Invariant NKT cells: regulation and function during viral infection

Dysfunctional states of unconventional T-cell subsets in cancer

Unconventional T cells represent a promising therapeutic agent to overcome the current limitations of immunotherapies due to their universal T-cell receptors, ability to respond directly to cytokine stimulation, and capacity to recruit and modulate conventional immune cells in the tumor microenvironment. Like conventional T cells, unconventional T cells can enter a dysfunctional state, and the functional differences associated with this state may provide insight into the discrepancies observed in their role in antitumor immunity in various cancers. The exhaustive signature of unconventional T cells differs from conventional αβ T cells, and understanding the differences in the mechanisms underlying exhaustive differentiation in these cell types may aid in the discovery of new treatments to improve sustained antitumor responses. Ongoing clinical trials investigating therapies that leverage unconventional T-cell populations have shown success in treating hematologic malignancies and reducing the immunosuppressive tumor environment. However, several hurdles remain to extend these promising results into solid tumors. Here we discuss the current knowledge on unconventional T-cell function/dysfunction and consider how the incorporation of therapies that modulate unconventional T-cell exhaustion may aid in overcoming the current limitations of immunotherapy. Additionally, we discuss how components of the tumor microenvironment alter the functions of unconventional T cells and how these changes can affect tumor infiltration by lymphocytes and alter conventional T-cell responses.

Diversification of a Novel α-Galactosyl Ceramide Hotspot Boosts the Adjuvant Properties in Parenteral and Mucosal Vaccines

The development of potent adjuvants is an important step for improving the performance of subunit vaccines. CD1d agonists, such as the prototypical α-galactosyl ceramide (α-GalCer), are of special interest due to their ability to activate iNKT cells and trigger rapid dendritic cell maturation and B-cell activation. Herein, we introduce a novel derivatization hotspot at the α-GalCer skeleton, namely the N-substituent at the amide bond. The multicomponent diversification of this previously unexplored glycolipid chemotype space permitted the introduction of a variety of extra functionalities that can either potentiate the adjuvant properties or serve as handles for further conjugation to antigens toward the development of self-adjuvanting vaccines. This strategy led to the discovery of compounds eliciting enhanced antigen-specific T cell stimulation and a higher antibody response when delivered by either the parenteral or the mucosal route, as compared to a known potent CD1d agonist. Notably, various functionalized α-GalCer analogues showed a more potent adjuvant effect after intranasal immunization than a PEGylated α-GalCer analogue previously optimized for this purpose. Ultimately, this work could open multiple avenues of opportunity for the use of mucosal vaccines against microbial infections.

HIVEP3 inhibits fate decision of CD8+ invariant NKT cells after positive selection

CD8+ invariant natural killer T (iNKT) cells are functionally different from other iNKT cells and are enriched in human but not in mouse. To date, their developmental pathway and molecular basis for fate decision remain unclear. Here, we report enrichment of CD8+ iNKT cells in neonatal mice due to their more rapid maturation kinetics than CD8- iNKT cells. Along developmental trajectories, CD8+ and CD8- iNKT cells separate at stage 0, following stage 0 double-positive iNKT cells, and differ in HIVEP3 expression. HIVEP3 is lowly expressed in stage 0 CD8+ iNKT cells and negatively controls their development, whereas it is highly expressed in stage 0 CD8- iNKT cells and positively controls their development. Despite no effect on IFN-γ, HIVEP3 inhibits granzyme B but promotes interleukin-4 production in CD8+ iNKT cells. Together, we reveal that, as a negative regulator for CD8+ iNKT fate decision, low expression of HIVEP3 in stage 0 CD8+ iNKT cells favors their development and T helper 1-biased cytokine responses as well as high cytotoxicity.

SARS-CoV-2 Omicron (B.1.1.529) shows minimal neurotropism in a double-humanized mouse model

Although severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) initially infects the respiratory tract, it also directly or indirectly affects other organs, including the brain. However, little is known about the relative neurotropism of SARS-CoV-2 variants of concern (VOCs), including Omicron (B.1.1.529), which emerged in November 2021 and has remained the dominant pathogenic lineage since then. To address this gap, we examined the relative ability of Omicron, Beta (B.1.351), and Delta (B.1.617.2) to infect the brain in the context of a functional human immune system by using human angiotensin-converting enzyme 2 (hACE2) knock-in triple-immunodeficient NGC mice with or without reconstitution with human CD34+ stem cells. Intranasal inoculation of huCD34+-hACE2-NCG mice with Beta and Delta resulted in productive infection of the nasal cavity, lungs, and brain on day 3 post-infection, but Omicron was surprisingly unique in its failure to infect either the nasal tissue or brain. Moreover, the same infection pattern was observed in hACE2-NCG mice, indicating that antiviral immunity was not responsible for the lack of Omicron neurotropism. In independent experiments, we demonstrate that nasal inoculation with Beta or with D614G, an ancestral SARS-CoV-2 with undetectable replication in huCD34+-hACE2-NCG mice, resulted in a robust response by human innate immune cells, T cells, and B cells, confirming that exposure to SARS-CoV-2, even without detectable infection, is sufficient to induce an antiviral immune response. Collectively, these results suggest that modeling of the neurologic and immunologic sequelae of SARS-CoV-2 infection requires careful selection of the appropriate SARS-CoV-2 strain in the context of a specific mouse model.

Potent NKT cell ligands overcome SARS-CoV-2 immune evasion to mitigate viral pathogenesis in mouse models

One of the major pathogenesis mechanisms of SARS-CoV-2 is its potent suppression of innate immunity, including blocking the production of type I interferons. However, it is unknown whether and how the virus interacts with different innate-like T cells, including NKT, MAIT and γδ T cells. Here we reported that upon SARS-CoV-2 infection, invariant NKT (iNKT) cells rapidly trafficked to infected lung tissues from the periphery. We discovered that the envelope (E) protein of SARS-CoV-2 efficiently down-regulated the cell surface expression of the antigen-presenting molecule, CD1d, to suppress the function of iNKT cells. E protein is a small membrane protein and a viroporin that plays important roles in virion packaging and envelopment during viral morphogenesis. We showed that the transmembrane domain of E protein was responsible for suppressing CD1d expression by specifically reducing the level of mature, post-ER forms of CD1d, suggesting that it suppressed the trafficking of CD1d proteins and led to their degradation. Point mutations demonstrated that the putative ion channel function was required for suppression of CD1d expression and inhibition of the ion channel function using small chemicals rescued the CD1d expression. Importantly, we discovered that among seven human coronaviruses, only E proteins from highly pathogenic coronaviruses including SARS-CoV-2, SARS-CoV and MERS suppressed CD1d expression, whereas the E proteins of human common cold coronaviruses, HCoV-OC43, HCoV-229E, HCoV-NL63 and HCoV-HKU1, did not. These results suggested that E protein-mediated evasion of NKT cell function was likely an important pathogenesis factor, enhancing the virulence of these highly pathogenic coronaviruses. Remarkably, activation of iNKT cells with their glycolipid ligands, both prophylactically and therapeutically, overcame the putative viral immune evasion, significantly mitigated viral pathogenesis and improved host survival in mice. Our results suggested a novel NKT cell-based anti-SARS-CoV-2 therapeutic approach.

Current Developments in the Preclinical and Clinical use of Natural Killer T cells

Natural killer T (NKT) cells play a pivotal role as a bridge between the innate and the adaptive immune response and are instrumental in the regulation of homeostasis. In this review, we discuss the potential for NKT cells to serve as biodrugs in viral infections and in cancer. NKT cells are being investigated for their use as a prognostic biomarker, an immune adjuvant, and as a form of cellular therapy. Historically, the clinical utility of NKT cells was hampered by their low frequency in the blood, discrepancies in nomenclature, and challenges with ex vivo expansion. However, recent advances in the field have permitted the development of several NKT cell-based preclinical and clinical strategies. These new developments pave the way for the successful implementation of NKT cell-based approaches for the treatment of human disease.

