Priming of Human Resting NK Cells by Autologous M1 Macrophages via the Engagement of IL-1β, IFN-β, and IL-15 Pathways

Circadian rhythm regulates the function of immune cells and participates in the development of tumors

Circadian rhythms are present in almost all cells and play a crucial role in regulating various biological processes. Maintaining a stable circadian rhythm is essential for overall health. Disruption of this rhythm can alter the expression of clock genes and cancer-related genes, and affect many metabolic pathways and factors, thereby affecting the function of the immune system and contributing to the occurrence and progression of tumors. This paper aims to elucidate the regulatory effects of BMAL1, clock and other clock genes on immune cells, and reveal the molecular mechanism of circadian rhythm's involvement in tumor and its microenvironment regulation. A deeper understanding of circadian rhythms has the potential to provide new strategies for the treatment of cancer and other immune-related diseases.

Immuno-Diagnostic Interest in Monitoring CD16+CD56+ (Natural Killer) Cells and CD19+CD45+ (B Lymphocytes) in Individuals Newly Diagnosed with HIV in a Tertiary Care Center

BACKGROUND/OBJECTIVE

Monitoring multiple cellular markers of immune cells may provide a more accurate evaluation of the immune status of people living with human immunodeficiency virus (PLHIV). This study assessed the value of CD16+CD56+ cells (NK cells) and CD19+ lymphocytes (B cells) phenotyping in indicating viral load, AIDS status, and treatment efficacy.

METHOD

A retrospective, laboratory-based study was conducted at the Diagnostic immunology division of a referral tertiary hospital. It involved 82 newly diagnosed HIV patients treated between 2009-2016. We explored three objectives: (1) the paired change in CD16+CD56+ and CD19+CD45+ cells counts and percentages from baseline to 2-to-6 months after treatment; (2) the association of these phenotypes with 5 gradual categories of viral load; and (3) the accuracy of CD16+CD56+ and CD19+CD45+ cells counts in indicating AIDS stage defined as CD4+ < 200 cells/mm3. The second and third objectives were tested using a pooled analysis (N = 300-373).

RESULT

The median CD19+CD45+ and CD16+CD56+ counts increased by 1.9-fold and 1.3-fold after treatment respectively (p < 0.001). A negative correlation of viral load with both CD16+CD56+ (ρ = -0.29, p < 0.001) and CD19+CD45+ (ρ = -0.34, p < 0.001) counts was observed. CD16+CD56+ count < 73 cells/mm3 and CD19+CD45+ count < 166.5 were indicative for AIDS with 95.5% and 63.6% sensitivity respectively.

CONCLUSIONS

Findings advocate for the usefulness of CD16+CD56+ and CD19+CD45+ phenotyping in characterizing the severity of HIV infection and its impact on both the humoral and cellular immunity, as well as monitoring the effectiveness of treatment.

Immune cell networking in solid tumors: focus on macrophages and neutrophils

The tumor microenvironment is composed of tumor cells, stromal cells and leukocytes, including innate and adaptive immune cells, and represents an ecological niche that regulates tumor development and progression. In general, inflammatory cells are considered to contribute to tumor progression through various mechanisms, including the formation of an immunosuppressive microenvironment. Macrophages and neutrophils are important components of the tumor microenvironment and can act as a double-edged sword, promoting or inhibiting the development of the tumor. Targeting of the immune system is emerging as an important therapeutic strategy for cancer patients. However, the efficacy of the various immunotherapies available is still limited. Given the crucial importance of the crosstalk between macrophages and neutrophils and other immune cells in the formation of the anti-tumor immune response, targeting these interactions may represent a promising therapeutic approach against cancer. Here we will review the current knowledge of the role played by macrophages and neutrophils in cancer, focusing on their interaction with other immune cells.

Yeast β-glucan modulates macrophages and improves antitumor NK-cell responses in cancer

As the largest proportion of myeloid immune cells in tumors, macrophages play an important role in tumor growth and regression according to their different phenotypes, thus reprogramming macrophages has become a new research direction for cancer immunotherapy. Yeast-derived whole β-glucan particles (WGPs) can induce M0 macrophages to differentiate into M1 macrophages and convert M2 macrophages and tumor-associated macrophages (TAMs) into M1 macrophages. In vitro, studies have confirmed that WGP-treated macrophages increase the activating receptors in natural killer cells (NK cells) and enhance the cytotoxicity of NK cells. The extracellular regulated protein kinases (ERK) signaling pathway is involved in WGP-mediated regulation of the macrophage phenotype. Further in vivo studies show that oral WGP can significantly delay tumor growth, which is related to the increased proportion of macrophages and NK cells, the macrophage phenotype reversal, and the enhancement of NK cell immune function. NK-cell depletion reduces the therapeutic efficacy of WGP in tumor-bearing mice. These findings revealed that in addition to T cells, NK cells also participate in the antitumor process of WGP. It was confirmed that WGP regulates the macrophage phenotype to regulate NK-cell function.

Derived myeloid lineage induced pluripotent stem as a platform to study human C-C chemokine receptor type 5Δ32 homozygotes

The C-C chemokine receptor type 5 (CCR5) expressed on immune cells supports inflammatory responses by directing cells to the inflammation site. CCR5 is also a major coreceptor for macrophage tropic human immunodeficiency viruses (R5-HIV-1) and its variants can confer protection from HIV infection, making it an ideal candidate to target for therapy. We developed a stepwise protocol that differentiates induced pluripotent stem cells (iPSCs) from individuals homozygous for the CCR5Δ32 variant and healthy volunteers into myeloid lineage induced monocytes (iMono) and macrophages (iMac). By characterizing iMono and iMac against their primary counterparts, we demonstrated that CCR5Δ32 homozygous cells are endowed with similar pluripotent potential for self-renewal and differentiation as iPSC lines generated from non-variant individuals while also showing resistance to HIV infection. In conclusion, these cells are a platform to investigate CCR5 pathophysiology in HIV-positive and negative individuals and to help develop novel therapies.

Tumour-associated macrophages: versatile players in the tumour microenvironment

Tumour-Associated Macrophages (TAMs) are one of the pivotal components of the tumour microenvironment. Their roles in the cancer immunity are complicated, both pro-tumour and anti-cancer activities are reported, including not only angiogenesis, extracellular matrix remodeling, immunosuppression, drug resistance but also phagocytosis and tumour regression. Interestingly, TAMs are highly dynamic and versatile in solid tumours. They show anti-cancer or pro-tumour activities, and interplay between the tumour microenvironment and cancer stem cells and under specific conditions. In addition to the classic M1/M2 phenotypes, a number of novel dedifferentiation phenomena of TAMs are discovered due to the advanced single-cell technology, e.g., macrophage-myofibroblast transition (MMT) and macrophage-neuron transition (MNT). More importantly, emerging information demonstrated the potential of TAMs on cancer immunotherapy, suggesting by the therapeutic efficiency of the checkpoint inhibitors and chimeric antigen receptor engineered cells based on macrophages. Here, we summarized the latest discoveries of TAMs from basic and translational research and discussed their clinical relevance and therapeutic potential for solid cancers.

Tumour-associated macrophages as a potential target to improve natural killer cell-based immunotherapies

Adoptive transfer of natural killer (NK) cells has been proposed as a novel immunotherapy for malignant tumours resistant to current therapeutic modalities. Several clinical studies have demonstrated that the NK cell-infusion is well tolerated without severe side effects and shows promising results in haematological malignancies. However, patients with malignant solid tumours do not show significant responses to this therapy. Such disappointing results largely arise from the inefficient delivery of infused NK cells and the impairment of their functions in the tumour microenvironment (TME). Tumour-associated macrophages (TAMs) are the most abundant stromal cells in the TME of most solid tumours, and a high TAM density correlates with poor prognosis of cancer patients. Although our knowledge of the interactions between TAMs and NK cells is limited, many studies have indicated that TAMs suppress NK cell cytotoxicity against cancer cells. Therefore, blockade of TAM functions can be an attractive strategy to improve NK cell-based immunotherapies. On the other hand, macrophages are reported to activate NK cells under certain circumstances. This essay presents our current knowledge about mechanisms by which macrophages regulate NK cell functions and discusses possible therapeutic approaches to block macrophage-mediated NK cell suppression.

M1/M2 macrophages and their overlaps - myth or reality?

