Phenothiazines inhibit SARS-CoV-2 cell entry via a blockade of spike protein binding to neuropilin-1

The histamine receptor H1 acts as an alternative receptor for SARS-CoV-2

Numerous host factors, in addition to human angiotensin-converting enzyme 2 (hACE2), have been identified as coreceptors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), demonstrating broad viral tropism and diversified druggable potential. We and others have found that antihistamine drugs, particularly histamine receptor H1 (HRH1) antagonists, potently inhibit SARS-CoV-2 infection. In this study, we provided compelling evidence that HRH1 acts as an alternative receptor for SARS-CoV-2 by directly binding to the viral spike protein. HRH1 also synergistically enhanced hACE2-dependent viral entry by interacting with hACE2. Antihistamine drugs effectively prevent viral infection by competitively binding to HRH1, thereby disrupting the interaction between the spike protein and its receptor. Multiple inhibition assays revealed that antihistamine drugs broadly inhibited the infection of various SARS-CoV-2 mutants with an average IC50 of 2.4 µM. The prophylactic function of these drugs was further confirmed by authentic SARS-CoV-2 infection assays and humanized mouse challenge experiments, demonstrating the therapeutic potential of antihistamine drugs for combating coronavirus disease 19.IMPORTANCEIn addition to human angiotensin-converting enzyme 2, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can utilize alternative cofactors to facilitate viral entry. In this study, we discovered that histamine receptor H1 (HRH1) not only functions as an independent receptor for SARS-CoV-2 but also synergistically enhances ACE2-dependent viral entry by directly interacting with ACE2. Further studies have demonstrated that HRH1 facilitates the entry of SARS-CoV-2 by directly binding to the N-terminal domain of the spike protein. Conversely, antihistamine drugs, primarily HRH1 antagonists, can competitively bind to HRH1 and thereby prevent viral entry. These findings revealed that the administration of repurposable antihistamine drugs could be a therapeutic intervention to combat coronavirus disease 19.

Basic implications on three pathways associated with SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) interacts between the host and virus and govern induction, resulting in multiorgan impacts. Its pathophysiology involves the followings: 1) the angiotensin-converting enzyme (ACE2) and Toll-like receptor (TLR) pathways: 2) the neuropilin (NRP) pathway: 3) the spike protein pathway. Therefore, it is necessary to block the pathological course with modulating innate lymphoid cells against diverse corona variants in the future.

Comprehensive analysis and immunohistochemistry localization of NRP1 expression in pancancer and normal individual tissues in relation to SARS‑CoV‑2 susceptibility

Neuropilin 1 (NRP1/CD304) is a typical membrane-bound co-receptor for vascular endothelial growth factor, semaphorin family members and viral severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, NRP1 expression levels across cancer types and the potential role of SARS-CoV-2 infection in patients with cancer are not clear. Online databases, such as The Cancer Genome Atlas database of Human Protein Atlas, Gene Expression Profiling Interactive Analysis and cBioPortal were used for the expression analysis in this study. Immunohistochemical (IHC) staining for NRP1 was performed in the tissues of patients with non-small cell carcinoma. As a result, it was found that NRP1 mRNA and protein expression levels were highest in the female reproductive tissues and the respiratory system, specifically in the nasopharynx, bronchus and fallopian tube, as well as in adipocytes, hepatic stellate cells, Sertoli cells, endothelial cells and dendritic cells. IHC showed that the NRP1 protein was mainly localized to the cytoplasm and membrane in the tissues of patients with non-small cell carcinoma, demonstrating its role in lung infection by SARS-CoV-2, due to invasion of cell membranes by the virus. Levels of NRP1 mRNA were significantly increased in lymphoid neoplasm diffuse large B-cell lymphoma, esophageal carcinoma, glioblastoma multiforme, head and neck squamous cell carcinoma, kidney renal clear cell carcinoma (KIRC), pancreatic adenocarcinoma, stomach adenocarcinoma and thymoma, and significantly decreased in cervical squamous cell carcinoma and endocervical adenocarcinoma, kidney chromophobe, lung squamous cell carcinoma, ovarian serous cystadenocarcinoma, uterine corpus endometrial carcinoma and uterine carcinosarcoma, compared with corresponding healthy tissues in pancancer, indicating roles for viral invasion in most cancer types. Moreover, low NRP1 expression was significantly associated with long overall survival (OS) time in adrenocortical carcinoma, brain lower grade glioma, stomach adenocarcinoma and uveal melanoma, but with short OS time in KIRC only. The ENST00000374867.6 (NRP1-202) isoform is most highly expressed in most cancer types and thus could be involved in tumorigenesis and SARS-CoV-2 invasion in cancer patients. NRP1 may be involved in SARS-CoV-2 invasion in patients with cancer, including those with lung cancer.