Antiviral activity of glucosylceramide synthase inhibitors in alphavirus infection of the central nervous system

Virus-induced CNS diseases impose a considerable human health burden worldwide. For many viral CNS infections, neither antiviral drugs nor vaccines are available. In this study, we examined whether the synthesis of glycosphingolipids, major membrane lipid constituents, could be used to establish an antiviral therapeutic target. We found that neuroinvasive Sindbis virus altered the sphingolipid levels early after infection in vitro and increased the levels of gangliosides GA1 and GM1 in the sera of infected mice. The alteration in the sphingolipid levels appears to play a role in neuroinvasive Sindbis virus replication, as treating infected cells with UDP-glucose ceramide glucosyltransferase (UGCG) inhibitors reduced the replication rate. Moreover, the UGCG inhibitor GZ-161 increased the survival rates of Sindbis-infected mice, most likely by reducing the detrimental immune response activated by sphingolipids in the brains of Sindbis virus-infected mice. These findings suggest a role for glycosphingolipids in the host immune response against neuroinvasive Sindbis virus and suggest that UGCG inhibitors should be further examined as antiviral therapeutics for viral infections of the CNS.

Demonstration of the Antitumor Activity of the iNKT Agonist ABX196, a Novel Enhancer of Cancer Immunotherapy, in Melanoma and Hepatocarcinoma Mouse Models

Immune checkpoint blockers (ICB) provide a promising approach to antitumor immunotherapy through blockade of immunosuppressive pathways. The synthetic glycolipid, ABX196, is a potent stimulator of invariant natural killer T cells (iNKT), a small subset of regulatory lymphocytes, which are powerful enhancers of immunity when activated. ABX196 was investigated alone and in combination with chemotherapy and ICBs in a melanoma B16F10 tumor cell-bearing and an orthotopic Hepa 1-6 hepatocarcinoma (HCC) cell-bearing C57BL/6 mice model. In the melanoma model, immune response evaluation included immunofluorescence staining and detection by flow cytometry to identify anti-CD45, anti-CD8, anti-CD4, anti-CD3, anti-CD19, anti-FoxP3, CD1d tetramer, and anti-programmed cell death protein 1 (PD-1) markers. Analysis by MRI, liver weight, and IHC staining to detect CD4, CD8, F4/80, PD-1, programmed death-ligand 1, Ki67, and FoxP3 markers were used to measure antitumor response in the HCC model. Combination treatment with ABX196 and anti-PD-1 resulted in significant synergistic antitumor effects, reflected by the increase of CD8+ cells in the tumor and an increased ratio of CD8+ effector cells to FoxP3+ regulatory T cells (Treg) in mice with melanomas. ABX196 monotherapy and combination therapy resulted in antitumor effects in the HCC model. No significant differences in survival were demonstrated between monotherapy and combination therapy due to high response levels with either treatment. A synergistic combination effect was apparent when IFNγ was measured in peripheral blood, indicating sustained activation of iNKT cells. In both models, the antitumor effects were associated with a generation of a more advantageous T-effector to Treg cell ratio within the tumor, which could lead to in the proliferation and accumulation of cells that would otherwise be anergized.

SYNOPSIS

Using melanoma and HCC tumor models in mice, this study demonstrates the potential of ABX196, alone and in combination with anti-PD-1 antibody, as a novel strategy to overcome the immunosuppressive microenvironment and to produce antitumor activity.

Autoimmune disorders associated with common variable immunodeficiency: prediction, diagnosis, and treatment

INTRODUCTION

Common variable immunodeficiency (CVID) is the most common symptomatic primary immunodeficiency. Due to the wide spectrum of the CVID manifestations, the differential diagnosis becomes complicated, ends in a diagnostic delay and increased morbidity and mortality rates. Autoimmunity is one of the important complications associated with CVID. While immunoglobulin replacement therapy has considerably decreased the mortality rate in CVID patients, mainly infection-related mortality, other complications such as autoimmunity appeared prevalent and, in some cases, life threatening.

AREAS COVERED

In this article, genetics, responsible immune defects, autoimmune manifestations in different organs, and the diagnosis and treatment processes in CVID patients are reviewed, after searching the literature about these topics.

EXPERT OPINION

Considering the many phenotypes of CVID and the fact that it remained undiagnosed until older ages, it is important to include various manifestations of CVID in the differential diagnosis. Due to the different manifestations of CVID, including autoimmune diseases, interdisciplinary collaboration of physicians from different fields is highly recommended, as discussed in the manuscript. Meanwhile, it is important to determine which patients could benefit from genetic diagnostic studies since such studies are not necessary for establishing the diagnosis of CVID.

Target tumor microenvironment by innate T cells

The immunosuppressive tumor microenvironment (TME) remains one of the most prevailing barriers obstructing the implementation of effective immunotherapy against solid-state cancers. Eminently composed of immunosuppressive tumor associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) among others, the TME attenuates the effects of immune checkpoint blockade and adoptive cell therapies, mandating a novel therapy capable of TME remediation. In this review we explore the potential of three innate-like T cell subsets, invariant natural killer T (iNKT), mucosal-associated invariant T (MAIT) cells, and gamma delta T (γδT) cells, that display an intrinsic anti-TAM/MDSC capacity. Exhibiting both innate and adaptive properties, innate-like T cell types express a subset-specific TCR with distinct recombination, morphology, and target cell recognition, further supplemented by a variety of NK activating receptors. Both NK activating receptor and TCR activation result in effector cell cytotoxicity against targeted immunosuppressive cells for TME remediation. In addition, innate-like T cells showcase moderate levels of tumor cell killing, providing dual antitumor and anti-TAM/MDSC function. This latent antitumor capacity can be further bolstered by chimeric antigen receptor (CAR) engineering for recognition of tumor specific antigens to enhance antitumor targeting. In contrast with established CAR-T cell therapies, adoption of these innate-like cell types provides an enhanced safety profile without the risk of graft versus host disease (GvHD), due to their non-recognition of mismatched major histocompatibility complex (MHC) molecules, for use as widely accessible, allogeneic “off-the-shelf” cancer immunotherapy.

METTL14-dependent m6A modification controls iNKT cell development and function

N⁶-methyladenosine (m⁶A), the most common form of RNA modification, controls CD4⁺ T cell homeostasis by targeting the IL-7/STAT5/SOCS signaling pathways. The role of m⁶A modification in unconventional T cell development remains unknown. Using mice with T cell-specific deletion of RNA methyltransferase METTL14 (T-Mettl14^−/−), we demonstrate that m⁶A modification is indispensable for iNKT cell homeostasis. Loss of METTL14-dependent m⁶A modification leads to the upregulation of apoptosis in double-positive thymocytes, which in turn decreases Vα14-Jα18 gene rearrangements, resulting in drastic reduction of iNKT numbers in the thymus and periphery. Residual T-Mettl14^−/− iNKT cells exhibit increased apoptosis, impaired maturation, and decreased responsiveness to IL-2/IL-15 and TCR stimulation. Furthermore, METTL14 knockdown in mature iNKT cells diminishes their cytokine production, correlating with increased Cish expression and decreased TCR signaling. Collectively, our study highlights a critical role for METTL14-dependent-m⁶A modification in iNKT cell development and function.

Cao et al. show that T cell-specific deletion of METTL14, a component of RNA m⁶A writer complex, leads to severe defects in iNKT cell development, survival, and function. Mechanistically, METTL14-dependent m⁶A modification controls iNKT cell development in a cell-intrinsic manner by regulating the apoptosis pathway and TCR signaling pathway.

Development of off-the-shelf hematopoietic stem cell-engineered invariant natural killer T cells for COVID-19 therapeutic intervention

BACKGROUND

New COVID-19 treatments are desperately needed as case numbers continue to rise and emergent strains threaten vaccine efficacy. Cell therapy has revolutionized cancer treatment and holds much promise in combatting infectious disease, including COVID-19. Invariant natural killer T (iNKT) cells are a rare subset of T cells with potent antiviral and immunoregulatory functions and an excellent safety profile. Current iNKT cell strategies are hindered by the extremely low presence of iNKT cells, and we have developed a platform to overcome this critical limitation.

