Multidisciplinary management of a quickly growing pediatric atypical Spitz nevus, mimicking melanoma, during the COVID-19 pandemic

Spitzoid melanoma is very rare tumour in the pediatric population, with clinical and non-uniform behaviour, different from adult melanoma [1]. It can be difficult to differentiate an atypical Spitz nevus from a Spitzoid melanoma, resulting in diagnostic problems. In addition, in our clinical case, the COVID-19pandemiccaused significant delays both in the diagnosis and in the surgical treatment of our patient. We present the clinical case of a 4-year-old child suffering from a localized polypoid cutaneous neoformation on the dorsum of the left hand, which started immediately before the lockdown and steadily increased during the COVID-19 pandemic. After a general clinical framing, the child underwent an excisional biopsy at our Department of Plastic and Reconstructive Surgery, at the Policlinico of Foggia. Subsequently, two independent anatomic pathology groups examined the specimen. Definitive diagnosis was made only after careful genetic analysis in combination with supporting histological and immunohistochemical examinations. This clinical case shows how during the pandemic we have been facing advanced forms of tumours, compared to the previous period and highlight show an interdisciplinary and multicenter collaboration allowed a quick diagnosis of certainty, demonstrating the utility of molecular pathology as a fundamental aid in clinical/surgical practice. © 2022 The Authors

Immunohistochemical profile of cell cycle control, proliferation and differentiation proteins of the pulmonary atypical alveolar epithelium with COVID-19-induced diffuse alveolar damage as compared to pulmonary [lepidic-growth] adenocarcinoma

We aim aim to compare immunophenotypic charac-teritics of atypical epithelium (AE) with COVID-19-induced diffuse alveolar damage (DAD) and pulmonary lepidic-growth adenocarcinoma, accounting for cell cycle control, proliferation and differentiation]. Methods. We examined pulmonary tissue specimens from twenty-four fatal cases of CO VID-19-induced acute respiratory damage syndrome confirmed by autopsy (Group 1) and four cases of pulmonary lepidic-growth adenocarcinoma (Group 2). Perpendicular dimensions of 10 nuclei were measured on the H&E slides, means of their sums of products (SPNM) were calculated. We have used p53, Ki67, pi6, p63 antibodies for immunohistochemical staining in each case. We evaluate co¬lour intensity, rate of stained cells of AE and the product of these parameters. We evaluated separately Nuclear and cyto-plasmic staining (couple) and only cytoplasmic staining (cyt) for pi6 expression. We measured proliferative index only at KI-67 stained slides. U-test and Spearman rank correlation test were used for statistical analysis. Results. Expression of p63 was higher in group 1 (p=0.001), while pi6 was more frequently expressed in group 2 (p=0.002). We have found no statistically significant differences (p>0.1) in the p53 and Ki67 expression. Group 1 showed There was negative correlation between the number of days from onset of symptoms and the following variables: Ki67 (r=M).587, p=0.003);SPNM (r 0.406, p=0.049). Conclusion. The present study has shown heterogeneity in levels of cell cycle control expression, proliferation and differentiation of atypical epithelium in the pulmonary lep-idic-growth adenocarcinoma and CO VID-19-induced diffuse alveolar damage.

Oral lesions with immunohistochemical evidence of Sars-CoV-2 in swab-negative post-COVID syndrome.

