Trehalose promotes atherosclerosis regression in female mice

Introduction

Atherosclerosis is a chronic inflammatory disease caused by the deposition of lipids within the artery wall. During atherogenesis, efficient autophagy is needed to facilitate efferocytosis and cholesterol efflux, limit inflammation and lipid droplet buildup, and eliminate defective mitochondria and protein aggregates. Central to the regulation of autophagy is the transcription factor EB (TFEB), which coordinates the expression of lysosomal biogenesis and autophagy genes. In recent years, trehalose has been shown to promote TFEB activation and protect against atherogenesis. Here, we sought to investigate the role of autophagy activation during atherosclerosis regression.

Methods and results

Atherosclerosis was established in C57BL/6N mice by injecting AAV-PCSK9 and 16 weeks of Western diet feeding, followed by switching to a chow diet to induce atherosclerosis regression. During the regression period, mice were either injected with trehalose concomitant with trehalose supplementation in their drinking water or injected with saline for 6 weeks. Female mice receiving trehalose had reduced atherosclerosis burden, as evidenced by reduced plaque lipid content, macrophage numbers and IL-1β content in parallel with increased plaque collagen deposition, which was not observed in their male counterparts. In addition, trehalose-treated female mice had lower levels of circulating leukocytes, including inflammatory monocytes and CD4+ T cells. Lastly, we found that autophagy flux in male mice was basally higher than in female mice during atherosclerosis progression.

Conclusions

Our data demonstrate a sex-specific effect of trehalose in atherosclerosis regression, whereby trehalose reduced lipid content, inflammation, and increased collagen content in female mice but not in male mice. Furthermore, we discovered inherent differences in the autophagy flux capacities between the sexes: female mice exhibited lower plaque autophagy than males, which rendered the female mice more responsive to atherosclerosis regression. Our work highlights the importance of understanding sex differences in atherosclerosis to personalize the development of future therapies to treat cardiovascular diseases.

Plasminogen Activator Inhibitor-1–Positive Platelet-Derived Extracellular Vesicles Predicts MACE and the Proinflammatory SMC Phenotype

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This study shows the existence of PAI-1⁺ PEVs. Approximately 20% of plasma PAI-1 is composed of PAI-1⁺ PEVs.

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Elevated PAI-1⁺ PEV levels were predictive of 1-year major adverse cardiac events in both the discovery and the validation cohort, with larger effect sizes than other clinical biomarkers.

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High PAI-1⁺ PEV levels did not affect thrombogenicity.

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Increasing doses of PAI-1⁺ PEVs promoted the proinflammatory VSMC state by enhancing proliferation and migration. Inhibition of the PAI-1:low-density lipoprotein–related receptor-1 pathway dampened the proinflammatory VSMC changes.

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PAI-1⁺ PEV is a promising biomarker for major adverse cardiac events, and targeting the PAI-1⁺ PEV–VSMC interaction may offer a novel target to modulate cardiac events in patients with coronary artery disease.

Patients with established coronary artery disease remain at elevated risk of major adverse cardiac events. The goal of this study was to evaluate the utility of plasminogen activator inhibitor-1–positive platelet-derived extracellular vesicles as a biomarker for major adverse cardiac events and to explore potential underlying mechanisms. Our study suggests these extracellular vesicles as a potential biomarker to identify and a therapeutic target to ameliorate neointimal formation of high-risk patients.

miR-223 Exerts Translational Control of Proatherogenic Genes in Macrophages

A significant burden of atherosclerotic disease is driven by inflammation. Recently, microRNAs (miRNAs) have emerged as important factors driving and protecting from atherosclerosis. miR-223 regulates cholesterol metabolism and inflammation via targeting both cholesterol biosynthesis pathway and NF_kB signaling pathways; however, its role in atherosclerosis has not been investigated. We hypothesize that miR-223 globally regulates core inflammatory pathways in macrophages in response to inflammatory and atherogenic stimuli thus limiting the progression of atherosclerosis.