METHODS

We produced allogeneic HSC-engineered iNKT (AlloHSC-iNKT) cells through TCR engineering of human cord blood CD34+ hematopoietic stem cells (HSCs) and differentiation of these HSCs into iNKT cells in an Ex Vivo HSC-Derived iNKT Cell Culture. We then established in vitro SARS-CoV-2 infection assays to assess AlloHSC-iNKT cell antiviral and anti-hyperinflammation functions. Lastly, using in vitro and in vivo preclinical models, we evaluated AlloHSC-iNKT cell safety and immunogenicity for off-the-shelf application.

RESULTS

We reliably generated AlloHSC-iNKT cells at high-yield and of high-purity; these resulting cells closely resembled endogenous human iNKT cells in phenotypes and functionalities. In cell culture, AlloHSC-iNKT cells directly killed SARS-CoV-2 infected cells and also selectively eliminated SARS-CoV-2 infection-stimulated inflammatory monocytes. In an in vitro mixed lymphocyte reaction (MLR) assay and an NSG mouse xenograft model, AlloHSC-iNKT cells were resistant to T cell-mediated alloreaction and did not cause GvHD.

CONCLUSIONS

Here, we report a method to robustly produce therapeutic levels of AlloHSC-iNKT cells. Preclinical studies showed that these AlloHSC-iNKT cells closely resembled endogenous human iNKT cells, could reduce SARS-CoV-2 virus infection load and mitigate virus infection-induced hyperinflammation, and meanwhile were free of GvHD-risk and resistant to T cell-mediated allorejection. These results support the development of AlloHSC-iNKT cells as a promising off-the-shelf cell product for treating COVID-19; such a cell product has the potential to target the new emerging SARS-CoV-2 variants as well as the future new emerging viruses.

Ingestion, Immunity, and Infection: Nutrition and Viral Respiratory Tract Infections

Respiratory infections place a heavy burden on the health care system, particularly in the winter months. Individuals with a vulnerable immune system, such as very young children and the elderly, and those with an immune deficiency, are at increased risk of contracting a respiratory infection. Most respiratory infections are relatively mild and affect the upper respiratory tract only, but other infections can be more serious. These can lead to pneumonia and be life-threatening in vulnerable groups. Rather than focus entirely on treating the symptoms of infectious disease, optimizing immune responsiveness to the pathogens causing these infections may help steer towards a more favorable outcome. Nutrition may have a role in such prevention through different immune supporting mechanisms. Nutrition contributes to the normal functioning of the immune system, with various nutrients acting as energy sources and building blocks during the immune response. Many micronutrients (vitamins and minerals) act as regulators of molecular responses of immune cells to infection. It is well described that chronic undernutrition as well as specific micronutrient deficiencies impair many aspects of the immune response and make individuals more susceptible to infectious diseases, especially in the respiratory and gastrointestinal tracts. In addition, other dietary components such as proteins, pre-, pro- and synbiotics, and also animal- and plant-derived bioactive components can further support the immune system. Both the innate and adaptive defense systems contribute to active antiviral respiratory tract immunity. The initial response to viral airway infections is through recognition by the innate immune system of viral components leading to activation of adaptive immune cells in the form of cytotoxic T cells, the production of neutralizing antibodies and the induction of memory T and B cell responses. The aim of this review is to describe the effects of a range different dietary components on anti-infective innate as well as adaptive immune responses and to propose mechanisms by which they may interact with the immune system in the respiratory tract.

Exploring the Role of Innate Lymphocytes in the Immune System of Bats and Virus-Host Interactions

Bats are reservoirs of a large number of viruses of global public health significance, including the ancestral virus for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the causative agent of coronavirus disease 2019 (COVID-19). Although bats are natural carriers of multiple pathogenic viruses, they rarely display signs of disease. Recent insights suggest that bats have a more balanced host defense and tolerance system to viral infections that may be linked to the evolutionary adaptation to powered flight. Therefore, a deeper understanding of bat immune system may provide intervention strategies to prevent zoonotic disease transmission and to identify new therapeutic targets. Similar to other eutherian mammals, bats have both innate and adaptive immune systems that have evolved to detect and respond to invading pathogens. Bridging these two systems are innate lymphocytes, which are highly abundant within circulation and barrier tissues. These cells share the characteristics of both innate and adaptive immune cells and are poised to mount rapid effector responses. They are ideally suited as the first line of defense against early stages of viral infections. Here, we will focus on the current knowledge of innate lymphocytes in bats, their function, and their potential role in host–pathogen interactions. Moreover, given that studies into bat immune systems are often hindered by a lack of bat-specific research tools, we will discuss strategies that may aid future research in bat immunity, including the potential use of organoid models to delineate the interplay between innate lymphocytes, bat viruses, and host tolerance.

Peripheral blood iNKT cell activation correlates with liver damage during acute hepatitis C

Invariant NK T (iNKT) cells are implicated in viral clearance; however, their role in hepatitis C virus (HCV) infection remains controversial. Here, iNKT cells were studied during different stages of HCV infection. iNKT cells from patients with acute HCV infection and people who inject drugs (PWID) with chronic or spontaneously resolved HCV infection were characterized by flow cytometry. In a longitudinal analysis during acute HCV infection, frequencies of activated CD38⁺ iNKT cells reproducibly declined in spontaneously resolving patients, whereas they were persistently elevated in patients progressing to chronic infection. During the first year of infection, the frequency of activated CD38⁺ or CD69⁺ iNKT cells strongly correlated with alanine transaminase levels with particularly pronounced correlations in spontaneously resolving patients. Increased frequencies of activated iNKT cells in chronic HCV infection were confirmed in cross-sectional analyses of PWID with chronic or spontaneously resolved HCV infection; however, no apparent functional differences were observed with various stimulation protocols. Our data suggest that iNKT cells are activated during acute hepatitis C and that activation is sustained in chronic infection. The correlation between the frequency of activated iNKT cells and alanine transaminase may point toward a role of iNKT cells in liver damage.

Activation of T-bet, FOXP3, and EOMES in Target Organs From Piglets Infected With the Virulent PRRSV-1 Lena Strain

Transcription factors (TFs) modulate genes involved in cell-type-specific proliferative and migratory properties, metabolic features, and effector functions. Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important pathogen agents in the porcine industry; however, TFs have been poorly studied during the course of this disease. Therefore, we aimed to evaluate the expressions of the TFs T-bet, GATA3, FOXP3, and Eomesodermin (EOMES) in target organs (the lung, tracheobronchial lymph node, and thymus) and those of different effector cytokines (IFNG, TNFA, and IL10) and the Fas ligand (FASL) during the early phase of infection with PRRSV-1 strains of different virulence. Target organs from mock-, virulent Lena-, and low virulent 3249-infected animals humanely euthanized at 1, 3, 6, 8, and 13 days post-infection (dpi) were collected to analyze the PRRSV viral load, histopathological lesions, and relative quantification through reverse transcription quantitative PCR (RT-qPCR) of the TFs and cytokines. Animals belonging to both infected groups, but mainly those infected with the virulent Lena strain, showed upregulation of the TFs T-bet, EOMES, and FOXP3, together with an increase of the cytokine IFN-γ in target organs at the end of the study (approximately 2 weeks post-infection). These results are suggestive of a stronger polarization to Th1 cells and regulatory T cells (Tregs), but also CD4+ cytotoxic T lymphocytes (CTLs), effector CD8+ T cells, and γδT cells in virulent PRRSV-1-infected animals; however, their biological functionality should be the object of further studies.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

Neutrophilia, lymphopenia and myeloid dysfunction: a living review of the quantitative changes to innate and adaptive immune cells which define COVID-19 pathology

Destabilization of balanced immune cell numbers and frequencies is a common feature of viral infections. This occurs due to, and further enhances, viral immune evasion and survival. Since the discovery of the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), which manifests in coronavirus disease 2019 (COVID-19), a great number of studies have described the association between this virus and pathologically increased or decreased immune cell counts. In this review, we consider the absolute and relative changes to innate and adaptive immune cell numbers, in COVID-19. In severe disease particularly, neutrophils are increased, which can lead to inflammation and tissue damage. Dysregulation of other granulocytes, basophils and eosinophils represents an unusual COVID-19 phenomenon. Contrastingly, the impact on the different types of monocytes leans more strongly to an altered phenotype, e.g. HLA-DR expression, rather than numerical changes. However, it is the adaptive immune response that bears the most profound impact of SARS-CoV-2 infection. T cell lymphopenia correlates with increased risk of intensive care unit admission and death; therefore, this parameter is particularly important for clinical decision-making. Mild and severe diseases differ in the rate of immune cell counts returning to normal levels post disease. Tracking the recovery trajectories of various immune cell counts may also have implications for long-term COVID-19 monitoring. This review represents a snapshot of our current knowledge, showing that much has been achieved in a short period of time. Alterations in counts of distinct immune cells represent an accessible metric to inform patient care decisions or predict disease outcomes.