OBJECTIVES: Growing evidence exists about post-COVID condition/syndrome as sequelae of Sars-CoV-2 infection in healed patients, possibly involving the lungs, brain, kidney, cardiovascular and neuromuscular system, as well the persistency of taste dysfunction. Such symptoms develop during or after infection and continue for more than 12 weeks with pathogenesis related to virus persistency but variable by organs or systems. MATERIALS AND METHODS: We recently observed six patients recovered from COVID-19 and with negative RT-PCR testing, showing oral mucosa lesions (mainly ulcers) overlapping those occurring in the acute phase, persisting up to 20 days and thus needing a biopsy with histological investigation and spike protein evaluation by immunohistochemistry. RESULTS: We found epithelial ulceration, inflammatory infiltrate, vessels with increased diameter and flattened endothelium but no thrombi formation; also, we found a weak epithelial SARS-CoV-2 positivity limited to the basal/spinosum layers, progressively decreasing toward the periphery, and the intraepithelial lymphomonocytes, endothelium, and perivascular pericytes too. CONCLUSIONS: Our findings provide evidence that SARS-CoV-2 can persist, as for other organs/systems, also in the oral epithelium/mucosa after the acute phase and can be responsible for lesions, although by a pathogenetic mechanism that should be better defined but certainly referable as the oral mucosa counterpart of post-COVID syndrome.

Probable vertical transmission of Alpha variant of concern (B.1.1.7) with evidence of SARS-CoV-2 infection in the syncytiotrophoblast, a case report.

Introduction: Definitive vertical transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has been rarely reported. We present a case of a third trimester pregnancy with fetal distress necessitating cesarean section that demonstrated maternal, placental, and infant infection with the SARS-CoV-2 Alpha variant/B.1.1.7. Methods: CDC's Influenza SARS-CoV-2 Multiplex RT-PCR Assay was used to test for SARS-CoV-2 in a maternal NP swab, maternal plasma, infant NP swab, and formalin-fixed paraffin-embedded (FFPE) placental tissue specimens. Whole genome sequencing (WGS) was performed on maternal plasma, infant, and placental specimens to determine the SARS-CoV-2 genotype. Histopathological evaluation, SARS-CoV-2 immunohistochemistry testing (IHC), and electron microscopy (EM) analysis were performed on placenta, umbilical cord, and membrane FFPE blocks. Results: All specimens tested positive for SARS-CoV-2 by RT-PCR. WGS further revealed identical SARS-CoV-2 sequences from clade 20I/501Y.V1 (lineage Alpha/B.1.1.7) in maternal plasma, infant, and placental specimens. Histopathologic evaluation of the placenta showed histiocytic and neutrophilic intervillositis with fibrin deposition and trophoblast necrosis with positive SARS-CoV-2 immunostaining in the syncytiotrophoblast and electron microscopy evidence of coronavirus. Discussion: These findings suggest vertical transmission of SARS-CoV-2, supported by clinical course timing, identical SARS-CoV-2 genotypes from maternal, placental, and infant samples, and IHC and EM evidence of placental infection. However, determination of the timing or distinction between prepartum and peripartum SARS-CoV-2 transmission remains unclear.

Immunohistochemical detection of double-stranded RNA in formalin-fixed paraffin-embedded tissue.

Double-stranded RNA (dsRNA) is produced during most viral infections, and immunohistochemical detection of dsRNA has been proposed as a potential screening marker for viral replication. The anti-dsRNA monoclonal antibody clone 9D5 is more sensitive than the established clone J2 but has not been validated in formalin-fixed paraffin-embedded (FFPE) tissue. This study aimed to test and compare the performance of the anti-dsRNA monoclonal antibodies, 9D5 and J2, in FFPE tissue using an automated staining platform. Archived clinical tissue samples with viral infections (n = 34) and uninfected controls (n = 30) were examined. Immunohistochemical staining for dsRNA (9D5 and J2) and virus-specific epitopes was performed. 9D5 provided a similar staining pattern but a higher signal-to-noise ratio than J2. The following proportions of virus-infected tissue samples were dsRNA-positive: SARS-CoV-2 (5/5), HPV (6/6), MCV (5/5), CMV (5/6), HSV (4/6), and EBV (0/6). Also, 18 of 30 uninfected samples were dsRNA positive, and an association between fixation time and intensity was observed. However, signals in all samples were markedly reduced by pretreatment with dsRNA-specific RNAse-III, indicating a specific reaction. In conclusion, dsRNA can be demonstrated in most viral infections with immunohistochemistry in FFPE tissue but with low clinical specificity. The antibody clone 9D5 performs better than clone J2.

