CD1d affects the proliferation, migration, and apoptosis of human papillary thyroid carcinoma TPC-1 cells via regulating MAPK/NF-κB signaling pathway.

The study aimed to investigate the effect of CD1d down-regulation on the proliferation, migration, and apoptosis of papillary thyroid carcinoma cells and explore the underlying mechanism. CD1d expression was silenced in TPC-1 cells by transfection of CD1d siRNA lentivirus. The proliferation, apoptosis rate, and migration ability of TPC-1 cells were detected by CCK-8 assay, flow cytometry, and scratch assay, respectively. Western blot and qPCR analyses were performed to detect the expression of related proteins. CD1d was highly expressed in TPC-1 cells. Down-regulation of CD1d significantly decreased ALMS1, CDKN3, CDK6, Ki-67, Bcl2 expression, increased Bax and Caspase 3 expression (all P < 0.05), and decreased the migration ability of TPC-1 cells. Gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to identify the relevant signaling pathways. KEGG pathway enrichment analysis showed that the differentially expressed genes were mainly enriched in MAPK and NF-κB signaling pathways. Our findings suggest that CD1d down-regulation inhibited the proliferation and migration abilities of TPC-1 cells, increased cell apoptosis possibly via the MAPK/NF-κB signaling pathway.

Human CD4+ iNKT cell adoptive immunotherapy induces anti-tumour responses against CD1d-negative EBV-driven B lymphoma.

Invariant natural killer T (iNKT) cells are a conserved population of innate T lymphocytes that are uniquely suitable as off-the-shelf cellular immunotherapies due to their lack of alloreactivity. Two major subpopulations of human iNKT cells have been delineated, a CD4- subset that has a TH1/cytolytic profile, and a CD4+ subset that appears polyfunctional and can produce both regulatory and immunostimulatory cytokines. Whether these two subsets differ in anti-tumour effects is not known. Using live cell imaging, we found that CD4- iNKT cells limited growth of CD1d+ Epstein-Barr virus (EBV)-infected B-lymphoblastoid spheroids in vitro, whereas CD4+ iNKT cells showed little or no direct anti-tumour activity. However, the effects of the two subsets were reversed when we tested them as adoptive immunotherapies in vivo using a xenograft model of EBV-driven human B cell lymphoma. We found that EBV-infected B cells down-regulated CD1d in vivo, and administering CD4- iNKT cells had no discernable impact on tumour mass. In contrast, xenotransplanted mice bearing lymphomas showed rapid reduction in tumour mass after administering CD4+ iNKT cells. Immunotherapeutic CD4+ iNKT cells trafficked to both spleen and tumour and were associated with subsequently enhanced responses of xenotransplanted human T cells against EBV. CD4+ iNKT cells also had adjuvant-like effects on monocyte-derived DCs and promoted antigen-dependent responses of human T cells in vitro. These results show that allogeneic CD4+ iNKT cellular immunotherapy leads to marked anti-tumour activity through indirect pathways that do not require tumour cell CD1d expression and that are associated with enhanced activity of antigen-specific T cells.

Ox-LDL-induced CD80+ macrophages expand pro-atherosclerotic NKT cells via CD1d in atherosclerotic mice and hyperlipidemic patients.