Abstract 383: MLKL (Mixed Lineage Kinase Domain-like Protein) In The Splenic Microenvironment Restrains Hematopoietic Contributions To The Atherosclerotic Plaque

The mixed lineage kinase domain-like protein (MLKL) was first discovered in 2012 as the executioner of necroptosis. In line with this, we showed that MLKL knockdown ( Mlkl KD) by administration of antisense oligonucleotides to atherosclerotic-prone Apoe -knockout ( Apoe -/-) mice did indeed decrease necroptosis and necrotic core in the atherosclerotic plaque. However, there were no changes in overall plaque area, suggesting additional roles of MLKL during atherosclerosis. During atherogenesis, the spleen allows for the expansion of hematopoietic stem and progenitor cells (HSPCs) and mature myeloid cells that drive atherogenesis. Accordingly, we observed splenomegaly with an expansion of splenic HSPCs and mature myeloid cells upon Mlkl KD. However, bone marrow transplantation studies revealed that MLKL did not impact hematopoiesis through its expression in hematopoietic cells. Within hematopoietic reservoirs such as the spleen, HSPCs are regulated by their interaction with microenvironmental cell types, including endothelial cells. We thus hypothesized that MLKL preserves the microenvironment to repress hematopoiesis in the spleen during atherosclerosis. Flow cytometry and immunofluorescence staining during a time course of atherosclerosis revealed a progressive decrease of splenic endothelial cells that was correlated with a reduction of MLKL endogenously or by Mlkl KD, suggesting that splenic MLKL modulates the endothelial cells known to regulate hematopoiesis. RNA sequencing of these splenic endothelial cells revealed two major pathways that were perturbed upon Mlkl KD, including cell cycle and factors related to leukocyte differentiation. Adoptive transfer of CD45.1 HSPCs to CD45.2 Apoe -/- mice during Mlkl KD revealed an expansion of mature immune cells in the spleen as compared to control, together demonstrating the influence of MLKL on the splenic microenvironment and subsequently hematopoiesis. In conclusion, we here demonstrate a novel role for MLKL in regulating the balance of hematopoiesis, specifically through preservation of splenic endothelial cells that promote HSPC quiescence, and more generally highlight the contributions of the spleen and its impact on inflammatory pathways that potentiate atherogenesis.

Abstract 102: Autophagy Is Differentially Regulated In Leukocyte And Nonleukocyte Foam Cells During Atherosclerosis

Atherosclerosis is characterized by a build-up of foam cells in the arterial wall, resulting from excess cholesterol uptake and accumulation of cytosolic lipid droplets (LDs). Autophagy has been shown to be atheroprotective in part by promoting the catabolism of LDs which liberates free cholesterol for efflux out of foam cells to cholesterol acceptors (ApoA-I or HDL) for removal from the body. Apart from macrophages (MΦ), vascular smooth muscle cells (VSMCs) comprise 50-70% of foam cells in the plaques. Unlike MΦ, the capacity of VSMC foam cells to metabolize cholesterol via autophagy is unknown. Here, w e performed a comparative analysis of the autophagic capacity and cholesterol efflux of arterial foam cell subtypes of the atherosclerotic plaque .

Atherosclerosis was induced in hypercholesterolemic autophagy reporter mice (GFP-LC3 mice receiving PCSK9-AAV and fed a Western diet). Autophagic flux in aortic digests was assessed by quantifying GFP-LC3 fluorescence after ex vivo treatment with the autophagy inhibitor Bafilomycin A1 or vehicle. MΦ foam cells displayed functional autophagy as shown by an accumulation of GFP-LC3 upon autophagy inhibition. In contrast, VSMC foam cells did not similarly accumulate GFP-LC3 upon bafilomycin treatment, suggesting dysfunction autophagy in these cells. Additionally, immunostaining of late-stage aortic roots showed MΦ, but not VSMC, foam cells induction of the active autophagy marker pATG16L1. Cell culture studies of lipid loaded MΦ and VSMC corroborated this inability for VSMCs to initiate autophagy in vivo .

In vitro , MΦ foam cells effluxed cholesterol to ApoA-I (14%) and HDL (50%), whereas VSMC foam cells minimally effluxed cholesterol to HDL (7%) but not apoA-I. However, unlike MΦ foam cells, VSMC efflux was pharmacologically induced by treatment with metformin.

Our data therefore demonstrates a lack of functional autophagy in VSMC, as compared to MΦ foam cells, which impairs their ability to perform cholesterol efflux. This autophagy defect in VSMC foam cells can be increased by autophagy activation using metformin, highlighting both the importance of understanding cholesterol metabolism in all foam cell populations and a new avenue to treat atherosclerosis.