Macrophages represent heterogeneous cell population with important roles in defence mechanisms and in homoeostasis. Tissue macrophages from diverse anatomical locations adopt distinct activation states. M1 and M2 macrophages are two polarized forms of mononuclear phagocyte in vitro differentiation with distinct phenotypic patterns and functional properties, but in vivo, there is a wide range of different macrophage phenotypes in between depending on the microenvironment and natural signals they receive. In human infections, pathogens use different strategies to combat macrophages and these strategies include shaping the macrophage polarization towards one or another phenotype. Macrophages infiltrating the tumours can affect the patient's prognosis. M2 macrophages have been shown to promote tumour growth, while M1 macrophages provide both tumour-promoting and anti-tumour properties. In autoimmune diseases, both prolonged M1 activation, as well as altered M2 function can contribute to their onset and activity. In human atherosclerotic lesions, macrophages expressing both M1 and M2 profiles have been detected as one of the potential factors affecting occurrence of cardiovascular diseases. In allergic inflammation, T2 cytokines drive macrophage polarization towards M2 profiles, which promote airway inflammation and remodelling. M1 macrophages in transplantations seem to contribute to acute rejection, while M2 macrophages promote the fibrosis of the graft. The view of pro-inflammatory M1 macrophages and M2 macrophages suppressing inflammation seems to be an oversimplification because these cells exploit very high level of plasticity and represent a large scale of different immunophenotypes with overlapping properties. In this respect, it would be more precise to describe macrophages as M1-like and M2-like.

Synergistic cancer immunotherapy utilizing programmed Salmonella typhimurium secreting heterologous flagellin B conjugated to interleukin-15 proteins

The use of appropriately designed immunotherapeutic bacteria is an appealing approach to tumor therapy because the bacteria specifically target tumor tissue and deliver therapeutic payloads. The present study describes the engineering of an attenuated strain of Salmonella typhimurium deficient in ppGpp biosynthesis (SAM) that could secrete Vibrio vulnificus flagellin B (FlaB) conjugated to human (hIL15/FlaB) and mouse (mIL15/FlaB) interleukin-15 proteins in the presence of L-arabinose (L-ara). These strains, named SAMphIF and SAMpmIF, respectively, secreted fusion proteins that retained bioactivity of both FlaB and IL15. SAMphIF and SAMpmIF inhibited the growth of MC38 and CT26 subcutaneous (sc) tumors in mice and increased mouse survival rate more efficiently than SAM expressing FlaB alone (SAMpFlaB) or IL15 alone (SAMpmIL15 and SAMphIL15), although SAMpmIF had slightly greater antitumor activity than SAMphIF. The mice treated with these bacteria showed enhanced macrophage phenotype shift, from M2-like to M1-like, as well as greater proliferation and activation of CD4⁺ T, CD8⁺ T, NK, and NKT cells in tumor tissues. After tumor eradication by these bacteria, ≥50% of the mice show no evidence of tumor recurrence upon rechallenge with the same tumor cells, indicating that they had acquired long-term immune memory. Treatment of mice of 4T1 and B16F10 highly malignant sc tumors with a combination of these bacteria and an immune checkpoint inhibitor, anti-PD-L1 antibody, significantly suppressed tumor metastasis and increased mouse survival rate. Taken together, these findings suggest that SAM secreting IL15/FlaB is a novel therapeutic candidate for bacterial-mediated cancer immunotherapy and that its antitumor activity is enhanced by combination with anti-PD-L1 antibody.

The role of macrophages-mediated communications among cell compositions of tumor microenvironment in cancer progression

Recent studies have revealed that tumor-associated macrophages are the most abundant stromal cells in the tumor microenvironment and play an important role in tumor initiation and progression. Furthermore, the proportion of macrophages in the tumor microenvironment is associated with the prognosis of patients with cancer. Tumor-associated macrophages can polarize into anti-tumorigenic phenotype (M1) and pro-tumorigenic phenotype (M2) by the stimulation of T-helper 1 and T-helper 2 cells respectively, and then exert opposite effects on tumor progression. Besides, there also is wide communication between tumor-associated macrophages and other immune compositions, such as cytotoxic T cells, regulatory T cells, cancer-associated fibroblasts, neutrophils and so on. Furthermore, the crosstalk between tumor-associated macrophages and other immune cells greatly influences tumor development and treatment outcomes. Notably, many functional molecules and signaling pathways have been found to participate in the interactions between tumor-associated macrophages and other immune cells and can be targeted to regulate tumor progression. Therefore, regulating these interactions and CAR-M therapy are considered to be novel immunotherapeutic pathways for the treatment of malignant tumors. In this review, we summarized the interactions between tumor-associated macrophages and other immune compositions in the tumor microenvironment and the underlying molecular mechanisms and analyzed the possibility to block or eradicate cancer by regulating tumor-associated macrophage-related tumor immune microenvironment.

Macrophage and monocyte subsets as new therapeutic targets in cancer immunotherapy

The introduction of immune checkpoint inhibitors (ICIs) for the treatment of solid cancers dramatically turned the tables in clinical routine. However, therapy success is still limited with up to 70% of non-responders in patients with ICI treatment. Traditionally, most immunotherapy approaches aim at directly stimulating anti-tumor T cell responses. More recently, tumor-associated macrophages have come into focus due to their predominance in solid tumors. Intensive cross-talk with tumor cells and immune as well as stromal cells within the tumor microenvironment can drive either pro- or anti-tumorigenic macrophage phenotypes. In turn, tumor-associated macrophages strongly shape cytokine and metabolite levels in the tumor microenvironment and thus are central players in anti-tumor immunity. Thus, ambivalent macrophage populations exist which raises therapeutic possibilities to either enhance or diminish their functionality. However, molecular signals controlling tumor-associated macrophage polarization are incompletely understood. Gaining in-depth understanding of monocyte/macrophage properties both in circulation and within distinct tumor microenvironments would (i) allow the development of new therapeutic approaches, and (ii) could additionally aid our understanding of underlying mechanisms limiting current therapy with the option of combinatorial therapies to increase efficacy. In this review, we summarize recent data addressing heterogeneity of tumor-associated macrophage populations and we discuss strategies to target macrophages using known molecular pathways with the potential for straight-forward clinical application.

Antitumor Activity of Anti-miR-21 Delivered through Lipid Nanoparticles

The ability of lipid nanoparticles (LNPs) to deliver nucleic acids have shown a great therapeutic potential to treat a variety of diseases. Here, an optimized formulation of QTsome lipid nanoparticles (QTPlus) is utilized to deliver an anti-miR-21 (AM21) against cancer. The miR-21 downstream gene regulation and antitumor activity is evaluated using mouse and human cancer cells and macrophages. The antitumor activity of QTPlus encapsulating AM21 (QTPlus-AM21) is further evaluated in combination with erlotinib and atezolizumab (ATZ). QTPlus-AM21 demonstrates a superior miR-21-dependent gene regulation and eventually inhibits A549 non-small cell lung cancer growth in vitro. QTPlus-AM21 further induces chemo-sensitization of A549 cells to erlotinib with a combination index of 0.6 in inhibiting A549 cell growth. When systemically administers to MC38 tumor-bearing mouse model, QTPlus-AM21 exhibits an antitumor immune response with over 80% tumor growth inhibition (TGI%) and over twofold and fourfold PD-1 and PD-L1 upregulation in tumors and spleens. The combination therapy of QTPlus-AM21 and ATZ further shows a higher antitumor response (TGI% over 90%) and successfully increases M1 macrophages and CD8 T cells into TME. This study provides new insights into the antitumor mechanism of AM21 and shows great promise of QTPlus-AM21 in combination with chemotherapies and immunotherapies.

Macrophage polarization in kidney transplant patients

BACKGROUND

Macrophages can oscillate between two functionally distinct states: proinflammatory M1 and anti-inflammatory M2. Classically- activated M1 macrophages produce proinflammatory cytokines (TNF-α, IFN-ƴ, and IL-6), which ares associated with graft dysfunction/rejections. In contrast, alternatively-activated macrophages M2 produce anti-inflammatory cytokines (IL-10) that are involved in host defense, tissue repair/remodeling, debris scavenging, and immune regulation, thereby helps to improve long-term graft survival.

METHODS

In this study, we have identified graft dysfunction or rejection by biopsies using immunohistochemistry. Flow cytometry was used to detect M1 (CD163+, CD206+, and CD200R+) and M2 (CD86+, CD80+, and CD68+) macrophages. Enzyme-linked immunosorbent assay (ELISA) was used to measure a panel of cytokines.

RESULTS

Histological analysis of the kidney transplants (n = 30) was used to distinguish those with acute/chronic allograft rejection (n = 15) from those with stable kidney function (n = 15). Flow cytometry results showed that patients with graft rejection exhibited macrophages with decreased expression (33.28%) of M2 macrophage markers (CD163+, CD206+, and CD200R+) and reduced production of IL-10 (as detected using ELISA). However, 71.33% of the macrophages were found to have M1 markers (CD86+, CD80+, and CD68+; p = 0.002) and produced proinflammatory cytokines (TNF-α, IFN-ƴ, and IL-6) by ELISA (p = 0.001) when compared with the healthy control group. In contrast, stable kidney transplants had 65.58% M2 and 27.66% M1 macrophages (p = 0.03) and produced IL-10. These findings suggest that M1 macrophages dominate in kidney grafts with dysfunction or rejection, whereas M2 macrophages dominate in kidney grafts with stable function.

