Imaging Diagnostics and Pathology in SARS-CoV-2-Related Diseases

[99Tc]Sestamibi bioaccumulation induces apoptosis in prostate cancer cells: an in vitro study

The main aim of this preliminary in vitro study was to evaluate both the uptake of [⁹⁹Tc]Sestamibi into prostate cancer cells and the relationship among [⁹⁹Tc]Sestamibi bioaccumulation, cancer cells proliferation and apoptosis. An in vitro study in which PC3 prostate cancer cell line was cultured with increasing doses of decayed sestamibi has been developed. Specifically, PC3 cells were incubated with three different concentrations of [⁹⁹Tc]Sestamibi: 10 µg/mL, 1 µg/mL, and 0.1 µg/mL Expression of apoptotic caspase-3 and AIF, as well as the ultrastructure of PC3 cells, were evaluated at T0 and after 24, 48, 72, and 120 h following [⁹⁹Tc]Sestamibi incubation. Data here reported showed the bioaccumulation of sestamibi in prostate cancer cells. As concern the cancer cell homeostasis, the treatment of PC3 cells with [⁹⁹Tc]Sestamibi strongly influenced the cells proliferation. Indeed, a significant reduction in the number of mitosis was observed. Noteworthy, the accumulation of sestamibi in prostate cancer cells was associated with the appearance of morphological signs of apoptosis. The increase in AIF and caspase 3 expression in prostate cancer cells treated with 10 µg/mL of [⁹⁹Tc]Sestamibi confirmed that this radiopharmaceutical can trigger the apoptosis. To the best of our knowledge, this preliminary study reported for the first time in vitro data about the uptake of sestamibi in prostate cancer cells. The evidence about the accumulation of sestamibi in prostate cancer cells and its role in the apoptosis process could open new clinical perspectives on the use of this radiopharmaceutical in both the diagnosis and treatment of prostate cancers.

Theoretical Investigation of the Coronavirus SARS-CoV-2 (COVID-19) Infection Mechanism and Selectivity

The SARS-CoV-2 virus, commonly known as COVID-19, first occurred in December 2019 in Wuhan, Hubei Province, China. Since then, it has become a tremendous threat to human health. With a pandemic threat, it is in the significant interest of the scientific world to establish its method of infection. In this manuscript, we combine knowledge of the infection mechanism with theoretical methods to answer the question of the virus’s selectivity. We proposed a two-stage infection mechanism. In the first step, the virus interacts with the ACE2 receptor, with the “proper strength”. When the interaction is too strong, the virus will remain in an “improper position”; if the interaction is too weak, the virus will “run away” from the cell. We also indicated three residues (positions 30, 31, and 353) located on the ACE2 protein-binding interface, which seems to be crucial for successful infection. Our results indicate that these residues are necessary for the initiation of the infection process.

Radiopharmaceutical preclinical investigation: an accurate and multidisciplinary approach

BACKGROUND

The development of less expensive and pivotal methodologies, capable to support the researchers in the radiopharmaceutical pre-clinical investigations could provide a crucial incentive for developing biomedical research involved in the realization of tailored target therapies.

OBJECTIVE

The aim of this pilot study was to evaluate the capability of a digital autoradiography system equipped with a laser scanning device to perform [18F]choline biodistribution evaluation in a xenograft mouse model of prostate cancer.

METHODS

PC3 prostate cancer cells were used to develop xenografts in NOD/SCID mice. The biodistribution of the radiopharmaceutical was evaluated at 30,60 and 120 min after injection in excised organs by using a digital autoradiography system equipped with super resolution laser screen. Histological and immunohistochemical analysis were performed to correlate the [18F]choline uptake with morphological and molecular tumours characteristics.

RESULTS

Data here reported clearly indicate the possibility to perform accurate biodistribution studies by using the digital autoradiographic system equipped with a super resolution screen. Specifically, a significant increase in the [18F]choline inhibitor uptake in PC3 tumours as compared to heart, bowel, liver and kidney at both 30 and 60 min was observed. More important, the digital autoradiographic system showed signal uptake almost exclusively in the PC3 tumors at 60 min post-injection. Noteworthy, immunohistochemical analysis demonstrated a strong overlapping between the [18F]choline uptake and the proliferation index (Ki67 expression).