Too young to die? How aging affects cellular innate immune responses to influenza virus and disease severity

Influenza is a respiratory viral infection that causes significant morbidity and mortality worldwide. The innate immune cell response elicited during influenza A virus (IAV) infection forms the critical first line of defense, which typically is impaired as we age. As such, elderly individuals more commonly succumb to influenza-associated complications, which is reflected in most aged animal models of IAV infection. Here, we review the important roles of several major innate immune cell populations in influenza pathogenesis, some of which being deleterious to the host, and the current knowledge of how age-associated numerical, phenotypic and functional cell changes impact disease development. Further investigation into age-related modulation of innate immune cell responses, using appropriate animal models, will help reveal how immunity to IAV may be compromised by aging and inform the development of novel therapies, tailored for use in this vulnerable group.

Ceramide and Related Molecules in Viral Infections

Ceramide is a lipid messenger at the heart of sphingolipid metabolism. In concert with its metabolizing enzymes, particularly sphingomyelinases, it has key roles in regulating the physical properties of biological membranes, including the formation of membrane microdomains. Thus, ceramide and its related molecules have been attributed significant roles in nearly all steps of the viral life cycle: they may serve directly as receptors or co-receptors for viral entry, form microdomains that cluster entry receptors and/or enable them to adopt the required conformation or regulate their cell surface expression. Sphingolipids can regulate all forms of viral uptake, often through sphingomyelinase activation, and mediate endosomal escape and intracellular trafficking. Ceramide can be key for the formation of viral replication sites. Sphingomyelinases often mediate the release of new virions from infected cells. Moreover, sphingolipids can contribute to viral-induced apoptosis and morbidity in viral diseases, as well as virus immune evasion. Alpha-galactosylceramide, in particular, also plays a significant role in immune modulation in response to viral infections. This review will discuss the roles of ceramide and its related molecules in the different steps of the viral life cycle. We will also discuss how novel strategies could exploit these for therapeutic benefit.

Brief Report: Diminished Coinhibitory Molecule 2B4 Expression Is Associated With Preserved iNKT Cell Phenotype in HIV Long-Term Nonprogressors

BACKGROUND

We have previously shown an association of elevated coinhibitory molecule 2B4 expression with iNKT cells alterations in HIV disease. Herein, we show a comparative analysis of 2B4 expression on iNKT cells of HIV long-term nonprogressors (LTNPs) and progressors.

METHODS

Antiretroviral therapy-naive HIV-seropositive individuals (progressors, n = 16) and LTNPs (n = 10) were recruited for this study. We used multicolor flow cytometry on frozen peripheral blood mononuclear cells to determine iNKT subset frequencies, the levels of coinhibitory 2B4 expression, and intracellular interferon-γ (IFN-γ) production. CD1d tetramer was used to characterize iNKT cells.

RESULTS

We report significantly lower level of 2B4 expression on bulk LTNPs iNKT cells and on their CD4 subsets compared with HIV progressors. Furthermore, the iNKT cells from LTNPs produced higher amount of IFN-γ than HIV progressors as detected by intracellular cytokine staining. Interestingly, the frequency of 2B4iNKT cells of progressors but not LTNPs significantly correlates with CD4 T-cell count, HIV viral load, and IFN-γ production by iNKT cells.

CONCLUSION

Our results suggest that in addition to suppressed HIV replication, diminished 2B4 expression and associated coinhibitory signaling, and substantial production of IFN-γ could contribute to preserved iNKT cell phenotype in LTNPs.

Contribution of NKT cells to the immune response and pathogenesis triggered by respiratory viruses

Human respiratory syncytial virus (hRSV) and human metapneumovirus (hMPV) cause acute respiratory tract infections in children worldwide. Natural killer T (NKT) cells are unconventional T lymphocytes, and their TCRs recognize glycolipids bound to the MHC-I-like molecule, CD1d. These cells modulate the inflammatory response in viral infections. Here, we evaluated the contribution of NKT cells in both hRSV and hMPV infections. A significant decrease in the number of neutrophils, eosinophils, and CD103⁺DCs infiltrating to the lungs, as well as an increased production of IFN-γ, were observed upon hRSV-infection in CD1d-deficient BALB/c mice, as compared to wild-type control mice. However, this effect was not observed in the CD1d-deficient BALB/c group, upon infection with hMPV. Importantly, reduced expression of CD1d in CD11b⁺ DCs and epithelial cells was found in hRSV -but not hMPV-infected mice. Besides, a reduction in the expression of CD1d in alveolar macrophages of lungs from hRSV- and hMPV-infected mice was found. Such reduction of CD1d expression interfered with NKT cells activation, and consequently IL-2 secretion, as characterized by in vitro experiments for both hRSV and hMPV infections. Furthermore, increased numbers of NKT cells recruited to the lungs in response to hRSV- but not hMPV-infection was detected, resulting in a reduction in the expression of IFN-γ and IL-2 by these cells. In conclusion, both hRSV and hMPV might be differently impairing NKT cells function and contributing to the immune response triggered by these viruses.

Polar functional group-containing glycolipid CD1d ligands modulate cytokine-biasing responses and prevent experimental colitis

The MHC class I-like molecule CD1d is a nonpolymorphic antigen-presenting glycoprotein, and its ligands include glycolipids, such as α-GalCer. The complexes between CD1d and ligands activate natural killer T cells by T cell receptor recognition, leading to the secretion of various cytokines (IFN-γ, IL-4, IL-17A, etc.). Herein, we report structure-activity relationship studies of α-GalCer derivatives containing various functional groups in their lipid acyl chains. Several derivatives have been identified as potent CD1d ligands displaying higher cytokine induction levels and/or unique cytokine polarization. The studies also indicated that flexibility of the lipid moiety can affect the binding affinity, the total cytokine production level and/or cytokine biasing. Based on our immunological evaluation and investigation of physicochemical properties, we chose bisamide- and Bz amide-containing derivatives 2 and 3, and evaluated their in vivo efficacy in a DSS-induced model of ulcerative colitis. The derivative 3 that exhibits Th2- and Th17-biasing responses, demonstrated significant protective effects against intestinal inflammation in the DSS-induced model, after a single intraperitoneal injection.