CONCLUSION

Our observations implicate a major shift towards M2 macrophages in stable kidney transplants, which are markedly downregulated in patients with graft dysfunction or rejection. In contrast, an increased frequency of M1 macrophages remained dominant in the pathophysiology of kidney transplants undergoing active dysfunction or rejection.

Macrophage subsets and their role: co-relation with colony-stimulating factor-1 receptor and clinical relevance

Macrophages are one of the first innate immune cells to reach the site of infection or injury. Diverse functions from the uptake of pathogen or antigen, its killing, and presentation, the release of pro- or anti-inflammatory cytokines, activation of adaptive immune cells, clearing off tissue debris, tissue repair, and maintenance of tissue homeostasis have been attributed to macrophages. Besides tissue-resident macrophages, the circulating macrophages are recruited to different tissues to get activated. These are highly plastic cells, showing a spectrum of phenotypes depending on the stimulus received from their immediate environment. The macrophage differentiation requires colony-stimulating factor-1 (CSF-1) or macrophage colony-stimulating factor (M-CSF), colony-stimulating factor-2 (CSF-2), or granulocyte–macrophage colony-stimulating factor (GM-CSF) and different stimuli activate them to different phenotypes. The richness of tissue macrophages is precisely controlled via the CSF-1 and CSF-1R axis. In this review, we have given an overview of macrophage origin via hematopoiesis/myelopoiesis, different phenotypes associated with macrophages, their clinical significance, and how they are altered in various diseases. We have specifically focused on the function of CSF-1/CSF-1R signaling in deciding macrophage fate and the outcome of aberrant CSF-1R signaling in relation to macrophage phenotype in different diseases. We further extend the review to briefly discuss the possible strategies to manipulate CSF-1R and its signaling with the recent updates.

Major pathways involved in macrophage polarization in cancer

Macrophages play an important role in tissue homeostasis, tissue remodeling, immune response, and progression of cancer. Consequently, macrophages exhibit significant plasticity and change their transcriptional profile and function in response to environmental, tissue, and inflammatory stimuli resulting in pro- and anti-tumor effects. Furthermore, the categorization of tissue macrophages in inflammatory situations remains difficult; however, there is an agreement that macrophages are predominantly polarized into two different subtypes with pro- and anti-inflammatory properties, the so-called M1-like and M2-like macrophages, respectively. These two macrophage classes can be considered as the extreme borders of a continuum of many intermediate subsets. On one end, M1 are pro-inflammatory macrophages that initiate an immunological response, damage tissue integrity, and dampen tumor progression by fostering robust T and natural killer (NK) cell anti-tumoral responses. On the other end, M2 are anti-inflammatory macrophages involved in tissue remodeling and tumor growth, that promote cancer cell proliferation, invasion, tumor metastasis, angiogenesis and that participate to immune suppression. These decisive roles in tumor progression occur through the secretion of cytokines, chemokines, growth factors, and matrix metalloproteases, as well as by the expression of immune checkpoint receptors in the case of M2 macrophages. Moreover, macrophage plasticity is supported by stimuli from the Tumor Microenvironment (TME) that are relayed to the nucleus through membrane receptors and signaling pathways that result in gene expression reprogramming in macrophages, thus giving rise to different macrophage polarization outcomes. In this review, we will focus on the main signaling pathways involved in macrophage polarization that are activated upon ligand-receptor recognition and in the presence of other immunomodulatory molecules in cancer.

Comprehensive overview of COVID-19-related respiratory failure: focus on cellular interactions

The pandemic outbreak of coronavirus disease 2019 (COVID-19) has created health challenges in all parts of the world. Understanding the entry mechanism of this virus into host cells is essential for effective treatment of COVID-19 disease. This virus can bind to various cell surface molecules or receptors, such as angiotensin-converting enzyme 2 (ACE2), to gain cell entry. Respiratory failure and pulmonary edema are the most important causes of mortality from COVID-19 infections. Cytokines, especially proinflammatory cytokines, are the main mediators of these complications. For normal respiratory function, a healthy air-blood barrier and sufficient blood flow to the lungs are required. In this review, we first discuss airway epithelial cells, airway stem cells, and the expression of COVID-19 receptors in the airway epithelium. Then, we discuss the suggested molecular mechanisms of endothelial dysfunction and blood vessel damage in COVID-19. Coagulopathy can be caused by platelet activation leading to clots, which restrict blood flow to the lungs and lead to respiratory failure. Finally, we present an overview of the effects of immune and non-immune cells and cytokines in COVID-19-related respiratory failure.

Natural Killer Cells in SARS-CoV-2 Infection: Pathophysiology and Therapeutic Implications

Natural Killer (NK) cells are lymphocytes of the innate immunity that play a crucial role in the control of viral infections in the absence of a prior antigen sensitization. Indeed, they display rapid effector functions against target cells with the capability of direct cell killing and antibody-dependent cell-mediated cytotoxicity. Furthermore, NK cells are endowed with immune-modulatory functions innate and adaptive immune responses via the secretion of chemokines/cytokines and by undertaking synergic crosstalks with other innate immune cells, including monocyte/macrophages, dendritic cells and neutrophils. Recently, the Coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread globally. Although the specific role of NK cells in COVID-19 pathophysiology still need to be explored, mounting evidence indicates that NK cell tissue distribution and effector functions could be affected by SARS-CoV-2 infection and that a prompt NK cell response could determine a good clinical outcome in COVID-19 patients. In this review, we give a comprehensive overview of how SARS-CoV-2 infection interferes with NK cell antiviral effectiveness and their crosstalk with other innate immune cells. We also provide a detailed characterization of the specific NK cell subsets in relation to COVID-19 patient severity generated from publicly available single cell RNA sequencing datasets. Finally, we summarize the possible NK cell-based therapeutic approaches against SARS-CoV-2 infection and the ongoing clinical trials updated at the time of submission of this review. We will also discuss how a deep understanding of NK cell responses could open new possibilities for the treatment and prevention of SARS-CoV-2 infection.

NK Cells, Monocytes and Macrophages in HIV-1 Control: Impact of Innate Immune Responses

Rapid and synchronized responses of innate immune cells are an integral part of managing viral spread in acute virus infections. In human immunodeficiency virus type 1 (HIV-1) infection, increased immune control has been associated with the expression of certain natural killer (NK) cell receptors. Further, immune activation of monocytes/macrophages and the presence of specific cytokines was linked to low levels of HIV-1 replication. In addition to the intrinsic antiviral capabilities of NK cells and monocytes/macrophages, interaction between these cell types has been shown to substantially enhance NK cell function in the context of viral infections. This review discusses the involvement of NK cells and monocytes/macrophages in the effective control of HIV-1 and highlights aspects of innate immune crosstalk in viral infections that may be of relevance to HIV-1 infection.

Cellular Origins and Pathogenesis of Gastrointestinal NK- and T-Cell Lymphoproliferative Disorders

The intestinal immune system, which must ensure appropriate immune responses to both pathogens and commensal microflora, comprises innate lymphoid cells and various T-cell subsets, including intra-epithelial lymphocytes (IELs). An example of innate lymphoid cells is natural killer cells, which may be classified into tissue-resident, CD56bright NK-cells that serve a regulatory function and more mature, circulating CD56dim NK-cells with effector cytolytic properties. CD56bright NK-cells in the gastrointestinal tract give rise to indolent NK-cell enteropathy and lymphomatoid gastropathy, as well as the aggressive extranodal NK/T cell lymphoma, the latter following activation by EBV infection and neoplastic transformation. Conventional CD4+ TCRαβ+ and CD8αβ+ TCRαβ+ T-cells are located in the lamina propria and the intraepithelial compartment of intestinal mucosa as type 'a' IELs. They are the putative cells of origin for CD4+ and CD8+ indolent T-cell lymphoproliferative disorders of the gastrointestinal tract and intestinal T-cell lymphoma, NOS. In addition to such conventional T-cells, there are non-conventional T-cells in the intra-epithelial compartment that express CD8αα and innate lymphoid cells that lack TCRs. The central feature of type 'b' IELs is the expression of CD8αα homodimers, seen in monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), which primarily arises from both CD8αα+ TCRαβ+ and CD8αα+ TCRγδ+ IELs. EATL is the other epitheliotropic T-cell lymphoma in the GI tract, a subset of which arises from the expansion and reprograming of intracytoplasmic CD3+ innate lymphoid cells, driven by IL15 and mutations of the JAK-STAT pathway.

