Natural Killer Cell Function In Patients Research Articles

TIGIT Signaling Pathway Regulates Natural Killer Cell Function in Chronic Hepatitis B Virus Infection

Background and ObjectivePersistent infection of hepatitis B virus (HBV) and liver damage in immune active chronic hepatitis B (CHB) could be partly due to the overreaction of natural killer (NK) cells, including pro-inflammatory cytokine secretion and cytotoxicity. An immunosuppressive receptor, T-cell immunoglobulin and immunoreceptor tyrosine–based inhibitory motif (ITIM) domain (TIGIT) is specifically expressed in NK cells. This study aims to investigate the role of the TIGIT signaling pathway in regulating NK cell functions in patients with CHB.MethodWe comparatively assessed the expression of TIGIT in NK cells of patients with immune active CHB (CHB-IA), carriers of immune control chronic HBV (CHB-IC), and healthy controls (HCs), and then explored mechanisms of the TIGIT signaling pathway in regulating NK cell-mediated liver injury by different molecular assessments.ResultThe expression of TIGIT in NK cells was enhanced in CHB-IC but was reduced in CHB-IA compared with the HC group. In patients with CHB-IA, the expression of TIGIT was inversely correlated with intensity of the liver damage. Moreover, TIGIT-NK cells show higher IFN-γ secretion capability, degranulation activity, and cytotoxicity but lower apoptosis than TIGIT+ NK cells. Blockade of the TIGIT pathway with anti-TIGIT antibody increased NK cell function, while activation of the TIGIT pathway with TIGIT Fc and CD155 Fc chimera protein down-regulated NK cell function.ConclusionOur data showed that the TIGIT signaling pathway participates in NK cell impairment, which could be used as a new therapeutic target to protect patients with chronic HBV infection from severe liver injury.

Veritable antiviral capacity of natural killer cells in chronic HBV infection: an argument for an earlier anti-virus treatment

BackgroundThere is limited information on innate immunity, especially natural killer (NK) cell function, in different chronic hepatitis B (CHB) stages. Therefore, we examined whether the clinical staging strategy accurately reflects veritable NK cell immunity.MethodsA total of 237 eligible CHB patients and 22 healthy controls were enrolled in our study. Demographic and clinical data were collected, and the CHB phases (immune active-IA, immune tolerant phase-IT, inactive CHB-IC, and grey zone-GZ) were classified according to the latest American Association for the Study of Liver Disease guidelines. Peripheral blood mononuclear cells from patients and healthy controls were tested for NK cell frequency, phenotype and function using flow cytometry.ResultsA significant decrease in activating receptor NKp44 and NKp46 expression and significant increase of exhaustion molecule Tim-3 expression were observed in NK cells from CHB patients. Reduced cytokine secretion and preserved or elevated cytotoxic function were also observed. Patients in the IT group exhibited comparable cytokine secretion and cytolytic capacity as age-matched IA patients. NK cell anti-viral functions were preserved in GZ patients. Some of the NK cell function in patients who were excluded from treatment by the current treatment guidelines was less compromised than patients who qualified for treatment.ConclusionOur findings provide evidence of veritable NK cell immunity during different natural history phases in treatment-naïve patients with chronic HBV Infection. Chronic HBV infection hindered NK cell function in CHB patients. However, the presumed IT and GZ statuses of CHB patients based on the clinical parameters may not accurately reflect the inner immune status of these patients and should be reconsidered. Some patients excluded from treatment by the current treatment guidelines may be able to be selected as candidates for treatment.

Ruxolitinib partially reverses functional natural killer cell deficiency in patients with signal transducer and activator of transcription 1 (STAT1) gain-of-function mutations

Natural killer (NK) cells are critical innate effector cells whose development is dependent on the Janus kinase-signal transducer and activator of transcription (STAT) pathway. NK cell deficiency can result in severe or refractory viral infections. Patients with STAT1 gain-of-function (GOF) mutations have increased viral susceptibility. We sought to investigate NK cell function in patients with STAT1 GOF mutations. NK cell phenotype and function were determined in 16 patients with STAT1 GOF mutations. NK cell lines expressing patients' mutations were generated with clustered regularly interspaced short palindromic repeats (CRISPR-Cas9)-mediated gene editing. NK cells from patients with STAT1 GOF mutations were treated invitro with ruxolitinib. Peripheral blood NK cells from patients with STAT1 GOF mutations had impaired terminal maturation. Specifically, patients with STAT1 GOF mutations have immature CD56dim NK cells with decreased expression of CD16, perforin, CD57, and impaired cytolytic function. STAT1 phosphorylation was increased, but STAT5 was aberrantly phosphorylated in response to IL-2 stimulation. Upstream inhibition of STAT1 signaling with the small-molecule Janus kinase 1/2 inhibitor ruxolitinib invitro and invivo restored perforin expression in CD56dim NK cells and partially restored NK cell cytotoxic function. Properly regulated STAT1 signaling is critical for NK cell maturation and function. Modulation of increased STAT1 phosphorylation with ruxolitinib is an important option for therapeutic intervention in patients with STAT1 GOF mutations.

