Targeting senescent cells alleviates obesity-induced metabolic dysfunction

Adipose tissue inflammation and dysfunction are associated with obesity-related insulin resistance and diabetes, but mechanisms underlying this relationship are unclear. Although senescent cells accumulate in adipose tissue of obese humans and rodents, a direct pathogenic role for these cells in the development of diabetes remains to be demonstrated. Here, we show that reducing senescent cell burden in obese mice, either by activating drug-inducible "suicide" genes driven by the p16Ink4a promoter or by treatment with senolytic agents, alleviates metabolic and adipose tissue dysfunction. These senolytic interventions improved glucose tolerance, enhanced insulin sensitivity, lowered circulating inflammatory mediators, and promoted adipogenesis in obese mice. Elimination of senescent cells also prevented the migration of transplanted monocytes into intra-abdominal adipose tissue and reduced the number of macrophages in this tissue. In addition, microalbuminuria, renal podocyte function, and cardiac diastolic function improved with senolytic therapy. Our results implicate cellular senescence as a causal factor in obesity-related inflammation and metabolic derangements and show that emerging senolytic agents hold promise for treating obesity-related metabolic dysfunction and its complications.

Identification of stable senescence-associated reference genes

Cellular senescence is a state of permanent cell cycle arrest activated in response to damaging stimuli. Many hallmarks associated with senescent cells are measured by quantitative real-time PCR (qPCR). As the selection of stable reference genes for interpretation of qPCR data is often overlooked, we performed a systematic review to understand normalization strategies entailed in experiments involving senescent cells. We found that, in violation of the Minimum Information for publication of qPCR Experiments (MIQE) guidelines, most reports used only one reference gene to normalize qPCR data, and that stability of the reference genes was either not tested or not reported. To identify new and more stable reference genes in senescent fibroblasts, we analyzed the Shapiro-Wilk normality test and the coefficient of variation per gene using in public RNAseq datasets. We then compared the new reference gene candidates with commonly used ones by using both RNAseq and qPCR data. Finally, we defined the best reference genes to be used universally or in a strain-dependent manner. This study intends to raise awareness of the instability of classical reference genes in senescent cells and to serve as a first attempt to define guidelines for the selection of more reliable normalization methods.

Cellular Senescence: Aging, Cancer, and Injury

Cellular senescence is a permanent state of cell cycle arrest that occurs in proliferating cells subjected to different stresses. Senescence is, therefore, a cellular defense mechanism that prevents the cells to acquire an unnecessary damage. The senescent state is accompanied by a failure to re-enter the cell cycle in response to mitogenic stimuli, an enhanced secretory phenotype and resistance to cell death. Senescence takes place in several tissues during different physiological and pathological processes such as tissue remodeling, injury, cancer, and aging. Although senescence is one of the causative processes of aging and it is responsible of aging-related disorders, senescent cells can also play a positive role. In embryogenesis and tissue remodeling, senescent cells are required for the proper development of the embryo and tissue repair. In cancer, senescence works as a potent barrier to prevent tumorigenesis. Therefore, the identification and characterization of key features of senescence, the induction of senescence in cancer cells, or the elimination of senescent cells by pharmacological interventions in aging tissues is gaining consideration in several fields of research. Here, we describe the known key features of senescence, the cell-autonomous, and noncell-autonomous regulators of senescence, and we attempt to discuss the functional role of this fundamental process in different contexts in light of the development of novel therapeutic targets.

Long term effect of air pollution on incident hospital admissions: Results from the Italian Longitudinal Study within LIFE MED HISS project

BACKGROUND

The LIFE MED HISS project aims at setting up a surveillance system on the long term effects of air pollution on health, using data from National Health Interview Surveys and other currently available sources of information in most European countries. Few studies assessed the long term effect of air pollution on hospital admissions in European cohorts.

OBJECTIVE

The objective of this paper is to estimate the long term effect of fine particulate matter (PM2.5) and nitrogen dioxide (NO₂) on first-ever (incident) cause-specific hospitalizations in Italy.

METHODS

We used data from the Italian Longitudinal Study (ILS), a cohort study based on the 1999-2000 National Health Interview Survey (NHIS), followed up for hospitalization (2001-2008) at individual level. The survey contains information on crucial potential confounders: occupational/educational/marital status, body mass index (BMI), smoking habit and physical activity. Annual mean exposure to PM2.5 and NO₂ was assigned starting from simulated gridded data at spatial resolution of 4 × 4 km² firstly integrated with data from monitoring stations and then up-scaled at municipality level. Statistical analyses were conducted using Cox proportional hazard models with robust variance estimator.

RESULTS

For each cause of hospitalization we estimated the hazard ratios (HRs) adjusted for confounders with 95% Confidence Interval (CI) related to a 10 μg/m³ increase in pollutants. For PM2.5 and NO₂, respectively, we found positive associations for circulatory system diseases [1.05(1.03-1.06); 1.05(1.03-1.07)], myocardial infarction [1.15(1.12-1.18); 1.15(1.12-1.18)], lung cancer [1.18(1.10-1.26); 1.20(1.12-1.28)], kidney cancer [1.24(1.11-1.29); 1.20(1.07-1.33)], all cancers (but lung) [1.06(1.04-1.08); 1.06(1.04-1.08)] and Low Respiratory Tract Infections (LRTI) [1.07 (1.04-1.11); 1.05 (1.02-1.08)].

DISCUSSION

Our results add new evidence on the effects of air pollution on first-ever (incident) hospitalizations, both in urban and rural areas. We demonstrated the feasibility of a low-cost monitoring system based on available data.

Caloric restriction and cellular senescence

Cellular senescence is a state of irreversible growth arrest characterized by hypertrophy and secretion of various bioactive molecules, a phenomenon defined the Senescence-Associated Secretory Phenotype (SASP). Senescent cells are implicated in a number of biological functions, from embryogenesis to aging. Significantly, excessive accumulation of senescent cells is associated to a decline of regenerative capacity and chronic inflammation. In accordance, the removal of senescent cells is sufficient to delay several pathologies and promote healthspan. Calorie restriction (CR) without malnutrition is currently the most effective non-genetic intervention to delay aging phenotypes. Recently, we have shown that CR can prevent accumulation of senescent cells in both mice and humans. Here, we summarize the current knowledge on the molecular and cellular events associated with CR, and define how these events can interfere with the induction of cellular senescence. We discuss the potential side effects of preventing senescence, and the possible alternative dietary interventions with potential senolytic properties.

