Search

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.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 emerged in China in December 2019 and then rapidly spread worldwide. Why COVID-19 patients with the same clinical condition have different outcomes remains unclear. This study aimed to examine the differences in the phenotype and functions of major populations of immune cells between COVID-19 patients with same severity but different outcomes. Four common type adult inpatients with laboratory confirmed COVID-19 from Beijing YouAn Hospital, Capital Medical University were included in this study. The patients were divided into two groups based on whether or not COVID-19 polymerase chain reaction (PCR)-negative conversion occurred within 3 weeks. Peripheral blood samples were collected to compare the differences in the phenotype and functions of major populations of immune cells between the two groups of patients. The result shows that the proportions of CD3 + CD8 + CD38 + HLA-DR + CD27 - effector T killer cells generally declined, whereas that of CD3 + CD4 + CD8 + double-positive T cells (DPTs) increased in the persistently PCR-positive patients. In summary, considering the imbalance between effector T killer cells/CD3+CD4+CD8+ DPTs was a possible key factor for PCR-negative conversion in patients with COVID-19., (© 2020 Wiley Periodicals LLC.)

Extranodal natural killer T-cell lymphoma (nasal type; NKTCL) is an aggressive malignancy strongly associated with Epstein-Barr virus (EBV) infection. However, the role of EBV in NKTCL development is unclear, largely due to the lack of information about EBV genome and transcriptome in NKTCL. Here, using high-throughput sequencing, we obtained whole genome (n = 27) and transcriptome datasets (n = 18) of EBV derived from NKTCL tumor biopsies. We assembled 27 EBV genomes and detected an average of 1,152 single nucleotide variants and 44.8 indels (<50 bp) of EBV per sample. We also identified frequent focal EBV genome deletions and integrated EBV fragments in the host genome. Moreover, Phylogenetic analysis revealed that NKTCL-derived EBVs are closely clustered; transcriptome analysis revealed less activation of both latent and lytic genes and larger amount of T-cell epitope alterations in NKTCL, as compared with other EBV-associated cancers. Furthermore, we observed transcriptional defects of the BARTs miRNA by deletion, and the disruption of host NHEJ1 by integrated EBV fragment, implying novel pathogenic mechanisms of EBV. Taken together, we reported for the first time global mutational and transcriptional profiles of EBV in NKTCL clinical samples, revealing important somatic events of EBV and providing insights to better understanding of EBV's contribution in tumorigenesis.

We established transfectants expressing T cell receptors (TCRs) either for Vγ1 and Vδ1 (1C116) or for Vγ2 and Vδ2 (2C21) using the TCR-deficient Jurkat T cell line J.RT3-T3.5. The amount of IL-2 secreted from these γδ T cell clones accurately indicated TCR-dependent stimulation. Clone 2C21 was specifically stimulated by previously reported ligands for Vγ2Vδ2 (Vδ2)-TCR such as isopentenyl pyrophospate (IPP), ethylamine, or risedronate. In contrast, clone 1C116 was strongly stimulated through the Vγ1Vδ1 (Vδ1)-TCR by flavonoid glycosides such as hesperidin and linarin, having both rutinose at the A ring and methoxy (-OCH3) substitution at the B ring. Additionally, hesperidin and linarin showed stimulatory activity for peripheral blood mononuclear cell (PBMC)-derived T cells expressing Vδ1-TCR; these activated Vδ1 + T cells also secreted IL-5, IL-13, MIP-1α, MIP-1β and RANTES. Such PBMC-derived Vδ1 + T cells stimulated by hesperidin and linarin suppressed R5-HIV-1-NL(AD8) viral replication in CD4 + NKT cells in a dose-dependent manner. To the best of our knowledge, this is the first demonstration that flavonoid glycosides activate functional Vδ1 + T cells.

There is a need to identify biomarkers predictive of severe dengue. Single-cohort transcriptomics has not yielded generalizable results or parsimonious, predictive gene sets. We analyzed blood samples of dengue patients from seven gene expression datasets (446 samples, five countries) using an integrated multi-cohort analysis framework and identified a 20-gene set that predicts progression to severe dengue. We validated the predictive power of this 20-gene set in three retrospective dengue datasets (84 samples, three countries) and a prospective Colombia cohort (34 patients), with an area under the receiver operating characteristic curve of 0.89, 100% sensitivity, and 76% specificity. The 20-gene dengue severity scores declined during the disease course, suggesting an infection-triggered host response. This 20-gene set is strongly associated with the progression to severe dengue and represents a predictive signature, generalizable across ages, host genetic factors, and virus strains, with potential implications for the development of a host response-based dengue prognostic assay., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

Extranodal NK/T cell lymphoma, nasal type (ENKL) developed in a patient with intestinal Epstein-Barr virus (EBV)-positive T/NK-cell lymphoproliferative disorder (LPD). The patient was a 46-year-old Chinese man who complained of diarrhea and abdominal pain without immune-deficiency. Endoscopy demonstrated ileum ulcers like Crohn's disease, without histological granulomas. His symptoms continued waxing and waning for 3 years until he developed overt lymphoma (ENKL) in the nasal cavity. The ileum lesions exacerbated into a large deep ulcer, and the biopsy specimens from the ileum, including the one 3 years ago, showed infiltration of small lymphocytes containing many EBV-positive T/NK cells without atypia. Thus, the patient illness of intestine was revealed as intestinal EBV-positive T/NK-cell LPD, which might be closely associated with development of ENKL in this patient. In cases of inflammatory bowel disease without typical clinical courses and histological findings, check-up of EBV in the biopsy might help correct diagnosis., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

The characteristics of adult patients with chronic active Epstein-Barr virus infection are poorly recognized, hindering early diagnosis and an improved prognosis. We studied 54 patients with adult-onset chronic active Epstein-Barr virus infection diagnosed between 2005 and 2015. Adult onset was defined as an estimated age of onset of 15 years or older. To characterize the clinical features of these adults, we compared them to those of 75 pediatric cases (estimated age of onset <15 years). We compared the prognosis of adult-onset chronic active Epstein-Barr virus infection with that of patients with nasal-type (n=37) and non-nasal-type (n=45) extranodal NK/T-cell lymphoma. The median estimated age of onset of these lymphomas was 39 years (range, 16-86 years). Compared to patients with pediatric-onset disease, those in whom the chronic active Epstein-Barr virus infection developed in adulthood had a significantly decreased incidence of fever ( P =0.005), but greater frequency of skin lesions ( P <0.001). Moreover, hypersensitivity to mosquito bites and the occurrence of hydroa vacciniforme were less frequent in patients with adult-onset disease ( P <0.001 and P =0.0238, respectively). Thrombocytopenia, high Epstein-Barr virus nuclear antigen antibody titer, and the presence of hemophagocytic syndrome were associated with a poor prognosis ( P =0.0087, P =0.0236, and P =0.0149, respectively). Allogeneic hematopoietic stem cell transplantation may improve survival ( P =0.0289). Compared to pediatric-onset chronic active Epstein-Barr virus infection and extranodal NK/T-cell lymphoma, adult-onset chronic active Epstein-Barr virus infection had a poorer prognosis ( P <0.001 and P =0.0484, respectively). Chronic active Epstein-Barr virus infection can develop in a wide age range, with clinical differences between adult-onset and pediatric-onset disease. Adult-onset chronic active Epstein-Barr virus infection is a disease with a poor prognosis. Further research will be needed., (Copyright © 2018 Ferrata Storti Foundation.)