Abstract 207: Autophagy Is Differentially Regulated In Leukocyte And Nonleukocyte Foam Cells During Atherosclerosis

Atherosclerosis is characterized by a build-up of foam cells in the arterial wall, resulting from excess cholesterol uptake and accumulation of cytosolic lipid droplets (LDs). Autophagy has been shown to be atheroprotective in part by promoting the catabolism of LDs which liberates free cholesterol for efflux out of foam cells to cholesterol acceptors (ApoA-I or HDL) for removal from the body. Apart from macrophages (MΦ), vascular smooth muscle cells (VSMCs) comprise 50-70% of foam cells in the plaques. Unlike MΦ, the capacity of VSMC foam cells to metabolize cholesterol via autophagy is unknown. Here, we performed a comparative analysis of the autophagic capacity and cholesterol efflux of arterial foam cell subtypes of the atherosclerotic plaque.

Atherosclerosis was induced in hypercholesterolemic autophagy reporter mice (GFP-LC3 mice receiving PCSK9-AAV and fed a Western diet). Autophagic flux in aortic digests was assessed by quantifying GFP-LC3 fluorescence after ex vivo treatment with the autophagy inhibitor Bafilomycin A1 or vehicle. MΦ foam cells displayed functional autophagy as shown by an accumulation of GFP-LC3 upon autophagy inhibition. In contrast, VSMC foam cells did not similarly accumulate GFP-LC3 upon bafilomycin treatment, suggesting dysfunction autophagy in these cells. Additionally, immunostaining of late-stage aortic roots showed MΦ, but not VSMC, foam cells induction of the active autophagy marker pATG16L1. Cell culture studies of lipid loaded MΦ and VSMC corroborated this inability for VSMCs to initiate autophagy in vivo .

In vitro , MΦ foam cells effluxed cholesterol to ApoA-I (14%) and HDL (50%), whereas VSMC foam cells minimally effluxed cholesterol to HDL (7%) but not apoA-I. However, unlike MΦ foam cells, VSMC efflux was pharmacologically induced by treatment with metformin.

Our data therefore demonstrates a lack of functional autophagy in VSMC, as compared to MΦ foam cells, which impairs their ability to perform cholesterol efflux. This autophagy defect in VSMC foam cells can be increased by autophagy activation using metformin, highlighting both the importance of understanding cholesterol metabolism in all foam cell populations and a new avenue to treat atherosclerosis.

Intercepting IRE1 kinase-FMRP signaling prevents atherosclerosis progression

Fragile X Mental Retardation protein (FMRP), widely known for its role in hereditary intellectual disability, is an RNA‐binding protein (RBP) that controls translation of select mRNAs. We discovered that endoplasmic reticulum (ER) stress induces phosphorylation of FMRP on a site that is known to enhance translation inhibition of FMRP‐bound mRNAs. We show ER stress‐induced activation of Inositol requiring enzyme‐1 (IRE1), an ER‐resident stress‐sensing kinase/endoribonuclease, leads to FMRP phosphorylation and to suppression of macrophage cholesterol efflux and apoptotic cell clearance (efferocytosis). Conversely, FMRP deficiency and pharmacological inhibition of IRE1 kinase activity enhances cholesterol efflux and efferocytosis, reducing atherosclerosis in mice. Our results provide mechanistic insights into how ER stress‐induced IRE1 kinase activity contributes to macrophage cholesterol homeostasis and suggests IRE1 inhibition as a promising new way to counteract atherosclerosis.

Autophagy Is Differentially Regulated in Leukocyte and Nonleukocyte Foam Cells During Atherosclerosis

RATIONALE

Atherosclerosis is characterized by an accumulation of foam cells within the arterial wall, resulting from excess cholesterol uptake and buildup of cytosolic lipid droplets (LDs). Autophagy promotes LD clearance by freeing stored cholesterol for efflux, a process that has been shown to be atheroprotective. While the role of autophagy in LD catabolism has been studied in macrophage-derived foam cells, this has remained unexplored in vascular smooth muscle cell (VSMC)-derived foam cells that constitute a large fraction of foam cells within atherosclerotic lesions.

OBJECTIVE

We performed a comparative analysis of autophagy flux in lipid-rich aortic intimal populations to determine whether VSMC-derived foam cells metabolize LDs similarly to their macrophage counterparts.

