Natural killer cells and their exosomes in viral infections and related therapeutic approaches: where are we?

Elevated levels of CD56+ T Cells, CD16+ CD56+ T Cells, and CD56dim NK Cells in herpes simplex virus type 1 seropositive healthy individuals

OBJECTIVES

To investigate the numbers of natural killer (NK) cells, CD56+ T-cells and CD56- T cells, and the levels ofCD16 in healthy individuals seropositive for herpes simplex virus Type 1 (HSV-1). Specifically, it seeks to measure the levels of these cells to learn about the possible immunological significance during HSV-1 seropositive status.

METHODS

This study employed a cross-sectional research design to examine the levels of CD56+ T-cells and CD16+ among individuals seropositive for herpes simplex virus type 1 (HSV-1) in Taif city. A total of 112 participants were enrolled, with HSV-1 serostatus determined via ELISA, and cellular evaluation conducted using flow cytometry. The study was performed between January 2023 to July 2023.

RESULTS

Our study found 36% HSV-1 seropositivity, contrasting with higher rates in Saudi Arabia. No significant age or gender differences were observed. HSV-1 seropositive individuals showed elevated dim CD56 NK cells and CD56+ T-cells, aligning with prior research on lymphocyte infiltration during HSV-1 activation. Further investigation is warranted for CD56- T-cells and bright NK cells.

CONCLUSION

HSV-1 seropositive individuals showed elevated dim CD56 NK cells and CD56+ T-cells, consistent with lymphocyte activities during viral activation. CD16 expression on CD56+ T-cells suggests their involvement in viral defence, emphasizing the need for further investigation into immune responses against HSV-1.

Reprogramming tumor-associated macrophages using exosomes from M1 macrophages

Macrophages, abundant in tumors, are classified as M1 or M2 types with M2 dominating the tumor microenvironment. Shifting macrophages from M2 to M1 using exosomes is a promising intervention. The properties of exosomes depend on their source cells. M1-exosomes are expected to polarize macrophages towards M1 phenotype. We compared M1-exosomes and M0-exosomes' effects on M2 macrophage polarization. The RAW264.7 cells were cultured and one group of them was exposed to LPS. The serum-free medium was collected and exosomes were extracted. Exosomes were analyzed by scanning and transmission electron microscopy, dynamic light scattering and Western blot. Subsequently, M1 or M0 exosomes were applied to M2 macrophages induced by IL4. The macrophages polarization, including M1 and M2 genes and surface markers expression, cytokines secretion, and phagocytosis ability were evaluated. It was demonstrated that M1-exosomes induced macrophage polarization toward the M1 phenotype, characterized by an upregulation of M1-specific markers and a downregulation of M2 markers. Furthermore, the secretion of TNF-α was increased, while the secretion of IL-10 was decreased. The phagocytosis ability of M1-exosome-treated macrophages was also augmented. This research suggested that M1-exosomes might be promising candidates for modulating immune response in situations marked by an overabundance of M2 polarization, like in cancer.

Ethanolic Extract from Echinacea purpurea (L.) Moench Inhibits Influenza A/B and Respiratory Syncytial Virus Infection in vitro: Preventive Agent for Viral Respiratory Infections

Among the most frequent causes of respiratory infections in humans are influenza A virus H1N1 (H1N1), influenza B virus (IVB), and respiratory syncytial virus (RSV). Echinacea is a perennial wildflower belonging to the Asteraceae family. Echinacea purpurea (L.) Moench is a species belonging to the Echinacea genus. Its characteristic compound, chicoric acid (CA), is known for its physiological activities, including antiviral effects and immune enhancement. Activities of E. purpurea 60% ethanol extract (EPE) and CA in inhibiting infections caused by H1N1, IVB, and RSV subtype A (RSV-A) were evaluated through plaque inhibition tests, quantification of viral gene expression, and analysis of transmission electron microscopy (TEM) images. Additionally, inhibitory activities of EPE and CA for hemagglutination and neuraminidase (NA) of H1N1 and IVB were determined. In the plaque reduction assays, both EPE and CA reduced infectivity against H1N1, IVB, and RSV-A. Furthermore, quantitative real-time polymerase chain reaction analysis revealed that EPE and CA reduced gene expression levels for H1N1, IVB, and RSV-A, whereas TEM image analysis confirmed their inhibitory effects on host cell infection by these viruses. Hemagglutination assays exhibited the ability of EPE and CA to hinder H1N1 and IVB attachment to host cell receptors. Furthermore, EPE and CA displayed inhibition activity against the NA of H1N1 and IVB. These findings suggest that EPE and CA can suppress the infection and propagation of H1N1, IVB, and RSV-A, demonstrating their potential as preventive and therapeutic agents for viral respiratory infections or as ingredients for health functional foods.

MicroRNA-enriched exosome as dazzling dancer between cancer and immune cells

Exosomes are widely recognized for their roles in numerous biological processes and as intercellular communication mediators. Human cancerous and normal cells can both produce massive amounts of exosomes. They are extensively dispersed in tumor-modeling animals' pleural effusions, ascites, and plasma from people with cancer. Tumor cells interact with host cells by releasing exosomes, which allow them to interchange various biological components. Tumor growth, invasion, metastasis, and even tumorigenesis can all be facilitated by this delicate and complex system by modifying the nearby and remote surroundings. Due to the existence of significant levels of biomolecules like microRNA, exosomes can modulate the immune system's stimulation or repression, which in turn controls tumor growth. However, the role of microRNA in exosome-mediated communication between immunological and cancer cells is still poorly understood. This study aims to get the most recent information on the "yin and yang" of exosomal microRNA in the regulation of tumor immunity and immunotherapy, which will aid current cancer treatment and diagnostic techniques.