NK Cell Anti-Tumor Surveillance in a Myeloid Cell-Shaped Environment

NK cells are innate lymphoid cells endowed with cytotoxic capacity that play key roles in the immune surveillance of tumors. Increasing evidence indicates that NK cell anti-tumor response is shaped by bidirectional interactions with myeloid cell subsets such as dendritic cells (DCs) and macrophages. DC-NK cell crosstalk in the tumor microenvironment (TME) strongly impacts on the overall NK cell anti-tumor response as DCs can affect NK cell survival and optimal activation while, in turn, NK cells can stimulate DCs survival, maturation and tumor infiltration through the release of soluble factors. Similarly, macrophages can either shape NK cell differentiation and function by expressing activating receptor ligands and/or cytokines, or they can contribute to the establishment of an immune-suppressive microenvironment through the expression and secretion of molecules that ultimately lead to NK cell inhibition. Consequently, the exploitation of NK cell interaction with DCs or macrophages in the tumor context may result in an improvement of efficacy of immunotherapeutic approaches.

Crosstalk between macrophages and natural killer cells in the tumor microenvironment

The tumor microenvironment (TME) is jointly constructed by a variety of cell types, including tumor cells, immune cells, fibroblasts, and epithelial cells, among others. The cells within the TME interact with each other and with tumor cells to influence tumor development and progression. As the most abundant immune cells in the TME, macrophages regulate the immune network by not only secreting a large amount of versatile cytokines but also expressing a series of ligands or receptors on the surface to interact with other cells directly. Due to their strong plasticity, they exert both immunostimulatory and immunosuppressive effects in the complex TME. The major effector cells of the immune system that directly target cancer cells include but are not limited to natural killer cells (NKs), dendritic cells (DCs), macrophages, polymorphonuclear leukocytes, mast cells, and cytotoxic T lymphocytes (CTLs). Among them, NK cells are the predominant innate lymphocyte subsets that mediate antitumor and antiviral responses. The activation and inhibition of NK cells are regulated by cytokines and the balance between activating and inhibitory receptors. There is an inextricable regulatory relationship between macrophages and NK cells. Herein, we systematically elaborate on the regulatory network between macrophages and NK cells through soluble mediator crosstalk and cell-to-cell interactions. We believe that a better understanding of the crosstalk between macrophages and NKs in the TME will benefit the development of novel macrophage- or NK cell-focused therapeutic strategies with superior efficacies in cancer therapy.

Gender Differences in Urothelial Bladder Cancer: Effects of Natural Killer Lymphocyte Immunity

Men are more likely to develop cancer than women. In fact, male predominance is one of the most consistent cancer epidemiology findings. Additionally, men have a poorer prognosis and an increased risk of secondary malignancies compared to women. These differences have been investigated in order to better understand cancer and to better treat both men and women. In this review, we discuss factors that may cause this gender difference, focusing on urothelial bladder cancer (UBC) pathogenesis. We consider physiological factors that may cause higher male cancer rates, including differences in X chromosome gene expression. We discuss how androgens may promote bladder cancer development directly by stimulating bladder urothelium and indirectly by suppressing immunity. We are particularly interested in the role of natural killer (NK) cells in anti-cancer immunity.

NK Cells in the Tumor Microenvironment as New Potential Players Mediating Chemotherapy Effects in Metastatic Melanoma

Until the last decade, chemotherapy was the standard treatment for metastatic cutaneous melanoma, even with poor results. The introduction of immune checkpoints inhibitors (ICIs) radically changed the outcome, increasing 5-year survival from 5% to 60%. However, there is still a large portion of unresponsive patients that would need further therapies. NK cells are skin-resident innate cytotoxic lymphocytes that recognize and kill virus-infected as well as cancer cells thanks to a balance between inhibitory and activating signals delivered by surface molecules expressed by the target. Since NK cells are equipped with cytotoxic machinery but lack of antigen restriction and needing to be primed, they are nowadays gaining attention as an alternative to T cells to be exploited in immunotherapy. However, their usage suffers of the same limitations reported for T cells, that is the loss of immunogenicity by target cells and the difficulty to penetrate and be activated in the suppressive tumor microenvironment (TME). Several evidence showed that chemotherapy used in metastatic melanoma therapy possess immunomodulatory properties that may restore NK cells functions within TME. Here, we will discuss the capability of such chemotherapeutics to: i) up-regulate melanoma cells susceptibility to NK cell-mediated killing, ii) promote NK cells infiltration within TME, iii) target other immune cell subsets that affect NK cells activities. Alongside traditional systemic melanoma chemotherapy, a new pharmacological strategy based on nanocarriers loaded with chemotherapeutics is developing. The use of nanotechnologies represents a very promising approach to improve drug tolerability and effectiveness thanks to the targeted delivery of the therapeutic molecules. Here, we will also discuss the recent developments in using nanocarriers to deliver anti-cancer drugs within the melanoma microenvironment in order to improve chemotherapeutics effects. Overall, we highlight the possibility to use standard chemotherapeutics, possibly delivered by nanosystems, to enhance NK cells anti-tumor cytotoxicity. Combined with immunotherapies targeting NK cells, this may represent a valuable alternative approach to treat those patients that do not respond to current ICIs.

Heparanase is a regulator of natural killer cell activation and cytotoxicity

Heparanase is the only mammalian enzyme capable of cleaving heparan sulfate, a glycosaminoglycan of the extracellular matrix and cell surfaces. Most immune cells express heparanase that contributes to a range of functions including cell migration and cytokine expression. Heparanase also promotes natural killer (NK) cell migration; however, its role in other NK cell functions remains to be defined. In this study, heparanase-deficient (Hpse^-/- ) mice were used to assess the role of heparanase in NK cell cytotoxicity, activation, and cytokine production. Upon challenge with the immunostimulant polyinosinic:polycytidylic acid (poly(I:C)), NK cells isolated from Hpse^-/- mice displayed impaired cytotoxicity against EO771.LMB cells and reduced levels of activation markers CD69 and NKG2D. However, in vitro cytokine stimulation of wild-type and Hpse^-/- NK cells resulted in similar CD69 and NKG2D expression, suggesting the impaired NK cell activation in Hpse^-/- mice results from elements within the in vivo niche. NK cells are activated in vivo by dendritic cells (DCs) in response to poly(I:C). Poly(I:C)-stimulated Hpse^-/- bone marrow DCs (BMDCs) expressed less IL-12, and when cultured with Hpse^-/- NK cells, less MCP-1 mRNA and protein was detected. Although cell-cell contact is important for DC-mediated NK cell activation, co-cultures of Hpse^-/- BMDCs and NK cells showed similar levels of contact to wild-type cells, suggesting heparanase contributes to NK cell activation independently of cell-cell contact with DCs. These observations define a role for heparanase in NK cell cytotoxicity and activation and have important implications for how heparanase inhibitors currently in clinical trials for metastatic cancer may impact NK cell immunosurveillance.

Tumor Secretome to Adoptive Cellular Immunotherapy: Reduce Me Before I Make You My Partner

Adoptive cellular immunotherapy using chimeric antigen receptor (CAR)-modified T cells and Natural Killer (NK) cells are common immune cell sources administered to treat cancer patients. In detail, whereas CAR-T cells induce outstanding responses in a subset of hematological malignancies, responses are much more deficient in solid tumors. Moreover, NK cells have not shown remarkable results up to date. In general, immune cells present high plasticity to change their activity and phenotype depending on the stimuli they receive from molecules secreted in the tumor microenvironment (TME). Consequently, immune cells will also secrete molecules that will shape the activities of other neighboring immune and tumor cells. Specifically, NK cells can polarize to activities as diverse as angiogenic ones instead of their killer activity. In addition, tumor cell phagocytosis by macrophages, which is required to remove dying tumor cells after the attack of NK cells or CAR-T cells, can be avoided in the TME. In addition, chemotherapy or radiotherapy treatments can induce senescence in tumor cells modifying their secretome to a known as “senescence-associated secretory phenotype” (SASP) that will also impact the immune response. Whereas the SASP initially attracts immune cells to eliminate senescent tumor cells, at high numbers of senescent cells, the SASP becomes detrimental, impacting negatively in the immune response. Last, CAR-T cells are an attractive option to overcome these events. Here, we review how molecules secreted in the TME by either tumor cells or even by immune cells impact the anti-tumor activity of surrounding immune cells.