METHODS AND RESULTS

Atherosclerosis was induced in GFP-LC3 transgenic mice by PCSK9 (proprotein convertase subtilisin/kexin type 9)-adeno-associated viral injection and Western diet feeding. Using flow cytometry of aortic digests, we observed a significant increase in dysfunctional autophagy of VSMC-derived foam cells during atherogenesis relative to macrophage-derived foam cells. Using cell culture models of lipid-loaded VSMC and macrophage, we show that autophagy-mediated cholesterol efflux from VSMC foam cells was poor relative to macrophage foam cells, and largely occurs when HDL (high-density lipoprotein) is used as a cholesterol acceptor, as opposed to apoA-1 (apolipoproteinA-1). This was associated with the predominant expression of ABCG1 in VSMC foam cells. Using metformin, an autophagy activator, cholesterol efflux to HDL was significantly increased in VSMC, but not in macrophage, foam cells.

CONCLUSIONS

These data demonstrate that VSMC and macrophage foam cells perform cholesterol efflux by distinct mechanisms, and that autophagy flux is highly impaired in VSMC foam cells, but can be induced by pharmacological means. Further investigation is warranted into targeting autophagy specifically in VSMC foam cells, the predominant foam cell subtype of advanced atherosclerotic plaques, to promote reverse cholesterol transport and resolution of the atherosclerotic plaque.

Abstract MP09: MLKL (Mixed Lineage Kinase Domain-like Protein) Is A Novel Regulator Of The Splenic Microenvironment That Restricts Hematopoiesis During Atherosclerosis

During atherosclerosis, macrophages within the aorta undergo necroptosis, a mode of pro-inflammatory cell death that is triggered by the phosphorylation of RIPK1 & RIPK3 and leads to the activation of the mixed lineage kinase domain-like protein (MLKL) and cell lysis. Our previous work demonstrated that while inhibition of MLKL decreased necroptosis and necrotic core in the plaque, unlike RIPK1 & RIPK3 this inhibition did not lead to overall decrease in plaque area, suggesting that MLKL may in fact participate in other processes that drive atherosclerotic plaque development. Because circulating leukocytes are recruited and contribute to the growing atheroma, and these leukocytes are derived from hematopoietic stem and progenitor cells (HSPCs) found in both the bone marrow (BM) and the spleen, we investigated whether these hematopoietic reservoirs became dysregulated upon loss of MLKL during atherogenesis. To induce atherogenesis, Apoe -knockout mice ( Apoe -/-) were fed a high fat-high cholesterol diet for 16 weeks while receiving weekly subcutaneous administration of antisense oligonucleotides (ASOs) to knockdown MLKL expression. In the Apoe -/- mice receiving MLKL ASO we observed a 3.1-fold increase in splenomegaly compared to the control ASO, specifically with an expansion of the splenic red pulp, the area of splenic hematopoiesis. Furthermore, flow cytometry revealed a significant increase in myeloid HSPCs and mature myeloid populations in the spleen, but not the BM, after MLKL knockdown. However, no changes were observed in these hematopoietic measures after transplantation of Ldlr -knockout mice with MLKL-knockout BM, indicating that MLKL restricts hematopoiesis through its regulation of non-hematopoietic cells of the splenic niche. Indeed, upon MLKL knockdown in the Apoe -/- mice we observed a >50% reduction in splenic endothelial cells, which are required to promote HSPC quiescence and repress hematopoiesis. These data therefore demonstrate a novel role for MLKL on preserving splenic endothelial cells to limit immune cell development during atherosclerosis, and more generally, highlight the importance of the dysregulation of the splenic microenvironment to contributing to the inflammatory processes that drive atherosclerosis.

Identification of novel lipid droplet factors that regulate lipophagy and cholesterol efflux in macrophage foam cells