Abstract 466: Cellular senescence drives skin carcinogenesis

Squamous cell carcinoma (SCC) is the second most common non-melanoma skin cancer, and has a high rate of recurrence and metastasis. Systemic genotoxic chemotherapeutic drugs such as doxorubicin (Doxo) can be used to treat SCC, but these agents can have deleterious long-term side effects, including fueling the development of more aggressive cancers. Some of the adverse effects of genotoxic chemotherapies might be due to their ability to induce cellular senescence. Cellular senescence is a tumor suppressive mechanism that entails a permanent cell growth arrest accompanied by several metabolic changes. Senescent cells increase during aging, and accumulating evidence suggests they can contribute to a variety of age related pathologies, including cancer, by secreting numerous pro-inflammatory molecules, growth factors and proteases, a feature termed the senescence-associated secretory phenotype (SASP). We recently showed that genotoxic and cytotoxic chemotherapeutic agents induce senescence and a SASP in vivo. However, a direct role for senescent cells in skin carcinogenesis in vivo remains unexplored. To investigate the role of senescent cells and the SASP in squamous cell skin carcinogenesis, we first induced senescence with Doxo in p16-3MR transgenic mice. These mice are designed to permit the selective elimination of senescent cells expressing the established senescence marker p16INK4a (p16) by administrating ganciclovir (GCV) which has a high affinity for the herpes simplex viral thymidine kinase (HSV-TK). Phosphorylated GCV is a DNA chain terminator that kills HSV-TK expressing cells by apoptosis. After Doxo treatment, we initiated skin SCC in p16-3MR mice with 7, 12-dimethylbenz[a]anthracene (DMBA), followed by treatment with 12-O-Tetradecanoylphorbol-13-acetate (TPA) to promote skin carcinogenesis. 25 weeks after Doxo treatment, we observed a significant increase in p16 mRNA levels as well as an increase in expression of the SASP factors IL-1α, MMP-9, and IL-17 in the skin of Doxo- compared to PBS- treated mice. Further, the presence of senescent cells resulted in significantly larger and more proliferative tumors compared to PBS-treated mice. Importantly, systemic elimination of Doxo-induced senescent cells using GCV reduced the expression of SASP factors and significantly reduced tumor size, suggesting that senescent cells fuel skin tumor progression. These findings will help our understanding of the role of chemotherapy-induced cellular senescence in skin carcinogenesis and will pave the way for developing novel therapeutics against squamous cell carcinoma and the deleterious side effects of genotoxic chemotherapies.

Citation Format: Fatouma Alimirah, Alexis Valdovinos, Emily Chang, Sena Alptekin, Tanya Pulido, Elijah Jones, Chandani Limbad, Michael Velarde, Marco Demaria, Albert Davalos, Judith Campisi. Cellular senescence drives skin carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 466.

Induction and Validation of Cellular Senescence in Primary Human Cells

Cellular senescence is a state of permanent cell cycle arrest activated in response to different damaging stimuli. Activation of cellular senescence is a hallmark of various pathophysiological conditions including tumor suppression, tissue remodeling and aging. The inducers of cellular senescence in vivo are still poorly characterized. However, a number of stimuli can be used to promote cellular senescence ex vivo. Among them, most common senescence-inducers are replicative exhaustion, ionizing and non-ionizing radiation, genotoxic drugs, oxidative stress, and demethylating and acetylating agents. Here, we will provide detailed instructions on how to use these stimuli to induce fibroblasts into senescence. This protocol can easily be adapted for different types of primary cells and cell lines, including cancer cells. We also describe different methods for the validation of senescence induction. In particular, we focus on measuring the activity of the lysosomal enzyme Senescence-Associated β-galactosidase (SA-β-gal), the rate of DNA synthesis using 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, the levels of expression of the cell cycle inhibitors p16 and p21, and the expression and secretion of members of the Senescence-Associated Secretory Phenotype (SASP). Finally, we provide example results and discuss further applications of these protocols.

The effects of graded caloric restriction: XII. Comparison of mouse to human impact on cellular senescence in the colon

Calorie restriction (CR) is an effective strategy to delay the onset and progression of aging phenotypes in a variety of organisms. Several molecular players are involved in the anti‐aging effects of CR, but mechanisms of regulation are poorly understood. Cellular senescence—a cellular state of irreversible growth arrest—is considered a basic mechanism of aging. Senescent cells accumulate with age and promote a number of age‐related pathologies. Whether environmental conditions such as diet affect the accumulation of cellular senescence with age is still unclear. Here, we show that a number of classical transcriptomic markers of senescent cells are reduced in adult but relatively young mice under CR. Moreover, we demonstrate that such senescence markers are not induced in the colon of middle‐age human volunteers under CR in comparison with age‐matched volunteers consuming normal Western diets. Our data support the idea that the improvement in health span observed in different organisms under CR might be partly due to a reduction in the number of senescent cells.

Hallmarks of Cellular Senescence

Cellular senescence is a permanent state of cell cycle arrest that promotes tissue remodeling during development and after injury, but can also contribute to the decline of the regenerative potential and function of tissues, to inflammation, and to tumorigenesis in aged organisms. Therefore, the identification, characterization, and pharmacological elimination of senescent cells have gained attention in the field of aging research. However, the nonspecificity of current senescence markers and the existence of different senescence programs strongly limit these tasks. Here, we describe the molecular regulators of senescence phenotypes and how they are used for identifying senescent cells in vitro and in vivo. We also highlight the importance that these levels of regulations have in the development of therapeutic targets.

Cellular Senescence Is Induced by the Environmental Neurotoxin Paraquat and Contributes to Neuropathology Linked to Parkinson's Disease

Exposure to the herbicide paraquat (PQ) is associated with an increased risk of idiopathic Parkinson's disease (PD). Therapies based on PQ's presumed mechanisms of action have not, however, yielded effective disease therapies. Cellular senescence is an anticancer mechanism that arrests proliferation of replication-competent cells and results in a pro-inflammatory senescence-associated secretory phenotype (SASP) capable of damaging neighboring tissues. Here, we demonstrate that senescent cell markers are preferentially present within astrocytes in PD brain tissues. Additionally, PQ was found to induce astrocytic senescence and an SASP in vitro and in vivo, and senescent cell depletion in the latter protects against PQ-induced neuropathology. Our data suggest that exposure to certain environmental toxins promotes accumulation of senescent cells in the aging brain, which can contribute to dopaminergic neurodegeneration. Therapies that target senescent cells may constitute a strategy for treatment of sporadic PD, for which environmental exposure is a major risk factor.

