ATN Ac PHSCN NH is a small peptide antagonist of

ATN-161 (Ac-PHSCN-NH2) is a small peptide antagonist of integrin α5β1, a recently developed anticancer drug that interacts with the N-terminus of the β1 region of integrin α5β1 to lock integrin α5β1 in its non-activated conformation (Wang et al., 2016). The drug has been tested in Phase 2 clinical trials and can lead to stable disease in patients with solid tumors (Kaemmerer et al., 2014). However, it is unclear whether ATN-161 has antiviral effects on PHEV. In this study, we demonstrated that ATN-161 had an antiviral effect and explored potential mechanisms of action.
Materials and methods
Results
Discussion Integrins are members of a family of cell adhesion molecules that provide a link between extracellular matrix (ECM) proteins and microcystin lr cytoskeletal proteins, essential for regulating cytoskeleton and intracellular signaling pathways, which are all essential for cell survival, proliferation, shape necessities, attachment, migration, and angiogenesis (Parolin et al., 2018). Approximately 24 integrins have been identified. These heterodimeric receptor molecules are derived from different pairs between the 18a and 8b subunits (Niu and Li, 2017). With the role of integrin in cerebrovascular diseases has been proposed, it is closely related to multiple stages of neurodevelopment and a variety of neuropathological processes (Sun et al., 2017; Welser et al., 2017). Furthermore, many pathogens have the ability to invade cells using integrin with different mechanisms, including viruses and bacteria (Kim et al., 2018; Morris et al., 2018). Virus-integrin binding has been shown to promote adhesion, cytoskeletal rearrangement, integrin activation and increased intracellular signaling (Hussein et al., 2015). HIV-1 interacts with integrin a4b7 via gp120, which is essential for efficient intercellular transmission of the virus (Lertjuthaporn et al., 2018). Therefore, the treatment of targeting integrins has received more and more attention. PHEV is a typical neurotropic virus that can cause extensive neurological damage in infected host animals (Li et al., 2018). In the brain tissue of the mouse infection model, neuronal edema, swelling of the cell body, partial dissolution of the Nissl body, concentration of the neuron nuclei, and severe staining were observed (Lan et al., 2014). Integrin α5β1 is an important member of the integrin family and is essential for angiogenesis, neurological recovery, etc (Lu et al., 2018; Sui et al., 2018). Integrin α5β1 has been shown to be associated with many viral invasion of host cells, such as Human Immunodeficiency Virus (HIV), Ebola virus, Epstein-Barr virus (EBV) (Hussein et al., 2015). Previous studies have demonstrated that PHEV can promote its entry into N2a cells through integrin α5β1 pathway (Lv et al., 2019). But, the role of integrin α5β1 pathway in vivo is not clear. In this article, we detected that the expression level of integrin α5β1 in PHEV-infected mice and found an increased expression in mice. This was consistent with the results that in vitro (Lv et al., 2019). It is suggested that there was a close relationship between integrin α5β1 and PHEV proliferation in vivo. To further investigate the role of integrin α5β1 in the proliferation of PHEV in vivo, we used ATN-161 to inhibit the expression of integrin α5β1 and analyzed the effect of inhibitor on PHEV proliferation and its therapeutic effect. ATN-161 is a non-RGD-based integrin-binding peptide that targets α5β1. It inhibits the migration and adhesion of specific integrins on activated endothelial cells, which plays a key role in tumor angiogenesis (Wang et al., 2016). However, whether ATN-161 has antiviral effects has not been reported. After ATN-161 treatment of mice, the expression of PHEV in mouse brain decreased by 50%-70%. In addition, ATN-161 treatment delayed the onset of mice, reduced symptoms, decreased weight loss, and significantly prolonged survival. Histological observations showed that the neuronal cells of ATN-161 treated mice tend to be normal, and there were no typical non-suppurative encephalitis symptoms at 5 dpi. The number of PHEV-positive neurons in ATN-161 treated mice was also significantly reduced by indirect immunofluorescence. The above experiments confirmed that integrin α5β1 promoted PHEV proliferation in vivo and ATN-161 had a certain antiviral effect. This experiment provides a theoretical basis for the development of clinical antiviral drugs targeting integrin α5β1.