Defective pro-IL-1β responses in macrophages from aged mice
© Ramirez et al.; licensee BioMed Central Ltd. 2012
Received: 20 July 2012
Accepted: 5 December 2012
Published: 11 December 2012
Cytokines regulated by the inflammasome pathway have been extensively implicated in various age-related immune pathologies. We set out to elucidate the contribution of the nod-like receptor protein 3 (NLRP3) inflammasome pathway to the previously described deficiencies in IL-1β production by macrophages from aged mice. We examined the production of pro-IL-1β and its conversion into IL-1β as two separate steps and compared these cytokine responses in bone marrow derived macrophages from young (6–8 weeks) and aged (18–24 months) C57BL/6 mice.
Relative to macrophages from young mice, macrophages from aged mice produced less pro-IL-1β after TLR4 stimulation with LPS. However upon activation of the NLRP3 inflammasome with ATP, macrophages from young and aged mice were able to efficiently convert and secrete intracellular pro-cytokines as functional cytokines.
Lower levels of IL-1β production are a result of slower and lower overall production of pro-IL-1β in macrophages from aged mice.
KeywordsAgeing Macrophages Aged mice NLRP3 Inflammasome IL-1β
Immunosenescence has been associated with altered levels of pro and anti-inflammatory cytokines such as IL-1β, TNF-α, IL-6, IL-10, TGF-β and Prostaglandin E2 in the blood of aged individuals [1–3]. These aberrant cytokine responses are thought to contribute to the inability of the elderly to mount appropriate immune responses to pathogens, vaccines and self antigen . Macrophages from aged mice have a lower production of cytokines when activated with IFN-γ or LPS  and decreased TNF-α and IL-6 production when infected with Porphyromonas gingivalis compared to macrophages from young mice. Furthermore bone marrow derived macrophages (BMM) from aged mice secrete less IL-1β compared to BMM from young mice when stimulated with LPS for 6 hours . IL-1β and IL-18 have been associated with a wide variety of age associated diseases including rheumatoid arthritis, multiple sclerosis, atherosclerosis, gout, immunosenescence and greater susceptibility to infectious disease [8–12] thus highlighting the importance of inflammasome regulated cytokines in the aging process [13, 14].
The inflammasome is a multiprotein complex that regulates IL-1β and IL-18 secretion by signal recognition via TLRs in combination with NLR or PYHN sensor proteins [15, 16]. There are two distinct regulatory steps in the production of active IL-1β. The first step is the production of the biologically inert precursor pro-IL-1β in response to stimulation by a TLR ligand. The second step is the processing of the immature form of the cytokine into its active form by the inflammasome complex. The NLRs are a large family of cytosolic sensors and the best studied one is NLRP3 which forms part of a family of inflammasomes important in detecting many pathogens including influenza virus, Candida albicans, Saccharomyces cerevisiae and Staphylococcus aureus. While previous groups have shown that cells from aged mice produce lower levels of IL-1β, it is unclear whether these defects lie primarily at the priming stage and/or maturation stage of these critical cytokines. The success of immunomodulatory intervention to enhance or dampen aberrant inflammatory cytokine responses in aged individuals will likely depend on identifying and targeting key molecules in inflammatory pathways including the inflammasome.
Our results taken together indicate that BMM from aged mice may have a significant defect downstream of TLR4 signaling which leads to a reduced output of inflammasome associated cytokines IL-1β and IL-18. BMM from aged mice have a functional IL-1β response but with different kinetics of production as well as a lower overall level of production compared to BMM from young mice. These findings are consistent with the research from other groups which have shown lower secretion of TLR4 dependent cytokines in macrophages from aged mice, which are not dependent upon inflammasome processing, such as TNF-α or IL-6 .
Stout-Delgado et al. have recently shown that nigericin, an NLRP3 inducer used in favor of TLR agonists, potentiated IL-1β responses to influenza A virus in aged mice resulting in improved survival and better outcome of infection . Our data indicate that this strategy takes advantage of the fully functional inflammasome response to strong NLRP3 agonists like nigericin or ATP by myeloid cells in aged mice. Our study has implications to understanding immunomodulatory strategies that are needed to boost waning immunity in the elderly . Successful application of these strategies will require controlled stimulation of protective immune responses without exacerbating the release of potentially harmful proinflammatory cytokines.
All experiments were performed in accordance with guidelines of the Institutional Animal Care and Use Committee of the University of Massachusetts Medical School and the recommendations in the Guide for the Care and Use of Laboratory Animals (Institute of Laboratory Animal Resources, National Research Council, National Academy of Sciences, 1996).
Bone marrow derived macrophages
Enzyme linked immune-sorbent assay
Geometric mean fluorescence intensity
Macrophage colony stimulating factor
Nod like receptor
Nod-like receptor protein 3
Standard error of the mean
Transforming growth factor beta
Tumor necrosis factor alpha
Toll like receptor.
This work was supported by grants GM054060, AI093752 and U19 AI57319 from the National Institutes of Health and by the NERCE fellowship NIH/NIAID AI057159 (VAR).