Unmasking Transcriptional Heterogeneity in Senescent Cells

Cellular senescence is a state of irreversibly arrested proliferation, often induced by genotoxic stress [1]. Senescent cells participate in a variety of physiological and pathological conditions, including tumor suppression [2], embryonic development [3, 4], tissue repair [5-8], and organismal aging [9]. The senescence program is variably characterized by several non-exclusive markers, including constitutive DNA damage response (DDR) signaling, senescence-associated β-galactosidase (SA-βgal) activity, increased expression of the cyclin-dependent kinase (CDK) inhibitors p16INK4A (CDKN2A) and p21CIP1 (CDKN1A), increased secretion of many bio-active factors (the senescence-associated secretory phenotype, or SASP), and reduced expression of the nuclear lamina protein LaminB1 (LMNB1) [1]. Many senescence-associated markers result from altered transcription, but the senescent phenotype is variable, and methods for clearly identifying senescent cells are lacking [10]. Here, we characterize the heterogeneity of the senescence program using numerous whole-transcriptome datasets generated by us or publicly available. We identify transcriptome signatures associated with specific senescence-inducing stresses or senescent cell types and identify and validate genes that are commonly differentially regulated. We also show that the senescent phenotype is dynamic, changing at varying intervals after senescence induction. Identifying novel transcriptome signatures to detect any type of senescent cell or to discriminate among diverse senescence programs is an attractive strategy for determining the diverse biological roles of senescent cells and developing specific drug targets.

Local clearance of senescent cells attenuates the development of post-traumatic osteoarthritis and creates a pro-regenerative environment

Senescent cells (SnCs) accumulate in many vertebrate tissues with age and contribute to age-related pathologies, presumably through their secretion of factors contributing to the senescence-associated secretory phenotype (SASP). Removal of SnCs delays several pathologies and increases healthy lifespan. Aging and trauma are risk factors for the development of osteoarthritis (OA), a chronic disease characterized by degeneration of articular cartilage leading to pain and physical disability. Senescent chondrocytes are found in cartilage tissue isolated from patients undergoing joint replacement surgery, yet their role in disease pathogenesis is unknown. To test the idea that SnCs might play a causative role in OA, we used the p16-3MR transgenic mouse, which harbors a p16^INK4a (Cdkn2a) promoter driving the expression of a fusion protein containing synthetic Renilla luciferase and monomeric red fluorescent protein domains, as well as a truncated form of herpes simplex virus 1 thymidine kinase (HSV-TK). This mouse strain allowed us to selectively follow and remove SnCs after anterior cruciate ligament transection (ACLT). We found that SnCs accumulated in the articular cartilage and synovium after ACLT, and selective elimination of these cells attenuated the development of post-traumatic OA, reduced pain and increased cartilage development. Intra-articular injection of a senolytic molecule that selectively killed SnCs validated these results in transgenic, non-transgenic and aged mice. Selective removal of the SnCs from in vitro cultures of chondrocytes isolated from patients with OA undergoing total knee replacement decreased expression of senescent and inflammatory markers while also increasing expression of cartilage tissue extracellular matrix proteins. Collectively, these findings support the use of SnCs as a therapeutic target for treating degenerative joint disease.

Senescent cells: New target for an old treatment?

Many genotoxic chemotherapies have debilitating side effects and induce cellular senescence in normal tissues. Senescent cells acquire a pro-inflammatory phenotype which contributes to local and systemic inflammation. Eliminating senescent cells reduce several short- and long-term effects of the drugs, providing a new target to reduce the toxicity of anticancer treatments.

Therapeutic interventions for aging: the case of cellular senescence

Organismal aging is a multifactorial process characterized by the onset of degenerative conditions and cancer. One of the key drivers of aging is cellular senescence, a state of irreversible growth arrest induced by many pro-tumorigenic stresses. Senescent cells accumulate late in life and at sites of age-related pathologies, where they contribute to disease onset and progression through complex cell and non-cell autonomous effects. Here, we summarize the mechanisms by which cellular senescence can promote aging, and we offer an extensive description of current potential pharmacological interventions for senescent cells, highlighting limitations and suggesting alternatives.

Cellular Senescence Promotes Adverse Effects of Chemotherapy and Cancer Relapse

Cellular senescence suppresses cancer by irreversibly arresting cell proliferation. Senescent cells acquire a proinflammatory senescence-associated secretory phenotype. Many genotoxic chemotherapies target proliferating cells nonspecifically, often with adverse reactions. In accord with prior work, we show that several chemotherapeutic drugs induce senescence of primary murine and human cells. Using a transgenic mouse that permits tracking and eliminating senescent cells, we show that therapy-induced senescent (TIS) cells persist and contribute to local and systemic inflammation. Eliminating TIS cells reduced several short- and long-term effects of the drugs, including bone marrow suppression, cardiac dysfunction, cancer recurrence, and physical activity and strength. Consistent with our findings in mice, the risk of chemotherapy-induced fatigue was significantly greater in humans with increased expression of a senescence marker in T cells prior to chemotherapy. These findings suggest that senescent cells can cause certain chemotherapy side effects, providing a new target to reduce the toxicity of anticancer treatments.

SIGNIFICANCE

Many genotoxic chemotherapies have debilitating side effects and also induce cellular senescence in normal tissues. The senescent cells remain chronically present where they can promote local and systemic inflammation that causes or exacerbates many side effects of the chemotherapy. Cancer Discov; 7(2); 165-76. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 115.

p53 and rapamycin are additive

Mechanistic target of rapamycin (mTOR) is a kinase found in a complex (mTORC1) that enables macromolecular synthesis and cell growth and is implicated in cancer etiology. The rapamycin-FK506 binding protein 12 (FKBP12) complex allosterically inhibits mTORC1. In response to stress, p53 inhibits mTORC1 through a separate pathway involving cell signaling and amino acid sensing. Thus, these different mechanisms could be additive. Here we show that p53 improved the ability of rapamycin to: 1) extend mouse life span, 2) suppress ionizing radiation (IR)-induced senescence-associated secretory phenotype (SASP) and 3) increase the levels of amino acids and citric acid in mouse embryonic stem (ES) cells. This additive effect could have implications for cancer treatment since rapamycin and p53 are anti-oncogenic.

Targeting Senescent Cells: Possible Implications for Delaying Skin Aging: A Mini-Review

Senescent cells are induced by a wide variety of stimuli. They accumulate in several tissues during aging, including the skin. Senescent cells secrete proinflammatory cytokines, chemokines, growth factors, and proteases, a phenomenon called senescence-associated secretory phenotype (SASP), which are thought to contribute to the functional decline of the skin as a consequence of aging. Due to the potential negative effects of the SASP in aged organisms, drugs that selectively target senescent cells represent an intriguing therapeutic strategy to delay aging and age-related diseases. Here, we review studies on the role of senescent cells in the skin, with particular emphasis on the age-related mechanisms and phenotypes associated with excessive accumulation of cellular senescence. We discuss the aberrant behavior of senescent cells in aging and how the different signaling pathways associated with survival and secretion of senescent cells can be engaged for the development of targeted therapies.