Atherosclerosis is an inflammatory disease of blood vessels involving the immune system. Natural killer T (NKT) cells, as crucial components of the innate and acquired immune systems, play critical roles in the development of atherosclerosis. However, the mechanism and clinical relevance of NKT cells in early atherosclerosis are largely unclear. The study investigated the mechanism influencing NKT cell function in apoE deficiency-induced early atherosclerosis. Our findings demonstrated that there were higher populations of NKT cells and interferon-gamma (IFN-γ)-producing NKT cells in the peripheral blood of patients with hyperlipidemia and in the aorta, blood, spleen, and bone marrow of early atherosclerotic mice compared with the control groups. Moreover, we discovered that the infiltration of CD80+ macrophages and CD1d expression on CD80+ macrophages in atherosclerotic mice climbed remarkably. CD1d expression increased in CD80+ macrophages stimulated by oxidized low-density lipoprotein (ox-LDL) ex vivo and in vitro. Ex vivo coculture of macrophages with NKT cells revealed that ox-LDL-induced CD80+ macrophages presented lipid antigen α-Galcer (alpha-galactosylceramide) to NKT cells via CD1d, enabling NKT cells to express more IFN-γ. Furthermore, a greater proportion of CD1d+ monocytes and CD1d+CD80+ monocytes were found in peripheral blood of hyperlipidemic patients compared with that of healthy donors. Positive correlations were found between CD1d+CD80+ monocytes and NKT cells or IFN-γ+ NKT cells in hyperlipidemic patients. Our findings illustrated that CD80+ macrophages stimulated NKT cells to secrete IFN-γ via CD1d-presenting α-Galcer, which may accelerate the progression of early atherosclerosis. Inhibiting lipid antigen presentation by CD80+ macrophages to NKT cells may be a promising immune target for the treatment of early atherosclerosis.NEW & NOTEWORTHY This work proposed the ox-LDL-CD80+ monocyte/macrophage-CD1d-NKT cell-IFN-γ axis in the progression of atherosclerosis. The proinflammatory IFN-γ+ NKT cells are closely related to CD1d+CD80+ monocytes in hyperlipidemic patients. Inhibiting CD80+ macrophages to present lipid antigens to NKT cells through CD1d blocking may be a new therapeutic target for atherosclerosis.

CD1 molecules: Beyond antigen presentation.

CD1 molecules are well known for their role in binding and presenting lipid antigens to mediate the activation of CD1-restricted T cells. However, much less appreciated is the fact that CD1 molecules can have additional "unconventional" roles which impact the activation and functions of CD1-expressing cells, ultimately controlling tissue homeostasis as well as the progression of inflammatory and infectious diseases. Some of these roles are mediated by so-called reverse signalling, by which crosslinking of CD1 molecules at the cell surface initiates intracellular signalling. On the other hand, CD1 molecules can also control metabolic and inflammatory pathways in CD1-expressing cells through cell-intrinsic mechanisms independent of CD1 ligation. Here, we review the evidence for "unconventional" functions of CD1 molecules and the outcomes of such roles for health and disease.

CD1d protects against hepatocyte apoptosis in non-alcoholic steatohepatitis.

BACKGROUND & AIMS: Hepatocyte apoptosis, a well-defined form of cell death in non-alcoholic steatohepatitis (NASH), is considered the primary cause of liver inflammation and fibrosis. However, the mechanisms underlying the regulation of hepatocyte apoptosis in NASH remain largely unclear. We explored the anti-apoptotic effect of hepatocyte CD1d in NASH. METHODS: Hepatocyte CD1d expression was analyzed in patients with NASH and mouse models. Hepatocyte-specific gene overexpression or knockdown and anti-CD1d crosslinking were used to investigate the anti-apoptotic effect of hepatocyte CD1d on lipotoxicity-, Fas-, and concanavalin (ConA)-mediated liver injuries. A high-fat diet, a methionine-choline-deficient diet, a Fas agonist, and ConA were used to induce lipotoxic and/or apoptotic liver injuries. Palmitic acid was used to mimic lipotoxicity-induced apoptosis in vitro. RESULTS: We identified a dramatic decrease in CD1d expression in hepatocytes of patients with NASH and mouse models. Hepatocyte-specific CD1d overexpression and knockdown experiments collectively demonstrated that hepatocyte CD1d protected against hepatocyte apoptosis and alleviated hepatic inflammation and injuries in NASH mice. Furthermore, decreased JAK2-STAT3 signaling was observed in NASH patient livers. Mechanistically, anti-CD1d crosslinking on hepatocytes induced tyrosine phosphorylation of the CD1d cytoplasmic tail, leading to the recruitment and phosphorylation of JAK2. Phosphorylated JAK2 activated STAT3 and subsequently reduced apoptosis in hepatocytes, which was associated with an increase in anti-apoptotic effectors (Bcl-xL and Mcl-1) and a decrease in pro-apoptotic effectors (cleaved-caspase 3/7). Moreover, anti-CD1d crosslinking effectively protected against Fas- or ConA-mediated hepatocyte apoptosis and liver injury in mice. CONCLUSIONS: Our study uncovered a previously unrecognized anti-apoptotic CD1d-JAK2-STAT3 axis in hepatocytes that conferred hepatoprotection and highlighted the potential of hepatocyte CD1d-directed therapy for liver injury and fibrosis in NASH, as well as in other liver diseases associated with hepatocyte apoptosis. IMPACT AND IMPLICATIONS: Excessive and/or sustained hepatocyte apoptosis is critical in driving liver inflammation and injury. The mechanisms underlying the regulation of hepatocyte apoptosis in non-alcoholic steatohepatitis (NASH) remain largely unclear. Here, we found that CD1d expression in hepatocytes substantially decreases and negatively correlates with the severity of liver injury in patients with NASH. We further revealed a previously unrecognized anti-apoptotic CD1d-JAK2-STAT3 signaling axis in hepatocytes, which confers significant protection against liver injury in NASH and acute liver diseases. Thus, hepatocyte CD1d-targeted therapy could be a promising strategy to manipulate liver injury in both NASH and other hepatocyte apoptosis-related liver diseases.