Monoclonal Antibodies Specific for SARS-CoV-2 Spike Protein Suitable for Multiple Applications for Current Variants of Concern.

The global coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spawned an ongoing demand for new research reagents and interventions. Herein we describe a panel of monoclonal antibodies raised against SARS-CoV-2. One antibody showed excellent utility for immunohistochemistry, clearly staining infected cells in formalin-fixed and paraffin embedded lungs and brains of mice infected with the original and the omicron variants of SARS-CoV-2. We demonstrate the reactivity to multiple variants of concern using ELISAs and describe the use of the antibodies in indirect immunofluorescence assays, Western blots, and rapid antigen tests. Finally, we illustrate the ability of two antibodies to reduce significantly viral tissue titers in K18-hACE2 transgenic mice infected with the original and an omicron isolate of SARS-CoV-2.

2022 SPP Fall Meeting Abstracts

The proceedings contain 57 papers. The topics discussed include: placental cell-specific extracellular vesicle (EV) changes throughout gestation quantitated by nanoscale flow cytometry;eosinophilic/T-cell chorionic vasculitis: a rare but increasingly common placental lesion that does not appear to recur;immunohistochemical interferon gamma expression in chronic Intervillositis of unknown etiology;pathologic lesions attributed to shallow implantation and decidual hypoxia correlate with maternal vascular Malperfusion and related obstetric conditions;comparison of placental pathology reports finalized by generalist pathologists versus perinatal pathology expert: a call to action;a revised placental diagnostic template responds to clinicians' need for outcome and recurrence data;increase in pediatric thrombotic amputations during the SARS-CoV-2 pandemic: manifestation of macrophage activation syndrome;and effectiveness of sigmoidoscopy in disease surveillance of pediatric patients with ulcerative colitis.

SARS-CoV-2-fehérjék kimutatása immunhisztokémiai módszerrel emberi szövetekben.

INTRODUCTION: The COVID-19 (coronavirus disease 2019) caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is associated with high mortality rates worldwide. Polymerase chain reaction (PCR) is extensively used for virus detection in both infected patients and deceased persons. PCR, however, gives no information about the localization of the virus in cells and tissues. Detection of spike and nucleocapsid proteins and viral ribonucleic acid (RNA) of the SARS-CoV-2 in situ might provide more information and aid in the discovery of the pathomechanism of cellular damage. There are several commercially available anti-spike and anti-nucleocapsid antibodies used to detect immunohistochemical reactions, though each gives different results. OBJECTIVE: The goal of the present study was to compare the intensity and specificity of several anti-spike and anti-nucleocapsid antibodies in different dilutions in four Hungarian university departments. METHOD: Immunohistochemical reactions were performed on coded slides taken from infected lungs of 3 deceased and placenta samples with appropriate negative controls of formalin-fixed paraffin-embedded tissues, scanned, evaluated unanimously and analysed statistically by the assessors. RESULTS: By comparing the intensity, dilution, background and reproducibility of the different primary antibodies, it was possible to select the antibodies with the best results. CONCLUSION: The antibodies selected with established dilutions can be used in further studies to detect SARS-CoV-2 proteins in surgical materials and in samples obtained during autopsy. Orv Hetil. 2022; 163(25): 975-983.

Liver pathology in COVID-19 related death and leading role of autopsy in the pandemic.