Single-Cell RNA Sequencing Reveals Cellular and Transcriptional Changes Associated With M1 Macrophage Polarization in Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease characterized by recurrent abscesses, nodules, and sinus tracts in areas of high hair follicle and sweat gland density. These sinus tracts can present with purulent drainage and scar formation. Dysregulation of multiple immune pathways drives the complexity of HS pathogenesis and may account for the heterogeneity of treatment response in HS patients. Using transcriptomic approaches, including single-cell sequencing and protein analysis, we here characterize the innate inflammatory landscape of HS lesions. We identified a shared upregulation of genes involved in interferon (IFN) and antimicrobial defense signaling through transcriptomic overlap analysis of differentially expressed genes (DEGs) in datasets from HS skin, diabetic foot ulcers (DFUs), and the inflammatory stage of normal healing wounds. Overlap analysis between HS- and DFU-specific DEGs revealed an enrichment of gene signatures associated with monocyte/macrophage functions. Single-cell RNA sequencing further revealed monocytes/macrophages with polarization toward a pro-inflammatory M1-like phenotype and increased effector function, including antiviral immunity, phagocytosis, respiratory burst, and antibody-dependent cellular cytotoxicity. Specifically, we identified the STAT1/IFN-signaling axis and the associated IFN-stimulated genes as central players in monocyte/macrophage dysregulation. Our data indicate that monocytes/macrophages are a potential pivotal player in HS pathogenesis and their pathways may serve as therapeutic targets and biomarkers in HS treatment.

Macrophages Impair TLR9 Agonist Antitumor Activity through Interacting with the Anti-PD-1 Antibody Fc Domain

Simple Summary

We evaluated the contribution of macrophages to the effect of combinatorial immunotherapeutic treatments based on TLR9 stimulation (with CpG-ODNs) and PD-1 blockade in an ovarian cancer preclinical model. We observed a strong reduction in the antitumor efficacy of a TLR9 agonist upon anti-PD-1 antibody administration. Specifically, we found that TLR9-stimulated macrophages, through interacting with the fragment crystallizable (Fc) domain of the anti-PD-1 antibody, acquire an immunoregulatory phenotype leading to dampening of CpG-ODN antitumor effect. Since the stimulation of macrophage TLRs can be achieved not only by synthetic agonists but also by molecules present in the tumor microenvironment, the data we are presenting may represent another possible mechanism of anti-PD-1 antibody therapy resistance. Indeed, it is possible that when delivered as a monotherapy, anti-PD-1 antibody Fc domain may interact with macrophages in which TLR signaling has already been triggered by endogenous ligands, mirroring the biological effects described in the present study.

Abstract

Background. A combination of TLR9 agonists and an anti-PD-1 antibody has been reported to be effective in immunocompetent mice but the role of innate immunity has not yet been completely elucidated. Therefore, we investigated the contribution of the innate immune system to this combinatorial immunotherapeutic regimens using an immunodeficient mouse model in which the effector functions of innate immunity can clearly emerge without any interference from T lymphocytes. Methods. Athymic mice xenografted with IGROV-1 human ovarian cells, reported to be sensitive to TLR9 agonist therapy, were treated with cytosine–guanine (CpG)-oligodeoxynucleotides (ODNs), an anti-PD-1 antibody or their combination. Results. We found that PD-1 blockade dampened CpG-ODN antitumor activity. In vitro studies indicated that the interaction between the anti-PD-1 antibody fragment crystallizable (Fc) domain and macrophage Fc receptors caused these immune cells to acquire an immunoregulatory phenotype, contributing to a decrease in the efficacy of CpG-ODNs. Accordingly, in vivo macrophage depletion abrogated the detrimental effect exerted by the anti-PD-1 antibody. Conclusion. Our data suggest that if TLR signaling is active in macrophages, coadministration of an anti-PD-1 antibody can reprogram these immune cells towards a polarization state able to negatively affect the immune response and eventually promote tumor growth.

The Role of Natural Killer Cells in Soft Tissue Sarcoma: Prospects for Immunotherapy

Simple Summary

Soft-tissue sarcomas (STS) represent about 80% of sarcomas, and are a heterogeneous group of rare and malignant tumors. Morphological evaluation has been the standard model for the diagnosis of sarcomas, and even in samples with similar characteristics, they present genetic differences, which further increases the diversity of sarcomas. This variety is one of the main challenges for the classification and understanding of STS patterns, as well as for the respective treatments, which further decreases patient survival (<5 years). Natural Killer (NK) cells have a fundamental role in the control and immune surveillance of cancer development, progression and metastases. Notwithstanding the scarcity of studies to characterize NK cells in STS, it is noteworthy that the progression of these malignancies is associated with altered NK cells. These findings support the additional need to explore NK cell-based immunotherapy in STS; some clinical trials, although very tentatively, are already underway.

Abstract

Soft-tissue sarcomas (STS) represent about 80% of sarcomas, and are a heterogeneous group of rare and malignant tumors. STS arise from mesenchymal tissues and can grow into structures such as adipose tissue, muscles, nervous tissue and blood vessels. Morphological evaluation has been the standard model for the diagnosis of sarcomas, and even in samples with similar characteristics, they present a diversity in cytogenetic and genetic sequence alterations, which further increases the diversity of sarcomas. This variety is one of the main challenges for the classification and understanding of STS patterns, as well as for their respective treatments, which further decreases patient survival (<5 years). Despite some studies, little is known about the immunological profile of STS. As for the immunological profile of STS in relation to NK cells, there is also a shortage of studies. Observations made in solid tumors show that the infiltration of NK cells in tumors is associated with a good prognosis of the disease. Notwithstanding the scarcity of studies to characterize NK cells, their receptors, and ligands in STS, it is noteworthy that the progression of these malignancies is associated with altered NK phenotypes. Despite the scarcity of information on the function of NK cells, their phenotypes and their regulatory pathways in STS, the findings of this study support the additional need to explore NK cell-based immunotherapy in STS further. Some clinical trials, very tentatively, are already underway. STS clinical trials are still the basis for adoptive NK-cell and cytokine-based therapy.

Clinical, immunophenotypic and genomic findings of NK lymphoblastic leukemia: a study from the Bone Marrow Pathology Group

Natural killer (NK) cells are lymphocytes of the native immune system that play a pivotal role in host defense and immune surveillance. While the conceptual view of NK-neoplasms is evolving, little is known about the rare NK lymphoblastic leukemia (NK-LL), which remains as a provisional entity in the 2016 WHO Classification. The goal of this study is to characterize NK-LL cases and compare with other CD56 co-expressing acute leukemias. We identified 105 cases, diagnosed as NK-LL (6), CD56+ acute undifferentiated leukemia (AUL) (6), CD56+ T-lymphoblastic leukemia (T-LL) (51), and CD56+ acute myeloid leukemia (AML) (42). Compared to AUL patients, NK-LL patients were significantly younger (p = 0.021) and presented with higher white blood cell (WBC) (p = 0.037) and platelet counts (p = 0.041). Flow cytometry showed more frequent expression of cytoplasmic CD3 (cCD3, p = 0.064) and CD33, (p = 0.065), while HLA-DR was significantly absent from NK-LL (p = 0.035) compared to AUL. Compared to T-ALL, NK-LL cases showed less frequent cCD3 (p = 0.002), CD4 (p = 0.051), and CD10 expression (p = 0.06). The frequency of abnormal karyotypes was similar between NK-LL, AUL, and T-ALL. The mutational profile differed in four leukemia groups, with a significance enrichment of NOTCH1 (p = 0.002), ETV6 (p = 0.002) and JAK3 (p = 0.02) mutations in NK-LL as compared to AML. As compared to T-ALL, NK-LL cases showed a higher number of total mutations (p = 0.04) and significantly more frequent ETV6 mutations (p = 0.004). Clinical outcome data showed differences in overall survival between all four groups (p = 0.0175), but no difference in event free survival (p = 0.246). In this largest study to date, we find that that NK-LL shows clinical presentation, immunophenotypic and molecular characteristics distinct from AUL, T-ALL, and AML. Our findings suggest NK-LL is a distinct acute leukemia entity and should be considered in the clinical diagnosis of acute leukemias of ambiguous lineage.

Susceptibility of cyclin-dependent kinase inhibitor 1-deficient mice to rheumatoid arthritis arising from interleukin-1β-induced inflammation

We recently reported that cyclin-dependent kinase inhibitor 1 (p21) deficiency induces osteoarthritis susceptibility. Here, we determined the mechanism underlying the effect of p21 in synovial and cartilage tissues in RA. The knee joints of p21-knockout (p21^-/-) (n = 16) and wild type C57BL/6 (p21^+/+) mice (n = 16) served as in vivo models of collagen antibody-induced arthritis (CAIA). Arthritis severity was evaluated by immunological and histological analyses. The response of p21 small-interfering RNA (siRNA)-treated human RA FLSs (n = 5 per group) to interleukin (IL)-1β stimulation was determined in vitro. Arthritis scores were higher in p21^-/- mice than in p21^+/+ mice. More severe synovitis, earlier loss of Safranin-O staining, and cartilage destruction were observed in p21^-/- mice compared to p21^+/+ mice. p21^-/- mice expressed higher levels of IL-1β, TNF-α, F4/80, CD86, p-IKKα/β, and matrix metalloproteinases (MMPs) in cartilage and synovial tissues via IL-1β-induced NF-kB signaling. IL-1β stimulation significantly increased IL-6, IL-8, and MMP expression, and enhanced IKKα/β and IκBα phosphorylation in human FLSs. p21-deficient CAIA mice are susceptible to RA phenotype alterations, including joint cartilage destruction and severe synovitis. Therefore, p21 may have a regulatory role in inflammatory cytokine production including IL-1β, IL-6, and TNF-α.