CONCLUSIONS

The use of autoradiography system in pre-clinical investigations could shed new light on the molecular mechanisms that orchestrate the tissues damage induced by therapeutical radiopharmaceuticals.

Early CT features of COVID-19 pneumonia, association with patients’ age and duration of presenting complaint

Background

Coronavirus disease (COVID-19) is a respiratory syndrome with a variable degree of severity. Imaging is a vital component of disease monitoring and follow-up in coronavirus pulmonary syndromes. The study of temporal changes of CT findings of COVID-19 pneumonia can help in better understanding of disease pathogenesis and prediction of disease prognosis. In this study, we aim to determine the typical and atypical CT imaging features of COVID-19 and discuss the association of typical CT imaging features with the duration of the presenting complaint and patients’ age.

Results

The lesions showed unilateral distribution in 20% of cases and bilateral distribution in 80% of cases. The lesions involved the lower lung lobes in 30% of cases and showed diffuse involvement in 58.2% of cases. The lesions showed peripheral distribution in 74.5% of cases. The most common pattern was multifocal ground glass opacity found in 72.7% of cases. Atypical features like cavitation and pleural effusion can occur early in the disease course. There was significant association between increased number of the lesions, bilaterality, diffuse pattern of lung involvement and older age group (≥ 50 years old) and increased duration of presenting complaint (≥ 4 days). There was significant association between crazy-paving pattern and increased duration of presenting complaint. No significant association could be detected between any CT pattern and increased patient age.

Conclusion

The most common CT feature of COVID-19 was multifocal ground glass opacity. Atypical features like cavitation and pleural effusion can occur early in the course of the disease. Our cases showed more extensive lesions with bilateral and diffuse patterns of distribution in the older age group and with increased duration of presenting complaint. There was a significant association between crazy-paving pattern and increased duration of presenting complaint. No significant association could be detected between any CT pattern and increased patient age.

Positron emission tomography in the COVID-19 pandemic era

Coronavirus disease 2019 (COVID-19) has become a major public health problem worldwide since its outbreak in 2019. Currently, the spread of COVID-19 is far from over, and various complications have roused increasing awareness of the public, calling for novel techniques to aid at diagnosis and treatment. Based on the principle of molecular imaging, positron emission tomography (PET) is expected to offer pathophysiological alternations of COVID-19 in the molecular/cellular perspectives and facilitate the clinical management of patients. A number of PET-related cases and research have been reported on COVID-19 over the past one year. This article reviews the current studies of PET in the diagnosis and treatment of COVID-19, and discusses potential applications of PET in the development of management strategy for COVID-19 patients in the pandemic era.

Emerging and Established Histological Techniques for the Analysis of Thrombosis in COVID-19 Lungs

Coronavirus disease 2019 (COVID-19) is the potentially lethal disease that is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients with COVID-19 have an increased risk of thrombosis, but the role of thrombosis in the pathogenesis and progression of severe COVID-19 remains unclear. A better understanding of the contribution of thrombosis to the development and progression of COVID-19 could lead to the development of novel COVID-19 treatments. For this reason, established and emerging histological techniques have recently been used to analyze COVID-19 lungs quantitatively and visually and in two and three dimensions. The gold standard and novel state-of the-art histological techniques that have been used to assess thrombosis in COVID-19 lungs are described in this Mini Review.

