ABSTRACT
The extension of life span driven by 40% caloric restriction (CR) in rodents causes trade-offs in growth, reproduction, and immune defense that make it difficult to identify therapeutically relevant CR-mimetic targets. We report that about 14% CR for 2 years in healthy humans improved thymopoiesis and was correlated with mobilization of intrathymic ectopic lipid. CR-induced transcriptional reprogramming in adipose tissue implicated pathways regulating mitochondrial bioenergetics, anti-inflammatory responses, and longevity. Expression of the gene Pla2g7 encoding platelet activating factor acetyl hydrolase (PLA2G7) is inhibited in humans undergoing CR. Deletion of Pla2g7 in mice showed decreased thymic lipoatrophy, protection against age-related inflammation, lowered NLRP3 inflammasome activation, and improved metabolic health. Therefore, the reduction of PLA2G7 may mediate the immunometabolic effects of CR and could potentially be harnessed to lower inflammation and extend the health span.
Subject(s)
1-Alkyl-2-acetylglycerophosphocholine Esterase/genetics , Adipose Tissue/metabolism , Caloric Restriction , Immune System/physiology , Inflammation , Thymus Gland/immunology , 1-Alkyl-2-acetylglycerophosphocholine Esterase/metabolism , Adult , Aging , Animals , Down-Regulation , Energy Metabolism , Female , Humans , Inflammasomes/metabolism , Longevity , Lymphopoiesis , Macrophages/immunology , Macrophages/metabolism , Male , Mice , Middle Aged , Mitochondria/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Thermogenesis , Thymus Gland/anatomy & histology , TranscriptomeABSTRACT
Germline mutations in STK11, which encodes the tumor suppressor liver kinase B1 (LKB1), promote Peutz-Jeghers syndrome (PJS), a cancer predisposition syndrome characterized by the development of gastrointestinal (GI) polyps. Here, we report that heterozygous deletion of Stk11 in T cells (LThet mice) is sufficient to promote GI polyposis. Polyps from LThet mice, Stk11+/- mice, and human PJS patients display hallmarks of chronic inflammation, marked by inflammatory immune-cell infiltration, signal transducer and activator of transcription 3 (STAT3) activation, and increased expression of inflammatory factors associated with cancer progression [interleukin 6 (IL-6), IL-11, and CXCL2]. Targeting either T cells, IL-6, or STAT3 signaling reduced polyp growth in Stk11+/- animals. Our results identify LKB1-mediated inflammation as a tissue-extrinsic regulator of intestinal polyposis in PJS, suggesting possible therapeutic approaches by targeting deregulated inflammation in this disease.
Subject(s)
Adenomatous Polyps/genetics , Peutz-Jeghers Syndrome/genetics , Protein Serine-Threonine Kinases/genetics , Stomach Neoplasms/genetics , T-Lymphocytes/immunology , AMP-Activated Protein Kinases , Adenomatous Polyps/immunology , Adenomatous Polyps/pathology , Animals , Chemokine CXCL2/genetics , Gene Deletion , Gene Expression , Humans , Inflammation/genetics , Inflammation/immunology , Inflammation/pathology , Interleukin-11/genetics , Interleukin-6/genetics , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , Peutz-Jeghers Syndrome/immunology , Peutz-Jeghers Syndrome/pathology , STAT3 Transcription Factor/metabolism , Signal Transduction , Stomach Neoplasms/immunology , Stomach Neoplasms/pathologyABSTRACT
Mammals are coinfected by multiple pathogens that interact through unknown mechanisms. We found that helminth infection, characterized by the induction of the cytokine interleukin-4 (IL-4) and the activation of the transcription factor Stat6, reactivated murine γ-herpesvirus infection in vivo. IL-4 promoted viral replication and blocked the antiviral effects of interferon-γ (IFNγ) by inducing Stat6 binding to the promoter for an important viral transcriptional transactivator. IL-4 also reactivated human Kaposi's sarcoma-associated herpesvirus from latency in cultured cells. Exogenous IL-4 plus blockade of IFNγ reactivated latent murine γ-herpesvirus infection in vivo, suggesting a "two-signal" model for viral reactivation. Thus, chronic herpesvirus infection, a component of the mammalian virome, is regulated by the counterpoised actions of multiple cytokines on viral promoters that have evolved to sense host immune status.