Cellular senescence and tumor promotion: Is aging the key?

The senescence response is a potent tumor suppressor mechanism characterized by an irreversible growth arrest in response to potentially oncogenic signals to prevent the proliferation of damaged cells. Late in life, some of the features of senescent cells seem to mediate the development of age-related pathologies, including cancer. In the present review, we present a summary of the current knowledge regarding the causes, effector pathways and cellular features of senescence. We also discuss how the senescence response, initially a tumor suppressor mechanism, turns into a tumor promoter apparently as a consequence of aging. We argue that three age-related phenomena--senescence-associated secretory phenotype (SASP) dysregulation, decline in the immune system function and genomic instability--could contribute, independently or synergistically, to deteriorate the efficacy of the senescence response in stopping cancer. As a consequence, senescent cells could be considered premalignant cells, and targeting senescent cells could be a preventive and therapeutic strategy against cancer.

Simvastatin suppresses breast cancer cell proliferation induced by senescent cells

Cellular senescence suppresses cancer by preventing the proliferation of damaged cells, but senescent cells can also promote cancer though the pro-inflammatory senescence-associated secretory phenotype (SASP). Simvastatin, an HMG-coA reductase inhibitor, is known to attenuate inflammation and prevent certain cancers. Here, we show that simvastatin decreases the SASP of senescent human fibroblasts by inhibiting protein prenylation, without affecting the senescent growth arrest. The Rho family GTPases Rac1 and Cdc42 were activated in senescent cells, and simvastatin reduced both activities. Further, geranylgeranyl transferase, Rac1 or Cdc42 depletion reduced IL-6 secretion by senescent cells. We also show that simvastatin mitigates the effects of senescent conditioned media on breast cancer cell proliferation and endocrine resistance. Our findings identify a novel activity of simvastatin and mechanism of SASP regulation. They also suggest that senescent cells, which accumulate after radio/chemo therapy, promote endocrine resistance in breast cancer and that simvastatin might suppress this resistance.

The DNA damage response induces inflammation and senescence by inhibiting autophagy of GATA4

Cellular senescence is a terminal stress-activated program controlled by the p53 and p16(INK4a) tumor suppressor proteins. A striking feature of senescence is the senescence-associated secretory phenotype (SASP), a pro-inflammatory response linked to tumor promotion and aging. We have identified the transcription factor GATA4 as a senescence and SASP regulator. GATA4 is stabilized in cells undergoing senescence and is required for the SASP. Normally, GATA4 is degraded by p62-mediated selective autophagy, but this regulation is suppressed during senescence, thereby stabilizing GATA4. GATA4 in turn activates the transcription factor NF-κB to initiate the SASP and facilitate senescence. GATA4 activation depends on the DNA damage response regulators ATM and ATR, but not on p53 or p16(INK4a). GATA4 accumulates in multiple tissues, including the aging brain, and could contribute to aging and its associated inflammation.

Of flies, mice, and men: evolutionarily conserved tissue damage responses and aging

Studies in flies, mice, and human models have provided a conceptual framework for how paracrine interactions between damaged cells and the surrounding tissue control tissue repair. These studies have amassed evidence for an evolutionarily conserved secretory program that regulates tissue homeostasis. This program coordinates cell survival and proliferation during tissue regeneration and repair in young animals. By virtue of chronic engagement, however, it also contributes to the age-related decline of tissue homeostasis leading to degeneration, metabolic dysfunction, and cancer. Here, we review recent studies that shed light on the nature and regulation of this evolutionarily conserved secretory program.

An essential role for senescent cells in optimal wound healing through secretion of PDGF-AA

Cellular senescence suppresses cancer by halting the growth of premalignant cells, yet the accumulation of senescent cells is thought to drive age-related pathology through a senescence-associated secretory phenotype (SASP), the function of which is unclear. To understand the physiological role(s) of the complex senescent phenotype, we generated a mouse model in which senescent cells can be visualized and eliminated in living animals. We show that senescent fibroblasts and endothelial cells appear very early in response to a cutaneous wound, where they accelerate wound closure by inducing myofibroblast differentiation through the secretion of platelet-derived growth factor AA (PDGF-AA). In two mouse models, topical treatment of senescence-free wounds with recombinant PDGF-AA rescued the delayed wound closure and lack of myofibroblast differentiation. These findings define a beneficial role for the SASP in tissue repair and help to explain why the SASP evolved.

From tissue invasion to glucose metabolism: the many aspects of signal transducer and activator of transcription 3 pro-oncogenic activities

Abstract Background: The pro-oncogenic transcription factor STAT3 is constitutively active in tumours of many different origins, which often become addicted to its activity. STAT3 is believed to contribute to the initial survival of pre-cancerous cells as well as to hyper-proliferation and, later, metastasis.

MATERIALS AND METHODS

To evaluate the contribution of enhanced STAT3 activation in a controlled model system, we generated knock-in mice in which a mutant constitutively active Stat3C allele replaces the endogenous wild-type allele and analysed its contribution to breast tumorigenesis. Moreover, we generated Stat3C/C MEF cells and analysed their gene expression and metabolic profiles.

RESULTS

Constitutively active STAT3 could enhance the tumorigenic power of the rat Neu oncogene in MMTV-Neu transgenic mice and trigger the production of earlier onset and more invasive mammary tumours. Tumour-derived cell lines displayed higher migrating, invading and metastatic ability and showed disrupted distribution of cell-cell junction markers. These features were mediated by STAT3-dependent over-expression of the C-terminal tensin-like (Cten) focal adhesion protein. Moreover, STAT3C alone was able to induce aerobic glycolysis and down-regulate mitochondrial activity, both in primary fibroblasts and in STAT3-dependent tumour cell lines, acting via both HIF-1α-dependent and independent mechanisms.

CONCLUSIONS

STAT3 can induce a metabolic switch that predisposes cells to aberrant survival, enhanced proliferation and, finally, tumour transformation. Later, enhanced Cten expression contributes to tissue infiltration and metastasis. While not excluding the contribution of many other tumour-specific STAT3 target genes, our data provide a unifying explanation of several pro-oncogenic STAT3 activities.

