Natural killer T cells in allergic asthma: implications for the development of novel immunotherapeutical strategies.

Allergic asthma has emerged as a prevalent allergic disease worldwide, affecting most prominently both young individuals and lower-income populations in developing and developed countries. To devise effective and curative immunotherapy, it is crucial to comprehend the intricate nature of this condition, characterized by an immune response imbalance that favors a proinflammatory profile orchestrated by diverse subsets of immune cells. Although the involvement of Natural Killer T (NKT) cells in asthma pathology is frequently implied, their specific contributions to disease onset and progression remain incompletely understood. Given their remarkable ability to modulate the immune response through the rapid secretion of various cytokines, NKT cells represent a promising target for the development of effective immunotherapy against allergic asthma. This review provides a comprehensive summary of the current understanding of NKT cells in the context of allergic asthma, along with novel therapeutic approaches that leverage the functional response of these cells.

Extranodal NK/T-Cell Lymphoma, Nasal Type, Extranasal and Ulcerative Blister Variant, Case Report.

The extranodal natural killer (NK) T-cell lymphoma of nasal type is a form of lymphoma that falls within the WHO/EORTC 2018 classification of cutaneous T-cell lymphomas. It is characterized for being aggressive, infrequent, and destroying midline facial structures; however, it can also be in primary or secondary form at extranasal sites, such as the skin or the gastrointestinal tract, among others. We report the case of an 18-year-old patient with an extranodal NK/T-cell lymphoma located in an extranasal site. The clinical presentation is characterized for being multifocal and with erythematous-violaceous plaques that progress to hemorrhagic blisters and necrotic ulcers. Although this type of lymphoma has been reported previously by others, the presence of blisters is an atypical finding, which we believe has been described only in one case in the medical literature.

Natural Killer T Cell Diversity and Immunotherapy.

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

Invariant Natural Killer T-cells and their subtypes may play a role in the pathogenesis of endometriosis.

OBJECTIVE: To evaluate the frequencies of iNKT cells and their subsets in patients with deep endometriosis. METHODS: A case-control study was conducted between 2013 and 2015, with 73 patients distributed into two groups: 47 women with a histological diagnosis of endometriosis and 26 controls. Peripheral blood, endometriosis lesions, and healthy peritoneal samples were collected on the day of surgery to determine the frequencies of iNKT cells and subtypes via flow cytometry analysis. RESULTS: The authors observed a lower number of iNKT (p = 0.01) and Double-Negative (DN) iNKT cells (p = 0.02) in the blood of patients with endometriosis than in the control group. The number of DN iNKT IL-17+ cells in the secretory phase was lower in the endometriosis group (p = 0.049). There was an increase in the secretion of IL-17 by CD4+ iNKT cells in the blood of patients with endometriosis and severe dysmenorrhea (p = 0.038), and severe acyclic pelvic pain (p = 0.048). Patients with severe dysmenorrhea also had a decreased number of CD4+ CCR7+ cells (p = 0.022). CONCLUSION: The decreased number of total iNKT and DN iNKT cells in patients with endometriosis suggests that iNKT cells play a role in the pathogenesis of endometriosis and can be used to develop new diagnostic and therapeutic agents.

Valganciclovir as Add-On Therapy Modifies the Frequency of NK and NKT Cell Subpopulations in Disseminated Kaposi Sarcoma Patients.

Human herpesvirus-8 infection (HHV-8) is the causative agent of Kaposi sarcoma (KS) and is highly prevalent among people living with HIV (KS/HIV). It has been reported that valganciclovir (VGC) reduces HHV-8 replication in KS/HIV patients. However, currently it is unclear if VGC modifies the frequency and induces changes in markers of immune regulation of immune cells necessary to eliminate HHV8-infected cells, such as Natural Killer (NK) and NK T cells (NKT). This study evaluated the effect of VGC used as antiviral HHV8 therapy in KS patients on the frequency of NK and NKT subpopulations based on the CD27 and CD57 expression, and the immunosenescence markers, PD-1 and KLRG1. Twenty KS/HIV patients were followed-up at baseline (W0), 4 (W4), and 12 weeks (W12) of the study protocol. Among them, 10 patients received a conventional treatment scheme (CT), solely antiretroviral therapy (ART), and 10 patients received a modified treatment regime (MT), including VGC plus ART. In both groups, bleomycin/vincristine was administrated according to the treating physician's decision. The soluble levels of IL-15, PD-L1, PD-L2, and E-cadherin were quantified across the follow-up. Our results showed that the higher IL-15 levels and lower NK frequencies cells in KS/HIV patients reach almost normal values with both treatments regimes at W12. CD27+ NK and NKT cell frequencies increased since W4 on KS/HIV patients with MT. Furthermore, PD-1 expression decreased while KLRG1 increased on NK and NKT subpopulations at W12, and it is accompanied by increased PD-L1 plasma level since W4. Our study highlights the disruption of NK and NKT subpopulations in patients with KS/HIV and explores VGC treatment's contribution to immune reconstitution during the first weeks of treatment.