Increased expression of T cell immunoglobulin and mucin domain-3 (Tim-3) on invariant natural killer T (iNKT) cells is reported in chronic hepatitis B virus (HBV) infection. However, whether Tim-3 regulates iNKT cells in chronic HBV condition remains unclear. In this study, our results showed that the expression of Tim-3 was up-regulated on hepatic iNKT cells from HBV-transgenic (Tg) mice or iNKT cells stimulated with α-galactosylceramide (α-Galcer). Compared with Tim-3 - iNKT cells, Tim-3 + iNKT cells expressed more IFN-γ, IL-4 and CD107a, indicating a strong relationship between Tim-3 and iNKT cell activation. Constantly, treatment of Tim-3 blocking antibodies significantly enhanced the production of IFN-γ, TNF-α, IL-4 and CD107a in iNKT cells both in vivo and in vitro. This Tim-3 - mediated suppression of iNKT cells was further confirmed in Tim-3 knockout (KO) mice. Moreover, Tim-3 blockade promoted α-Galcer-triggered inhibition of HBV replication, displaying as the decreased HBV DNA and HBsAg level in serum, and down-regulated pgRNA expression in liver tissues. Collectively, our data, for the first time, demonstrated the potential role of Tim-3 blockade in promoting iNKT cell-mediated HBV inhibition. Therefore, combination of α-Galcer with Tim-3 blockade might be a promising approach in chronic hepatitis B therapy., (© 2018 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

Activation of invariant NKT (iNKT) cells manifests antiviral immune responses in vivo. However, clinical trials have failed to show consistent hepatitis B virus (HBV) DNA reduction postadministration of iNKT cell-specific agonist α-galactosylceramide (α-GalCer). In this study, we aimed to investigate HBV infection-related iNKT cell defects and explore iNKT cell-based therapeutic potential for chronic hepatitis B (CHB). Liver specimens from 30 HBV-infected hepatocellular carcinoma patients were collected for CD1d/hepatitis B surface Ag (HBsAg) staining and/or intrahepatic iNKT cell assay. Two hundred and six chronic HBV-infected patients (including 130 CHB patients) were enrolled in the study of circulating iNKT cell frequency and function. We found that liver and hepatoma tissue that positively stained for HBsAg had higher CD1d expression as compared with HBsAg negatively stained counterparts. The elevated CD1d expression in infected tissue is supposed to facilitate the iNKT cell-based antiviral effects locally. However, iNKT cell defects that related with disease progression suggested iNKT cells attenuated their effects during chronic HBV infection. The residual iNKT cells in CHB patients showed aberrant activation and hyporesponsiveness to α-GalCer. Exogenous IL-2 fully rescued α-GalCer-induced expansion of iNKT cells from CHB patients, and synergistic effects of IL-2 and IL-15 helped to recover the CD1d-dependent IFN-γ production. In conclusion, our results highlight the increased CD1d expression in HBV-infected liver and differential iNKT cell defects associated with disease progression during chronic HBV infection. The reversibility of iNKT cell defects suggests protective immune responses could be partially recovered in CHB., (Copyright © 2018 by The American Association of Immunologists, Inc.)

Epstein-Barr virus (EBV), which is associated with B-cell proliferative disorders, also transforms T- or natural killer (NK)-lineage cells and has been connected with various T- or NK (T/NK)-cell malignancies, such as extranodal NK/T-cell lymphoma-nasal type and aggressive NK-cell leukemia. Chronic active EBV (CAEBV) disease , which occurs most often in children and young adults in East Asia, is an EBV-associated T-/NK-cell lymphoproliferative disease. Patients with CAEBV often progress to overt lymphoma or leukemia over a long-term clinical course. EBV's transforming capacity in B cells is well characterized, but the molecular pathogenesis of clonal expansion caused by EBV in T/NK cells has not yet been clarified. In the primary infection, EBV infects B cells and epithelial cells and may also infect some T/NK cells. In some individuals, because of poor presentation by specific human leukocyte antigens or the genetic background, EBV-infected T/NK cells evade host immunity and survive. Occasionally, with the help of viral oncogenes, EBV-associated T/NK lymphoproliferative diseases, such as CAEBV, may develop. The subsequent accumulation of genetic mutations and/or epigenetic modifications in driver genes, such as DDX3X and TP53, may lead to overt lymphoma and leukemia. Activation-induced cytidine deaminase and the APOBEC3 family, driven by EBV infection, may induce chromosomal recombination and somatic mutations.

Intravascular lymphoma (IVL) is a rare entity. Most cases are a variant of extranodal diffuse large B cell lymphoma, and fewer than 10% of the published cases are of T cell origin. Only intravascular B cell lymphoma is recognized as a distinct entity in the most recent World Health Organization (WHO) classification of lymphoproliferative disorders. We describe a case of cutaneous natural killer (NK)/T IVL, with a cytotoxic immunophenotype and Epstein-Barr virus (EBV) positivity. However, our case was immunohistochemically negative not only for T cell receptor (TCR)-βF1 and TCR-γ (TCR-silent), but also for CD56, making it the first triple-negative NK/T IVL case to be described. We urge recognition of this NK/T cell lineage intravascular lymphoma due to its particular immunophenotypical profile and its unvarying relationship with EBV. Its occurrence should not be considered a coincidence, but rather a key aspect of the pathogenic background of this haematological neoplasm., (© 2017 John Wiley & Sons Ltd.)

Introduction and Aim: Natural Killer (NK) cells play an important role in innate immune response to viral infections and their high proportion is situated in the liver. The aim of this study was to analyze possible relation between the expression of NK cell receptors and varied intensity of liver lesions in chronic hepatitis C (CHC) in children., Material and Methods: Study included 105 children with CHC - 54 boys and 51 girls, age 13.62 ± 3.48 years. Blood specimens were taken at the day of the liver biopsy. Histological evaluation was performed according to METAVIR scoring system. Circulating NK cells were evaluated by flow cytometry. The results were shown as a proportion of cells expressing evaluated receptor and its' mean fluorescent intensity (MFI)., Results: In 58 children with CHC (55.2%) significant liver fibrosis was observed ( ≥F2). Higher proportion of cells expressing CD158e inhibitory receptors was observed in the group of children with ALT > 2UNL (21.11 ± 14.60 vs. 12.22 ± 8.99%; p = 0.037). While higher proportion of cells expressing inhibitory CD158b receptor was observed in children with significant fibrosis (F ≥ 2) compared to minimal fibrosis (F < 2) - (34.14 ± 12.44 vs. 27.48 ± 8.71%; p = 0.049). Children with advanced fibrosis (F ≥ 3) had higher MFI of NK cell CD 158b receptor than children with fibrosis scored F < 3 - (5344.20 ± 3407.49 vs. 2979.67 ± 1190.64; p = 0.049). Proportion of NK cells expressing CD158b was found a predictor of significant fibrosis in univariate analysis - [OR 1.065; 95%CI (1.07-1.15); p = 0.046]., Conclusions: Higher proportion of NK cells expressing inhibitory CD158b and CD158e receptors is associated with significant liver injury.