Cellular senescence and the aging brain

Cellular senescence is a potent anti-cancer mechanism that arrests the proliferation of mitotically competent cells to prevent malignant transformation. Senescent cells accumulate with age in a variety of human and mouse tissues where they express a complex 'senescence-associated secretory phenotype' (SASP). The SASP includes many pro-inflammatory cytokines, chemokines, growth factors and proteases that have the potential to cause or exacerbate age-related pathology, both degenerative and hyperplastic. While cellular senescence in peripheral tissues has recently been linked to a number of age-related pathologies, its involvement in brain aging is just beginning to be explored. Recent data generated by several laboratories suggest that both aging and age-related neurodegenerative diseases are accompanied by an increase in SASP-expressing senescent cells of non-neuronal origin in the brain. Moreover, this increase correlates with neurodegeneration. Senescent cells in the brain could therefore constitute novel therapeutic targets for treating age-related neuropathologies.

PKM2, STAT3 and HIF-1α: The Warburg's vicious circle

The M2 isoform of pyruvate kinase, highly expressed in tumor cells, is known to engage a feed forward loop with the glycolysis master transcription factor HIF-1α. Gao and co-authors recently showed that dimeric PKM2 localizes to the nucleus in highly proliferating cancer cells, where it regulates in vivo growth by acting as a protein kinase and directly activating STAT3. STAT3 is therefore a novel player of the PKM2/HIF-1α feedback loop, since HIF-induced PKM2 activates STAT3 that in turn induces HIF-1α expression. These findings have profound implications for understanding the complex connections between gene regulation, metabolism, survival and proliferation in cancer.

Environmental stress, ageing and glial cell senescence: a novel mechanistic link to Parkinson's disease?

Exposure to environmental toxins is associated with a variety of age-related diseases including cancer and neurodegeneration. For example, in Parkinson's disease (PD), chronic environmental exposure to certain toxins has been linked to the age-related development of neuropathology. Neuronal damage is believed to involve the induction of neuroinflammatory events as a consequence of glial cell activation. Cellular senescence is a potent anti-cancer mechanism that occurs in a number of proliferative cell types and causes the arrest of proliferation of cells at risk of malignant transformation following exposure to potentially oncogenic stimuli. With age, senescent cells accumulate and express a senescence-associated secretory phenotype (SASP; that is the robust secretion of many inflammatory cytokines, growth factors and proteases). Whereas cell senescence in peripheral tissues has been causally linked to a number of age-related pathologies, little is known about the induction of cellular senescence and the SASP in the brain. On the basis of recently reported findings, we propose that environmental stressors associated with PD may act in part by eliciting senescence and the SASP within non neuronal glial cells in the ageing brain, thus contributing to the characteristic decline in neuronal integrity that occurs in this disorder.

Senescent cells and their secretory phenotype as targets for cancer therapy

Cancer is a devastating disease that increases exponentially with age. Cancer arises from cells that proliferate in an unregulated manner, an attribute that is countered by cellular senescence. Cellular senescence is a potent tumor-suppressive process that halts the proliferation, essentially irreversibly, of cells at risk for malignant transformation. A number of anti-cancer drugs have emerged that induce tumor cells to undergo cellular senescence. However, although a senescence response can halt the proliferation of cancer cells, the presence of senescent cells in tissues has been associated with age-related diseases, including, ironically, late-life cancer. Thus, anti-cancer therapies that can induce senescence might also drive aging phenotypes and age-related pathology. The deleterious effects of senescent cells most likely derive from their senescence-associated secretory phenotype or SASP. The SASP entails the secretion of numerous inflammatory cytokines, growth factors and proteases that can render the tissue microenvironment favorable for tumor growth. Here, we discuss the beneficial and detrimental effects of inducing cellular senescence, and propose strategies for targeting senescent cells as a means to fight cancer.

Glucocorticoids suppress selected components of the senescence-associated secretory phenotype

Cellular senescence suppresses cancer by arresting the proliferation of cells at risk for malignant transformation. Recently, senescent cells were shown to secrete numerous cytokines, growth factors, and proteases that can alter the tissue microenvironment and may promote age-related pathology. To identify small molecules that suppress the senescence-associated secretory phenotype (SASP), we developed a screening protocol using normal human fibroblasts and a library of compounds that are approved for human use. Among the promising library constituents was the glucocorticoid corticosterone. Both corticosterone and the related glucocorticoid cortisol decreased the production and secretion of selected SASP components, including several pro-inflammatory cytokines. Importantly, the glucocorticoids suppressed the SASP without reverting the tumor suppressive growth arrest and were efficacious whether cells were induced to senesce by ionizing radiation or strong mitogenic signals delivered by oncogenic RAS or MAP kinase kinase 6 overexpression. Suppression of the prototypical SASP component IL-6 required the glucocorticoid receptor, which, in the presence of ligand, inhibited IL-1α signaling and NF-κB transactivation activity. Accordingly, co-treatments combining glucocorticoids with the glucocorticoid antagonist RU-486 or recombinant IL-1α efficiently reestablished NF-κB transcriptional activity and IL-6 secretion. Our findings demonstrate feasibility of screening for compounds that inhibit the effects of senescent cells. They further show that glucocorticoids inhibit selected components of the SASP and suggest that corticosterone and cortisol, two FDA-approved drugs, might exert their effects in part by suppressing senescence-associated inflammation.

Direct costs in diabetic and non diabetic people: the population-based Turin study, Italy

BACKGROUND AND AIMS

We compared direct costs of diabetic and non diabetic people covered by the Italian National Health System, focusing on the influence of age, sex, type of diabetes and treatment.

METHODS AND RESULTS

Diabetic people living in Turin were identified through the Regional Diabetes Registry and the files of hospital discharges and prescriptions. Data sources were linked to the administrative databases to assess health care services used by diabetic (n = 33,792) and non diabetic people(n = 863,123). Data were analyzed with the two-part model; the estimated direct costs per person/year were €3660.8 in diabetic people and €895.6 in non diabetic people, giving a cost ratio of 4.1. Diabetes accounted for 11.4% of total health care expenditure. The costs were attributed to hospitalizations (57.2%), drugs (25.6%), to outpatient care (11.9%), consumable goods (4.4%) and emergency care (0.9%). Estimated costs increased from € 2670.8 in diabetic people aged <45 years to € 3724.1 in those aged >74 years, the latter representing two third of the diabetic cohort; corresponding figures in non diabetic people were € 371.6 and € 2155.9. In all expenditure categories cost ratios of diabetic vs non diabetic people were higher in people aged <45 years, in type 1 diabetes and in insulin-treated type 2 diabetes.