Targeting SARS-CoV-2 entry processes: The promising potential and future of host-targeted small-molecule inhibitors

The COVID-19 pandemic, caused by SARS-CoV-2, has had a huge impact on global health. To respond to rapidly mutating viruses and to prepare for the next pandemic, there is an urgent need to develop small molecule therapies that target critical stages of the SARS-CoV-2 life cycle. Inhibiting the entry process of the virus can effectively control viral infection and play a role in prevention and treatment. Host factors involved in this process, such as ACE2, TMPRSS2, ADAM17, furin, PIKfyve, TPC2, CTSL, AAK1, V-ATPase, HSPG, and NRP1, have been found to be potentially good targets with stability. Through further exploration of the cell entry process of SARS-CoV-2, small-molecule drugs targeting these host factors have been developed. This review focuses on the structural functions of potential host cell targets during the entry of SARS-CoV-2 into host cells. The research progress, chemical structure, structure-activity relationship, and clinical value of small-molecule inhibitors against COVID-19 are reviewed to provide a reference for the development of small-molecule drugs against COVID-19.

Methotrimeprazine is a neuroprotective antiviral in JEV infection via adaptive ER stress and autophagy

Japanese encephalitis virus (JEV) pathogenesis is driven by a combination of neuronal death and neuroinflammation. We tested 42 FDA-approved drugs that were shown to induce autophagy for antiviral effects. Four drugs were tested in the JE mouse model based on in vitro protective effects on neuronal cell death, inhibition of viral replication, and anti-inflammatory effects. The antipsychotic phenothiazines Methotrimeprazine (MTP) & Trifluoperazine showed a significant survival benefit with reduced virus titers in the brain, prevention of BBB breach, and inhibition of neuroinflammation. Both drugs were potent mTOR-independent autophagy flux inducers. MTP inhibited SERCA channel functioning, and induced an adaptive ER stress response in diverse cell types. Pharmacological rescue of ER stress blocked autophagy and antiviral effect. MTP did not alter translation of viral RNA, but exerted autophagy-dependent antiviral effect by inhibiting JEV replication complexes. Drug-induced autophagy resulted in reduced NLRP3 protein levels, and attenuation of inflammatory cytokine/chemokine release from infected microglial cells. Our study suggests that MTP exerts a combined antiviral and anti-inflammatory effect in JEV infection, and has therapeutic potential for JE treatment.

Natural Product Cordycepin (CD) Inhibition for NRP1/CD304 Expression and Possibly SARS-CoV-2 Susceptibility Prevention on Cancers

NRP1/CD304 is a typical membrane-bound co-receptor for the vascular endothelial cell growth factor (VEGF), semaphorin family members, and viral SARS-CoV-2. Cordycepin (CD) is a natural product or active gradient from traditional Chinese medicine (TCM) from Cordyceps militaris Link and Ophiocordyceps sinensis (Berk.). However, NRP1 expression regulation via CD in cancers and the potential roles and mechanisms of SARS-CoV-2 infection are not clear. In this study, online databases were analyzed, Western blotting and quantitative RT-PCR were used for NRP1 expression change via CD, molecular docking was used for NRP/CD interaction, and a syncytial formation assay was used for CD inhibition using a pseudovirus SARS-CoV-2 entry. As a result, we revealed that CD inhibits NRP1 expressed in cancer cells and prevents viral syncytial formation in 293T-hACE2 cells, implying the therapeutic potential for both anti-cancer and anti-viruses, including anti-SARS-CoV-2. We further found significant associations between NRP1 expressions and the tumor-immune response in immune lymphocytes, chemokines, receptors, immunostimulators, immune inhibitors, and major histocompatibility complexes in most cancer types, implying NRP1's roles in both anti-cancer and anti-SARS-CoV-2 entry likely via immunotherapy. Importantly, CD also downregulated the expression of NRP1 from lymphocytes in mice and downregulated the expression of A2AR from the lung cancer cell line H1975 when treated with CD, implying the NRP1 mechanism probably through immuno-response pathways. Thus, CD may be a therapeutic component for anti-cancer and anti-viral diseases, including COVID-19, by targeting NRP1 at least.

The development and application of pseudoviruses: assessment of SARS-CoV-2 pseudoviruses

Although most Coronavirus disease (COVID-19) patients can recover fully, the disease remains a significant cause of morbidity and mortality. In addition to the consequences of acute infection, a proportion of the population experiences long-term adverse effects associated with SARS-CoV-2. Therefore, it is still critical to comprehend the virus's characteristics and how it interacts with its host to develop effective drugs and vaccines against COVID-19. SARS-CoV-2 pseudovirus, a replication-deficient recombinant glycoprotein chimeric viral particle, enables investigations of highly pathogenic viruses to be conducted without the constraint of high-level biosafety facilities, considerably advancing virology and being extensively employed in the study of SARS-CoV-2. This review summarizes three methods of establishing SARS-CoV-2 pseudovirus and current knowledge in vaccine development, neutralizing antibody research, and antiviral drug screening, as well as recent progress in virus entry mechanism and susceptible cell screening. We also discuss the potential advantages and disadvantages.