BACKGROUND: Information on liver involvement in patients with coronavirus disease 2019 is currently fragmented. AIM: To highlight the pathological changes found during the autopsy of severe acute respiratory syndrome coronavirus 2 positive patients. METHODS: A systematic literature search on PubMed was carried out until June 21, 2022. RESULTS: A literature review reveals that pre-existing liver disease and elevation of liver enzyme in these patients are not common; liver enzyme elevations tend to be seen in those in critical conditions. Despite the poor expression of viral receptors in the liver, it seems that the virus is able to infect this organ and therefore cause liver damage. Unfortunately, to date, the search for the virus inside the liver is not frequent (16% of the cases) and only a small number show the presence of the virus. In most of the autopsy cases, macroscopic assessment is lacking, while microscopic evaluation of livers has revealed the frequent presence of congestion (42.7%) and steatosis (41.6%). Less frequent is the finding of hepatic inflammation or necrosis (19%) and portal inflammation (18%). The presence of microthrombi, frequently found in the lungs, is infrequent in the liver, with only 12% of cases presenting thrombotic formations within the vascular tree. CONCLUSION: To date, the greatest problem in interpreting these modifications remains the association of the damage with the direct action of the virus, rather than with the inflammation or alterations induced by hypoxia and hypovolemia in patients undergoing oxygen therapy and decompensated patients.

A Novel Host of an Emerging Disease: SARS-CoV-2 Infection in a Giant Anteater (Myrmecophaga tridactyla) Kept Under Clinical Care in Brazil.

A young male free-ranging giant anteater (Myrmecophaga tridactyla) was found with paralysis of pelvic limbs on a highway and kept under human care. Radiographs confirmed multiple incomplete fractures in the thoracolumbar vertebrae. Due to the poor prognosis, euthanasia was chosen. The infection was established by viral SARS-CoV-2 RNA detection in the rectal swab, spleen and kidney samples. Immunohistochemistry detected the viral nucleocapsid protein in sections of the lungs, liver, spleen, lymph nodes, and large intestine sections, and spike protein antigen in the lung tissue. Pilosa order species should be included as potential hosts of natural infection of SARS-CoV-2.

Determinants of Placental Transfer of HSV-specific Antibodies and the Impact of SARS-CoV-2 Coinfection

Background. Primary versus recurrent herpes simplex virus 1 or 2 (HSV-1 or HSV-2) infection during pregnancy carries a higher risk of neonatal herpes. Murine and clinical studies demonstrate that antibody dependent cellular cytotoxicity (ADCC) provides greater protection against disseminated neonatal disease. To quantify relative transfer of HSV specific Abs with different functions and targets and whether SARS-CoV-2 coinfection modified transfer, we conducted a prospective cohort study of mother-infant dyads prior to and during COVID-19. Methods. Total and HSV lysate, glycoprotein D (gD) and glycoprotein B (gB)-specific IgG, IgG1 and IgG3, nAbs and ADCC were quantified in paired 3rd trimester maternal and cord blood. IgG1 and IgG3 subclass and gD or gB-specific Abs were isolated by column purification and glycan profiles were assessed using mass spectrometry. The pre-COVID study population included 21 term and 15 preterm dyads who were HSV seropositive and the pri-COVID cohort included 25 HSV seropositive term dyads whose mothers were also SARS-CoV-2 PCR and COVID Ab positive at delivery. Results. HSV-specific Ab and neutralizing Ab transfer ratio (TR) were higher in term compared to preterm pre-COVID dyads (all p< 0.05), but the ADCC TR was < 1.0 for both groups. To determine if the low ADCC TR reflected antigenic target, subclass and/or glycans, we enriched for anti-gD and anti-gB specific and IgG1 and IgG3 Abs. The anti-gD Abs were exclusively IgG, had only neutralizing activity and had glycans associated with FcRn binding. In contrast, anti-gB Abs were both IgG1 and IgG3;had both neutralizing and ADCC activity and expressed glycans associated with both FcRn and FcgammaRIIIa binding. There was no significant difference in HSV-specific IgG TR in pre-COVID vs COVID dyads (0.42) but the nAb TR was lower (p=0.018) and ADCC TR higher (p< 0.001) in COVID compared to pre-COVID patients. Placental immunohistochemistry showed an increased colocalization of FcRn and FcgammaRIIIA in SARS-CoV-2 positive mothers, which would favor transfer of ADCC Abs. Conclusion. Defining the determinants of ADCC transfer has implications for future vaccine and monoclonal Ab strategies to prevent/treat neonatal herpes. We speculate that increasing the transfer of ADCC may be a key element in providing immune protection.

