In Silico Drug Repositioning for COVID-19: Progress and Challenges

he COVID-19 pandemic caused by SARS-CoV-2 has shown a rapid increase in the number of infected patients with a remarkable mortality rate, making it a global public health concern. Because there is currently no specific anti-viral drug for the treatment of COVID-19, repurposing of already approved drugs for other diseases may be explored. Drug repurposing has become a promising approach due to the opportunity to reduce development timelines and overall costs. In this chapter, we will discuss various computational drug repositioning strategies, the current COVID-19 treatment scenario, and challenges to the correct interpretation of existing preclinical/clinical evidence, as well as the generation of new evidence related to drug repurposing. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

Biomimetic lung-on-a-chip to model virus infection and drug evaluation.

Viral infectious diseases remain a global public health problem. The rapid and widespread spread of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV­2) has had a severe impact on the global economy and human activities, highlighting the vulnerability of humans to viral infectious diseases and the urgent need to develop new technologies and effective treatments. Organ-on-a-chip is an emerging technology for constructing the physiological and pathological microenvironment of human organs in vitro and has the advantages of portability, high throughput, low cost, and accurate simulation of the in vivo microenvironment. Indeed, organ-on-a-chip provides a low-cost alternative for investigating human organ physiology, organ diseases, toxicology, and drug efficacy. The lung is a main target organ of viral infection, and lung pathophysiology must be assessed after viral infection and treatment with antiviral drugs. This review introduces the construction of lung-on-a-chip and its related pathophysiological models, focusing on the in vitro simulation of viral infection and evaluation of antiviral drugs, providing a developmental direction for research and treatment of viral diseases.

An Overview on Animal Models to Boost Preclinical Research in COVID 19

The current review was undertaken by collecting data through a thorough literature search in PubMed and Google Scholar in order to identify the relevant English-language articles published on animal models for COVID-19 research. The data was obtained from articles published between 2019 and 2021. After a comprehensive review of various available articles, this review outlines the available animal models for COVID-19 and their key roles in elucidating the pathogenesis, disease transmission, and host response to the SARS-CoV-2 virus. Reports from various preclinical trials have shown the use of several animal models such as mice, hamsters, ferrets, and nonhuman primates (NHPs) for studying the SARS-CoV-2 infection. However, availability of an ideal animal model would help researchers in assessing the efficacy of investigational drugs before they enter clinical trials. No single animal model delineates the totality of pathogenesis or predicts interventional responses faithfully as in humans. Therefore, defining animal models and their use is deemed as a prerequisite for conducting comparative studies of vaccines and therapeutics' efficacy so that the most promising ones advance to the next phase. Copyright © 2022 Wolters Kluwer Medknow Publications. All rights reserved.

Generation of Angiotensin-Converting Enzyme 2/Transmembrane Protease Serine 2-Double-Positive Human Induced Pluripotent Stem Cell-Derived Spheroids for Anti-Severe Acute Respiratory Syndrome Coronavirus 2 Drug Evaluation.

We newly generated two human induced pluripotent stem cell (hiPSC)-derived spheroid lines, termed Spheroids_4MACE2-TMPRSS2 and Spheroids_15M63ACE2-TMPRSS2, both of which express angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2), which are critical for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Both spheroids were highly susceptible to SARS-CoV-2 infection, and two representative anti-SARS-CoV-2 agents, remdesivir and 5h (an inhibitor of SARS-CoV-2's main protease), inhibited the infectivity and replication of SARS-CoV-2 in a dose-dependent manner, suggesting that these human-derived induced spheroids should serve as valuable target cells for the evaluation of anti-SARS-CoV-2 activity. IMPORTANCE The hiPSC-derived spheroids we generated are more expensive to obtain than the human cell lines currently available for anti-SARS-CoV-2 drug evaluation, such as Calu-3 cells; however, the spheroids have better infection susceptibility than the existing human cell lines. Although we are cognizant that there are human lung (and colonic) organoid models for the study of SARS-CoV-2, the production of those organoids is greatly more costly and time consuming than the generation of human iPSC-derived spheroid cells. Thus, the addition of human iPSC-derived spheroids for anti-SARS-CoV-2 drug evaluation studies could provide the opportunity for more comprehensive interpretation of the antiviral activity of compounds against SARS-CoV-2.