Invariant Natural Killer T-cells and their subtypes may play a role in the pathogenesis of endometriosis

Abstract Objective To evaluate the frequencies of iNKT cells and their subsets in patients with deep endometriosis. Methods A case-control study was conducted between 2013 and 2015, with 73 patients distributed into two groups: 47 women with a histological diagnosis of endometriosis and 26 controls. Peripheral blood, endometriosis lesions, and healthy peritoneal samples were collected on the day of surgery to determine the frequencies of iNKT cells and subtypes via flow cytometry analysis. Results The authors observed a lower number of iNKT (p= 0.01) and Double-Negative (DN) iNKT cells (p= 0.02) in the blood of patients with endometriosis than in the control group. The number of DN iNKT IL-17+ cells in the secretory phase was lower in the endometriosis group (p= 0.049). There was an increase in the secretion of IL-17 by CD4+ iNKT cells in the blood of patients with endometriosis and severe dysmenorrhea (p= 0.038), and severe acyclic pelvic pain (p= 0.048). Patients with severe dysmenorrhea also had a decreased number of CD4+ CCR7+ cells (p= 0.022). Conclusion The decreased number of total iNKT and DN iNKT cells in patients with endometriosis suggests that iNKT cells play a role in the pathogenesis of endometriosis and can be used to develop new diagnostic and therapeutic agents.

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.

Protective role of NKT cells and macrophage M2-driven phenotype in bleomycin-induced pulmonary fibrosis.

Pulmonary fibrosis is a result of an abnormal wound healing in lung tissue triggered by an excessive accumulation of extracellular matrix proteins, loss of tissue elasticity, and debit of ventilatory function. NKT cells are a major source of Th1 and Th2 cytokines and may be crucial in the polarization of M1/M2 macrophages in pulmonary fibrogenesis. Although there appears to be constant scientific progress in that field, pulmonary fibrosis still exhibits no current cure. From these facts, we hypothesized that NKT cells could influence the development of pulmonary fibrosis via modulation of macrophage activation. Wild type (WT) and NKT type I cell-deficient mice (Jα18-/-) were subjected to the protocol of bleomycin-induced pulmonary fibrosis with or without treatment with NKT cell agonists α-galactosylceramide and sulfatide. The participation of different cell populations, collagen deposition, and protein levels of different cytokines involved in inflammation and fibrosis was evaluated. The results indicate a benign role of NKT cells in Jα18-/- mice and in wild-type α-galactosylceramide-sulfatide-treated groups. These animals presented lower levels of collagen deposition, fibrogenic molecules such as TGF-ß and vimentin and improved survival rates. In contrast, WT mice developed a Th2-driven response augmenting IL-4, 5, and 13 protein synthesis and increased collagen deposition. Furthermore, the arginase-1 metabolic pathway was downregulated in wild-type NKT-activated and knockout mice indicating lower activity of M2 macrophages in lung tissue. Hence, our data suggest that NKT cells play a protective role in this experimental model by down modulating the Th2 milieu, inhibiting M2 polarization and finally preventing fibrosis.

The tumor antigen N-glycolyl-GM3 is a human CD1d ligand capable of mediating B cell and natural killer T cell interaction.

The expression of N-glycolyl-monosialodihexosyl-ganglioside (NGcGM3) in humans is restricted to cancer cells; therefore, it is a tumor antigen. There are measurable quantities of circulating anti-NGcGM3 antibodies (aNGcGM3 Abs) in human serum. Interestingly, some people have circulating Ag-specific immunoglobulins G (IgGs) that are capable of complement mediated cytotoxicity against NGcGM3 positive cells, which is relevant for tumor surveillance. In light of the chemical nature of Ag, we postulated it as a candidate ligand for CD1d. Furthermore, we hypothesize that the immune mechanism involved in the generation of these Abs entails cross talk between B lymphocytes (Bc) and invariant natural killer T cells (iNKT). Combining cellular techniques, such as flow cytometry and biochemical assays, we demonstrated that CD1d binds to NGcGM3 and that human Bc present NGcGM3 in a CD1d context according to two alternative strategies. We also showed that paraformaldehyde treatment of cells expressing CD1d affects the presentation. Finally, by co-culturing primary human Bc with iNKT and measuring Ki-67 expression, we detected a reproducible increment in the proliferation of the iNKT population when Ag was on the medium. Our findings identify a novel, endogenous, human CD1d ligand, which is sufficiently competent to stimulate iNKT. We postulate that CD1d-restricted Bc presentation of NGcGM3 drives effective iNKT activation, an immunological mechanism that has not been previously described for humans, which may contribute to understanding aNGcGM3 occurrence.

