Single-cell analysis reveals that stochasticity and paracrine signaling control interferon-alpha production by plasmacytoid dendritic cells.
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ABSTRACT:
SUBMITTER: Wimmers F
PROVIDER: S-EPMC6102223 | biostudies-literature | 2018 Aug
REPOSITORIES: biostudies-literature
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Project description:The observation that the T-bet transcription factor allows tissue-specific upregulation of intracellular osteopontin (Opn-i) in plasmacytoid dendritic cells (pDCs) suggests that Opn might contribute to the expression of interferon-alpha (IFN-alpha) in those cells. Here we show that Opn deficiency substantially reduced Toll-like receptor 9 (TLR9)-dependent IFN-alpha responses but spared expression of transcription factor NF-kappaB-dependent proinflammatory cytokines. Shortly after TLR9 engagement, colocalization of Opn-i and the adaptor molecule MyD88 was associated with induction of transcription factor IRF7-dependent IFN-alpha gene expression, whereas deficient expression of Opn-i was associated with defective nuclear translocation of IRF7 in pDCs. The importance of the Opn-IFN-alpha pathway was emphasized by its essential involvement in cross-presentation in vitro and in anti-herpes simplex virus 1 IFN-alpha response in vivo. The finding that Opn-i selectively coupled TLR9 signaling to expression of IFN-alpha but not to that of other proinflammatory cytokines provides new molecular insight into the biology of pDCs.
| S-EPMC3725256 | biostudies-other
Project description:The large family of human type I interferon (IFN) includes 13 distinct subtypes of IFN-alpha, all utilizing a single type I IFN receptor. Many viruses have created evasion strategies to disable this cytokine family, highlighting their importance in antiviral defense. It is unclear what advantage the presence of so many different IFN-alpha subtypes provides, but functional differences observed among individual IFN-alpha subtypes suggested that they might play distinct regulatory roles during an immune response. To determine whether IFN-alpha subtype responses differ depending on a particular type of insult and thus whether IFN-alpha subtype responses are flexible to adapt to distinct pathogen challenges, we developed a novel nested multiplex reverse transcriptase polymerase chain reaction assay with which we measured expression of all IFN-alpha subtypes by freshly isolated human plasmacytoid dendritic cells (pDCs), a main source of IFN-alpha following pathogen challenge. Collectively our data show a remarkable stability in the relative magnitude and the kinetics of induction for each IFN-alpha subtype produced by pDC. Although various stimuli used, A-, B- and C-class CpGs, live and heat-inactivated influenza viruses and the TLR7 agonist R837 affected the overall magnitude of the response, each IFN-alpha subtype was induced at statistically similar relative levels and with similar kinetics, thereby revealing a great degree of rigidity in the IFN-alpha response pattern of pDC. These data are most consistent with the induction of optimized ratios of IFN-alpha subtypes, each of which may have differing signaling properties or alternatively, a great degree of redundancy in the IFN-alpha response.
| S-EPMC2956691 | biostudies-literature
Project description:BackgroundToll-like receptor (TLR)-7-associated rhinovirus (RV) activation is involved in the pathogenesis of asthma. Plasmacytoid dendritic cells (pDCs) are the main interferon-α-producing cells against viruses.ObjectiveTo determine whether asthmatic patients and control subjects differ in terms of interferon-α expression in pDCs under TLR-7 or RV stimulation.MethodspDCs were identified in BDCA-2+ and HLA-DR+ peripheral blood mononuclear cells. Interferon-α expression of pDCs was analyzed after TLR-7 stimulation with or without interleukin 4 (IL-4)/IL-13 pretreatment. Interferon-α expression was also analyzed after RV stimulation over periods of 24, 48, or 96 h with or without IL-4 pretreatment. RV detection and molecular typing were assayed from throat swabs.ResultsFollowing TLR-7 stimulation, the expression of intracellular interferon-α was higher in the pDCs of normal subjects than those of asthmatic patients; however, pretreatment with IL-4 was shown to reduce this effect. After 48- and 96-h RV stimulation, we observed a notable increase in the production of interferon-α of pDCs in normal subjects but not in asthmatic patients. Baseline interferon-α expression in pDCs and the incidence of asthma exacerbation to emergency was higher among the 13% of patients identified as rhinovirus+ than among their RV counterparts.ConclusionOur study discovered the response to TLR-7 stimulation in pDCs was compromised and the sustainability of interferon-α expression to RV stimulation was reduced in pDCs of asthmatic patients, which provide further evidence of defective innate response and subspeciality to RV infection in asthma. The high exacerbation history founded in RV+ patients agrees with these findings. Further research is required for the modulatory effect of IL-4 on TLR-7 stimulated pDCs.
