AIM2
Interferon-inducible protein AIM2 (Absent in melanoma 2)
Publications[править]
Inducing tumour-specific adaptive immunity, such as cytotoxic T lymphocyte (CTL) response, can result in promising antitumour effect against several human malignancies, especially in combination with immune checkpoint blockade strategies. However, little is known whether activation of innate immunity can lead to direct tumoricidal effect. Here, we develop a papilloma pseudovirus-based oral immunotherapeutic approach that shows strong tumoricidal effects in the gut, resulting in an almost tripled lifespan of Apc mice (an animal model of human intestinal tumorigenesis). Mechanistically, these pseudoviruses activate the NLRP3 and AIM2 inflammasomes, leading to caspase-1-mediated tumour regression that is dependent on neither cytotoxic T lymphocytes nor humoral immune response. Blocking caspase-1 activation abrogated the therapeutic effects of the pseudoviruses. Thus, targeting innate immune sensors in tumours by the pseudoviruses might represent a strategy to treat intestinal tumours.
MeSH Terms
- Animals
- Caspase 1
- Female
- Humans
- Immunity, Innate
- Inflammasomes
- Intestinal Neoplasms
- Longevity
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Mutant Strains
- Papillomaviridae
- Survival Analysis
- T-Lymphocytes, Cytotoxic
Human aging is associated with remodeling of the immune system. While most studies on immunosenescence have focused on adaptive immunity, the effects of aging on innate immunity are not well understood. Here, we investigated whether aging affects cytokine responses to a wide range of well-defined pattern recognition receptor (PRR) ligands, such as ligands for Toll-like receptors (TLRs), C-type lectin receptors (CLRs), NOD-like receptors (NLRs), retinoic-acid-inducible gene-I like receptors (RLRs) and the cytosolic DNA sensor absent in melanoma 2 (AIM2). Blood was collected from 16 young (20-39 years) and 18 elderly (60-84 years) healthy participants. Pro-inflammatory cytokine (TNF-α, IL-1β, IL-6, and IL-8) production in a whole blood assay (WBA) after stimulation with TLR ligands (Pam3csk4, poly(I:C), LPS, CpG), CLR ligand (β-glucan), NLR ligand (MDP), RLR ligands (5'ppp-dsDNA and poly(I:C)/lyovec) and the AIM2 ligand (poly(dA:dT) was assessed by ELISA. TLR2 and TLR4 expression by leukocytes and monocytes was determined by flow-cytometry. Expression of AIM2 by peripheral blood mononuclear cells (PBMC) was assessed by qRT-PCR and Western blot. Cytokine responses to Pam3csk4, poly(I:C) and CpG, β-glucan, MDP, 5'ppp-dsDNA and poly(I:C)/lyovec were comparable between young and old participants. We observed a higher IL-8 response following stimulation of elderly blood samples with the TLR4 ligand LPS, which was associated with higher proportions of TLR4 expressing monocytes. Interestingly, stimulation of whole blood cells with the AIM2 ligand poly(dA:dT) resulted in significantly lower cytokine responses in old participants. Moreover, these lower cytokine responses were associated with lower AIM2 protein expression and activation in PBMC of old participants. Our findings reveal an age-dependent reduction of AIM2 expression and activation which may explain reduced cytokine responses to the cytosolic DNA mimic poly(dA:dT) in healthy elderly individuals. Reduced AIM2-mediated sensing with age may contribute to increased vulnerability to bacterial or viral infections in the elderly.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Cytokines
- DNA-Binding Proteins
- Female
- Humans
- Male
- Middle Aged
- Monocytes
- Signal Transduction
- Toll-Like Receptors
- Young Adult
Keywords
- Absent in melanoma 2
- Aging
- Human
- Innate immunity
- Pattern recognition receptors
Chronic low-grade inflammation is considered a driver of many age-related disorders, including vascular diseases (inflammaging). Inhibition of autophagic capacity with ageing was postulated to generate a pro-inflammatory condition via activation of inflammasomes, a group of Interleukin-1 activating intracellular multi-protein complexes. We thus investigated gene expression of inflammasome components in PBMC of 77 vascular patients (age 22-82) in association with age. Linear regression of real-time qRT-PCR data revealed a significant positive association of gene expression of each of the inflammasome components with age (Pearson correlation coefficients: AIM2: r = 0.245; P = 0.032; NLRP3: r = 0.367; P = 0.001; ASC (PYCARD): r = 0.252; P = 0.027; CASP1: r = 0.296; P = 0.009; CASP5: r = 0.453; P = 0.00003; IL1B: r = 0.247; P = 0.030). No difference in gene expression of AIM2, NLRP3, ASC CASP1, and CASP5 was detected between PBMC of patients with advanced atherosclerosis and other vascular patients, whereas IL1B expression was increased in PBMC of the latter group (P = 0.0005). The findings reinforce the systemic pro-inflammatory phenotype reported in elderly by demonstrating an increased phase-1 activation of inflammasomes in PBMC of vascular patients.