Contribution of NKT cells and CD1d-expressing cells in obesity-associated adipose tissue inflammation.

Natural killer T (NKT) cell are members of the innate-like T lymphocytes and recognizes lipid antigens presented by CD1d-expressing cells. Obesity-associated inflammation in adipose tissue (AT) leads to metabolic dysfunction, including insulin resistance. When cellular communication is properly regulated among AT-residing immune cells and adipocytes during inflammation, a favorable balance of Th1 and Th2 immune responses is achieved. NKT cells play crucial roles in AT inflammation, influencing the development of diet-induced obesity and insulin resistance. NKT cells interact with CD1d-expressing cells in AT, such as adipocytes, macrophages, and dendritic cells, shaping pro-inflammatory or anti-inflammatory microenvironments with distinct characteristics depending on the antigen-presenting cells. Additionally, CD1d may be involved in the inflammatory process independently of NKT cells. In this mini-review, we provide a brief overview of the current understanding of the interaction between immune cells, focusing on NKT cells and CD1d signaling, which control AT inflammation both in the presence and absence of NKT cells. We aim to enhance our understanding of the mechanisms of obesity-associated diseases.

The immune system in neurological diseases: What innate-like T cells have to say.

The immune system classically consists of 2 lines of defense, innate and adaptive, both of which interact with one another effectively to protect us against any pathogenic threats. Importantly, there is a diverse subset of cells known as innate-like T cells that act as a bridge between the innate and adaptive immune systems and are pivotal players in eliciting inflammatory immune responses. A growing body of evidence has demonstrated the regulatory impact of these innate-like T cells in central nervous system (CNS) diseases and that such immune cells can traffic into the brain in multiple pathological conditions, which can be typically attributed to the breakdown of the blood-brain barrier. However, until now, it has been poorly understood whether innate-like T cells have direct protective or causative properties, particularly in CNS diseases. Therefore, in this review, our attention is focused on discussing the critical roles of 3 unique subsets of unconventional T cells, namely, natural killer T cells, γδ T cells, and mucosal-associated invariant T cells, in the context of CNS diseases, disorders, and injuries and how the interplay of these immune cells modulates CNS pathology, in an attempt to gain a better understanding of their complex functions.

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.

Varicella zoster virus downregulates expression of the non-classical antigen presentation molecule CD1d.

BACKGROUND: The non-classical antigen presentation molecule CD1d presents lipid antigens to invariant natural killer T (iNKT) cells. Activation of these cells triggers a rapid cytokine response providing an interface between innate and adaptive immune responses. The importance of CD1d and iNKT cells in varicella zoster virus (VZV) infection has been emphasised by clinical reports of individuals with CD1d or iNKT cell deficiencies experiencing severe, disseminated varicella post-vaccination. METHODS: Three strains of VZV, VZV-S, rOka, and VZV rOka-66S were used to infect Jurkat cells. Flow cytometry of VZV- and mock-infected cells assessed the modulatory impact of VZV on CD1d. Infected cell-supernatant and transwell coculture experiments explored the role of soluble factors in VZV-mediated immunomodulation. CD1d transcripts were assessed by RT-qPCR. RESULTS: Surface and intracellular flow cytometry demonstrated CD1d was strikingly downregulated by VZV-S and rOka in both infected and VZV antigen-negative cells compared to mock. CD1d downregulation is cell-contact-dependant and CD1d transcripts are targeted by VZV. Mechanistic investigations using rOka-66S (unable to express the viral kinase ORF66), implicate this protein in CD1d modulation in infected cells. CONCLUSIONS: VZV implements multiple mechanisms targeting both CD1d transcript and protein. This provides evidence of VZV interaction with and manipulation of the CD1d-iNKT cell axis.

