Pulmonary changes in Norwegian fatal cases of pandemic influenza H1N1 (2009) infection: a morphologic and molecular genetic study

Immunohistochemical diagnosis of human infectious diseases: a review

BACKGROUND

Immunohistochemistry (IHC) using monoclonal and polyclonal antibodies is a useful diagnostic method for detecting pathogen antigens in fixed tissues, complementing the direct diagnosis of infectious diseases by PCR and culture on fresh tissues. It was first implemented in a seminal publication by Albert Coons in 1941.

MAIN BODY

Of 14,198 publications retrieved from the PubMed, Google, Google Scholar and Science Direct databases up to December 2021, 230 were selected for a review of IHC techniques, protocols and results. The methodological evolutions of IHC and its application to the diagnosis of infectious diseases, more specifically lice-borne diseases, sexually transmitted diseases and skin infections, were critically examined. A total of 59 different pathogens have been detected once in 22 different tissues and organs; and yet non-cultured, fastidious and intracellular pathogens accounted for the vast majority of pathogens detected by IHC. Auto-IHC, incorporating patient serum as the primary antibody, applied to diseased heart valves surgically collected from blood culture-negative endocarditis patients, detected unidentified Gram-positive cocci and microorganisms which were subsequently identified as Coxiella burnetii, Bartonella quintana, Bartonella henselae and Tropheryma whipplei. The application of IHC to ancient tissues dated between the ends of the Ptolemaic period to over 70 years ago, have also contributed to paleomicrobiology diagnoses.

CONCLUSION

IHC plays an important role in diagnostic of infectious diseases in tissue samples. Paleo-auto-IHC derived from auto-IHC, is under development for detecting non-identified pathogens from ancient specimens.

Pathophysiology of Acute Respiratory Failure by CoV-2 Infection: Role of Oxidative Stress, Endothelial Dysfunction and Obesity

Coronavirus disease 2019 (COVID-19) due to CoV-2 (coronavirus type 2) virus possess a particular risk of developing acute respiratory distress syndrome (ARDS) or SARS (severe acute respiratory syndrome coronavirus 2)-CoV2 in people with pre-existing conditions related to endothelial dysfunction and increased pro-inflammatory and pro-oxidant state. In between these conditions, chronic systemic inflammation related to obese patients is associated with the development of atherosclerosis, type 2 diabetes, and hypertension, comorbidities that adversely affect the clinical outcome in critical patients with COVID-19. Obesity affects up to 40% of the general population in the USA and more than 30% of the adult population in Chile. Until April 2021, 1,019,478 people have been infected, with 23,524 deaths. Given the coexistence of this worldwide obesity epidemic, COVID-19 negative outcomes are seriously enhanced in the current scenario. On the other hand, obesity is characterized by endothelial dysfunction observed in different vascular beds, an alteration which can be associated with impaired vasodilation, oxidative stress, and inflammatory events. Emerging evidence shows that obesity-related conditions such as endothelial dysfunction are associated with detrimental outcomes for COVID-19 evolution, especially if the patient derives to Intensive Care Units (ICU). This implies the need to understand the pathophysiology of the infection in the obese population, in order to propose therapeutic alternatives and public health policies, especially if the virus remains in the population. In this review, we summarize evidence about the pathogeny of Cov-2 infection in obese individuals and discuss how obesity-associated inflammatory and prooxidant status increase the severity of COVID-19.

Pathophysiology of SARS-CoV-2: the Mount Sinai COVID-19 autopsy experience

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated clinical syndrome COVID-19 are causing overwhelming morbidity and mortality around the globe and disproportionately affected New York City between March and May 2020. Here, we report on the first 100 COVID-19-positive autopsies performed at the Mount Sinai Hospital in New York City. Autopsies revealed large pulmonary emboli in six cases. Diffuse alveolar damage was present in over 90% of cases. We also report microthrombi in multiple organ systems including the brain, as well as hemophagocytosis. We additionally provide electron microscopic evidence of the presence of the virus in our samples. Laboratory results of our COVID-19 cohort disclose elevated inflammatory markers, abnormal coagulation values, and elevated cytokines IL-6, IL-8, and TNFα. Our autopsy series of COVID-19-positive patients reveals that this disease, often conceptualized as a primarily respiratory viral illness, has widespread effects in the body including hypercoagulability, a hyperinflammatory state, and endothelial dysfunction. Targeting of these multisystemic pathways could lead to new treatment avenues as well as combination therapies against SARS-CoV-2 infection.

Autopsies in pandemics - a perspective on barriers and benefits. Is it time for a revival?