CD4+CD25 high Foxp3+ Treg deficiency in a Brazilian patient with Gaucher disease and lupus nephritis.

Gaucher Disease (GD) is a rare autosomal recessive disorder caused by the deficient activity of beta-glucocerebrosidase. GD is one of the lysosomal storage diseases with the most remarkable alterations in the immune system, and that may manifest clinically as autoimmune disorders and malignancy. We reported the immunological evaluation of a patient with GD and lupus nephritis. Decreased absolute values of T, and NK, and an inversion of CD4(+)/CD8(+) ratio, low levels of IgM and normal B cells were found when compared to reference values in a Brazilian population. Absence ofCD4(+)CD25(high)Foxp3(+) Treg and high levels of total NKT, iNKT cells and CD8(+) iNKT subsets were also observed when compared to the healthy control and GD patient without lupus nephritis. Treg subset and CD8(+) iNKT abnormalities might be involved in severe lupus nephritis in a GD patient. We conclude by emphasizing the importance of the immunological evaluation on early diagnosis of autoimmunity contributing to reduce mortality and morbidity of these patients.

In vitro T-cell profile induced by BCG Moreau in healthy Brazilian volunteers.

Tuberculosis (TB) remains the world's leading cause of morbidity and mortality. Although Mycobacterium bovis bacillus Calmette-Guérin (BCG) is the only vaccine currently in use, its efficacy is highly variable. It has been suggested that early antigenic presentation is a pivotal event leading to a better immune response in TB vaccine models. To investigate this further, we compared in vitro cell-mediated immune responses in the context of early sensitization with TB (i.e. healthy adults vaccinated with BCG when they were young, HD; n = 25) to those in its absence (i.e., newborns with naïve immunity to TB, UV; n = 10) by challenging mononuclear cells with BCG Moreau. After 48 hours, CD4+ and CD8+ T cells were harvested from both groups and stained for PD-1/CD25/ FOXP3. In addition, supernatants were assayed for a broad range of cytokines using an array system. The HD group showed robust reactivity to Protein Purified Derivative and BCG while the naïve, UV group did not. Similarly, in terms of PD-1 expression and Treg cells (CD4+/CD25high(+)/FOXP3+), only the HD group showed higher levels in CD4 lymphocytes. Otherwise, only the UV group showed expression of CD25dim+ as an activation marker dependent on BCG infection. In terms of cytokines, the HD group showed higher levels of Th1 (IL-2/TNF-α/IFN-γ) and regulatory (IL-10) profiles, with monocytes, but not Tr1 cells, acting as the main source of IL-10. Taken together, our results highlight critical roles of early sensitization with TB in mounting cell-mediated immune responses.

Células con propiedades inmunoreguladoras y su impacto en la patogénesis de la sepsis / Cells with immunoregulatory properties and their impact in the pathogenesis of sepsis

Sepsis, defined as a systemic inflammatory response syndrome caused by an infection, is a significant cause of mortality worldwide. It is currently accepted that death associated to sepsis is due to an immune hyperactivation state involving the development of a broad proinflammatory response along with alterations in the coagulation system. It is now clear that besides the inflammatory events, the clinical course of sepsis is characterized by the development of an anti-inflammatory response that could lead to death in its attempt to balance the initial response. The purpose of this review is to summarize current mechanisms that explain the pathogenesis of sepsis, underlying the role that cells with immunoregulatory properties play during the course of this complex syndrome. A better understanding of these processes will contribute in the search of more successful therapeutic strategies.

El síndrome de respuesta sistémica consecuencia de una infección, denominado sepsis, constituye una causa significativa de muerte en el mundo. Históricamente se ha aceptado que la muerte por sepsis se debe a un estado de hiperactivación inmunológica, que implica el desarrollo de una vasta respuesta pro-inflamatoria acompañada de alteraciones en el sistema de coagulación. Ahora es claro que además de los sucesos inflamatorios, el curso clínico de la sepsis se caracteriza por el desarrollo de una respuesta anti-inflamatoria que busca contrarrestar la respuesta inicial, y es ésta finalmente en gran parte responsable de la muerte de los pacientes. El propósito de esta revisión es resumir los mecanismos actuales que explican la patogénesis de la sepsis, y específicamente el papel que desempeñan las subpoblaciones celulares con propiedades inmuno-reguladoras durante el curso de la enfermedad. El mejor entendimiento de estos procesos contribuirá a la búsqueda de estrategias terapéuticas más exitosas.