Background: In healthy individuals, Cytomegalovirus (CMV) infection is efficiently controlled by CMV-specific cell-mediated immunity (CMI). Functional impairment of CMI in immunocompromized individuals however can lead to uncontrolled CMV replication and severe clinical complications. Close monitoring of CMV-specific CMI is therefore clinically relevant and might allow a reliable prognosis of CMV disease as well as assist personalized therapeutic decisions., Methods: Objective of this work was the optimization and technical validation of an IFN-γ ELISpot assay for a standardized, sensitive and reliable quantification of CMV-reactive effector cells. T-activated® immunodominant CMV IE-1 and pp65 proteins were used as stimulants. All basic assay parameters and reagents were tested and optimized to establish a user-friendly protocol and maximize the signal-to-noise ratio of the ELISpot assay., Results: Optimized and standardized ELISpot revealed low intra-assay, inter-assay and inter-operator variability (coefficient of variation CV below 22%) and CV inter-site was lower than 40%. Good assay linearity was obtained between 6 × 10 4 and 2 × 10 5 PBMC per well upon stimulation with T-activated® IE-1 (R 2  = 0.97) and pp65 (R 2  = 0.99) antigens. Remarkably, stimulation of peripheral blood mononuclear cells (PBMC) with T-activated® IE-1 and pp65 proteins resulted in the activation of a broad range of CMV-reactive effector cells, including CD3 + CD4 + (Th), CD3 + CD8 + (CTL), CD3 - CD56 + (NK) and CD3 + CD56 + (NKT-like) cells. Accordingly, the optimized IFN-γ ELISpot assay revealed very high sensitivity (97%) in a cohort of 45 healthy donors, of which 32 were CMV IgG-seropositive., Conclusion: The combined use of T-activated® IE-1 and pp65 proteins for the stimulation of PBMC with the optimized IFN-γ ELISpot assay represents a highly standardized, valuable tool to monitor the functionality of CMV-specific CMI with great sensitivity and reliability.

Human herpesvirus 8 (HHV-8) is the causative agent of Kaposi sarcoma (KS) and multicentric Castleman disease (MCD), a life-threatening, virally induced B-cell lymphoproliferative disorder. HHV-8 is a B-lymphotropic γ-herpesvirus closely related to the Epstein-Barr virus (EBV). Invariant natural killer T (iNKT) cells are innate-like T cells that play a role in antiviral immunity, specifically in controlling viral replication in EBV-infected B cells. Decline of iNKT cells is associated with age or HIV infection, both situations associated with HHV-8-related diseases. We analyzed iNKT cells in both blood (n = 26) and spleen (n = 9) samples from 32 patients with HHV-8 MCD and compared them with patients with KS (n = 24) and healthy donors (n = 29). We determined that both circulating and splenic iNKT cell frequencies were markedly decreased in patients with HHV-8 MCD and were undetectable in 6 of them. Moreover, iNKT cells from patients with HHV-8 MCD displayed a proliferative defect after stimulation with α-galactosylceramide. These iNKT cell alterations were associated with an imbalance in B-cell subsets, including a significant decrease in memory B cells, particularly of marginal zone (MZ) B cells. Coculture experiments revealed that the decrease in iNKT cells contributed to the alterations in the B-cell subset distribution. These observations contribute to a better understanding of the complex interactions between HHV-8 and immune cells that cause HHV-8-related MCD., (© 2017 by The American Society of Hematology.)

Invariant natural killer T (iNKT) cells are innate-like T cells that respond to lipid antigens presented by CD1d. These immunoregulatory cells have the capacity for rapid cytokine release after antigen recognition and are essential for the activation of multiple arms of the immune response. HIV-1 infection is associated with iNKT cell depletion in the peripheral blood; however, their role in the gastrointestinal-associated lymphoid tissue (GALT) is less well studied. Our results show that iNKT cells are found at a higher frequency in GALT compared with blood, particularly in HIV-1 elite controllers. The capacity of iNKT cells to produce interleukin-4 (IL-4) and IL-10 in the GALT was associated with less immune activation and lower markers of microbial translocation, whereas regulatory T cell frequency showed positive associations with immune activation. We hypothesized that the composition of the microbiota would influence iNKT cell frequency and function. We found positive associations between the abundance of several Bacteroides species and iNKT cell frequency and their capacity to produce IL-4 in the GALT but not in the blood. Overall, our results are consistent with the hypothesis that GALT iNKT cells, influenced by certain bacterial species, may have a key role in regulating immune activation in HIV-1 infection.

Aim: To investigate killer inhibitory and activating receptor expression by natural killer (NK), natural killer T-like (NKT-like) and CD8+ T lymphocytes in patients with chronic hepatitis C virus (HCV) infection with elevated and with persistently normal alanine aminotransferase (PNALT)., Methods: The percentage of peripheral blood Treg cells, KIR2DL3, ILT-2, KIR3DL1, CD160, NKG2D, NKG2C expressing NK, T and NKT-like cells, cytokine production and NK cytotoxicity were determined by flow cytometry. Twenty-one patients with chronic HCV infection with elevated alanine aminotransferase, 11 HCV carriers with persistently normal alanine aminotransferase and 15 healthy volunteers were enrolled., Results: No significant differences were observed in the percentage of total T, NK or NKT-like cells between study groups. Comparing the activating and inhibitory receptor expression by NK cells obtained from HCV carriers with PNALT and chronic HCV hepatitis patients with elevated alanine aminotransferase, NKG2D activating receptor expression was the only receptor showing a significant difference. NKG2D expression of NK cells was significantly lower in patients with elevated alanine aminotransferase. The expression of CD160, NKG2D and NKG2C activating receptor by CD8+ T cells were significantly lower in patients with chronic HCV hepatitis than in healthy controls and in HCV carriers with PNALT. Plasma TGF-β1 levels inversely correlated with NKG2D expression by NK cells. In vitroTGF-β1 treatment inhibited NK cells cytotoxic activity and downregulated NKG2D expression. CD8+ T cells from HCV carriers with PNALT showed significantly elevated expression of CD160, NKG2D and NKG2C activating receptors compared to chronic HCV patients with elevated alanine aminotransferase. Enhanced expression of inhibitory KIR2DL3 receptor, and decreased ILT-2 expression on NK cells were also found in chronic hepatitis C patients compared to healthy controls., Conclusion: Our study demonstrated a complex dysregulation of activating and inhibitory receptor expression, such as decreased NKG2D and CD160 activating receptor expression and increased KIR2DL3 inhibitory receptor expression by NK and cytotoxic T cells and may provide further mechanism contributing to defective cellular immune functions in chronic hepatitis C. Increased NKG2D receptor expression in HCV patients with persistently normal ALT suggests an important pathway for sustaining NK and CD8 T cell function and a protective role against disease progression.