- Krabbe KS, Pedersen M, Bruunsgaard H: Inflammatory mediators in the elderly. Exp Gerontol. 2004, 39 (5): 687-699. 10.1016/j.exger.2004.01.009.View ArticlePubMedGoogle Scholar
- Bruunsgaard H, Pedersen M, Pedersen BK: Aging and proinflammatory cytokines. Curr Opin Hematol. 2001, 8 (3): 131-136. 10.1097/00062752-200105000-00001.View ArticlePubMedGoogle Scholar
- Salminen A, Huuskonen J, Ojala J, Kauppinen A, Kaarniranta K, Suuronen T: Activation of innate immunity system during aging: NF-kB signaling is the molecular culprit of inflamm-aging. Ageing Res Rev. 2008, 7 (2): 83-105. 10.1016/j.arr.2007.09.002.View ArticlePubMedGoogle Scholar
- Ginaldi L, Loreto MF, Corsi MP, Modesti M, De Martinis M: Immunosenescence and infectious diseases. Microbes Infect. 2001, 3 (10): 851-857. 10.1016/S1286-4579(01)01443-5.View ArticlePubMedGoogle Scholar
- Higashimoto Y, Fukuchi Y, Shimada Y, Ishida K, Ohata M, Furuse T, Shu C, Teramoto S, Matsuse T, Sudo E: The effects of aging on the function of alveolar macrophages in mice. Mech Ageing Dev. 1993, 69 (3): 207-217. 10.1016/0047-6374(93)90024-L.View ArticlePubMedGoogle Scholar
- Shaik-Dasthagirisaheb YB, Kantarci A, Gibson FC: Immune response of macrophages from young and aged mice to the oral pathogenic bacterium Porphyromonas gingivalis. Immun Ageing. 2010, 7: 15-10.1186/1742-4933-7-15.PubMed CentralView ArticlePubMedGoogle Scholar
- Chelvarajan RL, Liu Y, Popa D, Getchell ML, Getchell TV, Stromberg AJ, Bondada S: Molecular basis of age-associated cytokine dysregulation in LPS-stimulated macrophages. J Leukoc Biol. 2006, 79 (6): 1314-1327. 10.1189/jlb.0106024.View ArticlePubMedGoogle Scholar
- Goldbach-Mansky R: Immunology in clinic review series; focus on autoinflammatory diseases: update on monogenic autoinflammatory diseases: the role of interleukin (IL)-1 and an emerging role for cytokines beyond IL-1. Clin Exp Immunol. 2012, 167 (3): 391-404. 10.1111/j.1365-2249.2011.04533.x.PubMed CentralView ArticlePubMedGoogle Scholar
- Hooper-van Veen T, Schrijver HM, Zwiers A, Crusius JB, Knol DL, Kalkers NF, Laine ML, Barkhof F, Pena AS, Polman CH: The interleukin-1 gene family in multiple sclerosis susceptibility and disease course. Mult Scler. 2003, 9 (6): 535-539. 10.1191/1352458503ms974oa.View ArticlePubMedGoogle Scholar
- Rader DJ: IL-1 and atherosclerosis: a murine twist to an evolving human story. J Clin Investig. 2012, 122 (1): 27-30. 10.1172/JCI61163.PubMed CentralView ArticlePubMedGoogle Scholar
- Kingsbury SR, Conaghan PG, McDermott MF: The role of the NLRP3 inflammasome in gout. J Inflamm Res. 2011, 4: 39-49.PubMed CentralPubMedGoogle Scholar
- Strowig T, Henao-Mejia J, Elinav E, Flavell R: Inflammasomes in health and disease. Nature. 2012, 481 (7381): 278-286. 10.1038/nature10759.View ArticlePubMedGoogle Scholar
- Dinarello CA: Interleukin 1 and interleukin 18 as mediators of inflammation and the aging process. Am J Clin Nutr. 2006, 83 (2): 447S-455S.PubMedGoogle Scholar
- Cavallone L, Bonafe M, Olivieri F, Cardelli M, Marchegiani F, Giovagnetti S, Di Stasio G, Giampieri C, Mugianesi E, Stecconi R: The role of IL-1 gene cluster in longevity: a study in Italian population. Mech Ageing Dev. 2003, 124 (4): 533-538. 10.1016/S0047-6374(03)00033-2.View ArticlePubMedGoogle Scholar
- Jin C, Flavell RA: Molecular mechanism of NLRP3 inflammasome activation. J Clin Immunol. 2010, 30 (5): 628-631. 10.1007/s10875-010-9440-3.View ArticlePubMedGoogle Scholar
- Rathinam VA, Vanaja SK, Fitzgerald KA: Regulation of inflammasome signaling. Nat Immunol. 2012, 13 (4): 333-342. 10.1038/ni.2237.PubMed CentralView ArticlePubMedGoogle Scholar
- Bryant C, Fitzgerald KA: Molecular mechanisms involved in inflammasome activation. Trends Cell Biol. 2009, 19 (9): 455-464. 10.1016/j.tcb.2009.06.002.View ArticlePubMedGoogle Scholar
- Gomez CR, Karavitis J, Palmer JL, Faunce DE, Ramirez L, Nomellini V, Kovacs EJ: Interleukin-6 contributes to age-related alteration of cytokine production by macrophages. Mediators Inflamm. 2010, 2010: 475139-PubMed CentralPubMedGoogle Scholar
- Stout-Delgado HW, Vaughan SE, Shirali AC, Jaramillo RJ, Harrod KS: Impaired NLRP3 inflammasome function in elderly mice during influenza infection is rescued by treatment with nigericin. J Immunol. 2012, 188 (6): 2815-2824. 10.4049/jimmunol.1103051.PubMed CentralView ArticlePubMedGoogle Scholar
- Fulop T, Fortin C, Lesur O, Dupuis G, Kotb JR, Lord JM, Larbi A: The innate immune system and ageing: what is the contribution to immunosenescence. Open Longev Sci. 2012, 6: 121-10.2174/1876326X01206010121. 132View ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.