Natural Killer Cells from Patients with Chronic Rhinosinusitis Have Impaired Effector Functions

Natural killer (NK) cells are multicompetent lymphocytes of the innate immune system that play a central role in host defense and immune regulation. Although increasing evidence suggests that innate immunity plays a key role in the pathogenesis of chronic rhinosinusitis (CRS), the role of NK cells in CRS has been poorly studied. This study aimed to characterize the peripheral blood NK cells from patients with CRS, and to compare the functions of these cells with those from non-CRS controls. The correlation between NK cell functional activity and prognosis was also assessed. Eighteen CRS patients and 19 healthy non-CRS controls were included. The patients with CRS were classified into two subgroups, namely a treatment-responsive group and recalcitrant group. NK cell degranulation was determined by measuring the cell surface expression of CD107a against 721.221 and K562 cells. Intracytoplasmic cytokine production was determined by flow cytometry. Compared to the controls, the NK cells of CRS group had an impaired ability to degranulate and to produce cytokines such as IFN-γ and TNF-α. The recalcitrant subgroup showed the most severe defects in NK cell effector functions. Moreover, the decreased NK cell functions in patients with CRS were associated with poor prognostic factors such as concomitant asthma and peripheral blood eosinophilia. NK cells, which were originally named for their ability to mediate spontaneous cytotoxicity towards diseased cells including infected cells, may play an important role in regulating the inflammatory process in CRS pathogenesis.

Expression of natural killer cell activating receptors in patients with chronic lymphocytic leukaemia

Recent advances in chronic lymphocytic leukaemia (CLL) treatment, more particularly through upfront use of anti-CD20 monoclonal antibodies, have prolonged patient progression-free survival. Nonetheless, apart from allogeneic stem cell transplantation, no curative treatment is available. One possible explanation for the lack of cure in CLL could be a defective immune anti-tumour response. As the result of abnormal HLA class I molecule expression, CLL cells escape from specific T-lymphocyte immunity but should be the target for the innate natural killer (NK) cell-mediated immune response. Defective NK cytotoxicity as the result of decreased expression of the natural cytotoxicity receptors (NCRs) NKp30/NCR3, NKp44/NCR2 and NKp46/NCR1 has been described in haematological malignancies such as acute myeloid leukaemia. This prompted us to focus our attention on NCR expression on NK cells from patients with CLL. Although we failed to detect any difference between CLL patients and healthy age-matched controls, a precise analysis of clinical data showed a correlation between decreased NCR expression and poor prognosis factors such as low haemoglobin level, high (>30×10(9) per litre) lymphocyte count or elevated C-reactive protein. Together, these observations support the rationale for restoration of normal NK cell functions in patients with CLL, putatively through the use of immune therapy protocols that already have demonstrated some benefit in acute myeloid leukaemia such as interleukin-2 plus histamine dihydrochloride.

Decreased NKG2D expression on NK cells correlates with impaired NK cell function in patients with gastric cancer

Although malignant diseases are known to be associated with immune suppression, the detailed mechanisms involved are still unknown. NKG2D is an activating cell surface receptor expressed by natural killer (NK) cells and CD8+ T cells, and the engagement of NKG2D is extremely important for NK cell activation. Although decreased NKG2D expression on NK cells is closely related to immune evasion by some cancers, the immunopathological importance of this phenomenon in gastric cancer patients remains unclear. NKG2D expression on NK cells was determined, using multicolor flow cytometry, to investigate the mechanisms responsible for immune evasion in gastric cancer patients. NKG2D expression on NK cells from gastric cancer patients was significantly lower than that in healthy controls. Also, NKG2D expression in advanced gastric cancer was significantly lower than that in early gastric cancer. NK cells from patients with lymph node metastasis expressed significantly lower levels of NKG2D than the NK cells from those without lymph node metastasis, and NKG2D expression on NK cells in gastric cancer tissue was significantly lower than that of circulating NK cells. NKG2D expression on NK cells obtained from cancer patients was restored after 48h in culture with RPMI containing 10% AB serum. Furthermore, NKG2D expression on NK cells obtained after surgery was significantly higher than that before surgery. Decreased NKG2D expression on NK cells may be one of the key mechanisms responsible for NK cell dysfunction in gastric cancer.

Decreased DAP12 expression in natural killer lymphocytes from patients with systemic lupus erythematosus is associated with increased transcript mutations

Decreased numbers of natural killer (NK) cells and impaired NK function have been reported in patients with systemic lupus erythematosus (SLE). Since DAP12 plays a pivotal role in activation of NK cells, we analyzed the expressions of DAP12 protein and mRNA in peripheral blood NK cells from patients with SLE. Both DAP12 protein and mRNA expressions in NK cells from the SLE patients were decreased compared with those in NK cells from normal subjects. Sequence analysis of DAP12 cDNA showed increased nucleotide mutations, including both nucleotide substitutions and deletions. In spite of the mRNA mutations, we found no mutations in genomic DNA, suggesting that mRNA was modified during or after transcription. Decreased expression of DAP12 in NK cells from the patients was accompanied by increased expression of ADAR1 (adenosine deaminase that acts on RNA transcripts) and by decreased expression of NKp44. These results suggest that abnormal expression of DAP12 molecules in NK cells may account for the impairment of NK cell function in patients with SLE.