Nasal natural killer T-cell lymphoma (NKTL) is a highly malignant tumor that is closely associated with Epstein-Barr virus (EBV) infection. Latent membrane protein 1 (LMP1) is encoded by EBV and plays an important role in EBV-induced cell transformation. Therefore, we assessed the function of LMP1 as a stimulant of NKTL progression and the underlying mechanism. A human EBV-positive NKTL cell line (SNK-6) was transfected with pcDNA3.1-LMP1, LV-LMP1 shRNA or LV-eukaryotic translation initiation factor 4E (eIF4E)-shRNA. Then, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to assess the proliferation of SNK-6 cells, and cell migration and invasion were analyzed by transwell chamber assay. Flow cytometry was used to analyze the cell cycle and apoptosis. The results showed LMP1 was highly expressed in SNK-6 cells compared with control groups. Following pretreatment with LMP1 shRNA, the proliferation of SNK-6 cells was inhibited and resulted in a G0/G1 phase arrest. A reduction in invasion and migration was also observed. LMP1 silencing promoted cell apoptosis. Further mechanistic analysis suggested that LMP1 overexpression induced the expression of eIF4E, while eIF4E-shRNA dramatically attenuated the increase in cell proliferation, invasion, migration and the inhibition of apoptosis triggered by LMP-1 upregulation. Moreover, the effect of LMP1 on eIF4E expression was mediated by the NF-κB pathway. Therefore, this finding may provide a potential target against NKTL.

Nonclassical MHC class Ib-restricted invariant T (iT) cell subsets are attracting interest because of their potential to regulate immune responses against various pathogens. The biological relevance and evolutionary conservation of iT cells have recently been strengthened by the identification of iT cells (invariant Vα6 [iVα6]) restricted by the nonclassical MHC class Ib molecule XNC10 in the amphibian Xenopus laevis. These iVα6 T cells are functionally similar to mammalian CD1d-restricted invariant NKT cells. Using the amphibian pathogen frog virus 3 (FV3) in combination with XNC10 tetramers and RNA interference loss of function by transgenesis, we show that XNC10-restricted iVα6 T cells are critical for early antiviral immunity in adult X. laevis. Within hours following i.p. FV3 infection, iVα6 T cells were specifically recruited from the spleen into the peritoneum. XNC10 deficiency and concomitant lack of iVα6 T cells resulted in less effective antiviral and macrophage antimicrobial responses, which led to impaired viral clearance, increased viral dissemination, and more pronounced FV3-induced kidney damage. Together, these findings imply that X. laevis XNC10-restricted iVα6 T cells play important roles in the early anti-FV3 response and that, as has been suggested for mammalian invariant NKT cells, they may serve as immune regulators polarizing macrophage effector functions toward more effective antiviral states., (Copyright © 2015 by The American Association of Immunologists, Inc.)

Aggressive nature killer (NK)-cell neoplasm includes aggressive NK-cell leukemia (ANKL) and extranodal NK/T-cell lymphoma (ENKTL), nasal type. ANKL is rare and is characterized by a systemic neoplastic proliferation of NK-cells, usually with a leukemic presentation. ENKTL is a predominantly extranodal lymphoma, occurring mainly in the upper aerodigestive tract. Both are aggressive neoplasms strongly associated with Epstein-Barr virus (EBV). Here we report two patients with aggressive NK-cells neoplasms localized in the bone marrow (BM) who presented as prolonged fever, anemia, and thrombocytopenia. Both were treated initially as infectious disease. Imaging studies revealed splenomegaly without any nodular lesion or lymphadenopathy. BM examination revealed extensive involvement by EBV-positive NK-cells in both cases. Staging workup including nasal examination/biopsy was negative. Both patients passed away in a month. One case showed gains of chromosomes 4q and 9p by array comparative genomic hybridization. Both tumors were diagnostically challenging due to the unusual clinical presentation and absence of leukemic change, tumor mass or lymphadenopathy. Our cases demonstrate that lymphoma should be considered in patients with fever of unknown origin and bone marrow aspiration/biopsy should be performed as early diagnosis and novel therapeutic regimens may benefit these patients.

Background: Intravascular NK-cell lymphoma (IVNKL) is an extremely rare variant of non-Hodgkin lymphoma. To our knowledge, there are only a few cases reported in the English literature. Here, a case of a 29-year-old male with IVNKL involving the skin of the trunk and 4 extremities and liver is presented. A comprehensive literature review is undertaken to summarize the clinical and pathological features of this disorder., Findings: In our case, large neoplastic lymphoid cells are restricted to the lumen of small vessels and exhibit the phenotype of a true NK cell. The morphology and immunophenotype, positivity of EBER and NK-cell origin are similar to other IVNKL cases. In addition, some cases including ours carry a poor prognosis as multiple systems or vital organs are involved., Conclusion: In summary, we report a case of an unusual intravascular lymphoma of NK-cell lineage that displays both clinical and pathological features and compare it with other differential diagnoses. It is important to recognize this rare entity to make an appropriate diagnosis and achieve a better understanding regarding the treatment and prognosis.

Background: Persistent high-risk human papillomavirus (HR-HPV) infection has been implicated in the development of high-grade cervical intraepithelial neoplasia (CIN) and cervical cancer. Invariant natural killer T (iNKT) cells produce large amounts of cytokines to regulate immune responses. However, the role of iNKT cells in human persistent HPV-infected cervical tissues is unknown., Methods: In our study, 201 patients with diagnoses ranging from normal ectocervical tissue to CINIII from June 2010 to May 2012 were enrolled. HPV DNA and HPV types were detected using the hybrid capture-2 HPV DNA test. Flow cytometry was used to investigate iNKT and CD3+ T cell infiltration into cervical tissues. Real-time quantitative reverse transcription-polymerase chain reaction was used to study IFN-γ expression and immunohistochemistry was used to determine CD3+ T cell distribution., Results: A significant increase in iNKT cells was observed in HPV-positive cervical tissues (p < 0.05), especially in CINII-III (p < 0.01). IFN-γ expression was also increased in HPV-positive cervical tissues (p < 0.05). CD3+ T cells were detected among both epithelium and stromal layers in cervical tissues, and the percentage of CD3+ T cells in HPV-positive cervical tissues was similar to that in HPV-negative cervical tissues (p > 0.05)., Conclusions: The iNKT cell aggregation in cervical tissues during the progression from HPV infection to CIN indicates that iNKT cells might play an important role in suppressing immunity. IFN-γ expression could also be related to the HPV infection status. Preventing the accumulation or functioning of iNKT cells in cervical tissues may be a viable method to prevent the development of CIN., Virtual Slides: The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2521874671514142.

