, clinical characteristics, and resolution outcomes of these skin findings. Sixty-nine studies, published between May 2020 and January 2022, met inclusion criteria and were summarized in this review, representing 1,119 cases of CLL. Available data showed a slight male predominance (591/1002, 59%). Mean age was 13 years, ranging from 0 to 18 years. Most cases had no ECM (682/978, 70%). Overall, 70/507 (14%) of patients tested positive for COVID-19 using PCR and/or serology. In the majority the clinical course was benign with 355/415 (86%) of cases resolving, and 97/269 (36%) resolving without any treatment. This comprehensive summary of pediatric CLL suggests these lesions are rarely associated with COVID-19 symptoms or test positivity.

Chilblain-like lesions onset during SARS-CoV-2 infection in a COVID-19-vaccinated adolescent: case report and review of literature

Background

COVID toes or chilblain-like skin lesions have been widely reported during COVID-19 pandemic. Most cases were described in patients with negative microbiological tests for SARS-CoV-2, therefore the possible relationship with SARS-CoV-2 infection, as well as with the nowadays broadly available mRNA-based vaccination, has not been fully elucidated. 

Case presentation

We here describe the case of a 14-year-old male who developed chilblain-like skin eruptions during SARS-CoV-2 infection despite two mRNA-based vaccine doses and review the clinical and epidemiological characteristics of chilblain-like lesions as a cutaneous presentation of COVID-19 in children.

Conclusions

Most children and adolescent with COVID toes have a mild or asymptomatic SARS-CoV-2 infection. Our report aims to highlight the possible onset of these skin lesions in vaccinated children, if infection has occurred, and the potential use of systemic corticosteroids as a first line treatment. Additional evidence is required to better understand SARS-CoV-2 infection and cutaneous manifestations in children and determine the relationship between chilblain-like lesions and COVID-19 vaccination.

COVID-19 2022 update: transition of the pandemic to the endemic phase

COVID-19, which is caused by the SARS-CoV-2, has ravaged the world for the past 2 years. Here, we review the current state of research into the disease with focus on its history, human genetics and genomics and the transition from the pandemic to the endemic phase. We are particularly concerned by the lack of solid information from the initial phases of the pandemic that highlighted the necessity for better preparation to face similar future threats. On the other hand, we are gratified by the progress into human genetic susceptibility investigations and we believe now is the time to explore the transition from the pandemic to the endemic phase. The latter will require worldwide vigilance and cooperation, especially in emerging countries. In the transition to the endemic phase, vaccination rates have lagged and developed countries should assist, as warranted, in bolstering vaccination rates worldwide. We also discuss the current status of vaccines and the outlook for COVID-19.

What Do We Need to Know About Musculoskeletal Manifestations of COVID-19?: A Systematic Review

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COVID-19 is a disease that is challenging science, health-care systems, and humanity. An astonishingly wide spectrum of manifestations of multi-organ damage, including musculoskeletal, can be associated with SARS-CoV-2.

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In the acute phase of COVID-19, fatigue, myalgia, and arthralgia are the most common musculoskeletal symptoms.

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Post-COVID-19 syndrome is a group of signs and symptoms that are present for >12 weeks. The associated musculoskeletal manifestations are fatigue, arthralgia, myalgia, new-onset back pain, muscle weakness, and poor physical performance.

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Data on COVID-19 complications are growing due to large absolute numbers of cases and survivors in these 2 years of the pandemic. Additional musculoskeletal manifestations encountered are falls by the elderly, increased mortality after hip fracture, reduced bone mineral density and osteoporosis, acute sarcopenia, rhabdomyolysis, Guillain-Barré syndrome, muscle denervation atrophy, fibromyalgia, rheumatological disease triggering, septic arthritis, adhesive capsulitis, myositis, critical illness myopathy, onset of latent muscular dystrophy, osteonecrosis, soft-tissue abscess, urticarial vasculitis with musculoskeletal manifestations, and necrotizing autoimmune myositis.

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A wide range of signs and symptoms involving the musculoskeletal system that affect quality of life and can result in a decrease in disability-adjusted life years. This powerful and unpredictable disease highlights the importance of multimodality imaging, continuing education, and multidisciplinary team care to support preventive measures, diagnosis, and treatment.

Post COVID-19 Condition in Children and Adolescents: An Emerging Problem

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection became a pandemic in 2020 and by March 2022 had caused more than 479 million infections and 6 million deaths worldwide. Several acute and long-term symptoms have been reported in infected adults, but it remains unclear whether children/adolescents also experience persistent sequelae. Hence, we conducted a review of symptoms and pathophysiology associated with post-coronavirus disease 2019 (post-COVID-19) condition in children and adolescents. We reviewed the scientific literature for reports on persistent COVID-19 symptoms after SARS-CoV-2 infection in both children/adolescents and adults from 1 January 2020 to 31 March 2022 (based on their originality and relevance to the broad scope of this review, 26 reports were included, 8 focused on adults and 18 on children/adolescents). Persistent sequelae of COVID-19 are less common in children/adolescents than in adults, possibly owing to a lower frequency of SARS-CoV-2 infection and to the lower impact of the infection itself in this age group. However, cumulative evidence has shown prolonged COVID-19 to be a clinical entity, with few pathophysiological associations at present. The most common post-COVID-19 symptoms in children/adolescents are fatigue, lack of concentration, and muscle pain. In addition, we found evidence of pathophysiology associated with fatigue and/or headache, persistent loss of smell and cough, and neurological and/or cardiovascular symptoms. This review highlights the importance of unraveling why SARS-CoV-2 infection may cause post-COVID-19 condition and how persistent symptoms might affect the physical, social, and psychological well-being of young people in the future.

