Homo-harringtonine, highly effective against coronaviruses, is safe in treating COVID-19 by nebulization

In vitro pharmacokinetic behavior in lung of harringtonine, an antagonist of SARS-CoV-2 associated proteins: New insights of inhalation therapy for COVID-19

BACKGROUND

Recent studies have shown that harringtonine (HT) could specifically bind with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein and host cell transmembrane serine protease 2 (TMPRSS2) to block membrane fusion, which is an effective antagonist for SARS-CoV-2.

PURPOSE

Our study focused on in-depth exploration of in vitro pharmacokinetic characteristics of HT in lung.

METHODS

HPLC-fluorescence detection method was used to detect changes of HT content. Incubation systems of lung microsomes for phase I metabolism and UGT incubation systems for phase II metabolism were performed to elucidate metabolites and metabolic mechanisms of HT, and then the metabolic enzyme phenotypes for HT were clarified by chemical inhibition method and recombinant enzyme method. Through metabolomics, we comprehensively evaluated the physiological dynamic changes in SD rat and human lung microsomes, and revealed the relationship between metabolomics and pharmacological activity of HT.

RESULTS

HPLC-fluorescence detection method showed strong specificity, high accuracy, and good stability for rapid quantification of HT. We confirmed that HT mainly underwent phase I metabolism, and the metabolites of HT in different species were all identified as 4'-demethyl HT, with metabolic pathway being hydrolysis reaction. CYP1A2 and CYP2E1 participated in HT metabolism, but as HT metabolism was not NADPH dependent, the esterase HCES1 in lung also played a role. The main KEGG pathways in SD rat and human lung microsomes were cortisol synthesis and secretion, steroid hormone biosynthesis and linoleic acid metabolism, respectively. The downregulated key biomarkers of 11-deoxycortisol, 21-deoxycortisol and 9(10)-EpOME suggested that HT could prevent immunosuppression and interfere with infection and replication of SARS-CoV-2.

CONCLUSION

HT was mainly metabolized into 4'-demethyl HT through phase I reactions, which was mediated by CYP1A2, CYP2E1, and HCES1. The downregulation of 11-deoxycortisol, 21-deoxycortisol and 9(10)-EpOME were key ways of HT against SARS-CoV-2. Our study was of great significance for development and clinical application of HT in the treatment of COVID-19.

Homoharringtonine promotes heart allograft acceptance by enhancing regulatory T cells induction in a mouse model

BACKGROUND

Homoharringtonine (HHT) is an effective anti-inflammatory, anti-viral, and anti-tumor protein synthesis inhibitor that has been applied clinically. Here, we explored the therapeutic effects of HHT in a mouse heart transplant model.

METHODS

Healthy C57BL/6 mice were used to observe the toxicity of HHT in the liver, kidney, and hematology. A mouse heart transplantation model was constructed, and the potential mechanism of HHT prolonging allograft survival was evaluated using Kaplan-Meier analysis, immunostaining, and bulk RNA sequencing analysis. The HHT-T cell crosstalk was modeled ex vivo to further verify the molecular mechanism of HHT-induced regulatory T cells (Tregs) differentiation.

RESULTS

HHT inhibited the activation and proliferation of T cells and promoted their apoptosis ex vivo . Treatment of 0.5 mg/kg HHT for 10 days significantly prolonged the mean graft survival time of the allografts from 7 days to 48 days ( P <0.001) without non-immune toxicity. The allografts had long-term survival after continuous HHT treatment for 28 days. HHT significantly reduced lymphocyte infiltration in the graft, and interferon-γ-secreting CD4 + and CD8 + T cells in the spleen ( P <0.01). HHT significantly increased the number of peripheral Tregs (about 20%, P <0.001) and serum interleukin (IL)-10 levels. HHT downregulated the expression of T cell receptor (TCR) signaling pathway-related genes ( CD4 , H2-Eb1 , TRAT1 , and CD74 ) and upregulated the expression of IL-10 and transforming growth factor (TGF)-β pathway-related genes and Treg signature genes ( CTLA4 , Foxp3 , CD74 , and ICOS ). HHT increased CD4 + Foxp3 + cells and Foxp3 expression ex vivo , and it enhanced the inhibitory function of inducible Tregs.

CONCLUSIONS

HHT promotes Treg cell differentiation and enhances Treg suppressive function by attenuating the TCR signaling pathway and upregulating the expression of Treg signature genes and IL-10 levels, thereby promoting mouse heart allograft acceptance. These findings may have therapeutic implications for organ transplant recipients, particularly those with viral infections and malignancies, which require a more suitable anti-rejection medication.