Sex-based differences in natural killer T cell-mediated protection against diet-induced steatohepatitis in Balb/c mice.

BACKGROUND: Metabolic dysfunction-associated steatotic liver disease (MASLD) is prevalent in Western countries, evolving into metabolic dysfunction-associated steatohepatitis (MASH) with a sexual dimorphism. Fertile women exhibit lower MASLD risk than men, which diminishes post-menopause. While NKT-cell involvement in steatohepatitis is debated, discrepancies may stem from varied mouse strains used, predominantly C57BL6/J with Th1-dominant responses. Exploration of steatohepatitis, encompassing both genders, using Balb/c background, with Th2-dominant immune response, and CD1d-deficient mice in the Balb/c background (lacking Type I and Type II NKT cells) can clarify gender disparities and NKT-cell influence on MASH progression. METHODS: A high fat and choline-deficient (HFCD) diet was used in male and female mice, Balb/c mice or CD1d-/- mice in the Balb/c background that exhibit a Th2-dominant immune response. Liver fibrosis and inflammatory gene expression were measured by qPCR, and histology assessment. NKT cells, T cells, macrophages and neutrophils were assessed by flow cytometry. RESULTS: Female mice displayed milder steatohepatitis after 6 weeks of HFCD, showing reduced liver damage, inflammation, and fibrosis compared to males. Male Balb/c mice exhibited NKT-cell protection against steatohepatitis whereas CD1d-/- males on HFCD presented decreased hepatoprotection, increased liver fibrosis, inflammation, neutrophilic infiltration, and inflammatory macrophages. In contrast, the NKT-cell role was negligible in early steatohepatitis development in both female mice, as fibrosis and inflammation were similar despite augmented liver damage in CD1d-/- females. Relevant, hepatic type I NKT levels in female Balb/c mice were significantly lower than in male. CONCLUSIONS: NKT cells exert a protective role against experimental steatohepatitis as HFCD-treated CD1d-/- males had more severe fibrosis and inflammation than male Balb/c mice. In females, the HFCD-induced hepatocellular damage and the immune response are less affected by NKT cells on early steatohepatitis progression, underscoring sex-specific NKT-cell influence in MASH development.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common liver condition today. In its more advanced form, called metabolic dysfunction-associated steatohepatitis (MASH), adult men are more often affected than women, though this difference vanishes after menopause. Various factors contribute to MASH, including a specific immune cell type called NKT cells, which has not been deeply researched yet. To explore the role of NKT cells in steatohepatitis, we used male and female mice with or without NKT cells (CD1d^−/− mice), feeding them a high-fat diet that induces steatohepatitis. Our findings revealed that female mice had less severe steatohepatitis compared to males. Interestingly, we observed a protective role of NKT cells during steatohepatitis, as male mice without these cells had more damage, inflammation, and fibrosis than those with NKT cells. However, in females, even though those lacking NKT cells showed more liver damage and immune alterations, NKT did not seem to play a major role in early steatohepatitis progression. Notably, females had much fewer NKT cells in their livers compared to males, possibly explaining this difference. In conclusion, NKT cells seem to slow down steatohepatitis progression, especially in male mice. In females, their impact on early steatohepatitis advance appears more limited.

Novel lipid antigens for NKT cells in cancer.

