Therapeutic Effects of Insulin-Producing Human Umbilical Cord-Derived Mesenchymal Stem Cells in a Type 1 Diabetes Mouse Model.

In patients with type 1 diabetes (T1D), compromised pancreatic ß-cell functions are compensated through daily insulin injections or the transplantation of pancreatic tissue or islet cells. However, both approaches are associated with specific challenges. The transplantation of mesenchymal stem cells (MSCs) represents a potential alternative, as MSCs have tissue-forming capacity and can be isolated from various tissues. The human umbilical cord (hUC) is a good source of freely available MSCs, which can be collected through pain-free, non-invasive methods subject to minimal ethical concerns. We sought to develop a method for the in vitro generation of insulin-producing cells (IPCs) using MSCs. We examined the potential therapeutic uses and efficacy of IPCs generated from hUC-derived MSCs (hUC-IPCs) and human adipose tissue (hAD)-derived MSCs (hAD-IPCs) through in vitro experiments and streptozotocin (STZ)-induced C57BL/6 T1D mouse models. We discovered that compared to hAD-IPCs, hUC-IPCs exhibited a superior insulin secretion capacity. Therefore, hUC-IPCs were selected as candidates for T1D cell therapy in mice. Fasting glucose and intraperitoneal glucose tolerance test levels were lower in hUC-IPC-transplanted mice than in T1D control mice and hAD-IPC-transplanted mice. Our findings support the potential use of MSCs for the treatment of T1D.

Chitinase 3-like 1 protein plays a critical role in respiratory syncytial virus-induced airway inflammation.

BACKGROUND: Chitinase 3-like 1 protein (CHI3L1) (YKL-40 in humans and breast regression protein [BRP]-39 in mice) is required for optimal allergen sensitization and Th2 inflammation in various chronic inflammatory diseases including asthma. However, the role of CHI3L1 in airway inflammation induced by respiratory viruses has not been investigated. The aim of this study was to investigate the relationship between CHI3L1 and airway inflammation caused by respiratory syncytial virus (RSV) infection. METHODS: We measured YKL-40 levels in human nasopharyngeal aspirate (NPA) from hospitalized children presenting with acute respiratory symptoms. Wild-type (WT) and BRP-39 knockout (KO) C57BL/6 mice were inoculated with live RSV (A2 strain). Bronchoalveolar lavage fluid and lung tissue samples were obtained on day 7 after inoculation to assess lung inflammation, airway reactivity, and expression of cytokines and BRP-39. RESULTS: In human subjects, YKL-40 and IL-13 levels in NPA were higher in children with RSV infection than in control subjects. Expression of BRP-39 and Th2 cytokines, IL-13 in particular, was increased following RSV infection in mice. Airway inflammation caused by RSV infection was reduced in BRP-39 KO mice as compared to WT mice. Th2 cytokine levels were not increased in the lungs of RSV-infected BRP-39 KO mice. BRP-39 regulated M2 macrophage activation in RSV-infected mice. Additionally, treatment with anti-CHI3L1 antibody attenuated airway inflammation and Th2 cytokine production in RSV-infected WT mice. CONCLUSION: These findings suggest that CHI3L1 could contribute to airway inflammation induced by RSV infection. CHI3L1 could be a potential therapeutic candidate for attenuating Th2-associated immunopathology during RSV infection.

Hepatitis C virus impairs natural killer cell activity via viral serine protease NS3.