Influenza virus and coronavirus pandemics regularly sweep the globe, at great cost of health and economy. Our aim was to conduct a PubMed search for autopsy studies on influenza and coronavirus to investigate the contribution of autopsies during pandemics, focussing on autopsy methods and procedures and the role of autopsy findings in pandemics. The retrieved autopsy studies generally relied on microscopy, polymerase chain reaction (PCR), immunostaining and electron microscopy. Most were small and reported on lung effects, including diffuse alveolar damage (DAD), pneumonia and tracheobronchitis. Antibiotic therapy has diminished a role for bacterial pneumonia, whereas obesity is an emerging risk factor. Autopsy studies have provided new insights into coronavirus disease 2019 (COVID‐19) treatments like anti‐coagulative therapy. Unfortunately, autopsies during pandemics are hampered by lack of guidelines, facilities and expertise for handling potentially infectious corpses and by widely varying recommendations for personal protective equipment and procedures. The Department of Forensic Pathology, at the Forensic Institute, at the University of Copenhagen in Denmark has, in collaboration with the Department of Pathology, Rigshospitalet, Copenhagen, initiated a prospective observational study on COVID‐19‐related deaths encompassing postmortem imaging, standardized autopsy procedures/reporting and extensive tissue sampling for histological, chemical, microbiological and genetic analysis. The study involves a diverse array of research groups at the University of Copenhagen, and the clinical field.

[Organ changes found by postmortem examination in COVID-19 patients]

The postmortem study results presented in 20 sources of literature on 186 COVID-19 patients were analyzed. Pathological changes were noted in multiple organs, by involving predominantly the respiratory, circulatory, and excretory systems. The changes in the lungs were characterized by an increase in organ weight (59.3%), a dark red color of the parenchyma (47.4%), compaction of lung tissue (56%), and signs of lung congestion (37.3%). The histological characteristics found during postmortem lung tissue examination, which were indicative of diffuse alveolar damage, were proliferation of type II alveolocytes in 65.2% of cases, the appearance of hyaline membranes lining the alveoli in 64.4%, and interstitial edema in 54.2%. In the analyzed sources, 22% of cases were noticed to have severe thrombosis and pulmonary artery branch embolism that was associated with lower extremity deep vein thrombosis. In all the sources of literature, acute tubular necrosis, tubular luminal dilatation, and interstitial edema were detected in the kidneys.

SARS-CoV-2-related lung pathology: macroscopic and histologic features and their clinical implications

The ongoing global coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been posing challenges to proper patients' management. Lungs are the first, and often the most affected organ by SARS-CoV-2; viral infection involves and damages both epithelial and vascular compartments, sometimes leading to severe and even fatal acute respiratory distress syndrome. Histopathological findings, mainly from postmortem examination of COVID-19 deceased patients, have been increasingly published in the last few months, helping to elucidate the sequence of events resulting in organ injury, and the complex multifactorial pathogenesis of this novel disease. A multidisciplinary approach to autopsy, including light microscopy examination along with the detection of viral proteins and/or RNA in tissue samples through ancillary techniques, provided crucial information on the mechanisms underlying the often-heterogeneous clinical picture of COVID-19.

Pulmonary Vascular Endothelialitis, Thrombosis, and Angiogenesis in Covid-19

BACKGROUND

Progressive respiratory failure is the primary cause of death in the coronavirus disease 2019 (Covid-19) pandemic. Despite widespread interest in the pathophysiology of the disease, relatively little is known about the associated morphologic and molecular changes in the peripheral lung of patients who die from Covid-19.

METHODS

We examined 7 lungs obtained during autopsy from patients who died from Covid-19 and compared them with 7 lungs obtained during autopsy from patients who died from acute respiratory distress syndrome (ARDS) secondary to influenza A(H1N1) infection and 10 age-matched, uninfected control lungs. The lungs were studied with the use of seven-color immunohistochemical analysis, micro-computed tomographic imaging, scanning electron microscopy, corrosion casting, and direct multiplexed measurement of gene expression.

RESULTS

In patients who died from Covid-19-associated or influenza-associated respiratory failure, the histologic pattern in the peripheral lung was diffuse alveolar damage with perivascular T-cell infiltration. The lungs from patients with Covid-19 also showed distinctive vascular features, consisting of severe endothelial injury associated with the presence of intracellular virus and disrupted cell membranes. Histologic analysis of pulmonary vessels in patients with Covid-19 showed widespread thrombosis with microangiopathy. Alveolar capillary microthrombi were 9 times as prevalent in patients with Covid-19 as in patients with influenza (P<0.001). In lungs from patients with Covid-19, the amount of new vessel growth - predominantly through a mechanism of intussusceptive angiogenesis - was 2.7 times as high as that in the lungs from patients with influenza (P<0.001).

CONCLUSIONS

In our small series, vascular angiogenesis distinguished the pulmonary pathobiology of Covid-19 from that of equally severe influenza virus infection. The universality and clinical implications of our observations require further research to define. (Funded by the National Institutes of Health and others.).

Pulmonary Vascular Manifestations of COVID-19 Pneumonia

PURPOSE

To investigate pulmonary vascular abnormalities at CT pulmonary angiography (CT-PE) in patients with coronavirus disease 2019 (COVID-19) pneumonia.

MATERIALS AND METHODS

In this retrospective study, 48 patients with reverse-transcription polymerase chain reaction-confirmed COVID-19 infection who had undergone CT-PE between March 23 and April 6, 2020, in a large urban health care system were included. Patient demographics and clinical data were collected through the electronic medical record system. Twenty-five patients underwent dual-energy CT (DECT) as part of the standard CT-PE protocol at a subset of the hospitals. Two thoracic radiologists independently assessed all studies. Disagreement in assessment was resolved by consensus discussion with a third thoracic radiologist.