Cancer immunotherapy aims to unleash the power of the immune system against tumors without the side effects of traditional chemotherapy. Immunotherapeutic methods vary widely, but all follow the same basic principle: overcome the barriers utilized by cancers to avoid immune destruction. These approaches often revolve around classical T cells, such as with CAR T cells and neoantigen vaccines; however, the utility of the innate-like iNKT cell in cancer immunotherapy has gained significant recognition. iNKT cells parallel classic T cell recognition of peptide antigens presented on MHC through their recognition of lipid antigens presented on the MHC I-like molecule CD1d. Altered metabolism and a lipogenic phenotype are essential properties of tumor cells, representing a unique feature that may be exploited by iNKT cells. In this review, we will cover properties of iNKT cells, CD1d, and lipid antigen presentation. Next, we will discuss the cancer lipidome and how it may be exploited by iNKT cells through a window of opportunity. Finally, we will review, in detail, novel lipid antigens for iNKT cells in cancer.

Invariant NKT cells are more abundant in peanut-allergic adults and a subset of CD8+ iNKT cells are depleted after peanut oil exposure.

Introduction: Peanut allergy is one of the most prevalent food allergies globally. Currently, most research into the mechanisms involved in protein allergy focuses on the protein allergens under investigation, and information on the function of accompanying compounds, such as lipids, is scarce. Thus, this research investigates the role of peanut-associated lipids and invariant natural killer T (iNKT) cells in peanut allergy using a novel, human, in vitro assay. Methods: PBMCs from non-allergic and peanut-allergic subjects were stimulated with the glycolipid, α-Galactosylceramide (α-GalCer), over 14 days for iNKT cell expansion. Autologous dendritic cells (DCs) were stimulated with either peanut oil, the lipid-binding peanut allergen, Ara h 8, or both peanut oil and Ara h 8. The expanded iNKT cells were then immunomagnetically isolated and co-cultured for 5 h with autologous DCs, and cytokine expression was measured by flow cytometry. Results: A 5-fold higher iNKT cell population was observed in peanut-allergic subject peripheral blood compared to non-allergic controls. In all subjects, conventional flow analysis highlighted iNKTs co-cultured with autologous α-GalCer-pulsed DCs displayed increased IL-4 and IFN-y secretion within 5 hours of co-culture. A 10-parameter unsupervised clustering analysis of iNKT phenotype found significantly more CD3+CD8+CD25+IL-4+IL-5+IL-10+IFNγ+ cells in non-allergic adults following culture with peanut oil. Conclusion: For the first time, we show iNKT cells are more abundant in peanut-allergic adults compared to non-allergic adults, and peanut lipid-exposed iNKT cells resulted in the identification of a subset of CD8+ iNKT cells which was significantly lower in peanut-allergic adults. Thus, this study proposes a role for iNKT cells and peanut allergen-associated lipids in peanut allergy.

Type 1 invariant natural killer T cells in chronic inflammation and tissue fibrosis.

Chronic tissue inflammation often results in fibrosis characterized by the accumulation of extracellular matrix components remodeling normal tissue architecture and function. Recent studies have suggested common immune mechanisms despite the complexity of the interactions between tissue-specific fibroblasts, macrophages, and distinct immune cell populations that mediate fibrosis in various tissues. Natural killer T (NKT) cells recognizing lipid antigens bound to CD1d molecules have been shown to play an important role in chronic inflammation and fibrosis. Here we review recent data in both experimental models and in humans that suggest a key role of type 1 invariant NKT (iNKT) cell activation in the progression of inflammatory cascades leading to recruitment of neutrophils and activation of the inflammasome, macrophages, fibroblasts, and, ultimately, fibrosis. Emerging evidence suggests that iNKT-associated mechanisms contribute to type 1, type 2 and type 3 immune pathways mediating tissue fibrosis, including idiopathic pulmonary fibrosis (IPF). Thus, targeting a pathway upstream of these immune mechanisms, such as the inhibition of iNKT activation, may be important in modulating various fibrotic conditions.

Anti-CD1d treatment suppresses immunogenic maturation of lung dendritic cells dependent on lung invariant natural killer T cells in asthmatic mice.