[Skin manifestations of COVID-19 and after COVID-19 vaccination]

Coronavirus disease 2019 (COVID-19) is a systemic disease induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that frequently presents with skin manifestations. The five most common skin lesions are pseudo-chilblain and maculopapular, urticarial, vesicular, and livedo/necrotizing skin lesions. These skin lesions are of diagnostic and prognostic relevance. For example, in children, typical skin lesions may indicate a life-threatening inflammatory syndrome, which rarely occurs after corona infection. Skin lesions have also been described after COVID-19 vaccination. These usually show an uncomplicated, self-limiting course and therefore do not represent a contraindication for completing the vaccination status in the vast majority of cases.

Evolution of incidence of chilblain-like lesions in children during the first year of COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic has brought innumerable reports of chilblains. The relation between pernio-like acral eruptions and COVID-19 has not been fully elucidated because most reported cases have occurred in patients with negative microbiological tests for SARS-CoV-2.

METHODS

A retrospective study of 49 cases of chilblains seen during the first year of the pandemic in a children's hospital in Madrid, Spain. The incidence of these skin lesions was correlated with the number of COVID-19 admissions and environmental temperatures. Patients were separated into two groups depending on the day of onset (strict lockdown period vs. outside the lockdown period).

RESULTS

Most chilblains cases presented during the first and third waves of the pandemic, paralleling the number of COVID-19 admissions. The first wave coincided with a strict lockdown, and the third wave coincided with the lowest ambient seasonal temperatures of the year. Systemic symptoms preceding chilblains were more frequent in the first wave (45.8% vs. 8.0%, p = .002), as was the co-occurrence with erythema multiforme-like lesions (16.7% vs. 0%, p = .033). Laboratory test and skin biopsies were performed more frequently in the first wave (75.0% vs. 12.0%, p < .001; and 25.0% vs. 0%, p = .007; respectively). Five patients developed recurrent cutaneous symptoms.

CONCLUSIONS

An increased incidence of chilblains coincided not only with the two major waves of the pandemic, but also with the strict lockdown period in the first wave and low seasonal temperatures during the third wave. Both increased sedentary behaviors and cold environmental temperatures may have played an additive role in the development of COVID-19-related chilblains.

Human genetic and immunological determinants of critical COVID-19 pneumonia

SARS-CoV-2 infection is benign in most individuals but, in _˜10% of cases, it triggers hypoxemic COVID-19 pneumonia, which becomes critical in _˜3% of cases. The ensuing risk of death (_˜1%) doubles every five years from childhood onward and is _˜1.5 times greater in men than in women. What are the molecular and cellular determinants of critical COVID-19 pneumonia? Inborn errors of type I IFNs, including autosomal TLR3 and X-linked TLR7 deficiencies, are found in _˜1-5% of patients with critical pneumonia under 60 years old, and a lower proportion in older patients. Pre-existing autoantibodies neutralizing IFN-α, -β, and/or -ω, which are more common in men than in women, are found in _˜15-20% of patients with critical pneumonia over 70 years old, and a lower proportion in younger patients. Thus, at least 15% of cases of critical COVID-19 pneumonia can apparently be explained. The TLR3- and TLR7-dependent production of type I IFNs by respiratory epithelial cells and plasmacytoid dendritic cells, respectively, is essential for host defense against SARS-CoV-2. In ways that can depend on age and sex, insufficient type I IFN immunity in the respiratory tract during the first few days of infection may account for the spread of the virus, leading to pulmonary and systemic inflammation.

Type I Interferon and the Spectrum of Susceptibility to Viral Infection and Autoimmune Disease: A Shared Genomic Signature

Type I interferons (IFN-I) and their cognate receptor, the IFNAR1/2 heterodimer, are critical components of the innate immune system in humans. They have been widely explored in the context of viral infection and autoimmune disease where they play key roles in protection against infection or shaping disease pathogenesis. A false dichotomy has emerged in the study of IFN-I where interferons are thought of as either beneficial or pathogenic. This 'good or bad' viewpoint excludes more nuanced interpretations of IFN-I biology - for example, it is known that IFN-I is associated with the development of systemic lupus erythematosus, yet is also protective in the context of infectious diseases and contributes to resistance to viral infection. Studies have suggested that a shared transcriptomic signature underpins both potential resistance to viral infection and susceptibility to autoimmune disease. This seems to be particularly evident in females, who exhibit increased viral resistance and increased susceptibility to autoimmune disease. The molecular mechanisms behind such a signature and the role of sex in its determination have yet to be precisely defined. From a genomic perspective, several single nucleotide polymorphisms (SNPs) in the IFN-I pathway have been associated with both infectious and autoimmune disease. While overlap between infection and autoimmunity has been described in the incidence of these SNPs, it has been overlooked in work and discussion to date. Here, we discuss the possible contributions of IFN-Is to the pathogenesis of infectious and autoimmune diseases. We comment on genetic associations between common SNPs in IFN-I or their signalling molecules that point towards roles in protection against viral infection and susceptibility to autoimmunity and propose that a shared transcriptomic and genomic immunological signature may underlie resistance to viral infection and susceptibility to autoimmunity in humans. We believe that defining shared transcriptomic and genomic immunological signatures underlying resistance to viral infection and autoimmunity in humans will reveal new therapeutic targets and improved vaccine strategies, particularly in females.