Aerosol 1,25-dihydroxyvitamin D3 supplementation: A strategy to boost anti-tumor innate immune activity

BACKGROUND

1,25-dihydroxyvitamin D3 [1,25(OH)2D3] plays a role in calcium homeostasis but can also exert immunomodulatory effects. In lungs, characterized by a particular immunosuppressive environment primarily due to the presence of alveolar macrophages (AM), 1,25(OH)2D3 has been shown to favor the immune response against pathogens. Here, we explored the ability of aerosolized 1,25(OH)2D3 to locally promote an anti-tumor phenotype in alveolar macrophages (AM) in the treatment of lung metastases.

METHODS

Cytotoxicity assay has been used to assess the capability of AM, in vitro treated of not with 1,25(OH)2D3, to stimulate NK cells. Sulforhodamine B (SRB) assay has been used to assess the effect of 1,25(OH)2D3 on MC-38 and B16 tumor cells in vitro growth. 1,25(OH)2D3 was aerosolized in immunocompetent mouse models to evaluate the effect of local administration of 1,25(OH)2D3 on in vivo growth of MC-38 and B16 tumor cells within lungs and on infiltrating immune cells.

RESULTS

In vitro incubation of naïve AM with 1,25(OH)2D3 improved their ability to stimulate NK cell cytotoxicity. In vivo aerosolized 1,25(OH)2D3 significantly reduced the metastatic growth of MC-38 colon carcinoma, a tumor histotype that frequently metastasizes to lung in human. Immune infiltrate obtained from digested lungs of 1,25(OH)2D3-treated mice bearing MC-38 metastases revealed an increased expression of MHCII and CD80 on AM and an up-modulation of CD69 expression on effector cells that paralleled a strong increased ability of these cells to kill MC-38 tumor in vitro.

CONCLUSIONS

Together, these data show that aerosol delivery can represent a feasible and novel approach to supplement 1,25(OH)2D3 directly to the lungs promoting the activation of local immunity against cancer.

Chronic shift-lag promotes NK cell ageing and impairs immunosurveillance in mice by decreasing the expression of CD122

Long-term subjection to shift work increases the risk of cancer. The purpose of the present study was to explore the mechanism by which chronic circadian disruption impairs natural killer (NK) cell immunosurveillance. Mice were subjected to light-dark reverse every 4 days for 12 weeks to disrupt normal circadian rhythm. NK cell development and function were evaluated by flow cytometry. The mRNA and protein levels of period 1 (per1) and per2 were suppressed, while circadian locomotor output cycle kaput (CLOCK) was increased in the shifted mice, indicating successful generation of the circadian rhythm disruption mouse model. Chronic shift-lag promoted NK cell ageing, which is likely due to the reduction in Ly49 family receptor expression in shifted NK. We further studied the effects of circadian rhythm disruption on NK cell function. Chronic shift-lag inhibited NK cell secretion of granular CD107a and interferon gamma. Moreover, chronic shift-lag attenuated the clearance of MHC-I-deficient tumour cells by NK cells in vivo and promoted lung metastasis of B16F10 melanomas. Furthermore, chronic shift-lag reduced NK cell killing function, which may be due to the suppression of Eomes transcription factor expression, which inhibiting the transcription of CD122. In conclusion, our findings suggest that chronic circadian disruption attenuates NK cell cytolytic activity by decreasing the expression of CD122.

Escape of tumor cells from the NK cell cytotoxic activity

In recent years, NK cells, initially identified as potent cytotoxic effector cells, have revealed an unexpected complexity, both at phenotypic and functional levels. The discovery of different NK cell subsets, characterized by distinct gene expression and phenotypes, was combined with the characterization of the diverse functions NK cells can exert, not only as circulating cells, but also as cells localized or recruited in lymphoid organs and in multiple tissues. Besides the elimination of tumor and virus-infected cells, these functions include the production of cytokines and chemokines, the regulation of innate and adaptive immune cells, the influence on tissue homeostasis. In addition, NK cells display a remarkable functional plasticity, being able to adapt to the environment and to develop a kind of memory. Nevertheless, the powerful cytotoxic activity of NK cells remains one of their most relevant properties, particularly in the antitumor response. In this review, the process of tumor cell recognition and killing mediated by NK cells, starting from the generation of cytolytic granules and recognition of target cell, to the establishment of the NK cell immunological synapse, the release of cytotoxic molecules, and consequent tumor cell death is described. Next, the review focuses on the heterogeneous mechanisms, either intrinsic to tumors or induced by the tumor microenvironment, by which cancer cells can escape the NK cell-mediated attack.

Tumor microenvironment in primary liver tumors: A challenging role of natural killer cells

In the last years, several studies have been focused on elucidate the role of tumor microenvironment (TME) in cancer development and progression. Within TME, cells from adaptive and innate immune system are one of the main abundant components. The dynamic interactions between immune and cancer cells lead to the activation of complex molecular mechanisms that sustain tumor growth. This important cross-talk has been elucidate for several kind of tumors and occurs also in patients with liver cancer, such as hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Liver is well-known to be an important immunological organ with unique microenvironment. Here, in normal conditions, the rich immune-infiltrating cells cooperate with non-parenchymal cells, such as liver sinusoidal endothelial cells and Kupffer cells, favoring self-tolerance against gut antigens. The presence of underling liver immunosuppressive microenvironment highlights the importance to dissect the interaction between HCC and iCCA cells with immune infiltrating cells, in order to understand how this cross-talk promotes tumor growth. Deeper attention is, in fact, focused on immune-based therapy for these tumors, as promising approach to counteract the intrinsic anti-tumor activity of this microenvironment. In this review, we will examine the key pathways underlying TME cell-cell communications, with deeper focus on the role of natural killer cells in primary liver tumors, such as HCC and iCCA, as new opportunities for immune-based therapeutic strategies.

GCN2 drives macrophage and MDSC function and immunosuppression in the tumor microenvironment

General control nonderepressible 2 (GCN2) is an environmental sensor controlling transcription and translation in response to nutrient availability. Although GCN2 is a putative therapeutic target for immuno-oncology, its role in shaping the immune response to tumors is poorly understood. Here, we used mass cytometry, transcriptomics, and transcription factor-binding analysis to determine the functional impact of GCN2 on the myeloid phenotype and immune responses in melanoma. We found that myeloid-lineage deletion of GCN2 drives a shift in the phenotype of tumor-associated macrophages and myeloid-derived suppressor cells (MDSCs) that promotes antitumor immunity. Time-of-flight mass cytometry (CyTOF) and single-cell RNA sequencing showed that this was due to changes in the immune microenvironment with increased proinflammatory activation of macrophages and MDSCs and interferon-γ expression in intratumoral CD8⁺ T cells. Mechanistically, GCN2 altered myeloid function by promoting increased translation of the transcription factor CREB-2/ATF4, which was required for maturation and polarization of macrophages and MDSCs in both mice and humans, whereas targeting Atf4 by small interfering RNA knockdown reduced tumor growth. Last, analysis of patients with cutaneous melanoma showed that GCN2-dependent transcriptional signatures correlated with macrophage polarization, T cell infiltrates, and overall survival. Thus, these data reveal a previously unknown dependence of tumors on myeloid GCN2 signals for protection from immune attack.

Overview of Strategies to Improve Therapy against Tumors Using Natural Killer Cell

NK cells are lymphocytes with antitumor properties and can directly lyse tumor cells in a non-MHC-restricted manner. However, the tumor microenvironment affects the immune function of NK cells, which leads to immune evasion. This may be related to the pathogenesis of some diseases. Therefore, great efforts have been made to improve the immunotherapy effect of natural killer cells. NK cells from different sources can meet different clinical needs, in order to minimize the inhibition of NK cells and maximize the response potential of NK cells, for example, modification of NK cells can increase the number of NK cells in tumor target area, change the direction of NK cells, and improve their targeting ability to malignant cells. Checkpoint blocking is also a promising strategy for NK cells to kill tumor cells. Combination therapy is another strategy for improving antitumor ability, especially in combination with oncolytic viruses and nanomaterials. In this paper, the mechanisms affecting the activity of NK cells were reviewed, and the therapeutic potential of different basic NK cell strategies in tumor therapy was focused on. The main strategies for improving the immune function of NK cells were described, and some new strategies were proposed.