Sofosbuvir (+) daclatasvir (+) ribavirin in Egyptian patients with hepatitis C virus: Therapeutic outcomes and the prognostic role of natural killer cells

BACKGROUND

One of the prominent causes of chronic liver disease worldwide is the hepatitis C virus (HCV). HCV believed that innate immunity contributes to a sustained virological response (SVR) to the treatment of Sofosbuvir (SOF) (+) Daclatasvir (DCV) (+) Ribavirin (RBV). This study aimed to evaluate the impact of SOF (+) DCV (+) RBV therapy and persistent HCV infection on the subset of natural killer cells (NK) in HCV genotype four patients from Egypt.

MATERIALS AND METHODS

One hundred and ten patients with persistent HCV infections requiring SOF (+) DCV (+) RBV therapy were grouped, and a flow cytometry (FCM) study of the NK cell subset in peripheral blood was performed. The assessment was performed before and after three and/or six months of the cessation of viral suppression therapy when a patient had a long-term viral response (SVR). One hundred and ten volunteers from the National Liver Institute's (NLI) blood bank were selected as controls.

RESULTS

Patients with chronic HCV infection before therapy had considerably lower CD16+ and CD3- CD56+ cells than controls. Their levels increase during SOF (+) DCV (+) RBV therapy. In patients with SVR during treatment, CD16+ and CD3- CD56+ cells increased significantly compared to those who did not get SVR. Furthermore, CD56+ cells were significantly higher in patients with persistent infection before treatment than controls but diminished with the response to treatment.

CONCLUSION

NK cell activation following SOF (+) DCV (+) RBV therapy and polarization to cytotoxicity occurred early in HCV antiviral therapy and was elevated in the respondents. Our data illustrated that establishing an inhibitory cytotoxic NK profile is related to therapeutic outcomes.

Oncoviral Infections and Small Extracellular Vesicles

Small extracellular vesicles (sEV) are small membrane-bound nanovesicles with a size range below 200 nm that are released by all types of cells. sEV carry a diverse cargo of proteins, lipids, glycans, and nucleic acids that mimic the content of producer cells. sEV mediate intercellular communication and play a key role in a broad variety of physiological and pathological conditions. Recently, numerous reports have emerged examining the role of sEV in viral infections. A significant number of similarities in the sEV biogenesis pathways and the replication cycles of viruses suggest that sEV might influence the course of viral infections in diverse ways. Besides directly modulating virus propagation by transporting the viral cargo (complete virions, proteins, RNA, and DNA), sEV can also modify the host antiviral response and increase the susceptibility of cells to infection. The network of mutual interactions is particularly complex in the case of oncogenic viruses, deserving special consideration because of its significance in cancer progression. This review summarizes the current knowledge of interactions between sEV and oncogenic viruses, focusing on sEV abilities to modulate the carcinogenic properties of oncoviruses.

Alginate-gelatine hydrogel microspheres protect NK cell proliferation and cytotoxicity under hypoxic conditions

AIMS

This study aimed to encapsulate natural killer (NK) cells in a hydrogel to sustain their function within the hypoxic tumour microenvironments.

METHODS

An alginate-gelatine hydrogel was generated via electrospray technology. Hydrogel biocompatibility was assessed through cell counting kit-8 and Live/Dead assays to ascertain cell. Moreover, we analysed lactate dehydrogenase assays to evaluate the cytotoxicity against tumours and utilised RT-qPCR to analyse cytokine gene level.

RESULTS

Alginate and gelatine formed hydrogels with diameters ranging from 489.2 ± 23.0 μm, and the encapsulation efficiency was 34.07 ± 1.76%. Encapsulated NK cells exhibited robust proliferation and tumour-killing capabilities under normoxia and hypoxia. Furthermore, encapsulation provided a protective shield against cell viability under hypoxia. Importantly, tumour-killing cytotoxicity through cytokines upregulation such as granzyme B and interferon-gamma was preserved under hypoxia.

CONCLUSION

The encapsulation of NK cells not only safeguards their viability but also reinforces anticancer capacity, countering the inhibition of activation induced by hypoxia.

Natural Killer T Cell Diversity and Immunotherapy

Invariant natural killer T cells (iNKTs), a type of unconventional T cells, share features with NK cells and have an invariant T cell receptor (TCR), which recognizes lipid antigens loaded on CD1d molecules, a major histocompatibility complex class I (MHC-I)-like protein. This interaction produces the secretion of a wide array of cytokines by these cells, including interferon gamma (IFN-γ) and interleukin 4 (IL-4), allowing iNKTs to link innate with adaptive responses. Interestingly, molecules that bind CD1d have been identified that enable the modulation of these cells, highlighting their potential pro-inflammatory and immunosuppressive capacities, as required in different clinical settings. In this review, we summarize key features of iNKTs and current understandings of modulatory α-galactosylceramide (α-GalCer) variants, a model iNKT cell activator that can shift the outcome of adaptive immune responses. Furthermore, we discuss advances in the development of strategies that modulate these cells to target pathologies that are considerable healthcare burdens. Finally, we recapitulate findings supporting a role for iNKTs in infectious diseases and tumor immunotherapy.