Our previous findings show that invariant natural killer T (iNKT)cells can promote immunogenic maturation of lung dendritic cells (LDCs) to enhance Th2 cell responses in asthma. It has been accepted that recognition of glycolipid antigens presented by CD1d molecules by the T cell receptors of iNKT cells leads to iNKT cell activation. Therefore, we examine the immunoregulatory influences of anti-CD1d treatment on Th2 cell response and immunogenic maturation of LDCs and subsequently explored whether these influences were dependent on lung iNKT cells in asthmatic mice. We discoveredthat in wild-type mice sensitized and challenged with house dust mite or ovalbumin (OVA), anti-CD1d treatment inhibited Th2 cell response and immunogenic maturation of LDCs. LDCs from asthmatic mice with anti-CD1d treatment had a markedly decreased influence on Th2 cell responses in vivo and in vitro. Furthermore, anti-CD1d treatment reduced the abundance and activation of lung iNKT cells in asthmatic mice. Moreover, in asthmatic iNKT cell-deficient Jα18-/- mice, anti-CD1d treatment did not influence Th2 cell responses and immunogenic maturation of LDCs. Meanwhile, the quantity of CD40L+ iNKT cells in asthmatic mice was significant decreased by anti-CD1d treatment. Finally, the inhibition of anti-CD1d treatment on LDC immunogenic maturation and Th2 cell responses in asthmatic mice was reversed by anti-CD40 treatment. Our data suggest that anti-CD1d treatment can suppress Th2 cell responses through inhibiting immunogenic maturation of LDCs dependent on lung iNKT cells, which couldbe partially related to the downregulation of CD40L expression on lung iNKT cells in asthmatic mice.

CD1d-Dependent Natural Killer T Cells Mediate Hypertension and Vascular Injury Through Interleukin-17A.

Background Different T-lymphocyte subsets, including CD1d-dependent natural killer T (NKT) cells, play distinct roles in hypertension, highlighting the importance of identifying key immune cells for its treatment. This study aimed to determine the unknown effects of CD1d-dependent NKT cells on hypertension and vascular injury. Methods and Results Hypertension models were induced in male CD1d knockout (CD1dko), wild-type, and adoptive bone marrow transfer mice by angiotensin II (Ang II) or deoxycorticosterone acetate salt. Blood pressure was measured by the tail-cuff system and radiotelemetry. Vascular injury was assessed by histologic studies or aortic ring assay. Inflammation was detected by flow cytometry, quantitative real-time polymerase chain reaction, or ELISA. Results showed that Ang II infusion significantly reduced CD1d expression and NKT cell numbers in the aorta of mice. CD1dko mice exhibited worsened blood pressure elevation, vascular injury, and inflammatory response induced by Ang II or deoxycorticosterone acetate salt. However, these effects were markedly reversed in wild-type mice treated with NKT cell-specific activator. Adoptive transfer of CD1dko bone marrow cells to wild-type mice also significantly worsened Ang II-induced responses. Mechanistically, CD1dko increased Ang II-induced interleukin-6 production and activated signal transducer and activator of transcription 3 and orphan nuclear receptor γ, subsequently inducing interleukin-17A production. Neutralizing interleukin-17A partially reversed Ang II-induced hypertension and vascular injury in CD1dko mice. In addition, levels of NKT cells were lower in the blood of patients with hypertension (n=57) compared with normotensive individuals (n=87). Conclusions These findings reveal a previously unknown role for CD1d-dependent NKT cells in hypertension and vascular injury, indicating that NKT cell activation could be a promising therapeutic target for hypertension.

Lipids regulate peripheral serotonin release via gut CD1d.

The crosstalk between the immune and neuroendocrine systems is critical for intestinal homeostasis and gut-brain communications. However, it remains unclear how immune cells participate in gut sensation of hormones and neurotransmitters release in response to environmental cues, such as self-lipids and microbial lipids. We show here that lipid-mediated engagement of invariant natural killer T (iNKT) cells with enterochromaffin (EC) cells, a subset of intestinal epithelial cells, promoted peripheral serotonin (5-HT) release via a CD1d-dependent manner, regulating gut motility and hemostasis. We also demonstrated that inhibitory sphingolipids from symbiotic microbe Bacteroides fragilis represses 5-HT release. Mechanistically, CD1d ligation on EC cells transduced a signal and restrained potassium conductance through activation of protein tyrosine kinase Pyk2, leading to calcium influx and 5-HT secretion. Together, our data reveal that by engaging with iNKT cells, gut chemosensory cells selectively perceive lipid antigens via CD1d to control 5-HT release, modulating intestinal and systemic homeostasis.