Lack of Natural Killer Cell Augmentation in vitro by Human Interferon Gamma in a Subset of Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is a generalized connective tissue disorder characterized by fibrosis of skin and various viscera. Natural killer (NK) cells are a subset of lymphocytes that can lyse targets without prior sensitization. Few studies have tried to assess NK cell function in patients with SSc. To evaluate NK cell cytotoxicity in patients with SSc and to see the extent of its augmentation in vitro by human interferon (hIFN) gamma in the clinical subset of limited and diffuse cutaneous diseases, we evaluated 27 patients with SSc and 22 age- and sex-matched controls by 51Cr release assay. Fifteen patients had limited cutaneous disease (mean disease duration 6.2 +/- 2.7 years) and 12 diffuse cutaneous disease (mean disease duration 5.7 +/- 2.4 years). Patients with limited SSc had significantly higher baseline NK cell function than controls (p < 0.05) and the augmentation following in vitro stimulation with hIFN gamma was negligible. Patients with diffuse SSc had lower baseline NK cell cytotoxicity than controls but this was not statistically significant. Augmentation with hIFN gamma in this group was comparable to controls. This study suggests that NK cells may have a role in the pathophysiology of this disease.

Immune function in patients with chronic stable congestive heart failure

The objective of this study was to ascertain whether immune abnormalities were present in a group of patients with chronic stable heart failure at a time when sympathetic drive was not excessive. Elevated sympathetic tone not only plays an important role in the pathophysiologic characteristics of congestive heart failure but may also regulate certain aspects of immune function, which has been shown to be abnormal in patients with severe heart failure. Studies have indicated a high incidence of heterophil antibodies against constituents of the heart, the presence of antibody-mediated cytotoxicity against cultured heart cells, and a decrease in suppressor and natural killer-cell function in patients with idiopathic dilated cardiomyopathy. Lymphocytes were separated over a Ficoll-Hypaque gradient. Lymphocyte subtypes and well as interleukin-2 receptors were detected by means of mouse monoclonal antibodies conjugated with fluorescein or phycoerytherin, and immunofluorescence was measured with a flow cytometer. Mitogen proliferation was assessed by tritiated thymidine incorporation in the presence of either conconavalin A or tetanus toxoid. Serum was used in conjunction with iodine 125-labeled iodopindolol binding to rat cardiac membranes to attempt to detect β-receptor antibodies. In patients with ischemic ( n = 21) and idiopathic ( n = 16) cardiomyopathy, the norepinephrine levels were modestly elevated (idiopathic = 482 ± 70 pg/ml; ischemic = 501 ± 45 pg/ml) compared with control subjects without heart disease ( n = 10; norepinephrine = 252 ± 70 pg/ml). We found no differences in the number and subtypes of circulating lymphocytes in the three groups, and there was no serum inhibition of β-binding to rat cardiac membranes. Mitogen proliferation, as well as interleukin-2 receptor expression, was unaltered when lymphocytes from all patients with congestive heart failure were exposed to the nonspecific T-cell mitogen concanavalin A. Stimulation of lymphocytes over a wide range of concentrations with the specific T-cell antigen tetanus toxoid, however, revealed decreases in 3H-thymidine incorporation both in patients with ischemic and idiopathic cardiomyopathy compared with control subjects. We conclude that early in the course of heart failure, at a time when there are no alterations in circulating lymphocytes and no evidence of antibodies against the cardiac β-receptor, use of the specific T-cell antigen tetanus toxoid, but not the conventional mitogen concanavalin A, uncovers an abnormality in T-cell function both in patients with idiopathic and ischemic heart failure.

Study on lymphocyte subsets and NK cell function in patients with dilated cardiomyopathy.

An acquired defect or damage of a subpopulation of suppressor T lymphocytes is reported in connection with autoimmune diseases. In the present study, the role of immunity was examined in 7 patients with dilated cardiomyopathy (DCM). The frequency of lymphocyte subsets using monoclonal antibodies and natural killer (NK) cell activity was evaluated to determine whether DCM patients had lymphocyte abnormalities that would support the hypothesis that the pathological mechanism of DCM is an immune disturbance. The peripheral lymphocyte counts were significantly lower in patients with DCM and higher in patients with ischemic heart disease (IHD) than in normal controls (NC) (p less than 0.01). The percentage of T cells, B cells, OKT4 and OKT8 positive cells was not statistically different among the three groups studied here, whereas the percentage of T gamma cells was significantly reduced in DCM patients (p less than 0.05). NK cell functional activity as tested in DCM and IHD patients was frequently deficient (22.1 +/- 19.3% in DCM, 13.8 +/- 3.0% in IHD, 37.4 +/- 12.7% in NC). Our results suggest that an imbalance in cellular immune reactions partly explain the pathogenesis of DCM.