Homoharringtonine: updated insights into its efficacy in hematological malignancies, diverse cancers and other biomedical applications

HHT has emerged as a notable compound in the realm of cancer treatment, particularly for hematological malignancies. Its multifaceted pharmacological properties extend beyond traditional applications, warranting an extensive review of its mechanisms and efficacy. This review aims to synthesize comprehensive insights into the efficacy of HHT in treating hematological malignancies, diverse cancers, and other biomedical applications. It focuses on elucidating the molecular mechanisms, therapeutic potential, and broader applications of HHT. A comprehensive search for peer-reviewed papers was conducted across various academic databases, including ScienceDirect, Web of Science, Scopus, American Chemical Society, Google Scholar, PubMed/MedLine, and Wiley. The review highlights HHT's diverse mechanisms of action, ranging from its role in leukemia treatment to its emerging applications in managing other cancers and various biomedical conditions. It underscores HHT's influence on cellular processes, its efficacy in clinical settings, and its potential to alter pathological pathways. HHT demonstrates significant promise in treating various hematological malignancies and cancers, offering a multifaceted approach to disease management. Its ability to impact various physiological pathways opens new avenues for therapeutic applications. This review provides a consolidated foundation for future research and clinical applications of HHT in diverse medical fields.

Molecular insights into the inhibition mechanism of harringtonine against essential proteins associated with SARS-CoV-2 entry

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has recently posed a serious threat to global public health. Harringtonine (HT), as a small-molecule antagonist, has antiviral activity against a variety of viruses. There is evidence that HT can inhibit the SARS-CoV-2 entry into host cells by blocking the Spike protein and transmembrane protease serine 2 (TMPRSS2). However, the molecular mechanism underlying the inhibition effect of HT is largely elusive. Here, docking and all-atom molecular dynamic simulations were used to investigate the mechanism of HT against the receptor binding domain (RBD) of Spike, TMPRSS2, as well as the complex of RBD and angiotensin-converting enzyme 2 complex (RBD-ACE2). The results reveal that HT binds to all proteins primarily through hydrogen bond and hydrophobic interactions. Binding with HT influences the structural stability and dynamic motility processes of each protein. The interactions of HT with residues N33, H34 and K353 of ACE2, and residue K417 and Y453 of RBD contribute to disrupting the binding affinity between RBD and ACE2, which may hinder the virus entry into host cells. Our research provides molecular insights into the inhibition mechanism of HT against SARS-CoV-2 associated proteins, which will help for the novel antiviral drugs development.

Elucidating host cell response pathways and repurposing therapeutics for SARS-CoV-2 and other coronaviruses

COVID-19, first reported in late 2019, is an ongoing pandemic that has been causing devastation across the globe. Although there are multiple vaccines that can prevent severe symptoms, effective COVID-19 therapeutics are still of importance. Using our proprietary in silico engine, we screened more than 22,000 unique compounds represented by over half a million gene expression profiles to uncover compounds that can be repurposed for SARS-CoV-2 and other coronaviruses in a timely and cost-efficient manner. We then tested 13 compounds in vitro and found three with potency against SARS-CoV-2 with reasonable cytotoxicity. Bortezomib and homoharringtonine are some of the most promising hits with IC₅₀ of 1.39 μM and 0.16 μM, respectively for SARS-CoV-2. Tanespimycin and homoharringtonine were effective against the common cold coronaviruses. In-depth analysis highlighted proteasome, ribosome, and heat shock pathways as key targets in modulating host responses during viral infection. Further studies of these pathways and compounds have provided novel and impactful insights into SARS-CoV-2 biology and host responses that could be further leveraged for COVID-19 therapeutics development.

Overview of Antiviral Drug Therapy for COVID-19: Where Do We Stand?

The vaccine weapon has resulted in being essential in fighting the COVID-19 outbreak, but it is not fully preventing infection due to an alarming spreading of several identified variants of concern. In fact, the recent emergence of variants has pointed out how the SARS-CoV-2 pandemic still represents a global health threat. Moreover, oral antivirals also develop resistance, supporting the need to find new targets as therapeutic tools. However, cocktail therapy is useful to reduce drug resistance and maximize vaccination efficacy. Natural products and metal-drug-based treatments have also shown interesting antiviral activity, representing a valid contribution to counter COVID-19 outbreak. This report summarizes the available evidence which supports the use of approved drugs and further focuses on significant clinical trials that have investigated the safety and efficacy of repurposing drugs and new molecules in different COVID-19 phenotypes. To date, there are many individuals vulnerable to COVID-19 exhibiting severe symptoms, thus characterizing valid therapeutic strategies for better management of the disease is still a challenge.