Breast Cancer Biopsy Rates in Chile: Is There Justification for Adopting Innovative Anatomic Pathology Technologies in Public Providers?

Objectives: Breast cancer is increasing in Chile, and also the need for biopsies. We aim to identify the evolution of breast cancer diagnosis needs to be measured as Core Needle Biopsy (CNB), Stereotactic Biopsy (SB), Hematoxylin and Eosin staining Histopathological Study (H&ES), Immunohistochemical Study (IS) in relation to echography and mastectomy rates, to understand local needs of adopting innovative pathology technologies in public providers. Method(s): Time-series analysis, based on an open-access national database for the following variables: CNB, SB, H&ES, IS, echography, and mastectomy for a decade (2010-2021). The data is representative of the national activity in public providers, for which the intra-period variation and median-growth rate (MGR) were estimated. Result(s): CNB experimented a 630.7% increase in the period (MGR 19.8%). SB increased 92.3% at an MGR of 6.1%. H&ES and IS increased 19.1% and 379.4% (MRG 1.6% and 15.3% respectively). Lumpectomy and Radical Mastectomies (RM) behaved differently. Lumpectomy varied in 31.2% (MGR of 2.5%) whereas RM varied in -13.6% (negative MGR -1.3%). The covid-19 pandemic significantly decreased activity for SB, lumpectomies, and RM (p <0.05). Echography exhibits an increase of 27.5% (MGR 6.3% per year). The biopsy versus surgeries ratio was estimated, resulting in a variation from 0.537 in 2011 to 1.9 in 2021;this is 1.9 biopsies per surgery in the public system. Conclusion(s): Anatomic pathology based-analysis in breast cancer has increased in the last decade in Chile. The ratio of biopsy versus surgery has changed dramatically, pushing for innovation in the process of analysis of samples in a local setting of pathologist scarcity (1.22 pathologist per 100,000 public patients). Copyright © 2022

Clinical Profile, Treatment and Outcome of Pediatric ''Coffee Bean'' Histiocytosis: A Single Center Experience

Introduction: Langerhans Cell Histiocytosis is a group of diseases with a myriad of clinical manifestations and biological behavior, characterized by proliferation and accumulation of Langerhans cells in different organs. Aims & Objectives: This study is to demonstrate the varied clinical presentations and the treatment outcome of the children in one of the few pediatriccenters in North India that cater to various benign and malignant blood disorders of children. Material(s) and Method(s): The study describes the 4-year experience of our center in managing children with LCH. The clinical presentations, relevant laboratory, and radiological findings, treatment, and outcome of all the 14 children presenting between December 2018 and August 2022 were retrieved from our Hospital Information system. The LCH IV protocol was taken as the backbone for classification, risk organ involvement, stratum allocation, for deciding on treatment strategy, treatment response, and outcome. Result(s): A total of 14 children were diagnosed with LCH during the study period. The mean age at diagnosis was 36 months(range: 10-110 months, median: 34 months). The male: female ratio was 9:5. 12 children had multisystem LCH while 2 children had single system LCH. Lymphadenopathy was the most common clinical presentation while the skeletal system was the most common system involved, affecting 64% of the children. There were a total of 8(57%) children who were in complete remission, of which 1 child expired and one relapsed, though went into the second remission. One child had a progressive disease. Three(21%) children left against medical advice while 1 child abandoned treatment 2 weeks into therapy. One of the children became covid positive after diagnosis and expired before the treatment could be initiated. Conclusion(s): The wide array of clinical manifestations warrants the need for a high index of suspicion for an earlier diagnosis of LCH. The morphological identification of Langerhan's cells and positive IHC for CD1a, S100, and/or CD207 are necessary for definitive diagnosis. All patients with LCH should undergo BRAF-V600E mutational testing to aid in diagnosis and treatment.