Macrophage autophagy is a highly anti-atherogenic process that promotes the catabolism of cytosolic lipid droplets (LDs) to maintain cellular lipid homeostasis. Selective autophagy relies on tags such as ubiquitin and a set of selectivity factors including selective autophagy receptors (SARs) to label specific cargo for degradation. Originally described in yeast cells, "lipophagy" refers to the degradation of LDs by autophagy. Yet, how LDs are targeted for autophagy is poorly defined. Here, we employed mass spectrometry to identify lipophagy factors within the macrophage foam cell LD proteome. In addition to structural proteins (e.g., PLIN2), metabolic enzymes (e.g., ACSL) and neutral lipases (e.g., PNPLA2), we found the association of proteins related to the ubiquitination machinery (e.g., AUP1) and autophagy (e.g., HMGB, YWHA/14-3-3 proteins). The functional role of candidate lipophagy factors (a total of 91) was tested using a custom siRNA array combined with high-content cholesterol efflux assays. We observed that knocking down several of these genes, including Hmgb1, Hmgb2, Hspa5, and Scarb2, significantly reduced cholesterol efflux, and SARs SQSTM1/p62, NBR1 and OPTN localized to LDs, suggesting a role for these in lipophagy. Using yeast lipophagy assays, we established a genetic requirement for several candidate lipophagy factors in lipophagy, including HSPA5, UBE2G2 and AUP1. Our study is the first to systematically identify several LD-associated proteins of the lipophagy machinery, a finding with important biological and therapeutic implications. Targeting these to selectively enhance lipophagy to promote cholesterol efflux in foam cells may represent a novel strategy to treat atherosclerosis.Abbreviations:ADGRL3: adhesion G protein-coupled receptor L3; agLDL: aggregated low density lipoprotein; AMPK: AMP-activated protein kinase; APOA1: apolipoprotein A1; ATG: autophagy related; AUP1: AUP1 lipid droplet regulating VLDL assembly factor; BMDM: bone-marrow derived macrophages; BNIP3L: BCL2/adenovirus E1B interacting protein 3-like; BSA: bovine serum albumin; CALCOCO2: calcium binding and coiled-coil domain 2; CIRBP: cold inducible RNA binding protein; COLGALT1: collagen beta(1-O)galactosyltransferase 1; CORO1A: coronin 1A; DMA: deletion mutant array; Faa4: long chain fatty acyl-CoA synthetase; FBS: fetal bovine serum; FUS: fused in sarcoma; HMGB1: high mobility group box 1; HMGB2: high mobility group box 2: HSP90AA1: heat shock protein 90: alpha (cytosolic): class A member 1; HSPA5: heat shock protein family A (Hsp70) member 5; HSPA8: heat shock protein 8; HSPB1: heat shock protein 1; HSPH1: heat shock 105kDa/110kDa protein 1; LDAH: lipid droplet associated hydrolase; LIPA: lysosomal acid lipase A; LIR: LC3-interacting region; MACROH2A1: macroH2A.1 histone; MAP1LC3: microtubule-associated protein 1 light chain 3; MCOLN1: mucolipin 1; NBR1: NBR1, autophagy cargo receptor; NPC2: NPC intracellular cholesterol transporter 2; OPTN: optineurin; P/S: penicillin-streptomycin; PLIN2: perilipin 2; PLIN3: perilipin 3; PNPLA2: patatin like phospholipase domain containing 2; RAB: RAB, member RAS oncogene family; RBBP7, retinoblastoma binding protein 7, chromatin remodeling factor; SAR: selective autophagy receptor; SCARB2: scavenger receptor class B, member 2; SGA: synthetic genetic array; SQSTM1: sequestosome 1; TAX1BP1: Tax1 (human T cell leukemia virus type I) binding protein 1; TFEB: transcription factor EB; TOLLIP: toll interacting protein; UBE2G2: ubiquitin conjugating enzyme E2 G2; UVRAG: UV radiation resistance associated gene; VDAC2: voltage dependent anion channel 2; VIM: vimentin.

Loss of MLKL (Mixed Lineage Kinase Domain-Like Protein) Decreases Necrotic Core but Increases Macrophage Lipid Accumulation in Atherosclerosis

OBJECTIVES

During the advancement of atherosclerosis, plaque cellularity is governed by the influx of monocyte-derived macrophages and their turnover via apoptotic and nonapoptotic forms of cell death. Previous reports have demonstrated that programmed necrosis, or necroptosis, of plaque macrophages contribute to necrotic core formation. Knockdown or inhibition of the necrosome components RIPK1 (receptor-interacting protein kinase 1) and RIPK3 (receptor-interacting protein kinase 3) slow atherogenesis, and activation of the terminal step of necroptosis, MLKL (mixed lineage kinase domain-like protein), has been demonstrated in advanced human atherosclerotic plaques. However, whether MLKL directly contributes to lesion development and necrotic core formation has not been investigated. Approaches and Results: MLKL expression was knocked down in atherogenic Apoe-knockout mice via the administration of antisense oligonucleotides. During atherogenesis, Mlkl knockdown decreased both programmed cell death and the necrotic core in the plaque. However, total lesion area remained unchanged. Furthermore, treatment with the MLKL antisense oligonucleotide unexpectedly reduced circulating cholesterol levels compared with control antisense oligonucleotide but increased the accumulation of lipids within the plaque and in vitro in macrophage foam cells. MLKL colocalized with the late endosome and multivesicular bodies in peritoneal macrophages incubated with atherogenic lipoproteins. Transfection with MLKL antisense oligonucleotide increased lipid localization with the multivesicular bodies, suggesting that upon Mlkl knockdown, lipid trafficking becomes defective leading to enhanced lipid accumulation in macrophages.