An association of iNKT+/CD3+/CD161+ lymphocytes in ovarian cancer tissue with CA125 serum concentration

The purpose of this study was to investigate the association of iNKT (human invariant natural killer T) cells with the key marker of ovarian cancer (OC) - CA125 (cancer antigen125) in serum. The study reports the assessment of iNKT cells in peripheral blood and tissue of benign and borderline ovarian tumors (BOTs) and in the advanced-stage ovarian cancer. The study groups were as follows: 25 women with benign ovarian tumors, 11 women with BOTs, and 24 women with primary advanced-stage ovarian cancers. The control group consisted of 20 patients without the ovarian pathology. The rates of iNKT lymphocytes in the peripheral blood and tissue specimens were evaluated by a flow cytometry. Significant differences in the percentage of iNKT+/CD3+ of CD3+ lymphocytes, iNKT+/CD3+/CD161+ among CD3+ and iNKT+/CD3+/CD161+ among CD3+/iNKT+ between the control group and patients with ovarian tumors in the peripheral blood and tumor tissue were identified. Significant correlations were noticed between the proportion of lymphocytes iNKT+/CD3+/CD161+ among CD3+/iNKT cells in blood and in cancer tissue of both benign and malignant tumors. In the OC group, neither the ratio of iNKT cells in the blood (P = 0.07), nor the intra-tumor NKT-cell infiltration (P = 0.5) were independent prognostic factors for the follow-up. An increased rate of iNKT cells was detected in benign ovarian tumors compared to OCs. In patients with ovarian cancer, a higher rate of iNKT cells in tumor tissue was present related to that noted in the patient's blood. In addition, a correlation was discovered between the CA125 serum marker and NKT cells from the ovarian cancer tissue. This article has for the first time demonstrated a negative relationship between serum levels and NKT lymphocyte count from ovarian tissue. The inflammatory process in ovarian cancer tissue and the potential infiltration of endothelial immune cells, may result in a reduced number of NKT cells in the tumor microenvironment and increased circulation of the CA125 marker. Presented findings underscore new aspects of the iNKT cells involvement in the ovarian cancer development.

Chronic Viral Liver Diseases: Approaching the Liver Using T Cell Receptor-Mediated Gene Technologies

Chronic infection with viral hepatitis is a major risk factor for liver injury and hepatocellular carcinoma (HCC). One major contributing factor to the chronicity is the dysfunction of virus-specific T cell immunity. T cells engineered to express virus-specific T cell receptors (TCRs) may be a therapeutic option to improve host antiviral responses and have demonstrated clinical success against virus-associated tumours. This review aims to give an overview of TCRs identified from viral hepatitis research and discuss how translational lessons learned from cancer immunotherapy can be applied to the field. TCR isolation pipelines, liver homing signals, cell type options, as well as safety considerations will be discussed herein.

Roles of Macrophage Migration Inhibitory Factor in Dengue Pathogenesis: From Pathogenic Factor to Therapeutic Target

Dengue virus (DENV) infection is the most prevalent mosquito-borne viral infection and can lead to severe dengue hemorrhagic fever (DHF) and even life-threatening dengue shock syndrome (DSS). Although the cytokine storm has been revealed as a critical factor in dengue disease, the limited understanding of dengue immunopathogenesis hinders the development of effective treatments. Macrophage migration inhibitory factor (MIF) is a pleiotropic proinflammatory cytokine that mediates diverse immune responses, and the serum level of MIF positively correlates with disease severity in patients with dengue. MIF is involved in DENV replication and many pathological changes, such as vascular leakage, during DENV infection. In this paper, the pathogenic roles of MIF and the regulation of MIF secretion during DENV infection are reviewed. Furthermore, whether MIF is a potential therapeutic target against DENV infection is also discussed.

Concentration of NK cells after β-glucan and vitamin D supplementation in patients with diabetic retinopathy

In our study, we focused on possible effects of supplementation with glucan and vitamin D on total numbers of NK cells in patients with diabetic retinopathy. We evaluated possible relations among nutritional state (BMI), leptin levels, and total numbers of NK cells in patients supplemented with (1) glucan and vitamin D, (2) vitamin D and placebo, and (3) vitamin D alone. Our results show that 3 months of supplementation with both glucan and vitamin D resulted in significant improvements of NK cell numbers. In addition, we found statistically significant correlation between NK cell numbers and leptin levels. Based on these results, we propose that the molecule responsible for these changes is glucan, as vitamin D alone or together with placebo caused no effects.

Viral strategies predisposing to respiratory bacterial superinfections

Acute respiratory infections are amongst the leading causes of childhood morbidity and mortality globally. Viruses are the predominant cause of such infections, but mixed etiologies with bacteria has for decades raised the question of the interplay between them in causality and determination of the outcome of such infections. In this review, we examine recent microbiological, biochemical, and immunological advances that contribute to elucidating the mechanisms by which infections by specific viruses enable bacterial infections in the airway, and exacerbate them. We analyze specific domains in which viruses play such facilitating role including enhancement of bacterial adhesion by unmasking cryptic receptors and upregulation of adhesion proteins, disruption of tight junction integrity favoring paracellular transmigration of bacteria and loss of epithelial barrier integrity, increased availability of nutrient, such as mucins and iron, alteration of innate and adaptive immune responses, and disabling defense against bacteria, and lastly, changes in airway microbiome that render the lung more vulnerable to pathogens. Separate exhaustive analysis of each domain focuses on individuals with cystic fibrosis (CF), in whom viruses may play a key role in paving the way for the primary injury that leads to permanence of bacterial pathogens, viruses may then serve as triggers for "CF exacerbations"; these constituting the signature and ultimately the outcome determinants of these patients.

Perturbation of mucosal-associated invariant T cells and iNKT cells in HIV infection

PURPOSE OF REVIEW

To analyze the possible role that the 'unconventional' T-cell populations mucosal-associated invariant T cell (MAIT) and iNKT cells play during HIV infection and following antiretroviral therapy (ART) treatment.

RECENT FINDINGS

A substantial body of evidence now demonstrates that both MAIT and iNKT cells are depleted in blood during HIV infection. The depletion and dysfunction of MAIT and iNKT cells are only partially restored by suppressive ART, potentially contributing to HIV-related comorbidities.

SUMMARY

The deficiency and dysfunction of MAIT and iNKT T-cell subsets likely impact on immunity to important coinfections including Mycobacterium tuberculosis. This underscores the importance of research on restoring these unconventional T cells during HIV infection. Future studies in this field should address the challenge of studying tissue-resident cells, particularly in the gut, and better defining the determinants of MAIT/iNKT cell dysfunction. Such studies could have a significant impact on improving the immune function of HIV-infected individuals.

Increased cytoplasmatic expression of cancer immune surveillance receptor CD1d in anaplastic thyroid carcinomas

BACKGROUND

Anaplastic thyroid carcinomas are associated with rapid tumor growth, short survival time and without any promising therapy to improve the poor prognosis. In this study, expression of immunoregulative receptor CD1d and lymphocyte infiltration in different thyroid tumors as well as in healthy tissue were analyzed in order to find new targets for an immunotherapeutic approach.

METHODS

CD1d immunohistochemistry was performed in samples of 18 anaplastic, 17 follicular, 27 papillary, and 4 medullary thyroid carcinomas as well as in 19 specimens from normal thyroid tissue and additionally in 10 samples of sarcoma, seven malignant melanoma and three spindle-cell lung carcinoma. Furthermore, thyroid samples were stained with antibodies against CD3, CD20, CD56, CD68, and LCA in order to analyze lymphocyte infiltration.

RESULTS

For the first time CD1d receptor expression on normal thyroid tissue could be demonstrated. Moreover, anaplastic thyroid carcinomas showed significantly higher expression levels compared to other thyroid samples. Most astonishingly, CD1d expression disappeared from the cellular surface and was detected rather in the cytoplasm of anaplastic thyroid carcinoma cells. In addition, histologically similar tumors to anaplastic carcinoma like sarcoma and malignant melanoma revealed distinct CD1d staining patterns. Furthermore, infiltration of T cells, B cells, and macrophages in anaplastic thyroid carcinomas was different when compared to normal thyroid tissue and all other thyroid carcinomas.

CONCLUSIONS

Anaplastic thyroid carcinomas show significantly higher expression of CD1d, a receptor for NKT cells, which are subject of several anticancer therapy studies. These results may offer a novel approach to explore immunotherapeutic treatment options.

Features and therapeutic potential of T-cell receptors in high-grade glioma

BACKGROUND

Previous studies have shown that endogenous T cells play an important role in the prolonged survival time of high-grade glioma (HGG) patients. Our objectives were to investigate the features of T-cell receptor (TCR) repertoires in HGG patients and to elucidate any potential therapeutic value.