CD1d is a nonpolymorphic, MHC class I-like molecule that presents phospholipid and glycosphingolipid Ags to a subset of CD1d-restricted T cells called invariant NKT (iNKT) cells. This CD1d-iNKT cell axis regulates nearly all aspects of both the innate and adaptive immune responses. Expression of CD1d on B cells is suggestive of the ability of these cells to present Ag to, and form cognate interactions with, iNKT cells. In this article, we summarize key evidence regarding the role and regulation of CD1d in normal B cells and in humoral immunity. We then extend the discussion to B cell disorders, with emphasis on autoimmune disease, viral infection, and neoplastic transformation of B lineage cells, in which CD1d expression can be altered as a mechanism of immune evasion and can have both diagnostic and prognostic importance. Finally, we highlight current and future therapeutic strategies that aim to target the CD1d-iNKT cell axis in B cells., (Copyright © 2014 by The American Association of Immunologists, Inc.)

Background: Dengue viral infection is a global health threat without vaccine or specific treatment. The clinical outcome varies from asymptomatic, mild dengue fever (DF) to severe dengue hemorrhagic fever (DHF). While adaptive immune responses were found to be detrimental in the dengue pathogenesis, the roles of earlier innate events remain largely uninvestigated. Invariant natural killer T (iNKT) cells represent innate-like T cells that could dictate subsequent adaptive response but their role in human dengue virus infection is not known. We hypothesized that iNKT cells play a role in human dengue infection., Methods: Blood samples from a well-characterized cohort of children with DF, DHF, in comparison to non-dengue febrile illness (OFI) and healthy controls at various time points were studied. iNKT cells activation were analyzed by the expression of CD69 by flow cytometry. Their cytokine production was then analyzed after α-GalCer stimulation. Further, the CD1d expression on monocytes, and CD69 expression on conventional T cells were measured., Results: iNKT cells were activated during acute dengue infection. The level of iNKT cell activation associates with the disease severity. Furthermore, these iNKT cells had altered functional response to subsequent ex vivo stimulation with α-GalCer. Moreover, during acute dengue infection, monocytic CD1d expression was also upregulated and conventional T cells also became activated., Conclusion: iNKT cells might play an early and critical role in the pathogenesis of severe dengue viral infection in human. Targeting iNKT cells and CD1d serve as a potential therapeutic strategy for severe dengue infection in the future.

After the development of highly active anti-retroviral therapy, it became clear that the majority of emergent HIV-1 is macrophage-tropic and infects CD4⁺, CCR5-expressing cells (R5-tropic). There are three distinct cell populations, R5-tropic, HIV-1-susceptible CD4⁺ cells: (i) natural killer T (NKT) cells, (ii) dendritic cells and macrophages, and (iii) tissue-associated T cells residing primarily at mucosal surfaces. We have confirmed that CD4⁺ NKT cells derived from peripheral blood mononuclear cells (PBMCs) predominantly express CCR5 rather than CXCR4, whereas the reverse is true for CD4⁺ T cells derived from circulating PBMCs, and that R5-tropic HIV-1 expands efficiently in the CD4⁺ NKT cells. Moreover, when PBMCs depleted of CD8α⁺ cells were stimulated in the presence of α-galactosylceramide (α-GalCer) and R5-tropic HIV-1 [NL(AD8)], the production of HIV-1 virions was not suppressed, whereas, similar to the untreated PBMCs, depletion of CD8β⁺ cells from PBMCs significantly inhibited virion production. These findings suggest that CD8αα⁺ but not CD8αβ⁺ cells may have the ability to inhibit R5-tropic HIV-1 replication in CD4⁺ NKT cells. Here, we show that co-culturing R5-tropic HIV-1-infected CD4⁺ NKT cells with CD8αα⁺ γδ T cells, in particular Vγ1Vδ1 cells, but not with CD8αα⁺ NKT cells or CD8αα⁺ dendritic cells, inhibits HIV-1 replication mainly by secreting chemokines, such as macrophage inflammatory proteins 1α and 1β and RANTES. Collectively, these results indicate the importance of CD8αα⁺ γδ T cells in the control of R5-tropic HIV-1 replication and persistence in CD4⁺ NKT cells., (© 2013 John Wiley & Sons Ltd.)

Background: The commensal yeast Candida albicans is a major cause of invasive fungal infections. Despite treatment with antifungal agents, the mortality rate attributed to these types of infection is high. Although numerous cases have been reported regarding a poor outcome for patients with bacterial and C. albicans coinfection, the mechanisms by which the coinfecting bacteria exacerbate the C. albicans infection remain elusive., Methods and Results: We evaluated how glycolipid-mediated activation of invariant natural killer T (iNKT) cells affects the clearance of C. albicans. Surprisingly, C. albicans-infected, glycolipid-treated mice exhibited significantly lower survival rates, increased fungal burden, and higher interleukin (IL)-6 production in the kidneys compared with control mice. Glycolipid-induced exacerbation of C. albicans infection was not observed in interferon-gamma knockout (IFN-γKO) mice. In the C. albicans-infected, glycolipid-treated mice, the number of neutrophils in the blood and bone marrow dramatically decreased in an IFN-γ-dependent manner. Furthermore, mice that were coinfected with C. albicans and nonfermentative gram-negative commensal bacteria exhibited increased fungal burden and inflammatory cytokine production in the kidneys that were dependent on IFN-γ and iNKT cells., Conclusions: Our results indicate that coinfecting commensal bacteria exacerbate C. albicans infection through IFN-γ produced, in part, by iNKT cells.

Individuals with X-linked lymphoproliferative disease lack invariant natural killer T (iNKT) cells and are exquisitely susceptible to Epstein-Barr virus (EBV) infection. To determine whether iNKT cells recognize or regulate EBV, resting B cells were infected with EBV in the presence or absence of iNKT cells. The depletion of iNKT cells increased both viral titers and the frequency of EBV-infected B cells. However, EBV-infected B cells rapidly lost expression of the iNKT cell receptor ligand CD1d, abrogating iNKT cell recognition. To determine whether induced CD1d expression could restore iNKT recognition in EBV-infected cells, lymphoblastoid cell lines (LCL) were treated with AM580, a synthetic retinoic acid receptor-α agonist that upregulates CD1d expression via the nuclear protein, lymphoid enhancer-binding factor 1 (LEF-1). AM580 significantly reduced LEF-1 association at the CD1d promoter region, induced CD1d expression on LCL, and restored iNKT recognition of LCL. CD1d-expressing LCL elicited interferon γ secretion and cytotoxicity by iNKT cells even in the absence of exogenous antigen, suggesting an endogenous iNKT antigen is expressed during EBV infection. These data indicate that iNKT cells may be important for early, innate control of B cell infection by EBV and that downregulation of CD1d may allow EBV to circumvent iNKT cell-mediated immune recognition.