CONCLUSIONS

These studies confirm the requirement for MLKL as the executioner of necroptosis, and as such a significant contributor to the necrotic core during atherogenesis. We also identified a previously unknown role for MLKL in regulating endosomal trafficking to facilitate lipid handling in macrophages during atherogenesis.

Quantifying Cellular Cholesterol Efflux

Measuring cholesterol efflux involves the tracking of cholesterol movement out of cells. Cholesterol efflux is an essential mechanism to maintain cellular cholesterol homeostasis, and this process is largely regulated via the LXR transcription factors and their regulated genes, the ATP-binding cassette (ABC) cholesterol transporters ABCA1 and ABCG1. Typically, efflux assays are performed utilizing radiolabeled cholesterol tracers to label intracellular cholesterol pools, and these assays may be tailored to quantify the efflux of exogenously delivered cholesterol or alternatively the efflux of newly synthesized (endogenous) cholesterol, in different cell types (macrophages, hepatocytes). Cholesterol efflux may also be customized to quantify cholesterol flux out of the cell to various exogenous cholesterol acceptors, such as apolipoprotein A-I, high-density lipoprotein, or methyl-beta-cyclodextrin, depending on the purpose of the experiment. Here, we provide comprehensive protocols to quantify the net flux of cholesterol out of cells and recommendations on how this assay may be tailored as a function of the experimental question at hand.

[Disaster victims of the 1996 Saguenay floods: problems experienced and psychological consequences.]

The July 1996 Saguenay floods affected an important part of the region's population. Disasters of this nature subject victims to particularly difficult psycho-emotional experiences. From a qualitative study of the clinical analysis of 30 case history, this exploratory research describes the impact of this disaster on the lives of the victims and evaluates the consequences on their psychological health. Results indicate that this disaster has greatly disrupted the lives of victims entailing several problems as well as a deterioration of their mental health translating into serious psychological problems and disorders.

[Psychological and physical health of the July 1996 disaster victims: A comparative study between victims and non-victims.]

In July 1996, the Saguenay-Lac-St-Jean region suffered one of the greatest natural disasters in Québec's history. This article presents results of a study aiming at comparing, two years after the flood, the physical and psychological health condition of victims (n=177) to that of non-victims (n=168). The results indicate that victims, - regardless of their gender - present a psychological well-being as well as a post-disaster physical health that is different from non-victims. Disaster victims are much more numerous than non-victims in considering that their health is bad or average and in witnessing new health problems or the exacerbation of existing problems. Victims also present more manifestations of prosttraumatic stress and somatic complaints, have higher levels of depression, anxiety and social dysfunction than non-victims. However, no significant difference between subjects was revealed concerning severe depression. Results obtained corroborated that of other studies. After a natural or technological disaster involving important material damages to individual belongings, victims are more affected than non-victims concerning their psychological and physical health.

[Redefining habitat and mental health of flood victims.]

During the July 1996 floods in the Saguenay area, many families lost everything : house, land and personal belongings. This disturbing situation forced many victims to let go of their home. A review of the literature has allowed to conclude that individuals develop profound feelings towards their homes and that its destruction entails disorganization as well as negative thoughts threatening their psychological equilibrium. With the objective of identifying the consequences of this disaster on the concept of home and mental health of victims, an exploratory study was realized during winter 1998 with 69 subjects having lost all their belongings. The data collected confirmed what has been raised in the scientific literature : many individuals have been profoundly scarred by this disaster on both levels of concept of home and psychosocial health. Two years following the disaster, nostalgia and disappointment are still present for most individuals who have been unable to find a new environment where they truly feel at home.