Ultrastructural Changes in Autopsy Tissues of COVID-19 Patients.

INTRODUCTION: The COVID-19 pandemic resulted in substantial morbidity and mortality across the world. The prognosis was found to be poor in patients with co-morbidities such as diabetes, hypertension, interstitial lung disease, etc. Although biochemical studies were done in patient samples, no study has been reported from the Indian subcontinent about ultrastructural changes in the vital organs of COVID-19 patients. The present study was, therefore, conducted to understand the ultrastructural changes in the lung, liver, and brain of the deceased patients. METHODS: The present study was conducted on samples obtained from reverse transcription-polymerase chain reaction (RT-PCR)-positive patients who were admitted to a tertiary care hospital in Western India. Core needle biopsies were done in eight fatal cases of COVID-19. The samples were taken from the lungs, liver, and brain and subjected to light microscopy, immunohistochemistry (IHC), and transmission electron microscopy (TEM). Clinical details and biochemical findings were also collected.  Results: The study participants included seven males and one female. The presenting complaints included fever, breathlessness, and cough. Light microscopy revealed diffuse alveolar damage in the lungs. Further, a positive expression of SARS-CoV-2 nucleocapsid protein was observed in the pulmonary parenchyma of five patients. Also, the TEM microphotograph showed viral particles of size up to 80nm localized in alveolar epithelial cells. However, no viral particles were found in liver or brain samples. In the liver, macrovesicular steatosis and centrizonal congestion with loss of hepatocytes were observed in light microscopy. CONCLUSION:  This is the first study in the Indian population showing the in-situ presence of viral particles in core biopsies from fatal cases of COVID-19. As evident from the results, histology and ultrastructural changes in the lung correlated with the presence of viral particles. The study revealed a positive correlation between the damage in the lungs and the presence of viral particles.

Liver alterations and detection of SARS-CoV-2 RNA and proteins in COVID-19 autopsies.

The most severe alterations in Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) infection are seen in the lung. However, other organs also are affected. Here, we report histopathologic findings in the liver and detection of viral proteins and RNA in COVID-19 autopsies performed at the Semmelweis University (Budapest, Hungary). Between March 2020 through March 2022, 150 autopsies on patients who died of COVID-19 were analyzed. Cause-of-death categories were formed based on the association with SARS-CoV-2 as strong, contributive, or weak. Samples for histopathologic study were obtained from all organs, fixed in formalin, and embedded in paraffin (FFPE). Immunohistochemical study (IHC) to detect SARS-CoV-2 spike protein and nucleocapsid protein (NP), CD31, claudin-5, factor VIII, macrosialin (CD68), and cytokeratin 7, with reverse transcriptase polymerase chain reaction (RT-PCR), and in situ hybridization (ISH, RNAscope®) for SARS-CoV-2 RNA were conducted using FFPE samples of livers taken from 20 autopsies performed ≤ 2 days postmortem. All glass slides were scanned; the digital images were evaluated by semiquantitative scoring and scores were analyzed statistically. Steatosis, single-cell and focal/zonal hepatocyte necrosis, portal fibrosis, and chronic inflammation were found in varying percentages. Sinusoidal ectasia, endothelial cell disruption, and fibrin-filled sinusoids were seen in all cases; these were assessed semiquantitatively for severity (SEF scored). SEF scores did not correlate with cause-of-death categories (p = 0.92) or with severity of lung alterations (p = 0.96). SARS-CoV-2 RNA was detected in 13/20 cases by PCR and in 9/20 by ISH, with IHC demonstration of spike protein in 4/20 cases and NP in 15/20. Viral RNA and proteins were located in endothelial and Kupffer cells, and in portal macrophages, but not in hepatocytes and cholangiocytes. In conclusion, endothelial damage (SEF scores) was the most common alteration in the liver and was a characteristic, but not specific alteration in COVID-19, suggesting an important role in the pathogenesis of COVID-19-associated liver disease. Detection of SARS-CoV-2 RNA and viral proteins in liver non-parenchymal cells suggests that while the most extended primary viral cytotoxic effect occurs in the lung, viral components are present in other organs too, as in the liver. The necrosis/apoptosis and endothelial damage associated with viral infection in COVID-19 suggest that those patients who survive more severe COVID-19 may face prolonged liver repair and accordingly should be followed regularly in the post-COVID period.