CD1d-restricted T (natural killer T; NKT) cells are important for controlling herpesvirus infections. Interestingly, herpes simplex virus (HSV) can down-regulate CD1d-mediated activation of NKT cells. We have previously shown that the Thr322 residue in the cytoplasmic tail of human CD1d is important for its intracellular trafficking and functional expression. We proposed that the phosphorylation of T322 is a signal for CD1d lysosomal targeting and subsequent degradation. In the current study, we generated dual mutants by substituting the T322 and S323 residues of wild-type (WT) CD1d with Ala (non-phosphorylatable) or Asp (mimicking phosphorylation) and ectopically expressed them in human embryonic kidney 293 cells. We found that the surface expression levels of the CD1d mutants was in this order: T322AS323A > WT > T322A > S323A > S323D > T322D > T322DS323D. Our results therefore suggest that mimicking the phosphorylation of both T322 and S323 has a cumulative negative effect on the functional expression of CD1d. As previously reported, we also found that upon an HSV infection, antigen presentation by WT CD1d is reduced and the CD1d molecule is degraded. Interestingly, the T322A/S323A double mutation inhibited CD1d degradation and rescued CD1d-mediated antigen presentation following an HSV-1 infection. This suggests that the T322/S323 dyad may be phosphorylated, which then targets CD1d for lysosomal degradation post-infection as a means of immune evasion, explaining (at least in part) the reduced antigen presentation observed. Hence, our findings strongly suggest that T322 and S323 form a dual residue motif that can regulate the functional expression of CD1d during a viral infection., (© 2013 John Wiley & Sons Ltd.)

The IL-33/ST2 axis is known to be involved in liver pathologies. Although, the IL-33 levels increased in sera of viral hepatitis patients in human, the cellular sources of IL-33 in viral hepatitis remained obscure. Therefore, we aimed to investigate the expression of IL-33 in murine fulminant hepatitis induced by a Toll like receptor (TLR3) viral mimetic, poly(I:C) or by pathogenic mouse hepatitis virus (L2-MHV3). The administration of poly(I:C) plus D-galactosamine (D-GalN) in mice led to acute liver injury associated with the induction of IL-33 expression in liver sinusoidal endothelial cells (LSEC) and vascular endothelial cells (VEC), while the administration of poly(I:C) alone led to hepatocyte specific IL-33 expression in addition to vascular IL-33 expression. The hepatocyte-specific IL-33 expression was down-regulated in NK-depleted poly(I:C) treated mice suggesting a partial regulation of IL-33 by NK cells. The CD1d KO (NKT deficient) mice showed hepatoprotection against poly(I:C)-induced hepatitis in association with increased number of IL-33 expressing hepatocytes in CD1d KO mice than WT controls. These results suggest that hepatocyte-specific IL-33 expression in poly(I:C) induced liver injury was partially dependent of NK cells and with limited role of NKT cells. In parallel, the L2-MHV3 infection in mice induced fulminant hepatitis associated with up-regulated IL-33 expression as well as pro-inflammatory cytokine microenvironment in liver. The LSEC and VEC expressed inducible expression of IL-33 following L2-MHV3 infection but the hepatocyte-specific IL-33 expression was only evident between 24 to 32h of post infection. In conclusion, the alarmin cytokine IL-33 was over-expressed during fulminant hepatitis in mice with LSEC, VEC and hepatocytes as potential sources of IL-33.

Coxsackievirus B3 (CVB3) variants H3 and H310A1 differ by a single nonconserved amino acid in the VP2 capsid region. C57Bl/6 mice infected with the H3 virus develop myocarditis correlating with activation of T cells expressing the Vγ4 T cell receptor chain. Infecting mice with H310A1 activates natural killer T (NKT; mCD1d-tetramer(+) TCRβ(+)) cells, but not Vγ4 T cells, and fails to induce myocarditis. H310A1 infection preferentially activates M2 alternatively activated macrophage and CD4(+)FoxP3 (T regulatory) cells, whereas CD4(+)Th1 (IFN-γ(+)) cells are suppressed. By contrast, H3 virus infection activates M1 proinflammatory and CD4(+)Th1 cells, but not T regulatory cells. The M1 macrophage show significantly increased CD1d expression compared to M2 macrophage. The ability of NKT cells to suppress myocarditis was shown by adoptive transfer of purified NKT cells into H3-infected NKT knockout (Jα18 knockout) mice, which inhibited cardiac inflammation and increased T regulatory cell response. Cardiac virus titers were equivalent in all mouse strains indicating that neither Vγ4 nor NKT cells participate in control of virus infection. These data show that NKT and Vγ4 cells cross-regulate T regulatory cell responses during CVB3 infections and are the primary factor determining viral pathogenesis in this mouse model., (Copyright © 2013 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Chronic inappropriate immune activation is the central defect-driving loss of CD4(+) T helper cells and progression to AIDS in persons with HIV-1 infection, but the mechanisms remain controversial. We examined key regulatory invariant receptor natural killer T (iNKT) cells in the gut, the largest reservoir of lymphocytes and a key arena of HIV-1 pathogenesis. In healthy control persons, the anti-inflammatory CD4(+) iNKT-cell subset predominated over the pro-inflammatory CD4(-) iNKT-cell subset in the gut, but not in the blood, compartment. HIV-1 infection resulted in a preferential loss of this anti-inflammatory CD4(+) iNKT-cell subset within the gut. The degree of loss of the CD4(+) iNKT-cell subset in the gut, but not in the blood, correlated to the systemic immune activation and exhaustion that have been linked to disease progression. These results suggest a potentially important contribution of gut iNKT-cell imbalance in determining the systemic immune activation that is the hallmark of HIV-1 pathogenesis.

iNKT cells recognize lipid antigens, such as α-GalCer, presented in complex with CD1d expressed by DCs. Exposure of DCs to HIV-1 can lead to productive infection, and it was demonstrated recently that HIV-1 inhibits CD1d surface expression in an apparent mode of immune evasion. However, studies of the interaction between T cells, including iNKT cells and HIV-infected DCs in vitro, are hampered by the low frequency of productive infection in DCs. Here, we demonstrate the utility of full-length HIV-1 modified to express eGFP to address this problem. This virus allowed identification of single, rare productively infected cells in a mixed DC population by fluorescence microscopy and enabled detailed studies of the interaction of such cells with individual iNKT cells. iNKT cell responses to α-GalCer presented by HIV-1-positive and -negative DCs were quantified by intracellular IFN-γ staining in iNKT cells forming conjugates with DCs. Whereas complex formation was observed between iNKT cells and uninfected and infected DCs, only iNKT cells in contact with uninfected DCs produced IFN-γ. This microscopy assay, based on full-length HIV-1 modified to express eGFP, thus allows detailed evaluation of HIV-1 immune-evasion mechanisms in rare virus-infected live DCs.