Unraveling the mystery of efficacy in Chinese medicine formula: New approaches and technologies for research on pharmacodynamic substances.

Traditional Chinese medicine (TCM) is the key to unlock treasures of Chinese civilization. TCM and its compound play a beneficial role in medical activities to cure diseases, especially in major public health events such as novel coronavirus epidemics across the globe. The chemical composition in Chinese medicine formula is complex and diverse, but their effective substances resemble "mystery boxes". Revealing their active ingredients and their mechanisms of action has become focal point and difficulty of research for herbalists. Although the existing research methods are numerous and constantly updated iteratively, there is remain a lack of prospective reviews. Hence, this paper provides a comprehensive account of existing new approaches and technologies based on previous studies with an in vitro to in vivo perspective. In addition, the bottlenecks of studies on Chinese medicine formula effective substances are also revealed. Especially, we look ahead to new perspectives, technologies and applications for its future development. This work reviews based on new perspectives to open horizons for the future research. Consequently, herbal compounding pharmaceutical substances study should carry on the essence of TCM while pursuing innovations in the field.

Efficacy of early use of remdesivir: a systematic review of subgroup analysis.

OBJECTIVE: A possible benefit has been suggested for early treatment of severe coronavirus disease 2019 (COVID-19) with remdesivir. The efficacy of this drug is controversial and could significantly influence the efficiency in healthcare systems. The objective is the methodological interpretation of subgroup analyzes according to starting of remdesivir treatment with respect to symptom onset of COVID-19. METHODS: A search in Pubmed® database was performed. Randomized clinical trials (RCTs) with subgroup analysis regarding early and late use of remdesivir were selected. All endpoints were assessed using two methodologies. First methodology considered statistical interaction, pre-specification, biological plausibility, and consistency of results. Second methodology was a validated tool with preliminary questions to discard subset analysis without relevant minimum conditions, and a checklist with recommendations for applicability. RESULTS: A total of 54 results were found and five RCTs were selected. According first methodology, consistent heterogeneity was only found in time to clinical improvement and better clinical status score at day 15 for patients with severe COVID-19 and <7 days of symptoms. About second methodology, these results about early use of remdesivir may be applied to clinical practice with caution. CONCLUSIONS: We developed a systematic search and application of an established methodology for interpretation of subgroup analysis about early use of remdesivir. Results in severe COVID-19 suggested that early use of remdesivir provides a greater benefit in <7 days of symptoms for time to clinical improvement and better clinical status score at day 15. Future studies could use 7-day cut-off of symptoms to evaluate remdesivir.

An Immuno-Cardiac Model for Macrophage-Mediated Inflammation in COVID-19 Hearts.

[Figure: see text].

Construction of Non-infectious SARS-CoV-2 Replicons and Their Application in Drug Evaluation.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a devastating pandemic worldwide. Vaccines and antiviral drugs are the most promising candidates for combating this global epidemic, and scientists all over the world have made great efforts to this end. However, manipulation of the SARS-CoV-2 should be performed in the biosafety level 3 laboratory. This makes experiments complicated and time-consuming. Therefore, a safer system for working with this virus is urgently needed. Here, we report the construction of plasmid-based, non-infectious SARS-CoV-2 replicons with turbo-green fluorescent protein and/or firefly luciferase reporters by reverse genetics using transformation-associated recombination cloning in Saccharomyces cerevisiae. Replication of these replicons was achieved simply by direct transfection of cells with the replicon plasmids as evident by the expression of reporter genes. Using SARS-CoV-2 replicons, the inhibitory effects of E64-D and remdesivir on SARS-CoV-2 replication were confirmed, and the half-maximal effective concentration (EC50) value of remdesivir and E64-D was estimated by different quantification methods respectively, indicating that these SARS-CoV-2 replicons are useful tools for antiviral drug evaluation.