METHODS

During November 2011 and December 2018, tumor tissues and blood samples of 35 patients with HGG who underwent surgery at Beijing Tiantan Hospital or Beijing Shijitan Hospital were selected after surgery. After isolating DNA from samples, multiple rounds of PCR were performed to establish a DNA immune repertoire (IR). Then, the sequences and frequencies of the complementarity-determining 3 (CDR3) region in TCR beta chain (TRB) were identified by high-throughput sequencing and IR analysis. A survival follow-up was conducted monthly thereafter until December 2018. Finally, the t test and Mann-Whitney test were used to compare statistical differences between two sets of data.

RESULTS

The Shannon diversity index (SHDI) of TRB sequences of HGG patients was significantly lower than that of healthy individuals (7.34 vs. 8.45, P = 0.001). The SHDI of TRB sequences of glioblastoma (GBM) patients with more than 16 months survival time was much higher than that of GBM patients with shorter survival times in both tumor tissues (3.48 ± 0.31 vs. 6.21 ± 0.33, t = -5.49, P = 0.002) and blood cells (6.02 ± 0.66 vs. 7.44 ± 0.32, t = -2.20, P = 0.036). In addition, patients achieved a distinctly higher proportion compared to that of healthy individuals in the proportion of TRBV9 and TRBV5 functional regions (9.83% vs. 6.83%, P = 0.001). Surgical tissue from patients who survived more than 16 months yielded a much higher proportion of TRBV4 and TRBV9 regions (7.14% vs. 3.28%, t = 3.18, P = 0.019). In surgical tissues from two GBM patients who survived for longer than 46 months, we found a potentially therapeutic TCR sequence.

CONCLUSIONS

HGG patients have less species diversity of TCR repertoires compared with that of healthy individuals. TRBV9 regions in TCRs may be protective factors for long-term survival of GBM patients.

iNKT cells and hematopoietic stem cell transplantation: Two-phase activation of iNKT cells may improve outcome

Invariant natural killer T cells (iNKT) produce large amounts of different cytokines which can influence differentiation, polarization and activation of immune cells, particularly NK and T cells. iNKT have been shown to suppress GvHD and promote anti-tumor and anti-pathogen immunity. There are highly specific and safe synthetic ligands such as alpha-galactosylceramide (α-GalCer) and C20:2 which activate iNKT cells toward relatively Th1 and Th2 pathways, respectively. Bone marrow transplantation (BMT) or 'hematopoietic stem cell transplantation' (HSCT) is effective for leukemia and lymphoma through 'graft-versus-leukemia' (GVL) immunity. However, frequent serious complications include graft-versus-host-disease (GVHD), opportunistic infections and relapse. Both GVHD and GVL are mediated by T cells. Manipulating iNKT by different lipid analogues in early and late phases after transplantation may suppress GVHD and graft rejection and enhance GVL effect, as well as resistance to opportunistic infections and so, could be a novel and effective strategy for improving HSCT outcome.

Critical Role of an MHC Class I-Like/Innate-Like T Cell Immune Surveillance System in Host Defense against Ranavirus (Frog Virus 3) Infection

Besides the central role of classical Major Histocompatibility Complex (MHC) class Ia-restricted conventional Cluster of Differentiation 8 (CD8) T cells in antiviral host immune response, the amphibian Xenopus laevis critically rely on MHC class I-like (mhc1b10.1.L or XNC10)-restricted innate-like (i)T cells (iVα6 T cells) to control infection by the ranavirus Frog virus 3 (FV3). To complement and extend our previous reverse genetic studies showing that iVα6 T cells are required for tadpole survival, as well as for timely and effective adult viral clearance, we examined the conditions and kinetics of iVα6 T cell response against FV3. Using a FV3 knock-out (KO) growth-defective mutant, we found that upregulation of the XNC10 restricting class I-like gene and the rapid recruitment of iVα6 T cells depend on detectable viral replication and productive FV3 infection. In addition, by in vivo depletion with XNC10 tetramers, we demonstrated the direct antiviral effector function of iVα6 T cells. Notably, the transitory iV6 T cell defect delayed innate interferon and cytokine gene response, resulting in long-lasting negative inability to control FV3 infection. These findings suggest that in Xenopus and likely other amphibians, an immune surveillance system based on the early activation of iT cells by non-polymorphic MHC class-I like molecules is important for efficient antiviral immune response.

Delivery of oncolytic vaccinia virus by matched allogeneic stem cells overcomes critical innate and adaptive immune barriers

Background

Previous studies have identified IFNγ as an important early barrier to oncolytic viruses including vaccinia. The existing innate and adaptive immune barriers restricting oncolytic virotherapy, however, can be overcome using autologous or allogeneic mesenchymal stem cells as carrier cells with unique immunosuppressive properties.

Methods

To test the ability of mesenchymal stem cells to overcome innate and adaptive immune barriers and to successfully deliver oncolytic vaccinia virus to tumor cells, we performed flow cytometry and virus plaque assay analysis of ex vivo co-cultures of stem cells infected with vaccinia virus in the presence of peripheral blood mononuclear cells from healthy donors. Comparative analysis was performed to establish statistically significant correlations and to evaluate the effect of stem cells on the activity of key immune cell populations.

Results

Here, we demonstrate that adipose-derived stem cells (ADSCs) have the potential to eradicate resistant tumor cells through a combination of potent virus amplification and sensitization of the tumor cells to virus infection. Moreover, the ADSCs demonstrate ability to function as a virus-amplifying Trojan horse in the presence of both autologous and allogeneic human PBMCs, which can be linked to the intrinsic immunosuppressive properties of stem cells and their unique potential to overcome innate and adaptive immune barriers. The clinical application of ready-to-use ex vivo expanded allogeneic stem cell lines, however, appears significantly restricted by patient-specific allogeneic differences associated with the induction of potent anti-stem cell cytotoxic and IFNγ responses. These allogeneic responses originate from both innate (NK)- and adaptive (T)- immune cells and might compromise therapeutic efficacy through direct elimination of the stem cells or the induction of an anti-viral state, which can block the potential of the Trojan horse to amplify and deliver vaccinia virus to the tumor.

Conclusions

Overall, our findings and data indicate the feasibility to establish simple and informative assays that capture critically important patient-specific differences in the immune responses to the virus and stem cells, which allows for proper patient-stem cell matching and enables the effective use of off-the-shelf allogeneic cell-based delivery platforms, thus providing a more practical and commercially viable alternative to the autologous stem cell approach.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1829-z) contains supplementary material, which is available to authorized users.

Myristoylated rhinovirus VP4 protein activates TLR2-dependent proinflammatory gene expression

Asthma exacerbations are often caused by rhinovirus (RV). We and others have shown that Toll-like receptor 2 (TLR2), a membrane surface receptor that recognizes bacterial lipopeptides and lipoteichoic acid, is required and sufficient for RV-induced proinflammatory responses in vitro and in vivo. We hypothesized that viral protein-4 (VP4), an internal capsid protein that is myristoylated upon viral replication and externalized upon viral binding, is a ligand for TLR2. Recombinant VP4 and myristoylated VP4 (MyrVP4) were purified by Ni-affinity chromatography. MyrVP4 was also purified from RV-A1B-infected HeLa cells by urea solubilization and anti-VP4 affinity chromatography. Finally, synthetic MyrVP4 was produced by chemical peptide synthesis. MyrVP4-TLR2 interactions were assessed by confocal fluorescence microscopy, fluorescence resonance energy transfer (FRET), and monitoring VP4-induced cytokine mRNA expression in the presence of anti-TLR2 and anti-VP4. MyrVP4 and TLR2 colocalized in TLR2-expressing HEK-293 cells, mouse bone marrow-derived macrophages, human bronchoalveolar macrophages, and human airway epithelial cells. Colocalization was absent in TLR2-null HEK-293 cells and blocked by anti-TLR2 and anti-VP4. Cy3-labeled MyrVP4 and Cy5-labeled anti-TLR2 showed an average fractional FRET efficiency of 0.24 ± 0.05, and Cy5-labeled anti-TLR2 increased and unlabeled MyrVP4 decreased FRET efficiency. MyrVP4-induced chemokine mRNA expression was higher than that elicited by VP4 alone and was attenuated by anti-TLR2 and anti-VP4. Cytokine expression was similarly increased by MyrVP4 purified from RV-infected HeLa cells and synthetic MyrVP4. We conclude that, during RV infection, MyrVP4 and TLR2 interact to generate a proinflammatory response.