Epstein-Barr virus (EBV)-associated natural killer (NK)/T-cell lymphomas show a geographical predilection for Asian and South American populations and are rare in Western countries. They predominantly occur in extranodal sites, including the nasal or paranasal areas, and less frequently in the localized nodal lesion. Most of the tumor cells exhibit a cytotoxic phenotype, characterized primarily by the expression of granzyme B and perforin. EBV is usually detected in tumor cells by using EBV-encoded small RNA in situ hybridization (EBER), suggesting that EBV plays an important role in lymphomagenesis. In this chapter, we have described 2 diseases: 1) extranodal NK/T-cell lymphoma, nasal type (ENKL), representative of extranodal EBV-associated NK/T-cell lymphoma; and 2) nodal cytotoxic molecule-positive EBV-positive peripheral T-cell lymphoma, not specified type (CM + EBV + PTCL-N), representative of nodal lymphoma. Both ENKL and nodal CM + EBV + PTCL-N are intractable to standard chemotherapy. Although ENKL is sensitive to radiotherapy, it shows a poorer response to chemotherapeutic agents than other lymphomas because of P-glycoprotein expression. P-glycoprotein is a product of the multidrug resistance (MDR1) gene, which is a major cause of the refractoriness of malignant lymphomas to conventional chemotherapeutic regimens containing anthracycline. l-asparaginase-containing regimens such as SMILE (steroid, methotrexate, ifosfamide, l-asparaginase, and etoposide) are effective for ENKL. Evaluation of effective chemotherapy for nodal CM + EBV + PTCL-N is ongoing., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

There is evidence indicating that invariant Natural Killer T (iNKT) cells play an important role in defense against influenza A virus (IAV). However, the effect of inhibitory receptor, programmed death-1 (PD-1), and its ligands, programmed death ligand (PD-L) 1 and 2 on iNKT cells in protection against IAV remains to be elucidated. Here we investigated the effects of these co-stimulatory molecules on iNKT cells in the response to influenza. We discovered that compare to the wild type, PD-L1 deficient mice show reduced sensitivity to IAV infection as evident by reduced weight loss, decreased pulmonary inflammation and cellular infiltration. In contrast, PD-L2 deficient mice showed augmented weight loss, pulmonary inflammation and cellular infiltration compare to the wild type mice after influenza infection. Adoptive transfer of iNKT cells from wild type, PD-L1 or PD-L2 deficient mice into iNKT cell deficient mice recapitulated these findings. Interestingly, in our transfer system PD-L1(-/-)-derived iNKT cells produced high levels of interferon-gamma whereas PD-L2(-/-)-derived iNKT cells produced high amounts of interleukin-4 and 13 suggesting a role for these cytokines in sensitivity to influenza. We identified that PD-L1 negatively regulates the frequency of iNKT cell subsets in the lungs of IAV infected mice. Altogether, these results demonstrate that lack of PD-L1 expression by iNKT cells reduces the sensitivity to IAV and that the presence of PD-L2 is important for dampening the deleterious inflammatory responses after IAV infection. Our findings potentially have clinical implications for developing new therapies for influenza.

The immune system plays a major role in protecting the host against viral infection. Rapid initial protection is conveyed by innate immune cells, while adaptive immunity (including T lymphocytes) requires several days to develop, yet provides high specificity and long-lasting memory. Invariant natural killer T (iNKT) cells are an unusual subset of T lymphocytes, expressing a semi-invariant T cell receptor together with markers of the innate NK cell lineage. Activated iNKT cells can exert direct cytolysis and can rapidly release a variety of immune-polarizing cytokines, thereby regulating the ensuing adaptive immune response. iNKT cells recognize lipids in the context of the antigen-presenting molecule CD1d. Intriguingly, CD1d-restricted iNKT cells appear to play a critical role in anti-viral defense: increased susceptibility to disseminated viral infections is observed both in patients with iNKT cell deficiency as well as in CD1d- and iNKT cell-deficient mice. Moreover, viruses have recently been found to use sophisticated strategies to withstand iNKT cell-mediated elimination. This review focuses on CD1d-restricted lipid presentation and the strategies viruses deploy to subvert this pathway.

Herpes simplex viruses (HSVs) are prevalent human pathogens that establish latency in human neuronal cells and efficiently evade the immune system. It has been a major medical challenge to eradicate them and, despite intensive efforts, an effective vaccine is not available. We previously showed that upon infection of antigen-presenting cells, HSV type 1 (HSV-1) rapidly and efficiently downregulates the major histocompatibility complex class I-like antigen-presenting molecule, CD1d, and potently inhibits its recognition by CD1d-restricted natural killer T (NKT) cells. It suppresses CD1d expression primarily by inhibiting its recycling to the cell surface after endocytosis. We identify here the viral glycoprotein B (gB) as the predominant CD1d-interacting protein. gB initiates the interaction with CD1d in the endoplasmic reticulum and stably associates with it throughout CD1d trafficking. However, an additional HSV-1 component, the serine-threonine kinase US3, is required for optimal CD1d downregulation. US3 expression in infected cells leads to gB enrichment in the trans-Golgi network (TGN) and enhances the relocalization of both gB and CD1d to this compartment, suggesting that following internalization CD1d is translocated from the endocytic pathway to the TGN by its association with gB. Importantly, both US3 and gB are required for efficient inhibition of CD1d antigen presentation and NKT cell activation. In summary, our results suggest that HSV-1 uses gB and US3 to rapidly inhibit NKT cell function in the initial antiviral response.

A wealth of evidence supports the essential contributions of mast cells (MCs) to immune defense against bacteria and parasites; however, the role of MCs in viral infections has not been defined. We now report that rodent, monkey, and human MCs are able to detect dengue virus (DENV), a lymphotropic, enveloped, single-stranded, positive-sense RNA virus that results in MC activation and degranulation. We observe that the response of MCs to DENV also involves the activation of antiviral intracellular host response pathways, melanoma differentiation-associated gene 5 (MDA5) and retinoic acid inducible gene 1 (RIG-I), and the de novo transcription of cytokines, including TNF-α and IFN-α, and chemokines, such as CCL5, CXCL12, and CX3CL1. This multifaceted response of MCs to DENV is consequential to the containment of DENV in vivo because, after s.c. infection, MC-deficient mice show increased viral burden within draining lymph nodes, which are known to be targeted organs during DENV spread, compared with MC-sufficient mice. This containment of DENV is linked to the MC-driven recruitment of natural killer and natural killer T cells into the infected skin. These findings support expanding the defined role of immunosurveillance by MCs to include viral pathogens.

Background: Extranasal natural killer (NK)/T-cell lymphoma and aggressive NK-cell leukemia are strongly associated with Epstein-Barr virus (EBV) and most often occur in middle-aged individuals. Overlap between these 2 diagnoses is rare. In addition, pathologic findings for these 2 diagnoses are typically notable for necrosis, apoptosis, angioinvasion, and angiodestruction., Observations: We describe a 15-year-old male adolescent who had painful subcutaneous nodules and plaques over his anterior thighs, shins, and lower abdomen while receiving anti-tumor necrosis factor therapy with infliximab. He also was noted to have pulmonary nodules, liver nodules, hepatosplenomegaly, thrombocytopenia, and transaminitis. A skin biopsy revealed atypical small to intermediate-sized EBV-positive lymphoid cells of NK-cell origin infiltrating the subcutaneous adipose tissue, mimicking subcutaneous T-cell lymphoma. Similar atypical EBV-positive lymphocytes were noted in the bone marrow, liver, stomach, and colon. This patient had a rapidly fatal disease course., Conclusions: We report a unique clinical and histological presentation most consistent with an extranasal NK/T-cell lymphoma and aggressive NK-cell leukemia overlap, although our case may represent a disease entity completely new to the literature. In addition, we report the first case to our knowledge of an EBV-positive NK/T-cell lymphoma developing in the setting of tumor necrosis factor inhibitor therapy., (©2011 American Medical Association. All rights reserved.)