RESULTS

Of the 48 patients, 45 patients required admission, with 18 admitted to the intensive care unit, and 13 requiring intubation. Seven patients (15%) were found to have pulmonary emboli. Dilated vessels were seen in 41 cases (85%), with 38 (78%) and 27 (55%) cases demonstrating vessel enlargement within and outside of lung opacities, respectively. Dilated distal vessels extending to the pleura and fissures were seen in 40 cases (82%) and 30 cases (61%), respectively. At DECT, mosaic perfusion pattern was observed in 24 cases (96%), regional hyperemia overlapping with areas of pulmonary opacities or immediately surrounding the opacities were seen in 13 cases (52%), opacities associated with corresponding oligemia were seen in 24 cases (96%), and hyperemic halo was seen in 9 cases (36%).

CONCLUSION

Pulmonary vascular abnormalities such as vessel enlargement and regional mosaic perfusion patterns are common in COVID-19 pneumonia. Perfusion abnormalities are also frequently observed at DECT in COVID-19 pneumonia and may suggest an underlying vascular process.Supplemental material is available for this article.© RSNA, 2020.

Molecular influenza surveillance at a tertiary university hospital during four consecutive seasons (2012-2016) in Catalonia, Spain

BACKGROUND

Influenza viruses (FLUV) are continuously evolving, which explain the occurrence of seasonal influenza epidemics and the need to review the vaccine strain composition annually. The aim is to describe the genetic diversity and clinical outcomes of FLUV detected at a tertiary university hospital in Barcelona (Spain) during the 2012-2016 seasons.

METHODS

The detection of FLUV from patients attended at the Emergency Department or admitted to the hospital was performed by either immunofluorescence or PCR-based assays. A specific real-time one-step multiplex RT-PCR was performed for influenza A (FLUAV) subtyping. The complete coding haemagglutinin domain 1 (HA1) and neuraminidase (NA) (2015-2016) protein sequences from a representative sampling were molecular characterised.

RESULTS

A total 1774 (66.1%) FLUAV and 910 (33.9%) influenza B (FLUBV) cases were laboratory-confirmed. The hospitalisation rate was different between seasons, being the highest (81.4%) during the 2014-2015 season. FLUV were genetically close to vaccine strains except to the 2014-2015, in which most characterised A(H3N2) viruses belonged to a genetic group different from the vaccine strain. During the 2015-2016 season, B/Victoria-like viruses were the most predominant, but this component was not included in the trivalent vaccine used. Mutations D222G or D222N in HA1-domain were found in 3 A(H1N1)pdm09 strains from ICU-admitted cases. Three A(H1N1)pdm09 strains carried the NA H275Y (2) and S247N (1) mutations, respectively related to resistance or decreased susceptibility to oseltamivir.

CONCLUSIONS

The circulation of drifted A(H3N2) strains during the 2014-2015 season was related to the high hospitalisation rate due to the mismatch with the vaccine strains. The predominance of a FLUBV lineage not included in the trivalent influenza vaccine during the 2015-2016 season highlights the need to use a tetravalent influenza vaccine. Virological surveillance of viral variants carrying protein changes that alter tropism and susceptibility to antivirals features should be strengthened in hospital settings.

Pulmonary changes in Norwegian fatal cases of pandemic influenza H1N1 (2009) infection: a morphologic and molecular genetic study

Background

During the pandemic outbreak of the 2009 swine influenza (A(H1N1)pdm09), 32 fatal cases occurred in Norway and 19 of these were included in this study.

Objectives

We characterised pulmonary changes in these fatal Norwegian cases.

Patients and Methods

Upon hospitalisation, detailed clinical information and specimens from the upper and lower respiratory pathways were collected. At post‐mortem, lung tissue was collected, formalin‐fixed and paraffin‐embedded. Immunohistochemical and light microscopic examination was performed to visualise the local expression of the A(H1N1)pdm09 virus. Reverse transcription‐polymerase chain reaction (RT‐PCR) and pyrosequencing of the non‐fixed specimens allowed the identification of mutations in the influenza virus surface glycoprotein (haemagglutinin gene) particularly at position 222.

Results and Conclusions

The overall course of illness lasted from 2 to 40 days (median 9 days). Diffused alveolar damage (DAD) was evident in 11 cases, 4 of which had no apparent underlying illness. Obesity was prominent in 12 cases, where three individuals were classified as otherwise healthy. The HA D222G mutation was detected in six cases, 3 of which had no underlying illness. Immunohistochemistry showed the A(H1N1)pdm09 virus to be prominent at the site of inflammation both in close proximity to and inside alveolar structures in the lung tissue. In addition to a possible role for the HA D222G mutation, our findings indicate that host factors and underlying conditions in the infected individuals are fundamental for disease outcome in many cases. This study increases our understanding of determinants for the clinical outcome of pandemic influenza, which could guide future treatment.