CONCLUSION

Direct costs are 4-fold higher in diabetic than in non diabetic people, mainly due to care of the elderly and inpatient care. In developed countries, demographic changes will have a profound impact on costs for diabetes in next years.

Lamin B1 loss is a senescence-associated biomarker

Cellular senescence is a potent tumor-suppressive mechanism that arrests cell proliferation and has been linked to aging. However, studies of senescence have been impeded by the lack of simple, exclusive biomarkers of the senescent state. Senescent cells develop characteristic morphological changes, which include enlarged and often irregular nuclei and chromatin reorganization. Because alterations to the nuclear lamina can affect both nuclear morphology and gene expression, we examined the nuclear lamina of senescent cells. We show here than lamin B1 is lost from primary human and murine cell strains when they are induced to senesce by DNA damage, replicative exhaustion, or oncogene expression. Lamin B1 loss did not depend on the p38 mitogen-activated protein kinase, nuclear factor-κB, ataxia telangiectasia-mutated kinase, or reactive oxygen species signaling pathways, which are positive regulators of senescent phenotypes. However, activation of either the p53 or pRB tumor suppressor pathway was sufficient to induce lamin B1 loss. Lamin B1 declined at the mRNA level via a decrease in mRNA stability rather than by the caspase-mediated degradation seen during apoptosis. Last, lamin B1 protein and mRNA declined in mouse tissue after senescence was induced by irradiation. Our findings suggest that lamin B1 loss can serve as biomarker of senescence both in culture and in vivo.

STAT3 can serve as a hit in the process of malignant transformation of primary cells

The transcription factor signal transducer and activator of transcription 3 (STAT3) acts downstream of many pro-oncogenic signals, including cytokines, growth factors and oncogenes, and is accordingly constitutively active in a wide variety of tumors that often become addicted to it. Moreover, STAT3 is a key player in mediating inflammation-driven tumorigenesis, where its aberrant continuous activation is typically triggered by local or systemic production of the pro-inflammatory cytokine IL-6. We recently showed that mouse embryonic fibroblasts (MEFs) derived from STAT3C k/in mice, which express physiological levels of the constitutively active mutant STAT3C, display features of transformed cells such as increased proliferation, resistance to apoptosis and senescence, and aerobic glycolysis. Here, we show that pre-existing constitutively active STAT3 is sufficient to prime primary MEFs for malignant transformation upon spontaneous immortalization. Transformation is strictly STAT3-dependent and correlates with high resistance to apoptosis and enhanced expression of anti-apoptotic/pro-survival genes. Additionally, hypoxia inducible factor (HIF)-1α level is elevated by twofold and contributes to STAT3 oncogenic activity by supporting high rates of aerobic glycolysis. Thus, constitutively active STAT3, an accepted essential factor for tumor growth/progression, can also act as a first hit in multistep carcinogenesis; this ability to predispose cells to malignant transformation may be particularly relevant in the pro-oncogenic niche represented by chronically inflamed tissues.

[The use of municipality-level data on mortality in Italy: SENTIERI Project]

In Italy, complete municipality-level data on specific-cause mortality have been available at central level since 1980; Italy's National Institute of Statistics (Istat) collects data from all municipalities using two sources: i) the Office of Vital Statistics; and ii) the Civil Status Office. The Office of Vital Statistics records data on events such as births, deaths and migration for the population with official residence in the municipality, with the aim of describing the resident population's structure and composition. The Civil Status Office records data on the demographic dynamics (not only marital status but also causes of death); the data refer to the population living in the municipality, independently of official residence. Changes in the status of a municipality (e.g., the creation of a new municipality or the unification of diverse municipalities) are often not recorded simultaneously by these two offices, so that the data do not correspond.

A STAT3-mediated metabolic switch is involved in tumour transformation and STAT3 addiction

The pro-oncogenic transcription factor STAT3 is constitutively activated in a wide variety of tumours that often become addicted to its activity, but no unifying view of a core function determining this widespread STAT3-dependence has yet emerged. We show here that constitutively active STAT3 acts as a master regulator of cell metabolism, inducing aerobic glycolysis and down-regulating mitochondrial activity both in primary fibroblasts and in STAT3-dependent tumour cell lines. As a result, cells are protected from apoptosis and senescence while becoming highly sensitive to glucose deprivation. We show that enhanced glycolysis is dependent on HIF-1α up-regulation, while reduced mitochondrial activity is HIF-1α-independent and likely caused by STAT3-mediated down-regulation of mitochondrial proteins. The induction of aerobic glycolysis is an important component of STAT3 pro-oncogenic activities, since inhibition of STAT3 tyrosine phosphorylation in the tumour cell lines down-regulates glycolysis prior to leading to growth arrest and cell death, both in vitro and in vivo. We propose that this novel, central metabolic role is at the core of the addiction for STAT3 shown by so many biologically different tumours.

Factors affecting in-hospital heat-related mortality: a multi-city case-crossover analysis

BACKGROUND

Several studies have identified strong effects of high temperatures on mortality at population level; however, individual vulnerability factors associated with heat-related in-hospital mortality are largely unknown. The objective of the study was to evaluate heat-related in-hospital mortality using a multi-city case-crossover analysis.

METHODS

We studied residents of four Italian cities, aged 65+ years, who died during 1997-2004. For 94,944 individuals who died in hospital and were hospitalised two or more days before death, demographics, chronic conditions, primary diagnoses of last event and hospital wards were considered. A city-specific case-crossover analysis was performed to evaluate the association between apparent temperature and mortality. Pooled odds ratios (OR) of dying on a day with a temperature of 30 degrees C compared to a day with a temperature of 20 degrees C were estimated with a random-effects meta-analysis.

RESULTS

We estimated an overall OR of 1.32 (95% confidence interval: 1.25, 1.39). Age, marital status and hospital ward were important risk indicators. Patients in general medicine were at higher risk than those in high and intensive care units. A history of psychiatric disorders and cerebrovascular diseases gave a higher vulnerability. Mortality was greater among patients hospitalised for heart failure, stroke and chronic pulmonary diseases.

CONCLUSIONS

In-hospital mortality is strongly associated with high temperatures. A comfortable temperature in hospitals and increased attention to vulnerable patients during heatwaves, especially in general medicine, are necessary preventive measures.

