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

MiR-155-targeted IcosL controls tumor rejection

Elevated levels of miR-155 in solid and liquid malignancies correlate with aggressiveness of the disease. In this manuscript, we show that miR-155 targets transcripts encoding IcosL, the ligand for Inducible T-cell costimulator (Icos), thus impairing the ability of T cells to recognize and eliminate malignant cells. We specifically found that overexpression of miR-155 in B cells of Eµ-miR-155 mice causes loss of IcosL expression as they progress toward malignancy. Similarly, in mice where miR-155 expression is controlled by a Cre-Tet-OFF system, miR-155 induction led to malignant infiltrates lacking IcosL expression. Conversely, turning miR-155 OFF led to tumor regression and emergence of infiltrates composed of IcosL-positive B cells and Icos-positive T cells forming immunological synapses. Therefore, we next engineered malignant cells to express IcosL, in order to determine whether IcosL expression would increase tumor infiltration by cytotoxic T cells and reduce tumor progression. Indeed, overexpressing an IcosL-encoding cDNA in MC38 murine colon cancer cells before injection into syngeneic C57BL6 mice reduced tumor size and increased intratumor CD8+ T cell infiltration, that formed synapses with IcosL-expressing MC38 cells. Our results underscore the fact that by targeting IcosL transcripts, miR-155 impairs the infiltration of tumors by cytotoxic T cells, as well as the importance of IcosL on enhancing the immune response against malignant cells. These findings should lead to the development of more effective anticancer treatments based on maintaining, increasing, or restoring IcosL expression by malignant cells, along with impairing miR-155 activity.

A Series of 69 COVID-related Dermatoses With Biopsy, Immunohistochemistry With Anti-spike 3, in situ Hybridization and PCR: A Critical Reappraisal of Viral Involvement in COVID-19 Skin Lesions

BACKGROUND

Despite the large number of articles published on skin lesions related to COVID-19, clinicopathological correlation has not been performed consistently and immunohistochemistry to demonstrate spike 3 protein expression has not been validated through RT-PCR.

MATERIAL AND METHODS

We compiled 69 cases of patients with confirmed COVID-19, where skin lesions were clinically and histopathologically studied. Immunohistochemistry (IHC) and RT-PCR was performed in skin biopsies.

RESULTS

After a careful review of the cases, 15 were found to be dermatosis not related to COVID-19, while the rest of the lesions could be classified according to their clinical characteristics as vesicular (4), maculopapular eruptions (41), urticariform (9), livedo and necrosis (10) and pernio-like (5). Although histopathological features were similar to previously reported results, we found two previously unreported findings, maculopapular eruptions with squamous eccrine syringometaplasia and neutrophilic epitheliotropism. IHC showed in some cases endothelial and epidermal staining but RT-PCR was negative in all the tested cases. Thus, direct viral involvement could not be demonstrated.

CONCLUSIONS

Despite presenting the largest series of confirmed COVID-19 patients with histopathologically studied skin manifestations, direct viral involvement was difficult to establish. Vasculopathic and urticariform lesions seem to be those more clearly related to the viral infection, despite IHC or RT-PCR negative results failed to demonstrate viral presence. These findings, as in other dermatological areas, highlight the need of a clinico-pathological correlation to increase knowledge about viral involvement in COVID-19 skin-related lesions.

A Series of 69 COVID-related Dermatoses With Biopsy, Immunohistochemistry With Anti-spike 3, in situ Hybridization and PCR: A Critical Reappraisal of Viral Involvement in COVID-19 Skin Lesions

BACKGROUND

Despite the large number of articles published on skin lesions related to COVID-19, clinicopathological correlation has not been performed consistently and immunohistochemistry to demonstrate spike 3 protein expression has not been validated through RT-PCR.

MATERIAL AND METHODS

We compiled 69 cases of patients with confirmed COVID-19, where skin lesions were clinically and histopathologically studied. Immunohistochemistry (IHC) and RT-PCR was performed in skin biopsies.

RESULTS

After a careful review of the cases, 15 were found to be dermatosis not related to COVID-19, while the rest of the lesions could be classified according to their clinical characteristics as vesicular (4), maculopapular eruptions (41), urticariform (9), livedo and necrosis (10) and pernio-like (5). Although histopathological features were similar to previously reported results, we found two previously unreported findings, maculopapular eruptions with squamous eccrine syringometaplasia and neutrophilic epitheliotropism. IHC showed in some cases endothelial and epidermal staining but RT-PCR was negative in all the tested cases. Thus, direct viral involvement could not be demonstrated.

CONCLUSIONS

Despite presenting the largest series of confirmed COVID-19 patients with histopathologically studied skin manifestations, direct viral involvement was difficult to establish. Vasculopathic and urticariform lesions seem to be those more clearly related to the viral infection, despite IHC or RT-PCR negative results failed to demonstrate viral presence. These findings, as in other dermatological areas, highlight the need of a clinico-pathological correlation to increase knowledge about viral involvement in COVID-19 skin-related lesions.

