Evidence of SARS-CoV-2 infection in postmortem lung, kidney, and liver samples, revealing cellular targets involved in COVID-19 pathogenesis

There is an urgent need to understand severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-host interactions involved in virus spread and pathogenesis, which might contribute to the identification of new therapeutic targets. In this study, we investigated the presence of SARS-CoV-2 in postmortem lung, kidney, and liver samples of patients who died with coronavirus disease (COVID-19) and its relationship with host factors involved in virus spread and pathogenesis, using microscopy-based methods. The cases analyzed showed advanced stages of diffuse acute alveolar damage and fibrosis. We identified the SARS-CoV-2 nucleocapsid (NC) in a variety of cells, colocalizing with mitochondrial proteins, lipid droplets (LDs), and key host proteins that have been implicated in inflammation, tissue repair, and the SARS-CoV-2 life cycle (vimentin, NLRP3, fibronectin, LC3B, DDX3X, and PPARγ), pointing to vimentin and LDs as platforms involved not only in the viral life cycle but also in inflammation and pathogenesis. SARS-CoV-2 isolated from a patient´s nasal swab was grown in cell culture and used to infect hamsters. Target cells identified in human tissue samples included lung epithelial and endothelial cells; lipogenic fibroblast-like cells (FLCs) showing features of lipofibroblasts such as activated PPARγ signaling and LDs; lung FLCs expressing fibronectin and vimentin and macrophages, both with evidence of NLRP3- and IL1β-induced responses; regulatory cells expressing immune-checkpoint proteins involved in lung repair responses and contributing to inflammatory responses in the lung; CD34⁺ liver endothelial cells and hepatocytes expressing vimentin; renal interstitial cells; and the juxtaglomerular apparatus. This suggests that SARS-CoV-2 may directly interfere with critical lung, renal, and liver functions involved in COVID-19-pathogenesis.

The microglial NLRP3 inflammasome is involved in human SARS-CoV-2 cerebral pathogenicity: A report of three post-mortem cases

We herein report, by using confocal immunofluorescence, the colocalization of the SARS-CoV-2 nucleocapsid within neurons, astrocytes, oligodendrocytes and microglia in three deceased COVID-19 cases, of between 78 and 85 years of age at death. The viral nucleocapsid was detected together with its ACE2 cell entry receptor, as well as the NLRP3 inflammasome in cerebral cortical tissues. It is noteworthy that NLRP3 was colocalized with CD68 + macrophages in the brain and lung of the deceased, suggesting the critical role of this type of inflammasome in SARS-CoV-2 lesions of the nervous system/lungs and supporting its potential role as a therapeutic target.

Epidemic neuropathy in Cuba: morphological characterization of peripheral nerve lesions in sural nerve biopsies

More than 50,000 patients were affected in Cuba during an epidemic outbreak of peripheral neuropathy from January 1992 until September 1993. The disease presented as either a retrobulbar optic neuropathy, a predominantly sensory peripheral neuropathy, a dorsolateral myeloneuropathy, or as mixed forms. The morphological findings in sural nerve biopsies from 34 patients with various forms of the disease are presented here. Frozen, paraffin and semi-thin sections were prepared for light and electron microscopy, immunohistochemistry and morphometric analysis. Every case presented morphological alterations ranging from mild axonal dystrophy (9 cases, or 27%) to moderate and severe axonal damage (25 cases, or 73%). In 6 cases (18%), axonal damage was accompanied by perineural fibrosis and vascular abnormalities. Axonal regeneration was noted in 8 cases (23%) and remyelination in 9 (26%). Morphometric analysis showed a predominant loss of myelinated fibers in 92% of the patients. Quantification of myelinated fiber loss in 11 patients revealed a remarkable decrease in large caliber fibers. Scarce mononuclear cells were observed in 17 cases. No virus-like elements were seen. The morphological features found in this study indicate that, regardless of the clinical presentation, peripheral nerve lesions of the epidemic neuropathy in Cuba correspond to an axonal neuropathy. These lesions are compatible with nutritional, toxic, or metabolic etiologies. An inflammatory etiology would be unusual with these lesions.

[Cutaneous larva migrans. Report of a case]

A 20-year-old female patient who presented papylo-erythematous lesions with intense pruritus and arciform sinuous lesions in the back and gluteal regions during a stay at a beach is presented. A cutaneous larva migrans was diagnosed through biopsy. A brief bibliographic review of this parasitologic entity is made.