Potential antiviral activity of isorhamnetin against SARS-CoV-2 spike pseudotyped virus in vitro

Coronavirus Disease 2019 (COVID-19) cases and deaths are still rising worldwide, there is currently no effective treatment for severe inflammation and acute lung injury caused by new coronavirus (SARS-COV-2) infection. Therapies to prevent or treat COVID-19, including antiviral drug and several vaccines, are still being development. Human angiotensin-converting enzyme 2 (ACE2), expressing in lung, has been confirmed to be a receptor for SARS-COV-2 infection, interventions for attachment of spike protein of SARS-CoV-2 to ACE2 may be a potential approach to prevent viral infections and it is considered as a potential target for drug development. In this study, we observed that seabuckthorn and its flavonoid compounds quercetin and isorhamnetin were shown strong retention to ACE2 overexpression HEK293 (ACE2^h ) cells by CMC analysis. Based on drug receptor interaction analysis and viral entry studies in vitro, we evaluated the interaction of two flavonoid compounds and ACE2 as well as the inhibitory effect of the two compounds on viral entry. Surface plasmon resonance assay proved the effect that isorhamnetin bound to the ACE2, and its affinity (KD value) was at the micromolar level, that was, 2.51 ± 0.68 μM. Viral entry studies in vitro indicated that isorhamnetin inhibited SARS-CoV-2 spike pseudotyped virus entering ACE2^h cells. Based on promising in vitro results, we proposed isorhamnetin to be a potential therapeutic candidate compound against COVID-19.

Persistence of SARS-CoV-2 Viral RNA in Nasopharyngeal Swabs after Death: An Observational Study

The aim of this study was to investigate the persistence of SARS-CoV-2 in post-mortem swabs of subjects who died from SARS-CoV-2 infection. The presence of the virus was evaluated post-mortem from airways of 27 SARS-CoV-2 positive patients at three different time points (T1 2 h; T2 12 h; T3 24 h) by real-time PCR. Detection of antibodies to SARS-CoV-2 was performed by Maglumi 2019-nCoV IgM/IgG chemiluminescence assay. SARS-CoV-2 viral RNA was still detectable in 70.3% of cases within 2 h after death and in 66,6% of cases up to 24 h after death. Our data showed an increase of the viral load in 78,6% of positive individuals 24 h post-mortem (T3) in comparison to that evaluated 2 h after death (T1). Noteworthy, we detected a positive T3 post-mortem swab (24 h after death) from 4 subjects who were negative at T1 (2 h after death). The results of our study may have an important value in the management of deceased subjects not only with a suspected or confirmed diagnosis of SARS-CoV-2, but also for unspecified causes and in the absence of clinical documentation or medical assistance.

The Rationale for Angiotensin Receptor Neprilysin Inhibitors in a Multi-Targeted Therapeutic Approach to COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) determines the angiotensin converting enzyme 2 (ACE2) down-regulation and related decrease in angiotensin II degradation. Both these events trigger “cytokine storm” leading to acute lung and cardiovascular injury. A selective therapy for COVID-19 has not yet been identified. Clinical trials with remdesivir gave discordant results. Thus, healthcare systems have focused on “multi-targeted” therapeutic strategies aiming at relieving systemic inflammation and thrombotic complications. No randomized clinical trial has demonstrated the efficacy of renin angiotensin system antagonists in reducing inflammation related to COVID-19. Dexamethasone and tocilizumab showed encouraging data, but their use needs to be further validated. The still-controversial efficacy of these treatments highlighted the importance of organ injury prevention in COVID-19. Neprilysin (NEP) might be an interesting target for this purpose. NEP expression is increased by cytokines on lung fibroblasts surface. NEP activity is elevated in acute respiratory distress syndrome and it is conceivable that it is also high in COVID-19. NEP is implicated in the degradation of natriuretic peptides, bradykinin, substance P, adrenomedullin, and apelin that account for prevention of organ injury. Thus, NEP/angiotensin receptor type 1 (AT1R) inhibitor sacubitril/valsartan (SAC/VAL) may increase levels of these molecules and block AT1Rs required for ACE2 endocytosis in SARS-CoV-2 infection. Moreover, SAC/VAL has a positive impact on acute heart failure that is very frequently observed in deceased COVID-19 patients. The current review aims to summarize actual therapeutic strategies for COVID-19 and to examine the data supporting the potential benefits of SAC/VAL in COVID-19 treatment.