Airport and city-centre temperatures in the evaluation of the association between heat and mortality

A variety of ambient exposure indicators have been used to evaluate the impact of high temperature on mortality and in the identification of susceptible population sub-groups, but no study has evaluated how airport and city centre temperatures differ in their association with mortality during summer. This study considers the differences in temperatures measured at the airport and in the city centre of three Italian cities (Milan, Rome and Turin) and investigates the impact of these measures on daily mortality. The case-crossover design was applied to evaluate the association between daily mean apparent temperature (MAT) and daily total mortality. The analysis was conducted for the entire population and for subgroups defined by demographic characteristics, socioeconomic status and chronic comorbidity (based on hospitalisation during the preceding 2 years). The percentage risk of dying, with 95% confidence intervals (95% CI), on a day with MAT at the 95th percentile with respect to the 25th percentile of the June-September daily distribution was estimated. Airport and city-centre temperature distributions, which vary among cities and between stations, have a heterogeneous impact on mortality. Milan was the city with the greatest differences in mean MAT between airport and city stations, and the overall risk of dying was greater when airport MAT (+47% increase, 95%CI 38-57) was considered in comparison to city MAT (+37% increase, 95%CI 30-45). In Rome and Turin, the results were very similar for both apparent temperature measures. In all cities, the elderly, women and subjects with previous psychiatric conditions, depression, heart and circulation disorders and cerebrovascular disease were at higher risk of dying during hot days, and the degree of effect modification was similar using airport or city-centre MAT. Studies on the impact of meteorological variables on mortality, or other health indicators, need to account for the possible differences between airport and city centre meteorological variables in order to give more accurate estimates of health effects.

[Carpal tunnel syndrome (CTS) in the Piedmont Region: regional incidence and prevalence of CTS based on hospital records of patients who underwent surgery]

BACKGROUND

Carpal tunnel syndrome (CTS) is the most frequent entrapment neuropathy of the upper extremities. Despite CTS being a priority for public health, only a few studies have investigated the prevalence and incidence in the general population. In Italy, administrative data are available only for CTS cases which were judged work-related by the Workers Compensation Board. These data indicate a steady increase in CTS over the last decade. Hospital admission archives (SDO) also contain information on CTS patients who underwent surgery.

OBJECTIVES

To determine: 1) the incidence and prevalence of first CTS, based on hospital records of patients who underwent surgery in the Piedmont Region; 2) to describe the geographical and temporal variation.

METHODS

Crude and standardized incidence rates of CTS were computed for the period 2002-2003; geographical variation was assessed using bayesan estimators to detect spatial clusters. Crude and standardized prevalence rates of first hospitalization were calculated for every two-year period between 1996 and 2003.

RESULTS AND CONCLUSIONS

The crude incidence rate was 227.2 (C.I.95% 221.9-232.7) per 100,000 women and 54.4 (C.I. 95% 51.9-57.1) per 100,000 men. The prevalence of first hospitalization was very high and varied widely by geographic area. Two possible explanations for such wide variation between areas include differences in exposure to risk factors for CTS and in the diagnostic criteria used. The increasing prevalence over time was only partly explained by an increase in work-related cases. The development of standardized diagnostic criteria would improve understanding of the effect of workplace exposures on CTS. The number of new cases per year in Piedmont was estimated at 1,500, much higher than the compensation claims related to CTS. Health education campaigns addressed to general practitioners on compensation law could improve reporting to the workers' compensation board.

[Workplace injuries and professional mobility correlated with health problems. The potential and limitations of the ISTAT Labour Force survey--July 1999]

BACKGROUND

Knowledge on the occupational and social factors that influence the relationship between illness, absence from work and occupational mobility is at present insufficient.

OBJECTIVES

To map out, by social class and occupational group, the impact of health problems on work and the distribution of accidents and morbidity associated with occupation.

METHODS

Using data from the National Survey of the Italian Labour Force (ISTAT, 1999), covering a sample of 200,384 subjects, prevalence odds ratios of morbidity, work injuries and change of occupation due to health problems were calculated by social class and occupation, adjusting for age and residence.

RESULTS

The working class showed a higher risk, due to health problems, of a reduction in time worked (OR = 3.70 in men and OR = 4.10 in women), of choosing to work part-time (OR = 2.04 in men and OR = 2.27 in women), or of withdrawing from the workforce (for artisans, skilled manual workers, farmers and agricultural labourers OR = 1.63 in men and OR = 1.47 in women). This class was also at a greater disadvantage not only with respect to accident rates (OR = 1.85 in men and OR = 1.88 in women), but also with respect to the time needed for post-trauma rehabilitation and return to work (for absences of one week to one month: OR = 1.67 and 1.83 for men and women, respectively; for absences of more than one month: OR = 1.29 and OR = 1.69). Moreover, the working class, when compared to other social classes, had a higher rate of suffering from illness, physical impairment or other physical and psychological problems caused or aggravated by working activity (25% in men and 32% in women).

CONCLUSIONS

The ISTAT National Survey provides an estimate of minor accidents with prognoses of less than three days, including those not reported to the National Institute for Insurance against Occupational Accidents and Diseases (INAIL). This allows a preliminary exploration of the relationship between health problems and occupational mobility; however, it seems necessary to collect more detailed information in order to more exhaustively explore the mechanisms which generate the inequalities observed.

[Healthy life expectancy in the occupied segment of the Turin population]

BACKGROUND

The indicators of healthy life expectancy measure differences in health among various population subgroups more sensitively than do indicators of mortality.

OBJECTIVES

The aim of the study was to analyze some of the above indicators to evaluate the differences among occupational categories in Turin.

METHODS

Mortality tables by occupation were calculated on Turin residents, aged 18-64 years in 1991, using the Turin Longitudinal Study which combines personal, census, and health information for the residents of the city. Longitudinal assessments of health expectancy were obtained by means of record-linkage with the Cancer Registry, the Diabetes Registry, and hospital discharge records. In addition, prevalence estimates of good health, disability, and chronic illness, obtained from ISTAT (Central Statistics Institute) investigations in 1999-2000 were combined with mortality data using Sullivan's algorithm.

RESULTS

Among men there was a systematic disadvantage in almost all indicators of health expectancy for some manual occupations, while jobs requiring more qualifications were more advantaged. The health profile for women was more controversial, with an overall disadvantage among women who were professional consultants, although this group showed substantial variability: the legal professions had the lowest life and health expectancies, with approximately 3 years of life less than the health professions, which were among the most advantaged.

DISCUSSION

The various indicators gave results which were at times conflicting, especially because the information obtained from the available sources had major limitations. The development of indicators needs to aim for greater homogeneity between mortality and health data to ensure maximum comparability.

[Differences of perceived health and lifestyle by occupational groups in the Italian ISTAT (Central Statistic Institute) health survey]

BACKGROUND

Little is known about the distribution by occupation of chronic illness, disability, morbidity, and lifestyles which put health at risk.