| S-EPMC7860612 | biostudies-literature
Project description:Acute kidney injury (AKI) is a common clinical complication associated with high mortality in patients. Immune cells and cytokines have recently been described to play essential roles in AKI pathogenesis. Plasmacytoid dendritic cells (pDCs) are a unique DC subset that specializes in type I interferon (IFN) production. Here, we showed that pDCs rapidly infiltrated the kidney in response to AKI and contributed to kidney damage by producing IFN-α. Deletion of pDCs using DTRBDCA2 transgenic (Tg) mice suppressed cisplatin-induced AKI, accompanied by marked reductions in proinflammatory cytokine production, immune cell infiltration and apoptosis in the kidney. In contrast, adoptive transfer of pDCs during AKI exacerbated kidney damage. We further identified IFN-α as the key factor that mediated the functions of pDCs during AKI, as IFN-α neutralization significantly attenuated kidney injury. Furthermore, IFN-α produced by pDCs directly induced the apoptosis of renal tubular epithelial cells (TECs) in vitro. In addition, our data demonstrated that apoptotic TECs induced the activation of pDCs, which was inhibited in the presence of an apoptosis inhibitor. Furthermore, similar deleterious effects of pDCs were observed in an ischemia reperfusion (IR)-induced AKI model. Clinically, increased expression of IFN-α in kidney biopsies was observed in kidney transplants with AKI. Taken together, the results of our study reveal that pDCs play a detrimental role in AKI via IFN-α.
| S-EPMC7852581 | biostudies-literature
Project description:MZB1 is an endoplasmic reticulum (ER)-resident protein that plays an important role in the humoral immune response by enhancing the interaction of the μ immunoglobulin (Ig) heavy chain with the chaperone GRP94 and by augmenting the secretion of IgM. Here, we show that MZB1 is also expressed in plasmacytoid dendritic cells (pDCs). Mzb1-/- pDCs have a defect in the secretion of interferon (IFN) α upon Toll-like receptor (TLR) 9 stimulation and a reduced ability to enhance B cell differentiation towards plasma cells. Mzb1-/- pDCs do not properly expand the ER upon TLR9 stimulation, which may be accounted for by an impaired activation of ATF6, a regulator of the unfolded protein response (UPR). Pharmacological inhibition of ATF6 cleavage in stimulated wild type pDCs mimics the diminished IFNα secretion by Mzb1-/- pDCs. Thus, MZB1 enables pDCs to secrete high amounts of IFNα by mitigating ER stress via the ATF6-mediated UPR.
| S-EPMC7736851 | biostudies-literature
Project description:To determine the potential consequences of plasmacytoid dendritic cell (pDC) accumulation in tissue sites observed in several autoimmune diseases, we measured type 1 interferon production from circulating human pDCs as a function of pDC concentration. The effects of interferon-alpha and blockade of the type 1 interferon receptor (IFNAR) on human pDC type 1 interferon and interferon-inducible transcription and protein production were measured. Human pDCs became far more efficient producers of interferon-alpha at concentrations beyond those normally present in blood, through an IFNAR-dependent mechanism. Extracellular interferon-alpha increased pDC production of type 1 interferons. The accumulation of pDCs in diseased tissue sites allows marked non-linear amplification of type 1 interferon production locally. The role of the IFNAR-dependent mechanism of interferon production by human pDCs is greater than previously suggested. IFNAR blockade has potential for diminishing type 1 interferon production by all human cells.
| S-EPMC2892243 | biostudies-literature
Project description:IntroductionPlasmacytoid dendritic cells (pDCs) constitutively express two members of the Toll-like receptor (TLR) family, TLR-9 and TLR-7, through which they can be stimulated to produce high levels of interferon (IFN)-?, a key mediator of the pathogenesis of systemic lupus erythematosus (SLE). Given the known efficacy of hydroxychloroquine (HCQ) in the treatment of SLE, we examined its ability to inhibit such pDC function in vivo.MethodsPeripheral blood mononuclear cells (PBMCs) from SLE subjects treated or not with HCQ and from healthy controls were stimulated with the TLR-9 agonist, CpG oligodeoxynucleotides (CpG-A ODN)-2216, and the TLR-7 agonist, imiquimod. The proportion of monocytes, B cells, myeloid dendritic cells, pDCs, and natural killer (NK) cells producing IFN-? and tumor necrosis factor alpha (TNF-?) was then analyzed by multiparameter flow cytometry.ResultsAfter TLR-9/7 stimulation in both SLE and healthy subjects, significant production of IFN-? and TNF-? was only observed in pDCs. TLR-7 and TLR-9 induced IFN-? and TNF-? production by pDCs from subjects with SLE was decreased relative to that found in controls (TLR-9/IFN-?, P < 0.0001; TLR-9/TNF-? P < 0.0001; TLR-7/TNF-? P = 0.01). TLR-9 and TLR-7 induced IFN-? and TNF-? production by pDCs was severely impaired in 36% (TLR-9) and 33% (TLR-7) of SLE subjects. In almost all cases, these subjects were being treated with HCQ (HCQ vs. no HCQ: impaired TLR-9/IFN-?, P = 0.0003; impaired TLR-7/IFN-?, P = 0.07; impaired TLR-9/TNF-?, P < 0.009; impaired TLR-7/TNF-?, P < 0.01).ConclusionsTreatment with HCQ is associated with impaired ability of pDCs from subjects with SLE to produce IFN-? and TNF-? upon stimulation with TLR-9 and TLR-7 agonists.
