Article

Age-Associated Decrease in TLR Function in Primary Human Dendritic Cells Predicts Influenza Vaccine Response

Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT 06520, USA.
The Journal of Immunology (Impact Factor: 4.92). 03/2010; 184(5):2518-27. DOI: 10.4049/jimmunol.0901022
Source: PubMed

ABSTRACT

We evaluated TLR function in primary human dendritic cells (DCs) from 104 young (age 21-30 y) and older (> or =65 y) individuals. We used multicolor flow cytometry and intracellular cytokine staining of myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) and found substantial decreases in older compared with young individuals in TNF-alpha, IL-6, and/or IL-12 (p40) production in mDCs and in TNF-alpha and IFN-alpha production in pDCs in response to TLR1/2, TLR2/6, TLR3, TLR5, and TLR8 engagement in mDCs and TLR7 and TLR9 in pDCs. These differences were highly significant after adjustment for heterogeneity between young and older groups (e.g., gender, race, body mass index, number of comorbid medical conditions) using mixed-effect statistical modeling. Studies of surface and intracellular expression of TLR proteins and of TLR gene expression in purified mDCs and pDCs revealed potential contributions for both transcriptional and posttranscriptional mechanisms in these age-associated effects. Moreover, intracellular cytokine production in the absence of TLR ligand stimulation was elevated in cells from older compared with young individuals, suggesting a dysregulation of cytokine production that may limit further activation by TLR engagement. Our results provide evidence for immunosenescence in DCs; notably, defects in cytokine production were strongly associated with poor Ab response to influenza immunization, a functional consequence of impaired TLR function in the aging innate immune response.

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    • "Research on TLRs has focused on their immune function and has been extended to aging and cancer (Qian et al., 2012; Rakoff-Nahoum and Medzhitov, 2009). TLR signaling is defective in macrophages or dendritic cells during normal aging (Dunston and Griffiths, 2010; Panda et al., 2010). However, our group and Qian's group recently showed that TLR5 in peritoneal macrophages and monocytes from older donors, respectively are conserved during aging (Lim et al., 2015; Qian et al., 2012) . "
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    ABSTRACT: Toll-like receptor 5 (TLR5) is a specific receptor for microbial flagellin and is one of the most well-known receptors in the TLR family. We reported previously that TLR5 signaling is well maintained during aging and that caveolin-1 may be involved in TLR5 signaling in aged macrophages through direct interactions. Therefore, it is important to clarify whether caveolin-1/TLR5 interactions affect TLR5 expression during aging. To assess the effect of caveolin-1 on TLR5, we analyzed TLR5 expression in senescent fibroblasts and aged tissues expressing high levels of caveolin-1. As expected, TLR5 mRNA and protein expression was well maintained in senescent fibroblasts and aged tissues, whereas TLR4 mRNA and protein were diminished in those cells and tissues. To determine the mechanism of caveolin-1-dependent TLR5 expression, we examined TLR5 expression in caveolin-1 deficient mice. Interestingly, TLR5 mRNA and protein levels were decreased dramatically in tissues from caveolin-1 knockout mice. Moreover, overexpressed caveolin-1 in vitro enhanced TLR5 mRNA through the MAPK pathway and prolonged TLR5 protein half-life through direct interaction. These results suggest that caveolin-1 may play a crucial role in maintaining of TLR5 by regulating transcription systems and increasing protein half-life.
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    • "For example, it has been reported that DCs and monocytes obtained from old subjects produced more cytokines than those form adults (Alvarez-Rodriguez et al., 2012; Hearps et al., 2012). On the other hand, others have reported no change or lower production in old compared to adult subjects (Gon et al., 1996; van Duin et al., 2007b; Panda et al., 2010). In the case of PBMCs, studies have yielded increased production of cytokines and chemokines [including CCL3, CCL5, IL-6, TNFa, and IL-1b (Fagiolo et al., 1993; Pulsatelli et al., 2000)] in the elderly population, which is contrasting to our results. "
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    ABSTRACT: Aging leads to dysregulation of multiple components of the immune system that results in increased susceptibility to infections and poor response to vaccines in the aging population. The dysfunctions of adaptive B and T cells are well documented, but the effect of aging on innate immunity remains incompletely understood. Using a heterogeneous population of peripheral blood mononuclear cells (PBMCs), we first undertook transcriptional profiling and found that PBMCs isolated from old individuals (≥ 65 years) exhibited a delayed and altered response to stimulation with TLR4, TLR7/8, and RIG-I agonists compared to cells obtained from adults (≤ 40 years). This delayed response to innate immune agonists resulted in the reduced production of pro-inflammatory and antiviral cytokines and chemokines including TNFα, IL-6, IL-1β, IFNα, IFNγ, CCL2, and CCL7. While the major monocyte and dendritic cell subsets did not change numerically with aging, activation of specific cell types was altered. PBMCs from old subjects also had a lower frequency of CD40+ monocytes, impaired up-regulation of PD-L1 on monocytes and T cells, and increased expression of PD-L2 and B7-H4 on B cells. The defective immune response to innate agonists adversely affected adaptive immunity as TLR-stimulated PBMCs (minus CD3 T cells) from old subjects elicited significantly lower levels of adult T-cell proliferation than those from adult subjects in an allogeneic mixed lymphocyte reaction (MLR). Collectively, these age-associated changes in cytokine, chemokine and interferon production, as well as co-stimulatory protein expression could contribute to the blunted memory B- and T-cell immune responses to vaccines and infections. © 2015 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.
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    • "Other investigators have challenged this conclusion and assert that viral RNA is active in the split vaccine [13]. In humans, Panda et al. identified an age-associated decrease in TLR function that can predict in vivo serological responses in SV immunized subjects [14]. It still remains unclear whether this association is causal or if the SV influenza vaccine can engage TLRs. "
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