Keywords
- AIM2
- Aging
- Atherosclerosis
- Inflammation
- NLRP3
- Vascular disease
The molecular changes underlying the higher risk of chronic inflammatory disorders during aging remain incompletely understood. Molecular variations in the innate immune response related to recognition and interaction with microbes at mucosal surfaces could be involved in aging-related inflammation. We developed an ontology analysis of 20 nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) and seven inflammasome-related genes (IRGs) in healthy and inflamed/periodontitis oral mucosal tissues from young, adolescent, adult, and aged non-human primates (Macaca mulatta) using the GeneChip(®) Rhesus Macaque Genome array. Validation of some of the significant changes was done by quantitative reverse transcription-polymerase chain reaction. The expression of NLRB/NAIP, NLRP12, and AIM2 increased with aging in healthy mucosa whereas NLRC2/NOD2 expression decreased. Although higher expression levels of some NLRs were generally observed with periodontitis in adult mucosal tissues (e.g. NLRB/NAIP, NLRP5, and NLRX1), various receptors (e.g. NLRC2/NOD2 and NLRP2) and the inflammasome adaptor protein ASC, exhibited a significant reduction in expression in aged periodontitis tissues. Accordingly, the expression of NLR-activated innate immune genes, such as HBD3 and IFNB1, was impaired in aged but not adult periodontitis tissues. Both adult and aged tissues showed significant increase in interleukin-1β expression. These findings suggest that the expression of a subset of NLRs appears to change with aging in healthy oral mucosa, and that aging-related oral mucosal inflammation could involve an impaired regulation of the inflammatory and antimicrobial response associated with downregulation of specific NLRs and IRGs.
MeSH Terms
- Aging
- Animals
- Carrier Proteins
- Female
- Gene Expression
- Immunity, Innate
- Inflammasomes
- Interleukin-1beta
- Macaca mulatta
- Male
- Mouth Mucosa
- NLR Proteins
- Neuronal Apoptosis-Inhibitory Protein
- Periodontitis
- RNA, Messenger
- Real-Time Polymerase Chain Reaction
- Signal Transduction
Keywords
- Aging
- NOD-like receptors
- inflammasome
- innate immunity
- oral mucosa
Ageing is a complex and multifactorial process characterized by the accumulation of many forms of damage at the molecular, cellular, and tissue level with advancing age. Ageing increases the risk of the onset of chronic inflammation-associated diseases such as cancer, diabetes, stroke, and neurodegenerative disease. In particular, ageing and cancer share some common origins and hallmarks such as genomic instability, epigenetic alteration, aberrant telomeres, inflammation and immune injury, reprogrammed metabolism, and degradation system impairment (including within the ubiquitin-proteasome system and the autophagic machinery). Recent advances indicate that damage-associated molecular pattern molecules (DAMPs) such as high mobility group box 1, histones, S100, and heat shock proteins play location-dependent roles inside and outside the cell. These provide interaction platforms at molecular levels linked to common hallmarks of ageing and cancer. They can act as inducers, sensors, and mediators of stress through individual plasma membrane receptors, intracellular recognition receptors (e.g., advanced glycosylation end product-specific receptors, AIM2-like receptors, RIG-I-like receptors, and NOD1-like receptors, and toll-like receptors), or following endocytic uptake. Thus, the DAMP Hypothesis is novel and complements other theories that explain the features of ageing. DAMPs represent ideal biomarkers of ageing and provide an attractive target for interventions in ageing and age-associated diseases.
MeSH Terms
- Aging
- Animals
- Humans
- Neoplasms
- Receptors, Pattern Recognition
Keywords
- Ageing
- Biomarker
- Cancer
- Damage-associated molecular pattern (DAMP) molecules
- Longevity
- Receptor