WNT Signaling in Tumors: The Way to Evade Drugs and Immunity

WNT/β-catenin signaling is involved in many physiological processes. Its implication in embryonic development, cell migration, and polarization has been shown. Nevertheless, alterations in this signaling have also been related with pathological events such as sustaining and proliferating the cancer stem cell (CSC) subset present in the tumor bulk. Related with this, WNT signaling has been associated with the maintenance, expansion, and epithelial-mesenchymal transition of stem cells, and furthermore with two distinctive features of this tumor population: therapeutic resistance (MDR, multidrug resistance) and immune escape. These mechanisms are developed and maintained by WNT activation through the transcriptional control of the genes involved in such processes. This review focuses on the description of the best known WNT pathways and the molecules involved in them. Special attention is given to the WNT cascade proteins deregulated in tumors, which have a decisive role in tumor survival. Some of these proteins function as extrusion pumps that, in the course of chemotherapy, expel the drugs from the cells; others help the tumoral cells hide from the immune effector mechanisms. Among the WNT targets involved in drug resistance, the drug extrusion pump MDR-1 (P-GP, ABCB1) and the cell adhesion molecules from the CD44 family are highlighted. The chemokine CCL4 and the immune checkpoint proteins CD47 and PD-L1 are included in the list of WNT target molecules with a role in immunity escape. This pathway should be a main target in cancer therapy as WNT signaling activation is essential for tumor progression and survival, even in the presence of the anti-tumoral immune response and/or antineoplastic drugs. The appropriate design and combination of anti-tumoral strategies, based on the modulation of WNT mediators and/or protein targets, could negatively affect the growth of tumoral cells, improving the efficacy of these types of therapies.

Innate Immune Responses in the Outcome of Haploidentical Hematopoietic Stem Cell Transplantation to Cure Hematologic Malignancies

In the context of allogeneic transplant platforms, human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) represents one of the latest and most promising curative strategies for patients affected by high-risk hematologic malignancies. Indeed, this platform ensures a suitable stem cell source immediately available for virtually any patents in need. Moreover, the establishment in recipients of a state of immunologic tolerance toward grafted hematopoietic stem cells (HSCs) remarkably improves the clinical outcome of this transplant procedure in terms of overall and disease free survival. However, the HLA-mismatch between donors and recipients has not been yet fully exploited in order to optimize the Graft vs. Leukemia effect. Furthermore, the efficacy of haplo-HSCT is currently hampered by several life-threatening side effects including the onset of Graft vs. Host Disease (GvHD) and the occurrence of opportunistic viral infections. In this context, the quality and the kinetic of the immune cell reconstitution (IR) certainly play a major role and several experimental efforts have been greatly endorsed to better understand and accelerate the post-transplant recovery of a fully competent immune system in haplo-HSCT. In particular, the IR of innate immune system is receiving a growing interest, as it recovers much earlier than T and B cells and it is able to rapidly exert protective effects against both tumor relapses, GvHD and the onset of life-threatening opportunistic infections. Herein, we review our current knowledge in regard to the kinetic and clinical impact of Natural Killer (NK), γδ and Innate lymphoid cells (ILCs) IRs in both allogeneic and haplo-HSCT. The present paper also provides an overview of those new therapeutic strategies currently being implemented to boost the alloreactivity of the above-mentioned innate immune effectors in order to ameliorate the prognosis of patients affected by hematologic malignancies and undergone transplant procedures.

On the Way to Become a Natural Killer Cell

Natural Killer (NK) cells are innate lymphocytes playing pivotal roles in host defense and immune-surveillance. The homeostatic modulation of germ-line encoded/non-rearranged activating and inhibitory NK cell receptors (NKRs) determines the capability of these innate lymphocytes to either spare "self" cells or to kill viral-infected, tumor-transformed and heterologous cell targets. However, despite being discovered more than 40 years ago, several aspects of NK cell biology remain unknown or are still being debated. In particular, our knowledge of human NK cell ontogenesis and differentiation is still in its infancy as the majority of our experimental evidence on this topic mainly comes from findings obtained in vitro or with animal models in vivo. Although both the generation and the maintenance of human NK cells are sustained by hematopoietic stem cells (HSCs), the precise site(s) of NK cell development are still poorly defined. Indeed, HSCs and hematopoietic precursors are localized in different anatomical compartments that also change their ontogenic commitments before and after birth as well as in aging. Currently, the main site of NK cell generation and maturation in adulthood is considered the bone marrow, where their interactions with stromal cells, cytokines, growth factors, and other soluble molecules support and drive maturation. Different sequential stages of NK cell development have been identified on the basis of the differential expression of specific markers and NKRs as well as on the acquisition of specific effector-functions. All these phenotypic and functional features are key in inducing and regulating homing, activation and tissue-residency of NK cells in different human anatomic sites, where different homeostatic mechanisms ensure a perfect balance between immune tolerance and immune-surveillance. The present review summarizes our current knowledge on human NK cell ontogenesis and on the related pathways orchestrating a proper maturation, functions, and distributions.

The macrophage tetraspan MS4A4A enhances dectin-1-dependent NK cell-mediated resistance to metastasis

The plasma membrane tetraspan molecule MS4A4A is selectively expressed by macrophage-lineage cells, but its function is unknown. Here we report that MS4A4A was restricted to murine and human mononuclear phagocytes and was induced during monocyte-to-macrophage differentiation in the presence of interleukin 4 or dexamethasone. Human MS4A4A was co-expressed with M2/M2-like molecules in subsets of normal tissue-resident macrophages, infiltrating macrophages from inflamed synovium and tumor-associated macrophages. MS4A4A interacted and colocalized with the β-glucan receptor dectin-1 in lipid rafts. In response to dectin-1 ligands, Ms4a4a-deficient macrophages showed defective signaling and defective production of effector molecules. In experimental models of tumor progression and metastasis, Ms4a4a deficiency in macrophages had no impact on primary tumor growth, but was essential for dectin-1-mediated activation of macrophages and natural killer (NK) cell-mediated metastasis control. Thus, MS4A4A is a tetraspan molecule selectively expressed in macrophages during differentiation and polarization, essential for dectin-1-dependent activation of NK cell-mediated resistance to metastasis.

An Historical Overview: The Discovery of How NK Cells Can Kill Enemies, Recruit Defense Troops, and More

Natural killer (NK) cells were originally defined as effector lymphocytes of innate immunity characterized by the unique ability of killing tumor and virally infected cells without any prior priming and expansion of specific clones. The "missing-self" theory, proposed by Klas Karre, the seminal discovery of the first prototypic HLA class I-specific inhibitory receptors, and, later, of the Natural Cytotoxicity Receptors (NCRs) by Alessandro Moretta, provided the bases to understand the puzzling behavior of NK cells. Actually, those discoveries proved crucial also for many of the achievements that, along the years, have contributed to the modern view of these cells. Indeed, NK cells, besides killing susceptible targets, are now known to functionally interact with different immune cells, sense pathogens using TLR, adapt their responses to the local environment, and, even, mount a sort of immunological memory. In this review, we will specifically focus on the main activating NK receptors and on their crucial role in the ever-increasing number of functions assigned to NK cells and other innate lymphoid cells (ILCs).

Generation of monocyte-derived tumor-associated macrophages using tumor-conditioned media provides a novel method to study tumor-associated macrophages in vitro

Background

Tumor-associated macrophages (TAM) are expanded and exhibit tumor-promoting properties within the tumor microenvironment. Current methods to study TAM have not been replicated across cancer types and often do not include exogenous growth factors from the tumor, a key factor in TAM differentiation in vivo.

Methods

In this study, an in vitro method to generate monocyte- derived TAM using tumor- conditioned media (TCM) and a cytokine cocktail containing IL-4, IL-10, and M-CSF was utilized to study the phenotype, morphology, and function of TAM across multiple cancer types. TCM was generated from two breast cancer cell lines and an Epstein-Barr virus-positive lymphoma cell line. The properties of in vitro generated TAM were compared to in vitro generated M1 and M2- like macrophages and TAM isolated from patients with cancer.

Results

TAM generated in this fashion displayed an increase in CD163/CD206 co-expression compared to M2- like macrophages (87 and 36%, respectively). TAM generated in vitro exhibited increased transcript levels of the functional markers IL-6, IL-10, CCL2, c-Myc, iNOS, and arginase compared to in vitro generated M2-like macrophages. Functionally, in vitro generated TAM inhibited the proliferation of T cells (47% decrease from M1-like macrophages) and the production of IFN-γ by natural killer cells was inhibited (44%) when co-cultured with TAM. Furthermore, in vitro generated TAM secreted soluble factors that promote the growth and survival of tumor cells.