Innovation in Chemistry, Manufacturing, and Controls-A Regulatory Perspective From Industry

This review describes the landscape of novel modalities such as cell and gene therapies, viruses, other novel biologics, oligomers, and emerging technologies, including modern analytics. We summarize the regulatory history and recent landmark developments in some major markets and examine specific chemistry, manufacturing, and controls (CMC) challenges, including suggestions for exploration of potential science-based approaches in support of regulatory strategy development from an industry perspective. In addition, we evaluate the economic factors contributing to patient access to innovation and discuss the impact of regulation. There is a desperate need for a consistent form of regulation where global approaches to regulatory strategies can be harmonized, and specific CMC challenges can be dealt with using the appropriate science and risk-based tools. Although these tools are well described in current guidance documents, the specifics of applicability to complex novel modalities can still result in differing regulatory advice and outcomes. The future goals for efficiently regulating innovative modalities and technologies could be aided by more regulatory harmonization, regulatory education, and industry cooperation through consortia, enabling industry to supply key information to regulators in a transparent yet well-defined manner, and utilizing mutually understood risk-benefit analyses to produce drugs with appropriate safety, efficacy, and quality characteristics.

Roles, function and relevance of LAG3 in HIV infection

HIV causes several forms of immune dysfunction that need to be addressed in a functional cure for HIV. Immune exhaustion describes a dysfunctional phenotype caused by chronic cellular activation. Lymphocyte activation gene-3 (LAG3) is one of several negative coreceptors known as immune checkpoints that contribute to this exhaustion phenotype. Antibodies targeting immune checkpoints are now used clinically to restore immunity against cancer and hold promise in restoring immunity during HIV infection. Here, we summarize current knowledge surrounding LAG3 and discuss its relevance during HIV infection and the potential for LAG3-targeting antibodies in a functional HIV cure.

Small Animal Models of Respiratory Viral Infection Related to Asthma

Respiratory viral infections are strongly associated with asthma exacerbations. Rhinovirus is most frequently-detected pathogen; followed by respiratory syncytial virus; metapneumovirus; parainfluenza virus; enterovirus and coronavirus. In addition; viral infection; in combination with genetics; allergen exposure; microbiome and other pathogens; may play a role in asthma development. In particular; asthma development has been linked to wheezing-associated respiratory viral infections in early life. To understand underlying mechanisms of viral-induced airways disease; investigators have studied respiratory viral infections in small animals. This report reviews animal models of human respiratory viral infection employing mice; rats; guinea pigs; hamsters and ferrets. Investigators have modeled asthma exacerbations by infecting mice with allergic airways disease. Asthma development has been modeled by administration of virus to immature animals. Small animal models of respiratory viral infection will identify cell and molecular targets for the treatment of asthma.

Herpes Simplex Virus 1 Specifically Targets Human CD1d Antigen Presentation To Enhance Its Pathogenicity

Herpes simplex virus 1 (HSV-1) is one of the most prevalent herpesviruses in humans and represents a constant health threat to aged and immunocompromised populations. How HSV-1 interacts with the host immune system to efficiently establish infection and latency is only partially known. CD1d-restricted NKT cells are a critical arm of the host innate immune system and play potent roles in anti-infection and antitumor immune responses. We discovered previously that upon infection, HSV-1 rapidly and efficiently downregulates CD1d expression on the cell surface and suppresses the function of NKT cells. Furthermore, we identified the viral serine/threonine protein kinase US3 as a major viral factor downregulating CD1d during infection. Interestingly, neither HSV-1 nor its US3 protein efficiently inhibits mouse CD1d expression, suggesting that HSV-1 has coevolved with the human immune system to specifically suppress human CD1d (hCD1d) and NKT cell function for its pathogenesis. This is consistent with the fact that wild-type mice are mostly resistant to HSV-1 infection. On the other hand, in vivo infection of CD1d-humanized mice (hCD1d knock-in mice) showed that HSV-1 can indeed evade hCD1d function and establish infection in these mice. We also report here that US3-deficient viruses cannot efficiently infect hCD1d knock-in mice but infect mice lacking all NKT cells at a higher efficiency. Together, these studies supported HSV-1 evasion of human CD1d and NKT cell function as an important pathogenic factor for the virus. Our results also validated the potent roles of NKT cells in antiherpesvirus immune responses and pointed to the potential of NKT cell ligands as adjuvants for future vaccine development.IMPORTANCE Herpes simplex virus 1 (HSV-1) is among the most common human pathogens. Little is known regarding the exact mechanism by which this virus evades the human immune system, particularly the innate immune system. We reported previously that HSV-1 employs its protein kinase US3 to modulate the expression of the key antigen-presenting molecule, CD1d, so as to evade the antiviral function of NKT cells. Here we demonstrated that the virus has coevolved with the human CD1d and NKT cell system and that NKT cells indeed play potent roles in anti-HSV immune responses. These studies point to the great potential of exploring NKT cell ligands as adjuvants for HSV vaccines.

Increased levels of interleukin-22 in thoracic aorta and plasma from patients with acute thoracic aortic dissection

BACKGROUND

Interleukin (IL)-22 plays important roles in the development of arterial disease, including atherosclerosis and hypertension. However, the relationship between IL-22 and acute thoracic aortic dissection (TAD) remains unknown.

METHODS

Blood samples were collected from patients with chest pain who underwent computed tomography angiography of the thoracic aorta but had no known preoperative diagnosis of coronary artery disease, peripheral artery disease, arthritis, and/or membranous nephropathy. Patients were divided into non-AD (NAD) and TAD groups, and the plasma concentrations of IL-22, IL-6 and tumor necrosis factor (TNF)-α were measured. In addition, aortic tissue samples from acute TAD patients and normal donors were collected, and the expression levels of IL-22 and IL-22 receptor 1 (IL-22R1) were measured.

RESULTS

IL-22, IL-6 and TNF-α levels were significantly higher in acute TAD patients than in NAD patients (IL-22, NAD group: 27.0 (19.1, 38.6) pg/ml vs. TAD group: 32.9 (20.6, 58.3) pg/ml, p<0.0001). The correlation analysis showed that IL-22 levels were positively correlated with levels of IL-6, TNF-α, fasting glucose, blood pressure, white blood cells, C-reactive proteins and D-dimers. Binary logistic regression analyses showed that IL-22 was independently associated with the presence of acute TAD (OR 1.169, 95% CI 1.069 to 1.277; p=0.001). In addition, compared with aortic tissue of normal controls, TAD aortas showed increased expression of IL-22 and IL-22R1, especially in the torn section (IL-22, non-torn section: 2.8±0.5/HPF vs. torn section 2.8±0.5/HPF, p<0.001). Additionally, macrophage but not T lymphocyte infiltration was significantly increased in the torn section (Macrophage, non-torn section: 2.2±0.6/HPF vs. torn section 5.7±1.2/HPF, p<0.001; T lymphocyte, non-torn section: 2.7±0.9/HPF vs. torn section 2.4±0.5/HPF, p=0.28), as evidenced by increased positive staining for the macrophage marker CD68, as opposed to the T cell marker CD3.

CONCLUSION

IL-22 levels may correlate with the presence of acute TAD.

Interleukin-22, a potent target for treatment of non-autoimmune diseases

Interleukin -22 (IL-22) is a member of interleukin-10 (IL-10) family cytokines that is produced by different types of lymphocytes included in both innate and adaptive immune systems. These lymphocytes include activated T cells, most notably Th17 and Th22 cells, as well as NK cells, γδ T cells, etc. IL-22 mediate its effects via the IL-22-IL-22R complex and subsequent Janus Kinase-signal transduces and activators transcription (JAK-STAT) signaling pathway. According to recent evidence, IL-22 played a critical role in the pathogenesis of many non-autoimmune diseases. In this review, we mainly discussed the recent findings and advancements of the role of IL-22 in several non-autoimmune diseases, such as acute lung injury, atherosclerosis and some bacterial infections, suggesting that IL-22 may have therapeutic potential for treating non-autoimmune diseases.

