Natural killer cells- from innate cells to the discovery of adaptability

Coley's Toxin to First Approved Therapeutic Vaccine-A Brief Historical Account in the Progression of Immunobiology-Based Cancer Treatment

Cancer immunobiology is one of the hot topics of discussion amongst researchers today, and immunotherapeutic modalities are among the selected few emerging approaches to cancer treatment that have exhibited a promising outlook. However, immunotherapy is not a new kid on the block; it has been around for centuries. The origin of cancer immunotherapy in modern medicine can be traced back to the initial reports of spontaneous regression of malignant tumors in some patients following an acute febrile infection, at the turn of the twentieth century. This review briefly revisits the historical accounts of immunotherapy, highlighting some of the significant developments in the field of cancer immunobiology, that have been instrumental in bringing back the immunotherapeutic approaches to the forefront of cancer research. Some of the topics covered are: Coley's toxin-the first immunotherapeutic; the genesis of the theory of immune surveillance; the discovery of T lymphocytes and dendritic cells and their roles; the role of tumor antigens; relevance of tumor microenvironment; the anti-tumor (therapeutic) ability of Bacillus Calmette- Guérin; Melacine-the first therapeutic vaccine engineered; theories of immunoediting and immunophenotyping of cancer; and Provenge-the first FDA-approved therapeutic vaccine. In this review, head and neck cancer has been taken as the reference tumor for narrating the progression of cancer immunobiology, particularly for highlighting the advent of immunotherapeutic agents.

Innate immune response in COVID-19: single-cell multi-omics profile of NK lymphocytes in a clinical case series

BACKGROUND

COVID-19 pandemic caused by the Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) represents the biggest global health emergency in recent decades. The host immune response to SARS-CoV-2 seems to play a key role in disease pathogenesis and clinical manifestations, with Natural Killer (NK) lymphocytes being among the targets of virus-induced regulation.

METHODS

This study performed a single-cell multi-omics analysis of transcripts and proteins of NK lymphocytes in COVID-19 patients, for the characterization of the innate immunological response to infection. NK cells were isolated from peripheral blood samples collected from adult subjects divided into 3 study groups: (1) non-infected subjects (Naïve group, n = 3), (2) post COVID-19 convalescent subjects (Healed group, n = 3) and (3) patients that were vaccinated against SARS-CoV-2 (Vaccine group, n = 3). Cells were then analysed by the BD Rhapsody System for the single-cell multi-omics investigation of transcriptome and membrane proteins.

RESULTS

The bioinformatic analysis identified 5 cell clusters which differentially expressed gene/protein markers, defining NK cell subsets as "Active NK cells" and "Mature NK cells". Calculating the relative proportion of each cluster within patient groups, more than 40% of the Naïve group cell population was found to belong to Mature NKs, whereas more than 75% of the Vaccine group cell population belonged to the cluster of Active NKs. Regarding the Healed group, it seemed to show intermediate phenotype between Active and Mature NK cells. Differential expression of specific genes, proteins and signaling pathways was detected comparing the profile of the 3 experimental groups, revealing a more activated NK cell phenotype in vaccinated patients versus recovered individuals.

CONCLUSIONS

The present study detected differential expression of NK cell markers in relation to SARS-CoV-2 infection and vaccine administration, suggesting the possibility to identify key molecular targets for clinical-diagnostic use of the individual response to viral infection and/or re-infection.

