Protein Disulfide Isomerase A3 Regulates Influenza Neuraminidase Activity and Influenza Burden in the Lung

Suppressing ERp57 diminishes osteoclast activity and ameliorates ovariectomy-induced bone loss via the intervention in calcium oscillation and the calmodulin/calcineurin/Nfatc1 pathway

Background

Increased osteoclast activity constitutes the primary etiology of excessive bone erosion in postmenopausal osteoporosis. ERp57, otherwise referred to as protein disulfide isomerase A3 (PDIA3), plays a crucial role in the regulation of intracellular calcium signaling. This is documented to exert a profound impact on osteoclast differentiation and functionality.

Methods

To ascertain the potential role of ERp57 in disease progression, prevention, and treatment, network pharmacology and bioinformatics analyses were conducted in relation to postmenopausal osteoporosis and ERp57 inhibitor (Loc14). Then, subsequent experimental verifications were employed in vitro on osteoclast and osteoblast, and in vivo on ovariectomy (OVX) mice models.

Results

Multiple enrichment analyses suggested that the "calcium signaling pathway" may constitute a potential avenue for therapeutic intervention by Loc14 in the treatment of postmenopausal osteoporosis. In vitro experiments demonstrated inhibition of ERp57 could block osteoclast differentiation and function by interfering with the expression of osteoclast marker genes (Traf6, Nfatc1, and Ctsk). Further mechanisms studies based on calcium imaging, qPCR, and WB established that ERp57 inhibitor (Loc14) could obstruct calcium oscillation in osteoclast precursor cells (OPCs) by limiting the entry sources of cytosolic Ca2+ and interfering with calmodulin/calcineurin/Nfatc1 pathway. Evidence from Micro-CT scanning and double calcein labeling confirmed that the application of Loc14 in vivo could alleviate bone loss and partially reversed the osteogenic impairment caused by OVX in mice.

Conclusions

Our findings proved the suppressive effects of Loc14 on osteoclastogenesis via attenuating calcium oscillation and associated singling pathways, providing ERp57 as a potential therapeutic target for postmenopausal osteoporosis.

The protein disulfide isomerase A3 and osteopontin axis promotes influenza-induced lung remodelling

BACKGROUND AND PURPOSE

Fibrotic lung remodelling after a respiratory viral infection represents a debilitating clinical sequela. Studying or managing viral-fibrotic sequela remains challenging, due to limited therapeutic options and lack of understanding of mechanisms. This study determined whether protein disulfide isomerase A3 (PDIA3) and secreted phosphoprotein 1 (SPP1), which are associated with pulmonary fibrosis, can promote influenza-induced lung fibrotic remodelling and whether inhibition of PDIA3 or SPP1 can resolve viral-mediated fibrotic remodelling.

EXPERIMENTAL APPROACH

A retrospective analysis of TriNetX data sets was conducted. Serum from healthy controls and influenza A virus (IAV)-infected patients was analysed. An inhibitor of PDIA3, punicalagin, and a neutralizing antibody for SPP1 were administered in mice. Macrophage cells treated with macrophage colony-stimulating factor (M-CSF) were used as a cell culture model.

KEY RESULTS

The TriNetX data set showed an increase in lung fibrosis and decline in lung function in flu-infected acute respiratory distress syndrome (ARDS) patients compared with non-ARDS patients. Serum samples revealed a significant increase in SPP1 and PDIA3 in influenza-infected patients. Lung PDIA3 and SPP1 expression increased following viral infection in mouse models. Punicalagin administration 2 weeks after IAV infection in mice caused a significant decrease in lung fibrosis and improved oxygen saturation. Administration of neutralizing SPP1 antibody decreased lung fibrosis. Inhibition of PDIA3 decreased SPP1secretion from macrophages, in association with diminished disulfide bonds in SPP1.

CONCLUSION AND IMPLICATIONS

The PDIA3-SPP1 axis promotes post-influenza lung fibrosis in mice and that pharmacological inhibition of PDIA3 or SPP1 can treat virus-induced lung fibrotic sequela.

Venezuelan equine encephalitis virus E1 protein interacts with PDIA6 and PDI inhibition reduces alphavirus production

Venezuelan equine encephalitis virus (VEEV) is an alphavirus transmitted by mosquitos that can cause a febrile illness and induce severe neurological complications in humans and equine populations. Currently there are no FDA approved vaccines or antiviral treatments to combat VEEV. Proteomic techniques were utilized to create an interactome of the E1 fusion glycoprotein of VEEV. VEEV E1 interacted with a number of cellular chaperone proteins including protein disulfide isomerase family A member 6 (PDIA6). PDI inhibition through LOC14 and/or nitazoxanide treatment effectively decreased production of VEEV and other alphaviruses in vitro, including eastern equine encephalitis virus, Sindbis virus, and chikungunya virus. Decreased oxidoreductive capabilities of PDIs through LOC14 or nitazoxanide treatment impacted both early and late events in viral replication, including the production of non-infectious virions and decreased VEEV E1 disulfide bond formation. Results from this study identified PDIs as critical regulators of alphavirus replication and potential therapeutic targets.

Host–Pathogen Interaction 3.0

Microorganisms can interact with plants, animals and humans in many different ways, e [...]

Thiol Modifications in the Extracellular Space-Key Proteins in Inflammation and Viral Infection

Posttranslational modifications (PTMs) allow to control molecular and cellular functions in response to specific signals and changes in the microenvironment of cells. They regulate structure, localization, stability, and function of proteins in a spatial and temporal manner. Among them, specific thiol modifications of cysteine (Cys) residues facilitate rapid signal transduction. In fact, Cys is unique because it contains the highly reactive thiol group that can undergo different reversible and irreversible modifications. Upon inflammation and changes in the cellular microenvironment, many extracellular soluble and membrane proteins undergo thiol modifications, particularly dithiol-disulfide exchange, S-glutathionylation, and S-nitrosylation. Among others, these thiol switches are essential for inflammatory signaling, regulation of gene expression, cytokine release, immunoglobulin function and isoform variation, and antigen presentation. Interestingly, also the redox state of bacterial and viral proteins depends on host cell-mediated redox reactions that are critical for invasion and infection. Here, we highlight mechanistic thiol switches in inflammatory pathways and infections including cholera, diphtheria, hepatitis, human immunodeficiency virus (HIV), influenza, and coronavirus disease 2019 (COVID-19).