Towards a better understanding of human iNKT cell subpopulations for improved clinical outcomes.

Invariant natural killer T (iNKT) cells are a unique T lymphocyte population expressing semi-invariant T cell receptors (TCRs) that recognise lipid antigens presented by CD1d. iNKT cells exhibit potent anti-tumour activity through direct killing mechanisms and indirectly through triggering the activation of other anti-tumour immune cells. Because of their ability to induce potent anti-tumour responses, particularly when activated by the strong iNKT agonist αGalCer, they have been the subject of intense research to harness iNKT cell-targeted immunotherapies for cancer treatment. However, despite potent anti-tumour efficacy in pre-clinical models, the translation of iNKT cell immunotherapy into human cancer patients has been less successful. This review provides an overview of iNKT cell biology and why they are of interest within the context of cancer immunology. We focus on the iNKT anti-tumour response, the seminal studies that first reported iNKT cytotoxicity, their anti-tumour mechanisms, and the various described subsets within the iNKT cell repertoire. Finally, we discuss several barriers to the successful utilisation of iNKT cells in human cancer immunotherapy, what is required for a better understanding of human iNKT cells, and the future perspectives facilitating their exploitation for improved clinical outcomes.

CD1d-dependent natural killer T-cells inactivation aggravates sepsis-induced myocardial injury via T lymphocytes infiltration and IL-6 production in mice.

Myocardial edema mediated by endothelial dysfunction plays an important role in sepsis-induced cardiomyopathy (SIC); however, its mechanism is unclear. The current study aimed to provide evidence on the cardioprotection of CD1d-dependent natural killer T (NKT) cells and clarify the possible mechanism in a mouse model of sepsis. Wild-type (WT) and CD1d-dependent NKT-cells inactivation (CD1dko) mice were subjected to sepsis induced by intraperitoneal injection of lipopolysaccharide (LPS). The NKT-cells number and CD1d expression were both increased in the hearts and blood of WT mice after LPS treatment. Compared with WT mice, CD1dko mice exhibited remarkably accelerated LPS-induced mortality, cardiac dysfunction, myocardial injury, endothelial apoptosis, microvascular damage, microvascular permeability and cardiac edema. Mechanistically, CD1d deficiency further increased LPS-induced accumulation of T lymphocytes in the myocardium and upregulation of IL-6 protein levels. Administration of an IL-6 neutralizing antibody to CD1dko mice improved cardiac dysfunction, myocardial injury and edema induced by LPS. Our study identified that CD1d-dependent NKT-cells inactivation exacerbated SIC via T lymphocytes infiltration and IL-6 production. Hence, activation of CD1d-dependent NKT cells may be a potential candidate strategy for SIC treatment.

CD1d facilitates African swine fever virus entry into the host cells via clathrin-mediated endocytosis.

African swine fever (ASF) is a highly contagious and acute hemorrhagic viral disease with high morbidity and mortality in domestic pigs and wild boars. The disease has become a global threat to the pig production industry and has caused enormous economic losses in many countries in recent years. However, the molecular mechanism underlying ASF virus (ASFV) entry of the host cells is not fully understood, which restricts the development of vaccines and antiviral-drugs of ASFV. In this study, we found that the host protein CD1d acts as a host factor, which mediates ASFV entry into the host cells. As the main capsid protein on the surface of ASFV virions, p72 can mediate viral entry. Using IP-MS assay, CD1d was identified as a binding partner of p72 on surface of ASFV virions. Knockdown of CD1d expression and blocking the cells with anti-pCD1d antibody, or incubating ASFV virions with soluble CD1d protein could significantly inhibit ASFV infection. CD1d is located on the membrane surface of primary porcine alveolar macrophages (PAMs) and mediates the virus entry via binding to p72. CD1d knockout or CD1d knockdown assay showed that CD1d could facilitate ASFV virions internalization via clathrin-mediated endocytosis (CME). Furthermore, CD1d interacts with EPS15 to mediate ASFV entry via clathrin-mediated endocytosis. Overall, our findings revealed that CD1d is a novel host-entry factor involved in ASFV internalization via the EPS15-clathrin endocytosis axis and a potential target for antiviral intervention.