Replication-defective recombinant adenoviruses are the most widely studied replication-defective vectors for the potential treatment of inherited human diseases. However, broad clinical application of replication-defective adenoviruses in gene therapy is being hindered by the induction of vigorous innate and adaptive immune responses against the vector that cause deleterious effects in the liver. V(alpha)14 invariant natural killer T cells (V(alpha)14iNKT cells) are thymus-derived innate T cells at the interface between the two arms of the immune response and provide full engagement of host defense. The pathophysiological role of intrahepatic V(alpha)14iNKT cells during replication-defective adenovirus infection is not known and is the main focus of our study. Our data showed that intrahepatic V(alpha)14iNKT cells were activated in response to adenovirus infection to induce significant levels of hepatic chemokine (C-C motif) ligand 5 (CCL5) and subsequent liver toxicity. Moreover, intrahepatic CCL5 production was selectively reduced by V(alpha)14iNKT cell deficiency. In vivo studies utilizing CCL5-deficient mice or V(alpha)14iNKT cell-deficient mice demonstrated that CCL5 deficiency or V(alpha)14iNKT cell deficiency was associated with reduced liver pathology. Similar results were seen after blocking the biological effects of the CCL5 receptors. In conclusion, we have identified an important proinflammatory role for activated intrahepatic V(alpha)14iNKT cells in positively influencing hepatic CCL5 production to promote acute liver inflammation and injury. Therefore, our findings highlight the blockade of CCL5 interaction with a cognate receptor(s) as an important potential strategy to alleviate liver pathology associated with replication-defective adenovirus infection.

NKT cells are known to play a role against certain microbial infections, including malaria and HIV, two major global infectious diseases. NKT cells exhibit either protective or pathogenic role against malaria. They are depleted by HIV infection and have a direct pathogenic role against many opportunistic infections common in end-stage AIDS. This review discusses the various features of the interaction between NKT cells and malaria parasites and HIV, and the potential to harness this interaction for therapeutic and vaccine strategies.

The pathogenesis of HIV-1 infection is a complex process in which Natural Killer (NK) and Natural Killer T (NKT) cells play an important role. NKT cells express markers for NK cells and a TCR of the conventional T cells and recognize lipid antigens presented by the non-polymorphic CD1 molecule. CD1d-restricted type I NKT cells express an invariant TCR and can recognize αGalCer, whereas a major subset of type II NKT expressing diverse TCR can recognize a self-glycolipid, sulfatide. It has been shown that CD4+ type I NKT cells are infected by HIV-1 and decreased in HIV-1-infected individuals. However, their exact role in HIV-1 infection as well as the biology and function of the type II NKT cell subset in HIV-1 infection and disease progression are not known. Our earlier studies have shown that activation of CD1d-restricted type II NKT cells by sulfatide and their interactions with plasmacytoid dendritic (pDC) and myeloid dendritic (mDC) cells result in anergy induction in type I NKT cells in several models. Here we used SCID-Hu (Thy/Liv) animals, co-implanted with human fetal liver and thymus, and found that these implants contain both type I and type II NKT cells, CD161+CD3+ NKT cells, NK cells and dendritic cells during HIV-infection. We found that the administration of sulfatide (bi-weekly, 20 μg/animal, i.p.) in SCID-Hu animals inhibits HIV-1 replication more efficiently than treatment with the nucleoside analog reverse transcriptase inhibitor, AZT. Virus replication was lowered significantly up to 4-8 weeks post infection. Furthermore sulfatide administration also resulted in significant retention of hematopoeisis that is lost during HIV-1 infection. Advantageously, sulfatide administration itself was not associated with anemia or bone marrow suppression, that are severe side effects of HAART. Since the CD1d-mediated immune pathway is highly conserved between rodents and humans, sulfatide treatment may represent a novel HLA-independent approach for intervention of HIV-1 pathogenesis.

Morbidity and mortality associated with viral infections increase with age, although the underlying mechanisms are unclear. Here, we investigated whether aging alters inflammatory responses during systemic viral infection and thereby contributes to virus-induced death. We found that infection of aged mice with systemic herpes viruses led to rapid increases in serum IL-17, neutrophil activation, and mortality due to hepatocyte necrosis. In contrast, all young mice survived infection, displaying weaker IL-17 induction and neutrophil activation. Natural killer T (NKT) cells isolated from the livers of aged mice produced more IL-17 than did young cells, and adoptively transferred aged NKT cells induced liver injury in young mice impaired in viral control. Importantly, IL-17 neutralization or neutrophil depletion during viral infection reduced liver damage and prevented death of aged mice. These results demonstrate that, during systemic viral infection, aging alters the host-pathogen interaction to overproduce IL-17, contributing to liver injury and death.

Invariant NK T (iNKT) cells influence the response to viral infections, although the mechanisms are poorly defined. In this study we show that these innate-like lymphocytes secrete IFN-gamma upon culture with CpG oligodeoxynucleotide-stimulated dendritic cells (DCs) from mouse bone marrow. This requires TLR9 signaling and IL-12 secretion by the activated DCs, but it does not require CD1d expression. iNKT cells also produce IFN-gamma in response to mouse CMV infection. Their mechanism of mouse CMV detection is quite similar to that of CpG, requiring both TLR9 signaling and IL-12 secretion, while the need for CD1d expression is relatively minor. Consequently, iNKT cells have the ability to respond to a variety of microbes, including viruses, in an Ag-independent manner, suggesting they may play a broad role in antipathogen defenses despite their limited TCR repertoire.

Objective: To investigate the expression of matrix metalloproteinase 9 (MMP9) in mucosal natural killer/T cell and mature T cell lymphomas and its relation to Epstein-Barr virus (EBV) infection., Methods: The expression of MMP9 and EBV-encoded RNA (EBER) were detected by immunohistochemistry and in situ hybridization in 59 cases of mucosal natural killer/T cell and mature T cell lymphomas., Results: The positivity rates of MMP9 and EBERs were 83.05% and 72.88% respectively. The positivity rate of EBERs was correlated with histopathological subtype (P<0.05), but not with clinical stage, vascular invasion or the patients' survival time (P>0.05). The expression level of MMP9 was not correlated with the clinical stage, vascular invasion or survival time (P>0.05). No significant correlation was found between MMP9 expression and EBV infection., Conclusion: EBV may play an important role in the development of mucosal natural killer/T cell and mature T cell lymphomas and promote disease progression by up-regulating MMP9 expression indirectly. Elimination of EBV infection may be helpful to prevent the development of lymphoma.