Hepatitis C virus (HCV) infection is characterized by a high frequency of chronic cases owing to the impairment of innate and adaptive immune responses. The modulation of natural killer (NK) cell functions by HCV leads to an impaired innate immune response. However, the underling mechanisms and roles of HCV proteins in this immune evasion are controversial, especially in the early phase of HCV infection. To investigate the role of HCV nonstructural proteins especially NS3 in the impairment of NK functions, NK cells were isolated from the PBMCs by negative selection. To assess the direct cytotoxicity and IFN-γ production capability of NK cells, co-cultured with uninfected, HCV-infected, HCV-NS3 DNA-transfected Huh-7.5, or HCV-NS replicon cells. To determine the effect of an NS3 serine protease inhibitor, HCV-infected Huh-7.5 cells were treated with BILN-2061. Then, NK cells were harvested and further co-cultured with K-562 target cells. NK cell functions were analyzed by flow cytometry and enzyme-linked immunosorbent assay. When co-cultured with HCV-infected Huh-7.5 cells, the natural cytotoxicity and IFN-γ production capability of NK cells were significantly reduced. NK cell functions were inhibited to similar levels upon co-culture with HCV-NS replicon cells, NS3-transfected cells, and HCV-infected Huh-7.5 cells. These reductions were restored by BILN-2061-treatment. Furthermore, BILN-2061-treatment significantly increased degranulation against K-562 target cells and IFN-γ productivity in NK cells. Consistent with these findings, the expression levels of activating NK cell receptors, such as NKp46 and NKp30, were also increased. In HCV-infected cells, the serine protease NS3 may play a role in the abrogation of NK cell functions in the early phase of infection through downregulation of NKp46 and NKp30 receptors on NK cells. Together, these results suggest that NS3 represents a novel drug target for the treatment of HCV infections.

Natural killer cells in hepatitis C: Current progress.

Patients infected with the hepatitis C virus (HCV) are characterized by a high incidence of chronic infection, which results in chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. The functional impairment of HCV-specific T cells is associated with the evolution of an acute infection to chronic hepatitis. While T cells are the important effector cells in adaptive immunity, natural killer (NK) cells are the critical effector cells in innate immunity to virus infections. The findings of recent studies on NK cells in hepatitis C suggest that NK cell responses are indeed important in each phase of HCV infection. In the early phase, NK cells are involved in protective immunity to HCV. The immune evasion strategies used by HCV may target NK cells and might contribute to the progression to chronic hepatitis C. NK cells may control HCV replication and modulate hepatic fibrosis in the chronic phase. Further investigations are, however, needed, because a considerable number of studies observed functional impairment of NK cells in chronic HCV infection. Interestingly, the enhanced NK cell responses during interferon-α-based therapy of chronic hepatitis C indicate successful treatment. In spite of the advances in research on NK cells in hepatitis C, establishment of more physiological HCV infection model systems is needed to settle unsolved controversies over the role and functional status of NK cells in HCV infection.

Reduction of the CD16(-)CD56bright NK cell subset precedes NK cell dysfunction in prostate cancer.

BACKGROUND: Natural cytotoxicity, mediated by natural killer (NK) cells plays an important role in the inhibition and elimination of malignant tumor cells. To investigate the immunoregulatory role of NK cells and their potential as diagnostic markers, NK cell activity (NKA) was analyzed in prostate cancer (PCa) patients with particular focus on NK cell subset distribution. METHODS: Prospective data of NKA and NK cell subset distribution patterns were measured from 51 patients initially diagnosed with PCa and 54 healthy controls. NKA was represented by IFN-γ levels after stimulation of the peripheral blood with Promoca®. To determine the distribution of NK cell subsets, PBMCs were stained with fluorochrome-conjugated monoclonal antibodies. Then, CD16(+)CD56(dim) and CD16(-)CD56(bright) cells gated on CD56(+)CD3(-) cells were analyzed using a flow-cytometer. RESULTS: NKA and the proportion of CD56(bright) cells were significantly lower in PCa patients compared to controls (430.9 pg/ml vs. 975.2 pg/ml and 2.3% vs. 3.8%, respectively; p<0.001). Both tended to gradually decrease according to cancer stage progression (p for trend = 0.001). A significantly higher CD56(dim)-to-CD56(bright) cell ratio was observed in PCa patients (41.8 vs. 30.3; p<0.001) along with a gradual increase according to cancer stage progression (p for trend = 0.001), implying a significant reduction of CD56(bright) cells in relation to the alteration of CD56(dim) cells. The sensitivity and the specificity of NKA regarding PCa detection were 72% and 74%, respectively (best cut-off value at 530.9 pg/ml, AUC = 0.786). CONCLUSIONS: Reduction of CD56(bright) cells may precede NK cell dysfunction, leading to impaired cytotoxicity against PCa cells. These observations may explain one of the mechanisms behind NK cell dysfunction observed in PCa microenvironment and lend support to the development of future cancer immunotherapeutic strategies.