OBJECTIVES

To provide a map of the social inequalities in various dimensions of health and lifestyle by social class and for specific occupational groups. To formulate a hypothesis about the mechanisms which generate these inequalities.

METHODS

Prevalence rate ratios and prevalence odds ratios of perceived health, chronic illness, disability, absenteeism, trauma, smoking, and obesity calculated with data from the 1999-2000 Italian ISTAT (Central Statistics Institute) health survey; the study population includes adults (aged over 18 years) employed, or searching for a job, or withdrawn from the workforce.

RESULTS

Among workers in manual unskilled labour, construction and agriculture are noted for worse health and more unhealthy lifestyles than average. For example, perceived bad health is more widespread among agricultural labourers (OR = 1.63), masons and construction machine operators (OR = 1.75), transport drivers (OR = 1.40), male caretakers, custodians, janitors and domestic help (OR = 1.46), electro-technicians (OR = 1.44), leatherworkers and shoemakers (OR = 3.58), miners and quarrymen (OR = 2.60), earthenware and stone workers (OR = 2.14), garment and furnishings workers (OR = 1.86); in female workers excess risk for perceived bad health was present among agricultural labourers (OR = 2.08), caretakers, custodians, janitors and domestic helpers (OR = 1.49), waitresses, cooks and bartenders, (OR = 1.44), and textile workers (OR = 1.67). Smoking was more widespread among chemical workers (OR = 1.41), and in miners and quarrymen (OR = 1.30). An excess risk of smoking of 20-25% was evident in spinners, weavers and finishers; masons, (and) builders; waiters, cooks and bartenders; garment and furnishings workers; porters and warehouse workers. The risk was 10% higher among foundry workers and forgers, plumbers, carpenters and welders, and transport drivers. Among women the propensity to smoke was higher among waitresses, cooks and bartenders (OR = 1.37), cleaners, commerce and service workers (OR = 1.22). Other occupational groups with an increased smoking prevalence, where women were less represented, included: chemical workers (OR = 2.25), butchers (OR = 1.97), postwomen (OR = 1.58), plastics workers (OR = 1.56), shippers (OR = 1.37).

CONCLUSIONS

It can be hypothesized on the one hand that there are factors and mechanisms common to the various occupational groups belonging to the same social class; on the other, there are factors and mechanisms specific to certain occupational categories. The latter can generate specific health subcultures. A greater integration between qualitative and quantitative research is recommended, which would yield better explanations of the observed inequalities.

[Occupational mortality in Italy during 1992, assessed through record-linkage between pension records and death certificates]

BACKGROUND

The creation of a surveillance system of occupational mortality in Italy is limited by the low quality of information on occupation in death certificates, since the information is often incomplete or lacking and because only the occupation at the time of death is registered.

OBJECTIVE

To evaluate the possible use of INPS (National Institute of Social Security) records for the purpose of surveillance of occupational mortality, in terms of feasibility of setting up a system and of validity of the results obtained.

METHODS

Death records of 218,510 subjects aged 18-74, deceased in the 12 months following the 1991 census, were obtained from ISTAT (Central Statistics Institute). These were combined through record-linkage with the INPS social security archives, which contain the employment records by economic sector going back to 1974, in order to assign these deaths the sector in which they had worked the longest. Mortality by specific causes was evaluated by industry by means of a proportional mortality analysis stratified by sex and occupational status, and adjusted for age, education, marital status, geographical area of birth, drawing a disability pension, employment status at the time of death and work instability.

RESULTS

Record-linkage allowed attribution of the longest held job to 70% of the deaths recorded. Results are presented and discussed only on mortality in men due to asbestosis and silicosis, and causes of death with a substantial proportion attributable to occupation: chronic obstructive pulmonary disease (COPD); cancers of the bladder, nasal cavity, larynx, lung and pleura; leukaemia and lymphoma; accidental causes. Among the economic sectors with a significant excess mortality, the following are well documented in the literature: mortality due to COPD in the coal and peat-bog sectors; due to leukaemia among farmers; due to sino-nasal tumours in wood-working and furniture production; due to cancer of the larynx, lung, and pleura in occupations where there was probable exposure to asbestos (fishing and maritime transport, non-metal mining, building industry, and naval, train and aircraft construction); due to silicosis in industries with potential exposure to crystalline silica; due to accidental causes in the building industry and farming. Other mortality excesses and deficits, especially those due to bladder and lympho-haemopoietic cancers, appear to be only partly consistent with those described by other authors.

DISCUSSION

The feasibility of developing a surveillance system of occupational mortality based on the INPS source was found to be good, and, at least among males, for 75% of the deceased subjects historical information existed concerning the economic sectors registered in the INPS records. The results obtained would appear to indicate that the system is capable of highlighting risk excesses due to widespread exposure in the industries examined, regarding diseases for which there is a strong association with exposure. On the other hand, due to the inherent limits of the study's design (lack of a complete work history and of precise information on the jobs held) its use is not recommended in the surveillance of diseases with a low proportion attributable to a risk factor, or with wide exposure variability in a given sector among the various jobs.

The role of individual and contextual socioeconomic circumstances on mortality: analysis of time variations in a city of north west Italy

STUDY OBJECTIVE

To evaluate the independent and mutual effects of neighbourhood deprivation and of individual socioeconomic conditions on mortality and to assess the trends over the past 30 years and the residual neighbourhood heterogeneity.

DESIGN

General and cause specific mortality was analysed as a function of time period, highest educational level achieved, housing conditions, and neighbourhood deprivation, using multilevel Poisson models stratified by gender and age class.

SETTING

The study was conducted in Turin, a city in north west Italy with nearly one million inhabitants and consisting of 23 neighbourhoods.

PARTICIPANTS

The study population included three cohorts of persons aged 15 years or older, recorded in the censuses of 1971, 1981, and 1991 and followed up for 10 years after each census.

MAIN RESULTS

Individual and contextual socioeconomic conditions showed an independent and significant impact on mortality, both among men and women, with significantly higher risks for coronary heart and respiratory diseases among people, aged less than 65 years, residing in deprived neighbourhoods (9% and 15% excess for coronary heart diseases, 20% and 24% for respiratory diseases, respectively for men and women living in deprived neighbourhoods compared with rich). The decreasing time trend in general mortality was less pronounced among men with lower education and poorer housing conditions, compared with their more advantaged counterparts; the same was found in less educated women aged less than 65 years.

CONCLUSIONS

These results and further developments in the evaluation of impact and mechanisms of other contextual effects can provide information for both health and non-health oriented urban policies.