Activities of stromal and immune cells in HPV-related cancers

The immune system is composed of immune as well as non-immune cells. As this system is a well-established component of human papillomavirus- (HPV)-related carcinogenesis, high risk human papillomavirus (hrHPV) prevents its routes and mechanisms in order to cause the persistence of infection. Among these mechanisms are those originated from stromal cells, which include the cancer-associated fibroblasts (CAFs), the myeloid-derived suppressor cells (MDSCs) and the host infected cells themselves, i.e. the keratinocytes. These types of cells play central role since they modulate immune cells activities to create a prosperous milieu for cancer development, and the knowledge how such interactions occur are essential for prognostic assessment and development of preventive and therapeutic approaches. Nevertheless, the precise mechanisms are not completely understood, and this lack of knowledge precluded the development of entirely efficient immunotherapeutic strategies for HPV-associated tumors. As a result, an intense work for attaining how host immune response works, and developing of effective therapies has been applied in the last decade. Based on this, this review aims to discuss the major mechanisms of immune and non-immune cells modulated by hrHPV and the potential and existing immunotherapies involving such mechanisms in HPV-related cancers. It is noticed that the combination of immunotherapies has been demonstrated to be essential for obtaining better results, especially because the possibility of increasing the modulating capacity of the HPV-tumor microenvironment has been shown to be central in strengthening the host immune system.

Macrophage Transactivation for Chemokine Production Identified as a Negative Regulator of Granulomatous Inflammation Using Agent-Based Modeling

Cellular activation in trans by interferons, cytokines, and chemokines is a commonly recognized mechanism to amplify immune effector function and limit pathogen spread. However, an optimal host response also requires that collateral damage associated with inflammation is limited. This may be particularly so in the case of granulomatous inflammation, where an excessive number and/or excessively florid granulomas can have significant pathological consequences. Here, we have combined transcriptomics, agent-based modeling, and in vivo experimental approaches to study constraints on hepatic granuloma formation in a murine model of experimental leishmaniasis. We demonstrate that chemokine production by non-infected Kupffer cells in the Leishmania donovani-infected liver promotes competition with infected KCs for available iNKT cells, ultimately inhibiting the extent of granulomatous inflammation. We propose trans-activation for chemokine production as a novel broadly applicable mechanism that may operate early in infection to limit excessive focal inflammation.

CD1-Restricted T Cells During Persistent Virus Infections: "Sympathy for the Devil"

Some of the clinically most important viruses persist in the human host after acute infection. In this situation, the host immune system and the viral pathogen attempt to establish an equilibrium. At best, overt disease is avoided. This attempt may fail, however, resulting in eventual loss of viral control or inadequate immune regulation. Consequently, direct virus-induced tissue damage or immunopathology may occur. The cluster of differentiation 1 (CD1) family of non-classical major histocompatibility complex class I molecules are known to present hydrophobic, primarily lipid antigens. There is ample evidence that both CD1-dependent and CD1-independent mechanisms activate CD1-restricted T cells during persistent virus infections. Sophisticated viral mechanisms subvert these immune responses and help the pathogens to avoid clearance from the host organism. CD1-restricted T cells are not only crucial for the antiviral host defense but may also contribute to tissue damage. This review highlights the two edged role of CD1-restricted T cells in persistent virus infections and summarizes the viral immune evasion mechanisms that target these fascinating immune cells.

Infection and Transport of Herpes Simplex Virus Type 1 in Neurons: Role of the Cytoskeleton

Herpes simplex virus type 1 (HSV-1) is a neuroinvasive human pathogen that has the ability to infect and replicate within epithelial cells and neurons and establish a life-long latent infection in sensory neurons. HSV-1 depends on the host cellular cytoskeleton for entry, replication, and exit. Therefore, HSV-1 has adapted mechanisms to promote its survival by exploiting the microtubule and actin cytoskeletons to direct its active transport, infection, and spread between neurons and epithelial cells during primary and recurrent infections. This review will focus on the currently known mechanisms utilized by HSV-1 to harness the neuronal cytoskeleton, molecular motors, and the secretory and exocytic pathways for efficient virus entry, axonal transport, replication, assembly, and exit from the distinct functional compartments (cell body and axon) of the highly polarized sensory neurons.

New Directions for Natural Killer T Cells in the Immunotherapy of Cancer

Natural killer T (NKT) cells have been placed at the interface between innate and adaptive immunity by a long series of experiments that convincingly showed that beyond cytokine secretion and NK cell recruitment, NKT cells were coordinating dendritic cell and B cell maturation through direct membrane contacts and initiate productive responses. As such, NKT cells are the cellular adjuvant of many immune reactions and have functions that go much beyond what their name encapsulates. In addition, the initial discovery of the ligands of NKT cells is deeply linked to cancer biology and therapy. However, for a host of reasons, animal models in which agonists of NKT cells were used did not translate well to human cancers. A systematic reassessment of NKT cells role in tumorigenesis, especially spontaneous one, is now accessible using single cell analysis technologies both in mouse and man, and should be taken advantage of. Similarly, the migration, localization, phenotype of NKT cells following induced expansion after injection of an agonist can be examined at the single cell level. This technological revolution will help evaluate where and how NKT cells can be used in cancer.

Critical Role for Very-Long Chain Sphingolipids in Invariant Natural Killer T Cell Development and Homeostasis

The role of sphingolipids (SLs) in the immune system has come under increasing scrutiny recently due to the emerging contributions that these important membrane components play in regulating a variety of immunological processes. The acyl chain length of SLs appears particularly critical in determining SL function. Here, we show a role for very-long acyl chain SLs (VLC-SLs) in invariant natural killer T (iNKT) cell maturation in the thymus and homeostasis in the liver. Ceramide synthase 2-null mice, which lack VLC-SLs, were susceptible to a hepatotropic strain of lymphocytic choriomeningitis virus, which is due to a reduction in the number of iNKT cells. Bone marrow chimera experiments indicated that hematopoietic-derived VLC-SLs are essential for maturation of iNKT cells in the thymus, whereas parenchymal-derived VLC-SLs are crucial for iNKT cell survival and maintenance in the liver. Our findings suggest a critical role for VLC-SL in iNKT cell physiology.

Effects of self-reported sensitivity and road-traffic noise levels on the immune system

Sensitivity to noise, particularly road traffic noise, can increase cortisol levels and result in changes in immune system biomarkers. Therefore, continuous exposure to noise can have an effect on immune function, hormonal levels, and cardiovascular function, leading to hypertension and stress. The purpose of this study was to investigate the changes in stress-and immune system-related biomarkers according to the self-reported sensitivity to noise and exposure to road traffic noise, to ultimately determine the potential effects of noise on health. A survey was conducted through questionnaire (ISO/TS 15666) sent to 172 female subjects in Korea, including 128 from Ulsan and 44 from Seoul. The average noise level was calculated, and blood samples were collected for measurements of cortisol levels, Natural killer (NK) / Natural killer T (NKT) cell populations, and NK cell activity (through measurements of interleukin-12 (IL-12) and interferon-gamma (INF-γ) concentrations). Multivariate linear regression analysis of the measured biomarkers according to the road traffic noise level and self-reported noise sensitivity was conducted adjusting for the effects of age, alcohol status, smoking status, regular exercise, and residence period. IL-12 levels increased, whereas the NKT cell population decreased with increasing noise levels. The results further suggested that cortisol levels are more influenced by the subject’s sensitivity to noise than to the level of chronic road traffic noise. Therefore, noise appears to have the largest effect on IL-12 levels as well as the population and activity of NKT cells. In conclusion, our results suggest that low-level road traffic noise and sensitivity to noise can affect health by causing changes in the immune response through mechanisms other than increased cortisol.