Hydrogen sulfide (H₂S) has arisen as a critical gasotransmitter signaling molecule modulating cellular biological events related to health and diseases in heart, brain, liver, vascular systems and immune response. Three enzymes mediate the endogenous production of H₂S: cystathione β-synthase (CBS), cystathione γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST). CBS and CSE localizations are organ-specific. 3-MST is a mitochondrial and cytosolic enzyme. The generation of H₂S is firmly regulated by these enzymes under normal physiological conditions. Recent studies have highlighted the role of H₂S in cellular redox homeostasis, as it displays significant antioxidant properties. H₂S exerts antioxidant effects through several mechanisms, such as quenching reactive oxygen species (ROS) and reactive nitrogen species (RNS), by modulating cellular levels of glutathione (GSH) and thioredoxin (Trx-1) or increasing expression of antioxidant enzymes (AOE), by activating the transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2). H₂S also influences the activity of the histone deacetylase protein family of sirtuins, which plays an important role in inhibiting oxidative stress in cardiomyocytes and during the aging process by modulating AOE gene expression. This review focuses on the role of H₂S in NRF2 and sirtuin signaling pathways as they are related to cellular redox homeostasis.

Exposure to environmental tobacco smoke (ETS) is a known risk factor for the development of chronic lung diseases, cancer, and the exacerbation of viral infections. Extracellular vesicles (EVs) have been identified as novel mediators of cell–cell communication through the release of biological content. Few studies have investigated the composition/function of EVs derived from human airway epithelial cells (AECs) exposed to cigarette smoke condensate (CSC), as surrogates for ETS. Using novel high-throughput technologies, we identified a diverse range of small noncoding RNAs (sncRNAs), including microRNA (miRNAs), Piwi-interacting RNA (piRNAs), and transfer RNA (tRNAs) in EVs from control and CSC-treated SAE cells. CSC treatment resulted in significant changes in the EV content of miRNAs. A total of 289 miRNAs were identified, with five being significantly upregulated and three downregulated in CSC EVs. A total of 62 piRNAs were also detected in our EV preparations, with five significantly downregulated and two upregulated in CSC EVs. We used TargetScan and Gene Ontology (GO) analysis to predict the biological targets of hsa-miR-3913-5p, the most represented miRNA in CSC EVs. Understanding fingerprint molecules in EVs will increase our knowledge of the relationship between ETS exposure and lung disease, and might identify potential molecular targets for future treatments.

Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory tract infections in children and elderly. No vaccine or effective treatment is currently available for RSV. Extracellular vesicles (EVs) are microvesicles known to carry biologically active molecules, including RNA, DNA and proteins (i.e. cargo). Viral infections can induce profound changes in EV cargo, and the cargo can modulate cellular responses of recipient cells. We have recently shown that EVs isolated from RSV-infected cells were able to activate innate immune response by inducing cytokine and chemokine release from human monocytes and airway epithelial cells, however, we did not investigate the potential antiviral contribution of EVs to a subsequent infection. The objective of this study was to assess the presence of innate immune mediators, including type I and III interferons (IFNs) in EVs released from airway epithelial cells infected with RSV, and their potential role in modulating viral replication in recipient cells. EV-derived from cells infected with RSV were associated with significant amounts of cytokine and chemokines, as well as IFN-β and -λ, compared to EVs isolated from mock-infected cells. Cells treated with RSV-EVs showed significantly lower levels of viral replication compared to untreated or mock-EV-treated RSV infected cells. Cellular pretreatment with Cerdulatinib, an IFN receptor signaling inhibitor, inhibited the antiviral activity of RSV-EVs in recipient airway epithelial cells. Furthermore, treatment of A549 cells with RSV-EVs induced the expression of IFN-dependent antiviral genes, supporting the idea that RSV-EVs exerts their antiviral activity through an interferon-dependent mechanism. Finally, we determined the concentrations of soluble and EV-associated IFN-β and IFN-λ in five nasopharyngeal secretions (NPS) of children with viral infections. There were significant levels of IFN-λ in NPS and NPS-derived EVs, while IFN-β was not detected in either of the two types of samples. EVs released from RSV-infected cells could represent a potential therapeutic approach for modulating RSV replication in the airways.

Respiratory syncytial virus (RSV) is the leading cause of respiratory infections in children. Extracellular vesicles (EVs), released by airway epithelial cells, contain proteins and different families of non-coding RNAs (EV cargo) that can modulate the responses of target cells to viral infection. Nasal mucosa is a primary site of viral entry and the source of EVs present in the upper airway secretions. In this study we characterized proteins, including inflammatory mediators and cytokines, and the piwi-interacting RNA (piRNAs) cargo of EVs isolated from pediatric human nose organoids (HNO) and nasopharyngeal secretions (NPS) positive for RSV. Using Proximity Extension Assay (PEA) and Luminex multi-target arrays, we found significant enrichment in several chemokines and other mediators/biomarkers, including CCL2, CCL20, CXCL5, CX3CL1, CXCL6, MMP-1, MMP-10, uPA, Flt3L, ARNT and CD40 in EVs secreted by RSV-infected HNO compared to control mock HNO. Analysis of NPS samples from RSV infected children revealed that CCL3, CCL20, CXCL8, uPA, VEGFA, were concentrated in the NPS-EV fraction. LC-MS/MS and Gene Ontology indicated that RSV positive NPS-EVs originate from different cellular sources, with the most abundant proteins from neutrophils and epithelial cells. A total of 490 piRNAs were detected by NGS sequencing of small RNA libraries obtained from NPS-EVs, which has not been reported prior to this study. Identification of inflammatory mediators and small non-coding RNAs which are compartmentalized in EVs contributes to understanding mechanisms of virus-mediated pathogenesis in RSV infections.

End-stage liver disease (ESLD), affecting millions worldwide, represents a challenging issue for clinical research and global public health. Liver transplantation is the gold standard therapeutic approach but shows some drawbacks. Hepatocyte transplantation could be a reliable alternative for patient treatment. Mesenchymal stromal cells derived from Wharton’s jelly of the umbilical cord (WJ-MSCs) can differentiate into hepatocyte-like cells (HLCs) and show immunomodulatory functions. Due to the increasing demand for fully characterized cell therapy vehicles warranting both the safety and efficacy of treatments, in this work, we extensively characterized WJ-MSCs before and after the application of a hepatocyte-directed differentiation protocol. HLCs exhibited a morphology resembling that of hepatocytes, expressed early and late hepatic markers (α-fetoprotein, albumin, CK18, HNF4-α), and acquired hepatic functions (glycogen synthesis, xenobiotics detoxification), as also revealed by the shotgun proteomics approach. HLCs maintained the same pattern of immunomodulatory molecule expression and mesenchymal markers, other than displaying specific enzymes, suggesting these cells as promising candidates for cellular therapy of ESLD. Our work shed new light on the basic biology of HLCs, suggesting new therapeutic approaches to treat ESLD.