Factor XII activation by NET accumulation aggravates COVID-19- associated pulmonary thrombo-inflammation

Background: Coagulopathy and inflammation are hallmarks of COVID-19 and are associated with increased mortality. Clinical and experimental data have revealed a role for neutrophil extracellular traps (NETs) in COVID-19. Mechanisms that drive thrombo-inflammation in COVID-19 are poorly understood. Aim(s): In this study, we aimed to investigate a possible role of NETs-driven coagulation factor XII (FXII) activation in COVID-19- related thrombo-inflammation. Method(s): We performed comprehensive proteomics and immunostaining of postmortem lung tissues from COVID-19 patients and patients with other lung pathologies. We compared FXII and DNase1 activities in plasma samples from COVID-19 patients and healthy control donors and determined NET-induced FXII activation using a chromogenic substrate assay. Result(s): FXII expression and activity were increased in the lung parenchyma, within the pulmonary vasculature and in fibrin-rich alveolar spaces of postmortem lung tissues from COVID-19 patients over controls. Active FXII (FXIIa) was increased in plasma of COVID-19 patients. Furthermore, FXIIa colocalized with NETs in COVID-19 lung tissue indicating that NETs accumulation leads to FXII activation in COVID-19. Accumulation of NETs in COVID-19 was at least in parts due to impaired DNA clearance by extracellular DNases. In plasma from COVID-19 patients, DNase1 substitution improved NET dissolution and reduced FXII activation in vitro. Conclusion(s): Collectively, our study shows that the NETs/FXIIa axis contributes to procoagulant and proinflammatory reactions in COVID-19. Targeting NETs and FXIIa may offer a potential therapeutic strategy for interfering with the COVID-19 lung pathology.

Inmunohistochemical detection of pandemic SARSCoV- 2 antigens in lung tissue. / Detección inmunohistoquímica de antígenos de SARS-CoV-2 en tejido pulmonar

The COVID-19 pandemic caused by the SARS-CoV-2 virus has generated globally more than 110.7 million infections and 2.4 million deaths. The severity of this infection can range from asymptomatic, mild to severe. To know the possible associations between the presence of the virus and histopathological alterations found in tissues of fatal cases of COVID-19, the presence of the virus in the lung tissue of a patient with a clinical history of SARS-CoV-2 infection was evaluated. Lung tissue was histologically processed for immunohistochemical detection of SARSCoV-2. In the histopathological study, morphological changes associated with pneumonitis of viral origin were observed. Likewise, the location of the SARS-CoV-2 virus was observed mainly in the cytoplasm of the cells of the inflammatory infiltrate.

La pandemia de COVID-19 causada por el virus SARS-CoV-2 ha generado más de 110,7 millones de infecciones y 2,4 millones de muertes a nivel mundial. Esta infección puede ser asintomática y sus manifestaciones clínicas pueden variar entre leves y graves. Para conocer las posibles asociaciones entre la presencia del virus y las alteraciones histopatológicas encontradas en los tejidos de casos fatales de COVID-19, se evaluó la presencia del virus en el tejido pulmonar de un paciente con antecedentes clínicos de infección por SARS-CoV-2. La muestra se procesó para la detección inmunohistoquímica del virus. En el estudio histopatológico, se observaron cambios morfológicos asociados con neumonitis de origen viral. Asimismo, el virus se localizó principalmente en el citoplasma de las células del infiltrado inflamatorio.