The rapid diagnosis of Mycoplasma pneumonia using in situ hybridization on clinical samples

The microbiological etiology of seasonal upper respiratory illnesses in the United States is dominated by viruses, including influenza A, B, respiratory syncytial virus, and SARS-CoV2. Mycoplasma pneumonia, treatable with antibiotics, can also cause upper respiratory symptoms and is typically associated with about 15 % of cases. There is no clinical or radiologic finding diagnostic of Mycoplasma pneumonia infection and PCR-based testing is not routinely used in the clinical setting. Further, the bacteria grows slowly in culture and the diagnostic IgM response will take days after the onset of infection. Thus, a rapid diagnostic test for Mycobacterium pneumonia infection is needed. This study documented two cases of Mycoplasma pneumonia infection of the upper respiratory system using in situ hybridization in a series of over 20 patients who were being tested for SARS-CoV2 infection. The respiratory secretions were placed on a glass slide, fixed in 10 % buffered formalin, and then tested using a Mycoplasma pneumonia probe. The high bacterial number associated with acute infection allowed for straightforward detection by in situ hybridization in a few hours. Antibiotic therapy led to rapid resolution of the symptoms. This highlights the ability of standard in situ hybridization as a rapid diagnostic test for Mycoplasma pneumonia in the clinical setting.

The amplification of CNS damage in Alzheimer's disease due to SARS-CoV2 infection

Pre-existing Alzheimer's disease is a risk factor for severe/fatal COVID-19 and infection by SARS-CoV2 virus has been associated with an increased incidence of un-masked Alzheimer's disease. The molecular basis whereby SARS-CoV2 may amplify Alzheimer's disease is not well understood. This study analyzed the molecular changes in autopsy brain tissues from people with pre-existing dementia who died of COVID-19 (n = 5) which was compared to equivalent tissues of people who died of COVID-19 with no history of dementia (n = 8), Alzheimer's disease pre-COVID-19 (n = 10) and aged matched controls (n = 10) in a blinded fashion. Immunohistochemistry analyses for hyperphosphorylated tau protein, α-synuclein, and β-amyloid-42 confirmed the diagnoses of Alzheimer's disease (n = 4), and Lewy body dementia (n = 1) in the COVID-19 group. The brain tissues from patients who died of COVID-19 with no history of dementia showed a diffuse microangiopathy marked by endocytosis of spike subunit S1 and S2 in primarily CD31+ endothelia with strong co-localization with ACE2, Caspase-3, IL6, TNFα, and Complement component 6 that was not associated with SARS-CoV2 RNA. Microglial activation marked by increased TMEM119 and MCP1 protein expression closely paralleled the endocytosed spike protein. The COVID-19 tissues from people with no pre-existing dementia showed, compared to controls, 5-10× fold increases in expression of neuronal NOS and NMDAR2 as well as a marked decrease in the expression of proteins whose loss is associated with worsening Alzheimer's disease: MFSD2a, SHIP1, BCL6, BCL10, and BACH1. In COVID-19 tissues from people with dementia the widespread spike-induced microencephalitis with the concomitant microglial activation co-existed in the same areas where neurons had hyperphosphorylated tau protein suggesting that the already dysfunctional neurons were additionally stressed by the SARS-CoV2 induced microangiopathy. ACE2+ human brain endothelial cells treated with high dose (but not vaccine equivalent low dose) spike S1 protein demonstrated each of the molecular changes noted in the in vivo COVID-19 and COVID-19/Alzheimer's disease brain tissues. It is concluded that fatal COVID-19 induces a diffuse microencephalitis and microglial activation in the brain due to endocytosis of circulating viral spike protein that amplifies pre-existing dementia in at least two ways: 1) modulates the expression of proteins that may worsen Alzheimer's disease and 2) stresses the already dysfunctional neurons by causing an acute proinflammatory/hypercoagulable/hypoxic microenvironment in areas with abundant hyperphosphorylated tau protein and/or βA-42.

SARS-CoV-2-Induced Pathology-Relevance to COVID-19 Pathophysiology

In spite of intensive studies of different aspects of a new coronavirus infection, many issues still remain unclear. In a screening analysis of histopathology in l200 lethal cases, authors succeeded in performing a wide spectrum of immune histochemical reactions (CD2, CD 3, CD 4, CD 5, CD 7, CD 8, CD14, CD 20, CD 31, CD 34, CD 56, CD 57, CD 68, CD 163, collagen 1,3, spike protein SARS-CoV-2, caspase-3, MLCM; ACE2 receptor, occludin, and claudin-1 and -3) and electron microscopy. The results of the histological and IHC studies of deceased people with varying degrees of severity of coronavirus infection confirmed the ability of these pathogens to cause cytoproliferative changes, primarily in epithelial and endothelial cells. Lesions of various organs are possible, while the reasons for significant differences in organotropy remain unclear. Severe respiratory failure in COVID-19 in humans is associated with a very peculiar viral pneumonia. In the pathogenesis of COVID-19, the most important role is played by lesions of the microcirculatory bed, the genesis of which requires further study, but direct viral damage is most likely. Endothelial damage can be associated with both thrombosis in vessels of various calibers, leading to characteristic complications, and the development of DIC syndrome with maximal kidney damage. Such lesions can be the basis of clinically diagnosed septic shock, while usually there are no morphological data in favor of classical sepsis caused by bacteria or fungi. A massive infiltration of the lung tissue and other organs, mainly by T lymphocytes, including those with suppressor properties, makes it necessary to conduct a differential diagnosis between the morphological manifestation of the protective cellular immune response and direct viral lesions but does not exclude the hypothesis of an immunopathological component of pathogenesis. In many of the deceased, even in the absence of clear clinical symptoms, a variety of extrapulmonary lesions were also detected. The mechanism of their development probably has a complex nature: direct lesions associated with the generalization of viral infection and vascular disorders associated with endothelial damage and having an autoimmune nature. Many aspects of the pathogenesis of coronavirus infection require further comprehensive study.