Conclusions

Limited access to patient TAM highlights the need for methods to generate TAM in vitro. Our data confirm that monocyte-derived TAM can be generated reliably using TCM plus the cytokine cocktail of IL-4, IL-10, and M-CSF. Given the ability of TAM to inhibit immune cell function, continued study of methods to deplete or deactivate TAM in the setting of cancer are warranted.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0622-0) contains supplementary material, which is available to authorized users.

The Natural Cytotoxicity Receptors in Health and Disease

The Natural Cytotoxicity Receptors (NCRs), NKp46, NKp44, and NKp30, were some of the first human activating Natural Killer (NK) cell receptors involved in the non-MHC-restricted recognition of tumor cells to be cloned over 20 years ago. Since this time many host- and pathogen-encoded ligands have been proposed to bind the NCRs and regulate the cytotoxic and cytokine-secreting functions of tissue NK cells. This diverse set of NCR ligands can manifest on the surface of tumor or virus-infected cells or can be secreted extracellularly, suggesting a remarkable NCR polyfunctionality that regulates the activity of NK cells in different tissue compartments during steady state or inflammation. Moreover, the NCRs can also be expressed by other innate and adaptive immune cell subsets under certain tissue conditions potentially conferring NK recognition programs to these cells. Here we review NCR biology in health and disease with particular reference to how this important class of receptors regulates the functions of tissue NK cells as well as confer NK cell recognition patterns to other innate and adaptive lymphocyte subsets. Finally, we highlight how NCR biology is being harnessed for novel therapeutic interventions particularly for enhanced tumor surveillance.

Natural Killer Cells as Key Players of Tumor Progression and Angiogenesis: Old and Novel Tools to Divert Their Pro-Tumor Activities into Potent Anti-Tumor Effects

Immune cells, as a consequence of their plasticity, can acquire altered phenotype/functions within the tumor microenvironment (TME). Some of these aberrant functions include attenuation of targeting and killing of tumor cells, tolerogenic/immunosuppressive behavior and acquisition of pro-angiogenic activities. Natural killer (NK) cells are effector lymphocytes involved in tumor immunosurveillance. In solid malignancies, tumor-associated NK cells (TANK cells) in peripheral blood and tumor-infiltrating NK (TINK) cells show altered phenotypes and are characterized by either anergy or reduced cytotoxicity. Here, we aim at discussing how NK cells can support tumor progression and how induction of angiogenesis, due to TME stimuli, can be a relevant part on the NK cell-associated tumor supporting activities. We will review and discuss the contribution of the TME in shaping NK cell response favoring cancer progression. We will focus on TME-derived set of factors such as TGF-β, soluble HLA-G, prostaglandin E₂, adenosine, extracellular vesicles, and miRNAs, which can exhibit a dual function. On one hand, these factors can suppress NK cell-mediated activities but, on the other hand, they can induce a pro-angiogenic polarization in NK cells. Also, we will analyze the impact on cancer progression of the interaction of NK cells with several TME-associated cells, including macrophages, neutrophils, mast cells, cancer-associated fibroblasts, and endothelial cells. Then, we will discuss the most relevant therapeutic approaches aimed at potentiating/restoring NK cell activities against tumors. Finally, supported by the literature revision and our new findings on NK cell pro-angiogenic activities, we uphold NK cells to a key host cellular paradigm in controlling tumor progression and angiogenesis; thus, we should bear in mind NK cells like a TME-associated target for anti-tumor therapeutic approaches.

Targeting NKG2A to elucidate natural killer cell ontogenesis and to develop novel immune-therapeutic strategies in cancer therapy

Natural Killer (NK) cells are innate immune cells with a primary role in the immune surveillance against non-self-cells. NK cell recognition of "self" relies on the surface expression on autologous cells of MHC class I (MHC-I) molecules. Either the absence or the down-modulation of MHC-I on target cells "license" NK cells to kill threatening tumor-transformed or virally infected cells. This phenomenon is controlled by a limited repertoire of activating and inhibitory NK receptors (aNKRs and iNKRs) that tunes NK cell activation and effector functions. Hence, the calibration of NK cell alloreactivity depends on the ability of iNKRs to bind MHC-I complex and these interactions are key in regulating both NK cell differentiation and effector functions. Indeed, the presence of iNKRs specific for self-MHC haplotypes (i) plays a role in the "licensing/education" process that controls the responsiveness of mature NK cells and prevents their activation against the "self" and (ii) is exploited by tumor cells to escape from NK cell cytotoxicity. Herein, we review our current knowledge on function and clinical application of NKG2A, a C-type lectin iNKR that binds specific haplotypes of human leukocyte antigens early during the NK cell maturation process, thus contributing to modulate the terminal maturation of NK cells as potent effectors against cancers cells. These NKG2A-mediated mechanisms are currently being exploited for developing promising immune-therapeutic strategies to improve the prognosis of solid and blood tumors and to ameliorate the clinical outcome of patients undergone allogeneic hematopoietic stem cell transplantation to treat high-risk hematologic malignancies.

Nature of coexisting thyroid autoimmune disease determines success or failure of tumor immunity in thyroid cancer

Background

Thyroid cancer and thyroid autoimmunity are considered opposite extremes of immune-responses. However, several studies have suggested that thyroid cancer coexists with autoimmune thyroid diseases like Hashimoto Thyroiditis (HT) and Graves disease (GD). We have shown that the risk of developing thyroid cancer is higher in patients with a silent form of autoimmune thyroid disease -Euthyroid Hashimoto Thyroiditis-(EHT).

Methods

We analyzed data from 2633 consecutive patients with GD, HT, EHT and non-Autoimmune Thyroid Disease (Non-AITD) for the presence of Differentiated Thyroid Cancer (DTC). We further investigated the microenvironment, and cellular mechanism of protection from DTC in GD/EHT by ex-vivo aspirating infiltrates from thyroid samples. We also re-constituted in vitro the in-vivo microenvironment to mimic an in-vivo context. We isolated NK cells and differentiated macrophages into M1 and M2 phenotype from healthy human peripheral blood monocytes.

Results

DTC was less frequent/aggressive in GD as compared to EHT or Non-AITD. Intra-thyroidal immune-cell profiling revealed differential Natural Killer (NK) cell activity and macrophage polarization in the settings of GD versus EHT. In GD, NK-cells were activated, and macrophages showed M1-like phenotype whereas, in EHT, NK-cells were less active and macrophages displayed M2-like phenotype. Furthermore, in vitro co-cultures of NK-cells with differentiated macrophage subsets revealed that the presence of activated NK (NA) cells favors M1 macrophages, boosts macrophage action and amplifies the innate defense mechanisms. Moreover, co-culture of M2 macrophages with NA, increases the cytotoxicity of NK-cells and favors a pro-inflammatory microenvironment that reverts the anti-inflammatory M2 towards pro-inflammatory M1.

Conclusion

Surveillance innate immune-cells like Natural Killer (NK) cells and macrophages are complementary to each other in their actions. We discovered here that activated NK-cells in the background of the thyroid autoimmune disease, GD, drive macrophage differentiation to the M1/killer phenotype which in turn is cytotoxic to cancer cells and down regulates the M2/repair phenotype. Understanding the molecular basis of macrophage-NK cell interface in Thyroid Cancer, ETH and GD will open new vistas for immunopathology and therapeutic intervention. Macrophages/innate immunity can be modulated from M2 to M1 phenotype to help treat thyroid cancer as naturally done by GD.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0483-y) contains supplementary material, which is available to authorized users.

NK cell recruitment in salivary glands provides early viral control but is dispensable for tertiary lymphoid structure formation

Salivary glands (SGs) represent a permissive site for several sialotropic viruses whose persistence is linked to the development of autoimmunity. Natural Killer (NK) cells play a key role in viral clearance but their involvement in viral infection control and in tertiary lymphoid structures (TLS) development within SGs is unknown. By using an inducible model of TLS in the SGs of wild-type C57BL/6 mice, induced by the local delivery of a replication-defective adenovirus (AdV), we demonstrated that circulating NK cells are rapidly recruited to SGs and highly enrich the early inflammatory infiltrate prior to TLS development. NK cells migrating to SGs in response to AdV infection up-regulate NKp46, undergo proliferation, acquire cytotoxic potential, produce Granzyme-B and IFN-γ, and reduce viral load in the acute phase of the infection. Nonetheless, the selective depletion of both circulating and infiltrating NK cells in AdV-infected mice neither affect the development and frequency of TLS nor the onset of autoimmunity. These data demonstrate that, upon local viral delivery of AdV, peripheral NK cells homing to SGs can exert an early control of the viral infection but are dispensable for the formation of TLS and breach of immunologic tolerance.