| S-EPMC3446541 | biostudies-literature
Project description:Type I IFN production is essential for innate control of acute viral infection; however, prolonged high-level IFN production is associated with chronic immune activation in HIV-infected individuals. Although plasmacytoid DCs (pDCs) are a primary source of IFN, the mechanisms that regulate IFN levels following the acute phase are unknown. We hypothesized that HIV-specific Ab responses regulate late IFN production. We evaluated the mechanism through which HIV-activated pDCs produce IFN as well as how both monoclonal HIV-specific Abs and Abs produced in natural HIV infection modulated normal pDC sensing of HIV. We found that HIV-induced IFN production required TLR7 signaling, receptor-mediated entry, fusion, and viral uncoating, but not endocytosis or HIV life cycle stages after uncoating. Abs directed against the HIV envelope that do not interfere with CD4 binding markedly enhanced the IFN response, irrespective of their ability to neutralize CD4+ T cell infection. Ab-mediated enhancement of IFN production required Fc ? receptor engagement, bypassed fusion, and initiated signaling through both TLR7 and TLR9, which was not utilized in the absence of Ab. Polyclonal Abs isolated from HIV-infected subjects also enhanced pDC production of IFN in response to HIV. Our data provide an explanation for high levels of IFN production and immune activation in chronic HIV infection.
| S-EPMC5707144 | biostudies-literature
Project description:IFN-I production is a characteristic of HIV/SIV primary infections. However, acute IFN-I plasma concentrations rapidly decline thereafter. Plasmacytoid dendritic cells (pDC) are key players in this production but primary infection is associated with decreased responsiveness of pDC to TLR 7 and 9 triggering. IFN? production during primary SIV infection contrasts with increased pDC death, renewal and dysfunction. We investigated the contribution of pDC dynamics to both acute IFN? production and the rapid return of IFN? concentrations to pre-infection levels during acute-to-chronic transition. Nine cynomolgus macaques were infected with SIVmac251 and IFN?-producing cells were quantified and characterized. The plasma IFN-I peak was temporally associated with the presence of IFN?(+) pDC in tissues but IFN-I production was not detectable during the acute-to-chronic transition despite persistent immune activation. No IFN?(+) cells other than pDC were detected by intracellular staining. Blood-pDC and peripheral lymph node-pDC both lost IFN?(-) production ability in parallel. In blood, this phenomenon correlated with an increase in the counts of Ki67(+)-pDC precursors with no IFN? production ability. In tissues, it was associated with increase of both activated pDC and KI67(+)-pDC precursors, none of these being IFN?(+) in vivo. Our findings also indicate that activation/death-driven pDC renewal rapidly blunts acute IFN? production in vivo: pDC sub-populations with no IFN?-production ability rapidly increase and shrinkage of IFN? production thus involves both early pDC exhaustion, and increase of pDC precursors.
| S-EPMC3907389 | biostudies-literature
Project description:BackgroundIt is well known that interferon (IFN)-alpha is important to the pathogenesis of systemic lupus erythematosus (SLE). However, several reports have indicated that the number of IFN-alpha producing cells are decreased or that their function is defective in patients with SLE. We studied the function of plasmacytoid dendritic cells (pDCs) under persistent stimulation of Toll-like receptor (TLR)9 via a TLR9 ligand (CpG ODN2216) or SLE serum.MethodsThe concentrations of IFN-alpha were determined in serum and culture supernatant of peripheral blood mononuclear cells (PBMCs) from SLE patients and healthy controls after stimulation with CpG ODN2216 or SLE serum. The numbers of circulating pDCs were analyzed by fluoresence-activated cell sorting analysis. pDCs were treated with CpG ODN2216 and SLE serum repeatedly, and levels of produced IFN-alpha were measured. The expression of IFN-alpha signature genes and inhibitory molecules of TLR signaling were examined in PBMCs from SLE patients and healthy control individuals.ResultsAlthough there was no significant difference in serum concentration of IFN-alpha and number of circulating pDCs between SLE patients and healthy control individuals, the IFN-alpha producing capacity of PBMCs was significantly reduced in SLE patients. Interestingly, the degree which TLR9 ligand-induced IFN-alpha production in SLE PBMCs was inversely correlated with the SLE serum-induced production of IFN-alpha in healthy PMBCs. Because repeated stimulation pDCs with TLR9 ligands showed decreased level of IFN-alpha production, continuous TLR9 stimulation may lead to decreased production of IFN-alpha in SLE PBMCs. In addition, PBMCs isolated from SLE patients exhibited higher expression of IFN-alpha signature genes and inhibitory molecules of TLR signaling, indicating that these cells had already undergone IFN-alpha stimulation and had become desensitized to TLR signaling.ConclusionWe suggest that the persistent presence of endogenous IFN-alpha inducing factors induces TLR tolerance in pDCs of SLE patients, leading to impaired production of IFN-alpha.
| S-EPMC2453773 | biostudies-literature