A phenothiazine urea derivative broadly inhibits coronavirus replication via viral protease inhibition

Coronavirus (CoV) replication requires efficient cleavage of viral polyproteins into an array of non-structural proteins involved in viral replication, organelle formation, viral RNA synthesis, and host shutoff. Human CoVs (HCoVs) encode two viral cysteine proteases, main protease (Mpro) and papain-like protease (PLpro), that mediate polyprotein cleavage. Using a structure-guided approach, a phenothiazine urea derivative that inhibits both SARS-CoV-2 Mpro and PLpro protease activity was identified. In silico docking studies also predicted the binding of the phenothiazine urea to the active sites of structurally similar Mpro and PLpro proteases from distantly related alphacoronavirus, HCoV-229 E (229 E), and the betacoronavirus, HCoV-OC43 (OC43). The lead phenothiazine urea derivative displayed broad antiviral activity against all three HCoVs tested in cellulo. It was further demonstrated that the compound inhibited 229 E and OC43 at an early stage of viral replication, with diminished formation of viral replication organelles, and the RNAs that are made within them, as expected following viral protease inhibition. These observations suggest that the phenothiazine urea derivative readily inhibits viral replication and may broadly inhibit proteases of diverse coronaviruses.

Discovery of novel phenothiazine derivatives as new agrochemical alternatives for treating plant viral diseases

BACKGROUND

Plant viral diseases, namely 'plant cancer', are extremely difficult to control. Even worse, few antiviral agents can effectively control and totally block viral infection. There is an urgent need to explore and discover novel agrochemicals with high activity and a unique mode of action to manage these refractory diseases.

RESULTS

Forty-one new phenothiazine derivatives were prepared and their inhibitory activity against tobacco mosaic virus (TMV) was assessed. Compound A8 had the highest protective activity against TMV, with a half-maximal effective concentration (EC50 ) of 115.67 μg/mL, which was significantly better than that of the positive controls ningnanmycin (271.28 μg/mL) and ribavirin (557.47 μg/mL). Biochemical assays demonstrated that compound A8 could inhibit TMV replication by disrupting TMV self-assembly, but also enabled the tobacco plant to enhance its defense potency by increasing the activities of various defense enzymes.

CONCLUSION

In this study, novel phenothiazine derivatives were elaborately fabricated and showed remarkable anti-TMV behavior that possessed the dual-action mechanisms of inhibiting TMV assembly and invoking the defense responses of tobacco plants. Moreover, new agrochemical alternatives based on phenothiazine were assessed for their antiviral activities and showed extended agricultural application. © 2023 Society of Chemical Industry.

Is neuropilin-1 the neuroimmune initiator of multi-system hyperinflammation in COVID-19?

A major immunopathological feature of Coronavirus disease-2019 (COVID-19) is excessive inflammation in the form of "cytokine storm". The storm is characterized by injurious levels of cytokines which form a complicated network damaging different organs, including the lungs and the brain. The main starter of "cytokine network" hyperactivation in COVID-19 has not been discovered yet. Neuropilins (NRPs) are transmembrane proteins that act as neuronal guidance and angiogenesis modulators. The crucial function of NRPs in forming the nervous and vascular systems has been well-studied. NRP1 and NRP2 are the two identified homologs of NRP. NRP1 has been shown as a viral entry pathway for SARS-CoV2, which facilitates neuroinvasion by the virus within the central or peripheral nervous systems. These molecules directly interact with various COVID-19-related molecules, such as specific regions of the spike protein (major immune element of SARS-CoV2), vascular endothelial growth factor (VEGF) receptors, VEGFR1/2, and ANGPTL4 (regulator of vessel permeability and integrity). NRPs mainly play a role in hyperinflammatory injury of the CNS and lungs, and also the liver, kidney, pancreas, and heart in COVID-19 patients. New findings have suggested NRPs good candidates for pharmacotherapy of COVID-19. However, therapeutic targeting of NRP1 in COVID-19 is still in the preclinical phase. This review presents the implications of NRP1 in multi-organ inflammation-induced injury by SARS-CoV2 and provides insights for NRP1-targeting treatments for COVID-19 patients.

Phenothiazines Inhibit SARS-CoV-2 Entry through Targeting Spike Protein

Novel coronavirus disease 2019 (COVID-19), a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has brought an unprecedented public health crisis and continues to threaten humanity due to the persistent emergence of new variants. Therefore, developing more effective and broad-spectrum therapeutic and prophylactic drugs against infection by SARS-CoV-2 and its variants, as well as future emerging CoVs, is urgently needed. In this study, we screened several US FDA-approved drugs and identified phenothiazine derivatives with the ability to potently inhibit the infection of pseudotyped SARS-CoV-2 and distinct variants of concern (VOCs), including B.1.617.2 (Delta) and currently circulating Omicron sublineages XBB and BQ.1.1, as well as pseudotyped SARS-CoV and MERS-CoV. Mechanistic studies suggested that phenothiazines predominantly inhibited SARS-CoV-2 pseudovirus (PsV) infection at the early stage and potentially bound to the spike (S) protein of SARS-CoV-2, which may prevent the proteolytic cleavage of the S protein, thereby exhibiting inhibitory activity against SARS-CoV-2 infection. In summary, our findings suggest that phenothiazines can serve as a potential broad-spectrum therapeutic drug for the treatment of SARS-CoV-2 infection as well as the infection of future emerging human coronaviruses (HCoVs).