Human rhinovirus 16 induces antiviral and inflammatory response in the human vascular endothelium

Human lung vascular endothelium may limit infection with HRV16 via IFN-β-dependent mechanisms

Human rhinovirus 16 (HRV16) may induce inflammatory and antiviral responses in the human lung vascular endothelium (ECs) and impair its barrier functions after infection. However, ECs may regain barrier and metabolic functions. Mechanisms of limitation of HRV16 infection in the lung vascular endothelium are unknown. Human lung vascular endothelium (HMVEC-L) was infected with HRV16. IFN-β, OAS-1, and PKR expression was assessed by real-time PCR, flow cytometry, and confocal microscope. To prove the significance of IFN-β in the limitation of HRV16 replication, HMVEC-Ls were preincubated with anti-IFN-β Abs. To prove the involvement of OAS-1 and PKR in the IFN-dependent limitation of HRV16 replication, HMVEC-Ls were transfected with respective siRNA. HRV16 stimulated IFN-β production and activated intracellular mechanisms of antiviral immunity based on OAS-1 and PKR activation. Blocking of IFN-β contributed to the inhibition of intracellular mechanisms of antiviral immunity (OAS-1, PKR) and boosted replication of HRV16. Effective OAS-1 silencing by siRNA caused the increase of HRV16 copy numbers after HRV16 infection. siRNA upregulated the other genes related to the antiviral response. The infected lung vascular endothelium may limit the HRV16 infection. This limitation may be associated with the induction of IFN-β-dependent intracellular mechanisms based on OAS-1 and PKR activity.

Rhinovirus induces airway remodeling: what are the physiological consequences?

BACKGROUND

Rhinovirus infections commonly evoke asthma exacerbations in children and adults. Recurrent asthma exacerbations are associated with injury-repair responses in the airways that collectively contribute to airway remodeling. The physiological consequences of airway remodeling can manifest as irreversible airway obstruction and diminished responsiveness to bronchodilators. Structural cells of the airway, including epithelial cells, smooth muscle, fibroblasts, myofibroblasts, and adjacent lung vascular endothelial cells represent an understudied and emerging source of cellular and extracellular soluble mediators and matrix components that contribute to airway remodeling in a rhinovirus-evoked inflammatory environment.

MAIN BODY

While mechanistic pathways associated with rhinovirus-induced airway remodeling are still not fully characterized, infected airway epithelial cells robustly produce type 2 cytokines and chemokines, as well as pro-angiogenic and fibroblast activating factors that act in a paracrine manner on neighboring airway cells to stimulate remodeling responses. Morphological transformation of structural cells in response to rhinovirus promotes remodeling phenotypes including induction of mucus hypersecretion, epithelial-to-mesenchymal transition, and fibroblast-to-myofibroblast transdifferentiation. Rhinovirus exposure elicits airway hyperresponsiveness contributing to irreversible airway obstruction. This obstruction can occur as a consequence of sub-epithelial thickening mediated by smooth muscle migration and myofibroblast activity, or through independent mechanisms mediated by modulation of the β2 agonist receptor activation and its responsiveness to bronchodilators. Differential cellular responses emerge in response to rhinovirus infection that predispose asthmatic individuals to persistent signatures of airway remodeling, including exaggerated type 2 inflammation, enhanced extracellular matrix deposition, and robust production of pro-angiogenic mediators.

CONCLUSIONS

Few therapies address symptoms of rhinovirus-induced airway remodeling, though understanding the contribution of structural cells to these processes may elucidate future translational targets to alleviate symptoms of rhinovirus-induced exacerbations.

Human lung vascular endothelium may limit viral replication and recover in time upon the infection with rhinovirus HRV16

Vascular endothelium is a semi-permeable barrier that regulates the flow of nutrients, ions, cytokines, and immune cells between blood and tissues. Barrier properties of endothelium, its ability to regenerate, and the potential for secretion of inflammatory mediators play a crucial role in maintaining local tissue homeostasis. The lung vascular endothelial cells was shown to be infected by human rhinovirus and generate antiviral, inflammatory and cytopathic responses. The current study reveals that in the long-time manner the lung vascular endothelium may efficiently limit the HRV replication via the IFN-dependent 2'-5'-oligoadenylate synthetase 1 (OAS1) activation. This leads to the restoration of integrity accompanied by the up-regulation of adherens and tight junctions, increase of metabolic activity, and proliferation rate. Secondly, HRV16-infected cells show delayed and transient up-regulation of the expression of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), angiopoietin 1 and 2, and neurophilin-1 (NRP-1), as well as VEGF receptors. The lung vascular endothelium infected with HRV may limit the infection, recover in time, and regain barrier properties and metabolic functions, thus leading to the restoration of integrated barrier tissue.

Friend or foe: RIG- I like receptors and diseases

Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), which are pivotal sensors of RNA virus invasions, mediate the transcriptional induction of genes encoding type I interferons (IFNs) and proinflammatory cytokines, successfully establishing host antiviral immune response. A few excellent reviews have elaborated on the structural biology of RLRs and the antiviral mechanisms of RLR activation. In this review, we give a basic understanding of RLR biology and summarize recent findings of how RLR signaling cascade is strictly controlled by host regulatory mechanisms, which include RLR-interacting proteins, post-translational modifications and microRNAs (miRNAs). Furthermore, we pay particular attention to the relationship between RLRs and diseases, especially how RLRs participate in SARS-CoV-2, malaria or bacterial infections, how single-nucleotide polymorphisms (SNPs) or mutations in RLRs and antibodies against RLRs lead to autoinflammatory diseases and autoimmune diseases, and how RLRs are involved in anti-tumor immunity. These findings will provide insights and guidance for antiviral and immunomodulatory therapies targeting RLRs.

Endothelial Cells as a Key Cell Type for Innate Immunity: A Focused Review on RIG-I Signaling Pathway

The vascular endothelium consists of a highly heterogeneous monolayer of endothelial cells (ECs) which are the primary target for bacterial and viral infections due to EC’s constant and close contact with the bloodstream. Emerging evidence has shown that ECs are a key cell type for innate immunity. Like macrophages, ECs serve as sentinels when sensing invading pathogens or microbial infection caused by viruses and bacteria. It remains elusive how ECs senses danger signals, transduce the signal and fulfil immune functions. Retinoic acid-inducible gene-I (RIG-I, gene name also known as DDX58) is an important member of RIG-I-like receptor (RLR) family that functions as an important pathogen recognition receptor (PRR) to execute immune surveillance and confer host antiviral response. Recent studies have demonstrated that virus infection, dsRNA, dsDNA, interferons, LPS, and 25-hydroxycholesterol (25-HC) can increase RIG-1 expression in ECs and propagate anti-viral response. Of translational significance, RIG-I activation can be inhibited by Panax notoginseng saponins, endogenous PPARγ ligand 15-PGJ2, tryptanthrin and 2-animopurine. Considering the pivotal role of inflammation and innate immunity in regulating endothelial dysfunction and atherosclerosis, here we provided a concise review of the role of RIG-I in endothelial cell function and highlight future direction to elucidate the potential role of RIG-I in regulating cardiovascular diseases as well as virus infectious disease, including COVID-19. Furthered understanding of RIG-I-mediated signaling pathways is important to control disorders associated with altered immunity and inflammation in ECs.