Effects Of HIV Or HCV Infection On Cytokine Secretion By PDC-NK Cell System

Objective To investigate the effects of HIV infection or HCV infection on cytokine production of plasmacytoiddendritic cells(pDC)-natural killer(NK)cell system,under the conditions of unactivation or activation via TLR9 pathway agonist ODN2216.To provide new information for the understanding of the interaction mechanism(s)of two types of natural immune cells,pDC and NK cells,as well as the effects of viral infections on this interaction.Methods Immunomagnetic separation was used to isolate pDCs and NK cells,and two types of cells were mixed to establish an in vitro pDC-NK cell co-culture system.The interaction of two types types of natural immune cells was determined by measure of cytokines produced from pDC-NK cell system under the condition of activation with TLR9 agonist ODN2216 in vitro.The pDC and NK cells were also isolated from healthy subjects.HIV-infected and HCV-infected patients,respectively.Suspension array technology was used to detect the production of cytokines in pDC-NK system in vitro among different groups.The effects of HIV infection or HCV infection on the pDC-NK cell system were analyzed by comparing with the situation in healthy population.Results1.Effects of HIV infection or HCV infection on the function of pDCs1.1 pDCs from healthy subjects could be activated in vitro and released a large number of cytokines including IFN-a,TNF-a,TNF-?.However,the levels of IL-12 and IL-18 had no significant changes.1.2 HCV infection could activate pDCs in vivo,and HCV infection did not inhibit the TLR9 pathway of pDCs in vitro.pDCs of HCV group could be activated by TLR9 agonist ODN2216.Under the condition of unactivation,pDCs from HCV-infected patients exhibited higher levels of 5 cytokines(IFN-a,IL-12,EL-18,TNF-?,TNF-?)compared to healthy control subjects.in vitro activation experiment showed that the levels of 2 cytokines(IFN-?,TNF-?)in pDCs activation group were significantly higher than those in pDCs unactivated group.Meanwhile,the levels of 3 pDC-producing cytokines(TNF-a,IL-12,IL18)in HCV ODN2216 activation group were significantly higher than those in healthy activation group(p<0.05).1.3 HIV infection could activate pDCs in vivo,but HIV infection inhibited TLR9 pathway of pDCs in vitro.The production of IFN-? from pDCs was significantly suppressed by HIV infection.Under the condition of unactivation,pDCs from HIV-infected patients exhibited higher levels of 5 cytokines(IFN-a,IL-12,IL-18,TNF-a,TNF-?)compared to healthy control subjects.in vitro activation experiment showed that the levels of 5 cytokines(IFN-a,IL-12,IL-18,TNF-?,TNF-?)in pDCs activation group were not significantly changed compared to pDCs unactivated group.Meanwhile,the level of IFN-a in HIV ODN2216 stimulation group was significantly lower than that in healthy activation group(p<O.05).2.TLR9 agonist ODN2216 could not directly activate NK cells.Blood samples of healthy subjects,HIV-infected and HCV-infected patients were collected.NK cells were isolated and treated with or without ODN2216 in vitro.The expression of 3 cytotoxic factors(IFN-y,Granzyme-B,FasL)in NK cells was detected,and there was no significant difference between these groups.There was also no significant difference in the expression of cytotoxic factors between ODN2216-treated and untreated NK cells within each population.3.Effects of HIV infection or HCV infection on pDC-NK cell system3.1 NK cells could be activated via ODN2216-activated pDCs in vitro.pDC-NK cell system from healthy subjects was treated with ODN2216 in vitro.The levels of 5 NK cell-producing cytokines,including IFN-y,IL-5,IL-10,IL-13,and GM-CSF were significantly up-regulated,and the difference was statistically significant between ODN2216-treated and untreated groups.3.2 HCV infection had a certain inhibitory effect on pDC-NK cell system.Although NK cells in HCV group could be still activated by ODN2216-activated pDCs.However,the activation level in HCV group was lower than healthy control group.Under the condition of unactivation,the levels of 5 NK-producing cytokines(IFN-?,IL-10,GM-CSF,MIP-1a and RANTES)in HCV group were significantly lower than those in healthy control group,and the difference was statistically significant.When the pDC-NK cell system was activated with ODN2216,the levels of 4 cytokines(IL-5,IL-13,MIP-1?,MIP-1?)were up-regulated when compared with HCV unactivated group,and the difference was statistically significant.Meanwhile,the levels of 7 NK-producing cytokines(IFN-?,IL-5,IL-10,GM-CSF,MIP-la,MIP-1?,RANTES)in HCV ODN2216 activiation group were significantly lower than those in healthy ODN2216 activiation group.3.3 HIV infection could inhibit the in vitro activation of pDC-NK cell system.Under the condition of unactivation,the levels of 7 NK-producing cytokines(IFN-?,IL-10,GM-CSF,MIP-1?,MIP-1?,RANTES)in HIV group were not significantly changed compared to healthy control group,except up-expressed IL-5 in HIV group.When the pDC-NK cell system was activated with ODN2216,the levels of 5 cytokines(IFN-?,IL-10,IL-13,GM-CSF,RANTES)in HIV ODN2216 activiation group were significantly lower than those in healthy ODN2216 activation group.Conclusion This study has successfully established an in vitro pDC-NK cell co-culture system.In this cell system,NK cells could be activated by ODN2216-activated pDCs through pDCs' TLR-9 pathway in vitro,which was evidenced by activated NK cells could secret a variety of cytokines.This study further explored the effects of HIV infection or HCV infection on the pDC-NK cell system.The results show that HIV infection or HCV infection could induce pDCs to an activated state in vivo.However,HIV infection could damage in vitro TLR-9 activation of pDCs,and thus impair pDC-NK cell interaction.HCV infection,on the contrary,had no significant effect on TLR-9 activation of pDCs in vitro,however,it also inhibits the in vitro activation of the pDC-NK cell system.This inhibitory effect may be achieved by HCV impairment on NK cells.Taken together,these results indicate that HIV infection or HCV infection could inhibit the function of pDC-NK cell system,but the inhibitory mechanism is different in two types of viral infections.