Lung Inflammasome Activation in SARS-CoV-2 Post-Mortem Biopsies.

The inflammasome complex is a key part of chronic diseases and acute infections, being responsible for cytokine release and cell death mechanism regulation. The SARS-CoV-2 infection is characterized by a dysregulated cytokine release. In this context, the inflammasome complex analysis within SARS-CoV-2 infection may prove beneficial to understand the disease's mechanisms. Post-mortem minimally invasive autopsies were performed in patients who died from COVID-19 (n = 24), and lung samples were compared to a patient control group (n = 11) and an Influenza A virus H1N1 subtype group from the 2009 pandemics (n = 10). Histological analysis was performed using hematoxylin-eosin staining. Immunohistochemical (IHC) staining was performed using monoclonal antibodies against targets: ACE2, TLR4, NF-κB, NLRP-3 (or NALP), IL-1ß, IL-18, ASC, CASP1, CASP9, GSDMD, NOX4, TNF-α. Data obtained from digital analysis underwent appropriate statistical tests. IHC analysis showed biomarkers that indicate inflammasome activation (ACE2; NF-κB; NOX4; ASC) were significantly increased in the COVID-19 group (p < 0.05 for all) and biomarkers that indicate cell pyroptosis and inflammasome derived cytokines such as IL-18 (p < 0.005) and CASP1 were greatly increased (p < 0.0001) even when compared to the H1N1 group. We propose that the SARS-CoV-2 pathogenesis is connected to the inflammasome complex activation. Further studies are still warranted to elucidate the pathophysiology of the disease.

Corrigendum: Case report: Persistence of residual antigen and RNA of the SARS-CoV-2 virus in tissues of two patients with long COVID.

[This corrects the article DOI: 10.3389/fimmu.2022.939989.].

Asymptomatic SARS-CoV-2 Infection in Children's Tonsils

Introduction: The SARS-CoV-2 pandemic killed over 6 million people worldwide. Children were described to have predominantly mild or asymptomatic infections and to be less exposed to the virus, at least for the initial variants. In the present study, we describe how SARS-CoV-2 can silently infect tonsils and adenoids in children undergoing adenotonsillectomy. Method(s): In this cross-sectional study we assessed children who underwent adenotonsillectomy between October 2020 and September 2021 in a secondary hospital in Brazil. All the caregivers denied any symptom of acute viral upper airway infection in the month prior to surgery. Briefly, nasal cytobrush (NC), nasal wash (NW) and tonsillar tissue fragments posttonsillectomy were tested by RT-PCR, immunohistochemistry (IHC), in situ immunofluorescence (IF), and flow cytometry. Result(s): A total of 48 children (18 females, median age 5.5 years) were enrolled. None of them had been vaccinated against COVID-19 at the time of surgery. Only 2 had a history of previous COVID-19 diagnosis, 3 and 5 months, respectively, before surgery. SARS-CoV-2 RNA was detected in 25% (12) of patients-20% in palatine tonsils, 16.27% in the adenoids, 10.41% in NC, and 6.25% in NW. IHC labeling showed viral nucleoprotein presence in both adenoids and palatine tonsils, in epithelial surface and lymphoid cells from extrafollicular and follicular regions. In 5 out of 7 patients, in situ IF showed the expression of ACE2 and TMPRSS2 and viral spike protein in the tonsillar tissue. Flow cytometry revealed that SARS-CoV-2 is predominantly observed in CD123+ dendritic cells (10.57% of all tested sites), followed by CD14+ monocytes (6.32%). Conclusion(s): According to these results, the prevalence of SARS-CoV-2 infection seems to be higher than expected and underdiagnosed in children at this age group. Palatine tonsils and adenoids are important sites of infection and may be a reservoir for the virus. Nevertheless, it is still unclear the impact of these results on virus transmission.