Cytokine Response of Natural Killer Cells to Hepatitis B Virus Infection Depends on Monocyte Co-Stimulation

Hepatitis B virus (HBV) is a major driver of chronic hepatic inflammation, which regularly leads to liver cirrhosis or hepatocellular carcinoma. Immediate innate immune cell response is crucial for the rapid clearance of the infection. Here, natural killer (NK) cells play a pivotal role in direct cytotoxicity and the secretion of antiviral cytokines as well as regulatory function. The aim of this study was to further elucidate NK cell responses triggered by an HBV infection. Therefore, we optimized HBV in vitro models that reliably stimulate NK cells using hepatocyte-like HepG2 cells expressing the Na+-taurocholate co-transporting polypeptide (NTCP) and HepaRG cells. Immune cells were acquired from healthy platelet donors. Initially, HepG2-NTCP cells demonstrated higher viral replication compared to HepaRG cells. Co-cultures with immune cells revealed increased production of interferon-γ and tumor necrosis factor-α by NK cells, which was no longer evident in isolated NK cells. Likewise, the depletion of monocytes and spatial separation from target cells led to the absence of the antiviral cytokine production of NK cells. Eventually, the combined co-culture of isolated NK cells and monocytes led to a sufficient cytokine response of NK cells, which was also apparent when communication between the two immune cell subpopulations was restricted to soluble factors. In summary, our study demonstrates antiviral cytokine production by NK cells in response to HBV+ HepG2-NTCP cells, which is dependent on monocyte bystander activation.

Innate lymphoid cells (ILCs) in teleosts against data on ILCs in humans

It is assumed that cells corresponding to innate lymphoid cells (ILCs) in humans, in addition to lymphoid tissue inducer cells (LTi), are also found in teleosts. In this systematic group of organisms, however, they are a poorly understood cell population. In contrast to the data on ILCs in humans, which also remain incomplete despite advanced research, in teleosts, these cells require much more attention. ILCs in teleosts have been presented as cells that may be evolutionary precursors of NK cells or ILCs identified in mammals, including humans. It is a highly heterogeneous group of cells in both humans and fish and their properties, as revealed by studies in humans, are most likely to remain strictly dependent on the location of these cells and the physiological state of the individual from which they originate. They form a bridge between innate and adaptive immunity. The premise of this paper is to review the current knowledge of ILCs in teleosts, taking into account data on similar cells in humans. A review of the knowledge concerning these particular cells, elements of innate immunity mechanisms as equivalent to, or perhaps dominant over, adaptive immunity mechanisms in teleosts, as presented, may inspire the need for further research.

Natural Killer Cells and Cytotoxic T Cells: Complementary Partners against Microorganisms and Cancer

Natural killer (NK) cells and cytotoxic T (CD8+) cells are two of the most important types of immune cells in our body, protecting it from deadly invaders. While the NK cell is part of the innate immune system, the CD8+ cell is one of the major components of adaptive immunity. Still, these two very different types of cells share the most important function of destroying pathogen-infected and tumorous cells by releasing cytotoxic granules that promote proteolytic cleavage of harmful cells, leading to apoptosis. In this review, we look not only at NK and CD8+ T cells but also pay particular attention to their different subpopulations, the immune defenders that include the CD56+CD16dim, CD56dimCD16+, CD57+, and CD57+CD16+ NK cells, the NKT, CD57+CD8+, and KIR+CD8+ T cells, and ILCs. We examine all these cells in relation to their role in the protection of the body against different microorganisms and cancer, with an emphasis on their mechanisms and their clinical importance. Overall, close collaboration between NK cells and CD8+ T cells may play an important role in immune function and disease pathogenesis. The knowledge of how these immune cells interact in defending the body against pathogens and cancers may help us find ways to optimize their defensive and healing capabilities with methods that can be clinically applied.

Emerging roles of plasmacytoid dendritic cell crosstalk in tumor immunity

Plasmacytoid dendritic cells (pDCs) are a pioneer cell type that produces type I interferon (IFN-I) and promotes antiviral immune responses. However, they are tolerogenic and, when recruited to the tumor microenvironment (TME), play complex roles that have long been a research focus. The interactions between pDCs and other components of the TME, whether direct or indirect, can either promote or hinder tumor development; consequently, pDCs are an intriguing target for therapeutic intervention. This review provides a comprehensive overview of pDC crosstalk in the TME, including crosstalk with various cell types, biochemical factors, and microorganisms. An in-depth understanding of pDC crosstalk in TME should facilitate the development of novel pDC-based therapeutic methods.